Heat transfer coefficients in a coupled 3-D model of a liquid-cooled IPM traction motor compared with measurements

Modelling of electrical machines is constantly refined and it is now possible to couple numerical thermal models and electromagnetic models, thereby allowing to examine the thermal effects on motor materials. In this paper it is shown how a 3-D model of an interior permanent magnet (IPM) motor, including power loss in the end windings and the effect of air and liquid cooling can be made where simulation results are compared with measurements. Further, it is shown how the coolant inlet temperature and volumetric flow rate affects the heat transfer coefficient of the cooling duct for some load points within the torque-speed range of the motor