High-Frequency Modeling of Common-Mode Chokes Based on the Identification of Frequency-Varying Parameters

To overcome the disadvantage of impedance measurement which is influenced by parasitic parameters and non-ideal characters of conductor lines as well as cannot perform the frequency-varying parameters. This paper presents a high-frequency modeling method of common-mode chokes based on frequency-varying parameters. A high-frequency lumped parameter model was built, which included winding inductances, leakage inductances, parasitic capacitances between and in the windings, equivalent resistances of magnetic cores and copper losses. Using traditional least-square method, the forgetting factor and rectangular window was introduced to estimate the frequency-varying parameters. The mean square convergence of this method is proved. The modeling method proposed in this paper is proven accurately by comparing the experimental result with simulation result between 150 kHz-30 MHz. The restraining effects are best at the resonance frequency of the common-mode choke. In addition, an experiment is conducted to verify the conclusion by restraining the electromagnetic interference produced by a switching circuit.