一种快速准确计算共模扼流圈动态电感的方法

A Fast and Precise Method for Calculating Dynamic Inductance of Common Mode Chock

共模扼流圈是通信线或电源滤波的重要组成部分,其对共模干扰信号的抑制起关键作用。实际应用中,扼流圈内同时存在差模电流和共模电流,当差模电流较大时,不同数值的差模电流致使磁心不同程度的饱和,对应磁化曲线工作点进入非线性区,从而使得共模动态电感数值减小、扼流圈共模干扰抑制能力降低。为快速、准确计算非线性情况下动态电感以评估扼流圈干扰抑制能力,根据场量对称关系建立共模扼流圈简化模型,通过有限元方法计算并提取不同差模电流下线圈电流与磁链的关系,利用Simpson数值微分公式计算磁心不同饱和程度下共模扼流圈动态电感。结果表明:所建简化模型相对全模型计算速度提升4～5倍,同时相比传统向前差商法或中心差商法,其计算结果稳定性高、精度高。

Common mode choke is an important part of telecommunication system or power filter,which plays key role on the inhibition of common mode interference.There are both differential mode current and common mode current in the choke coil in practice.When the differential mode current value is pretty large,different values of the differential current will cause the core to be saturated in different degrees,and the corresponding operating point on magnetization curve will enter the nonlinear region,which will decrease the common mode dynamic inductance value and thus reduce suppression ability of common mode chock.In this paper,in order to quickly and accurately calculate the dynamic inductance in the nonlinear case for evaluating interference suppression ability,an simplified model of common mode choke is established basing on electromagnetic field symmetry,and the relationship between current and flux in the coil under different differential mode current is obtained from finite element method.Simpson numerical differential formula is used to calculate the common mode choke dynamic inductance under different saturate degrees of core.The results show that the simplified model in this paper is 4~5 times faster than that of the existing model,and the calculating stability and accuracy of dynamic inductance for the common mode choke is higher than traditional method.