高速永磁电机转子空气摩擦损耗研究

Research on Rotor Air Friction Loss of High-speed Permanent Magnet Machines

高速电机旋转速度每分钟数万转甚至高达数十万转,其转子表面的空气摩擦损耗要比普通电机高得多,在总损耗中占有较大比例。转子表面的空气摩擦损耗与电机转速、气隙结构及转子表面粗糙度等多种因素有关,很难通过理论分析和解析方法准确计算。基于3D流体场模型,对高速永磁电机的转子空气摩擦损耗与电机转子转速、表面粗糙度及轴向风速的关系进行了分析,并针对一台额定转速60000r/min的磁悬浮转子高速永磁电机,进行了转子空气摩擦损耗的计算及测试方法研究。通过电机空载试验,根据转子空气摩擦损耗和定子铁耗与电机转速之间的关系,可将空气摩擦损耗从总损耗中分离出来。实验结果和计算值一致,表明基于流体场分析的高速电机转子空气摩擦损耗计算方法是有效的。

For a high-speed machine,the rotor speed can reach up to or even above 10 000 r/min,and the air friction loss of its rotor surface is much greater than that of a traditional one,which accounts for a large proportion in the total losses.Since the air friction loss is affected by many factors,such as rotor speed,structure of air-gap,roughness of rotor surface,etc,it is difficult to accurately calculate the air friction loss by theoretical analysis.In this paper,the relationship between rotor friction loss and rotor speed,the roughness of rotor surface,and the axial velocity of airflow were investigated based on 3D fluid field analysis.Taking an example of a high-speed permanent magnet（PM） machine whose rotor is magnetically suspended with rated speed of 60 000 r/min,the calculation and experimental determination methods for air friction loss were studied.Through the no load experiments for different speeds,the friction loss can be separated from the total losses of the machine based on the relationship between the air friction loss and rotor speed determined by the 3D finite element analysis of fluid field.The calculated friction losses accorded with the tested results,which proved the validity of the proposed calculation method for friction loss.