IMPLEMENTATION OF PV BASED HIGH STEP-UP

BOOST CONVERTER AND Z-SOURCE INVERTER SYSTEM

A PROJECT REPORT

Submitted by

AMBETHKUMAR.A 210317105002
MATHAN.P 210317105009
SELVAMUTHU.S 210317105013

In partial fulfillment for the award of the degree

of

BACHELOR OF ENGINEERING
in

ELECTRICAL AND ELECTRONICS ENGINEERING

ARIGNAR ANNA INSTITUTE OF SCIENCE AND TECHNOLOGY

PENNALUR

ANNA UNIVERSITY: CHENNAI 600 025

APRIL - 2021
 ARIGNAR ANNA INSTITUTE OF SCIENCE & TECHNOLOGY
CHENNAI - 602 117
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

BONAFIDE CERTIFICATE
Certified that this project report “IMPLEMENTATION OF PV BASED HIGH
STEP-UP BOOST CONVERTER AND Z-SOURCE INVERTER SYSTEM ” is the
bonafide work of AMBETHKUMAR.A(210317105002), MATHAN.P(210317105009),
SELVAMUTHU.S (210317105013) who carried out the project work under my
supervision. Certified further, that to the best of my knowledge the work reported here in
does not form part of any other project report or dissertation on the basis of which a degree
or award was conferred on an earlier occasion on this or any other candidate.

SIGNATURE SIGNATURE

Mr.K.J.JAGADEESAN M.E., Mr.K.SATHIYAMURTHI M.E.,

ASSISTANT PROFESSOR, HEAD OF THE DEPARTMENT,

PROJECT SUPERVISOR, Electrical and Electronics Engineering,

Electrical and Electronics Engineering, Arignar Anna Institute of Science &

Arignar Anna Institute of Science &Technology, Technology,

Chennai-602117 Chennai-602117

Submitted to Project and Viva-Voce Examination held on ------------------------

INTERNAL EXAMINER EXTERNAL EXAMINER

 ACKNOWLEDGEMENT

I would like to express my deep sense of heartiest thanks to my beloved

chairman Dr.VIRGAI.G.JAYARAMAN B.A., and vice-chairman
Mr.J.KUMARAN M.E., M.B.A.,(UK), Chairperson Mrs.J.NIRMALA MBA.,
MCA., for giving an opportunity to do and complete this project.

Principal Dr.M.MURALI KRISHNAN Ph.D., and our Vice-Principal,

Dr.M.SUBISTALIN Ph.D., for creating a beautiful atmosphere, which inspired me
to take over this project.

I take opportunity to convey my heartiest thanks to my

HOD Mr.K.SATHIYAMURTHI M.E., and my project coordinator
Mr.K.J.JAGADEESAN M.E., Assistant professor for his much valuable support,
unfledged attention and direction, which kept this project on track.

I extremely thanks to my project supervisor Mr.K.J.JAGADEESAN M.E.,

Assistant professor of Electrical and Electronics Engineering for this much needed
guidance and specially for entrusting us with my project.

I would like to express my heartiest thanks to lab assistants and to all other
faculties, non-teaching members of our department for their support and pears for
having stood by me and help me to complete this project.

Finally I thank for my class friends for their timely help in shaping our project.

AMBETHKUMAR.A,

MATHAN.P,

SELVAMUTHU.S.
 ABSTRACT

In this project proposed transformer less modular interleaved boost converter is used

to achieve high step-up ratio and high efficiency for AC-Micro Grid applications. The output

of Photo Voltaic panel (PV) is given to the Interleaved Boost Converter (IBC).Using the

Z-source inverter convert high step up AC voltage from high step up dc voltage to the load/

micro grid applications. By using the soft switching (ZVS) to reduce the voltage stress,

switching loss and conduction loss. The ZSI has reliable and highly efficient for boost

conversions and reduce the harmonics. It is seen that, for higher power applications, more

converter modules can be paralleled to increase the power rating and the dynamic

performance. Then, steady-state analysis is made to show the merits of the proposed

converter module. The performance of the proposed system is validated with simulations

carried out using MATLAB software. As an illustration, Open-loop control of interleaved

boost converter and z source inverter system consisting of 24 V DC input and 230 V AC

output is implemented for demonstration.

 TABLE OF CONTENTS

CHAPTER TITLE PAGE

NO
ABSTRACT III
LIST OF FIGURES V
LIST OF ABBERVATION VII
1 INTRODUCTIONS
1.1 INTRODUCTIONS 1
1.2 LITERATURE SURVEY 2
1.3 OBJECTIVE 4
1.4 ORGANISATION OF REPORT 4
2 BLOCK DIAGRAM
2.1 BLOCK DIAGRAM 5
2.2 STAND-ALONE PV SYSTEM 5
2.3 COMPONENTS OF STAND-ALONE PV SYSTEM 5
2.4 PV GENERATOR 6
2.4.1 SOLAR CELL MODEL 6
2.4.2 SOLAR MODULE MODEL 10
2.4.3 ARRAY MODEL 11
2.5 BATTERY 11
2.6 CONTROLLER 11
2.7 INVERTER 12
2.8 ADVANTAGES OF STAND-ALONE PV SYSTEM 12
2.9 APPLICATIONS OF STAND-ALONE PV SYSTEM 12

3 SYSTEM ANALYSIS

3.1 OPERATION PRINCIPLE 13

3.2 MODES OF OPERATION 14
3.3 STEADY-STATE ANALYSIS 15
 3.4 VOLTAGE STRESS OF THE POWER DEVICES 20
3.5 MODELING OF THE PROPOSED MODULAR CONVERTER 20
3.5.1. DC MODEL 21
3.5.2. AC MODEL 21
3.6 PARALLEL OPERATION CONTROL 22

4 Z- SOURCE INVERTER
4.1 INTRODUCTION 23
4.2 IMPEDANCE NETWORK 23
4.3 EQUIVALENT CIRCUIT AND PRINCIPLE OF OPERATION 24
4.4 MODELLING OF Z-SOURCE INVERTER 26
4.5 TOTAL HARMONIC DISTORTION 27
4.6 ADVANTAGES OF Z-SOURCE INVERTER 27

5 SIMULATION RESULTS
5.1 GENERAL 28
5.2 THE ROLE OF SIMULATION IN DESIGN 29
5.3 INTRODUCTION TO MATLAB 30
5.4 SIMULATION RESULT 30

