One of the most important components of an electric vehicle is the drive motor. Induction motors are often used for this purpose. Power losses occur during the operation of these motors, particularly at high speeds. Among other things, this power loss corresponds to the sum of winding losses, iron core losses and mechanical losses. The power losses generate heat, causing the temperature in the rotor and stator to rise. The increase in temperature of the components inside the motor can lead to premature wear and fatigue failure. To prevent overheating, the motors are air or water cooled. Water cooling can be achieved by jacket cooling, for example. In this case, the heat generated is dissipated directly by forced convection. However, the cooling jacket makes it difficult to determine the temperature inside the motor. Determining these temperatures is necessary to prevent the motor from fatiguing prematurely. The temperatures that occur inside the motor during operation are of particular interest for the thermal design.
This paper presents the modelling and thermal analysis of a water-cooled electric motor for electric vehicle applications based on test bench tests. A thermally transient model design based on test bench measurements is explained. The motor is designed using the geometry of the test bench machine in ANSYS Motor CAD. The model is validated with test bench measurements. This includes surface temperatures of the motor housing, coolant and ambient temperature, as well as the speed of the electric machine. The special feature here is the determination of the surface temperature using thermography. This allows significantly more temperatures to be recorded than with thermocouples. The purpose of the work is to simulatively determine the temperatures inside the machine based on measured surface temperatures using thermography.