Design and implementation of a 3-phase, 2-Level...

Design and implementation of a

3-phase, 2-Level

Voltage Source Converter

(Using discrete IGBTs)

PEEMD, Research Group, IIT-Delhi

Version V. 1.0 Jun 2017

2

Edition: V. 1.0, June 2017

PEEMD, Research Group,

IIT-Delhi, India.

Legal Disclaimer

The information given in this report is meant for educational and research purpose only.

However, all the data provided is considered non-binding and shall not create liability for us.

All component data referred in this report is subject to further research and development and

therefore, is to be considered exemplary only.

The publisher reserves the right not to be responsible for the accuracy, completeness or

topicality of any direct or indirect reference to or citation from law, regulations or directives

in this publication.

Edited by:

Martin Cheerangal J,

Sritam Jena,

Dr. Anandarup Das,

Faculty & Students of PEEMD Research Group, IIT-Delhi.

3

ABSTRACT

In this report, step by step design of a 2-level, 3-phase Voltage Source Converter (VSC) is

explained. A 10kVA, 415V 3-phase VSC has been designed, fabricated and tested in the labs

in IIT Delhi. The design of VSC constitutes the gate driver circuit, gate pulse divider circuit,

power circuit, rectifier unit including DC-bus capacitor and the heat sink mounting. Every

chapter is included with the schematic diagrams, PCB layouts (with track widths) and bill of

materials (BOM). Detailed pictures of each circuit design and implementation have been

presented in the report.

The report is mainly intended for students and researchers to develop and fabricate a VSC on

their own in the lab.

4

Contents

1 CHAPTER – 1: VOLTAGE SOURCE CONVERTER .................................... 9

1.1 INTRODUCTION ................................................................................................... 9

1.2 VSC SPECIFICATIONS .......................................................................................... 9

1.3 OVERVIEW OF VSC DESIGN ........................................................................... 10

2 CHAPTER – 2: GATE DRIVERS CIRCUIT ................................................. 11

2.1 INTRODUCTION ................................................................................................. 11

2.2 PROTECTIONS IN GATE DRIVER IC ..................................................................... 11

2.2.1 Active miller clamping protection........................................................ 11

2.2.2 Desaturation protection ........................................................................ 11

2.2.3 /Fault, /Reset & Ready pin functions ................................................... 12

2.3 FEATURES OF GATE DRIVER IC .......................................................................... 13

2.4 GATE DRIVER CIRCUIT DESIGN .......................................................................... 14

2.4.1 Boot-strap capacitor & diode rating ..................................................... 14

2.4.2 DESAT capacitor for blanking time ..................................................... 14

2.5 COMPONENTS & BOM ...................................................................................... 14

2.6 PICTURES SHOWING GATE DRIVER BOARD IN VSC ............................................ 17

2.7 PCB LAYOUT OF GATE DRIVER CIRCUIT ............................................................ 18

3 CHAPTER – 3: GATE PULSE DIVIDER CIRCUIT .................................... 21

3.1 INTRODUCTION ................................................................................................. 21

3.2 FUNCTION OF GATE PULSE DIVIDER CIRCUIT ..................................................... 21

3.3 SIGNALS IN AND OUT OF GATE PULSE DIVIDER CIRCUIT ..................................... 22

3.4 PROTECTION CIRCUIT ....................................................................................... 23

3.4.1 Fault protection .................................................................................... 23

3.4.2 Reset function ....................................................................................... 24

3.5 COMPONENTS & BOM ...................................................................................... 24

3.6 PICTURES SHOWINGOF GATE DIVIDER BOARD IN VSC ...................................... 25

3.7 PCB LAYOUT OF GATE DIVIDER CIRCUIT .......................................................... 27

4 CHAPTER – 4: POWER CIRCUIT ................................................................ 29

4.1 INTRODUCTION ................................................................................................. 29

4.2 SIGNALS IN AND OUT OF POWER CIRCUIT .......................................................... 29

5

4.3 COMPONENTS OF POWER CIRCUIT ..................................................................... 30

4.4 COMPONENTS & BOM ...................................................................................... 30

4.5 PICTURES SHOWINGOF POWER CIRCUIT BOARD IN VSC .................................... 31

4.6 PCB LAYOUT OF POWER CIRCUIT ...................................................................... 32

5 CHAPTER– 5: HEAT SINK DESIGN ............................................................. 33

5.1 INTRODUCTION ................................................................................................. 33

5.2 LOSSES IN VSC ................................................................................................. 33

5.2.1 Conduction losses ................................................................................. 33

5.2.2 Switching losses ................................................................................... 35

5.3 PICTURES OF HEAT SINK .................................................................................... 36

6 CHAPTER– 6: RECTIFIER UNIT & DC BUS CAPACITOR ..................... 37

6.1 INTRODUCTION ................................................................................................. 37

6.2 RIPPLE CURRENTS IN CAPACITOR ...................................................................... 37

6.3 POWER CAPACITOR & BRIDGE RECTIFIER .......................................................... 38

6.4 COMPONENTS & BOM ...................................................................................... 39

6.5 TOTAL COST OF VSC ......................................................................................... 40

6.6 PICTURE SHOWING CAPACITOR & BRIDGE RECTIFIER ....................................... 40

7 CHAPTER– 7: PICTURES OF COMPLETE VSC SETTINGS .................. 42

7.1 CAPACITOR MOUNTING & DC BUS PLATES ........................................................ 42

7.2 VARIOUS LUGS USED IN VSC ............................................................................ 43

7.3 DC BUS CONNECTION WITH RECTIFIER ............................................................. 44

7.4 COMPLETE VSC ................................................................................................ 45

7.5 EXPERIMENTAL RESULTS OF VSI ....................................................................... 47

7.6 PCB SPECIFICATIONS ........................................................................................ 49

7.6.1 Gate driver circuit................................................................................. 49

7.6.2 Gate pulse divider circuit ..................................................................... 49

7.6.3 Power circuit board .............................................................................. 50

6

LIST OF FIGURES

FIG. 1-1: OVERVIEW OF VOLTAGE SOURCE CONVERTER DESIGN ............................................... 10

FIG. 2-1: ACTIVE MILLER CLAMPING CIRCUIT TO PREVENT TURN ON DURING TURN OFF ............ 12

FIG. 2-2: DESAT & ACTIVE MILLER CLAMPING PROTECTION IN GATE DIVIDER CIRCUIT ........... 12

FIG. 2-3: PROTECTION EMPLOYED IN GATE DRIVER CIRCUIT ...................................................... 13

FIG. 2-4: FIGURE OF THE CORELESS TRANSFORMER EMPLOYED IN GATE DRIVER IC .................. 13

FIG. 2-5: GATE DRIVER CIRCUIT PCB ........................................................................................ 17

