Position Sensorless Control of an Interior Permanent Magnet Synchronous Machine (IPMSM) in Deep Flux-weakening Region

This paper investigates performances of a fractional-slot, concentrated wound interior permanent magnet machine in deep flux-weakening region under position sensorless control. Direct torque and flux control (DTFC) scheme that incorporates optimum operation was implemented. Position and speed were estimated using sliding mode observer (SMO) based techniques. Control scheme was experimentally verified on a 14-pole/18-slot fractional-slot concentrated-winding (FSCW) IPMSM. Experimental results show that performance of SMO-based position estimation is satisfactory in deep flux weakening region under voltage limited operation. However, the reference voltage vector requires compensation to operate with optimum transient performance.