Design and Modelling of 5 Phase DFIM for Wind Energy System

DESIGN AND MODELLING OF A 5Ø DOUBLY FED
INDUCTION MACHINE TO IMPROVE THE ENERGY
OUTPUT AND TORQUE IN WIND ENERGY
GENERATOR
A PROJECT REPORT
Submitted by
KRISHNA KUMAR R 412414105036
NAVANEETH M 412414105046
SHACHIN SHIBI R 412414105077
In partial fulfilment for the award of the degree
Of
BACHELOR OF ENGINEERING
In
ELECTRICAL AND ELECTRONICS ENGINEERING
SRI SAI RAM INSTITUTE OF TECHNOLOGY, CHENNAI
ANNA UNIVERSITY: CHENNAI 600 025
APRIL 2018

i
ANNA UNIVERSITY : CHENNAI 600025
BONAFIDE CERTIFICATE
Certified that this project report “DESIGN AND MODELLING OF A 5Ø
DOUBLY FED INDUCTION MACHINE TO IMPROVE ENERGY
OUTPUT AND TORQUE IN WIND ENERGY GENERATOR” is the
bonafide work of
KRISHNA KUMAR R (412414105036)
NAVANEETH M (412414105046)
SHACHIN SHIBI R (412414105077)
who carried out the project work under my supervision.
SIGNATURE SIGNATURE
Mr A. ANABAZHAGAN M.Tech, (Ph.D) Mrs E.MAHESWARI M.E, (Ph.D)
HEAD OF THE DEPARTMENT, SUPERVISOR,
Associate Professor, Associate Professor,
Electrical and Electronics Engineering Electrical and Electronics Engineering
Sri Sai Ram Institute of Technology, Sri Sai Ram Institute of Technology,
West Tambaram, Chennai-44. West Tambaram, Chennai-44.
Submitted for VIVA-VOCE Examination held on __________at Sri Sai Ram
Institute of Technology, West Tambaram, Chennai - 44.
INTERNAL EXAMINER EXTERNAL EXAMINER

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ACKNOWLEDGEMENT
A successful man is one who can lay a firm foundation with the bricks
others have thrown at him.—David Brinkley
Such a successful personality is our beloved founder Chairman, Thiru.
MJF. Ln. LEO MUTHU. At first, we express our sincere gratitude to our
beloved chairman through prayers, who in the form of a guiding star has spread
his wings of external support with immortal blessings.
We express our gratitude to our CEO Mr. J. SAI PRAKASH LEO
MUTHU and our Trustee Mrs. J. SHARMILA RAJAA for their constant
encouragement for completing this project.
We express our sincere thanks to Our beloved principal,
Dr.K.PALANIKUMAR for having given us spontaneous and whole hearted
encouragement for completing this project.
We are indebted to our Head of the Department, Mr.A.ANBAZHAGAN
for his support during the entire course of this project work.
We express our gratitude and sincere thanks to our guide Mrs. E.
MAHESWARI for her valuable suggestions and constant encouragement for
successful completion of this project.
Our sincere thanks to our project coordinator Dr. G. PRAKASH for his
kind support in bringing out this project.
We thank all the teaching and Non-teaching staff members of the
Department of Electrical and Electronics Engineering and all others who
contributed directly or indirectly for the successful completion of the project.

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ABSTRACT
Induction machines are quotidian for both power generation and
electromechanical conversion. Due to the ability to produce useful power at
various rotational velocities, doubly fed induction machines are commissioned
in wind generation units typically along with a step-up transformer. The
contemporary three phase induction generators used in modern wind mills have
a shallow power to cost ratio which makes it unsuitable to meet extended base
loads and peak loads and the torque associated with the machine is also prosaic.
This results in the deficiency of optimization of wind energy generation and adds
to the abomination of renewable modus operandi. The present study proposes a
simulation based analysis on overriding the conventional three phase induction
generators with the five phase counterparts through modelling the aspired gilt-
edge design on a comparative platform as well as delineating a five phase to three
phase converter. The latter is designed with an appropriate scheme to eliminate
the use of the exorbitant step-up transformer and bring about a resilient
performance. The optimal design aggrandizes the energy output, improving the
power to cost ratio for the same geographical area of wind farm and supports up
to an appreciable percentage of peak loads.

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LIST OF CONTENTS
CH.
NO.
TITLE PG.
NO.
ABSTRACT i
LIST OF TABLES vi
LIST OF FIGURES vii
LIST OF SYMBOLS AND ABBREVIATIONS ix
1 INTRODUCTION
1.1 INTRODUCTION TO WIND ENERGY
1.1.1 Wind Turbines
1.1.2 Turbine Components
1.1.3 Types of Wind Turbine Generators
1
2
2
1.2 INTRODUCTION TO DFIM 3
1.3 INTRODUCTION TO CONVERTERS 4
2 LITERATUR REVIEW 6
3 MACHINES IN WIND ENERGY SYSTEM
3.1 GENERAL INTRODUCTION 9
3.2 DC GENERATOR TECHNOLOGIES 9
3.3 AC SYNCHRONOUS GENERATOR TECHNOLOGIES 10
3.3.1 Permanent Magnet Synchronous Generator 11
3.4 AC ASYNCHRONOUS GENERATOR TECHNOLOGIES 12
3.4.1 DOUBLY FED INDUCTION MACHINE 14
3

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4 FIVE PHASE DOUBLY FED INDUCTION MACHINE
4.1 GENERAL INTRODUCTION 17
4.2 COMPARISION OF 1 PHASE, 3 PHASE AND 5 PHASE
INDUCTION MACHINES
18
4.3 BASIC CIRCUIT DIAGRAM OF 5 PHASE DFIM 19
4.4 SIMULATED COMPARISION OF 3 PHASE AND 5
PHASE DFIM
20
5 CONVERTERS
5.1 FIVE PHASE AC – DC CONVERTER 21
5.2 DC – DC BUCK BOOST CONVERTER 23
5.3 DC – THREE PHASE AC CONVERTER 24
5.4 DESIGN PARAMETERS 25
6 PROPOSED SYSTEM
6.1 GENERAL BLOCK DIAGRAM 26
6.2 PRINCIPLE OF OPERATION 26
6.3 HARDWARE LAYOUT 27
7 SIMULATED RESULTS AND DISCUSSION
7.1 SIMULATION CIRCUIT 30
7.1.1 Simulation of Five Phase DFIM 30
7.1.2 Simulation of Converter System 32
7.2 SIMULATION RESULT 34
7.2.1 Torque of Five Phase DFIM 34
7.2.2 Voltage Waveform of Five Phase DFIM 34

iv
7.2.3 Current Waveform of Five Phase DFIM 35
7.2.4 Speed – Time Curve 36
7.2.5 Voltage at DC - Link 36
7.2.6 Voltage at Grid Connection 37
7.2.7 Power Flow to Grid 38
7.3 TOTAL HARMONIC DISTORTION 38
8 HARDWARE COMPONENTS
8.1 MOSFET 40
8.1.1 Construction 41
8.1.2 Operating Principle of a MOSFET 43
8.1.3 N-Channel Power MOSFET 200V, 50A (IRF260) 44
8.2 PIC MICRO CONTROLLER 45
8.2.1 Features of PIC 16F87XA Series Microcontroller
8.3 DRIVER CIRCUIT (OPTOCOUPLER) 47
8.3.1 General Description 45
8.4 POWER SUPPLY 50
8.4.1 Step Down Transformer 50
8.4.2 Diode Bridge Rectifier 51
8.4.3 LM7812/LM7815 52
8.4.4 LM7912/LM7915 52
9 HARDWARE RESULTS
9.1 HARDWARE PROTOTYPE 54

v
9.2 HARDWARE OUTPUT 55
9.2.1 Five Phase Inverter Output 55
9.2.2 DC Link Voltage 56
9.2.3 Single Phase Inverter Output 56
9.3 COMPARISON OF HARDWARE OUTPUT WITH
SIMULATED OUTPUT
57
10 CONCLUSION AND FUTURE SCOPE 58
APPENDICES
APPENDIX 1: PIC MICROCONTROLLER PROGRAMMING 60
APPENDIX 2: MATLAB DESIGN PARAMETERS OF FIVE
PHASE INDUCTION MACHINE
67
APPENDIX 3: PARAMETERS AND OPERATING
CHARACTERSITICS OF MOSFET
68
APPENDIX 4: PARAMETERS AND OPERATING
CHARACTERSITICS OF OPTOCOUPLER
71
APPENDIX 5: ARCHITECTURE AND FEATURES OF PIC
MICROCONTROLLER
73
REFERENCES 78

vi
LIST OF TABLES
TABLE NO CAPTION PAGE
5.1 Hardware Design Parameter 25
7.2 5 Phase Inverter Switching Sequence 33

vii
LIST OF FIGURES
FIGURE NO CAPTION PAGE
1.1 Basic Wind Energy System 1
1.2 Wind Turbine Model 2
1.3 Existing DFIM based Wind Energy System 4
3.1 DC Generator Based Wind Energy System 10
3.2 PMSG Based Wind Energy System 12
3.3 Induction Generator Based Wind Energy System 13
3.4 DFIM Based Wind Energy System 14
3.5 Control Strategy of DFIM based Wind System 15
4.1 Five Phase DFIM 18
4.2 Equivalent Circuit of Induction Machine 19
4.3 Comparison of speed – time curve three phase and
five phase DFIMs
20
5.1 5 Phase – 10 Pulse AC – DC Converter 21
5.2 Voltage and Current Waveforms 22
5.3 DC – DC Busk Boost Converter 23
5.4 DC – 3 Phase AC Converter 24
5.5 Voltage and Current Waveforms 24
6.1 Block Diagram of Proposed System 26
6.2 Hardware Circuit Diagram – I 27
6.3 Hardware Circuit Diagram – II 28
7.1 Simulation of Five Phase DFIM 30
7.2 DFIM Block 31
7.3 State Space Model of DFIM 32
7.4 Converter System of DFIM 32

