Scalable Thermal Model of an Electric Machine for the Thermal Assessment in Different Electric Vehicle Use Cases

In this paper, a scalable thermal model of a permanent magnet electric machine is presented. The model is designed to simulate the temperature development of active machine parts during different driving cycles depending on the machine diameter, the length, and the turns per coil. The impact of the various parameters is demonstrated by means of a sensitivity analysis. The sensitivity analysis is performed for two different driving cycles and two different vehicle types in order to outline the dependence of the general vehicle layout and the use case on the thermal machine behavior. Only machines that are able to perform the respective duty cycle are considered. It shows that despite the increase in thermal heat capacity, big machines do not always experience the lowest temperature during transient operation. The method demonstrated in this paper allows a thermal assessment in an early development stage, when machine scaling is used for a first estimation of the required volume of the PMSM.