FIG. 2-6: FRONT VIEW OF VSC SHOWING THREE GATE DRIVER PCB’S ...................................... 17

FIG. 2-7: FRONT VIEW OF SINGLE GATE DRIVER PCB MOUNTED ON MICA BOARD ..................... 17

FIG. 2-8: TOP VIEW OF GATE DRIVER WITH HEAT SINK SEEN BEHIND ......................................... 18

FIG. 2-9: SIDE VIEW OF THE GATE DRIVER PCB SETUP ON THE HEAT SINK ................................. 18

FIG. 2-10: PCB LAYOUT OF COMPONENTS USED IN GATE DRIVER CIRCUIT ................................. 18

FIG. 2-11: TOP COPPER LAYER ROUTING OF GATE DRIVER PCB ................................................. 19

FIG. 2-12: BOTTOM COPPER LAYER ROUTING OF GATE DRIVER PCB .......................................... 19

FIG. 2-13: TOP COPPER LAYER OF GATE DRIVER PCB (WITH COPPER FILL) ................................ 20

FIG. 2-14: BOTTOM COPPER LAYER OF GATE DRIVER PCB (WITH COPPER FILL) ........................ 20

FIG. 3-1: SCHEMATIC CIRCUIT OF GATE-PULSE DIVIDER CIRCUIT............................................... 21

FIG. 3-2: FRC CONNECTOR (MALE) PIN CONFIGURATION........................................................... 23

FIG. 3-3: FAULT TRIP COMMAND TO ALL DRIVER IC ................................................................... 23

FIG. 3-4: RESET CIRCUIT IN GATE PULSE DIVIDER CIRCUIT PCB ................................................ 24

FIG. 3-5: FRONT SIDE OF GATE PULSE DIVIDER CIRCUIT PCB .................................................... 25

FIG. 3-6: BACK SIDE OF GATE PULSE DIVIDER CIRCUIT PCB ..................................................... 26

FIG. 3-7: SIDE VIEW OF GATE DIVIDER PCB SHOWING THE MOUNTING ON ACRYLIC SHEET ........ 26

FIG. 3-8: GATE DIVIDER CIRCUIT PCB AS SEEN IN THE FRONT OF VSC SETUP. .......................... 26

FIG. 3-9: REVERSE SIDE OF THE GATE DIVIDER PCB SHOWING THE ACRYLIC SHEET .................. 26

FIG. 3-10: PCB LAYOUT OF COMPONENTS USED IN GATE PULSE DIVIDER CIRCUIT PCB ............. 27

FIG. 3-11: TOP COPPER AND BOTTOM COPPER LAYER OF GATE DIVIDER PCB ............................ 27

FIG. 3-12: TOP COPPER LAYER OF GATE DIVIDER PCB (WITH COPPER FILL) .............................. 28

FIG. 3-13: BOTTOM COPPER LAYER OF GATE DIVIDER PCB (WITH COPPER FILL) ...................... 28

FIG. 4-1: SCHEMATICS OF POWER CIRCUIT ................................................................................ 29

FIG. 4-2: COMPONENTS IN POWER CIRCUIT PCB ....................................................................... 31

FIG. 4-3: BACK SIDE OF POWER CIRCUIT PCB ........................................................................... 31

FIG. 4-4: POWER CIRCUIT PCB MOUNTED ON HEAT SINK ........................................................... 31

7

FIG. 4-5: POWER CIRCUIT PCB SEEN WITH GATE DRIVER BOARD ............................................... 32

FIG. 4-6: TOP COPPER LAYOUT OF POWER CIRCUIT PCB ........................................................... 32

FIG. 4-7: POWER CIRCUIT PCB ROUTING OF BOTTOM COPPER LAYER ........................................ 32

FIG. 5-1: OUTPUT CHARACTERISTICS OF IGBT SWITCH ............................................................ 34

FIG. 5-2: FORWARD CURRENT & VOLTAGE CHARACTERISTICS OF POWER DIODE ........................ 34

FIG. 5-3: FIGURE SHOWING THE SWITCHING ENERGY LOSS IN AN IGBT SWITCH AND DIODE ..... 34

FIG. 5-4: AVERAGE POWER DISSIPATION OF THREE-PHASE DIODE BRIDGE RECTIFIER................. 34

FIG. 5-5: THERMAL RESISTANCE OF SWITCH & DIODE ............................................................... 35

FIG. 5-6: THERMAL RESISTANCE INCLUDING DIODE BRIDGE RECTIFIER ..................................... 35

FIG. 5-7: OVERALL THERMAL RESISTANCE FROM JUNCTION TO AMBIENT .................................. 36

FIG. 5-8: HEAT SINK WITH HOLE DRILLED FOR IGBT SWITCHES ................................................ 36

FIG. 6-1: FIGURE SHOWING VSC, WITH DIFFERENT CURRENTS IN THE CIRCUIT ......................... 37

FIG. 6-2: THE NORMALIZED RMS EQUIVALENT CENTERED DC BUS CURRENT HARMONICS FOR

SPWM, 1ST CENTERED CARRIER FREQUENCY, 2ND, 3RD

& 4TH MULTIPLE CARRIER FREQUENCY

.......................................................................................................................................... 38

FIG. 6-3: SEMIKRON’S POWER CAPACITOR & DIODE BRIDGE RECTIFIER ................................. 40

FIG. 6-4: CAPACITOR STAND ...................................................................................................... 40

FIG. 6-5: CAPACITOR STAND FIXED ON THE HEAT SINK .............................................................. 41

FIG. 6-6: DIODE RECTIFIER & IGBT SWITCHES MOUNTED ON HEAT SINK .................................. 41

FIG. 7-1: POWER CAPACITORS ALONG WITH THE POWER CIRCUIT BOARD................................... 42

FIG. 7-2: DC BUS PLATES WITH THE SERIES CONNECTED POWER CAPACITORS ........................... 42

FIG. 7-3: LUGS USED IN VSC’S INTERNAL CONNECTION ........................................................... 43

FIG. 7-4: STEEL STRIP USED AS AN EXTENSION OF –VE DC BUS PLATE ....................................... 44

FIG. 7-5: DC BUS PLATES SEEN WITH BRIDGE RECTIFIER ........................................................... 44

FIG. 7-6: DC BUS PLATE SEEN IN TOP VIEW ................................................................................ 44

