I. Introduction
The advancement of power electronic devices has sparked significant interest in the field of electromagnetic interference (EMI) as well as its associated solutions [1]–[6]. The single-phase common-mode (CM) choke is a critical component in EMI filter to mitigate both conducted [7]–[9] and radiated emissions [10]–[12]. Fig. 1 shows a typical single-phase CM choke that consists of two coupled winding coils wound on a high permeability magnetic core, which imparts a high CM impedance to suppress high-frequency CM currents. Due to the leakage flux, it also induces a differential-mode (DM) inductance, aiding in DM emission attenuation. Besides the CM and DM inductances, the turn-to-turn and phase-to-phase capacitances give rise to parasitic effects that affect the high-frequency performance of choke. With the emerging trend of high switching frequency to achieve highly compact power converters, there is a need for an accurate impedance model of the choke for a wider frequency band so that the EMI filter performance can be predicted and optimized [13]–[16].