Towards Comprehensive Encoderless Motor Drive Systems for Railway Traction Applications

Abstract

An optimal encoderless saliency-based motor drive system should exhibit the same control performance than its sensor-based counterpart while removing the need for position sensing at any stage. This includes the initial commissioning stage at which all motor saliency attributes are identified. However, the existence of a load-dependent phase difference between the saliency vectors and the actual position poses an evident challenge for the realization of encoderless commissioning. Without taking the saliency phase shift into consideration, encoderless control performance during load transients worsens. In this work, a saliency commissioning method is presented, capable of accurately identifying saliency amplitude and phase shifts without position sensor. Thus, the shaft encoder dependency during the commissioning stage is removed. The method is experimentally tested on two different multi-salient traction motors.