Speed sensorless detection of rotor flux position for induction machines at low speed and standstill

This paper presents an advanced pulse pattern for saliencies based self sensing control of induction motors for electric vehicle drives. This allows a direct, accurate and parameter independent detection of the rotor flux position at standstill and low speed. The innovation of the proposed method is the reduction of the stator current to zero before each sequence of test pulses. This leads to a commutation of the magnetising current into the rotor leakage inductance and consequently to a saturation of this inductance in the same direction. Finally measurement results with the proposed injection sequence are shown and compared with state of the art methods.