Multiphysics Design and Optimization of High-Speed Traction Motors

The recent shift toward electrified powertrains has increased the demand for electric motors that are low-cost, compact, and offer high power density. This paper proposes the use of high-speed rotors, which enable a reduction in stack length and, consequently, lower material costs. While shortening the stack reduces peak torque, the power-speed characteristics of the traction motor remain largely unchanged. However, the elevated rotational speeds introduce significant mechanical stresses within the rotor core. To address this, the paper presents a holistic co-optimization framework for traction motor design that simultaneously satisfies electromagnetic, mechanical, and thermal requirements at rotor speeds exceeding 20,000 rpm. Multiphysics simulation results demonstrate that increasing the rotor speed to 25,000 rpm can reduce material costs by 37% while preserving vehicle-level performance when compared to the baseline design.