ph.d. thesis modeling and simulation of z source inverter design and its control strategies

Modeling and Simulation of Z-Source Inverter Design and Control Strategies

A THESIS SUBMITTED FOR THE AWARD OF DEGREE OF

DOCTOR OF PHILOSOPHY

IN ELECTRONICS AND TELECOMMUNICATION ENGINEERING

UNDER THE FACULTY OF ENGINEERING AND TECHNOLOGY

Supervised by:

Dr. Prashant Shyam Sonare Professor

Submitted by:

Pankaj Hiraman Zope Enrolment No: ET/ST/3

ELECTRONICS AND TELECOMMUNICATION ENGINEERING UNDER THE FACULTY OF ENGINEERING AND TECHNOLOGY

Jodhpur National University, Jodhpur June 2012

Certificate

This is to certify that the thesis entitled “Modeling and Simulation of Z-Source

Inverter Design and Control Strategies” has been undertaken and written

under my supervision and it describes the original research work carried out by

Mr. Pankaj Hiraman Zope, in the faculty of Electronics and Telecommunication

Engineering, Jodhpur National University, Jodhpur for the Degree of Doctor of

Philosophy. To the best of my knowledge and belief, this work has not been

submitted elsewhere for any degree of any other institution in India or abroad.

Dr. Prashant Shyam Sonare

Professor

SSJCET Asangaon Mumbai

Forwarded by:

Dean

Faculty of Engineering and Technology

Jodhpur National University, Jodhpur

Date:

Supervisor’s Certificate

I herby certify that this is based the original research work of

Mr. Pankaj Hiraman Zope Conducted under my supervision. It is certified that the

material from other sources referred to in this PhD Thesis has been duly

acknowledged in the list of references/bibliography and that there is no in

infringement/ violation of the provisions of patent and copyright while incorporating

material derived from other sources.

To the best of my knowledge the research work contained in the thesis has not been

submitted by the PhD scholar working under my supervision or anyone else for the

award of any degree/certificate of any university /institution located anywhere.

Place : Jodhpur Signature of Supervisor

Date of Oral Examination Dr. Prashant Shyam Sonare

PhD Scholar’ S Certificate

I hereby certify that my Ph.D thesis submitted to jodhpur National University for

award of Ph.D Degree is based on my Original Research Work Carried out under

Supervision of Dr. Prashant Shyam Sonare.

I certify that the material form other sources referred to in the PH.D Thesis has been

duly acknowledged in the list of references/ bibliography. I certify that there is no

infringement/ violation of the provisions of paten & copyright while incorporating

material derived from other sources. I further certify that Research work contained

in this thesis has not been submitted by me or anyone else for the award of

degree/certificate of any university institution

I understand that plagiarism is an offence punishable under law and that Ph.D

degree awarded to me may be withdrawn by university in case the above mentioned

offence is traced in my research work even at later date in future.

Place: Jodhpur Signature of Ph.D Scholar

Date : PANKAJ HIRAMAN ZOPE

Dedicated To My Guru

My Beloved Parents, Wife and Children’s Vidhi, Vaibhav

ACKNOWLEDGEMENT

The most important acknowledgment of gratitude I wish to express is to

my mentor and guide Dr. Prashant Shyam Sonare, Principal, SSJCET Asangaon,

Department of Electronics and Telecommunication Engineering, who has put his

valuable experience and wisdom at my disposal. He provided critical advice in my

calculations and suggested many important additions and improvements. It has been

a greatly enriching experience to me to work under his authoritative guidance. It was

only because of his keen interest and continuous supervision that gave my work this

extent form.

I would like to express my deepest sense of gratitude for Honorable

Shri Raosaheb R. D. Shekhawat,(MLA, Amravati) Trustee of my institute (SSBT’s

College of Engineering and Technology Bambhori), who inspired and encouraged me

with his massive words and blessings. He granted me various conveniences without

which it would not have been possible to work. I am very much thankful to our

principal Prof. Dr. K. S. Wani S.S.B.T’s C.O.E.T. Bambhori, Jalgaon who have

motivated me for this research and their constant guidance and support.

For me, it is a proud privilege and a matter of honour to offer my

overwhelming gratitude to Late Prof Dr K. S. Parihar, Retd Professor IIT Powai,

Department of Mathematics, SSBT’s C.O.E.T Bambhori, and Jalgaon for his intellectual

vigor and generous support needed by me. I am thankful to Dr Ajay Somkuwar,

Department of Electronics and Telecommunication Engineering M.A.N.I.T Bhopal for

valuable guidance and suggestion, I am thankful to Dr M.V. Aware, Department of

Electrical Engineering V.N.I.T Nagpur for valuable modification and suggestion, also I

am very much thankful to Dr S. W. Mohod, Department of E&TC Engineering, PRMIT,

Badnera for having given me an opportunity, encouragement and guidance to initiate

this research work form my post graduation.

I am very much thankful to Prof. S. R. Suralkar. H.O.D. E&TC.

S.S.B.T’s C.O.E.T. Bambhori, Jalgaon who have motivated me for this research and

their constant guidance and support. I am also thankful to all staff of our E&TC

DEPARTMENT had been extremely cooperative to me. I express explicitly express my

heartful thanks for their unflinching support.

I am indebted to Prof. K. S. Patil and Prof S. S. Patil who gave valuable

time for support and discussion on related topics.

I am indebted to Prof. S. P. Shekhwat, Director of Academics who

have encouraged me for this research and continuous support.

I would like to thank Professors V. P. Gupta, Dean JNU Jodhpur for

valuable guidance and suggestion.

I would like to thank Professors Avnish Bora, H. O. D Electronics and

Telecommunication Department Jodhpur for valuable guidance and suggestion.

I am indebted to Prof. Rashmi Kalla, Ph.D Co-ordinator who gave her

valuable time for support and discussion on related topics and communication.

I am thankful to authorities and librarians – library of JNU Jodhpur, IIT

Powai, Mumbai, M.A.N.I.T. Bhopal, N.I.T. Nagpur, Nagpur University Nagpur, S.S.B.T’s

C.O.E.T Bambhori for permitting me to borrow journals and books.

Finally, I would like to express my deepest appreciation to my wife Varsha,

children Vaibhav and Vidhi and my parents. Without their constant support and love

none of this would have been possible.

Last but not least, I express profound gratitude to God for the blessing and

grace throughout the life.

