Electromagnetic Design of an Interior Permanent Magnet Motor for Vehicle Traction

This paper reveals the design process of a 15:1 constant power speed range 75 kW motor for an electric vehicle application. The paper starts with a summary of the conceptual design process, which analyzes the pros and cons of various motor topologies (induction, spoke-type IPM and multi-barrier IPM) and type of magnet (high energy NdFeB and low energy ferrites). Then, the tradeoffs affecting the results of the preliminary design are shown. Finally, a detailed description of the final design is disclosed, focusing on motor performance, efficiency, torque oscillation mitigation and risk of demagnetization of the permanent magnets.