FIG. 7-7: FRONT VIEW OF VSC .................................................................................................. 45

FIG. 7-8: SIDE VIEW OF VSC ..................................................................................................... 45

FIG. 7-9: TOP VIEW OF VSC ...................................................................................................... 46

FIG. 7-10: ACRYLIC SHEET TO COVER VSC ............................................................................... 46

FIG. 7-11: COMPLETE 2-LEVEL VSC WORKING SETUP .............................................................. 46

FIG. 7-12: EXPERIMENTAL SETUP OF VSI FED INDUCTION MOTOR DRIVE .................................. 47

FIG. 7-13: EXPERIMENTAL RESULTS OF VSI DRIVING AN INDUCTION MOTOR ........................... 47

FIG. 7-14: RESULTS OBTAINED FOR AN INPUT DC VOLTAGE OF 586V ........................................ 48

FIG. 7-15: RESULTS OBTAINED FOR A MAXIMUM LINE CURRENT OF IM ..................................... 48

8

List of tables

TAB. 1-1: VOLTAGE SOURCE CONVERTER SPECIFICATIONS ......................................................... 9

TAB. 2-1: BOM & LIST SHOWING THE COMPONENTS USED IN GATE DRIVER CIRCUIT ............... 16

TAB. 3-1: SIGNALS FROM GATE PULSE DIVIDER CIRCUIT ........................................................... 22

TAB. 3-2: BOM & LIST SHOWING THE COMPONENTS USED IN GATE DRIVER CIRCUIT ................ 25

TAB. 4-1: SIGNALS FROM POWER CIRCUIT PCB ........................................................................ 29

TAB. 4-2: BOM & LIST SHOWING THE COMPONENTS USED IN POWER CIRCUIT ......................... 30

TAB. 6-1: BOM & LIST OF COMPONENTS USED IN RECTIFIER UNIT & OTHER PARTS OF VSC..... 39

TAB. 6-2: TOTAL COST OF VOLTAGE SOURCE CONVERTER SETUP ............................................. 40

TAB. 7-1: LUGS CONNECTING VARIOUS TERMINALS .................................................................. 43

9

1 Chapter – 1: VOLTAGE SOURCE CONVERTER

1.1 INTRODUCTION

Voltage Source Converter (VSC) is an indispensable part of a variety of power

electronic systems. It finds application in motor drives, power factor correcting equipment, grid

integration of renewable energy sources etc. Among other types of inverters, Voltage Source

Inverter (VSI) is more efficient, more robust and gives faster dynamic response. Due to these

reasons, VSC finds a suitable place in most industrial applications.

Two-level VSC’s are mostly used in low voltage, low power applications and in some

medium voltage applications. In order to obtain a better understanding of VSC, a two-level

VSC has been designed and implemented in the following report. The main idea behind

building the inverter is to get a hands-on experience in designing a gate-driver circuit, power

circuit, DC-link bus capacitor, and heat sink which forms the main constituents of a VSC.

1.2 VSC SPECIFICATIONS

S No Ratings Values

1 Inverter kVA 10kVA

2 DC bus voltage 600V

3 Output line voltage 415V rms

4 Output Current 15A rms

5 Switching Frequency 20KHz (max)

6 𝑉𝐶𝐸𝑆 (IGBT rating) 1200V

7 𝐼𝐶 (IGBT rating) 25A @ 100°C

Tab. 1-1: Voltage Source Converter specifications

10

1.3 OVERVIEW OF VSC DESIGN

Fig. 1-1: Overview of Voltage Source Converter design

11

2 Chapter – 2: GATE DRIVERS CIRCUIT

2.1 INTRODUCTION

Gate driver circuit contains a gate driver IC 2ED020I12-F2 (Infineon), with a boot-

strap technique to drive a half bridge of the power circuit. It is an interface circuit between gate

pulse divider circuit and power circuit. This Infineon make IC is chosen as it provides

protection features like IGBT desaturation protection and active miller clamping protection.

On the left side of the driver IC, the signals are exchanged between the gate divider

circuits. This includes the input gate signal to the non-inverting terminal of driver IC, inverting

shutdown logic signal input, ready, /fault,/reset pins corresponding to the high side and low

side of the driver IC. On right is the bootstrap capacitor, diode, protections and exchange of

signals between the IGBT power circuit and driver IC.

2.2 PROTECTIONS IN GATE DRIVER IC

2.2.1 Active miller clamping protection

Active miller clamping protection circuit as shown Fig. 2-1 is employed in gate driver

circuit to prevent parasitic turn-on of IGBT switch during turn off process. During turn off, due

to the sudden rise in CEV , gate voltage rises due to the miller capacitance. When voltage reaches

the IGBT threshold, a dynamic turn on of the power switch occurs. To avoid this, the clamp

pin monitors gate voltage during turn off state. It activates additional discharge path as the gate

voltage sinks 2V below 𝑉𝐸𝐸2𝑋𝑋.

2.2.2 Desaturation protection

Desaturation protection is employed by the DESAT pin. This pin monitors the CEV

voltage to detect desaturation caused by short circuits. If the monitored voltage is above 9V,

and a certain blanking time has expired, the desaturation protection is activated by sending an

active low signal in the /FAULT pin (refer gate pulse divider circuit for further explanation)

and the IGBT is switched off. Blanking time is adjustable by external capacitor. Desaturation

and active miller clamping protections used in the gate driver circuit is shown in Fig. 2-2.

12

Fig. 2-1: Active miller clamping circuit to prevent turn on during turn off

Fig. 2-2: DESAT & Active miller clamping protection in gate divider circuit

2.2.3 /Fault, /Reset & Ready pin functions

Active low /FAULT signal triggers the inverting shutdown input logic, which switches

off the power IGBT switch. For /RESET function, refer gate divider circuit. READY pin gives

a high and low signal depending on the DESAT pin. A high signal is given for normal working

operation (Green LED is connected) and it gives a low signal during fault condition (Red LED

is connected). Fig. 2-3 shows the functionality of above pin functions in the gate driver circuit.