Place: Jodhpur

Date:-

PANKAJ HIRAMAN ZOPE

Table of Contents

List of Tables i

List of Figures ii

List of Abbreviations v

Abstract vi

1 Introduction 1

1.1 Research Motivation 1

1.2 Brief Literature Review 2

1.3 Problem Definition 3

1.4 Research Objectives 4

1.5 Thesis Organization 4

2 The Concept of Converter System 6

2.1 Converter 6

2.2 Inverter 6

2.2.1 Introduction of Traditional Voltage Source Inverter 10

2.2.2 Introduction of Traditional Current Source Inverter 12

3 Z-Source Inverter 15

3.1 Introduction 15

3.2 Comparison between VSI, CSI and ZSI 18

3.3 Z-source Inverter design and operation 19

3.4 Design procedure of filter 27

3.5 Conclusion 28

4 Control Strategies for Z-Source Inverter 30

4.1 Introduction 30

4.2 Sinusoidal carrier-based pulse width modulation 31

4.3 Simple boost control method 33

4.4 Result and Discussion 35

4.5 Conclusion 42

5 Modeling and Simulation of Z-Source Inverter 43

5.1 Introduction 43

5.2 Model of traditional inverter 44

5.3 Simulation of traditional inverter 45

5.4 Model of Z-Source inverter 46

5.5 Simulation of Z-Source inverter 48

5.6 Model of control circuit for traditional and Z-Source inverter 49

5.7 Result and Discussion 52

5.8 Conclusion 58

6 Performance and Simulation Analysis of PV System Based On

Z-Source Inverter

59

6.1 Introduction 59

6.2 Modeling of Photovoltaic Arrays 60

6.3 Maximum Power Point Tracking 66

6.4 The Photovoltaic Grid-Connected Power Conditioning System 69

6.5 Operating Principle of ZSI and Controller 70

6.5.1 ZSI Working Strategy 70

6.5.2 Controller Operation 74

6.6 Simulation Results 75

6.7 Conclusion 81

7 Development of Single Phase Z-source Inverter Using ARM-7 for Speed

Control of Induction Motor

83

7.1 Introduction 83

7.2 Block diagram of the system 84

7.3 Model and simulation of the system 85

7.4 Experimental Setup 90

7.4.1 Triggering circuit 91

7.4.2 Gate Driver circuit 93

7.4.3 ARM-7 Microcontroller 94

7.5 Conclusion 97

8 Conclusion and Future Scope 98

8.1 Conclusion 98

8.2 Recommendation of Future Work 99

BIBLIOGRAPHY 102

Appendix

Appendix 1

List of Publications

108

i

List of Table

Table No Name of Table Page No

3.1 Switching states of a single phase ZSI 22

4.1 Component conduction scheme 32

4.2 Switching states of a single phase Z-Source Inverter 34

4.3 Variation of fundamental voltage and current with

modulation index

36


modulation index

37


modulation index

39

5.1 Variation of Modulation index with THD 54

5.2 Comparison of Modulation Index (m) and %THD with

different techniques

55

5.3 Comparison of inverter response with and without filter Vdc

=150v, m = 0.642 and Switching freq 10 KHz

56

6.1 Effect of solar radiation on V-I characteristic of inverter and

active and reactive power

78

ii

List of Figures

Name of Figure Page

No

Figure 2.1: A Basic Power Electronics System 7

Figure 2.2: DC/AC Converter Block. 8

Figure 2.3: (a) Single phase bridge inverter (b) Waveform of the output AC

voltage

9

Figure 2.4: Output AC voltage (a) with zero state (b) with PWM control 10

Figure 2.5: Traditional Voltage Source Inverter 11

Figure 2.6: Traditional Current Source Inverter 12

Figure 3.1: The general configuration of a Z-source converter 15

Figure 3.2: Equivalent circuit of voltage source based Z-Source Converter 16

Figure 3.3: Buck-boost factor of Z source inverter 16

Figure 3.4 : The general configuration of a Z source converter 19

Figure 3.5: Lattice network and converter switching 21

Figure 3.6: Shoot through zero state of a single phase ZSI 23

Figure 3.7: Non shoot through states of a single phase ZSI 23

Figure 4.1: Bipolar sinusoidal carrier based PWM 31

Figure 4.2: Unipolar carrier-based sinusoidal PWM 33

Figure 4.3: Simple boost control 34

Figure 4.4: Switching sequence bipolar sinusoidal carrier-based PWM 36

Figure 4.5: Switching sequence unipolar carrier-based sinusoidal PWM 37

Figure 4.6: Switching sequence simple boost control 38

Figure 4.7: Inductor current 40

Figure 4.8: Voltage across capacitor 40

Figure 4.9: Output current harmonics spectra 41

Figure 4.10: Output voltage harmonics spectra 41

Figure 5.1: IGBT block parameters 44

Figure 5.2: Traditional single phase inverter MATLAB-simulink model 45

Figure 5.3: Traditional inverter fundamental voltage and harmonics spectra 46

Figure 5.4: A Basic block diagram of Z-source inverter System model 47

Figure 5.5: Single phase Z-source inverter MATLAB-simulink model 47

Figure 5.6: Z-source Inverter fundamental voltage and harmonics spectra

without filter

48

Figure 5.7: Z-source Inverter fundamental voltage and harmonics spectra

with filter

49

iii

Figure 5.8: Control circuit as PWM pulse generator circuit 50

Figure 5.9: Switching sequence 51

Figure 5.10: One cycle of modulating signal with carrier wave and switching

sequence

51

Figure 5.11: Inverter output load current and voltage without filter 52

Figure 5.12: Inverter output load current and voltage with LC filter 53

Figure 5.13: Inductor current (IL1) and voltage across capacitor (VC1) 53

Figure 5.14: Inverter fundamental voltage and harmonics spectra without

filter

56

Figure 5.15 Inverter fundamental voltage and harmonics spectra with filter 57

Figure 5.16: Inverter fundamental current and harmonics spectra without

filter

57

Figure 5.17: Inverter fundamental current and harmonics spectra with filter 58

Figure 6.1: The equivalent circuit of a PV cell 60

Figure 6.2: Effect of temperature on PV cell I-V characteristics (ideal

condition)

