High Efficiency Hybrid Synchronous Motor Design with Loss Analysis for a Two-Speed e-Powertrain System in Electric Vehicle

With high efficiency and high flux-weakening capability, hybrid synchronous motor (HSM) is a competitive alternative as a cost-effective solution for traction applications. This paper presents a cascaded and systematic method to define specifications of target motor and design a high efficiency 172 kW, 18000 rpm HSM for a two-speed e-Powertrain system. Vehicle-level specifications and gear ratio combinations are taken into consideration to determine motor requirements. Four concept rotor typologies are investigated to obtain efficiency maps for comparisons in simulation models. Detailed loss analyses are done at both base speed and maximum speed for a selected HSM. 0.2 mm stator lamination and 4 segmented magnets in each magnet slot have been applied to further improve motor maximum efficiency. Performance tests are completed in the dyne bay to show that 97.5% maximum efficiency is achieved.