6 CONCLUSION
6.1 CONCLUSION 37
6.2 FUTURE SCOPE 37
REFERENCES 38
 LIST OF FIGURES

FIGURE TITLE OF FIGURE PAGE

NO
2.1 BLOCK DIAGRAM OF PROPOSED SYSTEM 05
2.2 BLOCK DIAGRAM FOR THE STAND-ALONE
PV SYSTEM 06
2.3 PV CELL EQUIVALENT CIRCUIT 07
2.4 A TYPICAL CURRENT- VOLTAGE V-I CURVE
FOR A SOLAR CELL 08
2.5(a) INFLUENCE OF THE AMBIENT IRRADIATION
AND OF THE CELL TEMPERATURE 09
2.5(b) INFLUENCE OF THE AMBIENT IRRADIATION
ON THE CELL CHARACTERISTICS 09
2.6(a) SERIES 09
2.6(b) PARALLEL CONNECTION OF IDENTICAL CELLS 09
2.7 THE PV MODULE CONSISTS OF NPM PARALLEL
BRANCHES, EACH OF NSM SOLAR CELLS IN
SERIES 10
2.8 SOLAR CELL ARRAY CONSISTS OF MP
PARALLEL BRANCHES, EACH WITH MS
MODULES IN SERIES 11
3.1 PROPOSED MODULAR HIGH STEP-UP BOOST
CONVERTER TOPOLOGY 13
3.2 KEY WAVEFORMS OF THE PROPOSED
CONVERTER 16
3.3(a) CHARACTERISTIC ANALYSES OF THE
PROPOSED CONVERTER VOLTAGE
CONVERSION RATIO COMPARISONS 19
3.3(b) NORMALIZED SWITCH VOLTAGE STRESS
UNDER DIFFERENT VOLTAGE CONVERSION
RATIO 19
3.3(c) NORMALIZED DIODE VOLTAGE STRESS
UNDER DIFFERENT VOLTAGE CONVERSION
RATIO 19
4.1 SINGLE PHASE FULL BRIDGE Z SOURCE
INVERTER 23
4.2 SYSTEM CONFIGURATION 24
4.3 EQUIVALENT CIRCUIT OF THE ZSI IN ONE OF
THE SIX ACTIVE STATES 25
4.4 EQUIVALENT CIRCUIT OF THE ZSI IN ONE OF
THE TWO TRADITIONAL ZERO STATES 25
4.5 EQUIVALENT CIRCUIT OF THE ZSI IN
THE NON SHOOT-THROUGH STATES 26
4.6 EQUIVALENT CIRCUIT OF THE ZSI IN
THE SHOOT-THROUGH STATES 26
5.1 SIMULATION CIRCUIT OF PV PANEL 30
5.2 SIMULATION CIRCUIT OF HIGH STEP – UP
INTERLEAVED BOOST CONVERTER (IBC) 30
5.3 INPUT VOLTAGE OF HIGH STEP – UP
INTERLEAVED BOOST CONVERTER 31
5.4 OUTPUT VOLTAGE OF HIGH STEP – UP
INTERLEAVED BOOST CONVERTER 31
5.5 OUTPUT CURRENT OF HIGH STEP – UP
INTERLEAVED BOOST CONVERTER 31
5.6 OUTPUT POWER OF HIGH STEP – UP
INTERLEAVED BOOST CONVERTER 32
5.7 SIMULATION CIRCUIT OF HIGH STEP – UP
INTERLEAVED BOOST CONVERTER WITH
MOTOR LOAD 32
5.8 OUTPUT SPEED AND TORQUE OF MOTOR 32
5.9 SIMULATION CIRCUIT OF PROPOSED SYSTEM
USING R LOAD 33
5.10 INPUT VOLTAGE OF PROPOSED SYSTEM
USING R LOAD 33
5.11 OUTPUT VOLTAGE OF PROPOSED
SYSTEM USING R LOAD 33
5.12 OUTPUT CURRENT OF PROPOSED SYSTEM 34
USING R LOAD
5.13 OUTPUT POWER OF PROPOSED SYSTEM
USING R LOAD 34
5.14 SHOWS THE FFT ANALYSIS OF ZSI AND
THD IS 5.12% 34
5.15 SIMULATION CIRCUIT OF PARALLEL
CONNECTION IBC WITH Z SOURCE INVERTER 35
5.16 OUTPUT POWER OF PARALLEL CONNECTION
IBC WITH Z SOURCE INVERTER USING R LOAD 35
5.17 SIMULATION CIRCUIT OF PROPOSED
SYSTEM CONNECTED TO GRID 35
5.18 OUTPUT VOLTAGE OF PROPOSED SYSTEM
CONNECTED TO GRID 36
5.19 EFFICIENCY OF VARIOUS INPUT VOLTAGE 36
 LIST OF ABBREVATION

PV - Photo voltaic
IBC - Interleaved Boost Converter
ZVS - Zero Volt Source
ZSI - Zero Selective Interlocking
MPP - Maximum Power Point
THD - Total Harmonic Distraction
 1

CHAPTER 1
INTRODUCTION
INTRODUCTION
The public concern about global warming and climate change, much effort
has been focused, limited fossil energy and increased air pollution have spurred
researchers to develop clean energy sources in recent years. The photovoltaic (PV)
power generation system is a clean, quiet and an efficient method for generating
electricity. Photovoltaic cells convert sunlight directly to electricity. They are
basically made up of a PN junction. The photocurrent generation principle of PV
cells. In fact, when sunlight hits the cell, the photons are absorbed by the
semiconductor atoms, freeing electrons from the negative layer. This free electron
finds its path through an external circuit toward the positive layer resulting in an
electric current from the positive layer to the negative one. The PV panel could be
used in battery charging, water pumping, PV vehicles, satellite power systems, grid-
connected power systems, standalone power systems, and numerous practical
applications. The low conversion efficiency of PV panel, on way to reduce the cost
of the overall system is by using high efficiency power processors. A DC to DC
converter is used as energy processing system in panel processor. When a DC/DC
converter is used in a PV panel power system, it is operated at the maximum power
point (MPP) of the PV panel. The maximum possible power is extracted for
increasing the utilization rate of the PV panel.
An interleaved boost converter (IBC) could be extended magnetically
coupling a boost type auxiliary step-up circuit that charges a voltage-doubler in the
output in order to achieve the required voltage gain. A modular integrated boost
converter which provides an additional step-up gain with the help of a coupled
inductor auxiliary step-up circuit was also proposed. An another technique is by
using the z-source inverter converts high step up AC voltage from high step up DC
voltage to the load/ micro grid applications. Advantages of Z-source inverter (ZSI)
has reliable and highly efficient for boost conversions and reduce the
harmonics.The advantage of a AC micro grid are that loads/sources/ and energy
 2

storage can be connected through a simpler and more efficient power electronic
interfaces. AC micro grids have been used in sensitive load, industrial, and
residential house.

