Torque Control

School of Electronic, Communication and Electrical Engineering BEng Final Year Project Report

0

FEI GAO/ Torque control for the brushless ac motor based on blackfin

UNIVERSITY OF HERTFORDSHIRE

Faculty of Engineering & Information Sciences

School of Electronic, Communication and Electrical

Engineering

BACHELOR OF ENGINEERING DEGREE WITH

HONOURS IN

ELECTRICAL AND ELECTRONIC ENGINEERING

Final Year Project Report

Torque control for the brushless ac motor based on

blackfin

Report by

GAO FEI

Supervisor

George Pissanidis

Date

APRIL 2010


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DECLARATION STATEMENT

I certify that the work submitted is my own and that any material derived or quoted

from the

published or unpublished work of other persons has been duly acknowledged (ref.

UPR

AS/C/6.1, Appendix I, Section 2 – Section on cheating and plagiarism)

Student Full Name: FEI GAO

Student Registration Number: 08199095

Signed: …………………………………………………

Date: 13 April 2008


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ABSTRACT

This project is based on three phase brushless AC motor (BACM) on

Blackfin, using visual DSP++ with C programming to control it. Field

Orientated Control of 3-Phase AC-Motors is discussed. The BACM

current control modules are used in programming. Pulse Width

Modulation (PWM), A/D converter and inverter are also illustrated. The

C programming code is written by software named visual DSP++ 5.0 to

control operation. Some research and analysis of hardware components

are explained. Finally, the program is fine tuned for improvement and the

possibility of further development assessed.


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ACKNOWLEDGEMENTS

I would like to thank my project supervisor George Pissanidis for his

unconditional technical support and guidance throughout. Although I

have studied the issue very slow, he patiently helped me.


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TABLE OF CONTENTS

DECLARATION STATEMENT ................................................................1

ABSTRACT................................................................................................2

ACKNOWLEDGEMENTS........................................................................3

TABLE OF CONTENTS............................................................................4

LIST OF FIGURES ....................................................................................7

GLOSSARY ...............................................................................................9

1. Introduction.........................................................................................10

1.1 Aims and objectives......................................................................10

1.2 Background...................................................................................10

1.3 overview of project work..............................................................11

2. Background Theory ............................................................................11

2.1 Brushless AC motor......................................................................11

2.1.1 theory of brushless AC motor..............................................11

2.1.2 Advantage of brushless AC motor .......................................13

2.2 PWM unit......................................................................................14

2.2.1 Theory of PWM...................................................................15

2.3 A/D converter................................................................................16

2.4 Inverter..........................................................................................17

2.5 PID controller theory ....................................................................17


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3. Field Orientated Control of 3-Phase AC-Motor [5]............................18

3.1 Space Vector definition and projection.........................................19

3.1.1 (a,b,c) →(α,β) (the Clarke transformation) .........................20

3.1.2 (a,b) →(d,q) (the Park transformation)................................21

3.1.3 (a,b) →(d,q) (inverse Park transformation).........................21

3.2 The basic scheme for the FOC......................................................22

3.3 The input for the FOC...................................................................23

3.3.1 current sampling ..................................................................23

3.3.2 Rotor flux position...............................................................23

4. BACM current control modules .........................................................25

5. Design .................................................................................................27

6. Programming ......................................................................................28

6.1 S function model code ..................................................................28

6.2 Main comments.............................................................................30

7. Results.................................................................................................31

7.1 initialization process .....................................................................32

7.2 speed control .................................................................................33

7.3 position control .............................................................................34

8. Conclusion and further development..................................................34

8.1 Further development .....................................................................35

9. Projection time plan ............................................................................36


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10.References............................................................................................37


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LIST OF FIGURES

Figure 1 sample brushless motor ........................................................12

Figure 2 PWM signals [2]...................................................................14

Figure 3 A/D converter chip [3]..........................................................16

Figure 4 Basic scheme of 3-phase inverter and AC motor [5] ...........17

Figure 5 PID controller [6] .................................................................17

