Implementation and Design of Switched Boost …Implementation and Design of Switched Boost Inverter...
Transcript of Implementation and Design of Switched Boost …Implementation and Design of Switched Boost Inverter...
Implementation and Design of Switched Boost
Inverter with PWM control Shreya V. Hule1, Pragati N. Korde2,
Electrical Department, Pune University [email protected]
Abstract— Switched Boost Inverter (SBI) is a single stage power converter derived from Inverse Watkins Johnson topology (IWJ).
Switched boost inverter (SBI) is a single-stage power converter suitable for micro-grid because it can provide ac & dc simultaneously
.The output voltage at the AC terminals of SBI for serving ac loads may be higher or lower than the input dc voltage available from
the PV panel. Switched Boost Inverter is advanced version of Z- source inverter which possess better electromagnetic interference
noise immunity. This paper explains mathematical calculations and detailed operation of SBI is explained theoretically and simulated
using MATLAB /Simulink model.
Keywords— Switched Boost Inverter, Inverse Watkins Johnson topology, Z- source inverter, Matlab.
I. INTRODUCTION
Proposed inverter circuit based on the inverse Watkins–Johnson (IWJ) topology that can achieve similar advantages as that of a ZSI. The systematic development of this inverter topology is described starting from the basic IWJ circuit [1]. Pulse Width Modulation (PWM) control strategy for the Switched Boost Inverter is formulated and implemented using a simple analog circuit[2]. The proposed circuit requires two switches and one pair of an LC filter apart from the VSI [3].
The principle operation of SBI can be used as a power conditioning unit in solar PV interfaced micro grid [4]. Switched boost inverter is applicable for renewable energy sources. Figure 1 shows the basic block diagram of switched boost inverter. Renewable energy source such as solar PV is input of SBI. It boosts dc voltage with PWM control signal. SBI convert DC solar input to AC output.
Fig.1 Block diagram of Switched Boost Inverter with PWM control.
The next section reviews mathematical modelling of PWM control switched Boost Inverter and their modes of operation. Section III is followed by its simulation by pulse width modulation control strategy. Section IV is followed by efficiency of PV cell and their fill factor of solar cell. Simulink Model of switched boost inverter with PWM control application for PV generation is explained in section
II SWITCHED BOOST INVERTER
Switched Boost Inverter have property of shoot-through of the inverter legs. It will take care not to cause any damage to the
converter. AC terminal voltage of SBI is higher or lower than given PV cell input.
A Mathematical Modelling
During Ton period (0 < t < D.Ts)
……….(1)
………(2)
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……….(3)
During Toff period (D.Ts < t < Ts)
………….(4)
………….(5)
………….(6)
Using volt second balance, we have
. …………..(7)
From this equation it is clear that varies with duty cycle. When D=0 ratio is unity and it approaches to 0.5 it become very
high. Thus shoot through duty ratio of SBI cannot exceed 0.5
Fig.2. Circuit diagram of Switched Boost Inverter [2]
B Modes of Operation
Fig 3(a) SBI circuit diagram during positive half cycle (b) During negative half cycle the period (1-D)Ts
Mode 1
To explain the steady-state operation of the SBI, assume that the inverter is in a shoot-through zero state for duration D. TS in a
switching cycle TS. The switch S is also turned on during this interval. As shown in the equivalent circuit of Fig 3.3(a) the
inverter bridge is represented by a short circuit during this interval. The diodes DA and DB are reverse biased (as VC > VG),
and the capacitor C charges the inductor L through switch S and the inverter bridge. The inductor current in this interval equals
the capacitor discharging current.
Mode 2
For the remaining duration of the switching cycle (1 −D). TS, the inverter is in non-shoot-through state, and the switch S is
turned off. The inverter bridge is represented by a current source in this interval as shown in the equivalent circuit of Fig. 3.3(b)
now, the voltage source VG and inductor L together supply power to the inverter and the capacitor through diodes DA and DB.
The inductor current in this interval equals the capacitor charging current added to the inverter input current.
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Note that the inductor current is assumed to be sufficient enough for the continuous conduction of diodes DA and DB for the
entire interval (1 − D). TS.
III SINUSOIDAL PWM TECHNIQUES FOR SBI
Fig 4 Schematic representation of PWM signal [2]
Fig 4 shows reference signal , carrier signal and shoot through signal. By comparing refernce signal and carrier signal obtained,
gate signal for S1and S2 and after that the gating signal for S, S2, S4 are obtained with the use of constant shoot through signal.
