i

PID-HYSTERESIS VOLTAGE CONTROL TECHNIQUE FOR THREE PHASE

INDUCTION MOTOR (MATLAB SIMULINK AND ARDUINO)

AMMAR HUSAINI BIN HUSSIAN

A project report submitted in partial

fulfillment of the requirement for the award of the

Degree of Master Of Electrical Engineering

Faculty of Electrical Engineering

Universiti Tun Hussein Onn Malaysia

JANUARY 2014

iv

ABSTRACT

These phase induction motors are the most widely used electric motors in industry for

converting electrical power into mechanical power. They are considered to be simple,

rugged, robust, efficient and suitable for applications in harsh environment. However,

their controllability remains a difficult task using conventional control method. The

control difficulty is associated with high nonlinearity of the motor’s behavior,

complexity of its analytical model and presence of interactive multivariable structures.

Therefore, this project is proposed a design controller for three phase induction

machines in high performance application. The PID Hysteresis controller is developed

and simulates using MATLAB/Simulink software and downloads to Arduino where

generates the PWM signal. The signals then send to gate driver of a three phase inverter

to give a stable performance to the induction motor. The improvement of performance

is by comparing the actual measured voltage of the motor with respect to their reference

voltage. The difference is then corrected thus minimizing the voltage error. A simple

hardware implementation of the PID Hysteresis voltage controller is designed and some

simulation and experimental results are presented to demonstrate the validity of this

approach.

v

ABSTRAK

Projek ini menerangkan pengawal untuk motor aruhan tiga fasa. Motor aruhan adalah

sebuah penggerak elektromekanikal yang digunakan secara meluas kerana kos

penyelenggaraan yang rendah dan boleh dipercayai. Walau bagaimanapun, masalah

kawalan motor aruhan adalah kompleks kerana tidak linear, gangguan tork beban dan

parameter yang tidak menentu. Elemen yang dimasukkan dalam projek ini adalah

kawalan voltan, yang mahu mengawal voltan dari inverter tiga fasa ke motor aruhan

tiga fasa. Pengawal histeresis telah digunakan dalam projek ini untuk mengurangkan

ralat voltan. Pengawal histeresis dilihat sebagai mundur fasa input–output. Pelaksanaan

histeresis direka sebagai pengawal dilakukan dalam simulasi menggunakan MATLAB

Simulink. Di samping itu, perkakasan disediakan dan eksperimen dijalankan untuk

memerhati dan menganalisis model tersebut.

