Research On Planar Passive Integrated EMI Filter Based On 3D Printing Technology

Because of more frequent switching action of Power Converter.Electromagnetic interference(EMI) becomes a problem that can't be ignored.To suppress the EMI,EMI filter is used between the power line and the input of converter.However,for conventional discrete EMI filters,its large volume and low space utilization decrease the power density of SMPS;In order to reduce the size of the EMI filter, to shorten cycle time of production,to reduce costs of model,to increase power density,to solve the difficulty about producing complex model and other issues,3D printing is proposed to achieve planar magnetic integrated EMI filter technology;This paper presents two different structures of magnetic integrated EMI filter, the correctness and accuracy of the structure is validated through deriving an easy and effective mathematical model for calculation of inductance,combining with 3D finite element simulation,saber simulation method;Through the establishment of a simple simulation circuit,compared graph of insertion loss,making use of the technology to produce EMI filter has good filter performance.In order to further reduce the size of EMI filter and improve the power density of switch mode power supplies,the elliptic planar L-C coil structure is proposed in this paper. The finite element simulation of the rectangle and elliptic planar L-C coil is done, by comparing the characteristics between them,the elliptic planar L-C coil is used as the basic EMI filter unit and planar passive EMI filter is achieved based on this structure. The high-frequency common-mode equivalent circuit model is established taking into account the EPC(Equivalent Parallel Capacitance) of common-mode inductance and the ESL(Equivalent series inductance) of common-mode capacitor and their ESR(Equivalent series Road).The insertion loss formulas are deduced with "A" parameter matrix of two-port network.By analyzing the proximity effect loss formula to determine the PCB copper foil thickness,it can minimize the losses.By the simulation and experimental analysis,The correctness of the proposed structure and its high-frequency common-mode equivalent circuit model and insertion loss formulas are demonstrated.