All the explanation is applicable to both high side and low side circuit.

13

Fig. 2-3: Protection employed in gate driver circuit

2.3 FEATURES OF GATE DRIVER IC

The gate drive IC 2ED020I12-F2 has an added feature compared to the existing opto-

coupler and level shifter circuit required for isolation. It is the presence of coreless transformer

isolation provided between the input and output side of the driver IC as shown in Fig. 2-4.

The galvanic isolation is employed in both high side and low side of the driver IC. This

increases the reliability of driver IC compared to the aging of opto-coupler isolation method

and the requirement of level shifter for isolation in output side.

Fig. 2-4: Figure of the coreless transformer employed in gate driver IC

14

2.4 GATE DRIVER CIRCUIT DESIGN

2.4.1 Boot-strap capacitor & diode rating

𝑪𝑩𝑺 = 𝐼𝑄2𝑀𝐴𝑋

∗ 𝑡𝑃 + 𝑄𝐺_𝑀𝐴𝑋

∆𝑉𝐵𝑆=

6 𝑚𝐴 ∗ 1.5𝑚𝑠 + 155 𝑛𝐶

1 𝑉≅ 𝟏𝟎 𝝁𝑭 𝒂𝒕 𝟐𝟓 𝑽

𝑰𝑸𝟐_𝑴𝑨𝑿 = 𝑄𝑢𝑖𝑒𝑠𝑐𝑒𝑛𝑡 𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑂𝑢𝑡𝑝𝑢𝑡 𝐶ℎ𝑖𝑝 𝑖𝑛 𝑔𝑎𝑡𝑒 𝑑𝑟𝑖𝑣𝑒𝑟 𝑑𝑎𝑡𝑎𝑠ℎ𝑒𝑒𝑡

𝒕𝑷 = 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑆𝑤𝑖𝑡𝑐ℎ𝑖𝑛𝑔 𝑝𝑒𝑟𝑖𝑜𝑑

𝑸𝑮_𝑴𝑨𝑿 = 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑡𝑜𝑡𝑎𝑙 𝑔𝑎𝑡𝑒 𝑐ℎ𝑎𝑟𝑔𝑒 𝑣𝑎𝑙𝑢𝑒 𝑜𝑓 𝐼𝐺𝐵𝑇 𝑠𝑤𝑖𝑡𝑐ℎ

∆𝑽𝑩𝑺 = 𝑉𝑜𝑙𝑡𝑎𝑔𝑒 𝑑𝑟𝑜𝑝 𝑎𝑐𝑟𝑜𝑠𝑠 𝑏𝑜𝑜𝑡𝑠𝑡𝑟𝑎𝑝 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑜𝑟

Boot-strap diode rating: Fast recovery diode, 1200V and 1A.

2.4.2 DESAT capacitor for blanking time

𝑪𝑫𝑬𝑺𝑨𝑻 =𝐼𝐷𝐸𝑆𝐴𝑇 ∗ 𝑇𝐷𝐸𝑆𝐴𝑇𝐵𝐿𝐴𝑁𝐾

𝑉𝑅𝐸𝐹_𝐷𝐸𝑆𝐴𝑇=

550𝜇𝐴 ∗ 3𝜇𝑠

9≅ 220pF

𝑻𝑫𝑬𝑺𝑨𝑻𝑩𝑳𝑨𝑵𝑲 = 𝑅𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑏𝑙𝑎𝑛𝑘𝑖𝑛𝑔 𝑡𝑖𝑚𝑒

𝑰𝑫𝑬𝑺𝑨𝑻 = 𝐼𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝑐𝑢𝑟𝑟𝑒𝑛𝑡, 𝑡𝑎𝑘𝑒𝑛 500𝑢𝐴

𝑽𝑹𝑬𝑭_𝑫𝑬𝑺𝑨𝑻 = 𝐷𝐸𝑆𝐴𝑇 𝑟𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑣𝑎𝑙𝑢𝑒, 𝑠𝑒𝑡 𝑖𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝑎𝑠 9𝑉

2.5 COMPONENTS & BOM

s

S

NO

COMPONENT VALUE PACK

AGE

MOUSER

PART NO.

QT

Y

UNIT

PRICE

ORDER

PRICE

1

1

THICK FILM

RESISTOR,

SMD

0Ω,

1/4W, 5%

SMD-

1206

603-

AC1206JR-

070RL

4 2.52 10.08

15

2

THICK FILM

RESISTOR,

SMD

10Ω,

1/4W, 5%

SMD-

1206

603-

RC1206JR-

0710RL

1 1.26 1.26

3

THICK FILM

RESISTOR,

SMD

50Ω,

1/4W, 1%

SMD-

1206

603-

RC1206FR-

0749R9L

2 1.68 3.36

4

THICK FILM

RESISTOR,

SMD

100Ω,

1/4W, 1%

SMD-

1206

603-

RC1206FR-

07100RL

2 1.68 3.36

5

THICK FILM

RESISTOR,

SMD

270Ω,

1/4W, 5%

SMD-

1206

603-

RC1206JR-

07270RL

5 1.26 6.30

6

THICK FILM

RESISTOR,

SMD

820Ω,

1/4W, 1%

SMD-

1206

603-

RC1206FR-

07820RL

1 1.68 1.68

7

THICK FILM

RESISTOR,

SMD

1KΩ,

1/4W, 1%

SMD-

1206

603-

RC1206FR-

071KL

2 1.68 3.36

8

THICK FILM

RESISTOR,

SMD

10KΩ,

1/4W, 5%

SMD-

1206

603-

RC1206FR-

071KL

9 1.26 11.34

9

MULTILAYER

CERAMIC

CAPACITOR,

SMD

220pF,

50V, 10%

SMD-

1206

77-

VJ1206Y221K

XACBC

2 2.17 4.34

10

MULTILAYER

CERAMIC

CAPACITOR,

SMD

100nF,

10V, 10%

SMD-

1206

77-

VJ1206Y104K

XQCBC

8 2.31 18.48

11

MULTILAYER

CERAMIC

CAPACITOR,

SMD

1uF,

10V, 10%

SMD-

1206

77-

VJ1206Y105K

XQTBC

3 4.62 13.86

12

MULTILAYER

CERAMIC

CAPACITOR,

SMD

10uF,

25V, 10%

SMD-

1206

581-

12063C106KA

T2A

4 15.40 61.6

13 MULTILAYER

CERAMIC 4.7uF, 10%

SMD-

1206 81-

GRM31CR71E1 15.89 15.89

16

CAPACITOR,

SMD

475KA88

14

ALUMINIUM

ELECTROLYTI

C CAPACITOR,

SMD

100uF,

16V, 20%

6.3X6.