LITERATURE SURVEY

1. Ki-Bum Park, Myung-Joong et al (2010) proposed non isolated high step-up

applications, the SIB converter, which combines a boost converter and an isolated
sepic converter with one switch, is introduced in this paper. The SIB converter can
achieve a high-voltage gain with the additional step-up ability of the isolated sepic
converter and distributed voltage stress, while maintaining the advantages of the
boost converter, such as a continuous input current and a clamped voltage stress on
switch. Moreover, the reverse recovery problem is well suppressed, since the
transformer leakage inductance alleviates a di/dt ratio of the turn-off diode current
without additional snubber and the voltage stress on the secondary diode is limited
by the clamp diodes. Therefore, the SIB converter is promising for non isolated
high step-up applications with simple structure and high efficiency. It is noted that
other converters, which have a boost inductor and a switch as an input stage, can
also be integrated with the boost converter similar to the SIB converter.

2. D. Mahinda Vilathgamuwa, Chandana Jayampathi Gajanayake (2009) In this

paper, modulation and controlling of the paralleled Z source inverter system for DG
application is proposed. The DG system is designed to operate in both grid-
connected and islanding modes. Toward this end, a carrier-based modulation
method is proposed and the modulation method is designed based on simple shoot-
through with interleaved carrier signals. The dc-side controller is designed to supply
a constant input voltage to the inverters while rejecting disturbances from the
supply side by varying the shoot-through time appropriately. The ac-side controllers
are designed to deliver constant active and reactive power in the grid-connected
mode. The current references are generated using an outer power loop.
 3

3. Ching-Tsai Pan, Ching-Ming Lai, et al (2009) proposed A two-phase

interleaved boost converter with low switch voltage stress is proposed for single-
phase power factor correction. Due to the forward-type converter integrated and
additional capacitors added to the two phases, the proposed converter can achieve
much higher step-up voltage gain and lower voltage stress of its switches under
low-line input voltage. Furthermore, the current can be shared uniformly by each
phase without any additional current-sharing control.

4. Dong Wang, Xiangning He, et al (2008) A new type of interleaved boost

converter with coupled inductors and switched capacitors is proposed in this paper.
Due to the coupled inductors and switched capacitors added to the output stage, this
type of converter has higher step-up voltage gain and lower voltage stress of its
switches in contrast with the conventional interleaved boost converter. Therefore,
the low-conduction resistance and low-voltage-rated switches can be applied.
Moreover, the load current can automatically be equally shared by each phase
without any additional current sharing module. The leakage energy of the coupled
inductor is recycled by the active-clamp circuit, which increases the efficiency.

5. Ching-Tsai Pan,Yi-Hung Liao (2007) proposed, to the best of the authors’

knowledge, precise circulating-current definition of paralleled multiphase
converters is proposed for the first time. Based on the definition, the corresponding
circulating-current model is derived systematically. The existence of the intrinsic
circulating current explains why the resulting current waveform distortion always
exists more or less, as can be observed from the experimental results of existing
papers. From this paper, one can see that even if all the converters are synchronized,
there always exist closed loops, and the Resulting circulating currents will be
distributed according to the variation of the line impedances. In addition, due to the
short time periods of the existing closed loops, the resulting high frequency
components cannot be controlled by the controller because of the finite bandwidth
as well as the limited switching speed of active switches.
 4

6. T. J. Liang and K. C. Tseng (2005) proposed, the operating principles,

theoretical analysis, and design methodology of a high-efficiency step-up converter
are presented. The integrated boost-fly back converter (IBFC) uses coupled-
inductor techniques to achieve high step-up voltage with low duty ratio The voltage
gain and efficiency at steady state are derived using the principles of inductor volt-
second balance, capacitor charge balance and the small-ripple approximation for
continuous-conduction mode.
OBJECTIVE
The objective of the project to develop a modular high-efficiency high step-
up boost converter with a forward energy-delivering circuit integrated voltage-
doubler as an interface for ac-micro grid system applications. In the proposed
topology, the inherent energy self-resetting capability of coupled inductor can be
achieved without any resetting winding. Moreover, advantages of the proposed
converter module such as low switcher voltage stress, lower duty ratio, and higher
voltage transfer ratio features are obtained. Steady-state analyses are also made to
show the merits of the proposed converter topology. For further understanding the
dynamic characteristic, small-signal models of the proposed converter are derived
by using state-space averaging technique. For higher power applications, modules
of the high step-up converters are paralleled to further reduce the input and output
ripples. Analysis and control of the overall system are also made.

ORGANISATION OF REPORT
In chapter 1, brief introduction of the project that it deals with the designing
of a Implementation of PV based high step-up boost converter and Z-source inverter
system. This chapter comprises of the literature survey, objective and the
organization of report.
In chapter 2, block diagram of proposed system, detailed study of standalone
PV system and its components, its advantages, applications are studied.
In chapter 3, deals the circuit diagram with system configuration and
operating principle of interleaved boost converter (IBC) to step up the high voltage
gain.
 5

In chapter 4, deals introduction of Z-source inverter and its operating

principle, conversion of DC TO AC, advantages, THD.
In chapter 5, simulation PV based high step-up boost converter and Z-source
inverter system and its simulation results and output waveforms are studied.
In chapter 6, conclusion and future scope of the proposed system.
 6

CHAPTER 2
BLOCK DIAGRAM
BLOCK DIAGRAM

Fig 2.1 Block diagram of proposed system

STAND-ALONE PV SYSTEM
Stand-alone PV systems are also called autonomous PV systems which are
independent Photovoltaic systems. They are normally used in remote or isolated
places where the electric supply from the power-grid is unavailable or not available
at a reasonable cost. Examples for such an application are mountain huts or remote
cabins, isolated irrigation pumps, emergency telephones, isolated navigational buoy,
traffic signs, boats, camper vans, etc. They are suitable for users with limited power
need.