Figure 6 Stator current space vector and its component in (a,b,c) .....19

Figure 7 Stator current space vector and its components in (a,b) ......20

Figure 8 Stator current space vector and its component in (a,b) and in

the d,q rotating reference frame....................................................21

Figure 9 Basic scheme of FOC for AC-motor....................................22

Figure 10 motor control systems ........................................................22

Figure 11 Current, voltage and rotor flux space vectors in the d,q

rotating reference frame and their relationship with a,b,c and α,β

stationary reference frame ............................................................24

Figure 12 Block diagram of the BACM torque control .....................25

Figure 13 the block diagram (a)............................................................0

Figure 14 the block diagram (b) ...........................................................0

Figure 15 current trajectories of vector control in initialization.........32

Figure 16 Speed command, actual speed waveform ..........................33


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Figure 17 waveform of position command, the actual location .........34

Figure 18 project time plan.................................................................36


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GLOSSARY

A/DC Analog to Digital Converter

BACM Brushless AC Motor

BLDC Brushless DC Motor

FOC Field Orientated Control

PID control Proportion, Integration, Differentiation

PS Position sensor

PWM Pulse Width Modulation


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1. Introduction

This report mainly illustrates my final year project, it is torque control for the

brushless AC motor based on blackfin. This project is based on Digital Signal

Processing(DSP).The basic theory behind electronic motor controls is that the motor’s

speed, torque, and direction are managed by electronically switching or modulating

the voltages to the motor. The current level to the motor can also be managed

indirectly by modulating the motor’s voltage.

1.1 Aims and objectives

The aim of project is to develop torque control for the brushless ac motor based on

BlackFin and create a software environment for AC motor control. The project is

written by C programming and design software mainly.

The objective of project is to develop A/DC driver and vector control algorithm.

Analog-digital converter, ADC for short is a device that the analog is converted to

digital. In the computer control system, should be checked to a variety of testing

devices. Continuously variable voltage or current as analog provide controlled object

of related parameters (such as speed, pressure, temperature, etc.) and control. The

input of computer should be the digital, so it need ADC to control.

1.2 Background

In recent years, brushless motor in the rapid development in the field model is a kind

of motivation. Because of the price, yield and over the past few years brushless motor

used in high-grade aviation model due to mechanical processing technology, now the

rapid development, the production cost of brushless motors dropped many, it is into

every aspect of field model from the electric control, electric car to remote-controlled

boats to electric model plane, everywhere.

Electric power electronics, electrical technology, the controller for the development of

technology progress of electromechanical industry provides a powerful force. And

often used in motor control are compared, the MCU control motor of brushless dc

motor (BLDC) motors and eliminate the phase change brush wear, improve the arc

stability of the control system and the life, power electronics device applications

greatly reduced the size of the control system, the control structure in industrial and

civil widely used in the field and the server application prospect


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1.3 overview of project work

Chapter 1 provides background material on brushless AC motor. Chapter 2 describes

theoretical analysis of how each component works. Chapter 3 provides theoretical

analysis and measurement of Field Orientated Control of 3-Phase AC-Motors.

Chapter 4 describes BACM current control modules in details. Chapter 5 has given

the some programming and comments. Chapter 6 presents the some results. Chapter 7

provides conclusions and further work.

2. Background Theory

2.1 Brushless AC motor

2.1.1 theory of brushless AC motor

Motor is electrical equipment that converted into electrical energy to mechanical

energy, and can re-use of machinery to produce kinetic energy, used to drive other

devices.

The following figure shows the theory of brushless motor simply


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Figure 1 sample brushless motor

Three coils are mounted 120 degrees apart. When current is applied to a coil it will

attract the nearest rotor magnet. If current is applied to the phase U coil, the rotor will

turn clockwise until magnet A is aligned with the coil (at a detent). This simple

brushless motor is similar to a how a stepper motor operates; turning on one coil will

cause the shaft to rotate by one magnet pole. [1]

