A comprehensive approach for design and optimization of a high power density interior permanent magnet motor for EVs

This study presents a comprehensive design and optimization framework that addresses both electromagnetic and thermal aspects of an interior permanent magnet synchronous motor (IPMSM) intended for use in midsize commercial EVs. A 60-slot/10-pole IPMSM with a V-shaped rotor, capable of delivering 125 kW peak power at 4500 rpm from a 400 VDC bus, has been developed using a systematic approach. The design process begins with analytical estimations to determine initial motor geometry and performance parameters, followed by a finite element-based validation. To enhance performance, a multiobjective optimization is conducted using the nondominated sorting genetic algorithm II (NSGA-II). The optimization targets three key objectives: maximizing average electromagnetic torque, maximizing torque-to-magnet volume ratio, and minimizing torque ripple. Sensitivity analysis is employed to identify the most influential design variables, enabling a more efficient and focused optimization process by narrowing the design space accordingly. Postoptimization, thermal validation is performed using a detailed lumped-parameter thermal model. A liquid-cooling system featuring an axial water jacket is implemented to ensure effective heat removal from the stator. The thermal analysis confirms that the optimized motor maintains safe operating temperatures, thereby validating the design's robustness under high power density operation. The proposed methodology demonstrates a holistic design approach that integrates electromagnetic optimization with thermal feasibility, resulting in a high-performance IPMSM suitable for demanding EV traction applications.