Holistic Design Optimization of 350 kW High-Speed Permanent Magnet-Assisted Synchronous Reluctance Machine for Heavy-Duty Electric Vehicle

The widely adopted “high-speed machine + high-ratio gear” solutions for passenger electric vehicle (EV) drivetrains are yet to be explored for demanding heavy-duty applications. This article will investigate 350-kW level high-speed traction motor development based on permanent magnet (PM)-assisted synchronous reluctance machine (PMaSyRM) topology. With the overall target of boosting active power density under threshold of materials’ performance boundaries, multiphysics solvers are configured by both analytical and simulation tools to tackle design challenges in electromagnetic, mechanical, and thermal domains. To deal with multiple design parameters and performance indicators, a three-stage hierarchical development platform is proposed and implemented to feature not only comprehensiveness but also balanced computation resource consumption and accuracy. Apart from globally parametrized machine geometry, the usually predefined slot number and pole number are looked into in the first and second stages, respectively, and are downselected due to their substantial influence on material usage and loss distributions. In the final stage, a novel mechanical stress design concept is proposed, which significantly accelerates the “electromagnetic + mechanical” coupled rotor design process. Moreover, three typical cooling strategies are quantitatively evaluated for further downselection of the most suitable thermal management. The finalized design is validated by a 1:1 PMaSyRM prototype with 580-Nm peak torque and 15 000-r/min peak speed, which features an active power density of 6.3 kW/kg.