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An-Najah National UniversityFaculty of Engineering

Electrical Engineering Department

Introduction in Graduation project

Variable speed control of single phase Induction motor

Prepared By: Ala' ‘Mohammad Radwan’ Saleh

Ala' Mohammad MareeSawsan Wahid Alhaj As'ad

Submitted To:Dr. Kamel Saleh

Contents

Results.

H-Bridge Inverter.

VF Control.

Principle of Operation of Induction Motor.

Future Work.

Modelling of Single Phase Induction Motor

Variable Speed Control of Single Phase Induction Motor

• To make simulation includes modelling of single phase induction motor, H-bridge inverter, PWM generator, and presenting the experimental results.

• To build a variable speed drive of the single phase induction motor using frequency control method.

Objectives

Principle of Operation of Induction Motor

• In principle of operation of induction motor, rotating magnetic field rotates at synchronous speed interacts with rotor , this will produce torque that will make the rotor rotates at mechanical speed.

• In three-phase induction motor, the rotating magnetic field is generated by applying three currents shifted by 120 degrees to three windings also shifted by 120 degrees.

• In single-phase induction motor, there are many types based on method of starting, these types are:

Principle of Operation of Induction Motor

Split-phase induction motor.

Capacitor start induction motor.

Permanent-split capacitor motor.

Capacitor start capacitor run motor.

1

2

4

33In this type the auxiliary winding and the capacitor are connected from the motor after starting

In this type two capacitors are used with the auxiliary winding, one for starting and the other during start and run.

• In most of these types the rotating magnetic field is generated by applying two currents shifted by some angle(using capacitor) to main and auxiliary windings.

• In our project, the rotating magnetic field is produced by applying two currents shifted by 90 degrees exactly to auxiliary and main windings using inverter. This two currents are shifted without using capacitor. So we can use any of previous types but without capacitor.

Principle of Operation of Induction Motor

Modelling of Single Phase Induction Motor

• Single-phase induction motors with main and auxiliary winding can be viewed as two-phase machines.

• Therefore, two-phase induction motors have a configuration identical to single-phase induction motors, but a two-phase voltage is supplied to the stator windings terminal.

So, modeling of single phase induction motor can be done as the following:

Mathematical Model

Equivalent circuit of two phase induction motor.

Mathematical Model

Mathematical Model

Modeling Using Matlab/Simulink

Model of induction motor.

H-Bridge Inverter

H-bride inverter is used to control the direction of rotation of induction motor. The following figure shows the H-bridge inverter.

To feed H-bridge inverter by four pulses signal, PWM technique was used.

H-Bridge inverter.

PWM Technique

In PWM technique, an input analog signal (carrier signal) and a saw tooth waveform (modulating signal) are driven in a comparator. Each time saw tooth waveform voltage is less than the input signal, the PWM output is driven high and vice-versa.

The following Figure shows the PWM technique.

PWM Technique.

PWM Technique

PWM technique was simulated using Matlap/Simulink as shown in the following figure.

PWM generator using Matlap/Simulink.

PWM Technique

The H-bridge inverter and the PWM generator were connected as shown in the following figure.

PWM generator+ H-bridge inverter.

The following figure shows the output of PWM generator and H-bridge inverter a reference speed of 1000r.p.m was interred to PWM generator.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.5

1

Time(s)

V(v

olt)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.5

1

Time(s)

V(v

olt)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.5

1

Time(s)

V(v

olt)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.5

1

Time(s)

V(v

olt)

PWM0, PWM1, PWM2, and PWM3 signals.

PWM Technique

PWM Technique

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-300

-200

-100

0

100

200

300

Time(s)

Vs-a

lfa(v

olt)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-300

-200

-100

0

100

200

300

Time(s)

Vs-b

eta(

volt)

Outputs of H-bridge inverter.

The PWM generator and the H-bridge inverter were connected to the induction motor model as shown in the following figure.

Model of variable speed control of single phase induction motor.

PWM Technique

VF Control

VF Control

Results

0 1 2 3 4 5 6 7 8 9 10-500

0

500

1000

1500

2000

2500

Time(s)

Spe

ed(r

.p.m

)

is-alfa

is-beta

WmWref

1.9 1.95 2 2.05 2.1 2.15 2.2-50

-40

-30

-20

-10

0

10

20

30

Time(s)

Cur

rent

(A)

Is-alfa

Is-beta

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.050

0.5

1

Time(s)

V(v

olt)

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.050

0.5

1

Time(s)

V(v

olt)

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.050

0.5

1

Time(s)

V(v

olt)

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.050

0.5

1

Time(s)

V(v

olt)

Is-alfa

Is-beta

Outputs of PWM generator (PWM0, PWM1, PWM2 and PWM3).

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05-300

-200

-100

0

100

200

300

Time(s)

Vs-

alf

a(vo

lt)

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05-300

-200

-100

0

100

200

300

Time(s)

Vs-

be

ta(v

olt)

Is-alfa

Is-beta

• Second Test

The reference speed is a step with: step time = 2s, initial value = 0 and final value = 2000r.p.m, with a step load (step time = 1s, initial value = 0 and final value = 10N.m).

The following figure shows the measured speed.

0 1 2 3 4 5 6 7 8 9 10-500

0

500

1000

1500

2000

Time(s)

Spe

ed(

r.p

.m)

Is-alfa

Is-beta

WmWref

0 1 2 3 4 5 6 7 8 9 10-500

0

500

1000

1500

2000

2500

3000

3500

Time(s)

Spe

ed(r

.p.m

)

Is-alfa

Is-beta

Wref

Wm

• Fourth Test

The reference speed is a step with: step time = 2s, initial value = 0 and final value = 3000r.p.m, with a step load (step time = 3s, initial value = 0 and final value = 5N.m).

The following figure shows the measured speed.

0 1 2 3 4 5 6 7 8 9 10-500

0

500

1000

1500

2000

2500

3000

Time(s)

Spe

ed(r

.p.m

)

Is-alfa

Is-beta

Wref

Wm

0 2 4 6 8 10 12-500

0

500

1000

1500

2000

2500

3000

Tme(s)

Spe

ed(r

.p.m

)

Is-alfa

Is-beta

WmWref

1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5-50

-40

-30

-20

-10

0

10

20

30

Time(s)

Cur

rent

(A)

Wm

Wref

is-beta

is-alfa

Future Work

The following figure shows how the project will be built.

Single phase induction motor drive with H-bridge inverter.

The following figure shows the data sheet of PIC16F877 microchip which will be used to generate the PWM signals needed. Pin 16 and pin 17 are the pins that generate PWMs.

Data sheet of PIC16F877

Future Work

Future Work

The following figure shows the typical connection of gate drive, which will be used to convert the voltage from 0-5V to 0-15V.

Typical connection of the gate drive.

Future Work

Reference SpeedReference Speed 0-5V0-5V 0-15V0-15V -300-300V-300-300V

PIC16F877

MicrochipGate Drive

H-Bridge Inverter

Induction Motor