COMPONENTS OF STAND-ALONE PV SYSTEM

The main purpose of this section is to describe the models for the elements
of a stand- alone PV system: PV generator, battery, controller, inverter and load.
The modelling of the PV system is based on modular blocks, as illustrated in Fig.
2.2. The modular structure facilitates the modelling of the other system structures
and replacing of elements, for instance a DC load instead of an AC load.
 7

Fig.2.2 Block diagram for the stand-alone PV system

PV GENERATOR
A photovoltaic PV generator is the whole assembly of solar cells,
connections, protective parts, supports etc. In the present modeling, the focus is
only on cell/module/array.
Solar cells are made of semiconductor materials (usually silicon), which are
specially treated to form an electric field, positive on one side (backside) and
negative on the other (towards the sun). When solar energy (photons) hits the solar
cell, electrons are knocked loose from the atoms in the semiconductor material,
creating electron-hole pairs (Lorenzo, 1994). If electrical conductors are then
attached to the positive and negative sides, forming an electrical circuit, the
electrons are captured in the form of electric current Iph (photocurrent).

SOLAR CELL MODEL

During darkness, the solar cell is not an active device; it works as a diode,
i.e. a p-n junction. It produces neither a current nor a voltage. However, if it is
connected to an external supply (large voltage) it generates a current ID, called
 8

diode current or dark current. A solar cell is usually represented by an electrical

equivalent one-diode model (Lorenzo, 1994), as shown in Fig.2. 3.

Fig. 2.3 PV cell equivalent circuit.

The model contains a current source Iph, one diode and a series resistance RS,
which represents the resistance inside each cell and in the connection between the
cells. The net current is the difference between the photocurrent Iph and the normal
diode current ID:

where is idealizing factor, is Boltzmann’s gas constant, TmIkc the absolute

temperature of the cell, electronic charge and V is the voltage imposed across the
cell. is the dark saturation current and it is strongly depending on temperature
(Lorenzo, 1994) e0 Fig. 2.4 shows the V-I characteristic of the solar cell for a
certain ambient irradiation Ga and a certain fixed cell temperature Tc.

Fig.2.4 A typical current- voltage V-I curve for a solar cell

 9

In the representation of V-I characteristic, a sign convention is used, which

takes as positive the current generated by the cell when the sun is shining and a
positive voltage is applied on the cell’s terminals.If the cell’s terminals are
connected to a variable resistance R, the operating point is determined by the
intersection of the V-I characteristic of the solar cell with the load V-I characteristic
- see Fig 2.4. For a resistive load, the load characteristic is a straight line with a
slope I/V=1/R. It should be pointed out that the power delivered to the load depends
on the value of the resistance only. However, if the load R is small, the cell operates
in the region MN of the curve, where the cell behaves as a constant current source,
almost equal to the short circuit current. On the other hand, if the load R is large, the
cell operates on the region PS of the curve, where the cell behaves more as a
constant voltage-source, almost equal to the open-circuit voltage.
(a) Short circuit current: ISC= IPh It is the greatest value of the current generated by
a cell. It is produced under short circuit conditions: V=0.
(b) Open circuit voltage: corresponds to the voltage drop across the diode (p-n
junction), when it is traversed by the photocurrent Iph (namely ID=Iph), namely when
the generated current is I=0. It reflects the voltage of the cell in the night and it can
be mathematically expressed as:

(c) Maximum power point is the operating point A (Vmax, Imax) in Fig.2.4, at which
the power dissipated in the resistive load is maximum:

(d) Maximum efficiency is the ratio between the maximum power and the incident
light power:

Where Ga is the ambient irradiation and A is the cell area.

 10

(e) Fill factor is the ratio of the maximum power that can be delivered to the load
and the product of Isc and Voc:

The fill factor is a measure of the real V-I characteristic. Its value is higher
than 0.7 for good cells. The fill factor diminishes as the cell temperature is
increased. In Fig. 2.4, an V-I characteristic of a solar cell for only a certain ambient
irradiation Ga and only a certain cell temperature Tc is illustrated. The influence of
the ambient irradiation Ga and the cell temperature Tc on the cell characteristics is
presented in Fig 2.5.

Fig 2.5 Influence of the ambient irradiation (a) and of the cell temperature (b) on the
cell characteristics
Fig 2.5(a) shows that the open circuit voltage increases logarithmically with
the ambient irradiation, while the short circuit current is a linear function of the
ambient irradiation. The arrow shows in which sense the irradiation and the cell
temperature, respectively, increase. The influence of the cell temperature on the V-I
characteristics is illustrated in Figure 2.5(b). The dominant effect within-creasing
cell’s temperature is the linear decrease of the open circuit voltage, the cell being
thus less efficient. The short circuit current slightly increases with cell temperature.
For practical use, solar cells can be electrical connected in different ways: series or
parallel. Fig 2.6 presents how the V-I curve is modified in the case when two
identical cells are connected in series and in parallel.
 11

It is seen that V-I characteristics of series interconnected cells can be found

by adding, for each current, the different voltages of the individual cells.

On the other hand, for parallel cells the currents of the individual cells must
be added at each voltage in order to find the overall V-I curve.

Fig 2.6 (a) Series (b) parallel connection of identical cells.

SOLAR MODULE MODEL

Cells are normally grouped into “modules”, which are encapsulated with
various materials to protect the cells and the electrical connectors from the
environment. The manufacturers supply PV cells in modules, consisting of NPM
parallel branches, each with NSM solar cells in series, as shown in Fig 2.7. The PV
module consists of NPM parallel branches, each of NSM solar cells in series.
In order to have a clear specification of which element (cell or module) the
pa-ammeters in the mathematical model are regarding, the following notation is
used from now on: the parameters with superscript ”M ” are referring to the PV
module.
The parameters with superscript “C ” are referring to the solar cell. Thus, the
M
applied voltage at the module’s terminals is denoted by V , while the total
M
generated current by the module is denoted by I .
A model for the PV module is obtained by replacing each cell in Fig 2.7, by
the equivalent diagram from Fig 2.7. In the following, the mathematical model of a
PV module, suggested by (Lorenzo, 1994), is briefly reviewed. The advantage of
 12

this model is that it can be established applying only standard manufacturer

supplied data for the modules and cells.
M
The PV module’s current I under arbitrary operating conditions can thus be
described as:

Fig 2.7 The PV module consists of NPM parallel branches, each of NSM solar cells in
series.
ARRAY MODEL
The modules in a PV system are typically connected in arrays. Fig 2.8
illustrates the case of an array with MP parallel branches each with MS modules in
A
series. The applied voltage at the array’s terminals is denoted by V .
The total current of the array is denoted by

If it is assumed that the modules are identical and the ambient irradiation is
the same on all the modules, Then the array’s current is
 13

Fig 2.8 Solar cell array consists of Mp parallel branches, each with Ms Modules in
series.
BATTERY
Another important element of a stand-alone PV system is the battery. The
battery is necessary in such a system because of the fluctuating nature of the output
delivered by the PV arrays. Thus, during the hours of sunshine, the PV system is
directly feeding the load, the excess electrical energy being stored in the battery.
During the night, or during a period of low solar irradiation, energy is supplied to
the load from the battery.

