Design and Optimization of a high torque in-wheel surface-mounted PM synchronous motor using concentrated winding

This paper presents a specific design process of a high-torque direct-drive in-wheel permanent magnet synchronous machine (PMSM) using concentrated winding and grain oriented (GO) silicon steel teeth for a hybrid All-Terrain Vehicle (ATV) application. Mechanical specifications and constraints of an off-road application are first demystified. An analytical design model, considering magnet flux and an induction reaction correction factors, is developed and used to determine geometric dimensions of a radial flux machine topology with surface-mounted permanent magnets (PM) and external rotor. The model also takes into account losses in winding, magnets, stator and rotor yokes and teeth. Electrical parameters of the equivalent machine circuit are determined to adapt the machine to the imposed converter voltage. All critical machine models parameters are validated with finite element (FE) simulations. The analytical design model is used to perform an iterative optimization procedure. This model is corrected during the optimization process by using correction factors derived from 2D FE analysis. The optimization process and some critical design validations are presented.