vi

CONTENTS

TITLE i

DECLARATION ii

ACKNOWLEDGEMENT iii

ABSTRACT iv

CONTENTS vi

LIST OF FIGURE ix

LIST OF TABLE xii

LIST OF SYMBOLS AND ABBREVIATIONS xiii

CHAPTER 1 INTRODUCTION 1

1.1 PROJECT BACKGROUND 1

1.2 PROBLEM STATEMENT 2

1.3 OBJECTIVE 3

1.4 SCOPE 3

CHAPTER 2 LITERATURE REVIEW 4

2.1 INDUCTION MOTOR 4

vii

2.1.1 THREE PHASE INDUCTION MOTOR 4

2.2 INVERTER DC TO AC 6

2.2.1 THREE PHASE INVERTER 6

2.3 ADAPTIVE CONTROLLER 7

2.3.1 PID CONTROLLER 8

2.3.2 FUZZY LOGIC CONTROLLER 9

2.4 PASSIVE CONTROLLER 10

2.4.1 HYSTERESIS 10

2.4.2 SLIDING MODE CONTROL 10

2.5 CONTROLLER 13

2.5.1 PROPOSED CONTROLLER 13

2.6 ARDUINO 15

CHAPTER 3 METHODOLOGY 17

3.1 BLOCK DIAGRAM OF THE PROJECT 17

3.2 THE PROJECT FLOWCHART 18

3.3 WORKING FLOWCHART 19

3.4 INVERTER DESIGN 20

3.5 GATE DESIGN 21

3.6 CONTROLLER DESIGN 22

3.6.1 ADC 23

3.6.2 DAC 23

3.7 VOLTAGE SENSOR TECHNIQUE 26

viii

3.8 FILTER 27

CHAPTER 4 DATA ANALYSIS AND RESULT 29

4.1 SIMULATION RESULT AND ANALYSIS 29

4.2 OPEN LOOP CONTROL ANALYSIS 33

4.3 CLOSED LOOP ANALYSIS FOR HARDWARE 37

4.3.1 THE WAVEFORM AT CURRENT SENSOR 38

4.3.2 THE WAVEFORM BEFORE TRANSFORMER 39

4.3.3 THE WAVEFORM AFTER TRANSFORMER 41

4.3.4 EFFECT ADD AN OFFSET 43

4.4 THE COMPARISON BETWEEN SIMULATION AND 45

HARDWARE

CHAPTER 5 CONCLUSIONS 49

5.1 CONCLUSION 49

5.2 FUTURE WORKS 50

REFERENCES 51

APPENDIX A 55

APPENDIX B 57

APPENDIX C 60

APPENDIX D 61

APPENDIX E 64

ix

LIST OF FIGURE

2.1 Three phase induction motor. 5

2.2 Standard three-phase inverter 6

2.3 Basic configuration for an adaptive control system 7

2.4 PID controller block diagram 8

2.5 Basic hysteresis controller 11

2.6 Boundary layer 12

2.7 Hysteresis voltage control operation waveform 14

2.8 The Arduino microcontroller 16

3.1 Block diagram of the project 17

3.2 The project flowchart 18

3.3 Working flowchart 19

3.4 Schematic circuit of three phase inverter 20

3.5 The three phase inverter of hardware 20

3.6 Schematic diagram of gate driver for inverter 21

3.7 The hardware of gate driver for three phase inverter 21

3.8 PID Hysteresis controller 22

3.9 Analog-digital-converter. 23

x

3.10 Digital-analog converter 23

3.11 Function block parameter of PID 24

3.12 LED blinking likes PWM (pre-testing) 25

3.13 The expectation for PWM produces from Arduino 25

3.14 The sketching for signal after add an offset 26

3.15 The hardware for voltage sensor technique 27

3.16 The circuit for the filter 27

4.1 PID Hysteresis controller using MATLAB simulation 29

4.2 The function block parameter of discrete 2nd

order filter 30

4.3 ADC output and DAC output 31

4.4 Simulation of error in controller 31

4.5 Result simulation of PWM signals 32

4.6 The result simulation after through the transformer 32

4.7 The result simulation after filtering with discrete 2nd

order 33

4.8 Open loop simulation using MATLAB simulink 33

4.9 The overall of model hardware for this project 34

4.10 The waveform result of the hardware at sensor current 35

4.11 The waveform result hardware after inverter before through 35

the transformer

4.12 The waveform result hardware after transformer 36

4.13 The result waveform after add an offset 36

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4.14 Simulink models for closed loop PID hysteresis controller 37

4.15 The waveform at current sensor injected 10Vdc 38

4.16 The waveform at current sensor injected 20Vdc 38

4.17 The waveform at current sensor injected 30Vdc 38

4.18 The waveform before Transformer injected 10Vdc 39

4.19 The waveform before Transformer injected 20Vdc 39

4.20 The waveform before Transformer injected 30Vdc 40

4.21 The waveform after transformer with injected 10Vdc 41

4.22 The waveform after transformer with injected 20Vdc 41

4.23 The waveform after transformer with injected 30Vdc 42

4.24 The waveform after add an offset with injected 10Vdc 43

4.25 The waveform after add an offset with injected 20Vdc 43

4.26 The waveform after add an offset with injected 30Vdc 44

4.27 The simulation result after inverter 45

4.28 The hardware result after inverter 45

4.29 The simulation result after transformer 46

4.30 The hardware result after transformer 46

4.31 The simulation result add offset 47

4.32 The hardware result add offset 47

xii

LIST OF TABLE

2.1 Specifications of Arduino 15

4.1 The value of voltage at open loop condition for the hardware 36

4.2 The gain calculated by using DAC equation 38

4.3 The comparison between variable voltage supply and the 39

current Irms

4.4 The comparison between injected voltage and Vrms after 40

three phase inverter

4.5 The scale down of voltage after transformer 42

xiii

LIST OF SYMBOLS AND ABBREVIATIONS

V - Voltage

DC - Direct current

AC - Alternating current

Vac - Alternating current voltage

VSI - Voltage source inverter

CSI - Current source inverter

PID - Proportional integral derivative

PWM - Pulse width modulation

DSP - Digital signal processing

r.m.f. - Rotating magnetic field

DFO - Direct field-oriented

FFT - Fast fourier transform

IC - Integrated circuit

SMC - Sliding mode controller

DTC - Direct torque ratio

USB - Universal serial bus

ADC - Analog to digital converter

DAC - Digital to analog converter

xiv

IPM - Interior permanent magnet

ICSP- - In circuit serial programming

1

CHAPTER 1

INTRODUCTION

1.1 Project Background

One of the most common electrical motor used in most applications which is known

as Induction Motor. This motor is also called as asynchronous motor because it runs

at a speed less than synchronous speed. Induction motor is widely used in industry

because of its reliability and low cost, either single phase or three phases. However,

three phases induction is the most interesting and has attracted the attention of many

researchers because of induction motor is strongly nonlinear [1].

