Control of Induction Motor Drives –Technological Advancements

Abstract

The induction motor (IM) with variable frequency AC inverter is widely used in industrial applications which require good dynamic and steady state performance over a wide range of speed. Scalar control has always been inaccurate and gives poor dynamic performance due of the coupling between variables. Vector control by rotor flux orientation drives the machine analogous to a DC machine and offers good dynamic performance for a wide range of application. However, the dynamic performance is dependent over the precise measurement of rotor flux, torque and speed. Direct torque control (DTC) on the other hand reduces the complexity of speed measurement, but requires flux and torque estimation. In this paper, industrial benefits and problems of DTC method has been discussed and reviewed with the latest improved available solutions of such problems. The problem of real time flux estimation over wide range can be overcome by using sensorless control of IM. In this paper estimation techniques of flux magnitude and its position are also reviewed and presented.