INDEX

S. Name of Experiments Page Date of Date of Sign

No. No. Experiment Submission

1 To discuss concept of Modeling and Simulation.

2 (A) To develop the simulation model of a half wave

uncontrolled rectifier and analyze its waveforms.
(B) To develop the simulation model of a half
wave-controlled rectifier and analyze its waveforms.

3 (A) To develop the simulation model of a full wave

uncontrolled rectifier and analyze its waveforms.
(B) To develop the simulation model of a full wave-
controlled rectifier and analyze its waveforms.

4 To develop the simulation model of a Chopper

controlled DC drive and analyze its operation.

5 To develop the simulation model for compensation

of reactive power using Thyristor Controlled
Reactor (TCR) and evaluate its performance.

6 To develop the simulation model for compensation

of reactive power using Thyristor Switched
Capacitor (TSC) and evaluate its performance.

7 To develop the simulation model of a Boost Power

Factor Corrector and evaluate its performance.

8 To develop the simulation model of an Induction

Motor Drive fed by a cascaded Multi-Level Inverter
and evaluate its performance.

1
EX 806 MODELLING AND SIMULATION LAB
 UNIVERSITY INSTITUTE OF TECHNOLOGY
RAJIV GANDHI PROUDYOGIKI VISHWAVIDYALAYA
B.TECH. (ELECTRICAL & ELECTRONICS ENGINEERING)

NAME OF COURSE: MODELLING AND SIMULATION LAB SEMESTER: VIII

COURSE CODE: EX 806

LIST OF EXPERIMENTS

S. No. NAME OF EXPERIMENT CO Nos.

1 To discuss concept of Modeling and Simulation. CO1

(A) To develop the simulation model of a half wave uncontrolled rectifier

and analyze its waveforms. CO1, CO2,
2
(B) To develop the simulation model of a half wave controlled rectifier CO3, CO4
and analyze its waveforms.
(A)To develop the simulation model of a full wave uncontrolled rectifier
and analyze its waveforms. CO1, CO2,
3
(B) To develop the simulation model of a full wave controlled rectifier CO3, CO4
and analyze its waveforms.
To develop the simulation model of a Chopper controlled DC drive and CO1, CO2,
4
analysis its operation. CO3, CO4

To develop the simulation model for compensation of reactive power CO1, CO2,
5
using Thyristor Controlled Reactor (TCR) and evaluate its performance. CO3, CO4

To develop the simulation model for compensation of reactive power CO1, CO2,
6
using Thyristor Switched Capacitor (TSC) and evaluate its performance. CO3, CO4

To develop the simulation model of a Boost Power Factor Corrector and CO1, CO2,
7
evaluate its performance. CO3, CO4

To develop the simulation model of an Induction Motor Drive fed by a CO1, CO2,
8
cascaded Multi-Level Inverter and evaluate its performance. CO3, CO4

2
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -1
Aim: To discuss concept of Modelling and Simulation.

Theory:
1. Concept: MATLAB (matrix laboratory) is a multi-paradigm numerical
computing environment and proprietary programming language developed by MathWorks.
MATLAB allows matrix manipulations, plotting of functions and data, implementation
of algorithms, creation of user interfaces, and interfacing with programs written in other languages,
including C, C++, C#, Java, Fortran and Python.
Although MATLAB is intended primarily for numerical computing, an optional toolbox uses
the MuPAD symbolic engine, allowing access to symbolic computing abilities. An additional
package, Simulink, adds graphical multi-domain simulation and model-based
design for dynamic and embedded systems.
Modeling and Simulation (M&S) is the use of models (e.g., physical, mathematical,
or logical representation of a system, entity, phenomenon, or process) as a basis for simulations to
develop data utilized for managerial or technical decision making.[1][2]
In the computer application of modeling and simulation a computer is used to build a mathematical
model which contains key parameters of the physical model. The mathematical model represents
the physical model in virtual form, and conditions are applied that set up the experiment of interest.
The simulation starts – i.e., the computer calculates the results of those conditions on the
mathematical model – and outputs results in a format that is either machine- or human-readable,
depending upon the implementation.
The use of M&S within engineering is well recognized. Simulation technology belongs to the tool
set of engineers of all application domains and has been included in the body of
knowledge of engineering management. M&S helps to reduce costs, increase the quality of
products and systems, and document and archive lessons learned. Because the results of a simulation
are only as good as the underlying model(s), engineers, operators, and analysts must pay particular
attention to its construction. To ensure that the results of the simulation are applicable to the real
world, the user must understand the assumptions, conceptualizations, and constraints of its
implementation. Additionally, models may be updated and improved using results of actual
experiments. M&S is a discipline on its own. Its many application domains often lead to the
assumption that M&S is a pure application. This is not the case and needs to be recognized by
engineering management in the application of M&S.
The use of such mathematical models and simulations avoids actual experimentation, which can be
costly and time-consuming. Instead, mathematical knowledge and computational power is used to
solve real-world problems cheaply and in a time efficient manner. As such, M&S can facilitate
understanding a system's behavior without actually testing the system in the real world. For
example, to determine which type of spoiler would improve traction the most while designing a
race car, a computer simulation of the car could be used to estimate the effect of different spoiler

3
EX 806 MODELLING AND SIMULATION LAB
shapes on the coefficient of friction in a turn. Useful insights about different decisions in the design
could be gleaned without actually building the car. In addition, simulation can support
experimentation that occurs totally in software, or in human-in-the-loop environments where
simulation represents systems or generates data needed to meet experiment objectives. Furthermore,
simulation can be used to train persons using a virtual environment that would otherwise be difficult
or expensive to produce.
2. Model and simulate dynamic system behavior with MATLAB, Simulink, State
flow, and Simscape
Modeling is a way to create a virtual representation of a real-world system that includes software
and hardware. If the software components of this model are driven by mathematical relationships,
you can simulate this virtual representation under a wide range of conditions to see how it behaves.

Modeling and simulation are especially valuable for testing conditions that might be difficult to
reproduce with hardware prototypes alone, especially in the early phase of the design process when
hardware may not be available. Iterating between modeling and simulation can improve the quality
of the system design early, thereby reducing the number of errors found later in the design process.

Common representations for system models include block diagrams, schematics, and state
diagrams. Using these representations you can model mechatronic systems, control
software, signal processing algorithms, and communications systems. To learn more about
modeling and simulation with block diagrams, see Simulink®.