The function of three phase inverter to Induction motor is produced the 6 pulse PWM

signals where the three phase induction motor based on three phase with different

shifting time. Many controllers have been developed, that can be divided into two

classifications, passive and adaptive power controller. The example for passive

power controller is hysteresis, relay and sliding mode control and for adaptive power

controller is Proportional Integral Derivatives (PID), fuzzy, and P-resonant

controller. Each of them has their advantages, such as simple structure and low

maintenance cost [2].

Inverters that use PWM switching techniques have a DC input voltage that is usually

constant in magnitude. The inverters job is to take this input voltage and output ac

where the magnitude and frequency can be controlled. Many applications that require

an inverter use three phase power. The example is an ac motor drive. One option for

a three phase inverter is to use three separate single phase inverters but vary their

2

output by 120° [3]. The three phase inverter setup consists of three legs, one for each

phase. In three phase inverters PWM is used in the same way as it is before except

that it much be used with each of the three phases. When generating power to three

different phases one must make sure that each phase is equal, meaning that it is

balanced.

Nowadays, an embedded system such as Arduino is rapidly developed in many

applications. This is because the Arduino is the low cost other than else and it also an

open source [3]. Furthermore the Arduino also can be directly interfaced to the

MATLAB Simulink. In many applications of the induction motor, high performance

voltage control is one of the fundamental issues [4]. However, induction motors are

difficult to control because of their dynamics are intrinsically nonlinear and

multivariable and for feedback, it has a critical parameter such as load torque, stator

and rotor resistances which may considerably vary during operations [5]. That’s the

point why a strong controller like PID-Hysteresis control was chosen.

1.2 Problem Statement

The recent advances in the area of field-oriented control (FOC) bring the rapid

development and cost reduction of power electronics devices for three phase

induction motor give more economical for many industrial applications. However,

the control problem of the induction motor is complex due to the nonlinearities. It

has several parameters such as load torque, stator and rotor resistances which may

considerably vary during operations. There are exists of control strategies such as

even adaptive schemes tend to be sensitive but poor in the flux and torque estimation

especially during low speed operation. So the proposed here is to implement a design

PID-Hysteresis control modeling using MATLAB Simulink by injecting a corrected

voltage to the three phase inverter. The challenge in induction motor is to run at the

desired speed the voltage generated in the motor is the same as the applied operating

voltage. The processes that drive the induction motor are hard because it has electric

magnets in both side, the stator and in the rotor. The rotor windings are shorted and

act like the secondary windings of a transformer. The magnetic field rotating in the

stator induces a current in the shorted rotor windings, which then generates its own

magnetic field [10].

3

1.3 Objective

The objectives of this project are listed as follows:

1. To develop the PID Hysteresis controller approach for motor control.

2. To implement hardware of induction motor drives that is voltage control

using PID Hysteresis Controller carried by Arduino embedded devices.

3. To simulate and design the PID Hysteresis control model by using MATLAB

Simulink.

4. To analyze the PID Hysteresis Controller.

1.4 Scope

In this project the scope of work will be undertaken in the following three

developmental stages:

1. Study of the control system of induction motor for voltage control based on

PID Hysteresis control.

2. Perform simulation of PID Hysteresis control. This simulation will be carried

out on MATLAB platform with Simulink as it user interface.

3. Development of the target MATLAB Simulink model to Arduino and

implements the hardware of voltage control of induction motor for PID

Hysteresis Controller.

4

CHAPTER 2

LITERATURE REVIEW

2.1 Induction motor

The principles of motor is when a current-carrying conductor is located in an external

magnetic field perpendicular to the conductor, the conductor experiences a force

perpendicular to itself and to the external magnetic field.

2.1.1 Three phase induction motor

Induction motor also called asynchronous motor in motor. All the rotor's energy is

produced from the magnetic field of the stator winding to electromagnetic induction .

An induction motor not requires mechanical commutation for all or part of the

energy transferred from stator to rotor. An induction motor's rotor can be both

wound and the type. Three squirrel-cage induction motors are widely used in

industrial drives because they are rugged, reliable and economical. Single-phase

induction motors are used extensively for smaller loads, such as household

appliances like fans. One of the advantages of an induction motor is its mechanical

simplicity. This leads to not only to inherent reliability, but also to simpler design for

shock requirements. Through careful motor and system design, it has been possible

reduce structure borne noise signatures to levels that permit hard mounting of the

motor to the hull of a surface combatant [5].It also easy to program for its various

uses and low maintenance cost. The Hence for fine speed control applications dc

motors are used in place of induction motors. Disadvantage is that speed control

of induction motors is difficult.

