i

FINAL REPORT SUBMISION OF PROJECT WITH TITLE

DESIGN AND DEVELOPMENT OF

SPEED CONTROLLED FIVE PHASE INDUCTION MOTOR WITH

TEMPERATURE ANALYSIS AT VARIOUS PARTS OF THE

INDUCTION MOTOR WITH HARMONIC EFFECTS

Submitted to

UGC NEW DELHI

Principal Investigator:

Dr. MANJESH M Sc. Ph.D Associate Professor

DEPARTMENT OF ELECTRONICS SCIENCE

BANGALORE UNIVERSITY

JNANABHARATHI,

BANGALORE – 560056

2015-18

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F O R E W O R D

The design and development of multi/poly phase drives in induction motor is a trending

concept for the present technology needs. The interest on Multi/poly phase drives is limited

because of the unavailability of power supply. The Multi/poly phase power system design leads

to the interest of Polyphone motor loads. The research work published about five phase

inverter/motor drives are few in the literature survey. Out of these available few literature survey

Multi/poly phase offers major advantages over three phase drives. Realizing these advantages,

simulation and experimental analysis of five phase inverter/motor drive is studied. Harmonics

generation and its effects on induction motor are discussed thoroughly and also reduction of

these harmonics are presented in five phase inverter/motor drive using filters.

The most popular speed and torque control technique is by variable/frequency method.

The V/F control technique is used to vary the speed of five phase induction motor. The major

factor affecting the induction motor is the overheating issues. The stator winding is predominant

because of the copper more lose, the lifetime of the insulation of stator winding depends on the

Class of induction motor. This problem is studied and in order to limit overheating, certain

measures are discussed. Thermal model of the five phase induction motor are designed and used

to predict the temperature at various parts of the five phase induction motor drives. By

developing a thermal model it allows rapid and accurate estimation of the temperature

distribution in an induction machine. Harmonic and THD comparison between the five phase

inverter/motor drives is analyzed. The reduction of harmonics and THD, temperature response of

the stator windings is studied and presented in the thesis.

Prof. Thimmegowda

Vice Chancellor of Banglore Univrsity

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AKNOWLEDGEMENT

The investigator is highly grateful to Prof. Thimmegowda, Hon’ble Vice-

Chancellor, Bangalore University and Prof. Seethamma, Registrar, Bangalore

University for their support and encouragement in re-establishing the Power

Electronics research laboratory in the department of Electronic Science, Bangalore

University, Jnanabharathi, Bangalore.

The author express sincere gratitude to the Chairman Prof. Mahesh for his

help and advice to the project. Also I extend my sincere thanks to my Ph.D Guide

Dr.Jyothi Balakrishnan for their help and suggestions to carry out this project, also

I thank my wife and my mother who have bared my absence at home when I was

busy in the project work. The author is highly indebted to The officers of UGC

new delhi support in getting this project work. I also thank Dr.Gunasekaran,

Professor, CEDT. IISC for their guidance and literature work carried out in Indian

Institute of science, Bangalore. I express my thanks to A.S.Anand, for his excellent

work using this project, he received his Ph.d. with a Title “Design and

Development of Five Phase induction motor drive and study of its stator

winding temperature at low speed”. I also thank Dr.Rajesh, Ph.d scholor under

my guidance, he also involved in this work to obtain the experimental results.

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THEME OF THE PROJECT

The Project has been sanctioned from UGC for a period of 2015-2018 with a Title “ Design and

development of speed control of five phase induction motor with temperature analysis at

various parts of the induction motor with harmonic effects”. The project has been carried out

with various tasks.

Task 1 : Detailed literature survey & study of functional theory

Task 2 : Design of speed control of Five phase induction motor

The overall architectural design and techniques are studied. This task is achieved in two stages.

a). Generation of Five phase PWM signals generated from Microcontroller to drive Five

phase induction motor.

b). Speed control of Five phase induction motor using Microcontroller, operated at very

low speed.

Task 3. Performance evaluation of the Five-phase induction motor: Operation of poly-phase

induction motor with high torque loads and study of harmonics with and without filter.

Task 4. Temperature characterization in the stator windings of the Five phase induction

motor:This task involves the temperature measurement in the stator windings of the poly phase

and three phase induction motor. This task involves minimization of stator windings of Five-

phase induction motor using the following technique

1.Filters is used to minimize the heat

Task 5: Preparation of the Final Technical Report (FTR)

ACHIEVEMENTS AS MENTIONED IN THE OBJECTIVES OF THE PROPOSED

PROJECT WORK:

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The main objectives of the proposed project work have been carried out as follows

1. The design and develop the speed controlled Five Phase induction motor using

microcontroller has been done.

2. The study the temperature at various parts of the Five Phase induction motor below

room temperature and above room temperature has been studied and obtained the

results, the results have been compared with and without filter.

3. The experimental study of Total Harmonic Distortion and Harmonics at the output of

the three phase induction motor using Power Analyzer is done and compared with and

without filter is presented in this report.

The work has been carried out in the department of electronic science Bangalore

University Bangalore. The reports describes the overall theme of the project work in

four chapters.

Chapter1: Describes the introduction and overall instruments purchased and used in

the project work.

Chapter2: Describes the design and construction of five phase inverter drive for motor

load using simulink matlab ( simulation work), and design and development of speed

control five phase induction motor drive with torque load.

Chapter3: Describes the Harmonic analysis with high torque load has been studied the

results have been compared with the simulation results.

Chapter4: Depicts the harmonic effects and Temperature analysis of five phase

induction motor with different torque loads.

Chapter5: Describes the overall conclusion of the project work carried out successfully.

vi

List of Publications

Journals with Impact Factor:

1. Harmonic analysis of single phase boost inverter using simulink Matlab, Mr. Chalvappa,

Mr. Ananda A S and Dr. Manjesh, International Journal of Innovative Science,

Engineering & Technology(IJISET), ISSN-2348-7968, Vol 2 Issue 5,Pg 491-493,May

2015. (IF=5.07)

2. Study of THD in Five Phase PWM Inverter Drive using Dual stage Common mode Filter

using Simulation, Ananda A S and Dr. Manjesh, International Journal of Electrical,

Electronics and Computer Systems (IJEECS), ISSN (Online): 2347-2820, Volume -3,

Issue-2, Pg 1-4, 2015 (IF=1.8)

3. Analysis of Harmonics in Five Phase Inverter Drive with Double tuned Filter using

Simulink/MATLAB, Ananda A S, Dr. Manjesh, International Journal of Advance

Electrical and Electronics Engineering (IJAEEE) ISSN (Print): 2278-8948, Volume-4

Issue-2, Pg 1-4, 2015 (IF=1.8)

UGC Listed Journals

1. Analysis of Comparative study of heat at various parts of the Three phase Induction

motor with Tuned filter using FPGA, Dr. Manjesh, Rajesh B and Ananda A S, Journal of

the Instrument society of India vol.47 No.2, Pg No. 38-39 June 2017

2. Speed control of a Five phase Induction Motor using FPGA by V/F method, Ananda A S

and Dr. Manjesh, Journal of the Instrument society of India vol.47 No.2, Pg No. 38-39

June 2017

3. Study of Stator winding Temperature in Five Phase Induction Motor Drive using LC

Filter at low frequency, Ananda A S and Dr. Manjesh, ITSI Transactions on Electrical

and Electronics Engineering (ITSI-TEEE) ISSN (PRINT) : 2320 – 8945, Volume -2,

Issue -4, Pg 39-41, 2014 (IF=2.04)

4. “Minimization of Harmonics, Total Harmonic Distortion and Thermal Analysis Of 5-

Phase Induction Motor Drive Using LC Filter With Delta Model Capacitor”, Dr. Manjesh

and Ananda A S. i-manager’s Journal on Electrical Engineering, vol-11, issue-3, Pg 1-8,

2018 (IF=2) DOI:10.26634/jee.11.3.14124

Book Chapter/Articles 1. Manjesh “Analysis of Ripple Voltage at the Output of Five-Phase Converter with Five-

Phase Inverter Drive for Renewable Energy Applications”. Advances in Smart Grid and

Renewable Energy. Lecture Notes in Electrical Engineering, vol 435. Springer,

Singapore, https://doi.org/10.1007/978-981-10-4286-7_25.

2. Ananda A.S., Manjesh “Performance Analysis of Series-Passive Filter in 5-Phase PWM

Inverter Drive and Harmonic Study Using Simulink/Matlab”. Advances in Power

Systems and Energy Management. Lecture Notes in Electrical Engineering, vol 436.

Springer, Singapore pg. 139-146 https://doi.org/10.1007/978-981-10-4394-9_14.

3. Manjesh, Dabhade N.S., Garg A., Bhoi A.K. “Reduction of THD in Nine-Phase

Induction Motor Drive with CLC Filter”. Advances in Power Systems and Energy

vii

Management. Lecture Notes in Electrical Engineering, vol. 436. Springer, Singapore, pg

23-31 https://doi.org/10.1007/978-981-10-4394-9_3.

4. Manjesh, Hasitha K., Bhoi A.K., Garg A. “Comparative Study of Harmonics and Total

Harmonic Distortion of Five-Phase Inverter Drive with Five-Phase Multilevel Inverter

Drive Using Simulink/MATLAB.” Advances in Power Systems and Energy

Management. Lecture Notes in Electrical Engineering, vol 436. Springer, Singapore, pg

33-38 https://doi.org/10.1007/978-981-10-4394-9_4.

5. “Design and Development of Buck-Boost Regulator for DC Motor Used in Electric

Vehicle for the Application of Renewable Energy”, Dr. Manjesh, K C Manjunath, Bhoi

A.K, Karma Sonam Sherpa, Advances in Smart Grid and Renewable Energy,. Lecture

notes in Electrical Engineering, vol-435. Springer, Singapore, pg 33-37,

https://doi.org/10.1007/978-981-10-4286-7_4.

6. Manjesh, Ananda A.S., Bhoi A.K., Sherpa K.S. “Evaluation of Harmonics and THD in

Five-Phase Inverter Constructed with High-Pass Filter by MATLAB Simulation”.

Advances in Systems, Control and Automation. Lecture Notes in Electrical Engineering,

vol 442 pg 1-7, Springer, Singapore, https://doi.org/10.1007/978-981-10-4762-6 1.

7. Manjesh, Rajesh B. “Suppression of Harmonics and THD Using Three-Level Inverter

with C-Type Filter at the Output of the Inverter Using Simulink/MATLAB”. Advances in

Systems, Control and Automation. Lecture Notes in Electrical Engineering, vol 442, pg

85-92, Springer, Singapore, https://doi.org/10.1007/978-981-10-4762-6_7.

8. Rajesh B., Manjesh “Three-Level Flying Capacitor Multilevel Inverter Is Used to

Suppress Harmonics at the Output of 3-Phase Inverter Drive and Study of Heat at

Various Parts of 3-Phase Induction Motor”. Advances in Systems, Control and

Automation. Lecture Notes in Electrical Engineering, vol 442, pg 213-223, Springer,

Singapore, https://doi.org/10.1007/978-981-10-4762-6_20.

International Conferences:

1. Study of THD in Five Phase PWM Inverter Drive using Dual stage Common mode Filter

using Simulation, Ananda A S and Dr. Manjesh, International Conference on Electrical,

Electronics, Computing and Communication Systems (EECCS'15) January 9th-10th 2015,

Pg No. 81-84

2. Study of Stator winding Temperature in Five Phase Induction Motor Drive using LC

Filter at low frequency, Ananda A S and Dr. Manjesh, International Conference on

Electrical, Electronics, Computing and Communication Systems (EECCS'15) January 9th-

10th 2015, Pg No. 85-87.

viii

3. Analysis of Harmonics in Five Phase Inverter Drive with Double tuned Filter using

Simulink/MATLAB, Ananda A S, Dr. Manjesh, International Conference on Electrical,

Electronics, Computing and Communication Systems (EECCS'15) 29th April, 2015, Pg

No. 78-82.

4. Analysis of Harmonics in a Five phase PWM Inverter with LR load and mitigation of

harmonics by π filter, Ananda A S and Dr. Manjesh, IEEE 2016 Biennial International

Conference on Power and Energy Systems: Towards Sustainable Energy (PESTSE). 21st

-23rd January 2016 DOI- 10.1109/PESTSE.2016.7516413.

5. Harmonics and THD analysis of Five phase Inverter Drive with Single Tuned Filter

using Simulink/MATLAB, Dr. Manjesh and Ananda A S, Third IEEE International

Conference on Emerging Technological Trends (ICETT-2016), 21st - 22nd October 2016,

Kollam, Kerala DOI- 10.1109/ICETT.2016.7873700

6. Performance analysis of Series-Passive filter in 5-phase PWM Inverter Drive and

Harmonic study using Simulink/Matlab, Ananda A S and Dr Manjesh, 1st Springer

International Conference on Emerging Trends and Advances in Electrical Engineering

and Renewable Energy (ETAEERE-2016), 17th-18th December, 2016 pg. no. 40.

7. Evaluation of harmonic and THD using LC filter for five phase induction motor drive at

low speed, Ananda A S and Dr Manjesh, International Conference on Circuit ,Power and

Computing Technologies (ICCPCT), 20th – 21st April 2017, Kollam, Kerala DOI-

10.1109/ICCPCT.2017.8074250

Ph.D Award:

One Ph.d has been awarded to Dr. Anand A.S under my guidance from Department of

Electronic Science, Bangalore University with a title ““Design and Development of

Five Phase induction motor drive and study of its stator winding

temperature at low speed”.

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Contents CHAPTER I: Introduction 1

1.1.1 Introduction 1

1.1.2 History of Induction Motor 2

1.1.3 Induction Motor 2

1.1.4 Variable Speed Drives 4

1.1.5 Inverter 7

1.1.6 Five Phase Voltage Source Inverter 11

1.1.7 Harmonics 14

1.1.8 Effects of Harmonics 17

1.1.9 Thermal issues in induction motors due to harmonics 18

1.2.0 Minimization of Harmonics 19

1.2.1 Thermal Model, Design of Induction Motor 28

CHAPTER II: Five Phase Inverter 2.1. Circuit diagram and Working 27

2.2 Simulation Results 30

2.3 Experimental Results 31

2.4 Comparison 33

2.5 Conclusion 34

CHAPTER III: Harmonic Analysis of Five phase Inverter 3.1. Harmonic Analysis 35

3.2. Conclusion 37

CHAPTER IV: Harmonic effects and Temperature analysis of five phase induction motor

with various filters 4.1.1 LC filter 38

4.2.1 LCL filter 46

4.3.1 π filter 53

4.4.1 Series-passive Filter 61

4.5.1 Common mode Filter 69

4.6.1 Single Tuned Filter 77

4.7.1 Double Tuned Filter 86

CHAPTER V: CONCLUSION

References 97

1

CHAPTER I

INTRODUCTION

1.1.1 Introduction

Global power consumption in total, industries use 29%, transportation use 33%, residential

sector use 29%, commercial sector use 8% and others use 3% of the total power generated from

the utility grid approximately the statistics obtained in the year 2015 [1]. In industries, the major

power consumer is induction motor, for example, power consumptions of all electrical

components in distillation, bottling company and food industry are as shown in Figure 1.1.1 (a)

and (b) respectively.