3.FACTS
FACTS is defined as "a power electronic based system and other static equipment that
provide control of one or more AC transmission system parameters to enhance
controllability and increase power transfer capability.”
The FACTS technology is not a single high power controller, but rather a collection of
controllers, which can be applied individually or in coordination with others to control one
or more interrelated system parameters. FACTS technology also lends itself to extending
usable transmission limits in a step-by-step manner with incremental investment as and
when required.

3.1 FACTS CONTROLLERS

Generally, the main objectives of FACTS controllers are to increase the useable
transmission capacity of lines and control power flow over designated transmission routes.
FACTS technology opens up new opportunities for controlling and enhancing the useable
capacity of present, as well as new upgraded lines. FACTS is an evolving technology and
can boost power transfer capability by 20–30% by increasing the flexibility of the systems.

By providing added flexibility, FACTS controllers can enable a line to carry power closer
to its thermal rating. FACTS device offers continuous control of power flow or voltage,
against daily load changes or change in network topologies.

4
EX 806 MODELLING AND SIMULATION LAB
There are two generations for realization of power electronics-based FACTS controllers:
1.) First Generation FACTS Controllers (Thyristor Based Controllers)
2.) Second Generation FACTS Controllers (Converter Based Controllers)

In these systems, the use of static VAR compensators with fast response times play
an important role, allowing to increase the amount of apparent power transfer through
an existing line, close to its thermal capacity, without compromising its stability
limits. These opportunities arise through the ability of special static VAR
compensators to adjust the interrelated parameters that govern the operation of
transmission systems, including series impedance, shunt impedance, current,
voltage, phase angle and the damping of oscillations at variable frequency below the
rated frequency.
The two groups of FACTS controllers have distinctly different operating and
performance characteristics.

3.2 FIRST GENERATION FACTS CONTROLLERS

The First generation employs conventional thyristor-switched capacitors and
reactors, and quadrature tap-changing transformers. The first generation has resulted
in the Static Var Compensator (SVC), the Thyristor- Controlled Series Capacitor
(TCSC), and the Thyristor-Controlled Phase Shifter (TCPS).
The thyristor-controlled group employs capacitor and reactor banks with fast solid-
state switches in traditional shunt or series circuit arrangements. The thyristor
switches control the on and off periods of the fixed capacitor and reactor banks and
thereby realize a variable reactive impedance. Except for losses, they cannot
exchange real power with the system.

3.3 SECOND GENERATION FACTS CONTROLLERS

The Second generation employs gate turn-off (GTO) thyristor-switched converters
as voltage source converters (VSCs). The second generation has produced the Static
Synchronous Compensator (STATCOM), the Static Synchronous Series
Compensator (SSSC), the Unified Power Flow Controller (UPFC), and the Interline
Power Flow Controller (IPFC).
The voltage source converter type FACTS controller group employs self-
commutated DC to AC converters, using GTO thyristors, which can internally
generate capacitive and inductive reactive power for transmission line compensation,
without the use of capacitor or reactor banks. The converter with energy storage
device can also exchange real power with the system, in addition to the independently
controllable reactive power. The VSC can be used uniformly to control transmission

5
EX 806 MODELLING AND SIMULATION LAB
 line voltage, impedance, & angle by providing reactive shunt compensation, series
compensation, and phase shifting, or to control directly the real & reactive power
flow in the line.

3.4 VARIOUS FACTS CONTROLLERS

A.) Static VAR Compensator (SVC):-
It is used to improve the dynamic stability performance of a power system. SVCs
have been applied successfully to improve the transient stability of a synchronous
machine. It is shown that the SVC enhances the system damping of local as well as
interarea oscillation modes. Self-tuning and model reference adaptive stabilizers for
SVC control have been also proposed and designed.
B.) Thyristor-Controlled Series Capacitor (TCSC):-
TCSC is one of the most important and best known series facts controller. It has been
in use for many years to increase line power transfer as well as to enhance system
stability. Basically a TCSC consists of three components: capacitor banks C, by pass
inductor L and bidirectional thyristors.
C.) Thyristor-Switched Capacitors (TSC):-
The shunt capacitor bank is split up into appropriately small steps, which are
individually switched in and out using bidirectional thyristor switches. Each single-
phase branch consists of two major parts, the capacitor C and the thyristor switches
Sw1 and Sw2. In addition, there is a minor component, the inductor L, whose purpose
is to limit the rate of rise of the current through the thyristors and to prevent resonance
with the network (normally 6% with respect to Xc).
D.) Thyristor-Controlled Reactor (TCR):-
Each of the three phase branches includes an inductor L, and the thyristor switches
Sw1 and Sw2. Reactors may be both switched and phase-angle controlled. When
phase-angle control is used, a continuous range of reactive power consumption is
obtained. It results, however, in the generation of odd harmonic current components
during the control process. Full conduction is achieved with a gating angle of 90°.
E.) Thyristor-Controlled Phase Shifter (TCPS): -
In their control scheme the phase shift angle is determined as a nonlinear function of
rotor angle and speed. However, in real-life power system with a large number of
generators, the rotor angle of a single generator measured with respect to the system
reference will not be very meaningful.

F.) Static Compensator (STATCOM):-

6
EX 806 MODELLING AND SIMULATION LAB
 STATCOM provides better damping characteristics than the SVC as it is able to
transiently exchange active power with the system. However, the effectiveness of the
STATCOM to enhance the angle stability has not been addressed. STATCOM-based
damping stabilizers extend the critical clearing time and enhance greatly the power
system transient stability.
G.) Static Synchronous Series Compensator (SSSC): -
The SSSC has been applied to different power system studies to improve the system
performance. There has been some work done to utilize the characteristics of the
SSSC to enhance power system stability. The effectiveness of the SSSC to extend
the critical clearing time has been confirmed though simulation results on a single
machine infinite bus system.
H.) Unified Power Flow Controller (UPFC): -
A unified power flow controller (UPFC) is the most promising device in the FACTS
concept. It has the ability to adjust the three control parameters, i.e. the bus voltage,
transmission line reactance, and phase angle between two buses, either
simultaneously or independently. A UPFC performs this through the control of the
in-phase voltage, quadrature voltage, and shunt compensation. A UPFC can control
the three control parameters either individually or in appropriate combinations at its
series-connected output while maintaining reactive power support at its shunt-
connected input.
3.5 TYPES OF FACTS CONTROLLERS
In general FACTS controllers can be divided into the following four categories:
A. SERIES CONTROLLERS: -
In principle all the series controllers inject voltage in series with the line. Series
connected controller impacts the driving voltage and hence, the current and power
flow directly. Static Synchronous Series Compensator (SSSC), Thyristor Controlled
Series Compensator (TCSC) etc. are the examples of series controllers.
B. SHUNT CONTROLLERS: -
All shunt controllers inject current into the system at the point of connection. The
shunt controller is like a current source, which draws/injects current from/into the
line. Static Synchronous Compensator (SSC), Static Synchronous Generator (SSG),
Thyristor Controlled Reactor (TCR) etc are the examples of shunt controllers.
C. COMBINED SERIES-SHUNT CONTROLLERS: -
This could be a combination of separate shunt and series controllers, which are
controlled in a coordinated manner. Combined shunt and series controllers inject
current into the system with the shunt part of the controller and voltage in series in
the line with the series part of the controller. Unified Power Flow Controller (UPFC)