5

In paper [6] had presented novel field-weakening scheme for the induction machine.

The proposed algorithm, based on the voltage control strategy, ensures the maximum

torque operation over the entire field-weakening region without using the machine

parameters. Also, they had introduced the direct field-oriented (DFO) control, which

is insensitive to the variation of machine parameters in the field-weakening region,

the drive system can obtain robustness to parameter variations. Lastly, they founded

Experimental results for the laboratory induction motor drive system confirms the

validity of the proposed control algorithm.

In paper [7] had presented hysteresis control method for three-phase current

controlled voltage-source PWM inverters. It minimizes interference among phases,

thus allowing phase-locked loop (PLL) control of the modulation frequency of

inverter switches. Then they had discussed about control theory, and described the

controller implementation. Design criteria are also given. The results of experimental

tests show excellent static and dynamic performance.

The advantages of the three phase induction motor are it has simple and rugged

construction, it is relatively cheap, requires little maintenance, it also has high

efficiency and reasonably good power factor. Lastly it has self starting torque. The

disadvantages are it is essentially a constant speed motor and its speed cannot be

changed easily. Its starting torque is inferior to DC shunt motor. The Figure 2.1

shows the three phase induction motor.

Figure 2.1: three-phase induction motor

6

2.2 Inverter DC to AC

An electrical power converter which is changes direct current DC to alternating

current AC is called power inverter. It can be any required of voltage and frequency

usually used in transformer , switching and control circuit. It also used from small

switching power supplies to large high-voltage electric equipments applications that

transport bulk power and solid-state inverters have no moving parts. Commonly

inverter is used to supply solar panels or batteries and it perform the opposite

function of a rectifier. The electrical inverter is high-power electronic oscillator

because generally AC to DC converter was made to work in reverse and thus was

inverted which is to convert DC to AC.

2.2.1 Three-phase inverter

Three-phase inverter circuit works at line-frequency, which the main output power.

The switches work at line frequency, so the switching loss is small and the efficiency

of output syetem is high [6].The three-phase inverter the main output power; three

single-phase full-bridge inverters are used to improve the system dynamic

performance. Compared with the traditional inverter circuit, the circuit can achieve

high efficiency and low harmonics at the same time, and it can also reduce the

voltage stress of the power switches. This is a new way for the combination of the

inverters. The circuit can be controlled easily, so it was easy to be modularized. High

frequency inverter used PWM modulation and line-frequency inverters worked.

Figure 2.2. : standard three-phase inverter

7

The standard three-phase inverter shown in Figure 2.2. has six switches the switching

of which depends on the modulation scheme. The input dc is usually obtained from a

single-phase or three phase utility power supply through a diode-bridge rectifier and

LC or C filter.The PWM inverter A has most applications such as unintermptible

power systems (UPS'S), active filters, high power factor converters, and adjustable

frequency drives.Almost all applications of PWM inverters with a current minor

loop, and performance of the inverter system largely depends on the quality of the

current minor loop. Therefore current control of PWM inverter is one of the most

important subject of power electronics [7].

2.3 Adaptive controller

Basically controller devide into two categories which is adaptive and passive

controller. The example of adaptive controller is PID, Fuzzy and Neural Network.

Adaptive Control covers a set of techniques which provide a systematic approach for

automatic adjustment of controllers in real time, in order to achieve or to maintain a

desired level of control system performance when the parameters of the plant

dynamic model are unknown and/or change in time [8]. The Figure 2.3 below shown

the basic configuration for adaptive system.

Figure 2.3 : Basic configuration for an adaptive control system

The advantages of Adaptive Control is convenience controller so that it can

continuously adapt itself to the current behavior of the process and outperformed

their fixed parameter counterparts in terms of efficiency. It also can eliminate the

error faster and with fewer fluctuations. Allow the process to operate closer to its

constraints where profitability is highest but the disadvantage is much more complex.

8

2.3.1 PID Controller (Proportional Intergral and Derivative)

Proportional-integral-derivative(PID) controllers have been the most popular and the

most commonly used industrial controllers in the past years [9]. The popularity and

widespread use of PID controllers are at tributed primarily to their simplicity and

performance characteristics.Although linear fixed-gain PID controllers are often

adequate for controlling a nominal physical process, the requirements for high-

performance control with changes in operating conditions or environmental

parameters are often beyond the capabilities of simple PID controllers [10][11]. The

Figure 2.4 shows the PID controller block diagram.