Figure 1.1.1 Power Consumption by the electrical component in (a) Distillation and Bottling Company (b) Food Industry

Out of total power, 47% power is utilized by the induction motor in distillation and bottling

company and 40% power is utilized by induction motor in food industries. Induction motors are

very essential in the various industries sectors, generally, they use 2/3rd of the all the electricity

fed to the industry. Considering UK nation, half of the total electricity is used by the induction

motor, over a 10 Million electric motor are at work daily and 3000 motors sold each day [2].

Electrical motors are extensively used all over the world in the industries.

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1.1.2 History of Induction Motor

Induction motor works on the principle of Faraday’s law of electromagnetic induction

which was discovered in 1860. By this study two of them have designed their own induction

machine, Galileo Ferraris (1885) and Nicola Tesla (1886). Both induction machines were

powered by single phase supply and have ferromagnetic stator core, Ferrari’s rotor was made up

of a copper cylinder and Tesla’s rotor is made up of a ferromagnetic cylinder, the working is

remained essentially the same.

Dolvio - Dobrovolsky has invented the induction motor with wound rotor in 1890. In

1900 induction motor used in industries, before 1910 first ever use of induction motor in

locomotives propulsion is successfully implemented in Europe and trial run reached a maximum

speed of 200 Km/h [3]. DC motors have been trending up to 1985, after the discovery of

Insulated Gate Bipolar Transistor, the complexity of drive circuit has been reduced, for the

construction of Pulse Width Modulation (PWM) Inverter, dc motors are replaced in the

industries by the induction motor with simple drive circuitry of induction motor. In the 21st

century there is no replacement found for induction motor compared to any other motor. These

days induction motor called “the racehorse of industry” replacing the earlier “the workhorse of

industry”.

1.1.3 Induction Motor

Generally AC machine are classified as follows.

Induction Machines

o Squirrel Cage Rotor

o Wound Rotor

Synchronous Machines

The induction motor converts electrical energy into mechanical energy. Considering all

types of motors squirrel cage motors are widely used all over the industries, also in residential

sectors because of its essential advantages such as it is rugged and simple construction, less cost,

lightweight, requires very less maintenance, good power factor and efficiency and robust, they

can operate in any environmental condition. Induction motors are available in various ranges

3

from Fractional horsepower (HP) to Multi-megawatt. For low power requirements, fractional HP

motors are used. The cross-sectional view of an induction motor is as shown in Figure 1.1.2.

Figure 1.1.2 Cross-sectional view of Induction motor

For better efficiency and power, three-phase squirrel cage motors have been used in the

industries. The phase windings are either in STAR or DELTA connection usually used. The

motor has 2 important parts i. e, a stationary stator and a revolving rotor, and a core made up of

laminated ferromagnetic steel sheets. In a wound rotor windings of the rotor is same as stator,

whereas in squirrel cage the rotor has to be squirrel cage-like structure with shorted end rings.

Stator windings directly fed to AC source, it creates a rotating magnetic field and it travels

through the air gap between the stator and rotor. This induces voltage and produces currents in

rotor windings. This produces rotational force in the motor to rotate, this rotational force is called

as torque. The speed of the rotating magnetic field is called as synchronous speed (NS)

Synchronous speed, NS = 120* f

p (1)

Where f = frequency applied, p = number of poles of motor

If the rotor and rotating magnetic field are rotating at the same speed or at synchronous

speed then no relative motion would exist between the rotor and rotating magnetic field,

therefore no voltage is induced into the rotor, no torque is developed. At any other speed (NR), it

induces rotor current and torque is developed. The difference between the synchronous speed

and actual rotor speed is called as Slip (S). Slip is necessary to produce torque, and it depends on

the motor load. An increase in the load of the motor will cause the rotor to slow down or increase

the slip, a decrease in load will cause the rotor to rotate fast or decrease slip. Slip is expressed in

percentage and calculated as follows.

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Slip, S = NS − NR

NS * 100 (2)

Where NR = actual rotor speed

Single phase and three phase AC source has dominant in the industries so far, because

AC source is easily available from a power grid and directly fed to the induction motor. Single

phase supply induction machines are abundantly used in home appliances such as fans, washing

machines, and Mixers grinders etc. Induction machines are used increasingly in wind turbines,

blowers, grinders, chippers, conveyors, shredders, crushers, mixers, cranes, extruders, refiners,

chillers and marine environment applications such as pumps, and compressors etc. The present

technology towards the motor drive system has drastically improved by the switching elements

like IGBT PWM inverter and smart power devices provides better efficiency, and this promotes

the researchers to design the Variable Speed Drives (VSD), as per the user requirement, the

VSD’s are designed for all applications in industries.

1.1.4 Variable Speed Drives

VSD’s are the most efficient (98% at full load) type of drives available around the world.

Industries are converting induction motor drives(IMD) into VSD, because it produces better

efficiency only at low slips [4], close to the synchronous speed of the induction motor by 10%

of the motor speed [3]. In the last span of the annual growth, the production of VSD is 9% where

IMD is 4%. This shows the interest in VSD is increasing because of its vast applications such as

pumps, compressors, used in transportation, ventilators, machine tools, robotics, hybrid or

electric vehicles, washing machines, centrifugal pumps, centrifugal fans, chillers condensers,

make-up air units (MUA), exhaust fans, variable air volume systems (VAV) etc. [3] [5]. Electric

trains, tractions, trolley buses are powered by VSD.

In the applications like the induction motor-based centrifugal pump, a speed reduction of

20% results in an energy savings of approximately 50%. This means that the motor user can

replace an energy inefficient mechanical motor drive and control system with a variable speed

drive. The VFD (voltage/frequency drive) not only controls the motor speed but can improve the

motor’s dynamic and steady-state characteristics as well. In addition, the VFD can reduce the

system’s average energy consumption [6]–[8]. The developed torque is proportional to slip, if the

5

motor operates with less slip, this leads to generate low speed as torque decreases. Speed and

torque can be varied by the following control techniques.

a. Stator Voltage Control

b. Rotor Voltage Control

c. Frequency Control

d. Stator Voltage and Frequency Control

e. Stator Current Control

f. Voltage, Current and Frequency control

a. Stator Voltage Control:

The voltage applied directly to the IMD is proportional to the square of the stator voltage.

If the rated voltage is applied to the stator, the motor rotates at rated speed and if less voltage is

applied to the stator, the air gap flux and torque are reduced producing less speed. This type of

control used in low-slip motors, at a lower voltage the range of speed is very narrow and used in

applications where low starting torque is required. It’s not suitable for constant-torque load

applications, due to the high harmonic current produced in stator and power factor is low in

stator voltage control and applications are fans, blowers, pumps.

b. Rotor Voltage Control:

This control technique is used in a wound type induction motor, the developed torque is

varied by varying the rotor resistance. It increases the starting torque while limiting the starting

current. Efficiency is less, voltage and currents are unstable in this control method. Due to the

unstable voltage and current, the torque developed is also unstable.

c. Frequency Control:

Generally, an induction motor fed rated voltage and rated frequency to achieve a rated

speed of the motor. According to Eq. (1) base speed of the motor depends on input frequency

and the number of poles of the motor. Since the number of poles is fixed in particular motor, the

frequency is the only parameter to vary considering the all other motors. If the voltage is kept

constant and frequency is varied in this control method, this increases the magnetic flux in

windings of the motor to the saturation level. At variable low frequencies and at rated voltage,

6

produces less reactance and high current in the windings. This control method is not

recommended for variable speed drive applications.

d. Stator Voltage and Frequency control:

In this control method stator voltage and frequency is kept constant, so the flux is also

constant. The maximum torque developed by the induction motor is directly proportional to the

ratio of the applied voltage and the frequency of supply. The speed can be varied by varying both

the voltage and the frequency, but keeping their ratio constant, the torque developed can be kept

constant throughout the speed range and starting torque increases. This technique is popularly

known as V/F control. The control of both voltage and frequency by keeping V/F constant can be

done using PWM Inverter. The inverter converts DC to AC, this power system is used to control

the induction motor. V/F control technique can be achieved by Voltage Source Inverter (VSI).

The torque vs. speed characteristic curve is as shown in Figure 1.1.3. The ratio kept constant

under all conditions produces constant torque from starting very low speed up to rated speed as

shown in characteristics curve and below the rated voltage and rated frequency constant torque is

produced and above the rated frequency toque decreases.

Figure 1.1.3 V/F control method’s characteristics curve

e. Stator Current Control:

The speed of the IMD can be controlled by the stator current control same as stator

voltage control, the response of the motor is different from the stator current control to voltage

control. This type of control technique is used in Current Source Inverter (CSI). In this control

7

maximum torque depends on the square of the input current, and it is independent of the input

frequency. At maximum current, the torque is low, as the voltage raises torque increases.

f. Voltage, Current and frequency Control:

Varying voltage, current, and frequency speed can be controlled, torque generation will

be different in this control by considering voltage, current and frequency. According to the

torque and speed requirement, a voltage, current, and frequency are being varied. By varying the

voltage it produces a constant torque, by varying current, the slip is altered, speed is controlled

by varying the frequency in this control method.

Out of all above techniques of speed control of induction motor V/F control technique is

widely used by the industries, due to its more efficiency and simple construction of PWM

inverter by the use of smart power devices. Hence the implementation V/F control technique are

discussed in this thesis to control the speed of the induction motor.

1.1.5 Inverter

An inverter is circuit which converter DC power into AC power. The inverter output AC

voltage and frequency may be rated or variable depends on the type of applications. The output

voltage of ideal inverter should be sinusoidal, the waveforms obtained experimentally are non-

sinusoidal. The inverters are widely used in application such as AC motor drives, AC Un-

interruptible Power supplies (UPS), Induction Heating, Variable speed motor Drives, Static VAR

generator and compensator etc. The construction of inverters with switches, remains forward

biased condition due to DC supply, hence self-controlled forward devices which are non-linear

devices such as Gate Turn-Off Thyristors (GTO), Bipolar Junction Transistors (BJT), Insulated

Gate Bipolar Transistor (IGBT), power Metal Oxide Semiconductor Field Effect Transistors

(MOSFET), and Integrated Gate-Commutated Thyristors (IGCT) are suitable. Inverters are

commonly constructed with IGBT’s or MOSFET’s and Power modules, and smart power

devices. Variable frequency motor drives are used ranging from hundred watts to kilowatts,

standard 50 Hz is used to run at rated speed. VSD’s run the motors at low frequency range from

5- 10 Hz [4]. Aerospace applications commonly use operating frequency as 400 Hz [9] and

electric traction uses 25 Hz as operating frequency. The most used IMD is three-phase motor

8

drives in the industries due to its various advantages and available from 1 HP to 5000 HP, but

single phase motors are available up to 5kW. An inverter is mainly of two types, Voltage Source

Inverter and Current Source Inverter. The difference is that in VSI DC voltage remains constant,

but in case of CSI DC input current remains constant. Effective use of inverter starts with single

phase VSI in earlier, after the advancement in semiconductor the three phase inverter gained a lot

of interest among the industries to use it for high power applications.

The single phase VSI circuit diagram is as shown in Figure 1.1.4, it consists of four

switches and fed with DC input and connected to load. MOSFET’s are used as the switches,

MOSFET won’t turn ON unless gate voltage is provided. Hence gate voltage is applied in such a

manner that MOSFET 1 and 4 is turned ON and conducts for 180º to produce +VDC at the output,

simultaneously at the same time MOSFET 2 and 3 remain in OFF condition during first half

cycle. In next half cycle MOSFET 2 and 3 turned on and conducts for 180º to produce –VDC at

the output and MOSFET 1 and 4 remain in OFF condition. Considering the switches MOSFET 1

and MOSFET 2, together they called as individual leg and prior turning ON MOSFET 1 the

other MOSFET 2 must be in OFF condition otherwise both switches will conduct and DC input

supply gets shorted this is as shown in single phase inverter drive Figure 1.1.4.

Figure 1.1.4 Circuit diagram of Single phase VSI

The anti-parallel diodes in the MOSFETs act as feedback diodes which feedback the load

reactive power. The gate pulses generated from microcontroller or FPGA are as shown in Figure

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1.1.5 and inverter output voltage is as shown in Figure 1.1.6 for single phase inverter drive

system. The frequency of the gate-pulses provided decides the frequency of inverter output,

that’s how VSD’s vary the frequency with respect input voltage to control the speed of the

induction motor.

Figure 1.1.5 Gate-pulses P 1- P 4 applied to MOSFET 1- MOFET 4

Figure 1.1.6 Output voltage of single phase voltage source inverter

Using single phase topology, three phase VSI is also constructed using 6 switches and load can

be STAR or DELTA form. The circuit diagram of three phase inverter is as shown in Figure

1.1.7. Each phase is 120º out of phase with each other in three phase inverter. S1 to S6 are the

MOSFETs used to construct three phase inverter drive, the control signals P1 to P6 are gate

pulses generated by the micro controller for the switches. Switches S1, S2, S3 are called as upper

group switches and switches S4, S5, S6 are called as lower group switches.

0 90 180 270 360

P 1

P 2

P 3

P 4

10

Figure 1.1.7 Circuit Diagram of Three phase Voltage Source Inverter

The inverter output frequency depends on the gate-pulse frequency, according to the user

requirement it can be modified. The input voltage must be fixed according to the V/F profile and

then it is connected to the inverter to control the induction motor for variable speed. As in single

phase inverter any one of switch will conduct in one leg similarly in three phase also, three phase

VSI has 3 legs hence any one switches will conduct in all 3 legs. All switches S1 to S6 will

conduct 180º conduction modes. 120º conduction modes also can be implemented, but 180º

conduction mode is industrial standard conduction mode, therefore 180º conduction mode is

selected for the experimental work. Gate-pulses initialized as shown in Figure 1.1.8. Gate pulses

decide when to switch ON and OFF the MOSFETs S1 – S6, the pattern of the switching

sequence is that any 2 switches from the upper group and one from the lower group conducts and

vice versa to produce the three phase line voltages.

In three phase out of 360º, for every 60º there will be a change in the switching sequence.

Considering from the Figure 1.1.8, from 0º to 60º P1, P3, P5 switches are “ON” time pulses, so

switches S1, S3, S5 are in ON state and the remaining are at OFF state. The switching pattern

changes 6 times, hence it is also called as 6 step inverter and switching takes place from 0º to

360º continuously goes on to produce the three phase line voltages as shown in Figure 1.1.9.

These 3 line voltages are then connected to the motor drives to vary the speed of the induction

motor.

11

Figure 1.1.8 Gate-pulses P 1-P 6 applied to S1 - S6 respectively

Figure 1.1.9 PWM Output voltage of 3 phase VSI consisting of 3 phases

1.1.6 Five Phase Voltage Source Inverter

Three phase AC supply is readily available throughout the world, three phase is

generated, transmitted, and distributed in three phase system. It is directly fed to the three phase

induction motors to run the motor at rated speed and to run the motor at variable speed. Three

phase VSI is designed and it is abundantly used in the industries to vary the speed of the motor.

