Abstract:The EMI filters are important components to suppress interference, the high-frequency performance of which suffers from the parasitic parameters of discrete components. The parasitic parameters can be cancelled with the methods of negative parameters, including negative inductance and capacitance. The negative inductance and capacitance are obtained using two in-plane coupled inductors and inductor linked a capacitor to ground at middle node, respectively. In order to reduce the impact of secondary capacitance effectively, a new type of planar eliminator using PCB windings and the inductor with bifilar windings in series are designed in this paper. The former is a circular coil consisted of PCB wires staggered in the board’s upper and lower levels, and the mutual inductance is calculated by 3D finite element model, which provides a numerical method for the design of such eliminator; the latter is achieved through a capacitor connected between the ground and the intermediate nodes of coil which coupling coefficient is closed to one. If a capacitor whose value is times parasitic capacitance is linked to ground at middle node with high coupled winding, the first and secondary parasitic capacitance of inductor can be eliminated effectively. Finally, such planar eliminator and the inductor with bifilar windings in series for parasitic parameters cancellations are applied to the EMI common filters and applicable design rules are established and experimentally validated.
王世山, 朱叶, 崔永生. 基于“负参数”理论的EMI滤波器寄生参数的双重消除[J]. 电工技术学报, 2011, 26(10): 181-187.
Wang Shishan, Zhu Ye, Cui Yongsheng. Dual-Cancellation of Parasitic Parameters Based on Theorem of Negative Parameters for EMI Filters. Transactions of China Electrotechnical Society, 2011, 26(10): 181-187.
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