| With the development of high frequency and high power density of switching power supply,the high frequency performance and electromagnetic compatibility performance of the device are badly affected by its parasitic parameters.As a component of high frequency switching power supply,magnetically enhanced printed circuit board(PCB)planar inductor and transformer is of great significance to accurately establish its high frequency model in the early stage of design.Although electromagnetic simulation software like ANSYS can analyze hybrid electromagnetic structures,it is difficult to provide circuit models with direct physical significance for designers.Partial Element Equivalent Circuit(PEEC)can model passive devices in high frequency.However,it is still difficult for PEEC to model the nonlinear lossy magnetic medium at present.With magnetically enhanced planar inductance and transformer inductive device as the research object,this dissertation will carry out the research on PEEC modeling derivation with lossy magnetic medium,PEEC modeling and circuit model order reduction of magnetically enhanced planar inductor and transformer.Based on volume equivalence principle,this dissertation establishes PEEC model of magnetic medium.The PEEC model of the magnetic medium is established by discretizing the magnetic medium into free space including conductive current source,polarized current source,magnetized current source and polarized charge source,and transforming the magnetic medium unit into corresponding resistance,polarized capacitance and magnetic boundary fluidic coefficient.The potential difference equation of body current branch,current equation of potential node,current coupling equation of magnetic surface and port impedance equation are derived.Further,the integral equation of PEEC model of hybrid electromagnetic structure is established.For the regular geometric structure,the numerical formula suitable for MATLAB programming is deduced.A wide frequency domain PEEC model is established for two specific structures of magnetically enhanced planar inductors and transformers.By dissecting and dispersing the conductors,dielectrics and magnetic media of device,the equivalent circuits of each part are obtained,and then the complete PEEC model and port impedance characteristics of device are obtained as wellaccording to the electromagnetic relationship between the parts.The experimental results of port impedance characteristics verify the effectiveness of the proposed method.According to the relationship between the resonant frequency of device and the parameters of circuit elements,the PEEC model reduction method based on the resonant frequency of the circuit network is studied.The simplified,intuitive and physically meaningful equivalent circuit of device is obtained by reasonably reserving the low frequency resonance points,and the error of the simplified model and the applicable frequency band are analyzed.The feasibility of the PEEC model reduction method is verified by the measured impedance characteristics of the devices.The PEEC modeling theory with lossy magnetic medium is developed in this dissertation,establishes the PEEC model of magnetically enhanced inductive devices and expands the model reduction method based on characteristic frequency,which will have certain theoretical reference value for PEEC modeling of magnetic devices. |
