变频电动机耦合电容分析与计算研究

Analysis and Calculation of Coupling Capacitance of Variable Frequency Motor

脉宽调制(PWM)变频驱动器在提高交流传动系统效率的同时,产生的高次谐波导致共模电流显著增加。其中电动机定子绕组与定子铁心之间的耦合电容是共模电流的主要通路。准确计算定子绕组与定子铁心之间的耦合电容对于预测共模电流具有重要意义。由于电机绕组内部导线排列不规则,准确进行解析计算较为困难,将其简化为集中导体后,会导致计算精度变差。在绕组全散线模型的基础上,提出了一种简化散线建模方法,能在计算精度不变的情况下,有效地减小模型的复杂度。通过对比解析计算、全散线模型、简化散线模型和测量值,验证了该方法的有效性。

While the pulse width modulation (PWM) variable frequency drive improved the efficiency of the AC drive system,higher harmonics were generated,which caused a significant increase in the common mode current.The coupling capacitance between the stator winding and the stator core of the motor was the main path of the common mode current.Accurate calculation of the coupling capacitance between the stator winding and the stator core was important to predict common mode current.Since the internal windings of the motor were irregularly arranged,it was difficult to accurately perform analytical calculations.Simplifying the internal windings into concentrated conductors may result in poor calculation precision.Based on the full-scattered model of the winding,a simplified-scattered method was proposed.This method could effectively reduce the complexity of the model while keeping the calculation accuracy.The effectiveness of the proposed method was verified by comparing analytical calculations,full-scattered model,simplified-scattered model and measured values.