Power electronic converters do not have limitations on number of legs in an inverter, the number

of phases in an inverter is same as their respective number of legs. Hence adding an additional

12

leg to an inverter increases the number of output phases. This degree of freedom leads to interest

in developing VSD’s with more than three phases. The growth of high phase orders motor drives

in the 19th century were less, after the advancement in low cost and reliable power switching

device availability researchers are being attracted to design the Multi/poly phase drives [10]

[11]–[36].

Multi/poly phase drives offers some distinct advantages over three phase drives, the major

advantages are

Higher torque density

Reduced torque pulsations

Great fault tolerance

Reduction in the required ratings per inverter leg

Better noise characteristics

Smoother torque due to the simultaneous increase of the frequency of torque pulsations

and reductions in torque ripple magnitude.

Multi/poly phase drives are restricted to some applications because of its drawback that

multi/poly phase input is not readily available. By generating the multi/poly phase power

researchers implemented extended the work to some of the applications and they succeeded, got

better results compared to three phase drives. Applications are ship propulsion, electric aircraft,

hybrid electric vehicles and electric traction. In high power applications considering ship

propulsion, the use of multi/polyphase drives enables reduction of required power ratings per

inverter leg. Whereas in previous, series and/or parallel combination of power electronic

switches are used to reduce the power ratings per inverter leg and this gives rise to create static

and dynamic voltage problems. This problem is overcome by the use of Multi/poly phase.

Considering safety-critical applications such as electric aircraft, the use of multi/poly phase

enables great fault tolerance such that loss in single phase in power system has less impact on the

power system [10], [36]–[48]. In Multi/poly phase, five phase VSI is trending in power systems

and more researchers are attracted towards five phase drives in recent years. This work

highlights the construction and development of five phase motor drives. The circuit diagram of

five phase induction motor drive is as shown in Figure 1.2. Ten switches from S1 to S10

MOSFETs are used to produce the five phase line voltages and fed to the five phase induction

13

motor to drive. The Five Phase power with Phase difference of 72⁰ is generated as Phase-A,

Phase-B, Phase-C, Phase-D, Phase-E represents the five phase line voltages.

Figure 1.2 Circuit Diagram of Five phase Induction Motor Drive

In order to drive the five phase motor a drive circuitry is constructed with control signals

generated from microcontroller or FPGA kit. The gate-pulses of five phase VSI is as shown in

Figure 1.2.1. Each phase is 72º out of Phase with each other in Five Phase Inverter. All the

switches conduct for a period of 180º. Switches S1, S2, S3, S4, and S5 are considered as upper

group switches and switches S6, S7, S8, S9, and S10 are considered as lower group switches.

Switching pattern in five Phase VSI is that, any 3 switches from the upper group and any 2

switches from the lower group conduct and vice versa to produce five phase line voltages.

Figure 1.2.1. Gate-pulses for five phase VSI

14

The Five Phase line voltages are as shown in Figure 1.2.2. Five Phase VSI is a 10 step

inverter, for every 360 there is a change in switching pattern, considering one complete cycle

360º. There are 10 different group of switches will conduct. In the first step i. e. from 0º to 36º,

switches S1, S4, S5, S7 and S8 will conduct to produce five phase line voltages. The major

concern while using inverters is that it generates non-sinusoidal AC waveform instead of a pure

sine wave which is considered having pure and better power quality. As observed in Single

phase, three phase, five phase inverter output voltage waveforms, the pure sine wave generation

is practically impossible because of the use of nonlinear devices.

Figure 1.2.210 Output Voltage of Five Phase VSI

1.1.7 Harmonics

Nonlinear devices are generally used for the inverter drives, hence the current is not

proportional to the applied voltage this leads the generation of “harmonics” [49]. Nonlinear

devices in power system give rise to deviations in voltage and current waveforms resulting in

waveform distortion called harmonic distortion. The term harmonics was originated from the

field of acoustics, elaborated as a single distorted waveform having the frequency equal to an

integer multiple of the fundamental frequency. Mathematically nonlinear devices imply having

the condition of superposition, nonlinear loads drew currents that may be discontinuous or in

15

pulses form of the sinusoidal voltage. Harmonics are expressed mathematically with the help of

mathematician Jean Baptiste Fourier in earlier 1800s formulated that a periodic non-sinusoidal

function of the fundamental frequency expressed as the sum of a sinusoidal function of the

frequencies, which are multiples of the fundamental frequency. The integer multiple of the

fundamental frequency is superimposed on the fundamental frequency, thus distortion in the

power quality arises leading to create additional problems within the power systems and inject

back to input AC mains.

Increasing the use of nonlinear devices in industries observed in this past decade and

estimated that more than 60% of the growth of nonlinear devices used in the power electronic

system. The most used nonlinear device system is converters and inverters, power system where

voltage and frequency are varied to power the equipment in the industries are the dominant

sources of harmonics in distribution or utility grid system. Some examples of power systems

using nonlinear devices are given below and grouped into 3 categories.

Large power converters/ Inverters which are used in High Voltage Direct Current

(HVDC) Transmission systems, and High voltage Alternating current Transmission

(HVAC) used for more VSD type applications, Wind and Solar power generation,

Thyristor controlled reactors.

Medium-size power converter/ Inverters which are used in manufacturing industries, oil

industries for motor speed control, electric railroad applications and in railway systems,

ranged in Kilo Voltage systems. Silicon controlled rectifier heating, induction heating,

arc welding.

Small Power converter/ Inverters which are used in residential sectors such as TV,

personal computers, copy machines, battery chargers, UPS, welders, printers, pumps etc.

Distribution Static Compensators (DSTATCOM) is another example of VSI where power system

is connected in shunt to distribution or utility grid system, produces more harmonics within the

power system which are used in Flexible AC Transmission system (FACTS). Fluorescent lamps,

tubes are highly nonlinear in their property, generates harmonics in distribution network. Electric

furnaces in industries are known to produce harmonics, with all the above-mentioned power

system their power quality is compromised with non-sinusoidal output, indeed producing

harmonic distortion in the power system. VSDs are the largest consumer of nonlinear loads in the

16

industries. Single phase, three phase, and multi/polyphase power systems are dominant in the

generation of harmonics in the industries.

A sinusoidal voltage or current which is dependent on time t is represented by the following

expressions.

Voltage, v(t) = V sin (ωt) (3)

Where ω= 2πf is the angular velocity of the periodic waveform,

Considering generally for periodic non-sinusoidal waveform the simplified Fourier expression

states:

v(t) = V0 + V1 sin (ωt)+ V2 sin (2ωt)+ V3 sin (3ωt)+ V4 sin (4ωt)+ V5 sin (5ωt)+ V6 sin (6ωt)+

V7 sin (7ωt)……..+ Vn sin (nωt)+. . . . (4)

V0 represents constant or DC component of the waveform and V1, V2, V3, V4 …Vn represents the

peak voltages of the successive terms of the expressions called Harmonic orders. The majority of

nonlinear devices produce odd multiple harmonic of the fundamental frequency such as 1st, 3rd,

5th, 7th, 9th, 11th, 13th…… etc. The first harmonic order has the frequency f, the third harmonic

order has frequency of 3f, and nth harmonic order has a frequency of nf. If the fundamental

frequency (f) is 50 Hz then, third harmonic order frequency is 3*50=150 Hz. The fundamental

frequency along with integer multiple of the fundamental frequency is as shown in Figure 1.2.3.

Figure 1.2.311 Superimposed harmonic orders on the fundamental frequency

17

Considering three phase inverter 3rd and their multiples 6th, 9th, 15th…. order are absent, so the

present orders of harmonics in three phase inverter are 1st, 5th, 7th, 11th, 13th, 17th… etc. In five

phase inverter 5th and their multiples 10th, 15th, 25th … orders are absent, the present harmonics

are 1st, 3rd, 7th, 9th, 11th, 13th, 17th…. Etc. The dominant harmonic order in five phase inverter in

3rd which is of 1/33% of the fundamental order.

These harmonics distortion can be expressed in total harmonic distortion (THD), describes the

net deviation due to all the harmonics, and it is a measure of the effective value of the harmonic

content of the distorted waveform, it can be calculated using the following expression.

THD =

√∑ (Vh2)

∞

h>1

V1 x 100 % (5)

Where Vh is the root mean square (RMS) value of the harmonic component h = 1, 2, 3, 4, 5 ….∞,

V1 represents the RMS value of the fundamental component. THD is a very important index

widely used to describe power quality issues in transmission and distribution power systems.

From the end user point of view, power quality must be having pure sinusoidal voltage

waveform and Total harmonic distortion within the thresholds dictated by the industry standards.

Since these are two major regulations which need to be fulfilled by the transmission and

distribution power systems. By injecting the harmonics various issues are obtained within the

power systems and also it will harm other peripherals connected to that AC power line [9], [49]–

[54].

1.1.8 Effects of Harmonics

Effects of harmonics depend on the power system connected and various types of loads, such as

industrial, commercial and residential loads. Generally, effect of harmonics is as follows

Poor power quality in utility grid because of Capacitor bank, since reactive power

overloads and there will be excessive losses.

Synchronous generators weak response because of increase in negative current loading,

endangering the rotor circuit and windings

In transformers, generation of harmonic fluxes, and increase in flux density, eddy current

heating issues and consequent de-rating.

18

In cables, de-rating occurs causing additional eddy current heating issues and skin effect

losses.

In telecommunications, increase of inductive interference.

Noise and interference generation in solid-state and microprocessors controlled power

systems

Relay malfunction, inrush current in distribution systems.

Interference with ripple voltage control and power line carrier systems, causing unstable

remote switching, load control and metering.

Unstable response of firing circuits considering Zero-voltage crossover detection.

Flicker in transmission lines.

Most of the above mentioned effects lead to overheating problems within the power system. The

harmonic current adversely affects with a wide range of power systems, industries are widely

equipped with transformer and motors hence harmonics does major effect while using

transformers and motors [49] causing additional losses, overheating and overloading. [55]–[68]

1.1.9 Thermal issues in induction motors due to harmonics

The impact of odd harmonics to the induction motor translated to a harmonic flux, and do

not contribute significantly to motor torque, but rotates at a frequency different than the rotor

synchronous frequency, basically inducing high frequency currents in the rotor. It decreases

motor efficiency, more overheating with vibrations and high-pitched noises. The highest

harmonic heating observed in large deep bars or double cage motors. The lower order harmonics

which are below 25th harmonic order are mainly considered to be a major threat to the induction

motor, having larger magnitude and lowers the motor impedance[49]. Excessive heating in the

motor depends on the THD generated from the inverter. Harmonic distortion produces elastic

deformation such as shaft deflection, parasitic torques, vibration noise, additional heating, and

lower the efficiency of induction motors [69]. The rotation of harmonic fluxes in the stator is

with or against the fundamental frequency, directly effects on the induction motor with losses,

such as losses in windage and friction losses, stator copper loss, core loss, rotor copper loss and

stray loss in the core and conductors of the motor. The effective rotor and stator leakage

inductance decreases and the resistance increase with frequency. The stator copper loss increases

in proportion to the square of the total harmonic current/voltage with an additional increase due

19

to skin effect on resistance at higher frequencies. The harmonics contributes to magnetic

saturation, and the effect of distorted voltage on core losses. The major loss components

influenced by harmonics are stator and rotor copper losses and stray losses. A harmonic THD

factor of 11% gives approximately 25% de-rating of general-purpose motors [69]. The harmonic

fluxes create tooth saturation and zigzag leakage produces unbalanced magnetic pull, which

moves around the rotor. The harmonic currents/voltage flowing in the induction motor’s, causes

additional heating effects on stator windings, in the conductors, and iron parts in the motor [54].

The negative class harmonics creates additional losses by inducing higher frequency currents and

negative torques in machine rotors, hence torque pulsations are created. The adverse effects of

harmonics in induction motors includes overstressing and heating on the insulation, machine

vibration, malfunctioning of the power systems which harms the motor’s lifespan, hence THD

must be suppressed in order to reduce the overheating in the induction motor which results

improvement of life time of the motor.

1.2.0 Minimization of Harmonics

Harmonic currents/voltages are created by nonlinear devices which induced in power

systems and eventually flow back to the source. Many of researchers are studied these harmonics

in the past and doing research presently for better power quality with various techniques to

reduce the harmonics. The pure sinusoidal waveform is every researcher’s goal, there are few

methods to reduce the harmonics such as filter technique, multi-level inverter technique and

modulation techniques. In this work, filter technique are adopted to reduce the harmonics and

THD in Five phase inverter and motor drive. Harmonic filters are broadly classified into passive

and active filters. Passive filters, as the name implies, it is constructed with passive components

such as resistors, inductors, and capacitors. The price of passive filters is rather low, and their

reliability is high, because of the low price passive filters are currently more popular. In filters

technique there are many inductor and capacitor based designs are available to reduce the

harmonics such as LC, LCL, CLC(𝜋), series-passive, single tuned, double tuned and common-

mode filters are used to reduce the harmonics [58]–[68], [70]–[77] [55]–[57], [70], [78]–[107].

A. LC filter:

The filter consists of inductor and capacitor, which couples to the load from the inverter, the

filter is placed next to the source of harmonic generation, many researchers studied and designed

20

LC filter to reduce harmonic in the power systems at different resonant frequencies. LC filter

without the resistor is commonly used by the designers, because resistor dissipates power. The

circuit diagram of LC filter is as shown in Figure 1.2.4.

Figure 1.2.412 Circuit diagram of LC filter

LC filter will offer a near zero impedance channel for the tuned resonant frequency. While

designing the filters, it is mandatory to monitor maximum current ripple from the inverter due to

switching action. Inductance is depend on the inverter’s maximum current ripple and capacitance

value is depend on the inverter’s voltage ripple from the switching action of the switches used in

the PWM inverter [108]–[118]. The resonant frequency f0 is calculated using the following

expression.

f0 = 1

2π√LC (6)

B. LCL filter

The LCL filter used to achieve a higher attenuation along with cost savings, also it is the one of

the advantage of overall weight and size reduction of the components. The circuit diagram of

LCL filter is as shown in Figure 1.2.5, consisting of L1 inductor with the inverter- side inductor,

L2 is the grid/load/induction motor side inductor and C1 is a capacitor. LCL filters have been

used in grid-connected inverters and pulse-width modulated active rectifiers, because they

minimize the amount of current distortion injected into the utility grid. The excellent

performance can be obtained in the range of power levels up to hundreds of kW, with the use of

small values of inductors and capacitors.

21

Figure 1.2.5 Circuit diagram of LCL filter

The higher harmonic attenuation of the LCL filter allows the use of lower switching frequencies

to meet harmonics constraints, as defined by harmonic standards [109], [112]–[114], [116]. The

resonant frequency f0 of the LCL-filter is given by:

f0 = 1

2π√

L1+L2

L1L2C (7)

C. π filter:

The name π – Filter implies to the resemblance of the circuit to a π shape with two shunt

capacitances (C1 and C2) and an inductor L1 as shown in Figure 1.2.6, compared to the other

type of filter, the π Filter has some advantages like higher dc voltage and smaller ripple factor.

