PWM FED Speed Control of Induction Motor

             The induction motor has finding enormous applications in industries in these days, due to its advantages the utilization of induction motors are increasing day by day, so in order to attain proper functionalities we need to regulate the speed of this induction motor, the speed of the induction motor is controlled by resistance control on rotor or stator side, stator voltage control, or by pole changing method but these conventional method  are not so effective in controlling the speed of the induction drive so in order to full fill the requirements like low noise, high accuracy, less ware and tear with less operational speed we implemented an new concept in this paper i.e.

            “PWM fed speed control of induction motor controlled by  the computer”. Here in this project we generate numerous pulses in every half cycle such that the width of the pulse is less at the end and beginning of the half cycle and maximum at the center, and this width of the pulse varied by the amplitude of the reference sine wave, such that the amplitude of the carrier wave is less than the reference sine wave and these two signals are mixed in the comparator, the output signal frequency is controlled by the modulation index.

             The proposed system consists of power supply circuit, Microcontroller, opt-isolator used as a driver circuit, MAX232 integrated circuit, TRIAC and an LCD to display for the output. The power supply consists of a step down transformer to obtain 12v ac from 230v ac and an full bridge rectifier to gain 5v dc for the circuit operation, we use an PIC (16F877A) micro controller to control the operations of this device, asynchronous receiver/transmitter is used to transmit the data between parallel and serial lines.

              The entire set up and working phenomenon is explained neatly along with the experimental results