Optimized INFORM-measurement sequence for sensorless PM synchronous motor drives with respect to minimum current distortion

In the paper a standard measurement sequence for INFORM-based sensorless position estimation of permanent magnet synchronous motors is analyzed and its properties with respect to the current deviation before and after the measurement are pointed out. Based on that a modified operating point adjusted measurement sequence with minimum current deviation and minimum time demand is introduced. Measurement results verify the improvement of the modified measurement sequence: The current distortion is reduced significantly resulting in reduced additional losses caused by the INFORM-measurement. Additionally, in the paper several measurement results concerning the performance of the sensorless position estimation under various load conditions are presented.