Abstract: In single-phase AC-powered household appliance systems, EMI filters composed of X capacitors and common-mode inductors are typically used to suppress electromagnetic interference, and Boost-type Power Factor Correction (PFC) circuits are employed to improve power factor and reduce current harmonics. However, under certain conditions, the common-mode inductor may experience excessive temperature rise or even overheat and burn out due to current resonance. A high-frequency ripple current equivalent circuit model is established for the EMI filter and Boost-type PFC circuit, revealing the mechanism by which the differential mode component of the common-mode inductor induces current resonance under the excitation of PFC switching ripple current. It analyzes the critical impact of the common-mode inductor's leakage inductance and the X capacitor on current resonance and proposes strategies to reduce the resonance frequency and peak resonance current. Using an inverter air conditioning system as a case study, PSIM simulations and experiments were conducted, which validate the accuracy of the model analysis. A PFC carrier frequency design and common-mode inductor optimization scheme is proposed, thoroughly resolving the reliability issue of common-mode inductor resonance.

Key words: Power factor correction, EMI, Common mode inductance, Resonance