Performances of a Fractional-Slot Concentrated-Winding Permanent Magnet Synchronous Machine Under Position Sensorless Control in Deep Flux-Weakening Region

In recent time, the use of fractional-slot concentrated-winding (FSCW) stator has made it possible to drive the interior permanent magnet synchronous motors in very deep flux-weakening speed range. Many of such motors can operate along the maximum torque per voltage (MTPV) trajectory during the deep flux-weakening operation. Performances of the FSCW interior permanent magnet synchronous machine (IPMSM) while operating along the MTPV trajectory in the deep flux-weakening region under sensorless direct torque and flux control are yet to be investigated thoroughly. A 14-pole/18-slot FSCW IPMSM, which has a flux-weakening speed range of 9:1, was investigated in this paper. The position and speed were estimated using a sliding mode observer. Experimental results showed that satisfactory dynamic operation was possible during deep flux weakening only when a voltage compensation technique was integrated. This paper attempts to investigate the underlying reasons behind the requirement of the additional voltage compensation during deep flux weakening in the FSCW IPMSM.