Variable characteristics technique on permanent magnet motor for electric vehicles traction system

A traction motor system of electric vehicles (EVs) requires wide torque-speed operation range, high efficiency, and low torque ripple according to its driving point. To achieve the requirements without increasing motor size, a novel variable characteristics motor system is proposed in this paper. A winding structure is studied to reduce unprofitable conductor which makes conduction loss. The developed system is applied 48-slot 8-pole permanent magnet synchronous motor (PMSM). The motor has structural full-pitch distributed winding with 12 open-end windings connected to insulated 12 full-bridge inverter. The developed motor simulates 4 types of winding mode, and each characteristic are calculated based on static two dimensional finite element analysis (2D-FEA). The calculated results show increase torque-speed operation range, higher efficiency, and lower torque ripple by selecting appropriate winding mode.