3X7.7

mm

647-

UUA1C101M

CL1GS

1 20.65 20.65

15

SCHOTTKY

DIODE-BAT

165

750mA,

40V

SOD-

323-2

726-

BAT165E6327

HTSA1

8 20.44 163.52

16

STTH112U –

FAST

RECOVERY

DIODE

1A,

1200V SMB

511-

STTH112U 3 30.10 90.30

17 GREEN LED-

SMD

62.5mW,

20mA

SMD-

1206

604-

APTR3216SG

C

4 6.65 26.60

18 RED LED-SMD 75mW,

20mA

SMD-

1206

604-

APT3216EC 2 7.21 14.42

19 TERMINAL

BLOCK 2P,5mm DIL 651-1888687 4 70.5 282.00

20

FRC

CONNECTOR-

MALE

26 Pin DSC 653-XG2A-

2601 1 205.1 205.1

TOTAL 1 ₹ 957.50

For 3 Gate

Drivers IC’s 3 ₹ 2872.50

Tab. 2-1: BOM & List showing the components used in Gate driver circuit

17

2.6 PICTURES SHOWING GATE DRIVER BOARD IN VSC

Fig. 2-5: Gate driver circuit PCB

Fig. 2-6: Front View of VSC showing three

gate driver PCB’s

Three FRC connector cable to power

divider circuit can be seen in Fig. 2-6

Fig. 2-7: Front View of single gate driver

PCB mounted on mica board

Two Screws are used to place the

mica board on heat sink and it can be

seen in Fig. 2-7

18

Fig. 2-8: Top View of gate driver with heat

sink seen behind

Fig. 2-9: Side View of the gate driver PCB

setup on the heat sink

Length of mica board on which 3 gate driver PCB’s are mounted: 24cmX10cm

2.7 PCB LAYOUT OF GATE DRIVER CIRCUIT

Fig. 2-10: PCB layout of components used in gate driver circuit

19

Fig. 2-11: Top copper layer routing of gate driver PCB

Fig. 2-12: Bottom copper layer routing of gate driver PCB

20

Fig. 2-13: Top copper layer of gate driver PCB (with Copper fill)

Fig. 2-14: Bottom copper layer of gate driver PCB (with Copper fill)

3 Chapter – 3: GATE PULSE DIVIDER CIRCUIT

3.1 INTRODUCTION

Gate pulse divider circuit is the interface between dead band circuit and the half bridge

gate driver circuit. This divider circuit segregates the gating pulse required for three gate driver

circuits along with the short circuit fault protection.

Fig. 3-1: Schematic circuit of Gate-pulse divider circuit

3.2 FUNCTION OF GATE PULSE DIVIDER CIRCUIT

This circuit receives gating signals from dead band circuit and fault signal input (if any)

from the gate driver circuit. The six gating signals are sent to three individual gate driver circuit

through FRC cable and three sets of regulated +5V DC and +15V DC as well. There is a reset

button to reset IGBT switches after fault. The circuit schematics is shown in Fig. 3-1.

22

3.3 SIGNALS IN AND OUT OF GATE PULSE DIVIDER CIRCUIT

This circuit gets input from the DSP for gating signals, +5V, +15V DC from regulated

power supply and fault signal input (if any) from the gate driver PCB. The output from this

circuit are individual FRC connector for each driver PCB, three sets of regulated +5V DC and

+15V DC to each gate driver PCB and a reset command to the gate driver IC to reset all the

switches. Following tables explains the signals in and out of the gate-pulse divider PCB.

In & Out signals of Gate pulse divider Circuit PCB

In

From DSP through dead band – 6 gating signals

(A,/A, B,/B, C,/C)

Regulated +5V and +15V DC Power supply

Fault signal input (active low) from the gate driver IC

( During short circuit – low signal is sent from driver IC )

Out

26 pin FRC (male) connector to each driver PCB

+5V and +15V DC supply to each gate driver PCB

Reset command signal to driver IC to switch off all switches

(Included in the individual FRC pin port)

Tab. 3-1: Signals from Gate pulse divider circuit

In Fig. 3-2, the FRC connector on left side is the six gating pulse required to drive the

switches and on right are the three FRC connectors to three individual gate driver circuits. The

pin description of FRC is shown in Fig. 3-2.On left - A, /A, B, /B, C, /C are the six gating pulse

and on right is the signal given to individual gate driver IC with fault protection and reset

option. INT+X (T-Top switch input, B-Bottom switch input in a leg) is the non-inverting input

of the driver IC and INT-X is the inverting input. Here, gating signals are given to the non-

inverting inputs.

23

Fig. 3-2: FRC connector (male) pin configuration

3.4 PROTECTION CIRCUIT

3.4.1 Fault protection

Active low fault pin (/FLT) in FRC connector to each driver IC is activated whenever

there is a huge current flow due to short circuit problem. Short circuit in the load or arm rises

the collector emitter voltage of the IGBT switches. DESAT pin of the driver IC senses this

voltage and triggers an active low signal (/FLT) if the voltage goes beyond 9V. As shown in

Fig. 3-3, all the three /FLT pin from three driver IC is given to the input of NAND gate and the

output is given to the inverting input of all three driver IC. This compliments the gating logic

of switches and turns off the IGBT.

Fig. 3-3: Fault trip command to all driver IC

24

3.4.2 Reset function

Active low reset button (/RST) in the gate divider circuit resets the driver IC, when it

has previously received a fault input. During normal working it gets ‘+5V’ from the following

reset circuit shown in Fig. 3-4.

Fig. 3-4: Reset circuit in Gate pulse divider circuit PCB


The components used and BOM used in the Gate pulse divider circuit PCB are shown

in the following table.

