MATLAB/simulink modelings and experimental design of variable frequency drive for speed control of three-phase induction motor

Abstract

This paper presents the PWM (Pulse Width Modulation) based speed control of three-phase asynchronous (Induction) motor. Induction motor is the leading machine used in many industrial controls, automation processes and in the field of HVAC applications. However, induction motor has fixed rated speed when directly connected to ac supply. It is necessary to design a drive system to obtain variable speed at its output to fulfill the application requirement. For this reason, we have designed a “VFD (Variable Frequency Drive)”, which gives desired speed-according to load changes unlike the DC motors, which do not require any speed controlling drive. Currently with the technological elevation in drive systems, the speed control of induction motor is more economical, convenient, reliable, and accurate. It provides continuous process control over a wide range of speed. VFD not only controls the speed of induction motor but also make its starting smooth by reducing starting inrush current and improves power factor. In result, power consumption is also reduced. In this paper, we have designed and analyzed the MATLAB/Simulink model of open loop drive system and then implemented an experimental hardware design.