Estimation of Continuous Power of a Permanent Magnet Synchronous Machine Equipped with Direct-Liquid-Cooling Winding for Propulsion Applications by EFA

Increasing the specific torque and power of a propulsion permanent magnet synchronous machine (PMSM) is important for the improvement of the performance of electrical vehicles. Among all technologies, increasing the current density and at the same time increasing the cooling capacity accordingly might be the most promising one. In this paper, the specific power of an outer-rotor PMSM is investigated by using different winding impregnation techniques. Both stator water jacket and winding direct liquid cooling are utilized. The continuous power of the designed PMSM is estimated by 3D thermal finite element analysis (FEA). For the sake of simplicity of the 3D FEA, equivalent thermal conductivities in the whole conducting region with different materials are first estimated by more detailed 2D FEA. After that, the estimated equivalent thermal conductivities are applied in 3D thermal FEA. The continuous power of the PMSM is further estimated based on temperature constraints. It is found out that the winding impregnation technique has a significant impact on the equivalent liquid-cooled winding thermal conductivity and, as a result, on the continuous power of the PMSM.