Thermal Analysis and Verification of PMSM Using LPTN Considering Mechanical Components and Losses

In order to estimate the thermal characteristics of electric machines, the research on the lumped parameter thermal network (LPTN) has been carried out in this paper. Specifically, to improve the accuracy of the thermal analysis of the LPTN, the effect of the cooling fins on the frame, thermal modeling of bearing and the mechanical losses which can be divided into windage loss and bearing loss have been investigated. To reflect in the LPTN, the mathematical equation which describes the heat transfer through the cooling fin is derived and verified by the experiment. Moreover, the mechanical losses were obtained through experiment and divided into windage loss and bearing loss as a function of the rotational speed. Finally, the thermal analysis results ascertained through the LPTN are verified by comparing the temperature saturation test at no-load conditions. To verify the thermal analysis results, the 6-pole/9-slot interior permanent magnet synchronous machine is proposed.