飞轮储能用高速永磁电机转子的涡流损耗

为了减小高速永磁电机中由定子电流的时间谐波、定子磁动势的空间谐波以及定子槽开口造成的气隙磁导变化引起的转子涡流损耗,提高电机的效率,采用ANSOFT有限元软件分析了高速永磁电机中气隙磁场和定子电流.研究了槽开口大小以及气隙长度对转子涡流损耗的影响,分析了利用涡流磁场的屏蔽作用，提出在永磁体外增加一薄层非导磁金属屏蔽环来减小转子铁心、永磁体和护套损耗的机理和有效性,以及屏蔽环的电导率和厚度对转子涡流损耗的影响.结果表明：在合理选取槽开口大小、气隙长度和非导磁金属屏蔽环电导率和厚度的情况下,添加非导磁金属屏蔽环可以有效地减小转子涡流损耗.

Rotor eddy current loss in high speed permanent magnet motors for flywheel energy storage system

In order to reduce the rotor eddy current loss, which is mainly caused by temporal harmonics in the excitation current, spatial harmonics in the pulsating stator magnetic motive force, and the airgap permeance variation due to slot openings, and improve the efficiency of high speed permanent magnet motor, the spatial harmonics of the airgap flux density and the temporal harmonics of the excitation current were first analyzed by ANSOFT software, The influences of slot opening width and airgap length on the rotor eddy current loss were studied considering the skin effect. The mechanism and the effectiveness of a thin unmagnetized metal shielding ring around the magnets, which uses the shielding effect of the eddy current magnetic field, to reduce the eddy current loss in the rotor core, the magnets, and the retaining sleeve were analyzed. The effects of the electrical conductivity and thickness of the shielding ring on the rotor eddy current loss were analyzed. The results show that a thin unmagnetized metal shielding ring around the magnets only with a properly chosen slot opening width, airgap length, electrical conductivity and thickness of the shielding ring can significantly reduce the total eddy current loss of the rotor．