Stability improvement of speed sensorless induction motor vector control system using q-axis flux with stator resistance identification

We have proposed a speed sensorless vector control system for induction motors using q-axis flux with parameter identification. In this paper, we go further to discuss the system stability in both motoring and regenerative operation by computing the pole-zero trajectories of the linear model, with the emphasis on the error influence of stator resistance and its identification gain. The stability improvement is significant by changing the sign of the identification gain, according to the motor operation state. The effectiveness is verified by digital simulation and experiment.