pid-hysteresis voltage control technique for...
TRANSCRIPT
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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.
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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.
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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
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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
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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
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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
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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].
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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.
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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
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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
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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.
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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
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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
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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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