61

Figure 6.3: PV cell power (ideal condition) 61

Figure 6.4: MATLAB/SIMULINK model of Photovoltaic cell for equation (3) 63

Figure 6.5: PV Cell Characteristics 63

Figure 6.6: PV module 64

Figure 6.7: PV Module Characteristics 64

Figure 6.8: MPP Tracker (variation of irradiance and cell temperature) 65

Figure 6.9 Flowchart of the P&O algorithm 67

Figure 6.10 Flowchart of the IncCond method algorithm 68

Figure 6.11: Schematic diagram of a grid-connected photovoltaic system 69

Figure 6.12: Shoot-through state of simplified ZSI 70

Figure 6.13: Active state of simplified ZSI 71

Figure 6.14: Inductor current (IL1) and voltage across capacitor (VC1) 72

Figure 6.15: The simple boost control for Z-Source inverter 73

Figure 6.16: Control circuit 74

Figure 6.17: PID control signal 75

Figure 6.18: MATLAB-simulink model of single-phase grid connected PV

system based on Z-source inverter

77

Figure 6.19 PV array output voltage 78

Figure 6.20 Inverter fundamental voltage and its harmonics spectra 79

Figure 6.21: Inverter fundamental current and its harmonics spectra 79

Figure 6.22 Inverter output current and voltage varies with solar radiation 80

iv

Figure 6.23 Active and reactive power of inverter varies with solar radiation 81

Figure 7.1: Block diagram of the system 85

Figure 7.2: Matlab/ Simulink model 86

Figure 7.3: Main and auxiliary winding voltage simulation result 86

Figure 7.4: Main and auxiliary winding voltage implementation result 87

Figure 7.5: Main and auxiliary winding current simulation result 87

Figure 7.6: Rotor-speed curve and electromagnetic torque simulation result 88

Figure 7.7: PWM signal simulation result 89

Figure 7.8: PWM signal implementation result 89

Figure 7.9: Experimental setup 90

Figure 7.10: Triggering circuit 92

Figure 7.11: Gate driver circuit 93

Figure 7.12: Single phase Z-source inverter and load 94

Figure 7.13: ARM-7 Control unit 96

v

LIST OF ABBREVIATIONS

A/D: Analog/Digital

AC: Alternating Current

CSI: Current Source Inverter

DC: Direct Current

DSP: Digital Signal Processor

IGBT: Insulated Gate Bipolar Transistor

MOSFET: Metal Oxide Semiconductor Field Effect Transistor

PID: Proportional Integral Derivative

PWM: Pulse Width Modulation

THD: Total Harmonic Distortion

UPS: Uninterruptible Power Supplies

VSI: Voltage Source Inverter

ZSC: Z Source Converter

ZSI: Z Source Inverter

vi

Abstract

In this thesis, the modeling and simulation of a single phase Z-

source inverter and its control methods for implementation dc-to-ac power

conversion is presented.

The design of Z-network and single phase full bridge inverter

modeling and simulation is carried in MATLAB-Simulink environment. A fixed

DC input voltage is given to the inverter and a controlled AC output voltage is

obtained by variable duty cycle or adjusting the on and off periods of the

inverter components. The duty cycle variation can be achieved by using pulse

width modulation (PWM) control methods. Two PWM control strategies are

presented, like Sinusoidal carrier-based PWM and Simple Boost Control.

These methods are described in detail and compared on the basis of

simulation in MATLAB/ Simulink. The ripple of Z-source element, output

voltage, current and their harmonics profile are controlled with variation of

modulation index and switching frequency. Also the effect of shoot through

state on the traditional inverter is eliminated in the Z-source inverter.

Similarly two different applications are presented for verification of the

modeling and simulated system along with two control strategies first is

based on performance and simulation analysis of photo voltaic (PV) system

based on Z-Source inverter. Second application is based on modeling and

simulation of Z-source inverter to control the speed of Induction Motor.

Finally, to validate the simulated system is compared with the

prototype of the single phase Z-source inverter and its control operation

system is developed using ARM-7 microcontroller for speed control of

induction motor.


Ph.D. Thesis (June 2012), Department of Electronics and Telecommunication Engineering. 1 Jodhpur National University, Jodhpur.

1

CHAPTER 1

INTRODUCTION

1.1 RESEARCH MOTIVATION

The power electronics literature focuses the level and characteristics of the

source voltage have been changed using different converter topologies. Each

converter topology has its own restrictions regarding different aspects like number of

components used, stress on semiconductor switches and converter efficiency [2, 3,

32, 33, 58]. Some of these converters have found places in industry for a variety of

applications. Today, efficient power conversion is more important than before because

of the alternative energy sources like fuel cells, solar energy, wind energy and ocean

wave energy that require proper power conditioning to adapt to different loads. Also

hybrid vehicles are very promising new applications of power converters. Moreover,

the area of electrical drives is still demanding for new topologies in order to find more

efficient and cheaper ways of converting the form of energy from electrical to

mechanical or vice versa. Since clean, reliable and high quality energy is one of the

main concerns in today’s world, power electronics will definitely play an important role

in filling this gap.

Power electronics has been widely used in various applications since it was

born. The single phase inverter, which converts dc voltage / current into single phase

ac voltage / current is one of its most important and popular converters. It has been

widely used in uninterruptible power supplies (UPS) [1, 57, 44], used in ac motor

control [15, 16, 21, 28, 29], grid connected PV system [30, 36, 51, 55, 56], etc.

There are two types of traditional inverters, namely voltage source inverter and

current source inverter. However, both inverters have some conceptual barriers, which

will be discussed in detail later. The newly presented Z-source inverter [10-13, 26-29]



has some unique features and it can overcome some of the limitation of the traditional

voltage source and current source inverters. The purpose of this work is to investigate

Modeling and Simulation of a single phase Z-source inverter and its control strategy

for implementation dc-to-ac power conversion.

The research motivation for this thesis also comes from the necessity of

maximum power point tracking (MPPT) for the solar PV panels [4, 6, 7, 9, 22, 24, 35

and 36]. The Z-source inverter and its control system should be capable of tracking

individual maximum power point of the solar panels and ensures the maximum

capture of energy on DC side.

Because of its interdisciplinary nature, power electronics combines

semiconductor devices, digital systems, control theory and power systems. This fact

implies that any innovation in one of these fields affects power electronics and opens

for new research opportunities. Among these fields, control theory is in a very close

relationship with power electronics. This is because power converters are “variable

structure periodic systems” whose state is determined by control signals. In most

applications, converter voltages and currents are to be limited by maximum values

specified by component vendors and to be strictly controlled around a steady state

value defined by the design specifications. This can be achieved by designing

controllers based on true mathematical models. As discussed in the literature many

times, power converters can be modeled based on averaging state variables over a

switching cycle; hence they are suitably conformed for the application of existing

control theories.

1.2 BRIEF LITERATURE REVIEW

The brief review of the research that has been done so far in the literature

about design and control strategies of the Z-source Inverter is presented in this



section. The modeling and simulation of the single phase and three phase Z-source

Inverter [10, 11, 12, 13] is carried out from different perspectives including different

criterion are considered for source, load and controlling and filtering conditions are

given in [25], [38], [40] and [41]. The comparison of traditional inverters and Z-

Source Inverter for fuel cell vehicles is introduced in [26]. Similarly the operating

modes and characteristics of the Z-Source inverter with small inductance are

discussed in [27]. In [39] modeling of Z-source network with inductive loading is

given. In [38] and [39], modeling with an assumption of a constant load current

including Z-source network parasitic resistances is given.

