Dc control

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2009 International Conference on Education Technology and Computer

Variable Speed Drive of Single Phase Induction Motor Using Frequency Control Method
Mr. Aung Zaw Latt
Department of Electrical Power Engineering Technological University (Myitkyina) Myitkyina, Myanmar azlatt@gmail.com
Abstract— Single-phase induction motors are widely used in home appliances and industrial control. Themultispeed operation and multipurpose operation are provided by controlling the speed of these motors. This research paper is variable speed drive of induction motor using frequency control method. It is to develop the solid state control system to be reliable and economically feasible to use with fractional horse power motors. The proposed variable speed drive includes power conversion section (AC toDC and DC to AC), used the switching element of IRF 840 N-channel MOSFET. The four IRF 840 MOSFETS are used as H-bridge inverter to provide the alternating current to the motor. In this drive, C124 transistors and MJE 13002 transistors are used as driver circuit to drive the H-bridge inverter. There are two power supplies in this drive. The 12 V power supply is used for frequency control circuitand driver circuit. The 300 V power supply is used for H-bridge inverter. In this drive, pulse width modulation SG3525A IC is used to control the frequency. The frequency range of the constructed variable drive circuit is 16 Hz to 56 Hz at constant voltage for changing the speed of induction motor. In this research paper, drive schemes of single-phase induction motor, principle operations ofcomponents used in constructed variable speed drive, and design calculation to construct this drive are included. Moreover, the experimental tests of this drive when driving a fractional horse power single-phase induction motor are described. Keywords- driver circuit, frequency control circuit, induction motors, switching element, variable speed drive

Dr. Ni Ni Win
Department of Electrical PowerEngineering Mandalay Technological university Mandalay, Myanmar Phone: 095-02-88712, Fax: 095-02-88702 reliable, etc.There are probably more single-phase induction motors in use today than the total of all the other types put together. It is logical that the least expensive, lowest maintenance type motor should be used most often. The single-phase induction motor best fits this description. Theinduction motor can run only at its rated speed when it is connected to the main supply. However, they are constant motor. To control the speed of these motor, a motor drive and control system with different methods can be used. An induction motor’s speed enable affected by the supply frequency, change the number of motor stators, adjust the power input. Over the past several years there have advancesin solidstate control technology and how it can be used to control motors. Solid state controls are usually very reliable, can give exact speeds and are becoming more economically feasible to use with fractional horse power motors. Most of the different styles of solid state controls incorporate the varying of the frequency to control the motor speed. They can vary the frequency to be higher thanthe normal line frequency, meaning the speed can be increased beyond what the motor is rated for. Moreover they are simple to implement and cost effective. II. LOAD CHARACTERISTICS OF INDUCTION MOTOR

I.

INTRODUCTION

Most of the drives used in the industrial motor control are electrical. Depending on the application, some of them are fixed speed and some are variable speed. The variablespeed drives had various limitations such as poor efficiencies, larger space, lower speed, etc,. However, the advent of power electronics transformed the scene completely and today variable speed drive which are not only constructed smaller in size but also obtained very efficient and higher

In real applications, various kinds of loads exist with different torque-speed curves. The motor load...
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