谐波磁场对双蛙绕组直流电机换向的影响

Impact of harmonic magnetic field on commutation capability of DC machines with double frog-leg windings

双蛙绕组直流电机的绕组结构复杂,影响换向的因素较多,气隙磁场产生的谐波电势对其影响较大。基于双蛙绕组的结构特点及其换向规律,建立了存在气隙谐波磁场情况下的双蛙绕组直流电机换向电路模型,仿真分析了各等效回路的最大电流值。分析表明:增大换向回路的综合电阻可以减小谐波磁场对电机换向的影响、改善电机的换向性能。利用某双蛙绕组电机,使用不同电阻率的电刷,进行了无火花换向区试验。试验表明:在其他条件相同的情况下,选用电阻率大的电刷增大了回路电阻,减小了回路环流,无火花换向区较宽,电机的换向性能较好。

Due to the complexity of the windings structure in double-frogleglike-winding DC electric machinery,there are many factors influencing the commutation of this machinery,among which the dominating one is the harmonic voltage produced by the magnetic field in the slot between the rotor and the stator.Based on the characteristics of this kind of windings and its commutation rules,and the existence of the magnetic field in the slot,the commutating circuit model was established.The maximum current of every equivalent circuit was analyzed by simulation,which shows that after increasing the general resistance values,the influence on the commutation can be decreased and the commutating effects can be improved.Furthermore,the free-spark-commutating-zone experimentation was conducted on a double-frogleglike-winding DC electric machinery,in which many brushes with different resistivity were used.The experimentation shows that supposing the other conditions are all the same,the higher values of the brushes′ resistivity can increase the resistance of the equivalent circuits,and meanwhile,the loop currents value in the equivalent circuits decrease.So,the free-spark-commutating-zone gets wider,and the commutation is improved as well.