Waterway design of an external rotor permanent magnet synchronous generator

An external rotor permanent magnet synchronous generator (ERPMSG) model for Range-Extended Electric Vehicles is developed. The temperature field simulation model of the ERPMSG is established. Experimental test of the winding temperature shows that the simulation model is believable and then it is used to optimize the structural parameters of the cooling water channel. It is found that the pressure loss increases with the number of layers of the cooling water channel increasing and the width of the water channel decreasing. In order to obtain a large turbulent effect and a minimum pressure loss simultaneously, the number of layers of the cooling water channel is set to be 3 and the width of the waterway 8 mm. The corner of the water channel is designed round with an optimum radius of 20 mm. After optimization, the cooling performance of the ERPMSG is obviously improved. Compared with the ERPMSG before optimization, the temperature of the ERPMSG with optimum structure parameters of the cooling water channel is lower. The maximum temperatures of the winding, the stator core and the rotor of the ERPMSG with optimum structure parameters of the cooling water channel decrease 8.19 °C, 5 °C and 7.42 °C respectively. Temperature distribution is more uniform in the permanent magnet of the ERPMSM with waterway structure optimization.