Three-phase asynchronous motor to rotate together with the prerequisite is a rotating

magnetic field, the three-phase asynchronous motor stator windings is used to produce

a rotating magnetic field. We know, but in power phase-to-phase voltage difference in

phase is 120 degrees, three-phase asynchronous motor stator windings in three of the

spatial position also sent 120 degrees, so each stator winding, when in tube, conduct

the three-phase power, stator winding can produce a rotating magnetic field changes

every one cycle. Current, rotating magnetic field in space, namely a rotating magnetic

rotation of rotation speed and the current changes are synchronous. Rotating magnetic

speed for: n = 60f/P type of f for power frequency magnetic poles, P is the unit is the

logarithm, n.: RPM. According to the type we know, motor speed and number of poles

and the use of power frequency, therefore, ac motor speed control, there are two ways:

1, the change pole, 2, the frequency conversion method. Before the first method,

multi-purpose now use frequency conversion technology to realize stepless speed of

ac motor control


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2.1.2 Advantage of brushless AC motor

a. brushless and low interference

In addition to the brushless motor brush, the most immediate change is not a brush

motor running of edm, thus greatly reducing the spark of remote radio equipment.

b. Low noise and Smooth operation

Brushless motors no brush, reduce friction, the noise will run smoothly, and the

advantages of low many for the operation stability of model is a great support.

c. Long service life and low maintenance cost

Brushless motors wear primarily in the bearing, from the perspective of machinery,

brushless motor is almost a free maintenance of motor, when necessary, the need to do

some dust maintenance. A comparison, brushless motor brush motor is relative to the

advantages, but where everything is not absolute, low torque motor outstanding

performance, torque and characteristics of brushless motor is irreplaceable, but

brushless motors use convenient, as the cost of brushless controller and decline and

brushless technology development and market competition, high-speed brushless

power system is developed and popularized phase, it also has greatly promoted the

development of sports model.


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2.2 PWM unit

Figure 2 PWM signals [2]

Using PWM is the microprocessor for analog to digital output control of a kind of

very effective technology, widely used in measuring, communication with the

transformation to the power control in many areas.

The pulse width modulation (PWM) is a kind of digital signal level simulation coding.

Through the use of high resolution counter, the torque-current SHCH was used to

simulate a modulated signal code level. PWM signal is still in a given number,

because any moment, full of amplitude of the dc power supply or have (ON), or

completely without (OFF). Voltage or current source is a kind of tong (ON) or (OFF)

the sequence of pulse repetition is added to the analog load up. The time is dc power

supply is added to the load on the break, when the power is disconnected. As long as

bandwidth, any simulation value is enough to use a PWM coded.

Pulse width modulation is an analog control mode, its according to the corresponding

changes to the load of the base or modulation transistor the plates bias, to achieve a

switching power supply output crystal body tube or a time of change, this way can

make the power output voltage in working conditions change is constant, the digital

output by microprocessor control of analog circuit of a kind of very effective


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technology. PWM control technology with its simple, flexible and dynamic response

good advantage and become the most extensive application of power electronic

technology, the control mode is people study hotspot nowadays. Due to the

development of science and technology has no boundaries between subjects,

combining modern control theory thoughts or achieve harmonic soft switch

technology will become the PWM control technology is one of the main development

direction.

2.2.1 Theory of PWM

The analog signals, its value can be continuous variation amplitude of time and the

resolution are no restrictions. 9V battery is an emulator, because it is the output

voltage is not precisely 9V equal, but with time changing, and desirable any real value.

Similarly, the current is absorbed from the batteries in a group may not limit value

range. Analog and digital signal of the difference between the values of usually only

belong to pre-defined possible value set, for example in the 0V, 5V set of values.

Simulation can be directly used to the voltage and current control, such as the volume

of the radio control car. In the simulation of the radio, simple volume knob is

connected to a variable resistor. When the knob screw move, bigger or smaller

resistance, The current flows through the resistance will increase or decrease, which

changed the result, to drive the speaker volume corresponding bigger or smaller. With

the radio, the analog output and input into the linear scale.


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2.3 A/D converter

Figure 3 A/D converter chip [3]

An analog-to-digital converter (abbreviated ADC, A/D or A to D) is a device which

converts continuous signals to discrete digital numbers. The reverse operation is

performed by a digital-to-analog converter (DAC).

