Design of IPMSM for EV Propulsion to Improve Torque and Efficiency Characteristics Considering Temperature Variation

The interior permanent magnet synchronous motor (IPMSM), widely used in electric vehicles, shows performance variations with temperature, which can impact control accuracy and driving range. Therefore, this article derives the rotor shape of IPMSM to reduce performance deviation under temperature variation. First, the overall operating characteristics of IPMSM in response to temperature variation, such as constant torque curve and maximum torque per ampere trajectories, are analyzed. Second, the effects of temperature on efficiency of IPMSM are investigated. As a result, for reducing rated torque and efficiency deviation caused by temperature changes, the proportion of reluctance torque needs to be increased. Furthermore, the improvement design considering temperature variation are conducted using machine learning based meta models and multi-objective optimization algorithm. Finally, to validate the theoretical analysis and numerical simulations, a prototype is fabricated and tested.