P

I PROCESS1 1

errorsetpoint

measured

disturbance

output

Kp e(t)

Ki e(t2)dt2

8

t

D

SENSOR

Kdde(t)

dt

Figure 2.4 : PID controller Block Diagram

( ) ( ) ( ) ∫ ( )

( ) (2.1)

= proportional gain, a tuning parameter.

= integral gain, a tuning parameter.

= derivative gain, a tuning parameter.

= error.

= time or instantaneous time

9

In Proportional Derivative Integral mode, the controller make the following:

- Multiplies the Error by the Proportional Gain (Kp), Added to the Derivative

error multiplied by Kd and Added to the Integral error multiplied by Ki, to

get the controller output.

The advantages of PID controller is using both integral and derivative control (PID)

has removed steady-state error and decreased system settling times while

maintaining a reasonable transient response.

2.3.2 Fuzzy logic controller

Fuzzy logic control is one of the most interesting fields where fuzzy theory can be

effectively applied. Fuzzy logic techniques attempt to imitate human thought

processes in technical environments. Fuzzy control also supports nonlinear design

techniques that are now being exploited in motor control applications. Initially fuzzy

control was found particularly useful to solve nonlinear control problems or when the

plant model is unknown or difficult to build. The present work includes application

of fuzzy techniques to control the speed of an induction motor. Fuzzy rules can be

obtained through machine learning techniques, where the knowledge of the process

is automatically extracted or induced from sample cases or examples. Many machine

learning methods developed for building classical crisp logic systems can be

extended to learn fuzzy rules [12]. The adaptive fuzzy control can compensate for

any under estimation of the bounds of the uncertainties [13]. However, the

performance may still be unsatisfactory when the machine parameters vary too

much. The basic reason for the unsatisfactory performance is that the control

algorithms lack the ability to learn how to deal with the system complexity. Results

of comprehensive computer simulation show that fuzzy model reference leaning

control (FMRLC) has potential to improve the close-loop control performance

[14][15].Limitations Of Fuzzy Logic Controller is hard to develop a model from a

fuzzy system and require more fine tuning and simulation before operational.

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2.4 Passive controller

Normally controller divides into two groups, they are adaptive and passive. The

example the passive controller is consists of hysteresis, relay and sliding mode

control. Passivity is a property of engineering systems, used in a variety of

engineering disciplines, but most commonly found in analog electronics and control

systems. A passive component, depending on field, may be either a component that

consumes but does not produce energy thermodynamic passivity, or a component

that is incapable of power gain (incremental passivity).

2.4.1 Hysteresis

The hysteresis is the dependence of a system not only on its current environment but

also on its past environment. Some significant advantages of hysteresis controllers

overother types of controllers designed with linear or nonlinear control techniques

are as follows:

• switching behavior of the power inverter can be directlytaken into account at the

design level.

• robustness to load parameters’ variation can be proved.

• almost static response is achieved (the dynamics are obviously bounded by the dc-

link voltage and by the actual switching frequency).

• simple hardware implementation, based on logical devices, is possible according to

the Boolean nature of controller input/output variables.

However, conventional type of hysteresis controllers (with independent comparator

for each phase of the load) suffers from some well known drawbacks, e.g., limit

cycle oscillations, overshoot in current errors, generation of sub harmonic

components in the current and random (non-optimum) switching[16]. The figure

below shown the basic hyteresis controller. The Figure 2.5 shows the basic hysteresis

controller.

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Figure 2.5 : basic hysteresis controller.

Hysteresis occurs in ferromagnetic materials and ferroelectric materials, as well as in

the deformation of some materials (such as rubber bands and shape-memory alloys)

in response to a varying force. In natural systems hysteresis is often associated with

irreversible thermodynamic change. Many artificial systems are designed to have

hysteresis: for example, in thermostats and Schmitt triggers, hysteresis is produced

by positive feedback to avoid unwanted rapid switching. Based on the electrical

engineering, Hysteresis can be used to filter signals so that the output reacts slowly

by taking recent history into account.

A three-level inverter-fed induction motor drive operating under Direct Torque

Control (DTC) is presented. A triangular wave is used as dither signal of minute

amplitude (for torque hysteresis band and flux hysteresis band respectively) in the

error block. This method minimizes flux and torque ripple in a three-level inverter

fed induction motor drive while the dynamic performance is not affected. The

optimal value of dither frequency and magnitude is found out under free running

condition. The technique can reduces torque ripple by 60% (peak to peak) compared

to the case without dither injection, results in low acoustic noise and increases the

switching frequency of the inverter [17].