A Comprehensive simulation Analysis of a Three-Phase Z-Source DC-AC

Converter is given in [14]. Z-Source Inverter for power conditioning and utility

interface of renewable energy sources is given in [13] similarly Z-source Inverter

control for traction drive of fuel cell – battery hybrid vehicles is given in [16]. A Pulse

Width Modulation- a survey is introduced in 90’s [18], then the modified carrier –

based PWM modulation technique is given in [37] and the hysteresis band current

control for a single phase Z-source Inverter with symmetrical and asymmetrical Z-

network is given in [17]. An indirect dc-link voltage controller with a modified

modulation method is given in [53]. A PID controller design by direct measurement of

the peak dc-link voltage is given in [54]. Finally, controllers designed for specific

applications, namely fuel cell and voltage sag compensation are given in [40] and

[23].

1.3 PROBLEM DEFINITION

There are two parameters to be changed in order get the desired output AC

voltage in a Z-source inverter. The first one is the modulation index, which also exists

in traditional voltage source inverters. The second one is the boosting factor, which

depends on the shoot-through time. Theoretically, the modulation index can take

values from zero to one, while the boosting factor can take values from one to infinity.

So their multiplication gives all levels of desired voltages at the output. These two



parameters are considered while designing of single phase Z-source inverter and their

control strategies.

1.4 RESEARCH OBJECTIVES

In this thesis, the modeling and simulation of a single phase Z-source

inverter and its control methods for implementation dc-to-ac power conversion is

presented. The design of Z-source inverter modulation and simulation is carried in

MATLAB-Simulink environment along with two different pulse width modulation (PWM)

control methods are discussed: Sinusoidal carrier-based PWM and Simple Boost

Control. These methods are described in detail and compared on the basis of

simulation in MATLAB/ Simulink. The ripple of Z-source element, output voltage,

current and their harmonics profile are varied with modulation index and switching

frequency. Also it focuses the effect of shoot through state on the traditional and Z-

source inverter. Similarly two different applications, first is based on performance and

simulation analysis of photo voltaic (PV) system based on Z-Source inverter and

second is development of single phase Z-source inverter using ARM-7 for speed

control of induction motor are tested for verification of the designed system.

1.5 THESIS ORGANIZATION

A brief overview of the subsequent seven chapters is given in this section.

Chapter 1 provides a general introduction and the purpose of this thesis.

Chapter 2 is based on classification of converter, different power converter

topologies of inverter configurations like voltage source and current source converter.

Chapter 3 presents the Z-network and full wave bridge inverter design and

operation strategy, comparison between VSI, CSI and ZSI. Design procedure of filter.

Chapter 4 discusses the different control strategies, Sinusoidal carrier-

based PWM and Simple Boost Control are adopted for Z-source inverter and its design,

model, simulation and analysis procedure.



Chapter 5 is based on design verification of Z-source inverter system in

chapter 3 with the Modeling and Simulation of Z-Source Inverter carried in MATLAB-

simulink environment.

Chapter 6 is dealing with first application of Z-source inverter. The

performance and simulation analysis of photo voltaic (PV) array is studied by using

MATLAB-simulink modeling and simulation, similarly the active and reactive power of

inverter variation is studied with solar radiation. Maximum power point tracking

algorithms and their necessity in solar PV systems with the proposed topology are

discussed.

Chapter 7 is dealing with second application of Z-source inverter. The

single phase induction motor is interfaced and controlled by the Z-source inverter and

its control methods. The experimental results are compared with the above design

model.

Finally, conclusions and future work are presented in Chapter 8.



1

1

CHAPTER 2

THE CONCEPT OF CONVERTER SYSTEM

2.1 CONVERTER

In electrical engineering, power conversion has a more specific meaning,

namely converting electric power from one form to another. Power conversion systems

often incorporate redundancy and voltage regulation [8].

One way of classifying power conversion systems is according to whether

the input and output are alternating current (AC) or direct current (DC), thus:

DC to DC

o DC to DC converter

o Voltage stabilizer

o Linear regulator

AC to DC

o Rectifier

o Mains power supply unit (PSU)

o Switched-mode power supply

DC to AC

o Inverter

AC to AC

o Transformer/autotransformer

o Voltage converter

o Voltage regulator

o Cycloconverter

o Variable frequency transformer

There are also devices and methods to convert between power systems

designed for single and three-phase operation

2.2 INVERTER

The increased power capabilities, ease of control, and reduced cost of

modern power semiconductor devices have made converters affordable in a large

number of applications and have opened a host of new conversion topologies for

power electronics application. An inverter (power inverter) is an electrical device that

converts DC power or direct current (DC) to AC power or alternating current (AC). The

http://en.wikipedia.org/wiki/AC/AC_Converter

http://en.wikipedia.org/wiki/Autotransformer



converted alternating current (AC) can be at any required voltage and frequency with

the use of appropriate transformers, switching, and control circuits. An inverter (power

inverter) allows you to run electrical equipment computers, emergency equipments,

uninterruptible power supplies (UPS) in medical facilities, life supporting systems, data

centers, telecommunications, industrial processing, online management systems,

adjustable-speed AC drives, automobile applications, and in AC appliances for houses

[19]. When used as UPS, providing uninterruptible, reliable and high quality power for

vital loads becomes critical. They in fact add an extra layer of protection for essential

loads against power outage, as well as over-voltage and over-current conditions.

Figure 2.1: A Basic Power Electronics System

The complete concept, shown in figure 2.1, illustrates a power electronic

system. Such a system consists of an energy source, an electrical load, a power

electronic circuit, and control functions. The power electronic circuit contains switches,

lossless energy storage elements, and magnetic transformers. The controls take

information from the source, load, and designer and then determine how the switches

operate to achieve the desired conversion. The controls are usually built up with

conventional low-power analog and digital electronics. For sinusoidal ac outputs, the

magnitude, frequency, and phase should be controllable. One of the most important

Electrical

Energy

Source

Power

Electronics

Circuits

Electrical

Load

Control

Circuit



issues is the selection of the power electronics circuit topology. To achieve optimal

performance, we need to seriously consider the suitability of the associated power

electronic converter since it is the power electronics technology that enables various

applications.

A typical DC/AC converter system is shown in figure 2.2. Input is from DC

source (voltage or current) and the output is desired to be a sinusoidal voltage or

current with a zero DC component. The load can be a passive R-L-C network, an AC

voltage sink, or an AC current sink. Control parameter can be an angle, a pulse width,

a voltage or a current signal.

Figure 2.2: DC/AC Converter Block.

The simplest form of a DC/AC converter is shown in figure 2.3(a), which is

known as the single phase bridge. Single phase DC/AC conversion can be obtained by

alternately opening and closing the diagonal switch pairs, i.e. S1 and S4 or S2 and S3,

respectively. Figure 2.3(b) shows the output voltage waveform, where either the input

voltage or its negative counterpart is seen at the output depending on the switch

states. Here the parameters of the AC voltage (its RMS value or the amplitude of its

fundamental component) are constant.



