计及寄生参数效应的铁氧体共模扼流圈二端口网络的建立

计及寄生参数效应的铁氧体共模扼流圈二端口网络的建立:共模扼流圈的寄生参数在高频时对滤波器的性能有重要影响，准确建立其对应的差模和共模二端口模型
对设计电磁兼容滤波器以及改善其性能具有重要意义。对差模电路，通过建立静电场模型并计算匝间部分电容可得到等效寄生电容，进而获得二端口内各支路的电容参数；测量其谐振频率，可得到差模漏电感。对共模电路，通过建立时谐磁场模型，采用类比有限元法可求解磁芯等效电感和电阻；测量其谐振频率，可得到考虑环境因素后的寄生电容。测量扼流圈二端口在输入、输出匹配状态下的散射参数，间接得到滤波器差、共模电路对应的二端口网络各支路的阻抗或导纳。散射参数法的测试与“谐振频率＋有限元法”建立的阻抗取得较好地一致，说明模型的准确性和测试方法的合理性。
Abstract: Because of the effects of parasitic couplings of choke playing important roles in the high frequency
performance of EMI filters, it is necessary to construct the 2-port network models corresponding to the CM and DM circuits
for designing EMI filters and improving their performances. For the equivalent DM circuit, the partial capacitances of turn to turn and more the equivalent parasitic capacitance can be calculated by setting up the electrostatic model. Further, capacitive parameters in each branches of 2-port for CM are obtained. The DM leakage inductance can be achieved if the resonant frequency is measured. For the equivalent CM circuit, equivalent magnetic core resistance and inductance can be solved using analogical finite element method (FEM) by setting up the model of harmonic magnetic field. The parasitic capacitance considering the environmental factor can be achieved if the resonant frequency is measured. To measure the scattering parameters under the input and output matching state for choke, the branch impedances or admittances of DM and CM models are achieved indirectly. The impedances of branches using scattering parameters measurement are in good agreement with the ones using ‘resonant frequency adding FEM’. It was demonstrated that the veracity of setting models and the rationality of measuring method.
关键词﹕扼流圈 差模电路 共模电路 有限元法 散射参数 谐振频率
Keywords: Choke, differential model circuit; common model circuit; finite element method (FEM); scattering
parameters; resonant frequency