7
EX 806 MODELLING AND SIMULATION LAB
 and Thyristor Controlled Phase Shifting Transformer (TCPST) are the examples of
shunt series controllers.
D. COMBINED SERIES-SERIES CONTROLLERS: -
This could be a combination of separate series controllers, which are controlled in a
coordinated manner, in a multi-line transmission system or it could be a unified
controller, in which series controller provides independent series reactive
compensation for each line but also transfer real power among the line via the power
link.

A) Series Compensation B) Shunt Compensation

FIG.1.1 SERIES AND SHUNT COPENSATION

3.6 MODELLING OF STATIC COMPENSATORS

Electrical Power systems are combinations of electrical circuits, and

electromechanical devices, like motors and generators. The blockset uses a Simulink
environment, allowing a model to be built using click & drag procedure. The power
system block set has been designed to simulate power electronic devices.

8
EX 806 MODELLING AND SIMULATION LAB
 TCR TSC
Branch Branch

FIG.1.2 SINGLE LINE DIAGRAM OF STATIC COMPENSATOR

Consider a circuit, representing one phase of static var compensator (SVC) used on
a 735 KV transmission network. On the secondary of the 735 KV/ 16 KV
transformer, two variable susceptance branches are connected in parallel: one
thyristor-controlled reactor (TCR) branch and one thyristor switched capacitor (TSC)
branch.

The TCR and TSC branches are both controlled by a valve consisting of two thyristor
strings connected in antiparallel. An RC snubber circuit is connected across each
valve. The TSC branch is switched on/off, thus providing discrete step variation of
SVC capacitive current. The TCR branch is phase controlled in order to obtain a
continuous variation of the net SVC reactive current.

9
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -2

Aim: (a)To develop the simulation model of a half wave uncontrolled rectifier
and analyze its waveforms.
SOFTWARE REQUIRED: MATLAB 2013, SIMULINK Library.
THEORY:
A half wave rectifier is a type of rectifier which allows only half cycle (either positive half cycle or
negative half cycle) of the input AC signal while another half cycle is blocked.

Values:
Voltage=230*1.414 Resistance=10ohm Inductance=0.001H

SIMULINK MODEL:
a. For R Load

10
EX 806 MODELLING AND SIMULATION LAB
 RESULTS:

b. For L Load

11
EX 806 MODELLING AND SIMULATION LAB
 RESULTS:

c. For RL Load

12
EX 806 MODELLING AND SIMULATION LAB
 RESULTS:

CONCLUSION: The half wave rectification is obtained.

13
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -2

Aim: (b) To develop the simulation model of a half wave-controlled rectifier and
analyze its waveforms.
INTRODUCTION:

Power electronics technology encompasses the use of electronic components, the application of
circuit theory and design techniques, and the development of analytical tools toward efficient
electronic conversion, control, and conditioning of electric power. The typical undergraduate
syllabus will have topics like: uncontrolled and controlled rectifiers with R, RL loads; choppers;
single-phase and 3-phase inverters; AC voltage controllers, etc. [1]. The basic information of
MATLAB i.e. what is MATLAB, MATLAB Toolbox & SIMULINK, MATLAB Advantages & its
application, is presented in [2]. In this paper the characteristics of SCR, simulation of single-phase
half wave & full wave controlled & uncontrolled rectifiers are presented on MATLAB software.

MATLAB/SIMULINK FOR POWER ELECTRONICS:

The following section will look at how the modeling and simulation of a power electronic converter
can be carried out using MATLAB/SIMULINK software. Firstly, open MATLAB then
SIMULINK. A SIMULINK library browser will open from this select the blocks which are used to
achieve the modeling as follow: first from SIMULINK from commonly used blocks we choose
scope (used for show output waveform), bus selector (used for measure signal for example voltage
and current waveform in case of diode or SCR) from sources choose pulse generator (used to
providing pulse for GATE of THYRISTOR). In SIMULINK library browser Sim power systems is
first chosen & select powerugi (used to select the supply type i.e. continues or discrete). In Sim
power systems various sub library are present for electrical engineering application. From power
electronics choose THYRISTOR, MOSFET, GTO etc. Power electronics devices from electrical
sources choose supply i.e. AC /DC voltage supply. Then from elements choose RLC series branch
for R, L, C, RL, RC or RLC load. Then from measurement choose current & voltage measurement.
All the blocks listed above are used in this paper for simulation purpose. By right click we can
change the property of blocks. Fig. 1 show the all blocks listed above.

14
EX 806 MODELLING AND SIMULATION LAB
Values:
Voltage=230*1.414 Resistance=30ohm Inductance=0.03H

SIMULINK MODEL:
a. For RL Load

RESULTS:

15
EX 806 MODELLING AND SIMULATION LAB
 b. For L load

RESULTS:

16
EX 806 MODELLING AND SIMULATION LAB
 c. For R load

RESULTS:

CONCLUSION:
The following conclusion may be derived when using SIMULINK in teaching power electronics
courses: As power electronic systems are getting more complex today, the simulation used for
education is requiring more features. Some directions in the development of simulation are
discussed in this paper, with the help of present model students can simulate the power electronics
circuit with various load & conditions.

17
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -3

Aim: (a) To develop the simulation model of a full wave uncontrolled rectifier
and analyze its waveforms.
SOFTWARE REQUIRED: MATLAB 2013, SIMULINK Library.
THEORY:
Like the half wave circuit, a full wave rectifier circuit produces an output voltage or current which
is purely DC or has some specified DC component. Full wave rectifiers have some fundamental
advantages over their half wave rectifier counterparts. The average (DC) output voltage is higher
than for half wave, the output of the full wave rectifier has much less ripple than that of the half
wave rectifier producing a smoother output waveform.
In a Full Wave Rectifier circuit two diodes are now used, one for each half of the cycle. A multiple
winding transformer is used whose secondary winding is split equally into two halves with a
common centre tapped connection, (C). This configuration results in each diode conducting in turn
when its anode terminal is positive with respect to the transformer centre point C producing an
output during both half-cycles, twice that for the half wave rectifier so it is 100% efficient as shown
below.

