High-Frequency Impedance Modeling of Nanocrystalline Common-Mode Chokes Using Mixed-Mode Theory and Improved Multistage RLC Iteration Circuit

The common-mode choke (CMC) serves as a key component in mitigating electromagnetic interference noise across various applications. High-frequency (HF) impedance modeling of CMCs is essential for estimating their performance, typically involving two parts: impedance characterization and behavioral modeling. This article proposes a method for HF impedance modeling of single- and three-phase nanocrystalline CMCs, employing mixed-mode theory and improved multistage RLC iteration circuit. For impedance characterization, the initial step involves constructing 3D numerical models of CMCs to extract their scattering (S-) parameters prior to the fabrication of CMCs. Following this, impedance information of CMCs is derived from the simulated S-parameters utilizing network analysis and mixed-mode theory. Compared with traditional numerical methods, the proposed method achieves rather high accuracy in determining both the magnitude and phase of common-mode and differential-mode impedances for single- and three- phase CMCs while offering ease of implementation. Leveraging the derived impedance information, an improved multistage RLC iteration circuit is developed for behavioral modeling. It accounts for the frequency-dependent permeability of the nanocrystalline core, determining the RLC stages based on the degree of frequency dependence. Experimental cases validate the capability of the proposed method for HF impedance modeling of single- and three-phase nanocrystalline CMCs.