But it also has some disadvantages like poor voltage regulation, high peak diode current, and it

has high peak inverse voltage. This filter is divided into two – a capacitor filter and a L-section

filter. The capacitor C1 does most of the filtering in the circuit and the remaining ripple is

removed by the L-section filter (L1-C2). C1 is selected to provide very low reactance to the

ripple frequency. The voltage regulation is poor for this circuit as the output voltage falls off

rapidly with increase in load current.

Figure 1.2.6 Circuit Diagram of π filter

22

The resonant frequency f0 is calculated using the following expression and considering C1= C2 =

C.

f0 = 1

2π√LC (8)

D. Series-passive Filter

A series-passive filter is designed to suppress the harmonics and placed between the load and

inverter. Inductor and capacitor in parallel form create high impedance at the tuned frequency.

The presence of selective or tuned harmonic content are filtered out by the high impedance

filters, hence Series passive filter can be used to filter out a single harmonic order.

Figure 1.2.713 Circuit Diagram of Series-passive filter

The high impedance blocks the flow of harmonic currents at the tuned frequency. The use of

series filters is limited in blocking multiple harmonic currents. Each harmonic current requires a

series filter tuned to the desired harmonic. This arrangement can create significant losses at the

fundamental frequency [49]. The circuit diagram of the series-passive filter is as shown in Figure

1.2.7. The resonant frequency f0 is calculated using the following expression.

f0 = 1

2π√LC (9)

E. Single Tuned Filter:

The most common type of passive filter is a single tuned “notch” filter. The single-tuned (ST)

filters are efficient filters and will bypass a certain harmonic to which these are tuned. These are

most widely used filters in all applications of harmonic mitigation. The notch filter is series-

tuned to create a low impedance to a particular harmonic current and is connected in shunt with

23

the power system. Thus, harmonic currents are diverted from their normal flow path on the line

through the filter [50], [53], [54], [57], [65], [71], [79]–[82], [84]–[86], [91], [95], [96], [102],

[106], [111], [114], [119]–[135] . The circuit diagram of the single tuned filter is as shown in

Figure 1.2.8. The single tuned filter can be designed by resonant frequency f0:

f0 = 1

2π√LC (10)

Where L and C represents inductor and capacitor, while designing the single tuned filter the

inductive reactance XL and capacitive reactance XC should be equal for resonance, XL=XC.

XC= 1

ωC and XL = ωL, where ω= 2πf. f=fundamental frequency.

Figure 1.2.8 Circuit Diagram of Single Tuned filter

F. Double Tuned Filter:

The double tuned filter performs the same function as two single tuned filters connected in

parallel although it has certain advantages of lower cost, low losses and lower impedance

magnitude at the frequency of parallel resonance that arises between the two tuning frequencies.

The double tuned filter consists of a series LC circuit and a parallel LC circuit as shown in

Figure 1.2.9 [9], [50], [53], [54] .

24

Figure 1.2.9. Circuit diagram of Double tuned filter

If f1 and f2 are the two tuning frequencies, both the series circuit and parallel circuit are tuned to

approximately the mean geometric frequency (fm) given by the relation fm = √f1 f

2 , resonant

frequency fm calculated as follows:

fm = 1

2π√LC (11)

G. Common-mode filter:

Common mode voltage in power converters and power inverters introduces many problems to

power electrical systems. This common mode voltage can interfere with nearby systems and can

disturb the performance. The inverter produces the common mode voltage and it passes through

all the components in the circuit and degrades the performance. In order to reduce this common

mode voltage, a common mode filter is used to prevent these common mode voltages. Common

mode voltage exists between the load neutral, common noise voltage flows in the same direction

on both power conductors and returns via the ground conductor and can be suppressed by the use

of inductors. These common mode voltages create EMI noise and can disturb the motor.

Common mode filters are used to suppress common mode noise. This type of filter is designed

by using inductors, capacitors, and resistors. Since common mode voltage flow through the filter,

the filter works as inductor against the common mode current. A common mode filter provides

larger impedance against common mode current and common mode filter more effective for

common mode noise suppression than using several normal inductors [136]–[140]. The circuit

diagram of common-mode filters are as shown in Figure 1.3.

25

Figure 1.3. Circuit diagram of Common-mode Filter

1.2.1 Thermal Model, Design of Induction Motor

Most of the failures in induction motors and its parts are mainly from motor overheating, thermal

stress potentially causes the failure of all the major motor parts, the stator, rotor, bearings, shaft

and frame. Stator winding insulation breakdown due to excessive thermal stress is one of the

major causes of electric machine failures, therefore prevention of such a failure is crucial for

increasing machine reliability and minimizing financial loss due to motor failure. Statistics have

shown that despite their reliability and construction simplicity, the motor failure rate is

conservatively estimated at 3-5% per year, and in extreme cases, up to 12% of motors were

failed in pulp and paper industry [136]. It is depends upon kind of surge, spikes and disturbances

in power supply results in additional power losses in the induction motor, the higher winding

temperature causes faster aging of the insulation system and shortens the operational life time of

the induction motor. The reduction of the lifetime in the windings due to excess temperature is

observed in marine ships because of harmonics [137]. Researchers focus on the development of

an efficient and reliable stator winding temperature estimation scheme for small to medium size

induction machines. The motivation for the stator winding temperature estimation is to provide

an accurate temperature estimate that is capable of monitoring the stand by temperature threshold

of the induction motor. The thermal design should make sure that the motor windings

temperatures do not exceed the limit for the insulation class, in the worst situation. Heat removal

and the temperature distribution within the induction motor are the two major objectives of

thermal design. Finding the highest winding temperature spots is crucial to insulation (and

machine) working life. The heat transfer in an induction motor depends on the level and location

26

of losses and machine geometry. Insulation lifetime decreases by half of motor operating

temperature exceed thermal limit by 10ºC for any period of time. Figure 1.3.1 shows the graph of

working life hours vs. temperature of the various class of induction motor, hence as the

temperature increases lifetime decreases [138] [136], [139]–[141] [142]–[159] . Calculating the

predicted temperature rise of windings helps in thermal distribution of induction motor, predicted

temperature is calculated by developing the thermal model and thermal resistance is determined

by constructed thermal network of an induction motor.

Each element in the motor corresponds to a node in a thermal network, the thermal resistance

between the elements in a real machine corresponds to the resistance between the nodes in the

network, and the thermal capacitances of different parts of the machine are modelled with

capacitance connected to the nodes.

Figure 1.3.1 Life hours vs. temperature of various class of motors

Heat flow in the machine corresponds to the currents between the nodes and the current sources

in the network, respectively. Prediction of temperature rise in the induction motor helps in

ensuring the maximum withstanding temperature of the induction motor.

27

CHAPTER II

FIVE PHASE INVERTER

This chapter explains the construction and working of five phase inverter drive using

Simulink/MATLAB and experimental study of five phase induction motor drive. The Harmonics

and THD are measured both in simulation and experimentally, temperature is measured using j-

type thermocouples placed at various parts of the five phase induction motor. The five phase

induction motor drive is operated at low speed according to V/F profile with full torque load.

2.1. Circuit diagram and Working

The circuit diagram of five phase induction motor drive or normal drive is as shown in

Figure 2.1.1.

Figure 2.1.14Circuit diagram of Five phase induction motor drive

Circuit constructed with 10 MOSFETs (IRF840), and the gate control signals are

generated using microcontroller kit which are connected to the gate terminal of the MOSFETs.

The switching sequence of the five phase is as shown in Figure 2.1.2. Switches P1 – P10 are

conducting for a period of 180º with a phase shift of 72º with each other.

28

Figure 2.1.15 Switching Sequence of Five phase Inverter for one compete cycle

The five phase lines are represented by A, B, C, D, E and A', B', C', D', E' represents its

compliments, there are 10 working modes in this switching pattern. The pattern of switching can

be described as two switches from upper group and three switches from lower group are on and

vice versa, to produce the PWM AC voltage at the output of the inverter. The individual phase

voltages with respect to neutral can be calculated using the equivalent circuit shown in Figure

2.1.3. The topology of FPI from mode 1 to mode 10 is as follows.

29

Figure 2.1.16 Equivalent circuit diagram of five phase inverter with R loads

The 1st mode the switches P1P3P5P7P8 conducts and the five-phase voltage generated to

drive the five-phase induction motor, The equivalent resistance Req can be obtained from the

Figure 2.1.3, where R1=R2=R3=R4=R5=R, then

Req= R

3+

R

2=

6R

5 (12)

Current, i= 6VDC

Req

= 6VDC

5R (13)

Phase voltages,

30

VAN=VDN=VEN= iR

3 (14)

Substituting i, therefore

VAN=VDN=VEN=2VDC

5 (15)

Phase voltages,

VBN=VCN=-iR

2= -

3VDC

5 (16)

Continuation of these steps up to Mode 10 the resultant individual five phase voltages

with respect to neutral are represented in the Table 2.1.1.

Table 2.1.1 Individual five phase voltage from Mode 1 to 10

Mode Conducting

Switches

Phase Voltages with respect to Neutral (V)

VAN VBN VCN VDN VEN

1 P1P4P5P7P8 +2/5VDC - 3/5VDC -3/5VDC +2/5VDC +2/5VDC

2 P1P5P7P8P9 +3/5VDC - 2/5VDC - 2/5VDC - 2/5VDC +3/5VDC

3 P1P2P5P8P9 +2/5VDC +2/5VDC - 3/5VDC - 3/5VDC - 3/5VDC

4 P1P2P8P9P10 +3/5VDC +3/5VDC - 2/5VDC - 2/5VDC - 2/5VDC

5 P1P2P3P9P10 +2/5VDC +2/5VDC +2/5VDC - 3/5VDC - 3/5VDC

6 P2P3P6P9P10 - 2/5VDC +3/5VDC +3/5VDC - 2/5VDC - 2/5VDC

7 P2P3P4P6P10 - 3/5VDC +2/5VDC +2/5VDC +2/5VDC - 3/5VDC

8 P3P4P6P7P10 - 2/5VDC - 2/5VDC +3/5VDC +3/5VDC - 2/5VDC

9 P3P4P5P6P7 - 3/5VDC - 3/5VDC +2/5VDC +2/5VDC +2/5VDC

10 P4P5P6P7P8 - 2/5VDC - 2/5VDC +3/5VDC +3/5VDC - 2/5VDC

2.2 Simulation Results

Simulink/MATLAB is a software tool is used to construct power circuits and.

Five phase inverter drive is constructed with RL load using Simulink/MATLAB as shown in

Figure 2.2.1. Control signals are generated using Pulse generator blocks P1 to P10 which are

connected to MOSFETs S1 to S10 and input frequency is varied using pulse generator blocks.

Inputs are initialized according to v/f profile of the five phase induction motor, the results are

obtained for two v/f profile 20V/5Hz and 32V/8Hz. The RL load values initialized according to

the measured RL values of the five phase induction motor, the initialized RL values are R=1.7Ω

31

and L=45.7 mH. The output voltage and current waveform of the phase A is obtained as shown

in Figure 2.2.2.

Figure 2.2.1 Construction of five phase inverter drive using Simulink/MATLAB

Figure 2.2.2 Simulation Results: Output voltage and current waveform of phase A for an input of 32V/8Hz

2.3 Experimental Results

Five phase induction motor drive is constructed using MOSFETs, voltage and current are

obtained with THD, using WT500 power analyser as shown in Figure 2.3.1. Input

voltage/frequency are initialized according to V/F profile as 32V/8Hz to operate the motor with

low RPM of 232 with full torque load of 0.13Nm. The temperature is measured for two different

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-0.4

-0.2

0

0.2

0.4

0.6

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-20

-10

0

10

20

Time (Sec)

Output Voltage

Time (Sec)

Voltage (V)

Current (A)

32

V/F profiles. The V/F profile of 20V/5Hz and 32V/8Hz, with a full torque load of 0.13Nm is

adopted to study the temperature of induction motor experimentally. The temperature at various

parts of the five phase induction motor is measured using temperature module kit and results are

recorded as shown in Figure 2.3.2 and Figure 2.3.3.

Figure 2.3.1 Output voltage and current waveform of phase A for an input of 32V/8Hz

Figure 2.3.2 Temperature vs. time graph of various parts of five phase induction motor for an input of 32V/8Hz, full torque load

of 0.13Nm

33

Figure 2.3.3 Temperature vs. time graph of various parts of five phase induction motor for an input of 20V/5Hz, full torque load

of 0.13Nm

Table 2.3.1 shows the maximum temperature obtained at various parts of the induction

motor for an input of 20V/5Hz and 32V/8Hz at full torque load of 0.13Nm

Table 2.3.1Maximum temperature at various parts of the induction motor for a full torque load of 0.13Nm

Induction Motor Parts 20V/5Hz (ºC) 32V/8Hz (ºC)

Stator Winding 1 36.07 41.4

Stator Winding 2 35.57 41.04

Inner Frame 1 34.89 39.14

Inner Frame 2 34.53 36.36

Bearings 34.27 39.11

Body 33.39 37.83

Room Temperature 27.68 26.89

2.4 Comparison

The temperature at various parts of the induction motor is compared with the predicted

temperature obtained by thermal analysis experimentally, for two input profiles 20V/5Hz and

32V/8Hz as shown in Table 2.4.1.

34

Table 2.4.1 Comparison of experimental and predicted temperature of five phase induction motor for a torque load of 0.13Nm

Induction

Motor Parts

20V/5Hz 32V/8Hz

Experimental

Measured

Temperature

(ºC)

Predicted

Temperature

(ºC)

Experimentally

Measured

temperature (ºC)

Predicted

Temperature

(ºC)

Stator

Winding 1 36.07 36.14 41.4 41.1

Stator

Winding 2 35.57 36.14 41.04 41.1

Inner Frame 1 34.89 33.93 39.14 36.08

Inner Frame 2 34.53 33.93 36.36 36.08

Body 33.3 33.02 37.83 34.84

2.5 Conclusion

A normal Five phase inverter drive is constructed using Simulink/MATLAB. The motor

has been run for a duration of 4 hours to measure the temperature, The maximum temperature

obtained is compared with the predicted temperature, it is found that rate of rise of temperature

in five phase induction motor drive and predicted temperature are approximately same. Hence it

is concluded that the temperature at various parts of five phase motor is same with the predicted

temperature obtained by thermal analysis.

35

CHAPTER III

HARMONIC ANALYSIS OF FIVE PHASE INVERTER

3.1 Harmonic Analysis

Simulation: Harmonic analysis and THD of Five phase inverter drive is studied using

simulation, the results are obtained for two v/f profile 20V/5Hz and 32V/8Hz. The output voltage

and current waveform of the phase A is used for FFT analysis in Simulink/MATLAB. The

harmonics and THD are measured for an input voltage/frequency of 32V/8Hz the THD obtained

is presented in the bar graph as shown in Figure 3.1.1.

