Thermal Analysis of Outer Rotor PMSM Based on Flat Heat Pipe Cooling Method

Heat pipe is a kind of heat transfer element with very high thermal conductivity, which has a good application prospect in high power density driving motors. However, the complicated heat transfer process involves a variety of mechanisms, which undoubtedly increases the difficulty of temperature field modelling. Therefore, the equivalent thermal conductivity model of flat heat pipe (FHP) considering the influence of some factors was established. First, the mathematical model can fully consider the influence of the thickness of shell, the thickness of vapour chamber, the length of endothermic section and exothermic section on the equivalent thermal conductivity of FHP. Second, a test platform is built to test the equivalent thermal conductivity of FHP and the accuracy of established analytical model is verified. Finally, a 30-pole 36-slot high power density outer rotor permanent magnet synchronous motor (PMSM) is designed. Based on the FHP cooling method, FHPs placed in stator yoke are analysed, and the influence of different cooling structures on motor temperature rise is compared. At the same time, the effect of forced air cooling on the temperature rise of the motor is discussed, which provides a valuable reference for the application of FHP in the motor cooling.