viii
7.5 Five Phase Inverter 33
7.6 Input Torque Waveform 34
7.7 Voltage Waveform at Stator and Rotor Winding 35
7.8 Current Waveform Through Stator and Rotor
Winding
35
7.9 Speed Time Curve of DFIM 36
7.10 DC – Link Voltage Waveform 36
7.11 Voltage Waveform at Grid 37
7.12 Waveform of Power Flow Grid 38
7.13 THD of Voltage to Grid Waveform 39
8.1 MOSFET 41
8.2 Types of MOSFET 42
8.3 Pin Diagram of PIC16F877A 46
8.4 Pin Diagram of PIC16F873A 47
8.5 Optocoupler 48
8.6 TLP250 Optocoupler 49
8.7 Multi Tapping Step Down Transformer 50
8.8 Diode Bridge Rectifier 51
9.1 Hardware Prototype 54
9.2 Five phase phase-neutral voltage 55
9.3 Five phase line-line voltage 55
9.4 DC-Link Voltage 56
9.5 Single phase inverter voltage (Load Voltage) 56
9.6 Comparison of output waveform 57

ix
LIST OF SYMBOLS AND ABBREVIATIONS
SYMBOL DESCRIPTION
Vds Direct Axis Voltage of Stator
Vqs Quadrature Axis Voltage of Stator
Vxs Rotational X-Axis Voltage of Stator
Vys Rotational Y-Axis Voltage of Stator
V0s Neutral Axis Voltage of Stator
Vdr Direct Axis Voltage of Rotor
Vqr Quadrature Axis Voltage of Rotor
Vxr Rotational X-Axis Voltage of Rotor
Vyr Rotational Y-Axis Voltage of Rotor
V0r Neutral Axis Voltage of Rotor
ids Direct Axis Current of Stator
iqs Quadrature Axis Current of Stator
ixs Rotational X-Axis Current of Stator
iys Rotational Y-Axis Current of Stator
i0s Neutral Axis Current of Stator
idr Direct Axis Current of Rotor
iqr Quadrature Axis Current of Rotor
ixr Rotational X-Axis Current of Rotor
iyr Rotational Y-Axis Current of Rotor
i0r Neutral Axis Current of Rotor
ψds Direct Axis Flux linkage of Stator

x
ψqs Quadrature Axis Flux linkage of Stator
ψxs Rotational X-Axis Flux linkage of Stator
ψys Rotational Y-Axis Flux linkage of Stator
ψ0s Neutral Axis Flux linkage of Stator
ψdr Direct Axis Flux linkage of Rotor
ψqr Quadrature Axis Flux linkage of Rotor
ψxr Rotational X-Axis Flux linkage of Rotor
ψyr Rotational Y-Axis Flux linkage of Rotor
ψ0r Neutral Axis Flux linkage of Rotor
Rs Stator Resistance
Rr Rotor Resistance
Te Electromechanical Torque
Tm Load Torque
n Number of phases
P Number of poles
ωs Synchronous Speed
ωr Rotor Speed
J Moment of Inertia
Vdc1 DC-link voltage, Output DC Voltage of Buck Boost Converter
Vdc2 Input DC Voltage to Buck Boost Converter
Vph_max_stator Stator maximum phase voltage
Vph_max_rotor Rotor maximum phase voltage
Vph_max_grid Grid maximum phase voltage

xi
αstator Stator Side Converter firing angle
αrotor Rotor Side Converter firing angle
αgrid Grid Side Converter firing angle
D Duty Cycle of Buck-Boost Converter
[
𝑑𝜓
𝑑𝑥
]
Matrix of differential flux linkage in state space model
[V] Matrix of Voltage in state space model
[I] Matrix of Current in state space model
[R] Matrix of Resistance in state space model
[L] Matrix of Inductance in state space model
[ψ] Matrix of Flux linkage in state space model
[ω] Matrix of Reference speed in state space model
DFIG Doubly Fed Induction Generator
DTC Direct Torque Control
MW Megawatt
WTG Wind Turbine Generator
AC Alternating Current
DC Direct Current
IGBT Insulted Gate Bipolar Transistor
PMSG Permanent Magnet Synchronous Generator
PM Permanent Magnet
SCIG Squirrel Cage Induction Generator
PWM Pulse Width Modulation

xii
RSC Rotor Side Converter
GSC Grid Side Converter
PLL Phase Locked Loop
THD Total Harmonic Distortions
IGFET Insulated Gate Field Effect Transistor
RISC Reduced Instruction Set Computer
UPS Uninterrupted Power Supply
LED Light Emitting Diode
PIC Peripheral Interrupt Controller
ADC Analog to Digital Converter
SPWM Sinusoidal Pulse Width Modulation

1
CHAPTER 1
INTRODUCTION
1.1 INTRODUCTION TO WIND ENERGY
Wind is a form of solar energy. Winds are caused by the uneven heating
of the atmosphere by the sun, the irregularities of the earth's surface, and rotation
of the earth. Wind flow patterns are modified by the earth's terrain, bodies of
water, and vegetative cover. This wind flow, or motion energy, when "harvested"
by modern wind turbines, can be used to generate electricity.
The terms "wind energy" or "wind power" describe the process by which
the wind is used to generate mechanical power or electricity. Wind turbines
convert the kinetic energy in the wind into mechanical power. This mechanical
power can be used for specific tasks (such as grinding grain or pumping water)
or a generator can convert this mechanical power into electricity to power homes,
businesses, schools, and the like.
Fig 1.1 Basic Wind Energy System

2
1.1.1 Wind Turbines
Wind turbines, like aircraft propeller blades, turn in the moving air and
power an electric generator that supplies an electric current. The wind turns the
blades, which spin a shaft, which connects to a generator and makes electricity.
1.1.2 Turbine Components
Horizontal turbine components include:
 blade or rotor, which converts the energy in the wind to rotational shaft
energy;
 a drive train, usually including a gearbox and a generator;
 a tower that supports the rotor and drive train; and
 other equipment, including controls, electrical cables, ground support
equipment, and interconnection equipment.
Fig 1.2 Wind Turbine Model

3
1.1.3 Types of Wind Turbine Generators
Type 1: It consists of a squirrel cage induction generator connected directly to
the power grid. It is used for a small range of wind speed.
Type 2: It consists of an AC-DC-AC converter in addition to the induction
generator before being connected to the power grid.
Type 3: It consists of a wound rotor induction generator connected directly to the
grid, where the rotors speed is adjusted using a rheostat.
Type 4: It consists of a Double Fed Induction Generator connected directly to the
grid, where the rotor speed is adjusted using back to back converters.
1.2 INTRODUCTION TO DOUBLY FED INDUCTION MACHINE
A Doubly Fed Induction Generator as its name suggests is a 3 phase
induction generator where both the rotor and stator windings are fed with 3 phase
AC signal. It consists of multi-phase windings placed on both the rotor and stator
bodies. It also consists of a multiphase slip ring assembly to transfer power to the
rotor. It is typically used to generate electricity in wind turbine generators.
The principle of the DFIG is that rotor windings are connected to the grid
via slip rings and back-to-back voltage source converter that controls both the
rotor and the grid currents. Thus rotor frequency can freely differ from the grid
frequency (50 or 60 Hz). By using the converter to control the rotor currents, it
is possible to adjust the active and reactive power fed to the grid from the stator
independently of the generator’s turning speed. The control principle used is
either the two-axis current vector control or direct torque control (DTC).

4
Fig1.3 Existing DFIM based Wind Energy System
The doubly-fed generator rotors are typically wound with 2 to 3 times the
number of turns of the stator. This means that the rotor voltages will be higher
and currents respectively lower. Thus in the typical ± 30% operational speed
range around the synchronous speed, the rated current of the converter is
accordingly lower which leads to a lower cost of the converter.
Advantages compared to constant speed turbines:
 Enables variable speed operation for increased kilowatt-hour production
 Uses a small converter, one-third of the nominal power
 Supplies reactive power for grid support
 High total system efficiency
 Is a technical and economical solution for grid code compliance
1.3 INTRODUCTION TO CONVERTERS
In electrical engineering, the term converters generally refer to voltage
converters. These converters are used to convert one form of voltage to another
form. These converters does not bring any change in power. But there might be

5
loss of power due to switching. The impartment of semiconductors in the field
of electrical engineering made the great boom in this field. As a result the power
flow can be controlled by using converters.
In the field of renewable energy, converters play a major role in stabilizing
the power flow from source to grid. Without these converters the concept of
renewable energy would not exist. These converters are basically used to regulate
the voltage due to fluctuations in source and control the reverse flow in power
from grid to source.
The basic power converters used in renewable energy systems are AC –
DC, DC – AC, DC – DC buck boost, AC – DC – AC converters and its
derivatives. All these converters are used to inject the generated power to the
system and to reduce the power oscillations.

