Modeling Single Layer Boost PFC Inductor
In A boost PFC converter, the boost inductor is in the DM noise path so it strongly affects differential mode (DM) EMI noise at high frequencies (HF). The parasitics in the boost inductor makes inductor a complicated network at high frequencies. The HF impedance of the inductor can be modeled using distributed transmission line model. The major parameters used for transmission line structure include turn-to-turn capacitance, turn-to-core capacitance, core loss, winding loss and the inductance of the winding. The permeability is also the function of frequency. The simulated impedance curve using transmission line model can match the measured impedance curve. The transmission line model shows that in order to reduce DM noise at high frequencies, inductor's impedance should be as high as possible at HF. High core loss, low turn-to-turn capacitance; low turn-to-core capacitance can achieve high impedance, therefore low DM noise at HF.