Design and Development of Variable Frequency Drive for Three Phase Induction Motor using Microcontroller

Abstract

Induction motor for many years has been regarded as the workhorse in industrial applications. In the last few decades, the induction motor has evolved from being a constant speed motor to a variable speed, constant torque or variable torque ma- chine. With the invention of variable voltage variable frequency drives (VVVF), the use of an induction motor has increased. Variable voltage variable frequency control provides a simple and cost efficient method for open-loop speed control of three phase induction motor. This technique is popularly known as V/f control. In this report principle and operation of V/f drive is summarized, various speed con- trol techniques are discussed. Simulation of V/f drive using SPWM technique is presented. The model is generated in MATLAB Simulink and results are obtained for different frequencies. This report also provide algorithm of modulation technique for Sine-Wave Weighted PWM pattern generation. The control strategy to obtain PWM pulses has been implemented by microcontroller. This report include hardware implementation of IGBT driver inverter module, Fre- quency control module, PWM generation module and Rectifier bridge module. A low-cost, simple design Variable Frequency Drive is implemented for Three Phase In- duction Motor. Experimental results of Voltage, Current and Speed are also carried out on different frequencies.