2.4.2 Sliding mode control (SMC)

The major advantage of a sliding-mode controller is its insensitivity to parainetcr

variations and external load disturbance once on the switching surface.The SMC is

found to be attractive in terms of robustness of the drive response but suffers from

the problem of chattering,apart from being slightly difficult to realize [1]. The Figure

2.6 shows the baundary layer for SMC.

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Boundary

layer

Manifold s(x)=0

State

trajectory

s(x)=0

sm(x)=0

Figure 2.6: Boundary layer

There is definition of terms in sliding mode control:

State Space – An n-dimensional space whose coordinate axis consist of the x1

axis, x2 axis until xn axis.

State trajectory- A graph of x(t) verses t through a state space.

State variables – The state variables of a system consist of a minimum set of

parameters that completely summarize the system’s status.

Disturbance – Completely or partially unknown system inputs which cannot

be manipulated by the system designer.

Sliding Surface – A line or hyperplane in state-space which is designed to

accommodate a sliding motion.

Sliding Mode – The behavior of a dynamical system while confined to the

sliding surface.

Reaching phase – The initial phase of the closed loop behavior of the state

variables as they are being driven towards the surface.

The sliding mode control approach for induction motor drives is based on the model

of an induction motor in a frame rotating synchronously with the stator current

vector. As with the indirect vector control of induction motor, the method allows

rotor flux and torque to be controlled by two independent control variables. Since the

control law is represented in a set of inequalities instead of equalities, as the motor

parameters change, the stability of the sliding mode and the feature of independent

control of the flux and torque will not be destroyed as long as the corresponding

inequalities hold stated in paper C.C.Chan, H.Q. Wang [18].

13

The SMC does not need accurate mathematical model but requires knowledge of

parameter variation range to ensure stability and satisfy reaching conditions. As the

power converters are highly variable structured, sliding mode control offers several

advantages, such as stability even for large supply and load variations, robustness,

good dynamic response and simple implementation.

2.5 Controller

In three phase induction motor, there are two technique for controller which is

voltage source control technique and the current source technique. Both of the

control technique quite same in terms of comprising an internal voltage/current

feedback loop and correct the error occurs using the adaptive or adaptive controller

to make the correction in terms to control the performance of the induction

motor.Error in the current controller degrades the drive's performance in the same

way as de-tuning the field orientation control.Another current control technique

involves de-coupling of the motor emf voltage to improve the performance of the

current regulation [19].

2.5.1 Proposed controller

Adaptive-Passive controller is a main controller for this project. Voltage source

control technique for PID Hysteresis mode controller will propose to be a controller.

It is because PID control is the gold standard for most moving machines, and quite

adequate in most applications that require closed-loop control. However, it's

vulnerable to disturbances, and tuning can be tedious. For these reasons, some

industrial drives go beyond traditional PID structures and servo algorithms for

position control with sliding mode that increase stability over a wider range of

conditions, to make tuning easier for design engineers.

PID control is limited, as it depends on a plant model, so is sensitive to real-world

parameter variations and disturbances such as motor and load inertia changes. In

contrast, Hysteresis controller has a much simpler control structure. Unlike other

advanced servo algorithms, Hysteresis control structure is simpler. Its performance

and ease of use are comparable to that of competitive technologies. Another

14

advantage of Hysteresis control is that the majority of applications need only

manipulate one parameter to achieve optimal performance making it easier to use.

In this project also, a voltage source control technique is a part of the controller to

control the voltage that supply to the induction motor. The voltage source control

technique operate by comparing the voltage line to line (to three induction motor)

with a voltage reference(as a reference voltage) and the error will send to PID

Hysteresis to minimize the error. The PID Hysteresis will minimize the error by

sending a Pulse Width Modulation (PWM) to a three phase inverter

.

Figure2.7: Hysteresis voltage control operation waveform.

The voltage controllers of the three phases are designed to operate independently.

Each voltage controller determines the switching signals to the inverter. The

switching logic for phase A is formulated as below:

If Va < (Varef -HB) upper switch (G1) is OFF and lower switch (G4) is ON

If Va < (Varef +HB) upper switch (G1) is ON and lower switch (G4) is OFF

In the same action, the switching of phase B and C are derived but in different phase

shift that is phase B in 120° shift and phase C in 240° shift.