Figure 2.3: (a) Single phase bridge inverter (b) Waveform of the output AC

voltage

A common way of varying the AC voltage parameters is to introduce a third

state which is called the zero state. The zero state can be obtained by closing either

the upper leg switches (S1 and S3) or lower leg switches (S2 and S4). Figure 2.4 (a)

shows the output AC voltage of the single phase inverter in figure 2.3 (a) when the

zero state is used to change the AC voltage parameters. Different methods of

harmonic cancellation at the output by introducing this zero state are explained.

Pulse Width Modulation (PWM or wave-shaping) technique is also very

common in DC/AC conversion. Using this high frequency switching technique, it is

possible to eliminate the undesirable low frequency harmonics and high frequency

switching harmonics are easy to filter. The output waveform of the single phase

inverter in figure 2.3 (a) is shown in figure 2.4 (b) when PWM technique is used. Here

two of the four switches (S1 and S2) are switched at high frequency and the other two

(S3 and S4) are switched at low frequency. Low frequency variation of the

fundamental component can be observed after proper filtering.



Figure 2.4: Output AC voltages (a) with zero state (b) with PWM control

Conventional Voltage Source Inverter (VSI) (as shown in figure. 2.5) and

Current Source Inverter (CSI) (shown in figure. 2.6) could be the power electronic

circuits. However, a conventional VSI is a DC-AC buck inverter (AC-DC boost rectifier).

That means the AC output voltage is limited below and cannot exceed the DC bus

voltage or the DC voltage has to be greater than the AC input voltage. On the other

hand, a conventional CSI is a DC-AC boost inverter (AC-DC buck rectifier). The AC

output voltage of CSI has to be greater than the original DC voltage that feeds the

inductor.

2.2.1 Introduction of Traditional Voltage Source Inverter

Figure 2.5 shows the traditional single-phase voltage-source converter

(abbreviated as V-source converter) structure. A dc voltage source supported by a

relatively large capacitor feeds the main converter circuit, a single-phase bridge. The

dc voltage source can be a battery, fuel-cell stack, diode rectifier, and/or capacitor.

Four switches are used in the main circuit; each is traditionally composed of a power

transistor and an antiparallel (or freewheeling) diode to provide bidirectional current

flow and unidirectional voltage blocking capability.



Figure 2.5: Traditional Voltage Source Inverter

It, however, has the following conceptual and theoretical barriers and limitations.

The ac output voltage is limited below and cannot exceed the dc-rail voltage or the

dc-rail voltage has to be greater than the ac input voltage. Therefore, the voltage

source inverter is a buck (step-down) inverter for dc-to-ac power conversion and

the voltage source converter is a boost (step-up) rectifier (or boost converter) for

ac-to-dc power conversion. For applications where over drive is desirable and the

available dc voltage is limited, an additional dc-dc boost converter is needed to

obtain a desired ac output. The additional power converter stage increases system

cost and lowers efficiency.

The upper and lower devices of each phase leg cannot be gated on simultaneously

either by purpose or by EMI noise. Otherwise, a shoot-through would occur and

destroy the devices. The shoot-through problem by electromagnetic interference

(EMI) noise’s misgating-on is a major killer to the converter’s reliability. Dead time

to block both upper and lower devices has to be provided in the voltage source

converter, which causes waveform distortion, etc.

An output LC filter is needed for providing a sinusoidal voltage compared with the

current-source inverter, which causes additional power loss and control

complexity.



2.2.2 Introduction of Traditional Current Source Inverter

Figure 2.6 shows the traditional single-phase current-source converter

(abbreviated as I-source converter) structure. A dc current source feeds the main

converter circuit, a single-phase bridge. The dc current source can be a relatively large

dc inductor fed by a voltage source such as a battery, fuel-cell stack, diode rectifier, or

thyristors converter. Four switches are used in the main circuit; each is traditionally

composed of a semiconductor switching device with reverse block capability such as a

gate-turn-off thyristors (GTO) and Silicon Controlled Rectifier (SCR) or a power

transistor with a series diode to provide unidirectional current flow and bidirectional

voltage blocking.

Figure 2.6: Traditional Current Source Inverter

However, the Current source converter has the following conceptual and theoretical

barriers and limitations.

The ac output voltage has to be greater than the original dc voltage that feeds the

dc inductor or the dc voltage produced is always smaller than the ac input voltage.

Therefore, the current source inverter is a boost inverter for dc-to-ac power

conversion and the current source converter is a buck rectifier (or buck converter)

for ac-to-dc power conversion. For applications where a wide voltage range is



desirable, an additional dc–dc buck (or boost) converter is needed. The additional

power conversion stage increases system cost and lowers efficiency.

At least one of the upper devices and one of the lower devices have to be gated on

and maintained on at any time. Otherwise, an open circuit of the dc inductor would

occur and destroy the devices. The open-circuit problem by EMI noise’s misgating-

off is a major concern of the converter’s reliability. Overlap time for safe current

commutation is needed in the current source converter, which also causes

waveform distortion, etc.

The main switches of the current source converter have to block reverse voltage

that requires a series diode to be used in combination with high-speed and high-

performance transistors such as insulated gate bipolar transistors (IGBTs). This

prevents the direct use of low-cost and high-performance IGBT modules and

intelligent power modules (IPMs).

In addition, both the voltage source converter and the current source converter have

the following common problems.

They are either a boost or a buck converter and cannot be a buck–boost converter.

That is, their obtainable output voltage range is limited to either greater or smaller

than the input voltage.

The VSI is a buck (down) inverter where AC output voltage cannot exceed DC

input voltage. CSI is a boost (up) inverter where AC output voltage is always

greater than the DC voltage feeding the inductor. For applications exceeding

available voltage range an additional boost (or buck) DC/DC converter is needed.

This increases the system cost and decreases the efficiency.



Their main circuits cannot be interchangeable. In other words, neither the voltage

source converter main circuit can be used for the current source converter, or vice

versa.

They are vulnerable to EMI noise in terms of reliability.

For a VSI, the upper and lower switches cannot be on simultaneously which may

cause a short circuit. On the other hand for a CSI one of the upper switches and

one of the lower switches have to be on to provide a path for the continuous input

current. The VSI (CSI) requires dead time (overlap time) to provide safe

commutation which causes waveform distortion.

In a CSI, switch implementation requires diodes in series with the switches. This

prevents the use of low cost switches which come with anti-parallel diodes

implementation, as is usually manufactured.



1

CHAPTER 3

Z-SOURCE INVERTER

3.1 INTRODUCTION

A new type of converter in power conversion, Z-source converter (ZSC)

was introduced in 2002, which has unique features that can overcome the limitations

of VSI and CSI [10-13]. This chapter3 introduces Z-Source Inverter or impedance-

source (or impedance-fed) power converter and its control method for implementing

dc-to-ac, ac-to-dc, ac-to-ac, and dc-to-dc power conversion. The AC voltage from the

Z-source inverter (ZSI) can be controlled, theoretically to any value between zero and

infinity. To differentiate it from any conventional VSI and CSI, the power circuit was

named as Z-source converter. Figure 3.1 shows the general configuration of a Z-

source converter.

