Active Flux Position Observer for Sensorless Direct-Flux-Vector-Control at Low Speed

This paper extends the Active Flux position observer in the low speed region, for sensorless Direct Flux Vector Control of permanent-magnet-synchronous and synchronous-reluctance motor drives. Active Flux observers are popular for back-emf based sensorless control in the medium and high-speed range of the electrical drive. In this paper, the High-Frequency Active Flux approach is used in the low and zero speed region with square wave voltage excitation. The proposed HFAF method allows to control the motor with no need for band-pass filtering nor de modulating the high-frequency signals. Experimental validation is carried out on 1.1 kW Synchronous Reluctance machine proving the effectiveness of the proposed method in speed control.