A design of robust speed controller for speed sensorless stator-flux-oriented induction motor drive

In a conventional speed sensorless stator-flux-oriented (SFO) induction motor drive system, the estimated speed is delayed in transients by the use of a low pass filter (LPF). To prevent extreme overshoot of speed caused by this delay, the gains of speed regulator should be small. Consequently speed response is greatly affected by disturbance torque. In this paper, by taking advantage of disturbance torque observer and feedforward control, robust speed controller is designed for speed sensorless SFO system. The proposed method is verified by simulation and experimental results.