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CHAPTER 2
LITERATUR REVIEW
[1] “Introduction to Doubly-Fed Induction Generator for Wind Power
Applications” - Dr John Fletcher and Jin Yang, University of Strathclyde,
Glasgow, UK
This article introduces the operation and control of a Doubly-fed Induction
Generator (DFIG) system. The DFIG is currently the system of choice for multi
MW wind turbines. The aerodynamic system must be capable of operating over
a wide wind speed range in order to achieve optimum aerodynamic efficiency by
tracking the optimum tip-speed ratio. Therefore, the generator’s rotor must be
able to operate at a variable rotational speed. The DFIG system therefore operates
in both sub- and super-synchronous modes with a rotor speed range around the
synchronous speed. This chapter will introduce the basic features and normal
operation of DFIG systems for wind power applications basing the description
on the standard induction generator. Different aspects that will be described
include their variable-speed feature, power converters and their associated
control systems, and application issues.
[2] “Doubly Fed Induction Generator System for Wind Turbines” - S Muller,
M Deicke and Rik W De Doncker
This article shows the need to have adjustable speed generators for wind turbines
when output power becomes higher than 1 MW to have greater efficiency. It also
gives the idea of doubly fed induction generator system presented which offers
many advantages to reduce Cost and has the potential to be built economically at
power levels above 1.5 MW, e.g., for off-shore applications. The simulations

7
show excellent response of the DFIG independent of speed. The measurements
obtained from 1.5MW units currently in operation confirm the theoretical results.
Thus proving that DFIM is an efficient and effective way forward.
[3] “Simulation of Inverter Fed Five Phase Induction Motor” - Palak
G.Sharma, S. Rangari
This paper presents dynamic simulation of inverter fed five phase induction
machine based on mathematical modelling. SPWM Technique is used to
generate the pulses for the inverter. The theory of reference frame has been used
to analyze the performance of five phase induction machine. In this paper
Simulink implementation of induction machine using dqxy0 axis transformation is
used. This paper also provides mathematical formulae and calculation of a Five
Phase Induction machine. Simulation results of the same were provided. Further,
in this paper implementation and dynamic simulation of a five phase induction
motor fed from five level inverter using MATLAB is studied. The model was
tested for 3hp motor, 50Hz.
[4] “Preliminary investigation of an inverter-fed 5-phase induction motor” -
EE Ward, C.Eng and H Harer
The paper reports some preliminary experiments on an inverter-fed 5-phase
induction motor, and shows measured values of instantaneous current and torque.
These are compared with the values predicted by a dual analogue. The amplitude
of the torque fluctuation is approximately one third of that of the corresponding
3-phase motor. In this paper modelling and simulation of five phase induction
motor is been described which is fed from a voltage source inverter.
[5] “Performance Evaluation of Wind Turbine with Doubly-Fed Induction
Generator” - Agus Jamal, Slamet Suripto and Ramadoni Syahputra

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This paper presents the performance evaluation of wind turbine with doubly-fed
induction generator. A stator flux oriented vector control is used for the variable
speed doubly fed induction generator operation. By controlling the generator
excitation current the amplitude of the stator EMF is adjusted equal to the
amplitude of the grid voltage. To set the generator frequency equal to the grid
one, the turbine pitch angle controller accelerates the turbine and generator until
it reaches the synchronous speed. The system is modeled and simulated in the
Simulink software for modeling of all types of induction generator
configurations. The model makes use of rotor reference frame using dynamic
vector approach for machine model. The results of a single line to ground fault
and a symmetrical three-phase ground fault is analyzed. The results show that
the wind energy conversion system can normally operate in fault conditions.
[6] “Generalized d-q Model of n-Phase Induction Motor Drive” - G.
Renukadevi, K. Rajambal
This paper presents a generalized d-q model of n- phase induction motor drive.
Multi -phase (n-phase) induction motor (more than three phases) drives possess
several advantages over conventional three-phase drives, such as reduced
current/phase without increasing voltage/phase, lower torque pulsation, higher
torque density, fault tolerance, stability, high efficiency and lower current ripple.
When the number of phases increases, it is also possible to increase the power in
the same frame. In this paper, a generalized dq-axis model is developed in
MATLAB/Simulink for an n phase induction motor. The simulation results are
presented for 5, 6, 7, 9 and 12 phase induction motor under varying load
conditions. Transient response of the multi-phase induction motors are given for
different number of phases. Fault tolerant feature is also analyzed for 5-phase
induction motor drive.

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CHAPTER 3
MACHINES IN WIND ENERGY SYSTEM
3.1 GENERAL INTRODUCTION
There are three main types of wind turbine generators (WTGs) which can
be considered for the various wind turbine systems, these being direct current
(DC), alternating current (AC) synchronous and AC asynchronous generators. In
principle, each can be run at fixed or variable speed. Due to the fluctuating nature
of wind power, it is advantageous to operate the WTG at variable speed which
reduces the physical stress on the turbine blades and drive train, and which
improves system aerodynamic efficiency and torque transient behaviors.
3.2 DC GENERATOR TECHNOLOGIES
In conventional DC machines, the field is on the stator and the armature is
on the rotor. The stator comprises a number of poles which are excited either by
permanent magnets or by DC field windings. If the machine is electrically
excited, it tends to follow the shunt wound DC generator concept. The DC wind
generator system consists of a wind turbine, a DC generator, an insulated gate
bipolar transistor (IGBT) inverter, a controller, a transformer and a power grid.
For shunt wound DC generators, the field current (and thus magnetic field)
increases with operational speed whilst the actual speed of the wind turbine is
determined by the balance between the WT drive torque and the load torque. The
rotor includes conductors wound on an armature which are connected to a split-
slip ring commentator. Electrical power is extracted through brushes connecting
the commentator which is used to rectify the generated AC power into DC output.

10
Clearly, they require regular maintenance and are relatively costly due to
the use of commutators and brushes. In general, these DC WTGs are unusual in
wind turbine applications except in low power demand situations where the load
is physically close to the wind turbine, in heating applications or in battery
charging.
Fig 3.1 DC Generator based Wind Energy System
3.3 AC SYNCHRONOUS GENERATOR TECHNOLOGIES
AC synchronous WTGs can take constant or DC excitations from either
permanent magnets or electromagnets and are thus termed PM synchronous
generators (PMSGs) and electrically excited synchronous generators (EESGs),
respectively. When the rotor is driven by the wind turbine, a three-phase power
is generated in the stator windings which are connected to the grid through
transformers and power converters. For fixed speed synchronous generators, the
rotor speed must be kept at exactly the synchronous speed. Otherwise
synchronism will be lost.
In theory, the reactive power characteristics of synchronous WTGs can be
easily controlled via the field circuit for electrical excitation. Nevertheless, when

11
using fixed speed synchronous generators, random wind speed fluctuations and
periodic disturbances caused by tower-shading effects and natural resonances of
components would be passed onto the power grid. Furthermore, synchronous
WTGs tend to have low damping effect so that they do not allow drive train
transients to be absorbed electrically. As a consequence, they require an
additional damping element (e.g. flexible coupling in the drive train), or the
gearbox assembly mounted on springs and dampers. When they are integrated
into the power grid, synchronizing their frequency to that of the grid calls for a
delicate operation. In addition, they are generally more complex, costly and more
prone to failure than induction generators. In the case of using electromagnets in
synchronous machines, voltage control takes place in the synchronous machine
while in permanent magnet excited machines, voltage control is achieved in the
converter circuit.
3.3.1 PERMANENT MAGNET SYNCHRONOUS GENERATOR
PM generators have been gradually used in wind turbine applications due
to their high power density and low mass. Often these machines are referred to
as the permanent magnet synchronous generators (PMSGs) and are considered
as the machine of choice in small wind turbine generators. The rugged PMs are
installed on the rotor to produce a constant magnetic field and the generated
electricity is taken from the armature (stator) via the use of the commutator,
sliprings or brushes.
The principle of operation of PM generators is similar to that of
synchronous generators except that PM generators can be operated
asynchronously. The advantages of PMSGs include the elimination of
commutator, slip rings and brushes so that the machines are rugged, reliable and

12
simple. The use of PMs removes the field winding (and its associated power
losses) but makes the field control impossible and the cost of PMs can be
prohibitively high for large machines. Because the actual wind speeds are
variable, the PMSGs cannot generate electrical power with fixed frequency. As
a result, they should be connected to the power grid through AC-DC-AC
conversion by power converters. That is, the generated AC power (with variable
frequency and magnitude) is first rectified into fixed DC and then converted back
into AC power (with fixed frequency and magnitude). It is also very attractive to
use these permanent magnet machines for direct drive application.
Obviously, in this case, they can eliminate troublesome gearboxes which
cause the majority of wind turbine failures. The machines should have large pole
numbers and are physically large than a similarly rated geared machine.
Fig 3.2 PMSM based Wind Energy System
3.4 AC ASYNCHRONOUS GENERATOR TECHNOLOGIES
Modern wind power systems use induction machines extensively in wind
turbine applications. These induction generators fall into two types: fixed speed

13
induction generators (FSIGs) with squirrel cage rotors (sometimes called squirrel
cage induction generators-SQIGs) and doubly fed induction generators (DFIGs)
with wound rotors.
When supplied with three-phase AC power to the stator, a rotating
magnetic field is established across the airgap. If the rotor rotates at a speed
different to synchronous speed, a slip is created and the rotor circuit is energized.
Generally speaking, induction machines are simple, reliable, inexpensive and
well developed.
They have high degree of damping and are capable of absorbing rotor
speed fluctuations and drive train transients (i.e. fault tolerant). However,
induction machines draw reactive power from the grid and thus some form of
reactive power compensation is needed such as the use of capacitors or power
converters. For fixed-speed induction generators, the stator is connected to the
grid via a transformer and the rotor is connected to the wind turbine through a
gearbox. The rotor speed is considered to be fixed (in fact, varying within a
narrow range).
Fig 3.3 Induction Generator based Wind Energy System
SCIGs can be utilized in variable speed wind turbines, as in controlling
synchronous machines. However, the output voltage cannot be controlled and
Generator

14
reactive power needs to be supplied externally. Clearly, fixed speed induction
generators are limited to operate only within a very narrow range of discrete
speeds. Other disadvantages of the machines are related to the machine size,
noise, low efficiency and reliability. These machines have proven to cause
tremendous service failures and consequent maintenance.
3.4.1 DOUBLY FED INDUCTION MACHINE
In the DFIG topology, the stator is directly connected to the grid through
transformers and the rotor is connected to the grid through PWM power
converters. The converters can control the rotor circuit current, frequency and
phase angle shifts. Such induction generators are capable of operating at a wide
slip range (typically ±30% of synchronous speed). As a result, they offer many
advantages such as high energy yield, reduction in mechanical stresses and power
fluctuations, and controllability of reactive power. For induction generators, all
the reactive power energizing the magnetic circuits must be supplied by the grid
or local capacitors. Induction generators are prone to voltage instability. When
capacitors are used to compensate power factor, there is a risk of causing self-
excitation.
Fig 3.4 DFIM based Wind Energy System
Generator

15
Additionally, damping effect may give rise to power losses in the rotor.
There is no direct control over the terminal voltage (thus reactive power), nor
sustained fault currents. The rotor of the DFIG is mechanically connected to the
wind turbine through a drive train system, which may contain high and low speed
shafts, bearings and a gearbox. The rotor is fed by the bi-directional voltage-
source converters. Thereby, the speed and torque of the DFIG can be regulated
by controlling the rotor side converter (RSC). Another feature is that DFIGs can
operate both sub-synchronous and super-synchronous conditions. The stator
always transfers power to the grid while the rotor can handle power in both
directions. The latter is due to the fact that the PWM converters are capable of
supplying voltage and current at different phase angles. In sub-synchronous
operation, the rotor-side converter acts as an inverter and the grid-side converter
(GSC) as a rectifier. In this case, active power is flowing from the grid to the
rotor.
Fig 3.5 Control Strategy of DFIM based Wind Energy System

16
Under super-synchronous condition, the RSC operates as a rectifier and
the GSC as an inverter. Consequently, active power is flowing from the stator as
well as the rotor to the power grid.

