operating three phase induction motor connected to single phase

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 11, November 2012)

523

Operating Three Phase Induction Motor Connected to Single

Phase Supply Shivanagouda.B.Patil

1, M. S. Aspalli

2

1,2 Department of Electrical and Electronics Engineering, P.D.A.C.E, Gulbarga, Karnataka, India

Abstract – This paper presents a simple converter

topology for driving a three-phase induction motor with a

single-phase ac supply. Using only two active switches and a

Triac, the converter can start the motor with high starting

torque and low input current, and run the motor at rated

speed. The converter supplies balanced output voltages at

rated frequency, the proposed control approaches are

supported by test results. In the proposed scheme,

dsPIC30F2010 controller is used to produce PWM signals.

A 3-phase, 415V, 1440RPM, 1.5HP Induction motor is used

as load for testing the developed hardware. Textronics

TDS2024B storage oscilloscope is used to store the gate

pulses and waveforms. The experimental result showed that

PWM pulses produced remained approximately constant

with increase in load and the developed hardware has

satisfactory converted the single phase power to three phase

power.

Keywords – Single phase to Three phase, TRIAC, IGBTs,

Induction Motor, Split Capacitor

I. INTRODUCTION

Motor drives constitute a predominant load for the

agricultural sector. As most rural communities in the

India are supplied with single-phase ac power, these

drives have to be realized with single-phase motors, or

with three phase motors (Induction Motors) driven by

phase converters. Autotransformer capacitor phase

converters and rotary phase converters have been used

for several decades [1].Both have the advantages of

simple structure and reasonably low cost.

Autotransformer capacitor phase converters, however,

cannot easily obtain balanced output voltage with

reasonable cost, and rotary converters are heavy and have

significant no-load losses, also both topologies have high

inrush current during motor startup [2]. The three-phase

induction motors have some advantages in the machine

efficiency, power factor, and torque ripples compared to

their single-phase counterparts [3]. Though the precise

control of single phase induction motor is less complex in

comparison to the three phase induction motor, but when

the torque requirement is considered then three phase

induction motor is the best choice. The applications for

these motors cover almost every stage of manufacturing

and processing. It is not surprising to find that among all

type of electric motors, Induction motor is so popular,

when one considers its simplicity, reliability, and low

cost.

Therefore, it is desirable to replace the single-phase

induction motor drives by the three-phase induction

motor drives in some low-power industrial applications

[4] and [5]. However, in some rural areas where only a

single-phase utility is available, we should convert a

single-phase to a three-phase supply. This paper proposes

an alternative solution for phase conversion with very

low overall cost, moderate motor performance during

start up and high steady-state performance at line

frequency. This system fits the requirements in rural

areas where only a single-phase supply is available. This

paper describes the conversion of 1-phase power supply

to 3-phase and driving 3-phase AC induction motor using

16 bit High Performance Digital Signal Controller. The

dsPIC30F2010 devices contain extensive Digital Signal

Processor (DSP) functionality with high performance 16-

bit microcontroller (MCU) architecture.

The use of this 16-bit Digital Signal Controllers yields

enhanced operations, fewer system components, lower

system cost and increased efficiency. The system is

designed for driving medium power (1.5hp), 3-phase AC

induction motors. Our work consists of a half-bridge

rectifier, a split-capacitor dc bus, two active

devices(IGBTs) realizing the inverter section for

regulating the motor current and a TRIAC for controlling

the motor current.

The developed hardware is tested on a 3-phase, 415V,

50Hz Induction motor. According to the requirement, a

software program is written and is fed to the digital

signal controller (dsPIC30F2010) for the necessary

action. The inverter output current is regulated by a sine

wave reference, generated by software, and the TRIAC is

triggered at constant delay angle. The various

graphs/waveforms are analyzed and studied on Digital

Storage Oscilloscope.

II. BLOCK DIAGRAM AND ITS EXPLANATION

A. System overview

The block diagram of the proposed single phase to

three phase power conversion and driving three phase

induction motor is shown in figure 1.

It has half bridge rectifier and split capacitor, half

bridge inverter, Triac circuit, control circuit. In the

proposed work, the half bridge rectifier consists has 4-

6A-100L. In leg having two diode sets (upper and lower).



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Each set has two diodes connected in parallel to

increase/double current rating. The output of the rectifier

is filtered by using two 1000µF, 450V capacitors which

acts as split capacitor.

The half bridge inverter has 2-FGA25N120ANTD-

IGBT’s switches. The triac used is TO-220AB (BTB16-

800) with the snubber circuit to meet the requirement.