Typically, an ADC is an electronic device that converts an input analog voltage (or

current) to a digital number proportional to the magnitude of the voltage or current.

However, some non-electronic or only partially electronic devices, such as rotary

encoders, can also be considered ADCs. The digital output may use different coding

schemes, such as binary, Gray code or two's complement binary. [4]


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2.4 Inverter

Figure 4 Basic scheme of 3-phase inverter and AC motor [5]

The direct current (DC) transform into an alternating current (AC), its scientific terms

for the device inverter. Due to the change of frequency equipment or frequency

voltage inverter main device called ", "the product itself was named" inverter

".Usually, the voltage and frequency fixed ac frequency conversion variable voltage

or for the device called the ac inverter ".

In order to produce variable voltage and frequency converter (Inverter) must first turn

power an alternating current (AC) transform for the direct current (DC), the direct

current (DC) transform into an alternating current (AC). Used in motor control of

frequency converter, can change voltage and frequency of can be changed.

2.5 PID controller theory

Figure 5 PID controller [6]


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PID (proportional - integral - derivative) controller as the first practical use of the

controller has 50 years of history, is still the most widely used industrial controller.

PID controller is easy to understand, the use of accurate system models without

preconditions, thus to become the most widely used controller.

PID controller by the ratio of unit (P), integral unit (I) and the differential unit (D)

component. The input e (t) and output u (t) of the relationship

So its transfer function

Where the proportional coefficient Kp; TI for the integral time constant; TD for the

differential time constant

It is as versatile and flexible in use, there are series products, the use of only three

parameters to set (Kp, Ti and Td) can be. In many cases, does not necessarily need all

three elements, which can take one to two units, the ratio control unit is essential.

First, PID has wide range of applications. Although many industrial processes are

nonlinear or time-varying, but can become simplified through their basic non-linear

and dynamic characteristics of the system over time, this PID can be controlled.

Secondly, PID parameter tune easier. That is PID parameters Kp, Ti and Td according

to the dynamic nature of the process of setting time. If the process is dynamic,

changing, for example, changes may be caused by the load change in system

dynamics, PID parameters can be re-tuning.

Third, PID controller in practice also constantly improved

3. Field Orientated Control of 3-Phase

AC-Motor [5]

The Field Orientated Control (FOC) consists of controlling the stator currents

represented by a vector. This control is based on projections which transform a three


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phase time and speed dependent system into a two co-ordinate (d and q co-ordinates)

time invariant system. These projections lead to a structure similar to that of a DC

machine control. Field orientated controlled machines need two constants as input

references: the torque component (aligned with the q co-ordinate) and the flux

component (aligned with d co-ordinate)

3.1 Space Vector definition and projection

Three-phase current and voltage AC motors - and flux of the complex space can be

analyzed vector. For current space vector, can be defined as follows. ia, ib, ic is in the

stage of the stator instantaneous current, then the complex stator current is

defined by:

Where where and represent the spatial operators. The

following diagram shows the stator current complex space vector:

Figure 6 Stator current space vector and its component in (a,b,c)

(a, b and c) is the shaft three-phase system. The current space vector describing three

phase signal system. It also needs to transform into a two time constant coordinate


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system.

(a,b,c) →(α,β) (the Clarke transformation) which outputs a two co-ordinate time

variant

system

(a,b) →(d,q) (the Park transformation) which outputs a two co-ordinate time invariant

System

3.1.1 (a,b,c) →(α,β) (the Clarke transformation)

Figure 7 Stator current space vector and its components in (a,b)

Figure 7 shows The space vector can be reported in another reference frame with only

two orthogonal axis called (a,b). If the axis a and αare in the same frame.

the function shows The projection that modifies the

three phase system into the (a,b) two dimension orthogonal system


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3.1.2 (a,b) →(d,q) (the Park transformation)

Figure 8 Stator current space vector and its component in (a,b) and in the d,q rotating reference

frame

Figure 8 shows If we consider the d axis aligned with the rotor flux, for the current

vector, the

relationship from the two reference frame. θ is the rotor flux position. The flux and

torque components of the current vector are determined by the following equations:

These elements on the rotor flux vector (α,β) and current position. If we know the

correct flux position and then, with the design, d and q component become constants

3.1.3 (a,b) →(d,q) (inverse Park transformation)

Here, we introduce from this voltage transformation only the equation that modifies

the

voltages in d,q rotating reference frame in a two phase orthogonal system:

The outputs of this block are the components of the reference vector that we call

; is the voltage space vector to be applied to the motor phases.


