This paper presents performance characteristics of Z-source inverter (ZSI) fed Induction Motor (IM) drives. Z-Source inverter is a single stage converter which performs both buck-boost energy conversions using the LC impedance network. This reduces the voltage range of the capacitors used and also the cost of the proposed topology which is in turn used to control the speed of an induction motor which is used in many valuable industrial applications. The Z Source inverter is a combined inverter with an additional buck-boost feature and the proposed topology increases the efficiency of the circuit by reducing the voltage stress across the capacitors. The z-source inverter is very advantageous over traditional inverters and we can be employed all ac and dc power conversion applications. Z-source inverter can boost dc input voltage with no requirement of dc to dc boost converter or step up transformer hence overcoming output voltage limitation of voltage source inverter as well as lower cost. A comparison among conventional PWM inverter dc to dc boost PWM inverter and control circuit cost which are the main a power electronics system.

1. IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 10, 2015 | ISSN (online): 2321-0613
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Simulation of Z-Source Inverter Fed Three Phase Induction Motor Drive
Suneel kirar1
C.S. Sharma2
1
PG Scholar 2
Associate Professor
1,2
Department of Electrical Engineering
1,2
Samrat Ashok Technological Institute Vidisha, (M.P.) India
Abstract— This paper presents performance characteristics
of Z-source inverter (ZSI) fed Induction Motor (IM) drives.
Z-Source inverter is a single stage converter which performs
both buck-boost energy conversions using the LC
impedance network. This reduces the voltage range of the
capacitors used and also the cost of the proposed topology
which is in turn used to control the speed of an induction
motor which is used in many valuable industrial
applications. The Z Source inverter is a combined inverter
with an additional buck-boost feature and the proposed
topology increases the efficiency of the circuit by reducing
the voltage stress across the capacitors. The z-source
inverter is very advantageous over traditional inverters and
we can be employed all ac and dc power conversion
applications. Z-source inverter can boost dc input voltage
with no requirement of dc to dc boost converter or step up
transformer hence overcoming output voltage limitation of
voltage source inverter as well as lower cost. A comparison
among conventional PWM inverter dc to dc boost PWM
inverter and control circuit cost which are the main a power
electronics system.
Key words: Converter, current-source inverter, inverter,
voltage-source inverter, Z-Source inverter, Three phase
induction motor.
I. INTRODUCTION
Z-source inverter can boost dc input voltage with no
requirement of dc-dc boost converter or step up transformer,
hence overcoming output voltage limitation of traditional
voltage source inverter as well as lower its cost. 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 that is greater than the available dc bus
voltage. In addition, the reliability of the inverter is greatly
improved because the shoot-through can no longer destroy
the circuit.
There are two traditional converters: voltage-source
(or voltage-fed) and current-source (or current-fed)
converters (or inverters depending on power flow
directions). The gain of the inverter can be controlled by
using pulse width modulation. Z-Source Inverter for
induction motor drives. Z-Source Inverter can be applied to
the entire spectrum of power conversion. It is used as Boost-
Buck conversion where a capacitor and inductor are used. In
this thesis, the Z-Source Inverter is considered in place of
Voltage Source Inverter and Current Source Inverter.
II. Z SOURCE INVERTER
A unique impedance network is used in the z-
source inverter that consists of two identical inductors L1
and L2 alongwith two identical capacitors C1 and C2 that
couples the power supply circuit to the inverter circuit. The
shoot through period i.e., the time period when two switches
of the same leg are gated allows the voltage to be boosted to
the required value when the input dc voltage is not upto the
required level. Else otherwise, the shoot through state is not
used thus enabling the ZSI to operate as both a buck-boost
inverter unlike the traditional voltage source and the current
source inverters.
Fig. 1: Equivalent circuit of z-source inverter
The above figure shows the presence of the z source
impedance network preceding the inverter main circuit. The
diode is used to prevent the reverse flow of current in the
circuit. Fig 2a&2b represent the equivalent circuit of the Z
source network in shoot through and non shoot through
states respectively. The energy is stored in the inductors in
the shoot through state when both the switches on the same
leg of the inverter are gated. This energy is then transferred
in addition to the supply voltage to the load side when
normal gating of the inverter switches occur.
Fig. 2: Equivalent circuit of Z source inverter in (a).shoot
through state and (b) non shoot through state.
III. INDUCTION MOTOR
Induction motor has been used in the mainly in application
requiring a constant speed because conventional method of
their speed control has either been expensive or highly
inefficient. Variable speed applications have been
dominated by dc drive. Availability of thyristors, power
transistors, IGBT and GTO has allowed the development of
variable speed 1induction motor drive. The main drawback
of dc motor is the presence of commutated and brushes

2. Simulation of Z-Source Inverter Fed Three Phase Induction Motor Drive
(IJSRD/Vol. 3/Issue 10/2015/064)
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Three phase induction motors are the most widely
used in various industrial applications because of the
following properties –
1) Self starting property
2) Elimination of a starting device
3) Robust construction
4) Higher power factor and good speed regulation.
IV. CIRCUIT AND SIMULATION
Fig: 3- Simulation result of rectification.
Simulation is performed using MATLAB/SIMULINK
software. Simulink liabrary files include inbuilt models of
many electrical and electronic components and devices such
as diodes, MOSFETS, capacitors, inductors, motors, power
supplies. The circuit components are connected as per
design without error, parameters of all components are
configuration as per requirement and simulation is perform.
Maximum constant boost control with third harmonic
injection method is used PWM generation and simulation.
The complete simulation diagram is shown in the figure 5.2.
The component values of z-source inverter depend on
switching frequency only. For this circuit L1 = L2 = 8.5mH
and C1 = C2 = 250uF. The purpose of the system is to
produce 230V line to line voltage. For PWM generation the
carrier frequency is set to 10 kHz and modulation reference
signal frequency is set to 50Hz.
Fig. 4: Simulation of z-source inverter fed three phase induction motor

3. Simulation of Z-Source Inverter Fed Three Phase Induction Motor Drive
(IJSRD/Vol. 3/Issue 10/2015/064)
All rights reserved by www.ijsrd.com 269
Fig. 5: Input Waveform of Applied Ac Voltage.
Fig. 6: Output wave form of DC voltage.
Fig. 7: Waveform of stator current.

4. Simulation of Z-Source Inverter Fed Three Phase Induction Motor Drive
(IJSRD/Vol. 3/Issue 10/2015/064)
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Fig. 8: Load voltage waveform
Fig. 9: Rotor speed in rpm of induction motor.
V. CONCLUSION
This paper has proposed a Z – source inverter based
induction motor drive. This drive system has the advantages
of both PMBDCM and Z-source inverter. The system
configuration, operation principle and control method have
been analyzed in detail. And based on the equivalent
circuits, the mathematical model has been established by
state-space averaging method. Simulation results have
validated the preferred features as well as the possibility of
the proposed drive system. Additionally, the shortcoming of
switching loss has been discussed, and a possible
improvement method has been presented. A PWM control
method was carried out in this paper for z-source Inverter
fed induction motor drive. The output voltage obtained from
ZSI is not limited and can be boosted beyond the limit
imposed by conventional VSI
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