Permanent Magnet Assisted Synchronous Reluctance Machine with fractional-slot winding configurations

Abstract

This paper evaluates suitability of factional-slot winding configurations for Permanent Magnet Assisted Synchronous Reluctance Machine (PMA-SynRM) for applications in Electric Vehicle (EV) traction. Three typical factional-slot winding configurations, viz., concentrated nonoverlapping (12-slot 10-pole), conventional non-overlapping (12-slot 8-pole), and the overlapping (18-slot 8-pole) winding are employed for design of PMA-SynRM in order to improve power factor and torque density, and to reduce torque ripple and end-winding length over the conventional PMA-SynRM with distributed windings. All three machines are optimized against New European Drive Cycle (NEDC) efficiency via finite element analysis and thereafter compared quantitatively to evaluate their overall performance for EV traction applications. It is shown that PMA-SynRM with concentrated fractional-slot non-overlapping winding is more suited for in-wheel motor where the maximum speed is low, whilst the machines with the conventional fractional-slot non-overlapping winding and the fractional-slot overlapping winding exhibit high reluctance torque, high efficiency over a wide region and desirable flux weakening capability, thereby being attractive for high speed machines with reduction gear in EV traction applications.