The output of half bridge rectifier with split capacitor,

half bridge inverter and triac is applied to the three phase

induction motor. A digital signal controller

(dsPIC30F2010) is used to implement the core of the

control function, which simplifies the hardware setup.

Fig1. Block diagram of the proposed system

B. Power circuit design

The power circuit designed contains half bridge

rectifier with split capacitors assembly, half bridge

inverter assembly and Triac assembly. At the start of the

motor it experiences a very high current and the motor

may not run at the rated speed. An electromagnetic relay

is used in the proposed scheme. Starting current of the

induction motor is six times that of the rated current for a

duration of 4 Seconds. To limit this heavy current flow,

two wire wound resistances of 50Ω, 10W each are

connected in parallel to the input supply. A single pole

change over relay is used to insert these wire wound

resistors for a period of 4secs and then the relay bypasses

these resistors for the rest of the operation.

F ig2. Half bridge rectifier and half bridge inverter

Single phase 230V, 50Hz AC supply is applied to the

half bridge rectifier and Triac via starter assembly. Triac

switches are protected against surge voltages using

snubber circuit. This half bridge rectifier converts single

phase AC input into DC which is filtered by two split

capacitors. The pure DC supply is applied to the half

bridge inverter which is made up of two IGBT switches.

The 3-phase induction motor is connected to half bridge

rectifier with split capacitors, half bridge inverter and

Triac as shown in figure 1. The half bridge with split

capacitors and half bridge inverter is shown in figure 2.

The energy that a switching power converter delivers to a

motor is controlled by Pulse Width Modulated (PWM)

signals applied to the gates of the switches. PWM signals

are pulse trains with fixed frequency and magnitude and

variable pulse width.

C. Control circuit

The control circuit of the proposed scheme consists of

a Digital signal Controller dsPIC30F2010.A Digital

Signal Controller (DSC) is a single-chip, embedded

controller that seamlessly integrates the control attributes

of a Microcontroller (MCU) with the computation and

throughput capabilities of a Digital Signal Processor

(DSP) in a single core. The dsPIC DSC has the “heart” of

a 16-bit MCU with robust peripherals and fast interrupt

handling capability and the “brain” of a DSP that

manages high computation activities, creating the

optimum single-chip solution for embedded system

designs. The dsPIC30F devices contain extensive Digital

Signal Processor (DSP) functionality within high-

performance 16-bit microcontroller (MCU) architecture.

It also consists of two opto-coupler for isolating the

control and power circuits. In this work an optocoupler

PC817 is used to isolate the gate drive circuit and the

IGBT-based power circuit. Two IGBTs of the power

circuit are controlled by the PWM signals generated by

the control circuit. MOC-3021 optoisolator is used for

triggering the Triac.



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III. EXPERIMENTAL SETUP AND ITS RESULTS

The conversion from single phase to three phase is

done successfully and the developed hardware is tested

with load. The proposed control system is implemented

by a DSC (dsPIC30F2010) based PWM inverter. C

language is used to develop the program. The device is

programmed using MPLAB Integrated Development

Environment (IDE) tool. It is a free, integrated toolset for

the development of embedded applications employing

Microchip's PIC and dsPIC controllers. For execution of

C-code, MPLAB compiler is used. In this work, I have

used 415V, 50Hz, 3-Ph, 1.5 HP Induction motor.

The hardware set is developed and tested in power

electronics laboratory and the photograph of complete

setup is shown in fig 3. The test is carried out on

induction motor for different loads and voltages. For

different loads and voltages, current drawn by the motor

and voltages across all lines are noted and are tabulated.

In the complete experiment the oscilloscope used is

Tektronix TDS2024B Digital Storage Oscilloscope

(DSO) to store gate pulses and voltage waveforms. The

speed of the induction motor is 1410 RPM, At particular

RPM, load is varied from 1KG to 4KG and

corresponding voltages and currents are noted.

Table 3.2, 3.4, 3.6 shows the output for variable

voltages and variable loads, corresponding waveforms

are taken from the DSO and are shown in figs 3.4 to 3.14.

The gate pulses are observed for different loads and

voltages are shown in the figs 3.1, 3.2, 3.3.

3.1 Experimental Result for the Input Voltage 110V,

50Hz

Table 1

Experimental Result for the Input Voltage 110V, 50Hz


50Hz

Table 2


Sl.

No.