S

NO COMPONENT VALUE

PACK

AGE

MOUSER

PART NO

QT

Y

UNIT

Price

Order

Price

1 Diode-1N4001 50V,1A DO-41 821-1N4001 1 ₹ 10.43 10.43

2 CARBON FILM

RESISTOR

10KΩ,

0.25W, 5% DO-41

603-CFR-

25JR-5210K 3 ₹ 2.52 7.56

3 CAPACITOR -

CERAMIC 100nF, 10V DIL

140-50V5-

104Z-RC 1 ₹ 19.6 19.6

4 CAPACITOR -

ELECTROLYTIC 1uF, 50V DIL 105CKE100M 1 ₹ 7.10 7.1

5 CAPACITOR -

ELECTROLYTIC 4.7uF,25V DIL

ECA-

1HM47RI 1 ₹ 11.2 11.2

6 CAPACITOR –

100uF,

DIL

ECE-

1 ₹ 17.5 17.5

25

ELECTROLYTIC 16V A1CKA101

7 RESET SWITCH SPST

(LEADS) DIL 1 ₹ 27.5 27.5

8 TERMINAL

BLOCK 2P,5mm DIL 651-1888687 9 ₹ 70.5 634.5

9

FRC

CONNECTOR-

MALE

26 Pin DSC 653-XG2A-

2601 4 ₹ 205.1 820.4

10 NOT GATE 14 Pin DIL 595-

SN74HC14N 1 ₹ 37.8 37.8

11 3 I/P NAND

GATE 14 Pin DIL

595-

SN74LS10N 1 ₹ 53.2 53.2

TOTAL ₹ 1646.7

Tab. 3-2: BOM & List showing the components used in gate driver circuit

3.6 PICTURES SHOWINGOF GATE DIVIDER BOARD IN VSC

Fig. 3-5: Front side of Gate pulse divider circuit PCB

Fig. 3-6: Back side of Gate pulse divider

circuit PCB

Fig. 3-7: Side view of gate divider PCB

showing the mounting on acrylic sheet

Fig. 3-8: Gate divider circuit PCB as seen in

the front of VSC setup.

FRC connector cable is seen coming

out of the gate divider circuit, Also

three individual FRC cables can be

seen connected to three gate driver

circuit inside

Fig. 3-9: Reverse side of the gate divider

PCB showing the acrylic sheet

Gate divider circuit is mounted on the

front part of the acrylic sheet that covers

the whole VSC

3.7 PCB LAYOUT OF GATE DIVIDER CIRCUIT

Fig. 3-10: PCB layout of components used in gate pulse divider circuit PCB

Fig. 3-11: Top copper and bottom copper layer of gate divider PCB

28

Fig. 3-12: Top copper layer of gate divider PCB (With Copper fill)

Fig. 3-13: Bottom copper layer of gate divider PCB (With Copper fill)

29

4 Chapter – 4: POWER CIRCUIT

4.1 INTRODUCTION

Power circuit includes the three leg of the conventional two level voltage Source

Converter. It contains 6 discrete IGBT’s and the output AC three phase power leads(R, Y, B)

as shown in the schematics Fig. 4-1.

Fig. 4-1: Schematics of Power circuit

4.2 SIGNALS IN AND OUT OF POWER CIRCUIT

In & Out signals of Power Circuit PCB

In

From Gate driver PCB – 6 sets of gate signal wires for

each IGBT (blue, yellow pair of wires)

From DC-link Capacitor – 4 connectors for +Vdc (red)

& 1 connector for –Vdc (black)

Out

3-phase output power lead (R, Y, B) taken from the

mid-point of 3 legs (Red, Yellow, Blue connector)

Tab. 4-1: Signals from power circuit PCB

30

4.3 COMPONENTS OF POWER CIRCUIT

IGBT switches are placed at the back side of the PCB shown in Fig. 4-3. In Fig. 4-2,

the AC output leads are the corresponding R, Y, B colored banana connectors.

The lower set of banana connectors are for the DC-link capacitor voltage terminals,

+Vdc and –Vdc connection (4 connectors for +Vdc and 1 connector for -Vdc).

Back to back zener diode is placed to avoid the gate emitter voltage of IGBT’s to go

beyond certain value during short circuit conditions. Here, 20V zener diode is selected.

(For more information, please refer Application note AN4507 in the appendix)


The components used and BOM used in the power circuit PCB are shown in the

following table.

S

NO COMPONENTS VALUE

PACK

AGE PART NO.

QT

Y

UNIT

Price

Order

Price

1 ZENER DIODE,

ZD1-12 20V,10mA DO-41

512-

BZX85C20 12 ₹ 10.50 126

2 IGBT’s 1200V, 25A TO-

247

726-

IKW25T120 6 ₹ 429.10 2574.6

3 CARBON FILM

RESISTOR

1KΩ, 0.25W,

5% MCF DO-41

603-CFR-

25JR-521K 6 ₹ 2.52 15.12

4 POWER

CONNECTOR

BANANA

CONNECTOR DIL 548-31602-0 8 ₹ 161.00 1288

TOTAL ₹ 4003.72

Tab. 4-2: BOM & List showing the components used in power circuit

31

4.5 PICTURES SHOWINGOF POWER CIRCUIT BOARD IN VSC

Fig. 4-2: Components in Power circuit PCB

Fig. 4-3: Back side of Power circuit PCB

Fig. 4-4: Power circuit PCB mounted on heat sink

32

Fig. 4-5: Power circuit PCB seen with gate driver board

4.6 PCB LAYOUT OF POWER CIRCUIT

Fig. 4-6: Top copper layout of Power circuit PCB

Fig. 4-7: Power circuit PCB routing of bottom copper layer

33

5 Chapter– 5: HEAT SINK DESIGN

5.1 INTRODUCTION

In the operation of power semiconductor switches, part of the electric energy is being

transformed into heat energy. In order for any devices to operate within desired temperature

limits, power dissipation performance must be well understood. Power dissipation or losses in

any power semiconductor switches can be classified as conduction loss and switching loss.

5.2 LOSSES IN VSC

5.2.1 Conduction losses

Conduction power loss occurs when the switch is in on position. Eq-4.1&4.2 gives the

conduction loss in an IGBT switch [Refer: AN of IGBT power loss calculation].

2CT CEO Cavg C CrmsP u I r I (4.1)

21 1cos cos1 1

2 8 8 3a a

CT CEO O C O

m mP u I r I

(4.2)

Conduction loss in power diode is given in the equation Eq-3&4.

