Design and performance of slipring-less winding excited synchronous motor for hybrid electric vehicle applications

This paper presents an investigation into design possibility of slipring-less winding excited synchronous motor (SWE-SM) for traction drives in HEVs. The advantages of this machine are easy cooling of all active parts in the stator and robust rotor structure that makes it better suitability for highspeed motor drive system application. The design target is the motor with maximum torque of 115Nm, a maximum power of 60kW, a maximum power density more than 2.7kW/kg, and a maximum speed of 25,000r/min with similar restrictions and specifications in interior permanent magnet synchronous motor (IPMSM) used for the 2009 Toyota Prius. Some design refinements based on 2D-FEA are conducted to achieve better torque-speed characteristics and power production. As the design results, the designed motor enables to keep the same power density in existing IPMSM installed on a commercial HEV.