CONTROLLER
This section presents the background behind the modelling of the controller
of a stand-alone PV system. All power systems must include a control strategy that
describes the interactions between its components. The use of battery as a storage
form implies thus the presence of a charge controller.
The charge controller is used to manage the energy flow to PV system,
batteries and loads by collecting information on the battery voltage and knowing the
maximum and minimum values acceptable for the battery voltage.
There are two main operating modes for the controller:
1) Normal operating condition, when the battery voltage fluctuates between
maximum and minimum voltages.
2) Overcharge or over-discharge condition, which occur when the battery
volt-age reaches some critical values.
 14

INVERTER
An inverter is a converter where the power flow is from the DC to the AC
side, namely having a DC voltage, as input, it produces a desired AC voltage.

ADVANTAGES OF STAND-ALONE PV SYSTEM

Stand-alone PV systems have got a number of advantages in comparison
with other sources of energy.
(1) Need any fuel to run the power generation process. The sunshine is abundant
in most of the places on earth at least for a few hours every day. This system
is completely nature-friendly and does not produce any waste or bi-product.
(2) Generate electricity where and when you need. It could be on a hilltop, on
the roof of your tree-house, on your boat and in all imaginable places the sun
can reach.
(3) The system is very simple, compact and modular. There is no complex
wiring, control system or infra-structure required.
(4) The Stand-alone PV system is easy and quick to install. You can dismantle
them easily, transport and install in a different location in a few hours.

APPLICATIONS OF STAND-ALONE PV SYSTEM

 Solar Energy For Battery Charging

 Power Your Home With Solar Energy
 Solar Energy For Cooking
 Power Pumps With Solar Energy
 15

CHAPTER -3

SYSTEM ANALYSIS

OPERATION PRINCIPLE
The proposed interleaved converter topology with high voltage transfer ratio
is proposed as shown in Fig 3.1. The proposed converter consists of two-phase
circuits with interleaved operation. The first phase is a boost integrating the
forward-type circuit structure, which includes inductor L1 and switch S1 for the
boost and an isolated forward energy-delivering circuit with turn ratio N. The
second phase of the proposed converter is a boost circuit which contains inductor
L2, switch S2, blocking capacitor C2, and diode D2 followed by the common
output capacitor Co.

Fig. 3.1. Proposed modular high step-up boost converter topology.

From Fig.3.1, one can see that the proposed converter is basically based on
the conventional voltage-doubler for the second phase circuit. However, for the first
phase, in order to reduce the voltage stress of switch S1 and diode D1, an additional
blocking capacitor C1, is added to function as that of C2 for the second phase. The
operation principle can be described by considering the key waveforms of the
proposed converter as shown in Fig.3.1. For simplicity, assume that all the
components in Fig.3.1 including the high-frequency transformer of the forward
energy delivering circuit are assumed ideal and under steady-state condition.
 16

As the main objective is to obtain high voltage gain and such characteristic is
achieved when the duty cycle is greater than 0.5, hence, the steady-state analysis is
made only for this case.
It is important to point out that the proposed high step-up converter can also
function for duty cycle lower than 0.5. However, with duty cycle lower than 0.5, the
secondary induction voltage of the transformer is lower, and consequently, it is not
possible to get the high voltage gain as that for duty ratio greater than 0.5.
As the fig. 3.1 to applying the ZVS to reduce the voltage stress of the
switches S1, S2.From Fig. 3.2, one can see that when the duty ratio is greater than
50%, there are four operation modes according to the ON/OFF status of the active
switches. Referring to the key waveforms shown in Fig. 3.2, the operating principle
of the proposed converter can be explained briefly as follows.

MODES OF OPERATION
Mode 1 [t0 < t ≤ t1]
From Fig. 3.2, one can see that for mode 1, switches S1, S2 are turned on.
Diode Df1 is forward biased, while diodes D1, D2, Df2 are reverse biased. During
this operation mode, both iL1 and iL2 are increasing to store energy in L1 and L2,
respectively. Meanwhile, the input power is delivered to the secondary side through
the coupled inductor and inductor Lf to charge capacitor C1. Also, the output power
is supplied from capacitor Co. The voltage across inductances L1 and L2 can be
represented as follows:

Mode 2 [t1 < t ≤ t2]

For this operation mode, switch S1 remains conducting, and S2 is turned off.
Also, diodes D1 and Df2 remain reverse biased; D2 and Df1 are forward biased.
The energy stored in inductor L2 is now released through C2 and D2 to the output.
However, the first phase circuit including the forward-type converter remains the
same.
 17

The voltage across inductances L1 and L2 can be represented as the following:

Mode 3 [t2 < t ≤ t3]

For this operation mode, both S1 and S2 are turned on. The corresponding
operating principle turns out to be the same as Mode 1.

Mode 4 [t3 < t ≤ t4]

During this operation mode, S1 is turned off, and S2 is turned on. Diode D2
and Df1 are reverse biased, and diode D1 is forward biased. Since diode Df1 is
reverse biased, diode Df2 must turn on to conduct the inductor current iLf.. The
energy stored in L1 is now released through C1 and D1 to charge capacitor C2 for
compensating the lost charges in previous modes. The energy stored in coupled
inductor is now treated to perform the self-resetting operation without additional
resetting winding. Also, the output power is supplied from capacitor Co. The
voltage across inductances L1 and L2 can be represented as follows:

STEADY-STATE ANALYSIS
The capacitor average voltage VC1 can be derived as follows, which is equal
to the average voltage across diode Df2:
 18

The average voltage across diode D1 can be described as

Fig.3.2. Key waveforms of the proposed converter

 19

From (6) and (7), the capacitor voltage VC2 can be obtained as follows:

The voltage conversion ratio of the proposed converter, it can be calculated

according to the volt-second balance principle of the boost inductors. From (1), (2)
and (4), the volt-second balance equation for boost inductor L1 becomes

Table 3.1 Gain and stress comparison for three converters

Thus, from (6), (8) and (9), the voltage conversion ratio M of the proposed
converter can be obtained as follows:

The open circuit voltage stress of switches S1 and S2 can be obtained

directly as follows:

It follows from (6), (8) and (10) that the same voltage stress is obtained for
both active switches as follows:
 20

For convenient comparison, the normalized voltage stress of the active

switches, namely MS, can be expressed as

In fact, one can see from (13) that the resulting voltage stress is obviously
smaller than VBus/2. Naturally, both conduction and switching losses can be
reduced as well. Similarly, the open circuit voltage stress of the corresponding
diodes can be expressed as follows:

It follows from (15) and (16) that the corresponding normalized voltage
stress becomes

Table 3.1 summarizes the voltage gain and normalized voltage stress of key
components of active as well as passive switches for reference. As an illustration,
Fig. 3.3 shows the characteristic analyses of the proposed converter. For
comparison, the voltage gains, switch stresses, and output diode stresses of the
conventional voltage-doubler and the conventional two phase interleaved boost
converter are also shown to provide better view. It is seen from Fig. 3.3(a) that,
much higher voltage gain can be achieved than that of the other two boost
converters.