Full Wave Rectifier Circuit

The full wave rectifier circuit consists of two power diodes connected to a single load resistance (RL) with
each diode taking it in turn to supply current to the load. When point A of the transformer is positive with
respect to point C, diode D1 conducts in the forward direction as indicated by the arrows.

18
EX 806 MODELLING AND SIMULATION LAB
When point B is positive (in the negative half of the cycle) with respect to point C, diode D2 conducts in the
forward direction and the current flowing through resistor R is in the same direction for both half-cycles. As
the output voltage across the resistor R is the phasor sum of the two waveforms combined, this type
of full wave rectifier circuit is also known as a “bi-phase” circuit.

Values:
Voltage=230*1.414 Resistance=30ohm Inductance=0.03H

SIMULINK MODEL:

a. For R Load

RESULTS:

19
EX 806 MODELLING AND SIMULATION LAB
b. For L Load

RESULTS:

20
EX 806 MODELLING AND SIMULATION LAB
 c. For RL Load

RESULTS:

CONCLUSION: The output waveform of full wave center-tapped rectifier was obtained.

21
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -3

Aim: (b) To develop the simulation model of a full wave-controlled rectifier and
analyze its waveforms.

INTRODUCTION:

Power electronics technology encompasses the use of electronic components, the application of
circuit theory and design techniques, and the development of analytical tools toward efficient
electronic conversion, control, and conditioning of electric power. The typical undergraduate
syllabus will have topics like: uncontrolled and controlled rectifiers with R, RL loads; choppers;
single-phase and 3-phase inverters; AC voltage controllers, etc. [1]. The basic information of
MATLAB i.e. what is MATLAB, MATLAB Toolbox & SIMULINK, MATLAB Advantages & its
application, is presented in [2]. In this paper the characteristics of SCR, simulation of single phase
half wave & full wave controlled & uncontrolled rectifiers are presented on MATLAB software.

MATLAB/SIMULINK FOR POWER ELECTRONICS:

The following section will look at how the modeling and simulation of a power electronic converter
can be carried out using MATLAB/SIMULINK software. Firstly, open MATLAB then
SIMULINK. A SIMULINK library browser will open from this select the blocks which are used to
achieve the modeling as follow: first from SIMULINK from commonly used blocks we choose
scope (used for show output waveform), bus selector (used for measure signal for example voltage
and current waveform in case of diode or SCR) from sources choose pulse generator (used to
providing pulse for GATE of THYRISTOR). In SIMULINK library browser Sim power systems is
first chosen & select powerugi (used to select the supply type i.e. continues or discrete). In Sim
power systems various sub library are present for electrical engineering application. From power
electronics choose THYRISTOR, MOSFET, GTO etc. Power electronics devices from electrical
sources choose supply i.e. AC /DC voltage supply. Then from elements choose RLC series branch
for R, L, C, RL, RC or RLC load. Then from measurement choose current & voltage measurement.
All the blocks listed above are used in this paper for simulation purpose. By right click we can
change the property of blocks. Fig. 1 show the all blocks listed above.

22
EX 806 MODELLING AND SIMULATION LAB
Values:
Voltage=230*1.414 Resistance=100 Inductance=3mH
SIMULINK MODEL:
a. For R Load

RESULTS:

23
EX 806 MODELLING AND SIMULATION LAB
 b. For L Load

RESULTS:

24
EX 806 MODELLING AND SIMULATION LAB
 c. For RL Load

RESULTS:

a. For α=0o

25
EX 806 MODELLING AND SIMULATION LAB
b. For α=30o

c. For α=45o

26
EX 806 MODELLING AND SIMULATION LAB
d. For α=60o

e. For α=90o

27
EX 806 MODELLING AND SIMULATION LAB
CONCLUSION:
The following conclusion may be derived when using SIMULINK in teaching power electronics
courses: As power electronic systems are getting more complex today, the simulation used for
education is requiring more features. Some directions in the development of simulation are
discussed in this paper, with the help of present model students can simulate the power electronics
circuit with various load & conditions.

28
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -4

Aim: To develop the simulation model of a Chopper controlled DC drive and

analysis its operation.
THEORY:
Dc converters can be used as switching mode regulators to convert a dc voltage, normally
unregulated, to a regulated dc output voltage. The regulation is normally achieved by PWM at a
fixed frequency and the switching device is normally BJT, MOSFET or IGBT. The elements of
switching mode regulators are shown in Fig2(a). The designer can select the switching frequency
by choosing the values of R and C of frequency oscillator. Control voltage Vc is obtained by
comparing the output voltage with its desired value. The Vcr can be compared with a sawtooth
voltage Vr to generate the PWM control signal for the dc converter. Four basic topologies of
switching regulators are –
1) Buck regulators
2) Boost regulators
3) Buck – boost regulators
4) Cuk regulators

Input Output
+ DC Chopper +

vg Va
Vs
vr vcr ve vref
Control
Amplifier Reference
- -

Fig 4(a) –Elements of switching mode regulator.

Buck Regulators
In a buck regulator, the average output voltage Va is less than the input voltage, Vs hence the name
“buck”. The circuit diagram of a buck regulator using a power BJT is shown in Fig 2(b) and this is
like a step down converter. The circuit operation can be divided into two modes. Mode 1 begins
when transistor Q1 is switched on ,the input current , which rises flows through filter inductor L ,
filter capacitor C ,and load resister R .Mode 2 begins when transistor Q1 is switched off ,the
freewheeling diode Dm conducts due to energy stored in the inductor , and the inductor current
continues to flow through L,C, load and diode Dm.The inductor current falls until transistor Q1 is
switched on again in next cycle. Depending on the switching frequency, filter inductance, and
capacitance the inductor current could be discontinuous.