17
CHAPTER 4
FIVE PHASE DOUBLY FED INDUCTION MACHINE
4.1 GENERAL INTRODUCTION
In the recent era of electrical energy generation, the concept of green
renewable energy has made a greater impact. But the concept of wind energy
generation has started decades before. In 1960’s there was a theoretical analysis
performed and reaches have started in the field of multi-phase induction
machines for wind energy generation. But the complexity, and predominate three
phase systems the research in this field has lagged. But still the reach in
improving the wind energy generation is progress in the field of imparting multi-
phase multi-level converters for converting this multi-phase power to three phase
power.
These multi-phase machines have greater advantages over conventional
three phase machines in-terms of performance, efficiency and life. The basic
multi-phase machine other than 3 phase induction motor is 5 phase induction
motor. The use of this motor is seen an advantage in industries for critical
processes. And extending this to 7 phases. But the major disadvantage of these
multi-phase machines are the constructional complexity and cost of
manufacturing.
The concept of doubly fed is seen in induction machine for faster response
and better performance. The power fed to a single machine from grid is split
between two windings internally so that the machine operates in the region with
better performance and due to internal balance the machine produce lesser
harmonics as it tries to reach a stable position. This is also seen in reverse

18
motoring operation i.e. generation. The net power output from the machine is
stable even in load fluctuations as the load is shared between stator and rotor the
machine. So the power oscillations are damped internally in the link between
stator and rotor.
Fig 4.1 Five Phase DFIM
4.2 COMPARISION OF 1 PHASE, 3 PHASE AND 5 PHASE INDUCTION
MACHINES
In three phase induction machine, the machine has its advantages over all
other multi-phase machines as this is used for common and conventional
purposes. But when it comes to doubly fed machine concept the use of coupling
transformer and AC – DC – AC converter increases the cost. The system
becomes costly in capital investment but efficient in power production.
In five phase induction machine, the machine takes its advantage in doubly
fed operation because of use of AC – DC – AC converter linking the stator and
rotor power through a DC link, making it cost efficient and also there is ease in
conversion from five phase to three phase. Thus use of higher poly phase

19
induction machine in wind energy generation is has more advantages but indeed
with incremental capital cost.
The use of doubly fed concept gets improved when reaching higher phases
and the irregularity in voltages and current due to source and load fluctuations
get internally damped.
4.3 BASIC CIRCUIT DIAGRAM OF 5 PHASE DFIM
The equivalent circuit of five phase induction machine is same as that of
three phase induction machine. This analysis remains the same but the difference
is conversion of normal axis to rotating axis of direct and quadrature magnetic
axis.
Fig 4.2 Equivalent Circuit of Induction Machine
The relation between voltage, current and flux linkage are as,
For Stator side, For Rotor Side,
𝑉𝑑𝑠 = 𝑅 𝑠 𝑖 𝑑𝑠 − 𝜔 𝑎 𝜓 𝑞𝑠 +
𝑑𝜓 𝑑𝑠
𝑑𝑡
𝑉𝑑𝑟 = 𝑅 𝑟 𝑖 𝑑𝑟 − (𝜔 𝑎 − 𝜔)𝜓 𝑞𝑟 +
𝑑𝜓 𝑑𝑟
𝑑𝑡
𝑉𝑞𝑠 = 𝑅 𝑠 𝑖 𝑞𝑠 + 𝜔 𝑎 𝜓 𝑑𝑠 +
𝑑𝜓 𝑞𝑠
𝑑𝑡
𝑉𝑞𝑟 = 𝑅 𝑟 𝑖 𝑞𝑟 + (𝜔 𝑎 − 𝜔)𝜓 𝑑𝑟 +
𝑑𝜓 𝑞𝑟
𝑑𝑡
𝑉𝑥𝑠 = 𝑅 𝑠 𝑖 𝑥𝑠 +
𝑑𝜓 𝑥𝑠
𝑑𝑡
𝑉𝑥𝑟 = 𝑅 𝑟 𝑖 𝑥𝑟 +
𝑑𝜓 𝑥𝑟
𝑑𝑡

20
𝑉𝑦𝑠 = 𝑅 𝑠 𝑖 𝑦𝑠 +
𝑑𝜓 𝑦𝑠
𝑑𝑡
𝑉𝑦𝑟 = 𝑅 𝑟 𝑖 𝑦𝑟 +
𝑑𝜓 𝑦𝑟
𝑑𝑡
𝑉0𝑠 = 𝑅 𝑠 𝑖0𝑠 +
𝑑𝜓0𝑠
𝑑𝑡
𝑉0𝑟 = 𝑅 𝑟 𝑖0𝑟 +
𝑑𝜓0𝑟
𝑑𝑡
The higher multi-phase induction machine produces better torque because
it is directly proportional to number of phases. The torque equation of n-phase
induction machine is given as,
𝑇𝑒 =
𝑛
2
𝑃
2
1
𝜔 𝑠
(𝜓 𝑑𝑠 𝑖 𝑞𝑠 − 𝜓 𝑞𝑠 𝑖 𝑑𝑠) (4.1)
𝜔𝑟 = ∫
𝑃
2𝐽
(𝑇𝑒 − 𝑇 𝑚) (4.2)
4.4 SIMULATED COMPARISION OF 3 PHASE AND 5 PHASE DFIM
For comparing the three phase DFIM with five phase DFIM, we use speed
– time curve generated for an equal input torque. Initially the machine is allowed
start in no load and at 6 second an additional propagating torque is given making
the machine act as generator. From analyzing the graph, we can conclude that
the speed oscillations in reduced in five phase DFIM when compared with three
phase DFIM.
Fig 4.3 Comparison of speed – time curve three phase and five phase
DFIMs

21
CHAPTER 5
CONVERTERS
5.1 FIVE PHASE AC – DC CONVERTER
Five phase AC to DC converter is used to provide a link between five
phase induction machine stator/rotor to dc-link/DC–DC Buck Boost converter
respectively. MOSFET is used as switching device for these converters imparting
high frequency switching by Pulse Width Modulation (PWM). Now-a-days the
use of semicron switches enables flexible and simple control of the converters.
Fig 5.1 Five phase ten pulse AC – DC Converter
The 5-phase 10-pulse converter is used to link the 5-phase AC system to
DC system. The power flow between the systems is controlled by firing angle
(α). The voltage equation of the converter is given by,
𝑉𝑑𝑐1 = 1.87 𝑉𝑝ℎ_max _𝑠𝑡𝑎𝑡𝑜𝑟 cos 𝛼 𝑠𝑡𝑎𝑡𝑜𝑟 (5.1)
𝑉𝑑𝑐2 = 1.87 𝑉𝑝ℎ_max _𝑟𝑜𝑡𝑜𝑟 cos 𝛼 𝑟𝑜𝑡𝑜𝑟 (5.2)

22
The firing angle is controlled by stator side control/rotor side control for
stator/rotor respectively. The voltage and current waveform of converter is
shown in figure 5.2.
Fig 5.2 Voltage and current of five phase ten pulse AC – DC Converter

23
5.2 DC – DC BUCK BOOST CONVERTER
Two different topologies are called buck–boost converter. Both of them
can produce an output voltage much larger (in absolute magnitude) than the input
voltage. Both of them can produce a wide range of output voltage from that
maximum output voltage to almost zero.
Fig 5.3 DC – DC Buck Boost Converter
A buck (step-down) converter followed by a boost (step-up) converter –
The output voltage is of the same polarity as the input, and can be lower or higher
than the input. Such a non-inverting buck-boost converter may use a single
inductor that is used as both the buck inductor and the boost inductor The buck–
boost converter is a type of DC-DC converter that has an output voltage
magnitude that is either greater than or less than the input voltage magnitude. It
is a switch mode power supply with a similar circuit topology to the boost
converter and the buck converter. The output voltage is adjustable based on the
duty cycle of the switching transistor.
The voltage equation is given as,
For Buck mode, (Vdc1> Vdc2)
𝑉 𝑑𝑐2
𝑉 𝑑𝑐1
= 𝐷 (5.3)
For Boost mode, (Vdc2> Vdc1)
𝑉 𝑑𝑐2
𝑉 𝑑𝑐1
= 1 − 𝐷 (5.4)

24
5.3 DC – THREE PHASE AC CONVERTER
DC to three phase AC converter is used to provide a link between dc-link
and grid. MOSFET is used as switching device for these converters imparting
high frequency switching by Pulse Width Modulation (PWM).
Fig 5.4 DC – Three Phase AC Converter
This converter is controlled by grid side controller. In this control strategy,
the frequency of grid is sensed by PLL circuit and used to generate the gate pulse
according to frequency and synchronized with the grid.
𝑉𝑑𝑐1 = 1.653 𝑉𝑝ℎ_max _𝑔𝑟𝑖𝑑 cos 𝛼 𝑔𝑟𝑖𝑑 (5.5)
Fig 5.5 Voltage and Current waveforms of DC – Three Phase AC
Converter

25
5.4 DESIGN PARAMETERS
Table 5.1 Hardware Design Parameters
S.No. Parameters Specifications
1. 5 phase Source 15V
2. LC filter 10 mH & 20 μF
3. Load Resistance 1Ω
4. MOSFET FET ON Resistance : 0.1 Ohm
5. Microcontroller PIC16F877A, PIC16F873A

