A Modified Method of Control for Induction Motors Based on Instantaneous Reactive Power Theroy

This paper proposes a new method of sensorless vector control for induction motors,in which the motor speed is estimated by both instantaneous reactive power and variation of magnetizing current.The proposed system is constructed in a synchronously rotating reference frame and is very simple.A linear model is deduced to analyze system stability.According to the trajectories of poles and zeros,the system gain is selected to be suitable for operating in a wide speed range and in motoring or regenerating mode.The feasibility of the proposed system is verifed by digital simulation.