29
EX 806 MODELLING AND SIMULATION LAB
 + eL -
is , Is Q1 L
+
iL , IL io , Ia +
ic , Ic

Vs Dm Load
vo,Va
Control
-
-

Fig 4(b)- Circuit diagram of Buck Regulator

Boost Regulators
In boost regulator the output voltage is greater than the input voltage hence the name “boost”. A
boost regulator using a power MOSFET is shown in Fig 2(c). The circuit operation can be divided
into two modes. Mode 1 begins when transistor M1 is switched on, the input current, which rises,
flows through inductor L and transistor Q1. Mode 2 begins when transistor M1 is switched off. The
current that was flowing through the transistor would now flow through L, C, load, and diode Dm.
The inductor current falls until transistor M1 is turned on again in the next cycle. The energy stored
in inductor L is transferred to the load.

+ eL - iL , IL Dm
is , Is i1
+
+ + io , Is+
L
+
C
Vs M vD vc Load vo,Va

G
- - -
-

Fig 4(c)- Circuit diagram of Boost Regulator

Buck- Boost Regulators
A buck boost regulator provides an output voltage that may be less than or greater than the input
voltage hence the name “buck-boost” ,the output voltage polarity is opposite to that of the input
voltage. The circuit diagram of a buck-boost regulator is shown in Fig 2(d). The circuit operation
can be divided into two modes. Mode 1 begins when transistor Q1 is turned on and diode Dm is
reversed biased .The input current which rises flows through inductor L and transistor Q1.During
Mode 2 transistor Q1 is switched off and current, which was flowing through L , would flow through
L , C, Dm and load .The energy stored in inductor L would be transferred to the load and the inductor
current would fall until transistor Q1 is switched on again in the next cycle.

30
EX 806 MODELLING AND SIMULATION LAB
 Dm
Q1
vD
+
- +
i1
vc=-vo
Vs GM L Load vo Va
C

iL , IL iC
+ -
-

Fig 4(d)- Circuit diagram of Buck-Boost Regulator

Cuk Regulators
The circuit arrangement of the cuk regulator using a power BJT is shown in Fig 2(e). It provides an
output voltage that may be less than or greater than the input voltage, the output voltage polarity is
opposite to that of the input voltage. When the input voltage is turned on and transistor Q1 is
switched off, diode Dm is forward biased and capacitor C1 is charged through L1, Dm, and the input
supply Vs. The circuit operation can be divided into two modes. Mode 1 begins when transistor Q1
is turned on, current through inductor L1 rises. At the same time the voltage of capacitor C1 reverse
biases Dm and turns it off. The capacitor C1 discharges its energy to the circuit formed by C1, C2
and load and L2. Mode 2 begins when transistor Q1 is turned off. The capacitor C1 is charged from
the input supply and the energy stored in the inductor L2 is transferred to the load. The diode Dm
and transistor Q1 provide a synchronous switching action.

iL1, is + eL - C1 ic1 IL2

+
iL1, is + + L2 - ++
L1 Vc1

Vs VT Vdm Dm Vc2 Load vo,Va

C2

G Q1 iC2

- - - + io= ia -
-

Fig 4(e)- Circuit diagram of Cuk Regulator

31
EX 806 MODELLING AND SIMULATION LAB
SIMULINK MODEL & GRAPH:

RESULT:

32
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -5

Aim: To develop the simulation model for compensation of reactive power using
Thyristor Controlled Reactor (TCR) and evaluate its performance.

SOFTWARE REQUIRED: MATLAB 2013, SIMULINK Library.

THEORY: MODELLING OF THYRISTOR CONTROLLED REACTOR (TCR)

The ability of an FC-TCR (fixed-capacitor thyristor-controlled reactor) compensator to

change its reactive power within the theoretical time of half a period requires, as a
prerequisite, the setting up of a proper control function. In other words, the firing angle α
of the thyristors in antiparallel has to be related to properly detectable input variables, i.e.
load reactive power. This comes in the category of shunt compensator.

The theoretical and computer-simulation approaches to this problem are examined and
compared. The equations describing the relation between α and the load reactive power are
introduced. The whole system is then modeled and simulated by computer, and the results
are compared with the theoretical ones.

The control curves obtained theoretically agree well with those obtained by simulation. It
is concluded that the proposed analytical approximating equation offers quite good results
for practical purposes. The fixed control thyristor-controlled reactor is a var generator
arrangement using a fixed capacitance with a thyristor-controlled reactor. The model of FC-
TCR with the line voltage of 16 kV is shown.

In this TCR modeling, the firing angle is varied and for different angles of firing angles,
the value of Active & Reactive power are observed along with the voltage and current
waveforms of source and thyristor and are analyzed. This can be done by applying a formula
for both the thyristors i.e. for changing the firing angle of thyristors T1 & T2.
Thyristor 1, T1= 1/50 + T
Thyristor 2, T2= 1/50 + 1/100 + T

where T= Time period (for eg. For firing angle of 150°, T=1/150)

SIMULINK MODEL OF TCR

33
EX 806 MODELLING AND SIMULATION LAB
FIG.4.1 MODEL OF TCR (MAIN SYSTEM)

FIG.4.2 MODEL OF TCR (SUB SYSTEM)

RESULTS OF TCR

Firing angle =120°

I) Source voltage and current

34
EX 806 MODELLING AND SIMULATION LAB
 II) Primary current

load iprim.mat
a=iprim
t=a(1,:)
plot (t,a)

III) Active & Reactive Power

IV) Voltage & Current for Thyristor 1

35
EX 806 MODELLING AND SIMULATION LAB
V) Voltage & Current for Thyristor 2

Firing angle =150°

I) Source voltage and current

36
EX 806 MODELLING AND SIMULATION LAB
II) Primary current
load iprim.mat
a=iprim
t=a(1,:)
plot (t,a)

III) Active & Reactive Power

IV) Voltage & Current for Thyristor 1

37
EX 806 MODELLING AND SIMULATION LAB
V) Voltage & Current for Thyristor 2

Firing angle =180°

I) Source voltage and current

II) Primary current

load iprim.mat
a=iprim
t=a(1,:)
plot (t,a)

38
EX 806 MODELLING AND SIMULATION LAB
III) Active & Reactive Power

IV) Voltage & Current for Thyristor 1

V) Voltage & Current for Thyristor 2

39
EX 806 MODELLING AND SIMULATION LAB
 Firing angle =210°

I) Source voltage and current

II) Primary current

load iprim.mat
a=iprim
t=a(1,:)
plot (t,a)

III) Active & Reactive Power

40
EX 806 MODELLING AND SIMULATION LAB
IV) Voltage & Current for Thyristor 1

V) Voltage & Current for Thyristor 2

41
EX 806 MODELLING AND SIMULATION LAB
 Firing angle =240°
I) Source voltage and current

II) Primary current

load iprim.mat
a=iprim
t=a(1,:)
plot (t,a)