26
CHAPTER 6
PROPOSED SYSTEM
6.1 GENERAL BLOCK DIAGRAM
Fig 6.1 Block Diagram of Proposed System
6.2 PRINCIPLE OF OPERATION
The five phase DFIM initially draws power during the initial phase from
the grid to start the turbine. As the inertia of the turbine breaks, then power is
generated from the DFIM and fed in to the grid. The control of five phase AC –
DC converter and DC – DC converter is controlled based on the speed of the
DFIM and bus voltage. The DC – three phase AC converter is controlled by
frequency of grid, voltage at grid. The power gets stabilized in the DFIM by DC-
link between rotor and stator with the help of converter. The filter circuit is used
only at the grid connection point to so that the stability of the power supplied to
the grid is regulated and all other converters produce harmonics get damped in
the internal connection. Thus the power flow is regulated between DFIM and
grid and making it more efficient. The use of five-phase DFIM imparts quicker

27
starting as the torque is higher for multi-phase induction machine and rational
power flow between the stator and rotor.
6.3 HARDWARE LAYOUT
The figure shows the hardware block diagram.
Fig 6.2 Hardware Circuit Diagram – I

28
Fig 6.3 Hardware Circuit Diagram – II
The hardware circuit consists of two separate layouts, one to act as the
source and the other to perform the function of conversion and control. The input
supply of 5 phase is given by converting a 1 phase AC supply into a 5 Phase
supply using a diode bridge rectifier and a 5 phase inverter circuits. This is layout
is controlled by PIC16F877A. The inverter is driven by IRF260 optocoupler. The
power to the driver circuit is given by six regulated power supplies. Five
regulated supplies are used to dive the upper leg of 5 phase inverter. One driver

29
circuit is used to drive all lower legs of inverter. The output of the 5 phase inverter
in given as supply to the 5 phase diode bridge rectifier converter of stator and
rotor. In order to bring a varying drop in the rotor voltage, a split capacitor is
added in the circuit such that the rotor voltage is varied about 50% of the stator
voltage. The control circuit consisting of PIC16F873A gives the PWM input for
triggering the MOSFET switches of DC-DC buck – boost converter and single
phase inverter. The rotor side 5 phase converter output is then given as input to
a buck – boost converter, which boosts the rotor voltage to that of the stator
voltage. Then both the stator and rotor voltages are combined. Then the
combined output is fed to single phase inverter to generate single phase square
wave as output. This is converter to sinusoidal output by adding a LC filter. The
MOSFET switches is driven by IRF260 optocoupler. The driver is supplied by
three separate regulated voltage supply for inverter and one for DC-DC Buck –
Boost converter.

30
CHAPTER 7
SIMULATED RESULTS AND DISCUSSION
7.1 SIMULATION CIRCUIT
7.1.1 SIMULATION OF FIVE PHASE DFIM
The following diagram shows the MATLAB Simulink model of a typical
five phase DFIM, through which the voltage and current of the machine were
measured. From the Fig 7.1, it is clear that five single phase sources are fed into
the machine subsystem with the necessary phase angle of 72o
.
Fig 7.1 Simulation of five phase DFIM
The following MATLAB Simulink model shows the Simulink library
standard implicit design of normal induction machine. Initially the volatge is
sensed and Vabcde is converter to Vdqxy0 and fed to state space model of induction

31
motor. The output of model is the current as Idqxy0 which is converter to Iabcde
by inverse conversion. This value is fed to current source. The mechanical model
is constructed based on integration of torque to speed then to theta.
Fig 7.2 DFIM Block
The following MATLAB Simulink model shows the state space model of
induction machine. The values are handled as vectors. The voltage vector is
subtracted from flux linkage vector and resistive drop vector. The resistive drop
vector is created by multiplying current vector with resistance vector. The current
vector is created by multiplying flux linkage with inverse inductance vector. The
handled voltage vector is integrated to find the flux linkage vector. This is
equationally represented as
[
𝑑𝜓
𝑑𝑥
] = [𝑉] − [𝜔][𝜓] − [𝐼][𝑅] (7.1)
[𝐼] = [𝐿]−1[𝜓] (7.2)
Based on these two equation the state space model is computed.

32
Fig 7.3 State-space Model of DFIM
7.1.2 SIMULATION OF CONVERTER SYSTEM
The following block depicts the five phase converter circuit of a five phase
DFIM, along with the pulse generator. The system uses normal sinusoidal PWM
technique for gating purpose of the converter.
Fig 7.4 Converter System of DFIM

33
The Fig 7.5 depicts the inverter Simulink Model of the 5 phase machine.
The inverter model consists of 10 MOSFET switches which are triggered using
PWM technique. The switching sequence of the five phase inverter is given in
the following table
Table 7.1 Five Phase Inverter Switching Sequence
MODE
Switches
ON
Terminal
Polarity
9 1,7,8,9,10 A+
B-
C-
D+
E-
10 8,9,101,2 A+
B-C-
D-
E+
1 9,10,1,2,3 A+
B+
C-
D-
E+
2 10,1,2,3,4 A+
B+
C-
D-
E-
3 1,2,3,4,5 A+
B+
C+
D-
E-
4 2,3,4,5,6 A-
B+
C+
D-
E-
5 3,4,5,6,7 A-
B+
C+
D+
E-
6 4,5,6,7,8 A-
B-
C+
D+
E-
7 5,6,7,8,9 A-
B-
C+
D+
E+
8 6,7,8,9,10 A-
B-
C-
D+
E+
Fig 7.5 Five Phase Inverter

34
7.2 SIMULATION RESULT
7.2.1 TORQUE OF FIVE PHASE DFIM
In the Fig 7.6, the torque of the five phase DFIM is shown. From the
simulated graph it is very clear that the machine initially draws current and acts
as a motor, once it attains greater speed it starts acting as generator. This is clear
when the torque shifts to the negative axis. Further, the magnitude of the
generator torque is very high, indicating that the machine is a high torque
machine which is very suitable for wind energy system.
Fig 7.6 Input Torque Waveform
7.2.2 VOLTAGE WAVEFORM OF FIVE PHASE DFIM
The following Fig 7.7, depicts the voltage waveform of the stator and rotor
of a 5 phase DFIM. The simulation results prove that the machine produces a
stable sinusoidal waveform. It is also clear that the rotor voltage is approximately
20% of the stator voltage, thus proving the theoretical explanation of a DFIM.

35
Fig 7.7 Voltage Waveform at Stator and Rotor Winding
7.2.3 CURRENT WAVEFORM OF FIVE PHASE DFIM
The Fig 7.8, shows the current waveform of the stator and rotor of a 5 phase
DFIM.
Fig 7.8 Current Waveform through Stator and Rotor winding

36
7.2.4 SPEED-TIME CURVE
Fig 7.9 Speed Time curve of DFIM
7.2.5 VOLTAGE AT DC–LINK
Fig 7.10 DC – Link Voltage Waveform

37
The Fig 7.10, shows the DC voltage at the DC link capacitor after the
combining the stator voltage with the boosted rotor voltage. It is clear that though
the harmonics are very high, the average DC voltage is constant.
7.2.6 VOLTAGE AT GRID CONNECTION
The Fig 7.11, shows the output voltage of the 3 phase converter. That is,
after the DC output of the stator and rotor are combined and converted into 3
phase AC output, which is to be fed into the grid. The first graph depicts the
actual output voltage with high level of THD. However, when a LC filter is
added, the harmonics are reduced giving a constant 3 phase sinusoidal output,
which can be synchronized with the grid.
Fig 7.11 Voltage Waveform at Grid

38
7.2.7 POWER FLOW TO GRID
The Fig 7.12, shows the power flow from the system to the grid that is the
output power flow from the 3 phase converter to the power grid. It can be
concluded that the output power is constant even with the variation in the input
to the system. Thus, it proves our hypothesis that using a 5 phase DFIM, gives a
fairly constant output power even though there is variation in the wind energy.
Hence making the system more effective and efficient.
Fig 7.12 Waveform of Power Flow Grid
7.3 TOTAL HARMONIC DISTORTION
The total harmonic distortion (THD) is a measurement of the harmonic
distortion present in a Signal and is defined as the ratio of the sum of the powers
of all harmonic components to the power of the fundamental
frequency. Distortion factor, a closely related term, is sometimes used as a

39
synonym. In power systems, lower THD means reduction in peak currents,
heating, emissions, and core loss in motors.
Fig 7.13 THD of voltage to grid waveform

40
CHAPTER 8
HARDWARE COMPONENTS
8.1 MOSFET
The metal-oxide-semiconductor field-effect transistor (MOSFET, MOS-
FET, or MOS FET) is a type of field-effect transistor (FET), most commonly
fabricated by the controlled oxidation of silicon. It has an insulated gate, whose
voltage determines the conductivity of the device. This ability to change
conductivity with the amount of applied voltage can be used for amplifying or
switching electronic signals. A metal-insulator-semiconductor field-effect
transistor or MISFET is a term almost synonymous with MOSFET. Another
synonym is IGFET for insulated-gate field-effect transistor.
The main advantage of a MOSFET is that it requires almost no input
current to control the load current, when compared with bipolar transistors. In an
enhancement mode MOSFET, voltage applied to the gate terminal increases the
conductivity of the device. In depletion mode transistors, voltage applied at the
gate reduces the conductivity.
The "metal" in the name MOSFET is now often a misnomer because the
gate material is often a layer of polysilicon (polycrystalline silicon). Similarly,
"oxide" in the name can also be a misnomer, as different dielectric materials are
used with the aim of obtaining strong channels with smaller applied voltages.
The MOSFET is by far the most common transistor in digital circuits, as
hundreds of thousands or millions of them may be included in a memory chip or
microprocessor. Since MOSFETs can be made with either p-type or n-type

