Optimisation of an 80kW Segmental Rotor Switched Reluctance Machine for automotive traction

There is significant interest in the development of Switched Reluctance Machines for use in automotive traction applications. This has been driven by their low cost compared to Rare Earth Permanent Magnet based motors, coupled with their potential for competitive torque densities. This paper describes the development of a variant of the Switched Reluctance Machine, utilising a Segmental Rotor construction, which has previously been demonstrated to provide up to a 65% improvement in torque densities compared to Switched Reluctance Machines with a conventional toothed rotor construction. The paper describes a strategy which has been developed to optimise the Segmental Rotor SRM in order to achieve performance equivalent to that of the 80kW Interior Permanent Magnet machine utilised in Nissan's LEAF electric vehicle. Optimisation applies a combination of static and dynamic analyses in order to achieve a full and computationally efficient assessment of motor performance across different regions of the torque speed envelope.