III) Active & Reactive Power

42
EX 806 MODELLING AND SIMULATION LAB
IV) Voltage & Current for Thyristor 1

V) Voltage & Current for Thyristor 2

43
EX 806 MODELLING AND SIMULATION LAB
PROGRAMMING OF TCR

Source Voltage & Current

load visource.mat load iprim.mat

a=vi b=iprim
t=a(1,:) t=b(1,:)
plot (t,a) plot (t,b)

Active & Reactive Power

load active.mat load reactive.mat

c=p d=q
t=c(1,:) t=d(1,:)
plot (t,c) plot (t,d)

Voltage & Current For Thyristor 1

load volts1.mat load curr1.mat

a=vt b=ct
t=a(1,:) t=b(1,:)
plot (t,a) plot (t,b)

Voltage & Current For Thyristor 2

load volts2.mat load curr2.mat

c=vt d=ct
t=c(1,:) t=d(1,:)
plot (t,c) plot (t,d)

44
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -6

Aim: To develop the simulation model for compensation of reactive power using
Thyristor Switched Capacitor (TSC) and evaluate its performance.

SOFTWARE REQUIRED: MATLAB 2013, SIMULINK Library.

THEORY: MODELLING OF THYRISTOR SWITCHED CAPACITOR (TCR)

In a static var generator for providing reactive power compensation to a ac network and
including a thyristor switched capacitor bank having a series combination of a capacitor, a
bidirectional switch having gate drive, and a current limiting inductor with an applied
voltage appearing across the combination with a current being conducted there through, a
damping circuit and method for switching the thyristor switch to achieve damping of
oscillatory transients generated by the switching of the capacitor in the network, comprising
of :

• Determining the magnitude and polarity of the voltage difference between the
applied voltage and the voltage across the capacitor;
• Determining the occurrence of the prepeak quadrant and the postpeak quadrant
of the applied voltage.

Like, TCR this is also a shunt compensator. In this TCR modeling, the firing angle is varied
and for different angles of firing angles, the value of Active & Reactive power are observed
along with the voltage and current waveforms of source and thyristor and are analyzed.
This can be done by applying a formula for both the thyristors i.e. for changing the firing
angle of thyristors T1 & T2. Here, both the thyristors are triggered at the same time. A step
wave is given as the input pulse for both the thyristors T1 and T2. The step time is defined
in the step wave input. The model of TSC with the line voltage of 16 kV is shown.

T=1/50/4 or T=1/50/8

A power GUI Discrete system is also placed in the system such that the value of initial state
setting is changed. It is different for both initial and final value of capacitor voltage.

45
EX 806 MODELLING AND SIMULATION LAB
SIMULINK MODEL OF TCR

FIG.6.1 MODEL OF TSC (MAIN SYSTEM)

FIG.5.2 MODEL OF TSC (SUB SYSTEM)

RESULTS OF TSC
Step Pulse = 1/50/4
I.) Initially Charged = 24989 v
1.) Source voltage and current

46
EX 806 MODELLING AND SIMULATION LAB
 2.) Active and reactive power

3.) Voltage & Current across Thyristor-1

4.) Voltage & Current across Thyristor-2

47
EX 806 MODELLING AND SIMULATION LAB
5.)Voltage across Capacitor

Step Pulse = 1/50/4

II.) Pre Charged = -0.314 v

1.) Source voltage and current

2.) Active and reactive power

48
EX 806 MODELLING AND SIMULATION LAB
3.) Voltage & Current across Thyristor-1

4.) Voltage & Current across Thyristor-2

49
EX 806 MODELLING AND SIMULATION LAB
5.) Voltage across Capacitor

Step Pulse = 1/50/8

I.) Initially Charged = 24989 v

1.) Source voltage and current

2.) Active and reactive power

50
EX 806 MODELLING AND SIMULATION LAB
3.) Voltage & Current across Thyristor-1

4.) Voltage & Current across Thyristor-2

5.) Voltage across Capacitor

51
EX 806 MODELLING AND SIMULATION LAB
 Step Pulse = 1/50/8

II.) Pre-Charged = -0.314 v

1.) Source voltage and current

2.) Active and reactive power

52
EX 806 MODELLING AND SIMULATION LAB
3. Voltage & Current across Thyristor-1

4.) Voltage & Current across Thyristor-2

5.) Voltage across Capacitor

53
EX 806 MODELLING AND SIMULATION LAB
PROGRAMMING OF TSC

Source Voltage & Current

load visource.mat load iprim.mat

a=vi b=iprim
t=a(1,:) t=b(1,:)
plot (t,a) plot (t,b)

Active & Reactive Power

load active.mat load reactive.mat

c=p d=q
t=c(1,:) t=d(1,:)
plot (t,c) plot (t,d)

Voltage & Current For Thyristor 1

load volts1.mat load curr1.mat

a=vt b=ct
t=a(1,:) t=b(1,:)
plot (t,a) plot (t,b)

Voltage & Current For Thyristor 2

load volts2.mat load curr2.mat

c=vt d=ct
t=c(1,:) t=d(1,:)
plot (t,c) plot (t,d)

Voltage Across Capacitor

Load cvolts.mat
x=vc
t=x(1,:)
plot (t,x)

54
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -7

Aim: To develop the simulation model of a Boost Power Factor Corrector and
evaluate its performance.
SOFTWARE REQUIRED: MATLAB 2013, SIMULINK Library.
THEORY: Researchers are giving attention to the quality of the currents absorbed from the utility
line by electronic equipment, especially harmonic content and power factor. In fact, a low power
factor reduces the power available from the utility grid, while a high harmonic line current distortion
causes EMI problems and cross-interferences. From this point of view the standard rectifier
comprising a diode bridge with a filter capacitor gives unacceptable performances. Thus, many
efforts are being done to develop interface systems, which improve the power factor of standard
electronic loads and it have to maintain the limits recommended by various standards. Hence
converters placed in the system does not only have the task of producing the regulated DC voltage;
but also have to perform the task of power conditioning to limit the harmonics in the system. An
ideal power factor corrector (PFC) should maintain good (unity) power factor on the supply side
while maintaining a fairly regulated output voltage.
For the case of sinusoidal line voltage, the converter must draw a sinusoidal current from the
utility; for this , a suitable sinusoidal reference is generally needed with the control objective is to
force the input current to follow, this reference current, as close as possible. A diode rectifier affects
the ac/dc conversion, while the controller operates the switch in such a way to properly shape the
input current according to its reference. The output capacitor absorbs the input power pulsation,
leaving a small ripple of the output voltage Vo.
The most popular topology in PFC applications is the boost topology, Boost converter
topology generate DC voltage greater than the input voltage. The input current in these converters
have to flow through the inductor hence can easily be actively wave shaped with appropriate current
control mode. Moreover the boost converters provide regulated DC output voltageat unity input
power factor and reduced THD at input ac current. Study on various topologies has been carried out;
however the general boost converter topology is still the widely accepted topology.