As compared with conventional voltage-doubler and the conventional two-

phase interleaved boost converter, an additional voltage gain ND can be obtained
for the proposed converter by integrating the forward energy-delivering circuit.
 21

Also, it is seen that the proposed converter can achieve the lowest voltage stress for
the diodes.

As a result, one can expect that with proper design, the proposed converter
can adopt switch components with lower voltage ratings to achieve higher
efficiency.

Therefore mentioned steady-state continuous conduction mode (CCM)

analysis of the proposed converter is described in detail. It is particularly useful for
fuel cells and PV system applications.

As to the discontinuous conduction mode (DCM) operation, although it is

possible to yield a larger output voltage and a smaller duty cycle as compared to the
CCM operation, however, the resulting output voltage is more sensitive to changes
in duty cycle. Therefore, the design of the feedback circuit is more critical. In fact,
the peak-to-peak input current ripple in DCM is so large as to reduce the life time of
the fuel-cell stack and the extracted maximum power of PV system.

Fig.3.3. Characteristic analyses of the proposed converter:(a) Voltage

conversion ratio comparisons, (b) normalized switch voltage stress under different
voltage conversion ratio, and (c) normalized diode voltage stress under different
voltage conversion ratio.
 22

VOLTAGE STRESS OF THE POWER DEVICES

The voltage of the switched capacitor can be derived as

Vswc1 = (N + 1/1 – D ) Vin

It shows that the switched capacitor works like a dc source. Inserted between
the coupled inductor and the load. Voltage across the switched capacitor related to
the turns ratio and duty cycle. The voltage stress of the main switch is given by
converter at the same input voltage as well as the step-up voltage Because of the
extended voltage gain and reduced duty cycle , it is obvious that the switch voltage
stress is greatly reduced compared with the conventional ratio. The voltage stress of
the auxiliary switch is the same as that of the main switch.

V stress - main = (1/1 – D)Vin

MODELING OF THE PROPOSED MODULAR CONVERTER

The state-space averaged model of the proposed converter is derived under
the following assumptions: 1) power switches and diodes are ideal; 2) equivalent
series resistances (ESRs) of all inductors and capacitors of proposed converter are
considered to obtain a relatively precise dynamic model; 3) converter is operated
under CCM, and is in steady state. First, from Fig. 3.2, it is straightforward to find
that the corresponding weighting factors for the four operation modes are (d − 1/2),
(1 − d), (d − 1/2), and (1 − d) in sequence, respectively. Thus, one can apply the
state-space averaging technique to combine the state equations of different modes
into the following state-space averaged equation in matrix form as shown in (19),
where x is the state vector, matrices A, B, and C are constant matrices, u is the input,
and y is the output.

Where
 23

The corresponding state coefficient matrices A can be expressed as (21),

shown at the bottom of this page. The other state coefficient matrices are shown in

Then, perturb the averaged state equation to yield steady state (dc) as well as
dynamic (ac) linear terms and eliminate the higher order terms. Finally, the
corresponding dc and ac models of the proposed converter can therefore be
procured as well, respectively.

DC MODEL
To simplify the mathematics, relationships between ESRs of all inductors
and capacitors are assumed to be the same. Thus, one can get the operation point of
proposed converter. Considering the practical situation, main ESRs of all capacitors
Rc are much smaller than load resistance (R _ Rc).

AC MODEL
Similarly, the ac model of the proposed converter can be procured as
follows:

In (24), matrices B, C, and F are defined in (25)–(27), respectively.

 24

The corresponding state coefficient matrices A_and E can be expressed as

(28) and (29), shown at the bottom of the next page.

Again, considering all ESRs of inductors are assumed to be the same and
neglecting main ESRs of all capacitors.

PARALLEL OPERATION CONTROL

The module-paralleled converter configuration offers higher input and output
ripple frequency, and increased reliability. In order to satisfy the demands of low-
voltage and high-current distributed power sources, a two-module parallel high
step-up converter system is now given for demonstration. For convenient design of
the closed-loop controller, these two power modules are now assumed identical and
with paralleled operation without the inherent circulating current phenomenon, and
the simplified small-signal model of equivalent single module can therefore be
obtained. For direct control of the input current, current controller is necessary to
regulate the source current at desired value. Moreover, in order to effectively reduce
the input current ripple, equal current sharing between the two input inductors is
necessary. On the other hand, output voltage should be well regulated during the
load variations. Therefore, a closed-loop voltage controller with current sharing is
designed for the proposed converter.
 25

CHAPTER 4
Z- SOURCE INVERTER
4.1 INTRODUCTION
The main objective of static power converters is to produce an AC output
waveform from a dc power supply. Impedance source inverter is an inverter which
employs a unique impedance network coupled with the inverter main circuit to the
power source. This inverter has unique features in terms of voltage (both buck &
boost) compared with the traditional inverters. A two port network that consists of a
split-inductor and capacitors that are connected in X shape is employed to provide
an impedance source (Z-source) coupling the inverter to the dc source, or another
converter. The DC source/load can be either a voltage or a current source/load.
Therefore, the DC source can be a battery, diode rectifier, thyristor converter, PV
cell, an inductor, a capacitor, or a combination of those. Switches used in the
converter can be a combination of switching devices and anti-parallel diode as
shown in Fig. 4.1

Fig 4.1 Single phase full bridge Z source inverter

4.2. IMPEDANCE NETWORK

The Z-source concept can be applied to all DC-to-AC, AC-to- DC, AC-to-
AC and DC-to-DC power conversion. It consists of voltage source from the DC
supply, Impedance network, and three phase inverter and with AC motor load.
AC voltage is rectified to DC voltage by the single phase rectifier. In the
rectifier unit consist of six diodes, which are connected in bridge way. This
 26

rectified output DC voltage fed to the Impedance source network which consists of
two equal inductors (L3, L4) and two equal capacitors (C3, C4).The network
inductors are connected in series arms and capacitors are connected in diagonal
arms .

