Three Phase Induction Motor Speed Control Using Frequency Convertor via Programmable Logic Controller (PLC)

Abstract

Induction motor speed is controlled either by changing the number of poles or by changing the supply frequency. The frequency convertor is an electronic device that used to change the speed of the induction motor by converting alternating current of one frequency to alternating current of another frequency. The frequency converter rectifies AC voltage from main supply into DC voltage, and then it changed to an AC voltage with variable amplitude and frequency. The motor thus receives a variable voltage and frequency, which enables variable speed control of three-phase AC motor. Using Programmable Logic Controller (PLC) with PROFIBUS cable and three sensors, the speed of the induction motor is controlled easily.