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3.2 The basic scheme for the FOC

Figure 9 Basic scheme of FOC for AC-motor

Figure 10 motor control systems


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In all sorts of vector control methods, we use an indirect crucial. But only one control

method, the measurement and processing of motor rotor model parameter is the time

constant Lr/Rr (in turn bad estimation is module). If the motor is a permanent magnet

synchronous motor, structure diagram and the corresponding function will be very

similar, no longer need to turn bad estimation, flux command can be set to zero

(magnets have their own flux). This work is part of the algorithm for calculating the

voltage level: must convert volts and ampere. As in any modern power electronics

system, the motor control system by muscle (power converter) and the brain (SCM).

Driving power converter (known as inverter) is driven by three PWM output. In figure

9, it is easy to see a powerful way to a buffer 3 0-5 v into a signal, the logic of the

pulse signal 300V - 0, to exert motor terminal. Motor winding inductors played a

low-pass filter function: remove the carrier frequency, smooth current changes,

forming a sine wave, namely the PWM waveform.

Let us begin from a advanced CPU one motor drive system overall demand. The

vector control algorithm for calculating, and must be in 1 ~ 10 calculation speed

between 1ms (kHz to 100 mu s time, depending on the final closed-loop application

of bandwidth. System requires a lot of mathematics calculation (triangle function, PID

regulator, real-time flux and the torque motor parameter estimation based on). In

addition, must give the rest of the application (communication, the user interface, etc.)

of computing conservatives. In order not to limit dynamic performance, the main

control variables to the lowest 16, the precision of intermediate results need 32-bit

computing power.

3.3 The input for the FOC

Fundamental requirements for the FOC are a knowledge of two phase currents (as the

motor is star-connected, the third phase current is also known, since ia + ib + ic = 0 ),

and the rotor flux position.

3.3.1 current sampling

Measurement of three-phase current Ia and Ib, and a sampling A / D converter to

convert. FOC work correctly depends on the real current measurement.

3.3.2 Rotor flux position

Position of the rotor flux field oriented control of knowledge is the core. . In fact if


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there is an error in this variable the rotor flux is not aligned with d-axis and iSd and

iSq are incorrect flux and torque components of the stator current. The following

figure shows (a, b, c), (α, β) and (d, q) frame of reference, and the correct position the

rotor flux, stator current and stator voltage space vector rotating with d, q refer to the

synchronization Speed.

Figure 11 Current, voltage and rotor flux space vectors in the d,q rotating reference frame and

their relationship with a,b,c and α,β stationary reference frame

Measure the rotor flux position is different, if we consider the synchronous or

asynchronous motors.

Synchronous machine in various parts of the rotational speed is equal to the speed of

rotor flux. Then Q (rotor flux position) is directly measured by the position sensor or

rotor speed integration.

Induction machine in various parts of the rotor speed is not equal to the rotor flux

speed (with a sliding speed), it requires a special method to calculate the basic

question is the current model, the model equations requires two motors in the use of

D , q coordinate system.


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4. BACM current control modules

Figure 12 Block diagram of the BACM torque control

Once more the components placed within the framework of favor, is to control the

structure of software modules, hardware modules and their external side. The

software recognition module described above, these characters and their development,

which is the controller on the basis of functional requirements, as discussed below.