Figure 3.1.1 Simulation Results: FFT analysis of output voltage of phase A for an input of 32V/8Hz

Experimental:

Harmonics are obtained with THD, using WT500 power analyser for the five phase

induction motor drive as shown in Figure 3.1.2. Table 3.1.1 shows the Total Harmonic Distortion

and Table 3.1.2 shows the individual harmonic order percentage of five phase induction motor

drive for an input profile of 20V/5Hz and 32V/8Hz at full torque load of 0.13Nm.

36

Figure 3.1.2 FFT analysis of output voltage for an input of 32V/8Hz

Table 3.1.1Total Harmonic Distortion of five phase induction motor drive for a full torque load of 0.13Nm

Operating input

voltage/frequency

profile

THD (%)

20V/5Hz 43.02

32V/8Hz 43.03

Table 3.1.2 Individual harmonic order percentage of five phase induction motor drive for a full torque load of 0.13Nm

Harmonic Order 32V/8Hz

Fundamentals (%)

20V/5Hz

Fundamentals (%)

1 96.69 96.81

2 5.35 5.13

3 30.08 30.05

4 2.80 7.22

5 4.00 7.57

6 2.64 8.72

7 6.83 13.94

8 0.56 8.03

9 12.83 11.94

10 2.16 8.67

11 13.17 12.54

12 18.48 17.63

13 8.53 0.93

14 17.11 16.20

15 5.07 6.65

37

3.2 Conclusion

A normal Five phase inverter drive is constructed using Simulink/MATLAB. The

harmonics and THD are measured using FFT analysis using MATLAB, it is found that THD

obtained for the normal drive is 43%. The work has been extended to the impact of harmonics

and THD Experimentally on five phase induction motor. Harmonics and THD are measured

experimentally using WT500 Power analyser, it is found that the maximum THD is 43% in

normal drive of five phase induction motor.

38

CHAPTER IV

Harmonic effects and Temperature analysis of five phase

induction motor with various filters

This chapter explains reduction of harmonics and Total Harmonic Distortion (THD) in

the five phase inverter drive with various filters using Simulink/MATLAB. Using FFT analysis

tool box, harmonics and THD are measured and compared with and without filters. The work is

extended to study five phase induction motor drive with various filter experimentally. The

harmonics and THD are measured using WT500 power analyser, the temperature is measured

at various parts of the induction motor for a duration of 4 hours at low speed with the input

profile voltage/frequency of 20V/5Hz and 32V/8Hz with a torque load of 0.13Nm. The effects of

harmonics on motor temperature is studied and rate of rise of temperature is reduced using

various filter.

4.1.1 LC filter

A. Simulation work:

The circuit diagram of five phase inverter drive with LC filter is constructed as shown in

Figure 4.1.1. The LC filter is used at the output five phase PWM Inverter drive for minimizing

harmonics and THD. The filter is designed and connected at each phase with the resonant

frequency (fR). The resonant frequency can be calculated using the formula

fR=

1

2π√LC (Hz) (17)

39

Figure 4.1.17 Circuit diagram of five phase inverter drive with LC filter

To remove the dominant harmonics and also higher order harmonics, the filter LC is

designed for the resonance frequency. For an input profile of 20V/5Hz the 3rd harmonic

frequency is 15 Hz and for 32V/8Hz the 3rd harmonic frequency is 24 Hz. Hence for better

reduction of harmonics fR is designed for 14 Hz, by keeping C as 1000µF the calculated values of

inductor L are 129mH therefore C1 to C5 is 1000 µF and L1 to L5 is 129mH. Similarly for 32V/8

Hz the fR is designed 23Hz, the calculated value of inductor L is 47mH. The output voltage and

current waveform of phase A is as shown in Figure 4.1.2. Figure 4.1.3 shows FFT analysis of

output voltage of phase A using Simulink.

Figure 4.1.18 Simulation Results: Output voltage and current waveform of phase A of five phase inverter with LC filter with an

input voltage/frequency of 32V/8Hz

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5-10

-5

0

5

10

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5-0.04

-0.02

0

0.02

0.04

0.06

0.08

Time (Sec)

Voltage (V)

Current (A)

TIme (Sec)

40

Figure 4.1.19. Simulation Results: FFT analysis of output voltage of five phase inverter with LC filter with an input

voltage/frequency of 32V/8Hz

B. Experimental Work:

Figure 4.1.4 shows the circuit diagram of five phase induction motor drive with LC filter.

Figure 4.1.4 Circuit diagram of five phase induction motor drive with LC filter

LC filter will offers a near zero impedance channel for the tuned resonant frequency.

While designing the filters, it is mandatory to monitor maximum current ripple from the inverter

due to switching action. Inductance is depends on the maximum ripple current of the inverter and

capacitance value is depends on the inverter’s voltage ripple from the switching action of the

switches used in the inverter. These shunt type filters create low impedance lane for harmonic

content which attracts the harmonics from the systems. Capacitor behaves as a low impedance

41

point where higher order harmonics and higher frequency will be absorbed. The five phase

induction motor drive is operated with two input voltage/frequency profile 32V/8Hz and

20V/5Hz with full torque load of 0.13Nm. The LC filter design for resonant frequency with the

inductors L1 –L5 = 47mH and capacitors C2 –C6 = 1000µF is used for the input

voltage/frequency profile 32V/8Hz. Similarly for the input voltage/frequency 20V/5Hz, the

resonant frequency is designed with the inductor and capacitor values are L1 –L5 = 129mH and

C2 –C6 = 1000µF, the same is implemented experimentally. The output voltage and current

waveform of the phase A of five phase induction motor drive is as shown in Figure 4.1.5.

Figure 4.1.5 Output voltage and current waveform of phase A of five phase induction motor drive with LC filter for input

voltage/frequency of 32V/8Hz, torque load of 0.13Nm

Harmonics and THD are measured using FFT analysis using WT500 Power analyser as

shown in Figure 4.1.6. The temperature at various parts of the five phase induction motor are

measured for input voltage/frequency 32V/8Hz and 20V/5Hz as shown in Figure 4.1.7 and

Figure 4.1.8 respectively. Table 4.1.1 presents the maximum temperature obtained for the five

phase induction motor drive with LC filter for both input voltage/frequency profile.

42

Figure 4.1.6 FFT analysis of output voltage of five phase induction motor drive with LC filter for input voltage/frequency of

32V/8Hz, torque load of 0.13Nm obtained using WT500 power analyser

Figure 4.1.7 Measurement of temperature of various parts of five phase induction motor drive with LC filter for input

voltage/frequency of 32V/8Hz, torque load of 0.13Nm

43

Figure 4.1.8 Measurement of temperature at various parts of five phase induction motor drive with LC filter for input

voltage/frequency of 20V/5Hz, torque load of 0.13Nm

Table 4.1.3Maximum temperature obtained at various parts of the five phase induction motor drive with a torque load of 0.13Nm

Induction Motor

parts

Max. Temperature

20V/5Hz (ºC)

Max. Temperature

32V/8Hz (ºC)

Stator Winding 1 30.69 34.83

Stator Winding 2 30.59 34.53

Inner Frame 1 30.17 33.75

Inner Frame 2 29.86 33.15

Bearings 29.25 33.65

Body 29.72 32.88

Room Temperature 26.17 26.53

C. Comparison

The harmonic and temperature analysis five phase induction motor drive is studied with

and without LC filter for two input voltage/frequency profiles with full load torque, the results

obtained are compared and presented. The harmonic analysis with and without filter is presented

in the Figure 4.1.9. The individual harmonics with and without filter is obtained and presented in

the Table 4.1.2, and comparison of THD is presented in Table 4.1.3. The table 4.2.4 presents the

44

comparison of temperature at various parts of normal five phase induction motor drive, with LC

filter and with predicted temperature.

Figure 4.1.9 Harmonic comparison of five phase induction motor normal drive and with LC filter for an input voltage/frequency

of 32V/8Hz, with a torque load of 0.13Nm

Table 4.1.4 Comparison of individual harmonic orders of five phase induction motor drive without and with LC filter, torque

load of 0.13Nm the results are obtained using WT500 power analyser

Harmonic

Order

32V/8Hz 20V/5Hz

Normal Drive

Harmonics

(%)

LC filter

Harmonics

(%)

Normal Drive

Harmonics

(%)

LC filter

Harmonics

(%)

1 96.69 97.65 96.81 97.19

2 5.35 1.35 4.21 0.81

3 30.08 18.30 30.05 16.92

4 2.8 0.71 7.72 3.09

5 4 3.17 8.30 2.1

6 2.64 0.90 8.12 1.85

7 6.83 5.71 12.73 4.86

8 0.56 0.47 9.01 1.02

9 12.83 2.87 5.09 0.51

45

10 2.16 2.20 8.61 1.14

11 13.17 3.26 5.73 4.55

12 18.48 3.96 4.36 0.63

13 8.53 1.63 6.06 1.1

14 17.11 5.04 5.60 0.59

15 5.07 2.75 2.64 0.28

Table 4.1.3 Comparison of THD of five phase inverter drives

Study Input V/f Modes THD

(%)

Simulation

Work

32V/8Hz Five phase Inverter drive (Without Filter) 43

Five phase Inverter drive With LC Filter 20.48

20V/5Hz Five phase Inverter drive (Without Filter) 43

Five phase Inverter drive With LC Filter 20.65

Experimental

Work

32V/8Hz

Five phase induction motor drive (Without

Filter)

43

Five phase induction motor drive With LC Filter 21.57

20V/5Hz

Five phase induction motor drive (Without

Filter)

43

Five phase induction motor drive With LC Filter 21.76

Table 4.1.4 Comparison of temperature at various parts of the five phase induction motor drives with a torque load of 0.13Nm

Induction Motor

Parts

20V/5Hz 32V/8Hz

Normal

Drive

(ºC)

Predicted

temperature

(ºC)

With

LC

filter

(ºC)

Normal

Drive

(ºC)

Predicted

temperature

(ºC)

With

LC

filter

(ºC)

Stator Winding 1 36.07 36.14 30.69 41.4 41.1 34.83

Stator Winding 2 35.57 36.14 30.59 41.04 41.1 34.53

Inner Frame 1 34.89 33.93 30.17 39.14 36.08 33.75

Inner Frame 2 34.53 33.93 29.86 36.36 36.08 33.15

Body 33.3 33.02 29.72 37.83 34.84 32.88

46

4.2.1 LCL filter

A simulation work has been carried out using LCL filter, this methodology gives better

attenuation of harmonics in the PWM inverter than the L, LC and π filters. Major advantages of

the LCL-filter are that it gives low distortion in output current and low distortion in reactive

output power. The Circuit diagram of five phase inverter drive with LCL filter is as shown in

Figure 4.2.1.

Figure 4.2.1 Circuit diagram of five phase inverter drive with LCL filter

The resonant frequency fR of the LCL-filter is given by:

fR=

1

2π√

L1+L2

L1L2C (Hz) (33)

To remove dominant 3rd order and higher order frequency harmonic component the

resonant frequency is designed for 14Hz, considering input frequency as 5 Hz. Similarly for

input frequency of 8Hz the resonant frequency fR is 23Hz, Therefore for voltage/frequency of

32V/8Hz, the designed parameter values are L1=L2=47mH, keeping C as 1000µF. Figure 4.2.2

shows the output voltage and current waveforms of five phase inverter drive with LCL filter.

47

Figure 4.2.2. Simulation results: Output voltage and current waveform of phase A of five phase inverter drive with LCL filter

with an input v/f of 32V/8Hz,

Figure 4.2.3 shows the FFT analysis of output voltage of five phase inverter drive using

simulink/Matlab.

Figure 4.2.3 Simulation results: FFT analysis of output voltage of Five phase inverter drive with LCL filter with an input v/f of

32V/8Hz

B. Experimental work

The circuit diagram of five phase induction motor drive with LCL filter is constructed

with 10 MOSFET’s as shown in Figure 4.2.4.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-6

-4

-2

0

2

4

6

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-0.05

0

0.05

0.1

Time (Sec)

Voltage (V)

Current (A)

Time (Sec)

48

Figure 4.2.4 Circuit diagram of five phase induction motor drive with LCL filter

Five phase induction motor drive is operated with 2 input voltage/frequency profile of

32V/8Hz and 20V/5Hz. For the input v/f profile of 32V/8Hz, the filter is designed with the

inductors L1-L10 = 47mH and capacitor C2 – C6= 1000µF. Similarly for 20V/5Hz, the calculated

values of inductors L1-L10=129mH and capacitor C2 – C6= 1000µF. The harmonics, THD is

measured with a torque load of 0.13Nm using Power analyzer WT500. Figure 4.2.5 shows the

output voltage and current waveform of phase A of five phase induction motor with LCL filter.

Figure 4.2.6 shows the FFT analysis of the output voltage of five phase induction motor drive

with LCL filter.

Figure 4.2.5 Output voltage and current waveforms of phase A of five phase induction motor drive with LCL filter for the input

v/f of 32V/8Hz, torque load of 0.13Nm

49

Figure 4.2.6 FFT analysis of output voltage of five phase induction motor drive with LCL filter for the input v/f of 32V/8Hz,

torque load of 0.13Nm

The improvement of harmonic and THD reduction is observed experimentally and the

same is extended to study the temperature analysis of five phase induction motor drive. The

Figure 4.2.7 and Figure 4.2.8 depicts the measurement of temperature at various parts of the five

phase induction motor drive with LCL filter at low speed for the input v/f of 32V/8Hz and

20V/5Hz respectively.

Figure 4.2.7 Measurement of temperature at various parts of five phase induction motor with LCL filter with input v/f of

32V/8Hz, torque load of 0.13Nm

50

Figure 4.2.8 Measurement of temperature at various parts of five phase induction motor with LCL filter with input v/f of

20V/5Hz, torque load of 0.13Nm

The experimental study is done for five phase induction motor drive, the maximum

temperature obtained at various parts of the five phase induction motor at low speed is presented

in table 4.2.1.

Table 4.2.1 Maximum temperature obtained at various parts of five phase induction motor with a torque load of 0.13Nm

Induction Motor parts v/f profile

32V/8Hz (ºC)

v/f profile

20V/5Hz (ºC)

Stator Winding 1 37.54 34.19

Stator Winding 2 36.87 34.83

Inner Frame 1 36.59 34.26

Inner Frame 2 35.33 33.76

Bearings 35.20 33.55

Body 35.52 33.33

Room Temperature 26.57 27.02

C. Comparison

The harmonics and THD are compared between the five phase induction motor (Normal)

drive and with five phase induction motor with LCL filter with an input v/f of 32V/8Hz and

51

20V/5Hz. The results are presented in Figure 4.2.9, the bar graph gives the individual harmonics

content with normal five phase inverter drive and with LCL filter.

