Numerical analysis of a PM synchronous motor used in electrical vehicles

The paper presents a FEM numerical model of a permanent magnet synchronous motor used in electrical vehicles. The motor is mounted directly on the vehicle wheel and has 2p=28 poles, Z=21 slots. The stator winding is made of field coils wound around each tooth. This configuration allows obtaining high torques at low speeds, reduced motor size, high efficiency, short end coils, high slot fill factor and low cogging torque. The winding slot distribution produces high harmonic content in the air-gap MMF. High order harmonics are not synchronous with the rotor speed. Also, several harmonics are rotating against the main field generating negative effects, such as eddy currents producing losses in the surface mounted PMs and in the rotor iron core. The numerical model is a field-circuit model that takes into account the rotor's movement and, in addition to classic reviews, also the induced currents in the rotor.