2Davg D DrmsCD DOP u I r I (4.3)

21 1cos cos1 1

2 8 8 3a a

DCD DO O O

m mP u I r I

(4.4)

Where,

𝒖𝑪𝑬𝑶 = IGBT on-state zero-current CE voltage (0.75 V)

𝒖𝑫𝑶 = on-state zero-current voltage drop across diode (1.25 V)

𝒓𝒄 = CE on state resistance = 𝛥𝑢𝑐𝑒

𝛥𝐼𝑐⁄ (0.045 Ω)

𝒓𝑫 = Diode on state resistance = 𝛥𝑢𝐷

𝛥𝐼𝐷⁄ (0.025 Ω)

𝑰𝒐 = √2 . 𝐼𝑜𝑟𝑚𝑠 (rms value of output current) (10 A)

𝑴𝒂 = Amplitude modulation index (0.98)

34

𝐜𝐨𝐬 𝜱𝟏 = Motor displacement factor (1)

In order to find the CEOu & Cr , the output characteristics of IGBT is to be studied. Fig. 5-1

shows the output characteristics of Infineon IKW25T120 IGBT switch

Fig. 5-1: Output characteristics of IGBT

switch

Fig. 5-2: Forward current & voltage

characteristics of power diode

Similarly, DOu & Dr , can be obtained from the forward current and forward voltage

characteristics of power diode as shown in Fig. 5-2.

Fig. 5-3: Figure showing the switching

energy loss in an IGBT switch and diode

Fig. 5-4: Average power dissipation of

three-phase diode bridge rectifier

5.2.2 Switching losses

Switching loss in both IGBT switch and anti-parallel power diode can be found using the

energy loss graph as shown in Fig. 5-3 . Average power dissipation in the diode bridge rectifier

can be found from the datasheet as shown in Fig. 5-4.

Total power loss, TP = CTP + CDP + rectifierP

130T WP

Thermal dissipation from junction to ambient is given by the Eq-4.5

J AJA

T

T T

P

(4.5)

0.615 /110 30

130

O OO

JAR C WW

(4.6)

Now the thermal resistance of IGBT & diode between junction and case as given in

datasheet would be parallel connected and the effective thermal resistance is 0.3939 /OC W

as shown in Fig. 5-5.

Now, the thermal resistance of paste (1.5°C/W) used in the sink is added to get

1.8939°C/W (1.5 + 0.3939). Six such parallel IGBT’s are pasted onto the sink and thus the

overall thermal resistance is considered to be in parallel and it is1.8939 / 6 0.31565 /OC W .

Thermal resistance of the three-phase diode bridge included with the above resistance is

0.288°C/W as shown in Fig. 5-6.

Fig. 5-5: Thermal resistance of switch &

diode

Fig. 5-6: Thermal resistance including

diode bridge rectifier

Overall junction to ambient thermal resistance is shown in Fig. 5-7 and the sink to ambient

thermal resistance is taken for 10A current case.

36

The volume of the heat sink is found from the following equation,

Volume =𝑉𝑜𝑙𝑢𝑚𝑒 𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 (𝐶𝑚2 °𝐶/𝑊)

𝑇ℎ𝑒𝑟𝑚𝑎𝑙 𝑟𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 (°𝐶/𝑊) =

800

0.4043= 1980 𝐶𝑚3, @ 0.4043 °𝐶/𝑊

Two heat sinks of volume 15X13X7.5cms are mounted on 32X30X2.5cms iron base plate.

Fig. 5-7: Overall thermal resistance from junction to ambient

5.3 PICTURES OF HEAT SINK

Fig. 5-8: Heat sink with hole drilled for IGBT switches

37

6 Chapter– 6: RECTIFIER UNIT & DC BUS CAPACITOR

6.1 INTRODUCTION

Selection of DC-link capacitor is an important part of designing the Voltage Source

Converter (VSC) circuit. In this section, a description of DC-link capacitor design and diode

bridge rectifier have been explained. In order to select a DC-link capacitor, the knowledge of

ripple currents flowing through the capacitor is necessary.

6.2 RIPPLE CURRENTS IN CAPACITOR

In the VSC circuit shown in Fig. 6-1, the ripple currents flowing in the DC-bus capacitor

can be divided into two categories. They are low frequency ripple of 300Hz ( rhI ) and high

frequency ripple of multiple carrier frequencies ( ihI ). These ripple currents in DC-bus depends

on modulation index, load power factor, PWM strategy employed, PWM-VSC carrier

frequency and grid frequency [1]. Low frequency ripple ( rhI ) is found to be 5A from Eq-1.

/10load ph rmsrhVI P (1)

312 10

415103

rhI

= 5A

Where, loadP is rated load power (12KW) & ph rmsV is the per phase grid voltage rms value.

Fig. 6-1: Figure showing VSC, with different currents in the circuit

38

To calculate high frequency ripple current, double FFT 3-D graphics used in [2] is used

for the various operating points (shown in Fig. 6-2). For the selected operating point of

modulation index im =0.78 and pf =0.86 and assuming motor load current of 25A (peak), the

high frequency ripple current ihI obtained is 8.075A. The total ripple current rating of DC-bus

capacitor is found to be 9.5A using the Eq-2.

2 2C rh ihI I I

(2)

2 28.0755CI =9.5A

The DC-bus capacitance value is 1390µF using the Eq-3.

/ (240 )reDC load ripple ph rmsC P V V f (3)

312 10

0.5 415240 600 50

100 3

DCC

= 1390uF

Where, rippleV is 0.5% of DCV (600V) and ref is grid frequency

6.3 POWER CAPACITOR & BRIDGE RECTIFIER

The capacitor used is SEMIKRON’s SKC 3M3-40A-1, 10.1A, which is a 3300µF,

400V, 10.1A ripple current inverter grade capacitor. Two such capacitors are connected in series

to form the required capacitance. Three-phase diode bridge rectifier used is VS-36MT120 rated

for 1200V and 35A.

Fig. 6-2: The normalized rms equivalent centered DC bus current harmonics for SPWM, 1st

centered carrier frequency, 2nd, 3rd & 4th multiple carrier frequency

39


The component used and BOM of power circuit PCB is shown in the following table.

