Analysis and Design of Air-heat pipe Composite Cooling of High Power Density Motor

•The thermal conductivity of the heat pipe is affected by multiple factors.•An air-heat pipe composite cooling technology applied to motors is presented.•It will reduce the stable temperature of windings by 19.6K.•It will prolong the overload operation time by 12.7%. High power density and short-term high overload performance motor is an important part of the aircraft's electric propulsion system. The efficient heat dissipation system can effectively control the temperature rise of the motor, which provides the possibility to improve the power density of the electric propulsion system. An air-heat pipe composite cooling system was designed by using heat pipe technology and the application environment of aviation motors. Firstly, a new composite cooling system was designed based on the structure and loss distribution characteristics of a 34kW external rotor aero-motor; then four different U-shaped heat pipes were designed and fabricated. In order to select the optimal heat pipes to ensure the efficient performance of the composite cooling system, a test platform was built to carry out experimental research on the thermal conductivity of the heat pipes and the variation laws of thermal conductivity. Then the performance of the composite cooling system is evaluated and verified based on a combination of simulation and experiment. The results show that the cooling effect is better by arranging the heat pipes at the bottom of the stator slot of the motor, which can reduce the stable temperature rise of the motor winding by 19 K and prolong the overload operation time of the motor by 12.7 %. The high efficiency of the composite cooling system can effectively improve the power density of the motor.