41
semiconductors, complementary pairs of MOS transistors can be used to make
switching circuits with very low power consumption, in the form of CMOS logic.
8.1.1 CONSTRUCTION
Usually the semiconductor of choice is silicon, processed using local
oxidation methods (LOCOS). Recently, some chip manufacturers, most notably
IBM and Intel, have started using a chemical compound of silicon and
germanium (SiGe) in MOSFET channels. Unfortunately, many semiconductors
with better electrical properties than silicon, such as gallium arsenide, do not
form good semiconductor-to-insulator interfaces, and thus are not suitable for
MOSFETs. Research continues on creating insulators with acceptable electrical
characteristics on other semiconductor materials.
To overcome the increase in power consumption due to gate current
leakage, a high-κ dielectric is used instead of silicon dioxide for the gate
insulator, while polysilicon is replaced by metal gates.
Fig 8.1 MOSFET

42
The gate is separated from the channel by a thin insulating layer,
traditionally of silicon dioxide and later of silicon oxynitride. Some companies
have started to introduce a high-κ dielectric and metal gate combination in the 45
nanometer node.
When a voltage is applied between the gate and body terminals, the electric
field generated penetrates through the oxide and creates an inversion layer or
channel at the semiconductor-insulator interface. The inversion layer provides a
channel through which current can pass between source and drain terminals.
Varying the voltage between the gate and body modulates the conductivity of
this layer and thereby controls the current flow between drain and source. This
is known as enhancement mode.
Fig 8.2 shows the circuit symbol of these four types of MOSFETs along
with their drain current vs gate-source voltage characteristics (transfer
characteristics).
Fig 8.2 Types of MOSFET

43
8.1.2 OPERATING PRINCIPLE OF A MOSFET
At first glance it would appear that there is no path for any current to flow
between the source and the drain terminals since at least one of the p n junctions
(source – body and body-Drain) will be reverse biased for either polarity of the
applied voltage between the source and the drain. There is no possibility of
current injection from the gate terminal either since the gate oxide is a very good
insulator. However, application of a positive voltage at the gate terminal with
respect to the source will convert the silicon surface beneath the gate oxide into
an n type layer or “channel”, thus connecting the Source to the Drain as explained
next.
The gate region of a MOSFET which is composed of the gate
metallization, the gate (silicon) oxide layer and the p-body silicon forms a high
quality capacitor. When a small voltage is application to this capacitor structure
with gate terminal positive with respect to the source (note that body and source
are shorted) a depletion region forms at the interface between the SiO2
and the
silicon
As VGS
increases further the density of free electrons at the interface
becomes equal to the free hole density in the bulk of the body region beyond the
depletion layer. The layer of free electrons at the interface is called the inversion
layer and is shown in Fig 8.2 (c). The inversion layer has all the properties of an
n type semiconductor and is a conductive path or “channel” between the drain
and the source which permits flow of current between the drain and the source.
Since current conduction in this device takes place through an n- type “channel”
created by the electric field due to gate source voltage it is called “Enhancement
type n-channel MOSFET”.

44
The value of VGS
at which the inversion layer is considered to have formed
is called the “Gate – Source threshold voltage VGS
(Th)”. As VGS
is increased
beyond VGS
(th) the inversion layer gets somewhat thicker and more conductive,
since the density of free electrons increases further with increase in VGS
. The
inversion layer screens the depletion layer adjacent to it from increasing VGS
. The
depletion layer thickness now remains constant.
8.1.3 N-CHANNEL POWER MOSFET 200V, 50A (IRF260)
The Nell IRF260 is a three-terminal silicon device with current conduction
capability of 50A, fast switching speed, low on-state resistance, breakdown
voltage rating of 200V, and max threshold voltage of 4 volts.
They are designed for use in applications such as switched mode power
supplies, DC to DC converters, motor control circuits, UPS and general purpose
switching applications.
Features:
 RDS(ON) = 0.055Ω @ VGS = 10V
 Ultra low gate charge (230nC max)
 Low reverse transfer capacitance (CRSS = 310pF typical)
 Fast switching capability
 100% avalanche energy specified
 Improved dv/dt capability
 150°C operation temperature

45
8.2 PIC MICRO CONTROLLER
The name PIC initially referred to Peripheral Interface Controller, then it
was corrected as Programmable Intelligent Computer. Early models of PIC had
read-only memory or field-programmable EPROM for program storage, some
with provision for erasing memory. All current models use flash memory for
program storage, and newer models allow the PIC to reprogram itself. Program
memory and data memory are separated. Data memory is 8-bit, 16-bit, and, in
latest models, 32-bit wide. In this project PIC16F87xA series micro controllers
are used for generation of gate pulse.
8.2.1 FEATURES OF PIC 16F87XA SERIES MICRO CONTROLLER
High-Performance RISC CPU:
 Only 35 single-word instructions to learn
 All single-cycle instructions except for program branches, which are
two-cycle
 Operating speed: DC – 20 MHz clock input DC – 200 ns instruction
cycle
 Up to 8K x 14 words of Flash Program Memory, Up to 368 x 8 bytes
of Data Memory (RAM), Up to 256 x 8 bytes of EEPROM Data
Memory
 Pin out compatible to other 28-pin or 40/44-pin PIC16CXXX and
PIC16FXXX microcontrollers
Peripheral Features:
 Timer0: 8-bit timer/counter with 8-bit prescaler

46
 Timer1: 16-bit timer/counter with prescaler, can be incremented during
Sleep via external crystal/clock
 Timer2: 8-bit timer/counter with 8-bit period register, prescaler and
postscaler
 Two Capture, Compare, PWM modules - Capture is 16-bit, max
resolution is 12.5 ns - Compare is 16-bit, max resolution is 200 ns -
PWM max resolution is 10-bit
CMOS Technology:
 Low-power, high-speed Flash/EEPROM technology
 Fully static design
 Wide operating voltage range (2.0V to 5.5V)
 Commercial and Industrial temperature ranges
 Low-power consumption
Fig 8.3 Pin diagram of PIC16F877A

47
Fig 8.4 Pin diagram of PIC16F873A
8.3 DRIVER CIRCUIT (OPTOCOUPLER)
There are many situations where signals and data need to be transferred
from one subsystem to another within a piece of electronics equipment, or from
one piece of equipment to another, without making a direct ohmic electrical
connection. Often this is because the source and destination are (or may be at
times) at very different voltage levels, like a microprocessor, which is operating
from 5V DC but being used to control a MOSFET that is switching at a higher
voltage. In such situations the link between the two must be an isolated one, to
protect the microprocessor from over voltage damage.
Relays can of course provide this kind of isolation, but even small relays
tend to be fairly bulky compared with ICs and many of today’s other miniature

48
circuit components. Because they’re electro-mechanical, relays are also not as
reliable and only capable of relatively low speed operation. Where small size,
higher speed and greater reliability are important, a much better alternative is to
use an optocoupler. These use a beam of light to transmit the signals or data
across an electrical barrier, and achieve excellent isolation.
Optocouplers typically come in a small 6-pin or 8-pin IC package, but are
essentially a combination of two distinct devices: an optical transmitter, typically
a gallium arsenide LED (light-emitting diode) and an optical receiver such as a
phototransistor or light-triggered DIAC. The two are separated by a transparent
barrier which blocks any electrical current flow between the two, but does allow
the passage of light. The basic idea is shown in Fig 8.5, along with the usual
circuit symbol for an optocoupler. Usually the electrical connections to the LED
section are brought out to the pins on one side of the package and those for the
phototransistor or diac to the other side, to physically separate them as much as
possible. This usually allows optocouplers to withstand voltages of anywhere
between 500V and 7500V between input and output. Optocouplers are
essentially, digital or switching devices, so they’re best for transferring either on-
off control signals or digital data. Analog signals can be transferred by means of
frequency or pulse-width modulation.
Fig 8.5 Optocoupler

49
8.3.1 GENERAL DESCRIPTION
In our project the optocoupler is used in the driver circuit. They are used
to isolate the voltage between the main circuit and microcontroller circuit. The
pulse is provided to the MOSFET switch using a microcontroller circuit; this
circuit produces a waveform of 5V DC. This pulse is supplied to MOSFET
switch which is supplied by 12V AC as the source and destination voltage is
different they have to be isolated, which is done using optocoupler.
Features:
 Input threshold current: 5 mA (max.)
 Supply current (ICC): 11 mA (max.)
 Supply voltage (VCC): 10−35 V
 Output current (IO): ±1.5A (max)
 Switching time (tpLH/tpHL): 1.5 μs (max)
 Isolation voltage: 2500 Vrms (min)
Fig 8.6 TLP250 Optocoupler

50
8.4 POWER SUPPLY
Power supply for the circuits is taken from single phase AC home supply
and converter to required supply using transformers, diode rectifiers and voltage
regulators.
8.4.1 STEP DOWN TRANSFORMER
When AC is applied to the primary winding of the power transformer it
can either be stepped down or up depending on the value of DC needed. In our
circuit the transformer of 230v/0-(12/15)v multi tapping is used to perform the
step down operation where a 230V AC appears as 12V/15V AC across the
secondary winding. One alteration of input causes the top of the transformer to
be positive and the bottom negative. The next alteration will temporarily cause
the reverse. The current rating of the transformer used in our project is 1A. Apart
from stepping down AC voltages, it gives isolation between the power source
and power supply circuitries.
Fig 8.7 Multi tapping step down transformer

51
8.4.2 DIODE BRIDGE RECTIFIER
The ac input from the main supply is stepped down using a 230 /30V step
down transformer. The stepped down AC voltage is converted into dc voltage
using a diode bridge rectifier. The diode bridge rectifier consists of four diodes
arranged in two legs. The diodes are connected to the stepped down AC voltage.
For positive half cycle of the ac voltage, the diodes D1 and D4 are forward biased
(ref fig). For negative half cycles diodes D2 and D3 are forward biased. Thus dc
voltage is produced to provide input supply to the DC-DC Converter.
Fig 8.8 Diode Bridge Rectifier
When the positive half cycle is applied to the diode bridge rectifier, the
diodes D1 and D4 are forward biased. The diodes start conducting and the load
current flows through the positive of the supply, diodeD1, the load, the diode D4
and the negative of the supply. The diode D2 and D3 are reverse biased and do
not conduct.
During the negative half cycle, the diodes D1 and D4 are reverse biased
and they stop conducting. The diodes D2 & D3 are forward biased and they start
conducting. The load current flows in the same direction for both the half cycles.
Thus the ac supply given to diode bridge rectifier is converted into pulsating dc.

