Thermal modelling for permanent magnet synchronous motors based on electrical and thermal characteristics

The temperature rise inside permanent magnet synchronous motors (PMSMs) caused by losses can lead to potential irreversible demagnetisation of magnets, insulation failure between windings, etc. This paper presents an analytical model to predict the PMSM temperature based on the electrical and thermal characteristics. The temperature relationship between motor windings and permanent magnets is addressed through the electrical modelling. Meanwhile, one lumped-parameter based thermal model is developed and combined with the electrical model, which will avoid processing the complicated aspects of thermal analysis and picture the thermal distribution inside PMSM conveniently. Furthermore, the thermal circuit encompasses the eddy current loss in the magnets, which provides high accuracy. The predicted temperature through the proposed model is validated by finite element analysis (FEA) simulation when the motor is operated under a three-phase sinusoidal power supply.