Brushless DC Motor Controller now submitted a request for discussion, but also for

BACM current controllers. Although there are differences, due to the current direction

control, which leads to more complex cases of BACM the current control structure

needs higher resolution. More specific needs of the mainstream carriers is divided into

two parts, one is the magnetization of the rotor torque production and a responsible,

both under dynamic conditions need to be considered a separate control of the

equivalent magnitude. The current control process once the motor current and to take

appropriate regulatory action, its specific need to set the value of monitoring

compared. Since this is to perform torque and magnetization, the current control logic

of the current control requires the implementation of appropriate mathematics, to

"convert" to their counterparts as well as magnetic torque and the stator current, and

vice versa, in order to fulfill its adjustment operation. This change is through the use

of forward Clark, reverse park the motor current controller of the feedback path and

forward Park, reversing a motor current controller direct path Clarke transformation.

The business needs to determine the necessary current controller (the official name of

the person with the torque control) to achieve the appropriate software modules. More

specifically, the following software modules need to be taken into account; ADC

initialization (for reading the user's set point and two-phase current motor use), more


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logical unity feedback control system (which is a unique, When the feedback is

negative, a summer feedback is positive, if in the power plant), compensator, reverse /

forward the changes Park and Clark, with the PWM unit interface logic and the PWM

unit initialization. Each of these software modules discussed in detail the following.

Such as ADC, more logical, compensation, interface logic and PWM initialization

discussed under the brushless DC motor of software modules and logic has not

changed, because they are even in the BACM software module, there is no need to

further negotiations. As for the case forward / reverse conversion Software Park and

Clark module, which by the appropriate command (program) through software

programs to achieve their mathematical equivalent transformation process.

Differences in sampling a current feedback is the fact that there is a consideration in

the BACM three current brushless DC motor in a single case against the current

monitoring (one for each phase) the need. However, because every time a balanced

three-phase systems (particularly true in the case of point, there is no connection

among other places), and currents into the system and is always zero (any current

value into the system, leaving the system), there is need to monitor only two or three a

current of. On the following formula can be derived from the value of the third

A successful derivation of the third current special consideration is to avoid any offset

in the sampling process, it is possible just by following the procedures for a complete

discussion (based on hardware sensor interface module and the ADC's offset program

in its initial zero software module).

The software module the following order: first, ADC sampling the user's set point and

two three motor currents. Second, the calculation of the third current and rotor

position readings. Once these software modules, thus completing their feed value

(three-phase current and rotor position) of the forward and reverse current of Clark 'in

transition, in the torque and the three-phase DC components of the extraction results

of combined experience of the current park software modules motor. The following

software modules is more, this is the implementation of the torque current component

and the user's set point, once more for the DC component of zero set point (the reason

for its implementation is in a lower note). Each of them in turn feed compensator

module (which again is executed twice). The output of the two modules to

compensation, feed forward and reverse park Clarke software modules to the

equivalent components into a three-phase direct torque and current commands.

Following Clark, the former parks and reverse scaling software modules into the logic

module output, so that the inside of the unit where the supply of PWM control cycle

3-phase voltage motors by summing up the equivalent scope of the inverter.


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The last one, more consideration is a voltage source inverter as the servo amplifier.

The reason is due to the fact that, when an inductive load such as motor () is fed by a

voltage source and load currents through this phase without applied voltage. Because

it appears from the above idea, the torque for the controller stage of the successful

implementation of current control and high accuracy. The whole process becomes

more complicated when the applied voltage changes the frequency is, as it is in a year,

itself and the corresponding result of changes in the current phase. To compensate for

this phase of the magnetization transfer (or direct) current adjustment control has been

added in the control structure, it is given a value of zero set point. In this way, the

control structure can compensate for the voltage and current between the phases

differences caused by, because it may take appropriate action to zero magnetization

current.

5. Design

Figure 13 the block diagram (a)


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The above figure show the block diagram of this project. According to above diagram

I can write some codes step by step.