The impedance network is used to boost the input voltage depends upon the
boosting factor .This network also act as a second order filter .This network should
require less inductance and smaller in size. Similarly capacitors required less
capacitance and smaller in size. This impedance network, constant impedance
output voltage is fed to the single phase inverter main circuit. Depending upon the
Gating signal, the inverter operates and this output is fed to the 1-phase AC load or
AC motor/ micro grid.

EQUIVALENT CIRCUIT AND PRINCIPLE OF OPERATION

The Z-source inverter is analyzed using voltage source inverter. 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 input DC voltage. That is, the Z-source
inverter is a boost inverter that has a wide range of obtainable voltage. The
traditional V- and I-source inverters cannot provide such feature.

Fig 4.2 System configuration

The main feature of the Z-source is implemented by providing gate pulses

including the shoot-through pulses. Here how to insert this shoot through state
becomes the key point of the control methods. It is obvious that during the shoot-
through state, the output terminals of the inverter are shorted and the output voltage
to the load is zero.
 27

The output voltage of the shoot through state is zero, which is the same as
the traditional zero states, therefore the duty ratio of the active states has to be
maintained to output a sinusoidal voltage, which means shoot-through only replaces
some or all of the traditional zero states.

Let us briefly examine the Z-source inverter structure. In Fig.4. 2, the single-
phase Z-source inverter bridge has nine permissible switching states (vectors)
unlike the traditional single-phase V-source inverter that has eight. The traditional
single-phase V-source inverter has six active vectors when the DC voltage is
impressed across the load and two zero vectors when the load terminals are shorted
through either the lower or upper three devices, respectively. However, single-phase
Z-source inverter bridge has one extra zero state (or vector) when the load terminals
are shorted through both the upper and lower devices of any one phase leg (i.e.,
both devices are gated on), any two phase legs, or all single phase legs. This shoot-
through zero state (or vector) is forbidden in the traditional V-source inverter,
because it would cause a shoot-through. We call this third zero state (vector) the
shoot-through zero state (or vector), which can be generated by seven different
ways: shoot through via any one phase leg, combinations of any two phase legs, and
all single phase legs. The Z-source network makes the shoot-through zero state
possible. This shoot-through zero state provides the unique buck-boost feature to
the inverter. The Z-source inverter can be operated in three modes which are
explained in below.

Mode I:
In this mode, the inverter bridge is operating in one of the six traditional
active vectors; the equivalent circuit is as shown in figure 4.3.
 28

Fig.4.3 Equivalent Circuit of the ZSI in one of the Six Active States
The inverter bridge acts as a current source viewed from the DC link. Both
the inductors have an identical current value because of the circuit symmetry. This
unique feature widens the line current conducting intervals, thus reducing harmonic
current.

Mode II:
The equivalent circuit of the bridge in this mode is as shown in the fig. 4.4.

Fig. 4.4 Equivalent Circuit of the ZSI in one of the Two Traditional Zero States
The inverter bridge is operating in one of the two traditional zero vectors and
shorting through either the upper or lower three device, thus acting as an open
circuit viewed from the Z-source circuit. Again, under this mode, the inductor carry
current, which contributes to the line current’s harmonic reduction as shown in
below fig 4.5.

Fig. 4.5 Equivalent Circuit of the ZSI in the Non Shoot-Through States.

Mode III:

The inverter bridge is operating in one of the seven shoot-through states. The
equivalent circuit of the inverter bridge in this mode is as shown in the below fig
4.6.In this mode, separating the dc link from the ac line. This shoot-through mode to
be used in every switching cycle during the traditional zero vector period generated
 29

by the PWM control. Depending on how much a voltage boost is needed, the shoot-
through interval (T0) or its duty cycle (T0/T) is determined. It can be seen that the
shoot-through interval is only a fraction of the switching cycle.

Fig. 4.6 Equivalent Circuit of the ZSI in the Shoot-Through State

MODELLING OF Z-SOURCE INVERTER

Following the design guidelines presented in for a 1- phase ZSI operating

with a small ripple in capacitor voltage and inductor current, the capacitor and
inductor can be calculated as where ds is the average shoot-through period as a
ratio of period of ripples in the dc link (Ts) which is one half of the period of
switching of the inverter, kv and ki are ripple factors of capacitor voltage and
inductor current, Es is the average dc source voltage and I0 is the average dc current
supplied to the inverter.

C=I0 dS Ts /(2kvEs)
L=Es dS Ts /(2kiI0)

After that the conversion is completed (DC-AC) then, inverter is fed to the
single phase AC micro grid.

TOTAL HARMONIC DISTORTION

Total Harmonic Distortion (THD) is an amplifier or pre-
amplifier specification that compares the output signal of the amplifier with the input
signal and measures the level differences in harmonic frequencies between the two.
 30

The difference is called total harmonic distortion. When the total harmonic
distortion of an amplifier is measured, the difference in the level of the harmonics at
the output stage of the amp is compared to the level of the harmonics at the input
stage, and the difference is the extent of the distortion.

ADVANTAGES OF Z-SOURCE INVERTER

The following are the advantages of Z-source inverter when compared to the
two traditional inverters i.e. voltage source inverter and current source inverter.
(1) Secures the function of increasing and decreasing of the voltage in the one step
energy processing. (lower costs and decreasing losses)
(2) Resistant to short circuits on branches and to opening of the circuits.
(3) Improve resistant to failure switching and EMI distortions.
(4) Relatively simple start-up (lowered current and voltage surges).
(5) Provide ride-through during voltage sags without any additional circuits.
(6) Improve power factor reduce harmonic current and common-mode voltage.
(7) Provides a low-cost, reliable and highly efficient single stage for buck and
boost
conversions. Has low or no in-rush current compared to VSI.
 31

CHAPTER-5
SIMULATION RESULTS
GENERAL
Simulation has become a very powerful tool on the industry application as
well as in academics, nowadays. It is now essential for an electrical engineer to
understand the concept of simulation and learn its use in various applications.
Simulation is one of the best ways to study the system or circuit behavior without
damaging it .The tools for doing the simulation in various fields are available in the
market for engineering professionals. Many industries are spending a considerable
amount of time and money in doing simulation before manufacturing their product.
In most of the research and development (R&D) work, the simulation plays a very
important role. Without simulation it is quiet impossible to proceed further. It
should be noted that in power electronics, computer simulation and a proof of
concept hardware prototype in the laboratory are complimentary to each other.
However computer simulation must not be considered as a substitute for hardware
prototype. The objective of this chapter is to describe simulation of impedance
source inverter with R, R-L and RLE loads using MATLAB tool.

