从电机设计的角度减少高速永磁电机转子损耗

高速永磁无刷直流电机的转子涡流损耗主要是由定子电流的时间和空间谐波以及定子槽开口造成的气隙磁导变化引起的.转子涡流损耗使电机的效率下降并能引起转子永磁体的退磁.从电机设计的角度，采用解析计算和有限元仿真的方法研究了不同的定子结构、槽开口大小以及气隙长度对高速永磁无刷直流电机转子损耗的影响.利用傅里叶变换，得到了分布于定子槽开口处的等效电流片的空间谐波分量，然后采用计及转子集肤深度和涡流磁场影响的解析模型计算高速电机转子损耗，并对解析计算结果通过有限元仿真加以验证.结果表明，3槽集中绕组结构中含有2次、4次等偶次空间谐波分量，该谐波分量在转子中产生大量的涡流损耗.定子结构对高速电机转子涡流损耗影响很大，合理地设计定子结构能够减小转子涡流损耗.

Reduction of rotor loss in high-speed permanent magnet motors by design method

The rotor eddy current loss in high-speed permanent magnet brushless direct current motors is mainly caused by the space harmonics and time harmonics of armature current and the airgap permeance variation due to slot-openings.Rotor loss reduces the power efficiency and demagnetizes the magnets.From motor design aspect,the influences of various stator structures,slot opening width and airgap length on the rotor loss were studied through both analytical calculation and finite element simulation.The space harmonics of armature magnetic motive force were calculated by current-sheet method and Fourier analysis.Then the rotor loss was derived based on an improved model with the skin depth and the eddy current reaction field taken into account.The results show that 2poles-3slots nonoverlapping motor exhibits high evenorder space harmonics of stator magnetic motive force,and consequently causes much rotor loss.Different stator structures have an impact on the rotor eddy current loss and the rotor loss can be reduced by proper motor design.