Thermal model of totally enclosed water-cooled permanent magnet synchronous machines for electric vehicle applications

Totally enclosed water-cooled permanent magnet machines (TEWCPMMs) have been widely applied in electric vehicles (EVs) due to its advantages of high torque density, high power factor and strong overloading capacity. However, the TEWCPMM is often experienced with extremely high ambient temperature in very limited space, which may lead to serious machine faults. In order to investigate thermal performance deeply, after investigation on the air convection within the end-space, this paper presents a thermal model, which takes the influence of the air temperature within the end-space on the temperature distribution by convection into consideration. Combining electromagnetic finite-element analysis (FEA) with thermal resistance network (TRN) of the TEWCPMM, the thermal model is established, which is based on the law of heat flux balance in two continuous iterative calculations. Finally, experiments are performed on a 36-kW prototype to validate the proposed thermal model.