基于多物理场的超高速永磁电机冷却系统设计及分析

Design and analysis of ultra-high speed permanent magnet motor cooling system based on multi-physical field

为了解决超高速永磁电机转子散热困难的问题,提出一种有效提高转子散热能力的散热结构。首先,采用计算流体动力学(CFD)仿真方法计算一台15 kW、15000 r/min水冷高速永磁电机的温升,将计算值与试验测得的数值进行对比,证明了CFD仿真方法的有效性。其次,通过孤立翼型法针对一台10 kW、100000 r/min表贴式超高速永磁电机设计了同轴轴流风扇,采用流体场与温度场耦合的方法仿真分析了风扇叶片数量和叶片安装角对电机温升的影响,从而得到风扇叶片的最优参数,抑制转子温升的同时降低风扇的风摩损耗。最后,通过仿真分析对比自扇冷却与强迫风冷的冷却效果,结果显示风量相当的情况下自扇冷却的永磁体温升相对于强迫风冷降低了13.8 K左右。经过应力场分析,风扇符合安全运行要求。

In order to solve the problem of heat dissipation of the rotor of ultra-high speed permanent magnet motor,a heat dissipation structure was proposed to improve the heat dissipation capacity of the rotor effectively.Firstly,the computational fluid dynamics(CFD)simulation method was used to calculate the temperature rise of a 15 kW,15000 r/min water-cooled high speed permanent magnet motor,and the calculated values were compared with the measured values,which proved effectiveness of the CFD simulation method.Secondly,a coaxial axial fan was designed for a 10 kW,100000 r/min ultra-high speed permanent magnet motor by using the isolated airfoil method.The influence of the number of fan blades and blade installation angle on the temperature rise of the motor was simulated by using the method of fluid field and temperature field coupling,so as the optimal parameters of fan blades was obtained to suppressing the temperature rise of the rotor and the wind friction loss of the fan was reduced.Finally,the cooling effects of self-fan cooling and forced air cooling were compared through simulation analysis.The results show that the temperature rise of permanent magnet cooling by self-fan cooling is about 13.8 K lower than that by forced air cooling under the condition of the same air volume.Through the analysis of stress field,the fan met the requirements of safe operation.