The induced voltage ripple in DC field windings can cause many problems in hybrid excitation machines (HEMs). It can generate ripple current in field winding, thus causing unsteady magnetic field excitation and hence additional torque ripple and losses. Besides, the torque and power density of hybrid excitation machines may be deteriorated as a result of the influence of the induced voltage ripple on field winding's excitation circuit, particularly under high-speed conditions. Based on a hybrid excitation switched flux machine (HESFM), the influence of stator slot and rotor pole number combination on no-load and on-load field winding induced voltage ripples are studied and compared by the finite element method (FEM). It reveals that the harmonic content and thus the peak-to-peak value of the field winding induced voltage ripple are closely related to the stator slot and rotor pole number combination at both no-load and on-load operating conditions. The FEM calculations are verified by experiments on a prototype HESFM.

中文翻译：

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混合励磁开关磁通定子槽和转子极数组合对励磁绕组感应电压纹波的影响

直流励磁绕组中的感应电压纹波会在混合励磁电机（HEM）中引起许多问题。它会在励磁绕组中产生纹波电流，从而引起不稳定的磁场激励，从而导致额外的扭矩纹波和损耗。此外，由于励磁电压纹波对励磁绕组励磁电路的影响，特别是在高速条件下，混合励磁机的转矩和功率密度可能会降低。基于混合励磁开关磁通机（HESFM），研究了定子槽缝和转子极数组合对空载和有载励磁绕组感应电压纹波的影响，并通过有限元方法（FEM）进行了比较。结果表明，在空载和有载运行条件下，励磁绕组感应电压纹波的谐波含量以及峰峰值均与定子槽​​和转子极数组合密切相关。通过在原型HESFM上进行的实验验证了有限元计算。