A comparison between maximum torque/ampere and maximum efficiency control strategies in IPM synchronous machines

This paper presents a comparison between maximum torque/ampere and maximum efficiency control strategies for interior permanent magnet synchronous machines (IPMSMs) in an electrical vehicle propulsion application. A mixed theoretical and experimental approach is adopted to demonstrate how an improvement in performance may be achieved when maximum efficiency control is utilised. The study is completed on three machines, a 36 slot 10 pole fractional slot per pole distributed winding, a 30 slot 10 pole integer slots per pole distributed winding design and a 12 slot 10 pole concentrated winding design. The findings are experimentally validated on the 36 slot 10 pole IPM motor. It is shown that the largest improved in efficiency is achieved with a concentrated winding design however for all three designs a significant efficiency gain is achieved in the most common operating regions of the standard international and US urban drive cycles, WLTP and UDDS.