Figure 4.2.9 Harmonics comparison of normal five phase induction motor drive and with LCL filter with input v/f of 32V/8Hz,

torque load of 0.13Nm

The Table 4.2.2 and Table 4.2.3 shows the individual harmonic order and THD comparison

between the normal drive and with LCL filter respectively. Table 4.2.4 shows the temperature

comparison of normal drive, with LCL filter and with predicted temperature obtained by DC

analysis.

Table 4.2.2 Comparison of individual harmonic orders of five phase induction motor drive without and with LCL filter, torque

load of 0.13Nm

Harmonic

Order

v/f profile 32V/8Hz v/f profile20V/5Hz

Normal

Drive

Harmonics

(%)

LCL filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

LCL filter

Harmonics (%)

1 96.69 98.11 96.81 97.10

2 5.35 0.85 4.21 0.68

3 30.08 18.30 30.05 20.50

4 2.80 2.37 7.72 1.33

5 4.02 2.51 8.30 2.91

52

6 2.64 2.90 8.12 1.91

7 6.83 4.14 12.73 3.87

8 0.56 2.40 9.01 1.96

9 12.83 2.61 5.09 3.53

10 2.16 2.17 8.61 0.36

11 13.17 2.04 5.73 4.67

12 18.48 1.48 4.36 0.84

13 8.53 2.66 6.06 1.53

14 17.11 1.06 5.60 1.99

15 5.07 1.93 2.64 0.73

Table 4.2.3 Comparison of THD of five phase induction motor drives, with a torque load of 0.13Nm

Study Input V/f Modes THD

(%)

Simulation

Work

32V/8Hz Five phase Inverter drive (Without Filter) 43.03

Five phase Inverter drive With LCL Filter 28.48

20V/5Hz Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With LCL Filter 29.23

Experimental

Work

32V/8Hz Five phase induction motor drive (Without Filter) 43.00

Five phase induction motor drive With LCL Filter 33.70

20V/5Hz Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With LCL Filter 33.70

Table 4.2.4 Comparison of temperature at various parts of the five phase induction motor drive with torque load of 0.13Nm.

Induction Motor

Parts

v/f profile 20V/5Hz v/f profile 32V/8Hz

Normal

Drive

(ºC)

Predicted

temperature

(ºC)

With

LCL

filter (ºC)

Normal

Drive

(ºC)

Predicted

temperature

(ºC)

With

LCL

filter (ºC)

Stator Winding 1 36.07 36.14 34.19 41.40 41.10 37.54

Stator Winding 2 35.57 36.14 34.83 41.04 41.10 36.87

Inner Frame 1 34.89 33.93 34.26 39.14 36.08 36.59

Inner Frame 2 34.53 33.93 33.76 36.36 36.08 35.33

Body 33.30 33.02 33.33 37.83 34.84 35.52

53

4.3.1. π filter

A. Simulation Work

The construction of five phase inverter drive with π filter is as shown in Figure 4.3.1.

Figure 4.3.1 Circuit diagram of five phase inverter drive with π filter

The π filter is constructed with an inductor and 2 capacitors, one capacitor acts as a shunt

capacitor and other acts as a bypass capacitor, the inductor L is use for high reactance to the

inverter output AC voltage.

The resonant frequency fR is calculated using the relation

fR=

1

2π√LC (Hz) (34)

For an input v/f profile of 20V/5Hz, fR is designed for 14 Hz, keeping C as 1000µF the

calculated values of inductor L is 129mH, therefore C1 to C10 is 1000µF and L1 to L5 is 129mH.

Similarly for v/f profile of 28V/7Hz, fR is designed to 21Hz, the capacitors C1 to C10 is 1000µF

and L1 to L5 is 63mH, similarly for v/f profile 32V/8Hz, fR is designed to 23Hz, the capacitors are

C1 to C10 is 1000µF and L1 to L5 is 47mH. The simulation results are obtained with designed

frequencies for the output voltage and current waveform of five phase inverter drive with π filter

is as shown in the Figure 4.3.2. Figure 4.3.3 shows the FFT analysis of output voltage of five

phase inverter with π filter.

54

Figure 4.3.2. Simulation Results: Output voltage and current of phase A of five phase inverter drive using π filter with an input

v/f of 32V/8Hz

Figure 4.3.3 Simulation Results: FFT analysis of five phase inverter with π filter with an input v/f profile 32V/8Hz

B. Experimental Work

The study of harmonics and THD of Five phase inverter drive is constructed

experimentally using π filter is as shown in Figure 4.3.4.

0 0.5 1 1.5 2 2.5-40

-20

0

20

40

Voltage (

V)

0 0.5 1 1.5 2 2.5-1

-0.5

0

0.5

1

Time (Sec)

Curr

ent

(A)

Time (Sec)

55

Figure 4.3.4 Circuit diagram of five phase induction motor drive with π filter

The π filter acts as a low impedance network and attracts harmonic content from the

inverter before coupling to the induction motor. C11 is input capacitor to remove any ripple from

DC content. The experiment is repeated with designed π filter, the output voltage and current

waveform of five phase induction motor drive with π filter is obtained and presented in Figure

4.3.5. The Figure 4.3.6 shows the FFT analysis of five phase induction motor drive with π filter.

Figure 4.3.5 Output voltage and current waveform of five phase induction motor drive with π filter for input v/f of 32V/8Hz with a

torque load of 0.13Nm

56

Figure 4.3.6 FFT analysis of output voltage of five phase induction motor drive with π filter for input v/f of 32V/8Hz with a

torque load of 0.13Nm

The minimization of harmonics and THD is observed experimentally using π filter, and

the work is extended to measure the temperature of five phase induction motor. Figure 4.3.7,

4.3.8 and 4.3.9 shows the temperature obtained at various parts of five phase induction motor for

3 input v/f profiles of 32V/8Hz, 28V/7Hz and 20V/5Hz with a torque load of 0.13Nm

respectively.

Figure 4.3.7 Measurement of temperature at various parts of five phase induction motor drive with π filter for input v/f of

32V/8Hz with a torque load of 0.13Nm

57

Figure 4.3.8 Measurement of temperature at various parts of five phase induction motor drive with π filter for input profile of

28V/7Hz with a torque load of 0.13Nm

Figure 4.3.9 Measurement of temperature at various parts of five phase induction motor drive with π filter for input v/f of

20V/5Hz with a torque load of 0.13Nm

58

Table 4.3.1 shows the maximum temperature obtained at various parts of five phase induction

motor with π filter.

Table 4.3.5Maximum temperature obtained at various parts of five phase induction motor drive with π filter with a torque load of

0.13Nm

Parts of

Induction Motor

v/f profile

32V/8Hz (ºC)

v/f profile

28V/7Hz (ºC)

v/f profile

20V/5Hz (ºC)

Stator Winding 1 36.36 34.68 33.32

Stator Winding 2 35.77 34.42 33.08

Inner Frame 1 35.81 34.38 33.03

Inner Frame 2 35.56 33.68 32.25

Bearings 35.07 33.28 31.73

Body 34.18 32.17 31.53

Room

Temperature 25.44 27.82 26.59

C. Comparison

Comparison of harmonics between the normal drive and with π filter is as shown in

Figure 4.3.9.i. Individual Harmonic order and THD are compared between the normal five phase

induction motor drive and with π filter as shown in Table 4.3.2 and Table 4.3.3 respectively.

Table 4.3.4 shows the comparison of temperature of normal drive, with π filter and with

predicted temperature.

59

Figure 4.3.9.i Comparison of harmonics of five phase induction motor drive and with π filter for input v/f of 32V/8Hz, torque

load of 0.13Nm

Table 4.3.2 Individual harmonic order comparison of five phase induction motor drive with π filter, torque load of 0.13Nm

Harmonic

Order

v/f profile- 32V/8Hz v/f profile-28V/7Hz v/f profile-20V/5Hz

Normal

Drive

Harmonics

(%)

π filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

π filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

π filter

Harmonics

(%)

1 97.69 96.07 97.81 95.65 97.50 96.17

2 5.35 1.69 4.21 0.97 4.29 0.74

3 30.08 16.22 30.05 17.13 30.69 26.89

4 2.80 1.72 7.72 1.59 7.68 1.64

5 4.02 2.11 8.30 2.93 8.90 2.98

6 2.64 0.84 8.12 1.07 8.15 1.08

7 6.83 5.93 12.73 7.18 12.96 7.42

8 0.56 0.93 9.01 0.95 9.54 0.96

9 12.83 3.71 5.09 3.08 5.64 3.53

10 2.16 1.19 8.61 1.05 8.47 1.34

11 13.17 2.22 5.73 3.92 5.39 3.82

12 18.48 2.19 4.36 1.19 4.97 1.36

13 8.53 1.55 6.06 3.21 6.84 3.51

14 17.11 1.95 5.60 1.02 5.32 1.12

60

15 5.07 0.29 2.64 1.47 2.91 1.65

Table 4.3.3 THD comparison of five phase induction motor drives, with a torque load of 0.13Nm

Study Input v/f

profiles

Modes THD

(%)

Simulation

work

32V/8Hz Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With π filter 20.77

28V/7Hz Five phase Inverter drive (Without Filter) 43.03

Five phase Inverter drive With π filter 20.97

20V/5Hz Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With π filter 21.24

Experimental

Work

32V/8Hz Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With π Filter 27.7

28V/7Hz Five phase induction motor drive (Without Filter) 43.03

Five phase induction motor drive With π Filter 28.19

20V/5Hz Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With π Filter 28.04

Table 4.3.4 Comparison of temperature at various parts of the five phase induction motor drive with torque load of 0.13Nm

Parts of

Induction

Motor

v/f profile 20V/5Hz v/f profile 28V/7Hz

Normal

Drive

(ºC)

Predicted

(ºC)

With

π filter

(ºC)

Normal

Drive

(ºC)

Predicted

(ºC)

With

π filter

(ºC)

Stator

Winding 1

36.07 36.14 33.32 39.58 39.57 34.68

Stator

Winding 2

35.57 36.14 33.08 39.45 39.57 34.42

Inner Frame

1

34.89 33.93 33.03 36.93 35.02 34.38

Inner Frame

2

34.53 33.93 32.25 37.82 35.02 33.68

Body 33.30 33.02 31.53 34.14 35.20 32.17

61

Parts of Induction Motor

v/f profile 32V/8Hz

Normal Drive

(ºC) Predicted (ºC)

With π

filter (ºC)

Stator Winding 1 41.40 41.10 36.39

Stator Winding 2 41.04 41.10 35.77

Inner Frame 1 39.14 36.08 35.81

Inner Frame 2 36.36 36.08 35.56

Body 37.83 34.84 34.18

4.4.1 Series-passive filter

A. Simulation Work:

A series-passive filter is connected in series with the load, the inductor and capacitor are

connected in parallel and tuned at desired frequency. Inductor and capacitor in parallel form

creates high impedance at the tuned frequency. At this tuned frequency, filter blocks the content

of harmonics into the load. The presence of selective or tuned harmonic content are filtered out

by the high impedance filters, hence series passive filter can be used to filter out a single

harmonic order. Figure 4.4.1 shows the circuit diagram of five phase inverter drive with Series-

passive filter. To remove the dominant 3rd order harmonic and higher order harmonics resonant

frequency fR is tuned to 14 Hz, 20Hz and 23 Hz considering the voltage/frequency profiles

20V/5Hz, 28V/7Hz and 32V/8Hz respectively. The inductor and capacitor are calculated using

the formula

fR=

1

2π√LC (Hz) (35)

The calculated values are C1 to C5 is 1000µF and L1 to L5 is 129mH for input v/f profile

of 20V/5Hz. Similarly the calculated values are C1 to C5 is 1000µF and L1 to L5 is 63mH for

input v/f profile of 28V/7Hz and the calculated values are C1 to C5 is 1000µF and L1 to L5 is

47mH for input v/f of 32V/8Hz. Figure 4.4.2 and Figure 4.4.3 shows the output voltage and

current of phase A and FFT analysis of output voltage of five phase inverter with series-passive

filter respectively.

62

Figure 4.4.1 Circuit diagram of five phase inverter with Series-passive filter

Figure 4.4.2 Simulation Results: Output voltage and current of phase A of five phase inverter with Series-passive filter with an

input v/f profile of 32V/8Hz

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2-100

-50

0

50

100Line Voltage

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2-5

0

5

Time (Sec)

Line Current

Time (Sec)

Voltage (V)

Current (A)

63

Figure 4.4.3 Simulation Results: FFT analysis of output voltage of five phase inverter drive with Series-passive filter with an

input v/f profile of 32V/8Hz

B. Experimental Work:

The circuit diagram of five phase induction motor drive with series-passive filter is

constructed experimentally is as shown in Figure 4.4.4. C6 capacitor acts as filter to remove any

ripple content in the DC. The output voltage and current waveforms, harmonics are obtained

using WT500 power analyser as shown in Figure 4.4.5 and 4.4.6 respectively.

Figure 4.4.4 Circuit diagram of five phase induction motor drive with series-passive filter

64

Figure 4.4.5 Output voltage and current waveform of phase A of five phase induction motor drive with Series-passive filter for

input v/f profile of 32V/8Hz with a torque load of 0.13Nm

Figure 4.4.6 FFT analysis of five phase induction motor drive with series-passive filter for input v/f profile of 32V/8Hz with a

torque load of 0.13Nm

The harmonic and THD analysis is extended to study the temperature of five phase

induction motor with series passive filter and the results are presented in Figure 4.4.7, 4.4.8 and

4.4.9 with a torque load of 0.13Nm for the input v/f profiles of 32V/8Hz, 28V/7Hz and 20V/5Hz

respectively.

65

Figure 4.4.7 Measurement of temperature at various parts of five phase induction motor with series-passive filter for input v/f

profile of 32V/8Hz with a torque load of 0.13Nm.

Figure 4.4.8 Measurement of temperature at various parts of five phase induction motor with series-passive filter for input v/f

profile of 28V/7Hz with a torque load of 0.13Nm

66

Table 4.4.1 shows the maximum temperature obtained at various parts of five phase induction

motor with torque load of 0.13Nm, with series passive filter for all the 3 v/f profiles.

Figure 4.4.9 Measurement of temperature at various parts of five phase induction motor with series-passive filter for input v/f

profile of 20V/5Hz with a torque load of 0.13Nm

Table 4.4.1 Maximum temperature obtained at various parts of five phase induction motor drive with series-passive filter with a

torque load of 0.13Nm

Parts of Induction

Motor

v/f profile

32V/8Hz (ºC)

v/f profile

28V/7Hz (ºC)

v/f profile

20V/5Hz (ºC)

Stator Winding 1 36.79 35.3 34.42

Stator Winding 2 36.12 34.92 34.19

Inner Frame 1 35.30 34.31 33.50

Inner Frame 2 32.33 33.09 33.00

Bearings 34.94 34.51 32.03

Body 34.29 33.77 32.65

Room Temperature 26.89 26.14 27.56

C. Comparison

The comparison of harmonics between the normal five phase induction motor drive and

with series-passive filter is as shown in Figure 4.4.9.i. THD of five phase induction motor drive

67

is compared with five phase induction motor drive with series-passive filter for three input v/f

profiles 32V/8Hz, 28V/7Hz and 20V/5Hz with a torque load of 0.13Nm is as shown in Table

4.4.2 abs 4.4.3 respectively. The harmonic and THD analysis is used to study the temperature of

five phase induction motor at various parts and the results are obtained and tabulated in Table

4.4.4, the study is done for normal five phase inverter drive and with series passive filter.