Figure 3.1: The general configuration of a Z-source converter

3Contents of this chapter have been published as a paper entitled “Design and

Simulation of Single phase Z-source inverter for utility interface”, International Journal of Electrical Engineering & Technology (IJEET)” (Sep - Oct 2010) ISSN 0976-6553 (online), Volume 1, Number 1, pp 114-130.



Figure 3.2 shows a simplified equivalent circuit for voltage source based

ZSC. In the simplified circuit, the VSI inverter bridge is viewed as an equivalent

current source or drain in parallel with an active switch S2.

Figure 3.2: Equivalent circuit of voltage source based Z-Source Converter

Unlike a conventional VSI, the shoot-through state is not harmful and actually has

been utilized in ZSI. The analysis in [10-13] shows how the shoot-through state over

the non-shoot-through state controls the buck-boost factor of the system. Through the

boost factor in combination with the conventional modulation index M of VSI, the DC-

AC buck-boost factor can be obtained as indicated in figure 3.3.

Figure 3.3: Buck-boost factor of Z source inverter



It is important to note that the process of energy transfer between DC and

AC overlaps the process of energy transfer from DC source to the Z-network. The

overlap process seems very demanding on Switch “S1”. Therefore, for both motoring

and generating operation, S1 is subject to substantial current stresses. In particular,

for a high starting current application, the total current will impose a tremendous

stress on S1 (the starting current plus the current needed to store energy in the Z-

network). The ripple current through C is higher than that through the dc bus

capacitor used in a conventional VSI. In terms of voltage, the boosted dc voltage is

the voltage across the capacitor in ZSI. Additionally, for starting and generating

operation, S1 need to handle bi-directional current and, thus, a diode with an anti-

parallel transistor should be used. The selection of inductors and capacitors for Z-

network is also of great importance. Firstly the reactive components selection should

be guaranteed that no resonance would occur. In addition, the inductance and

capacitance should be large enough to make the inductor current and capacitor

voltage ripple as small as possible. With the shoot-through states evenly distributed

among the pulse width modulation (PWM) cycles, the equivalent switching frequency

seen by the Z-network will be several times of that used in VSI part, implying that

minimization of reactive components is possible [10].



3.2 COMPARISON BETWEEN VSI, CSI AND ZSI

Current Source Inverter Voltage Source Inverter Impedance source

Inverter or Z-Source

Inverter

1. As inductor is used in the

d.c link, the source

impedance is high. It acts as

a const, current source.

As capacitor is used in the

d.c. link, it acts as a low

impedance voltage source.

As capacitor and inductor is

used in the d.c link, it acts as

a const high impedance

voltage source.

2. A CSI is capable of

withstanding short circuit

across any two of its output

terminals. Hence momentary

short circuit on load and mis-

firing of switches are

acceptable.

A VSI is more dangerous

situation as the parallel

capacitor feeds more

powering to the fault.

In ZSI mis-firing of the

switches sometimes are also

acceptable.

3. Used in only buck or boost

operation of inverter.

Used in only a buck or boost


Used in both buck &boost


4. The main circuits cannot

be interchangeable.

The main circuit cannot be

interchangeable here also.

Here the main circuits are

Interchangeable

5. It is affected by the EMI

noise.

It is affected by the EMI

noise

It is less affected by the EMI

noise.

6. It has a considerable

amount of harmonic

distortion

It has a considerable amount

of harmonic distortion

Harmonics Distortion in low

7. Power loss should be high

because of filter

Power loss is high Power loss should be low

8. Lower efficiency because

of high power loss

Efficiency should be low

because of power loss high

Higher efficiency because of

less power loss



3.3 Z-SOURCE INVERTER DESIGN AND OPERATION

The unique feature of the Z-source inverter is that the output ac voltage

can be any value between zero and infinity regardless of the d.c. voltage. That is, the

Z-source inverter is a buck–boost inverter that has a wide range of obtainable voltage.

The traditional V- and I-source inverters cannot provide such feature. The Z-source

inverter is shown in figure 3.4; it employs a unique impedance network (or circuit) to

couple the converter main circuit to the power source, load, or another converter, for

providing unique features that cannot be observed in the traditional V- and I-source

converters where a capacitor and inductor are used, respectively. The Z-source

converter overcomes the above mentioned conceptual and theoretical barriers and

limitations of the traditional voltage source converter and current source converter

and provides a novel power conversion concept.

Figure 3.4 : The general configuration of a Z source converter

The Z-source inverter has three operation modes: normal mode, zero-state

mode, and shoot-through mode. In normal mode and zero-state mode, the ZSI

operates as a traditional Pulse-width modulation (PWM) inverter. The Z-source

inverter advantageously utilizes the shoot-through states to boost the dc bus voltage

by gating on both the upper and lower switches of a phase leg. Therefore, the Z-



source inverter can buck and boost voltage to a desired output voltage which is

greater than the available dc bus voltage. In addition, the reliability of the inverter is

greatly improved because the shoot-through state can no longer destroy the circuit.

Thus it provides a low-cost, reliable, and highly efficient single-stage structure for

buck and boost power conversion [5, 7]. This chapter presents the detailed design

analysis, utilization of the shoot through zero states to boost voltage, the effect of Z-

network and output LC filter on inverter load voltage and current. The designed values

of Z-source inverter is simulated in MATLAB / simulink environment in order to verify

simulation and analysis of single phase Z-source inverter is presented in chapter 5.

A two-port impedance network looks like symmetrical lattice network most

commonly used in filter and attenuator circuit. The lattice network contains L1 and L2

which are series arm inductances, C1 and C2 which are diagonal arm capacitances [1,

5 and 6]. Figure 3.4 shows that the lattice network is connected between the dc

source (voltage or current) and the converter. The dc source can be a battery, fuel

cell, Photovoltaic Array, diode rectifier, thyristor converter, an inductor, a capacitor or

combination of inductor and capacitor. The full bridge converter consists of two legs;

each leg consists of two switches and their anti parallel diodes. The two switches in

each leg are switched in such a way that when one of them is in off state, the other is

in on state. The output current will flow continuously through load and the output

voltage is solely dictated by the status of the switches.



