Stability improvement of vector control system of induction motor without speed sensor using synchronous current regulator

This paper presents a stability analysis of a speed sensorless vector control (SSVC) system of an induction motor. The stability analysis takes into account the effects of three current control loops. The poles and zeros of the transfer functions for the rotor speed are calculated to investigate the influences of controller parameters and motor parameters. The theoretically derived step responses are compared with the experimental results. Also, the Bode diagrams of the transfer functions for the torque producing current are calculated. This paper discusses the suitability of different current regulator (CR) methods for the SSVC system of an induction motor.