空压机用高速永磁电机铁心和磁钢损耗的影响因素

Influential Factors of Core Loss and Magnet Loss of High-Speed Permanent Magnet Motor Used in Air Compressor

高速电机具有电流频率高、定子铁耗和转子涡流损耗大等特点。针对额定功率10 kW、额定转速100000 r/min空压机用高速永磁电机,对比分析了平行充磁和径向充磁、脉冲振幅调制(PAM)方波驱动和基于SiC的正弦波驱动时对损耗的影响。分析结果表明,平行充磁气隙磁密谐波小,空载定子铁心损耗比径向充磁低约40%;驱动方式对电机损耗尤其是转子损耗影响较大,正弦波驱动时转子损耗几乎可忽略,方波驱动时转子损耗占比可达总损耗的20%。针对方波驱动转子损耗大的问题,在转子表面增加一层铜屏蔽层,分析结果表明可以有效降低转子涡流损耗。对同一台带压缩机负载的高速电机对比测试了2种驱动器控制下的母线输入的有功功率,验证了驱动方式对电机损耗的影响。

High-speed motors have the features of high current frequency,large stator core loss and large rotor eddy loss.The influential factors of core loss and rotor eddy loss are analyzed for the 10 kW,100000 r/min high-speed permanent magnet(PM)motor used in air compressor by comparing the effects of different magnetization methods(parallel and radial)and drive modes[driving by pulse amplitude modulation(PAM)square wave and SiC based pulse width modulation(PWM)sine wave].Finite element analysis results indicate that the air gap flux harmonics of parallel magnetization are smaller,resulting in 40%smaller stator core loss compared with radial magnetization.Drive mode has a significant effect on motor losses especially on rotor loss.The rotor loss driving by sine wave is almost negligible,while it reaches 20%of the total losses when PM moter is driven by square wave because of the current harmonics.For the high rotor loss caused by square wave drive,further analysis is done by adding a copper shield on the rotor surface which can effectively reduce the eddy current loss.A high-speed motor with compressor load is tested under the control by two kinds of drivers to test the input active power on the DC bus.The results verify the influence of drive mode on motor losses.