S

NO COMPONENT VALUE

PACK

AGE

MOUSER

PART NO

QT

Y

UNIT

Price

Order

Price

1

ALUMINIUM

ELECTROLYTIC

CAPACITOR –

SCREW

TERMINAL

3300uF,

400V,

11A

EPCOS

/TDK

871-

B43456A9

338M

2 5168.8 10337.6

2

BRIDGE

RECTIFIER –

3PHASE

35A,

1200V D-63

844-

36MT120 1 872.9 872.9

3

BLEEDER

RESISTOR- WIRE

WOUND

25KΩ,

13W

Chassis

mount

588-

GW13J25

K0E

2 374.5 749

4 SNUBBER FILM

CAPACITOR - PP

0.22uF,

1250V

DC

Lug

type

871-

B32656S72

24K564

2 648.9 1297.8

5 POWER

CONNECTORS

BANAN

A

CONNE

CTOR

DIL 548-31602-

0 11 161 1771

8 LUG RING

TYPE

571-

324955 30 15.47 464.1

7

ACRYLIC BOX &

INSULATION

SHEET

1500

9 THERMAL

SHEET 500

10 METAL BASE &

FOR CAPACITOR 1000

TOTAL ₹ 19,492.40

Tab. 6-1: BOM & List of components used in rectifier unit & other parts of VSC

40

6.5 TOTAL COST OF VSC

S No Circuit Cost

1 Gate driver 2,872.50

2 Gate pulse divider 1,646.79

3 Power Circuit 4,003.73

4 Rectifier, Capacitor Units & others 19,492.40

Total ₹ 28,015.41

Tab. 6-2: Total cost of Voltage Source Converter Setup

6.6 PICTURE SHOWING CAPACITOR & BRIDGE RECTIFIER

Fig. 6-3: SEMIKRON’s power capacitor & diode bridge rectifier

Fig. 6-4: Capacitor stand

41

Fig. 6-5: Capacitor stand fixed on the heat sink

Fig. 6-6: Diode rectifier & IGBT switches mounted on heat sink

42

7 Chapter– 7: PICTURES OF COMPLETE VSC SETTINGS

7.1 CAPACITOR MOUNTING & DC BUS PLATES

Fig. 7-1: Power capacitors along with the power circuit board

Fig. 7-2: DC bus plates with the series connected power capacitors

43

7.2 VARIOUS LUGS USED IN VSC

Fig. 7-3: Lugs used in VSC’s internal connection

Lug Purpose – Connecting terminals

a Connecting banana connectors in power circuit & DC bus plates

b Bridge rectifier to DC bus plates & banana connectors

c Capacitor voltages (+ve, mid-point and -ve )

Tab. 7-1: Lugs connecting various terminals

44

7.3 DC BUS CONNECTION WITH RECTIFIER

Fig. 7-4: Steel strip used as an extension of –ve DC bus plate

Fig. 7-5: DC bus plates seen with bridge rectifier

Fig. 7-6: DC bus plate seen in top view

45

7.4 COMPLETE VSC

Fig. 7-7: Front view of VSC

Fig. 7-8: Side view of VSC

46

Fig. 7-9: Top view of VSC

Fig. 7-10: Acrylic sheet to cover VSC

Fig. 7-11: Complete 2-Level VSC working setup

47

7.5 EXPERIMENTAL RESULTS OF VSI

Fig. 7-12: Experimental setup of VSI fed Induction motor drive

Fig. 7-13: Experimental results of VSI driving an Induction Motor

48

Fig. 7-14: Results obtained for an input DC voltage of 586V

Fig. 7-15: Results obtained for a maximum line current of IM

49

7.6 PCB SPECIFICATIONS

7.6.1 Gate driver circuit

Board Title: HALF BRIDGE GATE DRIVER BOARD

Size (length x width): 99.9mm X 77.69mm/ As per Gerber file

Shape: Rectangular

Number of Layers: 2

Component Type: As per Gerber file

Hole diameter: Finished hole size

Minimum Trace Width/Gap: As per Gerber file

Minimum Hole Size:

As per Gerber file

Board Surface Finish ENIG Immersion Gold RoHS

Solder mask: SMOBC. Green on both sides

Electrical Test: Required

Special Info/Instructions: 1. PCB Manufacturing process must be lead-free and

RoHS compliant.

2. PCB Manufacturing must be compliant with IPC-A-

6012 Class 2

Quantity: 3

7.6.2 Gate pulse divider circuit

Board Title: GATE PULSE DIVIDER CIRCUIT BOARD

Size (length x width): 152.4mm X 88.9mm/ As per Gerber file

Shape: Rectangular

Material: 0.063" +/- [10%] high Tg FR4

Number of Layers: 2




Minimum Hole Size: As per Gerber file



50


RoHS compliant.


6012 Class 2

Quantity: 1

7.6.3 Power circuit board

Board Title: INVERTER POWER CIRCUIT BOARD

Size (length x width): 255mm X 75.8mm/ As per Gerber file

Shape: Rectangular

Material: 0.063" +/- [10%] high Tg FR4

Number of Layers: 2




Minimum Hole Size: As per Gerber file

Copper Thickness 2oz. Cu all layers




RoHS compliant.


6012 Class 2

Quantity: 1

51

Reference

[1] A.M. Hava, U. Ayhan, V.V Aban, “A DC bus capacitor design method for various inverter

applications,” IEEE Energy Conversion Congress and Exposition (ECCE), Sep 2012.

[2] U. Ayhan, A.M. Hava, “Analysis and characterization of DC bus ripple current of two-level

inverter using the equivalent centered harmonic appraoch,” IEEE Energy Conversion Congress

and Exposition (ECCE), Sep 2011

[3] Final datasheet of Infineon’s EiceDRIVER 2ED020I12-F2, Dual IGBT Driver IC

[4] Datasheet of Infineon’s discreet IGBT IKW25T120 series

[5] Infineon AN-2006-01: Application Note for driving IGBT’s with unipolar gate voltage

[6] Infineon AN-2014-06 1EDI Compact family: Application Note for Gate driver IC.

[7] Infineon Application Note on “Explanation of discrete IGBTs’ datasheet.

[8] Infineon AN-2013-12: Application Note on “Recommendation for screw tightening torque

for IGBT discrete devices”.

[9] Infineon AN, V1.1, Jan 2009, “IGBT Power losses calculation using the datasheet

parameters” – Refer three phase AC motor drive.

[10] “How to select heat sink” by Seri Lee.

[11] Texas Instruments’ App Report SLVA462-May 2011, “Understanding thermal dissipation

& design of a heat sink”.

[12] Datasheets of all the discrete components used in VSC circuit.

Design and implementation of a 3-phase, 2-Level...

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