This paper deals with the thermal modeling and analysis of bearingless permanent magnet (PM) synchronous motors (BPMSMs). A thermal model of the BPMSM is proposed with considering eddy current loss of PMs, copper loss as well as core loss of the stator. To enhance the accuracy of the thermal analysis, core losses of stator core and eddy current losses of PMs are calculated by finite element method (FEM). Furthermore, the heat source, equivalent thermal conductivity of stator/rotor core, equivalent insulation of stator windings insulation, equivalent thermal conductivity of the air gap, and convection coefficients in each motor surface are considered. Finally, the temperature distributions of the BPMSM in three different operation conditions are analyzed in detail. According to the simulation results, it is found that the overheat on PMs and all windings will happen during the peak power condition, and simulation results can provide further basis for the design of BPMSMs, such as insulation level of the winding, the selection of the PMs and the cooling system. Moreover, it lays the theoretical foundation on further studies.
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