Research On The Broadband PEEC Model Of The Inductive Devices Of Switching Mode Power Supply

With the development of switching mode power supply in the direction of high frequency and high power density,the parasitic parameters of devices and the problems of electromagnetic interference caused by them a re becoming more and more obvious.The magnetic devices,such as inductor and transformer,which are made of ferrite material,are important parts of the switching mode power supply.It is an indispensable part of the switching mode power supply simulation to build an accurate circuit model for them.In power electronic inductive devices,electric field and magnetic field are closely coupled.Therefore,it is necessary to combine different engineering disciplines such as circuit,electromagnetic field and computational electromagnetics to get better model effect.The partial element equivalent circuit(PEEC)is a kind of modeling method which combines circuit and electromagnetic field theory organically.The circuit model with physical significance is very suitable for the field of power electronics.At present,there are still some technical challenges in the application of PEEC in the modeling of magnetic materials.In this dissertation,the toroidal inductor and PCB plane inductor with closed ferrite core in switching power supply are studied,and the PEEC method is used to study the broadband model of magnetic devices.Firstly,the conductor and magnet parts of the device are discretized.According to Maxwell's equations under the equivalence of free space of homogeneous medium,the source area of the medium space is discretized into conduction current source and additional polarization current source,magnetization current source and polarization charge source which meet the boundary conditions.Secondly,by using the definitions of partial resistance,partial inductance and partial capacitance,the electromagnetic field problem is transformed into the corresponding circuit problem,and the overall equation of PEEC model of mixed electromagnetic structure i s obtained.In the PEEC model including magnetic materials,the port impedance characteristics of magnetic devices are derived by combining the mixed potential integral equation with Kirchhoff's current law(KCL)and Kirchhoff's voltage law(KVL).According to the rules of mesh generation,the orthogonal and non-orthogonal geometric elements are obtained.Based on the position information of each element and the corresponding numerical calculation formula,the parameters of each element are calculated,and then a complete PEEC model is established.Finally,a program is written to solve the model,and the calculated port impedance characteristics of the toroidal inductor and PCB plane inductor are compared with those of the actual test and HFSS simulation.The results show that in a wide frequency band,the impedance characteristic curve is consistent well,which verifies the validity of PEEC method in modeling of magnetic medium.In this dissertation,the broadband model of PEEC for the inductive devices of switching mode power supply is established,and the modeling of the toroidal inductor including magnetic materials is realized by PEEC method.And the PEEC model is applied to the study of PCB planar inductors.This study provides an effective reference for electromagnetic analysis and modeling technology in switching mode power supply.