REVIEW OF BRIDGELESS BOOST PFC CONVERTERS

Five different type of Boost PFC topologies are discussed in this section . The basic one in
Fig. 6.1(b) called Dual Boost PFC, which have higher efficiency than conventional Boost PFC in
Fig. 6.1(a), because of the reduced semiconductor numbers in line current path, however, this PFC
rectifier has significantly larger CM noise than the conventional Boost PFC. The reason is that: in
the conventional boost PFC, the output ground is always connected to the ac source through full-
bridge rectifier, whereas, in the Dual Boost PFC, the output ground is connected to the ac source
only during positive half cycle through the body diode of switches. So large pulse current from high
frequency switches will flow through capacitor and brings EMI problems

55
EX 806 MODELLING AND SIMULATION LAB
Fig. 7.1(a) Conventional boost converter

(b)Symmetrical semiboost converter

(c) Asymmetrical semiboost converter

(d) Half Bridge converter

(e) VSC converter

The conventional boost topology is the most efficient for PFC applications. This approach is good
for a low to medium power range. It uses a diode bridge to rectify the AC input voltage to DC, which
is then followed by the boost section. As the power level increases, the diode bridge begins to become

56
EX 806 MODELLING AND SIMULATION LAB
an important part of the application and it is necessary for the designer to deal with the problem of
how to dissipate the heat in limited surface area, from the efficiency point of view.
The bridgeless configuration topology presented in this paper avoids the need for the rectifier input
bridge yet maintains the classic boost topology. This is easily done by making use of the body diode
connected between drain and source of Mosfet switches. The circuit shown from a functional point
of view is similar to the common boost converter.
In the traditional topology current flows through two of the bridge diodes in series. In the
bridgeless PFC configuration, current flows through only one diode with the MOSFET providing the
return path. To analyze the circuit operation, it is necessary to separate it into two sections. When
terminal PH1 is high the first section ( M1-D1) operates as the boost stage and the second section
(body diode of M2) operates as the return path for the AC input signal. Figure 6.3(a),(b) shows the
functioning of bridgeless PFC when terminal PH1 is high. Second section will be functioning when
terminal PH2 is high.

Fig. 7.2 Schematic Arrangement of Bridgeless Boost PFC

57
EX 806 MODELLING AND SIMULATION LAB
Fig 7.3(a) M1 Conduction Mode

(b) M1 open Mode

PFC Slow Fast Mos

Conduction Path ON/OFF
Converter Diode diode fet

Conventional 2 slow diode, 1 Mosfet/

4 1 1
PFC ( 2 slow diode, 1 fast diode)

1 body diode , 1 Mosfet /

Bridgeless
0 2 2 ( 1 Mosfet body diode,
PFC
1 diode

Table 7.1: Summary between conventional & Bridgeless boost PFC

58
EX 806 MODELLING AND SIMULATION LAB
Control techniques
Hysteresis control is used to control the Mosfet / switch input signal. Fig.(4) shows this type of
control in which two sinusoidal current references Pref, IV,ref are generated, one for the peak &
other for the valley of the inductor current. According to this control technique, the switch is turned
on when the inductor current goes below the lower reference IV,ref and is turned off when the
inductor current goes above the upper reference IP,ref, giving rise to a variable frequency control.
The switch should be kept open near the zero crossing of the line voltage for avoiding too high
switching frequency.

SIMULINK MODEL:

Fig. 7.4 – (a) Simulink Model (b) Hysteresis control scheme

59
EX 806 MODELLING AND SIMULATION LAB
SIMULINK RESULT:

Steady State Performance of Boost PFC

Simulation results for different topologies viz. supply voltage & current, output voltage & current
with the harmonic spectrum is presented below in different figures. All topologies provide smooth
dc voltage at power factor close to unity and show excellent steady state and dynamic characteristics.
Input current THD is well below the specified limits. There voltage regulation is fairly good for load
variations. More the no. of MOSFETS (less conduction loss), results in higher efficiency, same time
the cost is higher.
Table – 7.2 Analysis of boost PFC

% Power Flow
Time *
Topology Supply PF THD
ms

Conventional 0.99 2.56 Uni directional 30/30

Time* - settling time for input quantity / output quantity

60
EX 806 MODELLING AND SIMULATION LAB
Fig.7.5(a) Simulation model of conventional boost converter
(b ) Supply Voltage and current

Fig. 7.6 Output voltage, Output current, Supply current Harmonic Spectrum of Boost Converter.

61
EX 806 MODELLING AND SIMULATION LAB
CONCLUSION:
Simulation of boost PFC converter is carried out. With the help of inductor; active wave shaping of
current is possible. THD will be reduced with boost-PFC.

62
EX 806 MODELLING AND SIMULATION LAB
 Experiment No. -8

Aim: To develop the simulation model of an Induction Motor Drive fed by a

cascaded Multi-Level Inverter and evaluate its performance

SOFTWARE REQUIRED: MATLAB 2013, SIMULINK Library.

THEORY:

In recent year many industrial drive use ac induction motor because induction motor is less
expensive and reliable generally induction motor is used for constant speed but now a day’s
induction motor is also used for variable speed with the help of power electronics devices. These
electronics devices not only improve the speed of motor but it can also improve the steady and
dynamic characteristics of motor. There are various schemes such as PWM, SPWM, SVPWM,
CPWM. etc. for controlling multilevel inverter like diode clamp inverter, capacitor clamp inverter,
cascading H-bridge multilevel inverter for achieving dynamics performance of induction motor. In
this paper we use cascade H-Bridge multilevel inverter for controlling induction motor.
1) It produce output voltage with low distortion and lower dv/dt .
2) They draw input current with very low distortion.
3) It generates smaller common mode voltage for reducing the stress of the motor load.
4) It can operate with a lower switching frequency.

