Discussing details of lumped parameter thermal modeling in electrical machines

Lumped parameter thermal networks (LPTN) have been widely used for the thermal modeling of the electrical machine due to its low computing time. In spite of the simple structure of the network, much effort has to be invested to define the thermal circuit in a physically proper way. This paper discusses details of lumped parameter thermal modeling and explains where attention should be paid for an accurate model. Components with high discretization level are introduced, providing both average and hot-spot temperatures. The impacts of inhomogeneous losses and the correction of temperature dependent losses are analyzed. The paper uses the example of a switched reluctance machine. However, the obtained result can be applied to all machine types.