Design and implementation of PLC-based monitoring control system for three-phase induction motors fed by PWM inverter

Abstract

This paper presents a design and implementation of a monitoring and control system for the three-phase induction motor based on programmable logic controller (PLC) technology. Also, the implementation of the hardware and software for speed control and protection with the results obtained from tests on induction motor performance is provided. The PLC correlates the operational parameters to the speed requested by the user and monitors the system during normal operation and under trip conditions. Tests of the induction motor system driven by inverter and controlled by PLC prove a higher accuracy in speed regulation as compared to a conventional V/f control system. The efficiency of PLC control is increased at high speeds up to 95% of the synchronous speed. Thus, PLC proves themselves as a very versatile and effective tool in industrial control of electric drives.