Inverter topologies:

In recent year industry require higher power which is reached in megawatt. For working with
higher voltage we introduce multi-level inverter to control ac drives. Such as diode clamp inverter,
capacitor clamp inverter and cascaded H-Bridge multilevel inverter. In this paper we briefly discuss
about cascaded H-Bridge multilevel inverter.

II. CASCADE H-BRIDGE MULTILEVEL INVERTER

Cascade H-Bridge multilevel is better than other multi-level inverter because its structure is simple.
It requires less switching components. Cascade H-Bride multilevel inverter is the group of capacitor
and switches.

63
EX 806 MODELLING AND SIMULATION LAB
 Fig. 8.1 Cascading H-Bridge MLI

In the above fig. 8.1. The circuit diagram of cascading H-Bridge multilevel inverter. Cascading H-
Bridge multilevel inverter is most important topology in the multilevel inverter. It gives a desire
AC voltage from several DC input voltage it require less number of component as compare to diode
clamp inverter and flying capacitor inverter each H-Bridge multilevel inverter produce three level
of voltage Vdc, 0, -Vdc by different combination of four switches S1, S2, S3 and S4. then the
magnitude of ac output voltage will be.
V0 = V01+V02+V03+Von ----------------------- (1)
Switching pattern of cascade H-Bridge multilevel inverters shown below.

Table no. 8.1 Switching table for cascade H-Bridge MLI

V0 = S1 S2 S3
Van S4
Vdc 1 0 0 1
0 1 1 0 0
0 0 0 1 1
- Vdc 0 1 1 0

Cascaded N-level inverter:

A cascaded N-Level inverter consist of a number H-Bridge inverter with separate dc source for each
unit and connected in series as shown in fig.2. Each h-Bridge can be produce three level of voltage
namely +Vdc, 0, and -Vdc.

64
EX 806 MODELLING AND SIMULATION LAB
Fig 8.2. Block diagram of cascaded N-Level inverter

For symmetric inverter all dc voltage sources equal to Vdc, the number of available voltage step
level is:
Nstep = 2n +1---------------------- (2)
Where n represented the number of full-bridges and maximum output voltage will be:
Vomax = n×Vdc------------------- (3)

There are following advantage of cascading H-Bridge multilevel inverter:

(1)It reduces total harmonic distortion.
(2)It requires less number of components for each level.
(3)It is more flexible than other multilevel inverter.
(4)Its circuit is simple and reliable.

Disadvantage:
The main disadvantage of cascading H-Bridge multi inverter is it requires separate DC voltage
sources.

III. CONTROL SCHEME FOR MULTILEVEL INVERTER

There are following method for controlling the multilevel inverter discussed below.
(a)Pulse width modulation technique (PWM).
(b)Sinusoidal Pulse width Modulation(SPWM).

65
EX 806 MODELLING AND SIMULATION LAB
(C)Third harmonics pulse width modulation (THI-PWM).
(d)Space vector pulse width modulation (SPPWM)
(e)Selective Harmonic Elimination Method(SHE-PWM).

Pulse width modulation control: -

This method is most popular method of controlling the output voltage, in this method a fixed dc
input voltage is given is given to the inverter and controlled ac output voltage is obtained by
adjusting the off periods of the inverter components.
There are following advantage of pulse width modulation
(1)The output voltage control with this method can be obtained without any additional components.
(2)With this method lower order harmonics can be eliminated or minimized along with its output
voltage control. As higher order harmonics can be filtered easily, the filtering requirements are
minimized.

Space vector pulse width modulation:

In a conventional two level multilevel inverter the harmonics reduction in the output current of
inverter is computed by increasing the switching frequency however in high power applications the
switching frequency of the power device is restricted below 1kHz because of increasing switching
losses and level of dc voltage. While the very high dv/dt which is generated with high DC link
voltage is the cause for electromagnetic interference and motor winding stress. There for from the
harmonic reduction and high DC – link voltage level point of view multilevel inverters are more
suitable.

Multicarrier Sine–PWM :-

Multilevel carrier based PWM method have triangular waves or saw tooth waves multiple carrier
signals show freedom in following characteristics – frequency, amplitude, face of each carrier and
offset between the carriers. The reference wave can be either sinusoidal or trapezoidal. A reference
wave two shows freedom in parameters like frequency, amplitude, phase angle, and injection of
zero sequence signal to it. Hence many multilevel carrier based PWM methods, using these
combinations may be obtained.
The carrier based Schemes can be classified as:
(a)Level shift PWM (LSPWM)
(b)Phase shifted PWM (PSPWM)
(C)Hybrid (H)

66
EX 806 MODELLING AND SIMULATION LAB
SIMULINK MODEL:

Fig.8.6 3-level inverter circuit fed induction motor simulation model.

SIMULINK RESULT:
Fig. 8.7 show the output line to line voltage waveform of three level cascaded H-Bridge multilevel
inverter.
500
Vab(volts)

-500
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6

500
Vbc(volts)

-500
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6

500
Vca(volts)

-500
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6
Time(sec)

Fig.8.7 Three-level cascaded H-Bridge line to line voltage waveform.

67
EX 806 MODELLING AND SIMULATION LAB
Fig. 8.8 show the output line to line voltage waveform of five level cascaded H-Bridge multilevel
inverter.
500
Vab(volts)

-500
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6

500
Vbc(volts)

-500
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6

500
Vca(volts)

-500
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6
Time(sec)

Fig.8.8 Five-level cascaded H-Bridge line to line voltage waveform.

Fig.8.9 Show the rotor speed of induction motor fed by cascaded three level H-Bridge inverter. The
speed will remain constant at 1480 rpm.

2000

1500

1000

500

-500
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

<Electromagnetic torque Te (N*m)>

300
Fig 8.9.Rotor speed of cascaded three level inverter fed induction motor
200
Fig.8.10 Show the rotor speed of induction motor fed by cascaded five-level H-Bridge inverter. The
100
speed will remain constant at 1480 rpm.
0

2000
-100

1500
-200
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
1000 Time

500

-500
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Fig1 8.10. Rotor speed of cascaded five level inverter fed induction motor.

0.5

-0.5 68
EX 806 MODELLING AND SIMULATION LAB
-1
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Time
The % total harmonic distortion of cascaded line inverter voltage is shown in table no.8.2.

Table 8.2 (%THD value)

Level THD
Three level 11.06%
Five level 8.94%

69
EX 806 MODELLING AND SIMULATION LAB
 70
EX 806 MODELLING AND SIMULATION LAB
 71
EX 806 MODELLING AND SIMULATION LAB