52
8.4.3 LM7812/LM7815
LM7812 is a 12 volt voltage regulator used to regulate the voltage supplied
to PIC and other driver circuits. LM7815 is a 15 volt voltage regulator used to
regulate the voltage supplied to power circuit.
LM78xx series of fixed-voltage integrated-circuit voltage regulators is
designed for a wide range of applications. These applications include on-card
regulation for elimination of noise and distribution problems associated with
single-point regulation. Each of these regulators can deliver up to 1.5 A of output
current. The internal current-limiting and thermal-shutdown features of these
regulators essentially make them immune to overload. In addition to use as fixed-
voltage regulators, these devices can be used with external components to obtain
adjustable output voltages and currents, and also can be used as the power-pass
element in precision regulators.
Features:
 3-Terminal Regulators
 Output Current up to 1.5 A
 Internal Thermal-Overload Protection
 High Power-Dissipation Capability
 Internal Short-Circuit Current Limiting
 Output Transistor Safe-Area Compensation
8.4.4 LM7912/LM7915
LM7912 is a –12 volt voltage regulator used to regulate the voltage
supplied to PIC and other driver circuits. LM7915 is a –15 volt voltage regulator
used to regulate the voltage supplied to power circuit.

53
The LM79XX series of 3-terminal regulators is available with fixed output
voltages of –5V, –8V, –12V, and –15V. These devices need only one external
component–a compensation capacitor at the output. The LM79XX series is
packaged in the TO-220 power package and is capable of supplying 1.5A of
output current. These regulators employ internal current limiting safe area
protection and thermal shutdown for protection against virtually all overload
conditions. Low ground pin current of the LM79XX series allows output voltage
to be easily boosted above the preset value with a resistor divider. The low
quiescent current drain of these devices with a specified maximum change with
line and load ensures good regulation in the voltage boosted mode.
Features:
 Thermal, short circuit and safe area protection
 Y High ripple rejection
 Y 1.5A output current
 Y 4% tolerance on preset output voltage

54
CHAPTER 9
HARDWARE RESULTS
9.1 HARDWARE PROTOTYPE
Fig 9.1 Hardware Prototype

55
9.2 HARDWARE OUTPUT
9.2.1 FIVE PHASE INVERTER OUTPUT
Fig 9.2 Five phase phase-neutral voltage
Fig 9.3 Five phase line-line voltage

56
9.2.2 DC LINK VOLTAGE
Fig 9.4 DC-Link Voltage
9.2.3 SINGLE PHASE INVERTER OUTPUT
Fig 9.5 Single phase inverter voltage (Load Voltage)

57
9.3 COMPARISON OF HARDWARE OUTPUT WITH SIMULATED
OUTPUT
The output of hardware is maintained constant at the load point i.e. grid
connection point by the converters. The rotor voltage is varied from 2V-6V (20-
50% of stator voltage) and coupled with stator voltage at DC-link point. Even
though the voltage is varied which is simulated in MATLAB, output of hardware
resembles the same as that of simulated output after coupling it with the desired
filter. Comparing the step output wave with simulated output using image
comparators we achieve a result of 85-95% similar image.
Fig 9.6 Comparison of output waveform

58
CHAPTER 10
CONCLUSION AND FUTURE SCOPE
The wind energy generation system for single phase, three phase and five
phase doubly fed induction machines were simulated and it has been clear that
the system coalesced with a five phase doubly fed induction machine yielded
substantial output power and worthwhile torque compared to the other two
systems and also it is theoretically true that the number of active lines is
proportional to the output power and torque. Although the wind energy
generation systems use other types of machines, DFIM was found to be more
appropriate because of its power protrusion. The basic components of the
existing system were analyzed and discussed in detail along with the control
strategies. Meanwhile the proposed system consists of two five phase ac-dc
converter, dc-dc buck boost converter on the rotor side for bi-directional power
flow control and finally a dc – three phase ac converter. The five phase machine
was modeled by means of MATLAB Simulink and the parameters were set such
that the rotor allows 20% of the total power and the stator 80% of the same. The
converter system is MOSFET based and general PWM gating technique was
used in the simulations. MOSFET was chosen as it requires almost no input
current to control the load current. Coming to the hardware part, the controllers
chosen were the PIC16F873 and PIC16F874 based on program memory
considerations. The hardware system of the project was scaled down to a voltage
level of 12V as input. The conclusive grid integration voltage would be a three
phase waveform (single phase in case of the hardware kit) with the appropriate
frequency which was shown with a resistive load in the hardware kit. The
hardware circuit consists of a rectifier to convert the household supply to DC and

59
invert it to obtain a 5 phase AC waveform which would be used as the input for
the stator and the rotor side converters along with LM7812/7815 and
LM7912/7915 for voltage regulation. It is also to be noted that the starting time
of the wind energy generation is shrunk as the torque requirement is satisfied at
a much lesser time.
FUTURE SCOPE
This proposal can be extended to attain higher efficient output system and
more reduced harmonics by increasing the higher order of n for n-phase DFIM.
As the order of n increases the starting torque produced increases and reduce the
starting time for the system. When comparing old values of n the multiples of
lower order (i.e. 9,15,21,25 …) does not support damping of harmonics and
makes the system unstable. Thereby, higher odd prime values of n provide a
sustainable results for implementing. In today’s practicality scenario,
implementation restricts the value of n between 5, 7 and 11 phase DFIM.

60
APPENDIX 1
PIC MICROCONTROLLER PROGRAMMING
PIC Program (Converter)
#include <16F883.h>
#device ADC=10
#use delay(clock=20000000)
#fuses HS,NOPUT,NOBROWNOUT,PROTECT,NOWDT,MCLR
unsigned long Vin,ref_adc,Vac,Vstator;
unsigned long Vout,Vbat,Iac;
unsigned int16 pwm_on_1=2,pwm_pulse=2,d_count,set_limit;
short dis_flag=0;
short st_flag=0;
float error;
float GP=0,GP_1;
float pwm_count=2;
short sft_start=0;
short reach_flag=0;
#define CHARGE 0
#define DISCHARGE 1
#int_timer0
void nine_pwm()
{
d_count+=1;
if(d_count>=100)
{

61
d_count=0;
dis_flag=1;
}
portb=~portb;
set_timer0(61);//10ms
}
void power_scan()
{
//0.62 - 31
//0.89 - 14.43
// /0.89 - 14.43
set_adc_channel(0);
delay_us(40);
Vin = (read_adc()) * 0.767;
set_adc_channel(1);
delay_us(40);
Vout = (read_adc()) * 0.767;
set_adc_channel(2);
delay_us(40);
Vstator = (read_adc()) * 0.767;
}
void fuzzy_control_charge()
{
if(Vout>=ref_adc)
{

62
error= Vout - ref_adc;
pwm_count= ((error)/20.0) * 0.2;
GP=GP - pwm_count;
pwm_on_1 = GP;
}
else
{
error= ref_adc - Vout;
if(reach_flag==0)
{
if(sft_start)
{
delay_us(50);
}
else
GP=GP + pwm_count;
pwm_on_1 = GP;
}
}
}
void main()
{
short ch_flip=0;

63
trisa=0x3f;
trisb=0xf0;
trisc=0x00;
adc_intial();
pwm_intial();
timer_0_intial();
adc_intial();
lcd_int();
while(true)
{
power_scan();
if(dis_flag)
{
ch_flip=~ch_flip;
dis_flag=0;
lcd_clear();
ref_adc=(Vstator +7);
lcd_write(0x80,0);
printf(lcd_write_string,"RT:%02luV ST:%02luV",Vin/10,Vsta
tor/10);
lcd_write(0xc0,0);
printf(lcd_write_string,"Vconv:%02luV ",(Vout)/10);
}
if(Vin>20)
{

64
fuzzy_control_charge();
set_pwm1_duty(pwm_on_1);
}
}
}
PIC Program (Inverter)
#include <16F887.h>
#use delay(clock=20000000)
#fuses HS,NOWDT,PROTECT,MCLR
unsigned char time_count=0,phase=0;
short cycle=0;
unsigned char n_count=0;
#define TIMER_ON enable_interrupts(int_timer0)
#define TIMER_OFF disable_interrupts(int_timer0)
#define PULSE_OUT portc
#int_timer0
void nine_pwm()
{
n_count+=1;
if(n_count>=11)n_count=1;
// if(cycle==1)
{
switch(n_count)
{

65
case 1: portc = 0x13;portd=0x0c;break;
case 2: portc = 0x03;portd=0x1c;break;
case 3: portc = 0x07;portd=0x18;break;
case 5: portc = 0x0e;portd=0x11;break;
case 6: portc = 0x0c;portd=0x13;break;
case 7: portc = 0x1c;portd=0x03;break;
case 10:portc= 0x11;portd=0x0e;break;
}
}
set_timer0(216);//2ms
}
void main()
{
trisa=0x0f;
trisb=0xf0;
trisc=0x00;
trisd=0x00;
timer_0_intial();
time_count=0;phase=0;cycle=0;
time_count=0;phase=0;cycle=0;
TIMER_ON;
n_count=0;

67
APPENDIX 2
MATLAB DESIGN PARAMETERS OF FIVE PHASE INDUCTION
MACHINE
Machine Parameters (Simulation):
Table A2.1 Machine Parameters (Simulation)
Parameter Value
Stator Voltage 575 V
Rotor Voltage 115 V
Poles 4
Base Frequency 50 Hz
Stator Resistance 0.5968 Ω
Rotor Resistance 0.6258 Ω
Stator Inductance 0.0003495 H
Rotor Inductance 0.005473 H
Mutual Inductance 0.0354 H
Moment of Inertia 0.005 kg-m2
/kW
Frictional Factor 0.005879