15

2.6 Arduino

In 2005, Massimo Banzi and David Cuartielles was made of one embedded system

named as Arduino which are less expensive than other prototyping systems available

at the time. They began producing boards in a small factory located in Ivrea, a town

in the Province of Turin in the Piedmont region of northwestern Italy.Arduino is a

single-board microcontroller designed to make the process of using electronics in

multidisciplinary projects more accessible. The hardware consists of a simple open

source hardware board designed around an 8-bit Atmel AVR microcontroller, though

a new model has been designed around a 32-bit Atmel ARM. The software consists

of a standard programming language compiler and a boot loader that executes on the

microcontroller [16]. Micro- controllers are also attracted to Arduino because of its

agile developement capabilities and its facility for quick implementation of ideas.The

Arduino is a microcontroller board based on the ATmega328 (datasheet). It has 14

digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a

16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a

reset button. It contains everything needed to support the microcontroller; simply

connect it to a computer with a USB cable or power it with a AC-to-DC adapter or

battery to get started. The Uno differs from all preceding boards in that it does not

use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2

(Atmega8U2 up to version R2) programmed as a USB-to-serial converter [16].There

are specifications of Adruino:

Table 2.1: Specifications of Arduino

Microcontroller Atmega328

Operating Voltage 5V

Input Voltage (recommended) 7-12V

Input Voltage (limits) 6-20V

Digital I/O Pins 14 (of which 6 provide PWM output)

Analog Input Pins 6

DC Current per I/O Pin 40 mA

DC Current for 3.3V Pin 50 mA

Flash Memory 32 KB (Atmega328) of which 0.5 KB used by

16

bootloader

SRAM 2 KB (Atmega328)

EEPROM 1 KB (Atmega328)

Clock Speed 16 MHz

The advantages of the Arduino are stated below:

Inexpensive - Arduino embedded devices are inexpensive compared to other

microcontroller embedded devices.

Cross-platform - Most microcontroller systems are limited to Windows.

Different with Arduino, it can runs on Windows, Macintosh OSX, and Linux

operating systems.

Simple, clear programming environment - The Arduino programming

environment is easy to use for beginners.

Open source - The Arduino software is published as open source tools, so the

user easy to get the information experienced programmers.

The applications of the embedded system like the Arduino rapidly growth due to the

advantages it. According to the paper [17], a novel Open loop phase control method

is developed by coding a program using ARDUINO software in which ARDUINO

controller takes input from the user and generates firing pulses for the TRIAC which

controls the speed of the Induction motor. The total process is executed with the help

of an ARDUINO controller kit where ARDUINO and Tera-Term softwares are used

for micro controller and for serial monitor. The Figure 2.8 shows the Arduino

microcontroller,

Figure 2.8: The Arduino microcontroller

17

CHAPTER 3

METHODOLOGY

3.1 Block diagram

Three-phase

inverterDC

Three-phase

induction

motor

PID HYSTERISIS

CONTROLLER

V ref

PWM

Figure 3.1: Block diagram of the project

The Figure 3.1 above shows the block diagram of the project. For this project its

consists of four mains parts which is the DC source as the input, the three phase

inverter, the three phase induction motor as a load and the controller to give the

system to a robustness performance. The first part is the input. The input for this

project is the DC voltage that fed to a three phase inverter. As the input it will give

the power to whole system. Second part is the three phase inverter. The general

function of the inverter is to convert the DC voltage to the AC voltage. But for this

18

system, the three phase inverter will be used because it will depend on the outputs

that are used. The six switch of switching inverter will be used because the PWM

will be fed from the controller. The load that is used is the three phase induction

motor. So the performance of the motor will be observed in terms of motor current

and the speed. The three phase induction motor is well known of its non linear

characteristics and for that reason the controller is needed to improve the

performance of the induction motor. The important part is the controller of the

system which is the voltage source control technique and PIDH will act as a

controller to the system. The controller will compare the motor current with the

reference current and if there is an error, the controller will generate the pulse width

modulation to feed into the three phase inverter. By fed the PWM to the inverter the

inverter will rescale the output to power up the load. By adding the controller to the

system it can give high level of performance of the induction motor.

