ENERGY EFFICIENT VARIABLE SPEED HIGH POWER FACTOR THREE PHASE INDUCTION MOTOR DRIVE USING COMBINED P

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Journal for Research| Volume 02 | Issue 06 | August 2016 ISSN: 2395-7549

Energy Efficient Variable Speed High Power Factor Three Phase Induction Motor Drive using Combined PWM and Extinction Angle Control Mrs. S.H. Deshmukh Student Department of Electrical Engineering SRCoEM

Ms. Medha R. Giri Student Department of Electrical Engineering SRCoEM

Afsana Shaik Student Department of Electrical Engineering SRCoEM

Dr. D.R. Tutakne Professor Department of Electrical Engineering SRCoEM

Abstract Paper presents a new energy efficient technique of three phase AC to AC voltage control using medium frequency pulse width modulation and extinction angle control. This technique is deployed to obtain independent control on speed and power factor of the three phase induction motor, using four semiconductor controllable switches. The technique has been realized using AC freewheeling switch. Power factor (PF) of induction motor reduces as it depends on the load parameters, thus induction motor draws more current, increase stator copper losses. Increased stator copper losses of induction motor causes depreciation of power factor and efficiency. Proposed drive maintains power factor of induction motor at unity for controllable speed of the motor. Thus reduces current consumption of the motor at low speeds. Stator copper losses also reduce and efficiency of the motor is improved. Advantage of proposed drive is its higher efficiency and unity power factor with simplicity of control. .If number of motors are driven using the proposed drive, plenty of power conservation is possible. Keywords: Extinction Angle Control (EAC), Pulse Width Modulation Control (PWM), Extinction Angle (β), Power Factor (PF), Induction Motor (IM) _______________________________________________________________________________________________________ I.

INTRODUCTION

Energy saving is energy generation. Now-a-days power conservation is an issue across the globe. Three phase induction motor is most widely used in industries than other machines due to their advantages such as simplicity in construction, reliability in operation, and cheapness. The speed control of such motors can be achieved by controlling the applied voltage on the motor by the use of power electronic devices [1]. AC voltage controllers as power converters are also used as induction motor soft starter .But this suffers from several disadvantages such as retardation of firing angle, poor input power factor, complex control techniques and large number of switches [2]. Three phase induction motors (IM) for fans and blowers applications in industries are mostly driven through variable voltage variable frequency (VVVF) drive that provides speed control of induction motor. With VVVF drive, power factor (PF) of induction motor reduces as it depends on the load parameters thus induction motor draws more current, increase stator copper losses. The proposed drive can operate induction motor with unity PF for any speed. Thus improves PF of an industry, using this drive. In addition, it offers free wheeling in AC load. Even for the operation where VVVF is not required with IM this drive can be installed to improve the overall PF of an industry. II. CONTROL TECHNIQUE Combined Extinction Angle and PWM Control This is a novel technique that is introducing a combination extinction angle (đ?›˝) control and PWM control for three phase induction motor drive. In this technique both the control technique will be acted simultaneously. In EAC control the conduction is started at zero crossing of the supply voltage, forced commutated at the (đ?‘¤đ?‘Ą = đ?œ‹ − đ?›˝) and also a freewheeling path is provided for the load current to discharge the stored energy of input voltage. In the conduction period from (đ?‘¤đ?‘Ą = 0) to (wđ?‘Ą = đ?œ‹ − đ?›˝), pulse width modulation control is applied i.e. in this conduction period output voltage waveform is in the form of number of pulses instead of single pulse in each half cycle. EAC technique is to provide leading power factor. PWM technique is used for better power factor (lagging). By using the combined technique advantages of extinction angle control along with merits of PWM control are employed for controlling induction motor drive, thus results in achieving unity pf for any speed and induction motor is expected to draw comparatively less current, thus stator copper losses of three phase induction motor are reduced. If All rights reserved by www.journalforresearch.org

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