6. Programming

6.1 S function model code

The following is code of S function model and comments which based on the rotor

field-oriented vector control system of ac motor

/////////////////////////////////////////////////////////////////////////////////////////////////

function[sys,x0,str,ts]=model_sfunc(t,x,u,flag)

/MODEL_SFUNC A M-file S-function for defining a system of inductor motor

model_parameter; /model_paramerer.m

A=K*[-Rs*Lr,w*Lm^2,Rr*Lm,w*Lm*Lr

w*Lm^2,-Rs*Lr,-w*Lm*Lr,Rr*Lm

Rs*Lm,-w*Lm*Ls,-Rr*Ls,-w*Lr*Ls

w*Lm*Ls,Rs*Lm,w*Lr*Ls,-Rr*Ls];

B=K*[Lr,0;0,Lr;-Lm,0;0,-Lm];

C=[1,0,0,0;0,1,0,0];

D=zeros(2,2);

Figure 14 the block diagram (b)

BF

DSP

PWM Unit Inverter Motor

A/D

Position

sensor

Torque set

reference

point

Memory

mapped SPI


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/

/dispatch the flag

/

switch flag,

case 0

[sys,x0,str,ts]=mdlInitializeSizes; / Initialization

case 1

sys=mdlDerivatives(t,x,u); /Calculate derivatives

case 3

sys=mdlOutputs(t,x,u); / Calculate outputs

case2,4,9

sys=[ ]; /Unused flags

otherwise

error(['Unhandled flag=',num2str(flag)]); /Error handling

end /end model_sfunc

/

/ mdlInitializeSizes

/ Return the sizes, initial conditions, and sample times for the S-function.

/

function [sys,x0,str,ts]=mdlInitializeSizes

sizes=simsizes;

sizes.NumContStates=5;

Sizes.NumDiscStates=0;

Sizes.NumOutputs=6;

Sizes.NumInputs=3;

Sizes.DirFeedthrough=1; /Matrix D is nonempty

Sizes.NumSampleTimes=1;

sys=simsizes(sizes);

x0=[ 1.800,6.530,-2.350,-0.970,600 ]; % initialize the initial conditions

str=[] ; /str is an empty matrix.

Ts=[0,0] / Initialize the array of sample times

/end mdlInitializeSizes

/

/ mdlDerivatives Return the derivatives for the continuous ststes.

/

function sys=mdlDerivatives(t,x,u)

Sys(1:4)=A*X(1:4)+B*u;

Te=np*Lm*(X(2)*X(3)-X(4)*X(1));

w=X(5);

Sys(5)=((Te-u(3))*np-D*X(5))/J;

/ end mdlDerivatives.

/


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/ mdlOutputs Return the block outputs

/

Function sys=mdlOutputs(t,x,u)

sys(1:2)=X(1:2);

sys(3)=Ls*X(1)+Lm*X(3);

sys(4)=Ls*X(2)+Lm*X(4);

sys(5)=X(5);

sys(6)=np*Lm*(X(2)*X(3)-X(4)*X(1));

/ end mdlOutputs.

[model_parameter.m]

Rs=0.687; / stator resistance(Ω)

Rr=0.642; / rotor resistance(Ω)

Ls=0.084; / stator inductance(H)

Lr=0.852; / rotor inductance(H)

Lm=0.813; / mutual inductance(h)

W=1400; / real speed(rpm)

Np=2; / pole number

J=0.3; / moment of inertia（kgmm）t

D=0.01; / torque damp coefficien

K=1/(Ls*Lr-Lm*Lm);

/end

//////////////////////////////////////////////////////////////////////////////////////////////////////

6.2 Main comments

The code of this project mainly is based on the following comments.

//declare global variable for the three phase currents, stationary reference current

variables, rotating frame reference current variables.

//You will need the following functions:

//Read_adc //This is for reading the current that goes in the motor,

three phase motor thus three phases curenents need to be acquired.

//Read_position //The mechanical position of the rotor is require for the

reverse/farward Park/Clark trhansformations...

// The following transformaitons are required to convert ac to dc for

controll operations and dc to ac to drive the motor.

//Forward Park

//Reverse Park


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//Farward Clark

//Reverse Clark

//PI_control

//Initialize adc, this is soing to be over SPI thus you will need to develope an

initialisation code for an SPI interface system.

//For now you will not have to warry about the PWM inverter as there is a need for a

memmory mapped peripheral... However you will

//need to develope code to access external memmory space

main( int argc, char *argv[] )

//Call the Initialize_adc_unit

//Call the PWM_unit_initialize

while(1)

//Call_read_adc //This is for reading currents and also the user's reference

commands.

