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.

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

11
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

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
3
Contents 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
ZeroS1 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 V
V
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 T
Vi 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
T
V V V V V V BV
T T
     
 (3.6)
where
01 0
1
1
1 2
T
B
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
Vi
Vac m
(3.7)
where m is the modulation index.

The voltage gain of the Z-source inverter can be expressed as
. .
2
Vdc
Vac m B
(3.8)
The voltage gain of the traditional inverter can be expressed as
.
2
Vdc
Vac m
For Z-Source inverter the output voltage is
. .
2
Vdc
Vac 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 2
B
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
P
I
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 Vd
Vc


(3.11)
Calculation of required inductance of Z-source inductors is carried out by the formula
0.
L
T Vc
L
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 T
Vc
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 I
C
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
phzope@gmail.com

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]

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