Figure 4.4.9.i Comparison of harmonics of five phase normal drive and with series-passive filter for input v/f profile of 32V/8Hz

with a torque load of 0.13Nm.

Table 4.4.2 comparison of Individual harmonic order of a five phase induction motor drive with series-passive filter, torque load

of 0.13Nm

Harmonic

Order

v/f profile 32V/8Hz v/f profile 28V/7Hz v/f profile 20V/5Hz

Normal

Drive

Harmonics

(%)

Series-

passive

filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

Series-

passive

filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

Single

tuned

filter

Harmonics

(%)

1 97.69 98.43 97.80 96.07 97.96 98.16

2 5.35 1.45 4.21 2.36 5.43 0.87

3 30.6 28.55 30.50 28.50 30.64 28.98

4 2.80 0.90 7.72 1.90 5.43 3.19

5 4.02 2.81 8.30 3.25 4.96 1.95

68

6 2.64 0.76 8.12 0.79 4.96 2.11

7 6.83 3.24 12.73 4.29 10.83 5.57

8 0.56 0.42 9.01 0.87 6.07 0.58

9 12.83 4.35 5.09 4.69 12.43 2.02

10 2.16 0.24 8.61 0.77 4.87 0.91

11 13.17 4.16 5.73 3.42 9.18 4.01

12 18.48 1.99 4.36 2.15 6.80 0.64

13 8.53 2.74 6.06 3.98 6.97 0.73

14 17.11 0.97 5.60 1.27 9.30 0.78

15 5.07 0.41 2.64 0.68 9.02 0.23

Table 4.4.3 THD comparison of five phase induction motor drives, with a torque load of 0.13Nm

Study Input V/f

profiles

Modes THD

(%)

Simulation

work

32V/8Hz

Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With Series-passive

filter

20.78

28V/7Hz

Five phase Inverter drive (Without Filter) 43.03

Five phase Inverter drive With Series-passive

filter

20.97

20V/5Hz

Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With Series-passive

filter

21.56

Experimental

Work

32V/8Hz

Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With Series-

passive Filter

27.70

28V/7Hz

Five phase induction motor drive (Without Filter) 43.03

Five phase induction motor drive With Series-

passive Filter

28.19

20V/5Hz

Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With Series-

passive Filter

27.90

69

Table 4.4.4 Comparison of temperature at various parts of the five phase induction motor drive with torque load of 0.13Nm

Parts of

Induction

Motor

v/f profile 20V/5Hz v/f profile 28V/7Hz

Normal

Drive (ºC)

Predicted

(ºC)

With

Series-

passive

filter (ºC)

Normal

Drive (ºC)

Predicted

(ºC)

With

Series-

passive

filter (ºC)

Stator

Winding 1

36.07 36.14 34.42 39.58 39.57 35.31

Stator

Winding 2

35.57 36.14 34.19 39.45 39.57 34.92

Inner Frame

1

34.89 33.93 33.50 36.93 35.02 34.31

Inner Frame

2

34.53 33.93 33.02 37.82 35.02 33.09

Body 33.30 33.02 32.65 34.14 35.20 33.77

Parts of Induction

Motor

v/f profile 32V/8Hz

Normal Drive (ºC) Predicted (ºC) With Series-

passive filter (ºC)

Stator Winding 1 41.40 41.10 36.79

Stator Winding 2 41.04 41.10 36.12

Inner Frame 1 39.14 36.08 35.30

Inner Frame 2 36.36 36.08 35.33

Body 37.83 34.84 34.29

4.5.1 Common mode filter

A. Simulation Work:

The circuit diagram of five phase inverter with common mode filter is as shown in Figure

4.5.1. Common mode filter is constructed with the capacitors C1-C10 and resistors R1-R10 and

inductors L1-L5. Common filter is connected to each individual leg of the inverter, the filter

doesn’t have any design procedure, and the components used in this work are completely not

70

bulky. The inductors and capacitors can be selected by observing trial and error method for the

reduction of harmonics and THD. The selected inductor and capacitor values are L1-L5 = 47mH,

R1-R5 = 100Ω and C1-C10= 1000µF. The output voltage and current waveform of phase A is as

shown in Figure 4.5.2 and FFT analysis of output voltage is as shown in Figure 4.5.3.

Common mode voltage exists between the load and neutral, common mode noise exist in

the same direction on both power conductors and returns via the ground conductor and can be

suppressed by the use of inductors. These common mode voltages create EMI noise and can

impact on the performance of the motor. This type of filter is designed by using inductors,

capacitors, and resistors. Since common mode voltage exists in the filter circuit, the filter works

as inductor against the common mode current.

Figure 4.5.1 Circuit diagram of five phase inverter drive with common mode filter

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

-40

-20

0

20

40

60

TIme (Sec)

Voltage (

V)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-0.2

-0.1

0

0.1

0.2

Time (Sec)

Curr

ent

(A)

71

Figure 4.5.2 Simulation Results: Output voltage and current waveform of phase A of five phase inverter drive with common mode

filter with an input profile of 32V/8Hz

Figure 4.5.3 Simulation Results: FFT analysis of output voltage of five phase inverter drive with common mode filter with an

input profile of 32V/8Hz

B. Experimental Work

The Experimental study of Five phase induction motor with common mode filter has

been done, circuit diagram of five phase induction motor drive with common mode filter is as

shown in Figure 4.5.4.

Figure 4.5.4 Circuit diagram of five phase induction motor drive with common mode filter

The harmonics and THD has been studied experimentally using Power analyzer WT500,

the results are obtained is as shown in Figure 4.5.5 for the output voltage and current waveform

72

of phase A of five phase induction motor drive with common mode filter. Figure 4.5.6 shows the

FFT analysis of five phase induction motor with common mode filter.

Figure 4.5.5 Output voltage and current waveform of five phase induction motor with common mode filter for input fundamentals

of 32V/8Hz with torque load of 0.13Nm.

Figure 4.5.6 FFT analysis of five phase induction motor drive with common mode filter for input v/f profile of 32V/8Hz with

torque load of 0.13Nm.

The experiment analysis of harmonics and THD has been extended to study the

temperature of five phase induction motor. Figure 4.5.7, 4.5.8 and 4.5.9 shows the measurement

73

of temperature at various parts of five phase induction motor for input v/f profiles of 32V/8Hz,

28V/7Hz and 20V/5Hz respectively.

Figure 4.5.7 Measurement of temperature at various parts of five phase induction motor with common mode filter for input v/f

profile of 32V/8Hz with torque load of 0.13Nm.

Figure 4.5.8 Measurement of temperature at various parts of five phase induction motor with common mode filter for input v/f

profile of 28V/7Hz with torque load of 0.13Nm

74

Table 4.5.1 presents the maximum temperature obtained at various parts of five phase

induction motor with a torque load of 0.13Nm.

Figure 4.5.9 Measurement of temperature at various parts of five phase induction motor with common mode filter for input v/f

profile of 20V/5Hz with torque load of 0.13Nm

Table 4.5.6Maximum temperature obtained at various parts of five phase induction motor drive with common mode filter with

torque load of 0.13Nm

Parts of Induction

Motor

v/f profile

32V/8Hz (ºC)

v/f profile

28V/7Hz (ºC)

v/f profile

20V/5Hz (ºC)

Stator Winding 1 36.66 34.11 31.96

Stator Winding 2 36.35 33.67 32.24

Inner Frame 1 35.68 32.13 31.90

Inner Frame 2 32.96 33.24 31.61

Bearings 35.40 32.09 31.21

Body 34.49 32.29 31.19

Room Temperature 26.83 24.84 27.24

C. Comparison

The experimental results of harmonics and THD of five phase induction motor drive

(normal) is compared with common mode filter for v/f of 32V/8Hz with a torque load of 0.13Nm

as shown in Figure 4.5.9.i. Table 4.5.2 and 4.5.3 presents the comparison of harmonics and THD

75

of five phase induction motor drive with common mode filter for all 3 input v/f trials.

Temperature is compared with normal drive, with common mode filter and with predicted

temperature as shown in Table 4.5.4.

Figure 4.5.9.i Comparison of Harmonics of five phase induction motor drive and with common mode filter for input profile of

32V/8Hz with torque load of 0.13Nm.

Table 4.5.2 Individual harmonic order comparison of five phase induction motor drive with common mode filter, torque load of

0.13Nm

Harmonic

Order

v/f profile 32V/8Hz v/f profile 28V/7Hz v/f profile 20V/5Hz

Normal

Drive

Harmonics

(%)

Common

mode filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

Common

mode filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

Common

mode filter

Harmonics

(%)

1 97.69 98.43 97.8 96.07 97.96 98.16

2 5.35 1.45 4.21 2.36 5.43 0.93

3 30.6 28.55 30.5 28.77 30.64 26.80

4 2.80 0.90 7.72 1.90 5.43 3.15

5 4.02 2.81 8.30 3.25 4.96 2.08

6 2.64 0.76 8.12 0.79 4.96 1.69

7 6.83 3.24 12.73 4.29 10.83 5.15

8 0.56 0.42 9.01 0.87 6.07 1.30

9 12.83 4.35 5.09 4.69 12.43 1.99

76

10 2.16 0.24 8.61 0.77 4.87 1.24

11 13.17 4.16 5.73 3.42 9.18 4.75

12 18.48 1.99 4.36 2.15 6.80 0.57

13 8.53 2.74 6.06 3.98 6.97 1.38

14 17.11 0.97 5.60 1.27 9.30 0.82

15 5.07 0.41 2.64 0.68 9.02 0.40

Table 4.5.3 THD comparison of five phase induction motor drives, with a torque load of 0.13Nm

Study Input V/f

profiles Modes

THD

(%)

Simulation

work

32V/8Hz

Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With Common mode

Filter

34.28

28V/7Hz

Five phase Inverter drive (Without Filter) 43.03

Five phase Inverter drive With Common mode

Filter

34.27

20V/5Hz

Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With Common mode

Filter

34.28

Experimental

Work

32V/8Hz

Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With Common

mode Filter

29.00

28V/7Hz

Five phase induction motor drive (Without Filter) 43.03

Five phase induction motor drive With Common

mode Filter

29.00

20V/5Hz

Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With Common

mode Filter

29.00

77

Table 4.5.4 Comparison of temperature at various parts of the five phase induction motor drive with torque load of 0.13Nm

Parts of

Induction

Motor

v/f profile 20V/5Hz v/f profile 28V/7Hz

Normal

Drive

(ºC)

Predicted

(ºC)

With

Common

mode

filter (ºC)

Normal

Drive

(ºC)

Predicted

(ºC)

With

Common

mode

filter (ºC)

Stator Winding

1

36.07 36.14 31.96 39.58 39.57 34.11

Stator Winding

2

35.57 36.14 32.24 39.45 39.57 33.67

Inner Frame 1 34.89 33.93 31.90 36.93 35.02 32.13

Inner Frame 2 34.53 33.93 31.61 37.82 35.02 33.24

Body 33.30 33.02 31.19 34.14 35.20 32.29

Parts of Induction

Motor

v/f profile 32V/8Hz

Normal Drive

(ºC) Predicted (ºC)

With Common

mode filter (ºC)

Stator Winding 1 41.40 41.10 36.66

Stator Winding 2 41.04 41.10 36.35

Inner Frame 1 39.14 36.08 35.68

Inner Frame 2 36.36 36.08 32.96

Body 37.83 34.84 34.49

4.6.1 Single Tuned Filter

A. Simulation Work:

One of the most common method to eliminate the harmonics and THD in industries are

the single tuned filter. These passive filter provides a low impedance path to harmonic

voltage/current at a particular frequency. Generally to eliminate the particular harmonics such as

3rd, 5th, 7th, 11th, 13th etc. resonant frequency is tuned to these harmonic frequencies. Single tunes

filters are connected between the harmonics source and the load. Single tuned filter creates a low

impedance at particular tuning frequency, which allows fundamental frequency to couple the

load and blocks the tuning harmonic frequency which flows in low impedance path instead of

78

coupling to load. In order to eliminate two or more harmonic orders, two or more single tuned

filters are used and their tuning frequencies is designed to those harmonic frequencies. The

circuit diagram of five phase inverter drive with single tuned filter is as shown in Figure 4.6.1.

Figure 4.6.1 Circuit diagram of five phase inverter drive with single tuned filter

The capacitor and inductor values are designed such that the branch impedance becomes

zero nearby harmonic order frequency, which bypasses that harmonic order. The capacitor

provides reactive power compensation in accordance with total power. While designing the

single tuned filter the inductive reactance XL and capacitive reactance XC should be equal for

resonance, XL=XC.

XC= 1

ωC and XL= ωL, where ω= 2πf. f=tuned frequency.

Five phase inverter drive is implemented with a single tuned filter, which is tuned to

remove dominant 3rd harmonic order. The tuning frequency depends on the input fundamental

frequency, hence for input fundamental frequency of 8Hz, 7Hz and 5 Hz, the dominant 3rd order

frequency is 24 Hz, 21 Hz and 15 Hz respectively. Assuming the capacitor as C1-C5= 1000µF the

inductor is designed to L1-L5 = 47mH, 63mH and 129mH and R1-R5 = 83Ω respectively. Output

voltage and current waveform of phase A obtained using Simulink/MATLAB is as shown in

Figure 4.6.2. FFT analysis of output voltage is as shown in Figure 4.6.3.

79

Figure 4.6.2 Simulation Results: Output voltage and current waveform of phase A of five phase inverter drive with Single tuned

filter with an input fundamental of 32V/8Hz

Figure 4.6.3.Simulation Results: FFT analysis of output voltage of five phase inverter drive with Single tuned filter with an input

fundamentals of 32V/8Hz

B. Experimental Work

Five phase induction motor drive is implemented with a single tuned filter between the

five phase inverter and the five phase induction motor load as shown in Figure 4.6.4. Output

voltage, current, harmonics and THD of five phase induction motor drive with single tuned filter

is obtained is as shown in Figure 4.6.5 and 4.6.6 respectively. Temperature at various parts of

five phase induction motor with single tuned filter is studied with input v/f profiles of 32V/8Hz,

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1-40

-20

0

20

40

Voltage (

V)

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1-20

-10

0

10

20

Time (Sec)

Curr

ent

(A)

Time (Sec)

80

28V/7Hz and 20V/5Hz. The results obtained are presented in the Figure 4.6.7, 4.6.8 and 4.6.9

respectively.

Figure 4.6.4 Experimental Construction of five phase induction motor drive with single tuned filter

Table 4.6.1 depicts the maximum temperature obtained at various parts of the five phase

induction motor drive with Single tuned filter with a torque load of 0.13Nm.