THE ROLE OF SIMULATION IN DESIGN

Electrical power systems are combinations of electrical circuits and electro
mechanical devices like motors and generators. Engineers working in this discipline
are constantly improving the performance of the systems. Requirements for
drastically increased efficiency have forced power system designers to use power
electronic devices and sophisticated control system concepts that tax traditional
analysis tools and techniques. Further complicating the analyst's role is the fact that
the system is often so nonlinear that the only way to understand it is through
simulation. Land-based power generation from hydroelectric, steam, or other
devices is not the only use of power systems. A common attribute of these systems
is their use of power electronics and control systems to achieve their performance
objectives.
 32

Sim Power Systems is a modern design tool that allows scientists and
engineers to rapidly and easily build models that simulate power systems. Sim
Power Systems uses the Simulink environment, allowing you to build a model using
simple click and drag procedures.
Not only can you draw the circuit topology rapidly, but your analysis of the
circuit can include its interactions with mechanical, thermal, control, and other
disciplines. This is possible because all the electrical parts of the simulation interact
with the extensive Simulink modeling library. Since Simulink uses MATLAB as its
computational engine, designers can also use MATLAB toolboxes and Simulink
block sets. Sim Power Systems and Sim Mechanics share a special Physical
Modeling block and connection line interface.

INTRODUCTION TO MATLAB
MATLAB is a high-performance language for technical computing. It
integrates computation, visualization, and programming in an easy-to-use
environment where problems and solutions are expressed in familiar mathematical
notation. Typical uses includes

1. Math and computation

2. Algorithm development
3. Data acquisition
4. Modeling, simulation, and prototyping
5. Data analysis, exploration, and visualization
6. Scientific and engineering graphics
7. Application development, including graphical user interface building

MATLAB is an interactive system whose basic data element is an array that

does not require dimensioning. This allows you to solve many technical computing
problems, especially those with matrix and vector formulations, in a fraction of the
time it would take to write a program in a scalar non interactive language such as C
or FORTRAN.The name MATLAB stands for matrix laboratory. MATLAB was
 33

originally written to provide easy access to matrix software developed by the

LINPACK and EISPACK projects.

MATLAB engines incorporate the LAPACK and BLAS libraries,

embedding the state of the art in software for matrix computation. MATLAB has
evolved over a period of years with input from many users. In university
environments, it is the standard instructional tool for introductory and advanced
courses in mathematics, engineering, and science. In industry, MATLAB is the tool
of choice for high-productivity research, development, and analysis.

MATLAB features a family of add-on application-specific solutions called

toolboxes. Very important to most users of MATLAB, toolboxes allow you to learn
and apply specialized technology. Toolboxes are comprehensive collections of
MATLAB functions (M-files) that extend the MATLAB environment to solve
particular classes of problems. Areas in which toolboxes are available include signal
processing, control systems, neural networks, fuzzy logic, wavelets, simulation, and
many others.

5.4. SIMULATION RESULT

Fig. 5.1 Simulation circuit of PV Panel

 34

Fig.5.2 Simulation circuit of high step – up interleaved boost converter (IBC)

Fig.5.3 Input voltage of high step – up interleaved boost converter

Fig.5.4 Output voltage of high step – up interleaved boost converter

 35

Fig.5.5 Output current of high step – up interleaved boost converter

Fig.5.6 Output power of high step – up interleaved boost converter

Fig.5.7 Simulation circuit of high step – up interleaved boost converter with motor
load
 36

Fig 5.8 Output speed and torque of motor

Fig.5.9 Simulation circuit of proposed system using R load

Fig 5.10 Input voltage of proposed system using R load

 37

Fig 5.11 Output voltage of proposed system using R load

Fig 5.12 Output current of proposed system using R load

Fig 5.13 Output power of proposed system using R load

 38

Fig 5.14 Shows the FFT analysis of ZSI and THD is 5.12%

Fig 5.15 Simulation circuit of Parallel connection IBC with Z source inverter
The above fig 5.15 shows the Parallel connection IBC with Z source
inverter to increase the power.
 39

Fig 5.16 Output power of Parallel connection IBC with Z source inverter using R
load

Fig.5.17 Simulation circuit of proposed system connected to grid

Fig 5.18 Output voltage of proposed system connected to grid

 40

Table 5.1 Efficiency of various input voltage

INPUT INPUT OUTPUT
EFFICIENCY
VOLTAGE POWER POWER
12 180 167 92.77777778
24 725 670 92.4137931
48 2925 2710 92.64957265
60 4575 4250 92.89617486
75 7000 6480 92.57142857

efficiency
93
92.9
92.8
92.7
92.6
92.5
92.4
92.3
92.2
92.1
1 2 3 4 5

efficiency

Fig 5.19 Efficiency of various input voltage

The above fig 5.19 shows the graphical representation of efficiencies
obtained for various input voltage.
 41

HARDWARE IMPLEMENTATION

fig5.20.Input of driver unit

fig.5.21 Output of driver unit

 42

fig.5.22 Output CRO reading of high step – up interleaved boost converter

fig.5.23 Output Multi meter reading of high step – up interleaved boost converter
 43

CHAPTER – 6
CONCLUSION

This project has presented the procedures for a new modular interleaved
boost converter (IBC) by integrating a forward energy-delivering circuit with a
voltage-doubler and Z-source inverter is proposed for achieving high step-up and
high-efficiency objective. The input source of the interleaved boost converter (IBC)
from the photo voltaic. Steady-state analysis is performed to show the merits of
the proposed converter topology. Soft switching technique is used to reduce the
voltage stress, switching loss and conduction loss. For further understanding the
dynamic characteristic for the proposed converter module, steady state and small-
signal models of this converter are derived. For higher power applications and
satisfying the demands of low-voltage and high-current distributed power sources, a
two-module parallel high step-up converter system is implemented. A Z-source
inverter is used to convert high step up AC voltage from high step up DC voltage to
the load/ micro grid applications. Experimental results show that the proposed high
step-up boost converter and z- source Inverter module achieve an efficiency of 93%
approximately.

The Basic circuit and modified circuit elements are designed using relevant
equations. The simulation circuits are developed using elements of simulink library.
The Simulation is successfully done and open loop simulation results are presented.

FUTURE SCOPE
The system can be extended for high voltage range or levels. Increase in
levels will sure the voltage gain and efficiency of the converter. The hardware
implementation of the proposed system will be done and the hardware result will be
verified.
 44

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