//Call read_position

//Call the necessary Clark Park transformation READ TI PAPER

//Call PI_control

//Call the necessary oposit Clark Park transformation READ TI PAPER

//Call PWM_update

7. Results

The ideal results are three controls. It is Initialization process, Speed control and

Position Control.


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7.1 initialization process

Figure 15 current trajectories of vector control in initialization

<1>Control current increases until the state 1, I’=Ilimit, to prevent the sudden increase

of current caused by damage to the motor.

<2>When the current to book value, the keeping time until the state 2. Motor mover

parked in a particular fixed location, this location shall be q-axis. According to

equation motor mover power to the state

2 from the end of the trip passed δ, shall be converted into power perspectiveRequired

θ. State in the 1,2, θare zero.

<3>Mover of the stable in the state 2, gradually increasing angle θto angle θlimit

<4>θ angle to keep the state 4 to calculate the location of the current mover position

with the state 2, the difference. If negative, then the mover of the motion direction and

position signal counter is in the opposite direction, note 1, D = 1; if positive, the

moving direction and moving sub-position sensors are in the same direction, note D =

1. Convenient for the calculation, make the following change: D=1: θ0=90。

-θ0; D=-1:

θ0=θ0-90。


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<5><6>In turn will beθ, I’ decreases to zero. Thus, the initialization process is

completed.

7.2 speed control

Figure 16 Speed command, actual speed waveform

In the field oriented vector control based on the linear form of AC motor speed

control system, Figure 16 for the introduction of vector control the speed command

and speed response to a set of experimental curves. As can be seen from Figure 16,

step input, the motor speed can be a very good mover speed command tracking

response time of less than 1 ms.


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7.3 position control

Figure 17 waveform of position command, the actual location

Figure 17 for the introduction of closed-loop control of position, position instruction

and the position feedback waveform. Can be seen, the actual location of a good

tracking position instruction, small overshoot and can quickly stabilize.

The above analysis shows, this project method in the practical system can achieve

good vector control of AC linear motor.

8. Conclusion and further development

This report the most important chapter is field orientated control of 3-Phase AC-motor

and BACM current control modules. Asynchronism motor control system response

speed, torque smoothly. Most field-oriented control system uses this method, its

advantage is that the system realizes the decoupling control of flux and torque control

algorithm is simple; drawback is flux closed-loop control system the rotor flux

detection accuracy by the rotor time constant greatly influenced, to some extent

affected the performance of the system.


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Following a description of common major drawbacks of classic control structures it

has been shown how the Field Orientated Control overcomes these deficiencies and

what kind of benefits Field Orientated Controlled AC drives can bring. By explaining

in detail each of the FOC modules necessary this paper presents a clear introduction to

efficient vector control of AC drives.

Also this report is readable by related electronic professional readers.

8.1 Further development

The hardware should be added in this project. As some reasons hardware cannot

connect with software. The important further work is to connect with software. Thus

this project is base on software to control it.

Another point is AC linear motor vector control. AC permanent magnet linear

motor-driven movement system with high dynamic performance, however, permanent

magnet linear motor variables and multiple electromagnetic coupling between the

mechanical variables increases the difficulty of motion control. Although vector

control to address the issue of control of AC motor offers high performance principles

and methods, but how to apply it to real systems, especially the control of AC linear

motor, is still a problem to be studied


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9. Projection time plan

Figure 18 Project time plan


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10.References

[1] Brushless AC Motor Commutation

http://www.pmccorp.com/support/appnotes/an1004.pdf

[2] File:Pwm.png http://commons.wikimedia.org/wiki/File:Pwm.png

[3] A/D Board Tutorial

http://www.diamondsystems.com/slideshow.php3?name=ADBoardTutorial&page=2

[4] Analog-to-digital converter

http://en.wikipedia.org/wiki/Analog-to-digital_converter

[5] Field Orientated Control of 3-Phase AC-Motors

http://focus.ti.com.cn/cn/lit/an/bpra073/bpra073.pdf

[6] PID Controller Simplified

http://radhesh.wordpress.com/2008/05/11/pid-controller-simplified/

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Torque Control

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