Cooling structure design for an outer-rotor permanent magnet motor based on phase change material

Abstract

• A cooling structure of an outer-rotor PM motor based on PCM is proposed. • The structure can prolong the operating time by 149 s under 2 times overload. • The thermal conductivity of PCM is enhanced by porous copper foam. • The composite PCM prolongs the operating time by 16.8% compared with pure PCM. For a small-sized outer-rotor permanent magnet (PM) motor during overload operation, the internal heat increases sharply and the effective heat dissipation area is seriously insufficient. Aiming at the heat dissipation for the motor, given the limitation of size, a passive cooling structure based on phase change material (PCM) is proposed in this paper. The copper shell filled with PCM is mounted between the flange and end winding using the thermally conductive silicone. The three-dimensional model of the PM motor and the cooling structure is established and the heat dissipation is simulated by finite element method. The experiment is conducted and the results show that the cooling structure can prolong the operating time of the motor by 149 s under 2 times overload. Additionally, the PCM-copper foam composite consisted of PCM and porous copper foam is adopted to enhance the thermal conductivity. The experimental results show that the operating time of the motor is prolonged by 16.8% compared with pure PCM, and the overload capability is enhanced.