3.2 Project flowchart

The flowchart below will explained how the system will operate from the starting to

end process. The Figure 3.2 of the project flowchart:

START

DC SUPPLY

TO INVERTER

INVERT DC TO

THREE PHASE

AC

POWER UP THE

THREE PHASE

INDUCTION

MOTOR

MOTOR VOLTAGE

= REFERENCE

VOLTAGE

CONTROLLER

GENERATETHE PWM

END

YES

NO

Figure 3.2: The project flowchart

19

3.3 Working flowchart

The Figure 3.3 shows the flow chart of work for this project from the beginning until

the ending. The challenging part is the controller part which is consists several

parameters that must be considered to accomplish this project successfully.

start

Software part

[MATLAB simulink]

Study the structure of

three-phase induction

motor

Derive mathematical

modeling of three-

phase induction motor

PID Hysteresis

control design

Hardware part

Study three-

phase inverter

Study the three-

phase induction

motor

Hardware setup

no

Time response meet

requirement

Upload to Adriano

Observe performance

of controller

Write thesis

end

yes

Figure 3.3: Working flowchart

20

3.4 Inverter Design

The circuit of three phase inverter design by using Proteus software. In this circuit,

the MOSFET (SPP11N60C3) is used with voltage rating till 600V which

accommodate the three phase inverter PWM. This inverter is connected from gate

driver to control the 6 switching PWM before it transfer to the Induction Motor. This

Figure 3.4 shows the schematic circuit for three phase inverter:

Figure 3.4: schematic circuit of three phase inverter

The capacitor with value 470uF is used to storage the energy with voltage rating up

to 400V. The hardware of three phase inverter is showing in Figure 3.5. The 2 port at

the left hand side below the capacitor is the Vdc input, the six positive and negative

(red and black wire) is the PWM switching signal and the three ports at right hand

side is the output phase A, B and C in Vac that will fed to induction motor.

Figure 3.5: the three phase inverter of hardware

21

3.5 Gate Design

Figure 3.6: schematic diagram for gate driver for inverter

The Figure 3.6 above shows the schematic diagram for gate driver inverter by using

PROTEUS software. From the Arduino, three signals were sent to the gate driver

inverter. It had change to six pulse signal after trough IC7414 (NOT gates) which is

one signal same likes original and one signal is invert from original. Then, IC4081

(quad two core or AND gate) as a function to double up the amplitude. The function

HCPL3120 is as a driver for power of MOSFET. The IL0515S supply to HCPL3120

with 15V to operate. The minimum of voltage to power up the MOSFET at three

phase inverter is 12V.Figure 3.7 shows the hardware of gate driver for three phase

inverter.

Figure 3.7: the hardware gate driver for three phase inverter

22

3.6 Controller Design

Figure 3.8.: PID Hysteresis controller

Figure 3.8 shows the MATLAB simulink of PID Hysteresis voltage controller .The

input voltage with amplitude 18V is injected to the controller before it compared

with the voltage reference. The functional of ADC and DAC are used to make likes

Arduino system where the Arduino are accepted the digital signal from the Induction

Motor waveform and then convert it to analog again. Electronic equipment is

frequently used in different fields such as communication, transportation,

entertainment, etc. Analog to Digital Converter (ADC) and Digital to Analog

Converter (DAC) are very important components in electronic equipment. Since

most real world signals are analog, these two converting interfaces are necessary to

allow digital electronic equipments to process the analog signals.

An Analog to Digital Converter (ADC) is a device for converting an analog signal

(current, voltage etc.) to a digital code, usually binary. In the real world, most of the

signals sensed and processed by humans are analog signals. Analog-to-Digital

conversion is the primary means by which analog signal are converted into digital

data that can be processed by computers for various purposes.

Digital to Analog Converter (DAC) is an inverse function of ADC. In order to get

back the signal that can be processed or sensed by humans or equipment.

23

3.6.1 ADC

Figure 3.9: Analog-digital-converter

Figure 3.9 shows the diagram to convert analog signal to digital signal. The value of

analog signal is 20Vac with convert 10 bits, 1023. From here the equation will

calculated to generate the ADC equation.

(3.1)

( )

For(20,1023);

( )( )

So the ADC equation is;

3.6.2 DAC

Figure 3.10: digital-analog converter

24

Figure 3.10 shows the diagram of digital to analog converter. Same with ADC, the

DAC equation must be calculated as follows:

( )

For(1023,20);

( )( )

So the DAC equation is;

The signal after the converters are compared via voltage reference with the amplitude

is 20 and then correcting the error feedback from the induction motor. The error will

filtering with PID controller first which is the PID must be setup with

Kp=1(proportional), Ki=0.1 (integral) and Kp=0 (Derivative).The figure 3.11 below

shown the function block parameter of PID controller:

Figure 3.11: function block parameter of PID

The signal after PID will be filtering again by Hysteresis controller to produce the

constant PWM. The constant values 0.2 is used to cutoff the waveform from PID and

then make the different shifting between phase. The Figure 3.12 shows the

connection between MATLAB software with Arduino with the LED signal acting

likes the PWM signals before injected to the gate driver of three phase inverter. The

51

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