A review of structural design for in-wheel motors in new energy vehicles

Abstract

The in-wheel motor (IWM) drive system represents one of the most promising architectures for new energy vehicles (NEVs), offering distinct advantages in drivetrain efficiency, vehicle packaging flexibility, and independent wheel torque control. This review systematically examines the structural design aspects of in-wheel motors, encompassing electromagnetic topologies, mechanical integration, thermal management, and fault-tolerant configurations. Particular emphasis is placed on permanent magnet synchronous motor (PMSM) variants, including surface-mounted, interior, axial-flux, and transverse-flux arrangements, as well as the critical challenges of unsprung mass augmentation, thermal rejection in hostile wheel environments, and sealing reliability. The paper synthesizes recent advances in multi-objective optimization, novel manufacturing processes, and integrated suspension-motor co-design strategies. By analyzing comparative performance metrics and identifying persistent technical barriers, this review aims to provide a comprehensive reference for researchers and engineers engaged in next-generation electric propulsion system development.