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Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki 1
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Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Dec 22, 2015

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Page 1: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Prepared by: Luis Fernando Montoya

Chun-Ju HuangAshish K. Solanki

1

Page 2: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Introduction Applications of AC drives Types of Methods to control the speed of Induction machine V/F controlPower ConvertersSimulation ModelSimulation Results Conclusion Reference

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Page 3: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

An electric drive system consisting of electric motor, its power controller and energy transmitting shaft consisting of load

Types of Drive system (1)DC Drive(2)AC Drive AC Drives are mostly used in Industry.

Introduction

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Page 4: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Advantages and disadvantages of AC Drives compare to DC Drives

Advantages of ac drives 1. For the same rating, ac motors are lighter in weight as compared

to dc motors.2. AC motors require low maintenance.3. AC motors are less expensive.4. AC motors can work in dangerous areas like chemical,

petrochemical etc. Disadvantage of ac drives1.Power converters for the control of ac motors are more complex.2.Power converter for ac drives are more expensive.3.Power converters for ac drives generate harmonics in the supply

system and load circuit. 4

Page 5: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Industrial applicationsInduction motors with squirrel cage rotors are the workhorse of

industry because of their low cost and rugged construction.When Squirrel cage induction machine is operated directly from

the line voltages(60 Hz/50 Hz essentially constant voltage) an Induction motor is operated at constant speed. However in the industry we required to vary the speed of an Induction motor. This can be done by Induction motor drives.

Main application of Induction Motor drives: Fans, Compressor, Pumps, blowers, machine tools like lathe,

drilling machine, lifts, conveyer belts etc.

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Page 6: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Methods of Speed Control of Induction motors

(1) Stator voltage Control (2) Stator Frequency Control (3) Stator Current Control(4) V/F Control (5) Slip power recovery Control ( Wound Rotor Induction

Machine)

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Page 7: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Curve of the behavior of the Induction Machine

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• During start up. Normally draws up to seven times the rated current.

• Normally delivers approximately 1.5 the rated torque, when starting

• When operating at base speed if the load is increased, the motor will start slowing down and the slip will increase.

•But if the load is increased beyond the Break down torque, the machine wont be able to recover.

Page 8: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

V/Hz Theory BackgroundThe induction motor

draws the rated current and delivers the rated torque at the base speed.

As mentioned before the motor can take up to 2.5 load increase, with 20% drop in the speed.

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Page 9: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Description of the principle

Assume the voltage applied to the Motor is AC, and the voltage drop across the Armature resistance very small. Then at the steady state we get:

(Voltage applied at the stator, and Flux)

Since the V/f relation keeps constant, then the flux remains constant and the torque is independent of the supplied frequency.

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Page 10: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Description of the PrincipleSince the flux is maintained

constant, the toque developed depends only on the slip speed.

Huge starting torque can be obtained without heating-up the machine

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Page 11: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

V/Hz Open Loop

11

Torque

Synchronousfrequency

Page 12: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

V/Hz control Closed loop

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Page 13: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Three Phase Full Bride Uncontrolled Rectifier

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Page 14: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

DC-DC Boost Converter

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Page 15: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

DC-DC Boost Converter

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Page 16: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

3 Phase PWM Inverter

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Page 17: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Block Diagram of Simulation Model

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Page 18: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation Model

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Page 19: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Uncontrolled Rectifier and DC-DC Boost Converter Simulation Model

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Page 20: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

3 phase inverter with Squirrel Cage Induction Motor

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Page 21: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsInput Voltage for 3 phase uncontrolled Rectifier

4.14 4.145 4.15 4.155 4.16 4.165 4.17 4.175

-400

-300

-200

-100

0

100

200

300

Time(s)

Inpu

t V

olta

ge t

o re

ctifi

er(V

)

Voltage input to rectifier

Vin A

Vin BVin C

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Page 22: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsOutput Voltage of three phase uncontrolled rectifier

0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24

-300

-200

-100

0

100

200

300

Time(s)

Out

put

Voltage o

f R

ectif

ier(

V)

Vin A

Vin B

Vin C

Rectified Output voltage

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Page 23: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsOutput Voltage of DC/DC Boost converter

0 2 4 6 8 10 12 14 16 18 200

50

100

150

200

250

300

350

400

Time(s)