The sinusoidal refernce signal having frequency is 50Hz and carrier signal frequency is 10KHz. Here shoot through constant
signal is selected as 0.6 and modulation index is ratio of maximum value of reference signal to maximum value of carrier signal
which is selected as 0.6. Where maximum value of carrier signal is assumed to be 1. Figure 4 shows output waveform of
modified PWM control signals. Fundamental output voltage is given as
…………………(8)
The duty ratio D of boost coverter should be chosen such that it does not disturb power interval.
Fig 5: Simuling waveform of sinusoidal signal, triangular signal and shoot through signl
IV SIMULATION AND EXPERIMENTAL RESULT
A Simulation Result
Simulation of Switched Boost Inverter is done using MATLAB software as shown in fig 6. The parameters used in this
simulation are listed in Table 1
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Table 1: Parameters used in simulation
Parameters Values
temperature 250C
Frequency of carrier signal 10kHz
Frequency of reference signal 50Hz
Input capacitor 470uf
Inductor L 5.6mH
Capacitor C 100uF
Filter Inductor Lf 4.6mH
Capacitor filter Cf 10uF
Fig 6. Schematic of PWM control Switched Boost Inverter
Simulations are carried out by using MATLAB R2018A.Simulations are carried out for an input voltage of 65V. The switching frequency is selected as 10 kHz. Different result is obtained from simulation model is shown below.
Fig 7 Input DC Voltage 65 Volt
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Fig 8 Output DC Voltage 188 Volt
Fig 9 Voltage across inverter bridge
Fig 10 AC output Voltage 65 V
B Prototype of switched boost inverter.
Experimental Setup of Switched Boost Inverter as done on dot board. The photograph of the SBI prototype is shown in Fig. 6.1.
The prototype is explained by dividing the entire setup into three functional blocks. The first is the controller circuit, the second
is the gate driver circuit and the third is the main supply.
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Table 2 Prototype specifications.
Parameters/ Components Attributes Component Specifications
Input voltage (Vg) 15V DC S1, S2, S3, S4 MOSFET IRF 540
Fundamental frequency (f0) 50Hz S IGBT 15N120
Switching Frequency (Fs) 10kHz D1, D2 UF 5408, 4Amp, 250V
Shoot through duty ratio (D) 0.4 Gate Driver IR2110 , TLP250
Modulation Index (M) 0.5 Cf 0.1uF ac 400Vac
Inductor(L) 2.2mH Lf 1.2mH 4Amp
Capacitor (C) 220 uF
Output filter Inductor (Lf) 4.6 mH
Output filter Capacitor (Cf) 1uF
Load resistance (R) 100 ohm
Fig 11 Photo of prototype switched boost inverter
1. Controller Circuit-The 18F4520 is a low-power ,high performance CMOS 8 bit microcontroller. It is a very popular ,
low cost , general purpose microcontroller due to their industry standard instruction set. There are two controller circuit
one is used for high frequency i.e controlling main switch S. The other is used for low frequency control i.e for
controlling other switches S1, S2, S3, S4. 230V Ac supply will be step down to 12V-20V by step down transformer.
B0505 IC provide 5V isolate power supply. This 5 V DC will given as input to 18F4520 microcontroller and other
peripheral circuit such as LCD, LED indicator.
2. Gate driver circuit-Gate driver circuit: 5V pulse from the controller IC will be strengthened using the buffer amplifier
i.e., the current will be increased but the voltage remains the same. The output of the buffer amplifier is 5V dc. The
output of the buffer IC will be given as the input to the opt coupler IC. An opto-isolated gate driver is used in order to
provide isolation between the low power controller circuit and the main SBI circuit.
3. Switched Boost Circuit: SBI circuit: 230V AC is stepped down to 12V AC using a step-down transformer. Output of
the transformer is rectified using diode bridge rectifier and rectified DC voltage is fed as input to the SBI circuit. The
SBI output voltage is measured across the load R. Outputs are obtained using the laboratory prototype of the SBI
shown in Fig. The result of the laboratory prototype is used to verify the theoretical analysis simulation results.
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C Hardware Result
Fig 12 AC output and DC output of Switched Boost Inverter and SPWM
TABLE 3 SIMULATED RESULT AND EXPERIMENTAL RESULT
V CONCLUSIONS
This project is based on the development and analysis of Inverters. A prototype of inverter and converter section is tested and
results are experimentally verified. In Future the topology can be extended to decrease in dead time in SBI in with no shoot
through state.
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Parameters Hardware result Simulink result
Input DC voltage 12 Volt 65 Volt
Output DC Voltage 20 Volt 188 Volt
Output AC voltage 10 Volt 65 Volt
Modulation Index 0.5 0.4
Shoot through duty ratio Vary from 0 to 1 0.6
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ISSN NO: 1076-5131
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