Review on Thermal Behavior and Cooling Aspects of Axial Flux Permanent Magnet Motors–A Mechanical Approach

With the increasing demand for high-energy density motors for applications such as electric vehicles and aircraft propulsion, axial flux permanent magnet motors are promising. However, utmost care should be taken when designing an axial flux permanent magnet motor with a higher torque density because of thermal effects. To enhance the reliability and overall performance of a motor, efficient thermal management is important, because the torque density is restricted by maximum temperature. Therefore, this study comprehensively reviews different techniques used for the thermal modeling of motors. Computational fluid dynamics, the lumped parameter method, and finite element analysis were used to calculate the total heat transfer inside the motor. Various heat enhancement techniques for an axial flux permanent magnet motor have been presented, including core cooling (water jacket cooling, air cooling, and oil cooling) and winding cooling (direct slot cooling, end winding cooling, and fins). Finally, two case studies of an 8kW AFPM motor and a 65kW AFPM motor with a cooling arrangement are discussed.