Out

put V

olta

ge o

f DC

DC C

onve

rter(V

)

Output Voltage of DC DC Converter

Vdc out

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Page 24: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsOutput Voltage of 3 Phase PWM inverter before filter

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5-500

0

500

Time(s)Voltag

e Outp

ut inv

erter(

V))

Output Voltage of Inverter before filter

Vout inv A

Vout inv BVout inv C

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5-500

0

500

Time(s)

Voltag

e Outp

ut inv

erter

phase

A(V))

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5-500

0

500

Time(s)

Voltag

e Outp

ut inv

erter

phase

B(V))

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5-500

0

500

Time(s)

Voltag

e Outp

ut inv

erter

phase

C(V))

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Page 25: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsOutput Voltage of Inverter after filter

( Controlled Input voltage given to Induction motor)

0 2 4 6 8 10 12 14 16 18 20-250

-200

-150

-100

-50

0

50

100

150

200

250

Time(s)

Vol

tage

Inpu

t to

Mac

hine

(V)

Output Voltage of Inverter after filter(input Voltage to Machine)

Vin m A

Vin m BVin m C

3.68 3.7 3.72 3.74 3.76 3.78 3.8 3.82 3.84 3.86 3.88

-200

-150

-100

-50

0

50

100

150

200

Time(s)

Voltage I

nput

to M

achin

e(V

)

Output Voltage of Inverter after filter(input Voltage to Machine)

Vin m A

Vin m B

Vin m C

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Page 26: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsStator Current

3.55 3.6 3.65 3.7 3.75 3.8 3.85 3.9

-10

-8

-6

-4

-2

0

2

4

6

8

10

Time(s)

Sta

tor

Curr

ent(

A)

Stator Current

Istator A

Istator BIstator C

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Page 27: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsRotor Reference speed and Actual Speed

Here the reference speed is 1000 rpm= 104.72 rad/sec

0 2 4 6 8 10 12 14 16 18 20-20

0

20

40

60

80

100

120

Time(s)

Roto

r S

peed (

rad/s

ec)

Rotor Speed

Reference Speed

Actual Speed

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Page 28: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsWithout Filter after the PWM inverter , rotor speed is fluctuating

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Page 29: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Simulation ResultsRotor Reference speed and Actual Speed

0 2 4 6 8 10 12 14-10

0

10

20

30

40

50

60

70

80

90

100

Time(s)

Roto

r S

peed (

rad/s

ec)

Rotor Speed

Reference Speed

Actual Speed

0 2 4 6 8 10 12 14 16 18 20-20

0

20

40

60

80

100

120

140

Time(s)

Roto

r S

peed (

rad/s

ec)

Rotor Speed

Reference Speed

Actual Speed

0 2 4 6 8 10 12 14 16 18 20-20

0

20

40

60

80

100

120

140

160

180

Time(s)

Roto

r S

peed (

rad/s

ec)

Rotor Speed

Reference Speed

Actual Speed

Reference speed is 1300 rpm=136.14 rad/sec

Reference speed is 600rpm= 62.83 rad/sec

Reference speed is 1500rpm= 157.08 rad/sec

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Page 30: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Rotor Reference speed and Actual Speed

Reference Speed is changed from 104.71 rad/sec to 92.24 rad/sec

0 2 4 6 8 10 12 14 16 18 20-20

0

20

40

60

80

100

120

Time(s)

Roto

r S

peed (

rad/s

ec)

Rotor Speed

Reference Speed

Actual Speed

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Page 31: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

ConclusionIn Case of Squirrel cage induction motor the slip

cannot be increase above certain limit, the operating speed range is very less. By applying the V/F control we can get the large operating range by keeping V/F ratio constant.

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Page 32: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

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Page 33: Prepared by: Luis Fernando Montoya Chun-Ju Huang Ashish K. Solanki Speed control of squirrel cage induction machine using V/F control 1.

Reference[1] Modern Power Electronics and AC drives by Bose, Bimal K. [2] POWER ELECTRONICS Converters, Applications and Design

by Ned Mohan[3] Power electronics Lecture Notes by Prof. Nasiri[4] Lecture Notes by Dr. Omar[5] AC Induction Motor Control using Constant V/Hz Principe

and Space Vector PWM Technique with TMS320 C240[6] Speed Control of 3-Phase Induction Motor Using PIC18

Microcontrollers

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