Load Input

Voltage

Volts

Output Voltage

Volts

Stator

Current

Amperes

VA VB VC

1 0.5kg 140 181 178 188 0.62

2 1 kg 140 179 181 186 0.63

3 1.5 kg 140 173 183 188 0.64

4 2.0 kg 140 181 178 186 0.64

5 2.5 kg 140 181 178 186 0.7

6 3.0 kg 140 183 183 186 0.75

7 3.5 kg 140 181 183 186 0.8

8 4.0 kg 140 187 181 189 0.85


50Hz

Table3


Sl.

No.

Load Inpu

t

Volt

age

Volts

Output

Voltage Volts

Stator Current

Amperes

VA VB VC

1 0.5kg 180 22

8

22

9

23

1

0.62

2 1 kg 180 22

7

23

1

23

3

0.65

3 1.5

kg

180 22

7

22

9

23

1

0.7

4 2.0

kg

180 23

0

23

1

22

9

0.7

5 2.5

kg

180 22

8

23

1

23

4

0.75

6 3.0

kg

180 23

1

22

8

22

9

0.83

7 3.5

kg

180 23

3

22

7

23

0

0.9

8 4.0

kg

180 23

1

23

1

23

3

0.95

Sl.

No.

Load Input

Voltage

Volts

Output Voltage

Volts

Stator

Current

Amperes

VA VB VC

1 0.5kg 110 133 130 136 0.6

2 1 kg 110 131 131 134 0.63

3 1.5 kg 110 131 129 133 0.63

4 2.0 kg 110 133 136 134 0.63

5 2.5 kg 110 136 134 138 0.66

6 3.0 kg 110 138 134 137 0.75

7 3.5 kg 110 136 136 139 0.9

8 4.0 kg 110 138 133 138 0.92



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The gate pulses are observed for different loads and

voltages are shown in the following figs.

Fig 3.1 Gate pulse at 1kg



Fig 3.4 waveform across three lines

Fig 3.5 split capacitor waveform at 1kg

Fig 3.6 Traic waveform at 1kg


Fig 3.8 waveform across three lines



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Fig 3.9 split capacitor waveform a 2kg

Fig 3.10 waveform across inveter at 2kg


Fig 3.12 waveform across inverter 3kg

Fig 3.13 split capacitor waveform at 4kg

Fig 3.14 waveform across three lines at 4kg

Fig4. photograph of complete Experimental setup

IV. CONCLUSION

Three phase asynchronous induction motors are

widely used in industrial applications due to their

features of low cost, high reliability and less

maintenance. Due to the need for three-phase electricity

in today's remote areas for agriculture work where three

phase power is not available easily, in those areas these

single phase to three phase converters are use full.



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Operating a three phase induction motor using single

phase supply has been presented. The developed single

phase to three phase conversion hardware setup is tested

on a three phase 1.5hp, 415V, 50Hz induction motor with

loading in power electronics laboratory. From the

experimental setup and results chapter it is clear that the

developed hardware satisfactory converts from single

phase power to three phase power.

The developed system is useful in remote areas where

three phase supply is not available easily.

Applications of single phase to three phase converter

are:

In Irrigation Pumps for Agriculture purpose.

Rural Area Water Supply.

APPENDIX

The following defines the nomenclature and system

parameters used in this paper :

A. Molar parameters and nomenclature :

50Hz, 415V, 1.5hp, 3-phase, 4-pole induction machine.

B. Inverter parameters :

Vin : lnput voltage 230V

C1, C2 : DC bus capacitors 1000µ , 250V each

Q1,Q2: IGBTs FGA25N120ANTD 1200V, 25A

REFERENCES

[1 ] C. Hertz, “Current techniques in phase conversion systems,”

IEEE Rural Electric Power Con$ Rec., pp. 3549, 1978.J.

[2 ] J. Nesbitt et al., “A novel single phase to three phase converter,”

IEEE APEC Con$ Rec., pp. 95-99, 1991.

[3 ] P. N. Enjeti et al., “Economic single phase to three phase

converter topologies for fixed frequency output,” IEEE APEC

Con$ Rec., pp. 88-94, 1991. [4 ] C. Chen et ab, “A single phase to three phase power converter for

motor drive applications,” IEEE IAS Con$ Rec., pp. 639-646, 1992.

[5 ] P. N. Enjeti and A. Rahman, “A new single-phase to three-phase converter with active input current shaping for low cost ac motor

drives,”IEEE Trans. Ind. Applicar., vol. 29, no. 4, pp. 80C813 July/Aug. 1993.

[6 ] Chingchi Chen, “A Hybrid Inverter/cylcoconverter-Based

Variable-Speed Three-phase Induction Motor Drive for Single-phase Inputs” IEEE Tran. on Industry

application,Vol.31.no.3,may/june 1995

operating three phase induction motor connected to single phase

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