A Broadband Accurate Modeling Method for Amorphous Common-mode Chokes and Its Application
Due to the characteristics such as high saturation magnetic flux density and high magnetic permeability,common-mode chokes with amorphous cores are widely used in various switching power supplies to suppress electro-magnetic interference(EMI).Unlike ferrite common-mode chokes,the frequency dependence of the magnetic permeability of amorphous common-mode chokes is stronger,making its accurate modeling more difficult.A high-order model consisting of a basic RLC resonant circuit with three parallel RL branches was proposed based on admittance analysis for the common-mode paths of amorphous common-mode chokes.On this basis,a full circuit broadband model for amorphous common-mode chokes including both common-mode and differential-mode parameters was established.A method for obtaining model parameters by combining impedance calculation of characteristic point with numerical fitting was provided.The Simulated and measured results verified that the model has high accuracy in the wide frequency range of 100 kHz～100 MHz,with common-mode impedance error less than 1 dB.Finally,the model was applied to EMI prediction of a push-pull converter,reducing the simulation error of the EMI filter's common-mode insertion loss from 100 kHz to 10 MHz.The measured and simulated common-mode spectrum have good consistency from 150 kHz to 30 MHz,which indicates the effectiveness of the high-order model.
common-mode chokeamorphouselectro-magnetic interference(EMI)switching power supplycommon-mode noise
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维普