Figure 4.6.5 Output voltage and current waveform of five phase induction motor drive with Single tuned filter for input v/f profile

of 32V/8Hz with torque load of 0.13Nm

81

Figure 4.6.6 FFT analysis of five phase induction motor drive with Single tuned filter for input fundamentals of 32V/8Hz with

torque load of 0.13Nm

Figure 4.6.7 Measurement of temperature of five phase induction motor drive with Single tuned filter for input fundamentals of

32V/8Hz with torque load of 0.13Nm

82

Figure 4.6.8 Measurement of temperature of five phase induction motor drive with Single tuned filter for input fundamentals of

28V/7Hz with torque load of 0.13Nm

Figure 4.6.9 Measurement of temperature of five phase induction motor drive with Single tuned filter for input fundamentals of

20V/5Hz with torque load of 0.13Nm

Table 4.6.7Maximum temperature obtained at various parts of five phase induction motor drive with torque load of 0.13Nm

Parts of Induction v/f profile v/f profile v/f profile

83

Motor 32V/8Hz (ºC) 28V/7Hz (ºC) 20V/5Hz (ºC)

Stator Winding 1 37.8 34.98 33.14

Stator Winding 2 37.63 34.41 32.98

Inner Frame 1 36.9 34.1 32.77

Inner Frame 2 35.98 33.61 32.2

Bearings 35.64 33.25 31.54

Body 35.15 33.09 31.39

Room Temperature 29.34 27.46 26.57

C. Comparison

Comparison of Harmonics between the normal drive and with single tuned filter is as

shown in Figure 4.6.9.i. The Table 4.6.2 presents individual harmonic comparison between the

normal drive and with single tuned filter. Table 4.6.3 shows the THD comparison between the

normal drive and with single tuned filter. Table 4.6.4 shows the temperature comparison of

normal drive, with single tuned filter and with predicted temperature.

Figure 4.6.9.i Comparison of Harmonics of a five phase normal drive and with single tuned filter for input v/f profile of 32V/8Hz

with torque load of 0.13Nm

84

Table 4.6.8 Individual harmonic order comparison of five phase induction motor drives with a torque load of 0.13Nm

Harmonic

Order

v/f profile 32V/8Hz v/f profile 28V/7Hz v/f profile 20V/5Hz

Normal

Drive

Harmonics

(%)

Single

tuned

filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

Single

tuned

filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

Single

tuned

filter

Harmonics

(%)

1 97.69 93.52 97.80 94.35 97.96 95.21

2 5.35 2.18 4.21 2.86 5.43 1.40

3 30.60 22.21 30.50 22.65 30.64 23.09

4 2.80 2.59 7.72 2.90 5.43 3.60

5 4.02 3.02 8.30 4.67 4.96 3.28

6 2.64 7.40 8.12 5.69 4.96 4.57

7 6.83 5.96 12.73 6.37 10.83 7.58

8 0.56 1.86 9.01 1.87 6.07 4.39

9 12.83 3.36 5.09 3.91 12.43 6.14

10 2.16 2.36 8.61 6.57 4.87 3.66

11 13.17 1.90 5.73 2.74 9.18 3.44

12 18.48 2.11 4.36 2.15 6.80 3.00

13 8.53 2.07 6.06 3.70 6.97 2.40

14 17.11 2.33 5.60 3.15 9.30 4.68

15 5.07 3.00 2.64 1.85 9.02 2.61

Table 4.6.3 THD comparison of five phase induction motor drives with a torque load of 0.13Nm

Study

Input

v/f

profiles

Modes THD

(%)

Simulation

work

32V/8Hz Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With Single tuned Filter 28.72

28V/7Hz Five phase Inverter drive (Without Filter) 43.03

Five phase Inverter drive With Single tuned Filter 28.23

20V/5Hz Five phase Inverter drive (Without Filter) 43.02

85

Five phase Inverter drive With Single tuned Filter 28.25

Experimental

Work

32V/8Hz

Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With Single Tuned

Filter

28.40

28V/7Hz

Five phase induction motor drive (Without Filter) 43.03

Five phase induction motor drive With Single Tuned

Filter

28.50

20V/5Hz

Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With Single Tuned

Filter

28.50

Table 4.6.4 Temperature comparison of five phase induction motor drives with a torque load of 0.13Nm

Parts of

Induction

Motor

20V/5Hz 28V/7Hz

Normal

Drive

(ºC)

Predicted

temperature

(ºC)

With

Single

tuned

filter (ºC)

Normal

Drive

(ºC)

Predicted

temperature

(ºC)

With Single

tuned filter

(ºC)

Stator

Winding 1

36.07 36.14 33.14 39.58 39.57 34.98

Stator

Winding 2

35.57 36.14 32.98 39.45 39.57 34.41

Inner Frame

1

34.89 33.93 32.77 36.93 35.02 34.1

Inner Frame

2

34.53 33.93 32.20 37.82 35.02 33.61

Body 33.30 33.02 31.39 34.14 35.20 33.09

Parts of

Induction

Motor

32V/8Hz

Normal Drive

(ºC)

Predicted

temperature (ºC) With Single tuned filter (ºC)

Stator

Winding 1

41.4 41.10 37.80

Stator 41.04 41.10 37.63

86

Winding 2

Inner Frame 1 39.14 36.08 36.90

Inner Frame 2 36.36 36.08 35.98

Body 37.83 34.84 35.15

4.7.1 Double Tuned filter:

A. Simulation Work:

This filter is equivalent to two single tuned filter, the advantage of double tuned filter is

that the power loss at fundamental frequency is less. The double tuned filter consists of a series

LC circuit and a parallel LC circuit capable of tuning two resonant frequencies. If f1 and f2 are

the two tuning frequencies, both the series circuit and parallel circuit are tuned to approximately

the mean geometric frequency (fm) given by the relation fm = √f1 f

2 , at two particular

frequencies the filter creates low impedance and bypasses those particular frequencies. The

inductor parameter is calculated by assuming capacitor as 1000µF, the relation is given by

fm = 1

2π√𝐿𝐶 Hz

For an input v/f profile of 32V/8Hz the two designed frequencies are 24Hz and 56Hz to

remove 3rd and 7th harmonic order respectively. The designed inductor values are L1-L10 =

87mH, capacitors are C2-C11 = 1000µF and resistors are R1-R5 = 67Ω. Similarly for 28V/7Hz the

two designed frequencies are 21Hz and 49Hz, the designed inductors are L1-L10 = 37mH,

capacitors are C2-C11 = 1000µF and resistors are R1-R5 = 67Ω. For 20V/5Hz the two designed

frequencies are 15Hz and 35 Hz, the designed inductors are L1-L10 = 30mH and capacitors are

C2-C11 = 1000µF and resistors are R1-R5 = 67Ω. The circuit diagram of five phase inverter drive

with double tuned filter using Simulink/MATLAB is as shown in Figure 4.7.1. The output

voltage and current waveform of phase A is as shown in Figure 4.7.2 and FFT analysis of output

voltage obtained using Simulink/MATLAB is as shown in Figure 4.7.3.

87

4.7.1 Circuit diagram of five phase inverter drive with double tuned filter

Figure 4.7.2 Simulation Result: Output voltage and current waveform of phase A of five phase inverter drive with double tuned

filter with an input profile of 32V/8Hz

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1-30

-20

-10

0

10

20

30

Time (Sec)

Voltage (

V)

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1-20

-15

-10

-5

0

5

10

15

Time (Sec)

Curr

ent

(A)

88

Figure 4.7.3 Simulation Result: FFT analysis of output voltage of five phase inverter drive with double tuned filter with an input

v/f of 32V/8Hz

B. Experimental Work

The five phase induction motor drive with double tuned filter is constructed

experimentally as shown in Figure 4.7.4. Input v/f profiles are adopted to operate the motor at

low speed is 32V/8Hz, 28V/7Hz and 20V/5Hz with a torque load of 0.13Nm.

Figure 4.7.4 Circuit diagram of five phase induction motor drive with Double tuned filter

The capacitor C1 is an input capacitor acts as filter to remove the ripples form DC

voltage, Figure 4.7.5 shows the output voltage and current waveform of phase A of five phase

89

induction motor drive with double tuned filter for input v/f profile of 32V/8Hz with a torque load

of 0.13Nm. Figure 4.7.6 shows the FFT analysis of output voltage of five phase induction motor

drive with double tuned filter for the input v/f profile of 32V/8Hz with a torque load of 0.13Nm.

Figure 4.7.5 Output voltage and current waveform of phase A for input v/f profile of 32V/8Hz with a torque load of 0.13Nm.

Figure 4.7.6 FFT analysis of five phase induction motor drive with double tuned filter for input v/f profile of 32V/8Hz with a

torque load of 0.13Nm.

Temperature is measured at various parts of five phase induction motor with a torque

load of 0.13Nm for three input v/f profiles 32V/8Hz, 28V/7Hz and 20V/5Hz as shown in Figure

90

4.7.7, 4.7.8 and 4.7.9 respectively. Table 4.7.1 presents the maximum temperature obtained at

various parts of five phase induction motor drive with a torque load of 0.13Nm.

Figure 4.7.7 Measurement of temperature at various parts of five phase induction motor with double tuned filter for an input

profile of 32V/8Hz with a torque load of 0.13Nm

Figure 4.7.8 Measurement of temperature at various parts of five phase induction motor with double tuned filter for an input v/f

profile of 28V/7Hz with a torque load of 0.13Nm

91

Figure 4.7.9 Measurement of temperature at various parts of five phase induction motor with double tuned filter for an input

profile of 20V/5Hz with a torque load of 0.13Nm

Table 4.7.1 Maximum temperature obtained at various parts of five phase induction motor drive with double tuned filter with a

torque load of 0.13Nm

Parts of Induction

Motor

v/f profile

32V/8Hz (ºC)

v/f profile

28V/7Hz (ºC)

v/f profile

20V/5Hz (ºC)

Stator Winding 1 36.20 35.67 31.09

Stator Winding 2 35.96 35.72 31.25

Inner Frame 1 35.56 35.12 30.97

Inner Frame 2 34.27 34.91 30.84

Bearings 35.64 34.91 30.75

Body 34.92 34.25 30.29

Room Temperature 26.43 32.55 26.99

C. Comparison

92

Comparison of harmonics and THD between the normal drive and with double tuned

filter is as shown in Figure 4.7.9.i. The harmonics and THD obtained is compared with normal

five phase induction motor drive and with double tuned filter is as shown in Table 4.7.2 and

Table 4.7.3 respectively. The temperature analysis of normal five phase induction motor is

compared with the double tuned filter and with predicted temperature as shown in Table 4.7.4.

Figure 4.7.9.i Comparison of THD of normal drive and with double tuned filter for input v/f profile of 32V/8Hz with a torque

load of 0.13Nm

Table 4.7.2 Individual harmonic comparison of five phase induction motor drive with double tuned filter with a torque load of

0.13NM

Harmonic

Order

v/f profile 32V/8Hz v/f profile 28V/7Hz v/f profile 20V/5Hz

Normal

Drive

Harmonics

(%)

Double

tuned

filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

Double

tuned

filter

Harmonics

(%)

Normal

Drive

Harmonics

(%)

Double

tuned

filter

Harmonics

(%)

1 97.69 95.74 97.80 96.74 97.96 97.52

2 5.35 1.90 4.21 1.70 5.43 0.34

3 30.60 21.86 30.50 22.86 30.64 18.91

4 2.80 2.31 7.72 1.91 5.43 0.92

5 4.02 2.42 8.30 2.54 4.96 3.17

6 2.64 1.50 8.12 1.40 4.96 0.83

93

7 6.83 6.41 12.73 6.38 10.83 4.97

8 0.56 1.13 9.01 1.29 6.07 0.58

9 12.83 3.69 5.09 4.02 12.43 2.95

10 2.16 0.82 8.61 1.09 4.87 1.01

11 13.17 3.69 5.73 3.77 9.18 2.48

12 18.48 1.50 4.36 1.70 6.80 6.31

13 8.53 0.36 6.06 0.49 6.97 4.74

14 17.11 0.98 5.60 1.10 9.30 3.17

15 5.07 2.60 2.64 2.14 9.02 1.03

Table 4.7.3 THD comparison of five phase induction motor drives with double tuned filter with a torque load of 0.13Nm

Study Input v/f

profiles Modes

THD

(%)

Simulation

work

32V/8Hz Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With Double tuned Filter 28.19

28V/7Hz Five phase Inverter drive (Without Filter) 43.03

Five phase Inverter drive With Double tuned Filter 28.23

20V/5Hz Five phase Inverter drive (Without Filter) 43.02

Five phase Inverter drive With Double tuned Filter 28.25

Experimental

Work

32V/8Hz

Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With Double

Tuned Filter

30.60

28V/7Hz

Five phase induction motor drive (Without Filter) 43.03

Five phase induction motor drive With Double

Tuned Filter

30.50

20V/5Hz

Five phase induction motor drive (Without Filter) 43.02

Five phase induction motor drive With Double

Tuned Filter

30.80

94

Table 4.7.4 Comparison of Temperature of five phase induction motor drives with a torque load of 0.13Nm

Parts of

Induction

Motor

v/f profile 20V/5Hz v/f profile 28V/7Hz

Normal

Drive

(ºC)

Predicted

temperature

(ºC)

With

Double

tuned filter

(ºC)

Normal

Drive

(ºC)

Predicted

(ºC)

With

Double

tuned

filter (ºC)

Stator

Winding 1

36.07 36.14 31.09 39.58 39.57 35.67

Stator

Winding 2

35.57 36.14 31.25 39.45 39.57 35.72

Inner Frame 1 34.89 33.93 30.97 36.93 35.02 35.12

Inner Frame 2 34.53 33.93 30.84 37.82 35.02 34.91

Body 33.30 33.02 30.29 34.14 35.20 34.25

Parts of Induction

Motor

v/f profile 32V/8Hz

Normal Drive

(ºC)

Predicted

(ºC) With Double tuned filter (ºC)

Stator Winding 1 41.40 41.10 36.20

Stator Winding 2 41.04 41.10 35.96

Inner Frame 1 39.14 36.08 35.56

Inner Frame 2 36.36 36.08 34.27

Body 37.83 34.84 34.92

95

Chapter V

CONCLUSION: The “Design and development of speed control of five phase

induction motor with temperature analysis at various parts of the induction motor with

harmonic effects” has been constructed experimentally and studied with simulation, the work

has been carried out as mentioned in the objectives, and all the objectives have achieved

successfully.

Task 1 : Design of speed control of Five phase induction motor

The overall architectural design and techniques have been studied. This task is achieved in two

stages.

a). Generation of Five phase PWM signals generated from Microcontroller to drive Five

phase induction motor.

b). Speed control of Five phase induction motor using Microcontroller, operated at very

low speed.

Task 3. Performance evaluation of the Five-phase induction motor: Operation of five-phase

induction motor experimentally with high torque loads and study of harmonics with and without

filter has been done.

Task 4. Temperature characterization in the stator windings of the Five phase induction

motor: This task involves the temperature measurement in the stator windings of the five phase

and three phase induction motor. This task involves minimization of stator windings of Five-

phase induction motor using filter techniques.

96

97

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