SPEED CONTROL OF SINGLE PHASE INDUCTION MOTOR BY

PWM TECHNIQUE USING LABVIEW

A.Manikandan1, M.Naveen

2, P.Prakash

3

U.G. Students, Department of EEE, Mahendra Engineering College, Namakkal.

Dr.S.Umamaheshwari4, Prof/Dept of EEE, Mahendra Engineering College, Namakkal

B.S.Rajan5, Assistant Professor, Department of EEE, Mahendra Engineering College,

Namakkal

ABSTRACT:

This proposed system is to control the

speed of single phase induction motor by

PWM technique. This technique has high

efficiency to drive an induction motor

using pulse width modulation technique

(PWM) and is designed for minimal cost.

The circuit is controlled by using

LabVIEW Software with Arduino (Atmel

328) controller. The reason of using

LabVIEW domain is of its strong

interface, simplicity of its Graphical

Programming Code combined with built in

tools designed especially for testing,

measuring and controlling. With PWM

technique it is competent of supplying

high frequency to run the induction motor

at accurate speed. Through DAQ the signal

is acquired and the system is controlled.

KEYWORD: Atmel328 controller,

Optocoupler, Induction motor, LabVIEW,

DAQ.

I. INTRODUCTION

Induction motors are widely used in

industrial and commercial utility

applications. It gained momentum because

of its high efficiency and various speed

ranges. Compare to DC machines, AC

machines are mostly used in variety of

applications due to their simplicity and

low cost. Motor control applications span

everything from residential washing

machine, fans, traction control system and

various industrial drives. LabVIEW is a

graphical programming code for data

acquisition, analysis, and presentation. The

components of LabVIEW are front panel

and block diagram. Front panel is used to

build controls and indicators and block

diagram contains pictorial representation

of code. In this work LabVIEW based

control is designed to control the speed of

induction motor using PWM technique.

Dynamic characteristics of electrical

machines are learnt using simulation tools

available in LabVIEW. Usage of virtual

instrumentation software to analyze and

control is not only subjected to cost

reduction but also gives enhanced

performance.

II.BLOCK DIAGRAM

Fig.1 Block diagram of Proposed System

The system existing is similar as that of

speed control using voltage control method

in which voltage is varying from zero to

maximum value. Here Pulse width

modulation technique to control the speed

of induction motor is proposed which

produces the lower order harmonics. In the

Figure 1, the PWM controlled MOSFET is

connected in series with bridge rectifier

and the input of bridge rectifier is

connected in series with load and the

output terminal is connected across power

transistors. Initially its known fact that

current cannot flow through the open

circuit therefore power transistor is in OFF

state. If the bridge rectifier circuit is short

circuited, the power transistor gets

switched ON and current flows through the

rectifier to load. The power to the load is

controlled by changing the duty cycles of

PWM pulses. The pulses are synchronized

with supply phase by zero sensing point.

III.HARDWARE SYSTEM

a) LABVIEW

LabVIEW programs are called virtual

instrumentation (VI) because their

appearance and operation imitate physical

instruments, such as oscilloscopes and

Multi Meters. LabVIEW is a graphical

programming code used to acquire, control

and store data. It is possible to

communicate with hardware by using

DAQ, RS232 interface. Whenever the

serial port is ready to transmit data, it

fetches data to hardware buffer. The

controller receives data through the

interfacing devices and the motor is

controlled by changing the pulse width

modulation.

b) ATMEL 328

The high-performance, low-power Atmel

8-bit AVR RISC-based microcontroller

combines 16KB ISP flash memory, 1KB

SRAM, 512B EEPROM, an 8-channel/10-

bit A/D converter (TQFP and QFN/MLF),

and debug WIRE for on-chip debugging.

The device supports a throughput of 20

ATMEL

328

Controller

MIPS at 20 MHz and operates between

2.7-5.5 volts. By executing powerful

instructions in a single clock cycle, the

device achieves throughputs approaching 1

MIPS per MHz, balancing power

consumption and processing speed.

c) OPTO-COUPLERS

Opto-couplers are made up of a light

emitting device, and a light sensitive

device, all wrapped up in one package, but

with no electrical connection between the

two, just a beam of light. The light emitter

is nearly always an LED. The light

sensitive device may be a photodiode,

phototransistor, or more esoteric devices

such as Thyristors, TRIACs etc.

A lot of electronic equipment nowadays is

using opto coupler in the circuit. An opt

coupler or sometimes refer to as opt

isolator allows two circuits to exchange

signals yet remain electrically isolated.

This is usually accomplished by using

light to relay the signal. The standard opt

coupler circuits design uses a LED shining

on a phototransistor-usually it is an NPN

transistor and not PnP. The signal is

applied to the LED, which then shines on

the transistor in the IC.

Most commonly used is an opto-coupler

MOC3021 an LED Diac type combination.

This IC is interfaced with a

microcontroller and an LED is connected

in series to the IC, which glows to indicate

a logic High pulse from the

microcontroller so that we can know that

current is flowing in internal LED of the

opto-IC. When logic high is given current

flows through LED from pin1 to 2. So in

this process LED light falls on DIAC

causing 6 & 4 to close. During each half

cycle current flows through gate, series

resistor and through opto-diac for the main

Thyristors / triac to trigger for the load to

operate.

d) SOLID STATE RELAY (SSR)

Fig.2 Circuit diagram for SSR

SSR stands for Solid State Relay. SSRs

have no movable contacts. SSRs are not

very different in operation from

mechanical relays that have movable

contacts. SSRs, however, employ

semiconductor switching elements, such as

thyristors, triacs, diodes, and transistors.

Furthermore, SSRs employ optical

semiconductors called photo-couplers to

isolate input and output signals.

Photocouplers change electric signals into

optical signals and relay the signals

through space, thus fully isolating the

input and output sections while relaying

the signals at high speed. SSRs consist of

electronic parts with no mechanical

contacts.

IV. SIMULATION RESULT

Figure 4 indicates the front panel of

LabVIEW in running condition of the

induction motor. Variation of speed with

respect to time controlled by PWM

techniques is shown in Figure 5. It clearly

shows that the speed of the motor attains

the rated speed within the short duration

and it tabulated in the Table 1.

Fig.4 Front panel at running condition

Table1. Speed Vs Time

V. GRAPHICAL RESULTS

A) PROPOSED SYSTEM

Fig.5 Graphical representation of user

speed control with respect to time

Fig.6 Graphical representation of PWM

wave

Speed

(rpm)

Time

(ms)

Frequency

(UHZ)

1000 10 36

2000 20 73

3000 30 108

4000 40 145

5000 50 185

CONCLUSION

LabVIEW based speed control of single

phase induction motor using pulse width

modulation technique is seems to be more

31% more efficient when compare with

existing system. The accurate speed can be

achieved by using this technique. By using

this technique user can control the speed of

induction motor according to the

requirements.

REFERENCES

[1]. Shilpa V. Kailaswar Prof.

R.A.Keswani/International journal of

Engineering Research and application

(IJERA),PP, 1732-1736. Speed control of

three induction motor by V/F method for

batching motion system.

[2]. S .M. Wankhede, R.M. Holmukhe,

miss A.M. Kadam. Miss P.R. Shinde, P.S.

Chaudhari. Microcontroller Based Control

of three phase induction motor using

PWM technique.

[3]. Application Note-017, PWM Motor

Drives-Theory and Measurements

Considerations.

[4]. The 8052 Microcontroller and

Embedded system Pearson Education-

M.A.Mazidi.