Figure 3.5: Lattice network and converter switching

To understand the design concept of symmetrical lattice network it is

necessary to focus on the operating principle and control of Z-source network. Figures

3.4 and 3.5 show the operating modes of a single phase Z-source inverter. It can

operate in two modes: normal mode and boost mode. The normal operation mode is

like the traditional inverter. The output voltage is dependent on the voltage across the

inverter bridge and on the modulation index. In the boost mode however, the Z-

source inverter boosts the voltage of C1 and C2 (see figures 3.4 and 3.5), thereby

raising the voltage at the inverter bridge. The capacitor voltage of the Z-source

network is a function of shoot- through states. Table 3.1 shows, how the shoot

through state of a single phase Z-source inverter can be controlled. It has five possible

switching states: two active states (vectors) when the dc voltage is connected across

the load, two zero states (vectors) when the load terminals are shorted through either

the lower or the upper two switches and one shoot through state (vector) when the

load terminals are shorted through both the upper and the lower switches of any one

leg or two legs. Z-source inverter utilizes the shoot through zero states to boost

voltage in addition to traditional active and zero states.



Table 3.1: Switching states of a single phase ZSI

Switching states S1 S2 S3 S4 Output Voltage

Active states 1 0 0 1

Finite voltage 0 1 1 0

Zero states 1 0 1 0

Zero 0 1 0 1

Shoot through state

1 1 S3 S4

Zero S1 S2 1 1

1 1 1 1

Figure 3.6 shows a shoot through switching state of the Z-source inverter

where two switches of one leg or two legs are turned on simultaneously. In this state,

the diode D at input side is reverse biased and the capacitors, C1 and C2 charge the

inductors, L1 and L2 and the voltage across the inductors are

VL1=VC1,

VL2=VC2 (3.1)

Assuming a symmetrical impedance network (C1= C2=C and L1=L2=L), we see that

VL1 = VL2 = VL= VL sin (wt + θL)

Vc1 = Vc2 = Vc = Vc sin (wt + θc)

and the output voltage is

Vac = Vdc sin (wt + θ0)

where θL, θc, θ0 are phase angles of Z-source inductor voltage, Z-source capacitor

voltage and output voltage, respectively. Note that VL = VC, IL1 = IL2 =IL and the dc-

link voltage across inverter bridge during shoot through interval (T0) is Vi = 0.



Figure 3.6: Shoot through zero state of a single phase ZSI

Figure 3.7 shows non shoot through states of Z-Source inverter in active

and zero states. Due to symmetrical Z-network, inductors current (IL1, IL2) and

capacitors current (IC1, IC2) are equal. The diode D at the input side conducts and the

voltage across the inductors is

Figure 3.7: non shoot through states of a single phase ZSI

VL=Vdc-VC

or

VC=Vdc-VL (3.2)

Vd = Vdc



The dc-link voltage across Inverter Bridge during non shoot through interval (T1) is

Vi=Vc–VL=2Vc-Vdc (3.3)

where Vdc is the dc source voltage and T = T0 +T1

The average voltage of the inductors over one switching period (T) should be zero in

steady state. Thus from (3.2) and (3.3) we have

0. 1 0.( )0

C C

L

T V T V VV

T

or

1

1 0

C

dc

V T

V T T

(3.4)

Therefore the average dc-link voltage across Inverter Bridge during one switching

cycle (T) is

0 1 1

0

1 0

.0 (2 )C dc

C

T T V V TVi V V

T T T

(3.5)

The peak dc-link voltage across the inverter bridge is expressed by (3.3) which may

be rewritten as

0 0 0

1 0

2 .i C L C

TV V V V V V BV

T T

(3.6)

where

01 0

11

1 2

TB

TT T

T

is the boost factor resulting from the shoot-through zero state. The shoot through

duty cycle is given by (D0) = T0/T.

The peak dc-link voltage is the equivalent dc-link voltage of the inverter. On the other

side, the output peak phase voltage from the inverter can be expressed as

.2

ViVac m

(3.7)

where m is the modulation index.



The voltage gain of the Z-source inverter can be expressed as

. .2

VdcVac m B

(3.8)

The voltage gain of the traditional inverter can be expressed as

.2

VdcVac m

For Z-Source inverter the output voltage is

. .2

VdcVac m B

The output voltage can be stepped up and down by choosing an appropriate buck -

boost factor BB which may be written as

BB= B.M (it varies from 0 to α)

The capacitor voltage can be expressed as

Vc1=Vc2=Vc= (1-To/T).Vdc / (1-2To/T)

=(1-D0).Vdc/1-2D0) (3.9)

The Buck-boost factor BB is determined by the modulation index m and the boost

factor B. The boost factor B can be controlled by duty cycle of the shoot through zero

state over the non-shoot through states of the PWM inverter. The shoot through zero

state does not affect PWM control of the inverter because it equivalently produces the

same zero voltage to the load terminal. The available shoot through period is limited

by the zero state periods determined by the modulation index.

For simulation waveform the dc link voltage Vdc = 200V, and the modulation index

m=0.642 then

D0 = 1-m

where D0 = T0/T, is shoot through duty cycle.

Now, we have, if m = 0.642

D0 = 1 - 0.642 = 0.358

The boost factor is given by



0

1

1 2B

D

= 3.52

During the design of Z-source inverter the estimation of the reactive components such

as impedance network is the most challenging work. The component values should be

evaluated for the minimum input voltage of the converter, when the boost factor and

the current stresses of the components become maximal. Calculation of the average

current of an inductor is carried out by using the relation

L

PI

Vdc

(3.10)

where P is the total power and Vdc is the input voltage.

The maximum current through the inductor occurs when the maximum shoot-through

takes place. This causes maximum ripple current. In our design, 30% (60% peak to

peak) current ripple through the inductors during maximum power operation is

chosen. Thus we have

max .

min .

max min

30

30

. %

. %

L L L

L L L

L L L

I I I

I I I

I I I

The capacitor voltage during that condition is

1 max

2

CVdc VdVc

(3.11)

Calculation of required inductance of Z-source inductors is carried out by the formula

0.

L

T VcL

I

(3.12)

where T0 - is the shoot-through period per switching cycle and we have

T0 = D0 T

The purpose of the capacitor is to absorb the current ripple and maintain a fairly

constant voltage so as to keep the output voltage sinusoidal. During shoot-through,



the capacitor charges the inductors, and the current through the capacitor equals the

current through the inductor. Therefore, the voltage ripple across the capacitor can be

roughly calculated by use of required capacitance of Z-source capacitors. Thus we

have

0avI TVc

C

(3.13)

where Iav is the average current through the inductor, T0 is the shoot-through period

per switching cycle, and C is the capacitance of the capacitor. To limit the capacitor

voltage ripple to 3% at peak power, the required capacitance is

0.

.3%

LT IC

Vc

(3.14)

Another function of the capacitor is to absorb the ripple current.

