Sensorless vector control of induction machine using high frequency current injection

This paper describes a new approach to estimate the rotor angle of an induction machine from measured terminal voltages and currents using high frequency current injection for sensorless vector control. The proposed scheme is independent of load variation since the rotor angle is derived by using only the injected d-axis current, also it is robust to parameter variation because only the stator resistance is used. Besides, since the strategy depends on only the flux phase, not on the flux magnitude, the rotor angle deviation due to the error of the flux estimation is much less than other schemes. Therefore the performance of vector control at low speed region is considerably improved. The validity of the proposed scheme is confirmed by experimental results