68
APPENDIX 3
PARAMETERS AND OPERATING CHARACTERSITICS OF MOSFET
SYMB
OL
PARAMETER MIN. TYP. MAX. UNIT
Rth(j-c) Thermal resistance, junction to case 0.45
ºC/W
Rth(c-s) Thermal resistance, case to heat sink 0.24
Rth(j-a) Thermal resistance, junction to ambient 40
Table A3.2 Electrical Characteristics
SYMBOL
PARA
METE
R
TEST CONDITIONS
MI
N.
TYP.
MA
X.
UNI
T
STATIC
V(BR)DSS Drain to source breakdown voltage ID = 250μA, VGS = 0V 200 V
V(BR)DSS/ TJ Breakdown voltage temperature coefficient ID = 1mA, VDS =VGS 0.24 V/ºC
IDS
S
Drain to source leakage current
VDS=200V, VGS=0V TC = 25°C 25.0
μA
VDS=160V, VGS=0V TC=125°C 250
IGS
S
Gate to source forward leakage current VGS = 20V, VDS = 0V 100
nA
Gate to source reverse leakage current VGS = -20V, VDS = 0V -100
RDS(ON) Static drain to source on-state resistance ID = 28A, VGS = 10V
0.05
5
Ω
VGS(TH) Gate threshold voltage VGS=VDS, ID=250μA 2.0 4.0 V
Gfs Forward transconductance VDS = 50V, lD = 28A 24 S
DYNAMIC
CIS
S
Input capacitance
VDS = 25V, VGS = 0V, f =1MHz
5200
pF
CO
SS
Output capacitance 1200
CR
SS
Reverse transfer capacitance 310
td(
ON)
Turn-on delay time
VDD = 100V, VGS = 10V
ID = 50A, RG = 4.3Ω, RD = 2.1Ω
(Note1,2)
23
ns
Tr Rise time 120
td(OFF) Turn-off delay time 100
Tf Fall time 94
QG Total gate charge
VDD = 160V, VGS =
10V ID = 50A,
(Note1,2)
230
nC
QG
S
Gate to source charge 42
QG
D
Gate to drain charge (Miller charge) 110
LD Internal drain inductance
Between lead, 6mm(0.25”) form
package and center of die contact
5
nHLS Internal source inductance 13
Table A3.1 Thermal Resistance

69
SOURCE TO DRAIN DIODE RATINGS AND CHARACTERISTICS (TC = 25°C unless otherwise
specified)
SYMB
OL
PAR
AME
TER
TEST CONDITIONS MIN. TYP. MAX. UNIT
VSD Diode forward voltage ISD = 50A, VGS = 0V 1.8 V
Is (IsD) Continuous source to drain current
Integral reverse P-N junction
diode in the MOSFET
50
A
ISM Pulsed source current 200
Trr Reverse recovery time
ISD = 50A, VGS = 0V,
dIF/dt = 100A/µs
390 590 ns
Qrr Reverse recovery charge 4.8 7.2 μC
Table A3.3 Diode Rating and Characteristics

70
Fig A3.1 Characteristics of MOSFET

71
APPENDIX 4
PARAMETERS AND OPERATING CHARACTERSITICS OF
OPTOCOUPLER
Table A4.1 Electrical Characteristics (Ta = -20~70°C, unless specified)
Characteristic Symbol
Tes
t
Cir
cuit
Test Condition Min. Typ.* Max. Unit
Input forward voltage VF ― IF = 10 mA , Ta = 25°C 1.6 1.8 V
Temperature coefficient
of forward voltage
∆VF /
∆Ta
― IF = 10 mA ― -2.0 ― mV / °C
Input reverse current IR ― VR = 5V, Ta = 25°C ― 10 μA
Input capacitance CT ― V = 0 , f = 1MHz , Ta = 25°C ― 45 250 pF
Output current
“H”
level
IOPH 3
VCC =
30V (*1)
IF = 10
mA V8-6
= 4V
-0.5 -1.5 ―
A
“L”
level
IOPL 2
IF = 0
V6-5 = 2.5V
0.5 2 ―
Output voltage
“H”
level
VOH 4
VCC1 = +15V, VEE1 = -
15V RL = 200Ω, IF = 5mA 11 12.8 ―
V
“L”
level
VOL 5
VCC1 = +15V, VEE1 = -
15V RL = 200Ω, VF =
0.8V
― -14.2 -12.5
Supply current
“H” level ICCH ―
VCC = 30V, IF =
10mA Ta = 25°C
― 7 ―
mAVCC = 30V, IF = 10mA ― ― 11
“L” level ICCL ―
VCC = 30V, IF =
0mA Ta = 25°C 7.5
VCC = 30V, IF = 0mA ― ― 11
Threshold
input current
“Output
L→H”
IFLH ―
VCC1 = +15V, VEE1 = -
15V RL = 200Ω, VO > 0V
― 1.2 5 mA
Threshold
input voltage
“Output
H→L”
IFHL ―
VCC1 = +15V, VEE1 = -
15V RL = 200Ω, VO < 0V
0.8 ― ― V
Supply voltage VCC ― 10 ― 35 V
Capacitanc
e
put)
CS ―
VS = 0 , f = 1MHz
Ta = 25℃
― 1.0 2.0 pF
RS ―
VS = 500V , Ta =
25°C R.H.≤ 60%
1×10
12
10
14
― Ω

72
Table A4.2 Switching Characteristics (Ta = -20~70°C , unless specified)
Characteristic Symbol
Tes
t
Cir
cui
t
Test Condition Min. Typ.* Max. Unit
Propagatio
n delay
time
L→H tpLH
6
IF = 8mA (Note 7)
VCC1 = +15V, VEE1 =
L = 200Ω
― 0.15 0.5
µs
H→L tpHL ― 0.15 0.5
Output rise time tr ― ― ―
Output fall time tf ― ― ―
Common mode
transient immunity at
high level output
CMH 7
VCM = 600V, IF =
8mA VCC = 30V, Ta
= 25°C
-5000 ― ― V / µs
Common mode
transient immunity at
low level output
CML 7
VCM = 600V, IF =
0mA VCC = 30V, Ta
= 25°C
5000 ― ― V / µs
Fig A4.1 Characteristics of TLP250

73
APPENDIX 5
ARCHITECTURE AND FEATURES OF PIC MICROCONTROLLER
Fig A5.1 Architecture of PIC16F883

74
Fig A5.2 Architecture of PIC16F887

75
TIMER0 OPERATION
The Timer0 module is an 8-bit timer/counter with the following features:
 8-bit timer/counter register (TMR0)
 8-bit prescaler (shared with Watchdog Timer)
 Programmable internal or external clock source
 Programmable external clock edge selection
 Interrupt on overflow
8-bit timer mode:
When used as a timer, the Timer0 module will increment every instruction
cycle (without prescaler). Timer mode is selected by clearing the T0CS bit of the
OPTION register to ‘0’. When TMR0 is written, the increment is inhibited for
two instruction cycles immediately following the write.
Fig A5.3 Timer 0 Module

76
ANALOG-TO-DIGITAL CONVERTER (ADC) MODULE
The Analog-to-Digital Converter (ADC) allows conversion of an analog
input signal to a 10-bit binary representation of that signal. This device uses
analog inputs, which are multiplexed into a single sample and hold circuit. The
output of the sample and hold is connected to the input of the converter. The
converter generates a 10-bit binary result via successive approximation and
stores the conversion result into the ADC result registers (ADRESL and
ADRESH). The ADC voltage reference is software selectable to be either
internally generated or externally supplied. The ADC can generate an interrupt
upon completion of a conversion. This interrupt can be used to wake-up the
device from Sleep.
Fig A5.4 ADC Module

77
PWM (Enhanced Mode)
The Enhanced PWM Mode can generate a PWM signal on up to four different
output pins with up to 10-bits of resolution. It can do this through four different
PWM output modes:
 Single PWM
 Half-Bridge PWM
 Full-Bridge PWM, Forward mode
 Full-Bridge PWM, Reverse mode
To select an Enhanced PWM mode, the P1M bits of the CCP1CON register
must be set appropriately. The PWM outputs are multiplexed with I/O pins and
are designated P1A, P1B, P1C and P1D. The polarity of the PWM pins is
configurable and is selected by setting the CCP1M bits in the CCP1CON register
appropriately.
Fig A5.5 PWM Module

78
REFERENCES
1. “Documentation,” Model the dynamics of three-phase asynchronous
machine, also known as induction machine - Simulink. [Online].
Available:
https://in.mathworks.com/help/physmod/sps/powersys/ref/asynchronous
machine.html.
2. “Documentation,” Model the dynamics of three-phase asynchronous
machine, also known as induction machine - Simulink. [Online].
Available:
https://in.mathworks.com/help/physmod/sps/powersys/ref/asynchronous
machine.html.
3. “Doubly-fed generators,” Generators for wind turbines (Generators) |
ABB. [Online]. Available: http://new.abb.com/motors-
generators/generators/generators-for-wind-turbines/doubly-fed-
generators.
4. “Simscape™ User's Guide”, The MathWorks, Inc., 3 Apple Hill Drive,
Natick,MA
5. “Simulink® User's Guide”, The MathWorks, Inc., 3 Apple Hill Drive,
Natick, MA
6. B. Wu, Y. Lang, N. Zargari, S. Kouro, “Power Conversion and Control of
Wind Energy Systems”, Hoboken, NJ, USA:Wiley, 2011.

79
7. F. Blaabjerg and K. Ma, "Wind Energy Systems," in Proceedings of the
IEEE, vol. 105, no. 11, pp. 2116-2131, Nov. 2017.
8. M Stiebler, “Wind Energy Systems for Electric Power Generation”,
Berlin, Heidelberg, Springer, ISBN 978-3-540-68765-8, Aug 2008.
9. Nicholas W. Miller, Juan J. Sanchez-Gasca, William W. Price, Robert W.
Delmerico, “Dynamic Modeling of GE 1.5 and 3.6 MW Wind Turbine-
Generators for Stability Simulations”, GE Power Systems Energy
Consulting, IEEE WTG Modeling Panel, Session July 2003.
10. Wind Energy Basics. [Online]. Available:
http://windeis.anl.gov/guide/basics/.

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