3.4 DESIGN PROCEDURE OF FILTER

The PWM inverter output voltage is then passed through a LC filter network

to produce a sine wave with less distortion. Based on the previous analysis, the design

procedure of the LC filter can be divided into the following steps:

Based on the nominal dc source voltage Ed and nominal load voltage Vo,

we can calculate the nominal modulation index. Because the voltage drop across the

filter inductor cannot be determined before the parameters of the filters are specified,

this voltage drop can be assumed to be negligible. This assumption is justified because

the voltage drop across the inductor is compensated in part by the filter capacitor. In

order to calculate the nominal modulation index, therefore, the rms value of the

output voltage of the inverter can be assumed equal to the rms value of the load

voltage, that is,

� = √ �� (3.15)



The result is then used to calculate the factor K by using equation

� = √ �� = � − � + �� − �44 (3.16)

2) Based on the nominal load current To, fundamental output frequency-fr, switching

frequency- fs, and the specified value of the total harmonic of the load voltage, the

optimum value of the inductance of the filter can be calculated by using equation

�� = �� {� ��,�� [ + 4� �� ,��]} (3.17)

3) The capacitance of the filter is then calculated by using equation.

�� = � �� ,�� (3.18)

If the dc source voltage varies widely during the operation, the worst value of the dc

voltage that results in the higher value of the output voltage harmonic should be used

in this design.

3.5 CONCLUSION

In this chapter we have studied Z-source inverter design and its operation

strategy. The traditional inverter has dc-link voltage distortion while operating with

either the small source inductor or the light-load consequently output voltage of the

inverter decreases. The Z-source inverter uses a unique LC impedance network for

coupling the converter main circuit to the power source, which provides with a way of

boosting the input voltage, a condition that cannot be achieved in the traditional

inverters. It allows the use of the shoot-through switching state, which eliminates the



need for dead-times that are used in the traditional inverters to avoid the risk of

damaging the inverter circuit.



1

1

1

CHAPTER 4

CONTROL STRATEGIES FOR Z-SOURCE INVERTER

CHAPTER 5

MODELING AND SIMULATION OF Z-SOURCE INVERTER

CHAPTER 6

PERFORMANCE AND SIMULATION ANALYSIS OF PV SYSTEM BASED ON

Z-SOURCE INVERTER

CHAPTER 7

DEVELOPMENT OF SINGLE PHASE Z-SOURCE INVERTER USING ARM-7

FOR SPEED CONTROL OF INDUCTION MOTOR

For Detail study Contact Author

[email protected]



CHAPTER 8

CONCLUSION

8.1 CONCLUSION

This work has following contributions,

The modeling and simulation of Z-network with single phase full bridge

inverter is presented in MATLAB-Simulink environment for the verification of the

design parameters.

Two PWM control strategies are proposed, like Sinusoidal carrier-based

PWM and Simple Boost Control. These methods are described in detail and compared

on the basis of simulation in MATLAB/ Simulink.

The ripple of Z-source element, output voltage, current and their

harmonics profile are varied with modulation index and switching frequency. Also it

focuses the effect of shoot through state on the traditional and Z-source inverter.

Similarly two different applications are successfully presented, first is based

on performance and simulation analysis of photo voltaic (PV) system based on Z-

Source inverter. Second application is based on modeling and simulation of Z-source

inverter to control the speed of Induction Motor.

Finally, the verification of the simulated system is compared with the

experimental prototype of the single phase Z-source inverter and its control operation

is developed using ARM-7 for speed control of induction motor.



8.2 FUTURE SCOPE

In this thesis, the simulation module is built in the Matlab/Simulink

software to verify the proposed single phase Z-source inverter topology performance.

For the future research, the following improvement can be implemented.

With optimization the inductor and the capacitor value of the Z-source

network, the sizing of these electrical components could be minimized to the proper

value, which could reduce the total cost of the proposed topology for the experiment

research.

The modified PWM control strategies may improve the performance of the

inverter up to certain extent. Also by using double switching frequency the component

will result better performance.



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APPENDIX 1

LIST OF PUBLICATIONS

PAPERS PUBLISHED/ COMMUNICATED/ PRESENTED BASED ON THE PH. D. WORK REPORTED

(A) PAPERS PUBLISHED IN JOURNALS

[1] P.H.Zope, “Design and Simulation of Single phase Z-source inverter for utility

interface”, International Journal of Electrical Engineering & Technology (IJEET)”

(Sep - Oct 2010) ISSN 0976-6553 (online), Volume 1, Number 1, pp 114-130.

[2] P.H.Zope, “Performance and Simulation Analysis of Single-Phase Grid

Connected PV System Based on Z-Source Inverter”, 2010 IEEE Conference PEDES-

2010-Power India, Digital Object Identifier: 10.1109/PEDES.2010.5712436, Print

ISBN: 978-1-4244-7782-1.

[3] P.H.Zope, Dr. Prashant Sonare, “Z-source inverter control strategies”,

International Journal of Computational Intelligence and Information Security

(IJCIIS) Australia, August 2011 Vol. 2, No-8, pp 69-78 ISSN: 1837-7823.

[4] P.H.Zope, Dr. Prashant Sonare, “Development of Single Phase Z-source

Inverter Using ARM7 for Speed Control of Induction Motor”, Second International

Conference on Control, Communication and Power Engineering 2011-CCPE Nov-

2011, Proc. published by Springer, V.V. Das and N. Thankachan (Eds.): CIIT 2011,

CCIS 250, pp. 440–443, 2011, © Springer-Verlag Berlin Heidelberg 2011

[5] P.H.Zope, Dr. Prashant Sonare, “Simulation and Implementation of control

strategy for Z-source inverter in the speed control of Induction Motor”

International Journal of Electrical Engineering & Technology (IJEET)” ISSN 0976-

6553 (online), Volume 3, Issue 1, January- June (2012), pp. 21-30

[6] P.H.Zope, Dr. Prashant Sonare, “Speed control of Induction Motor using Z-

source inverter” IEEE Transactions on Power Electronics [In Review]



(B) PAPERS PUBLISHED IN CONFERENCE PROCEEDINGS

[1] P.H.Zope, “Modeling and Simulation of PV cell array system with single-phase

inverter interface for utility management”, International Conference on MEMS and

Optoelectronics Technologies (ICMOT-2010) held at Narsapur AP 23 Jan, 2010

[2] P.H.Zope, “Modeling and Simulation of PV Grid-connected Power Conditioning

System with Z-Source network, August 26-28, 2010, International Conference on

“Electrical Power and Energy Systems (ICEPES 2010). Organized by Department of

Electrical Engineering, Maulana Azad National Institute of Technology, and Bhopal.

[3] P.H. Zope, Z Source Inverter”, National Conference on Advances in

Engineering, Management and General Sciences NCAEMS-2011 28-29 April 2011

organized by Pimpri Chinchwad College of Engineering, Nigadi Pune. 411044

(C) WORKSHOP CONDUCTED AND ATTENDED

[1] MATLAB Applications” held on Saturday 5th and 6th March 2011 at SSBT COET

Bambhori Jalgaon [Conducted and Attended]

[2] “Signal Processing Application with MATLAB” 19th to 23th April 2011 organized

by SSBG COE Bhusaval, dist Jalgaon. [Attended]