A Digital Controlled of Duty-ratio Feedforward for Four-level Flying Capacitor Boost PFC

This paper proposes a flying capacitor multilevel (FCML) power factor correction (PFC) with phase-shifted pulse width modulation (PSPWM) technology to achieve voltage balance of the flying capacitors and increase the equivalent frequency of the inductor. Under the rated current ripple, a smaller inductance can be used to reduce the size of the inductor. With an FCML architecture design, the voltage rating of the power devices can be reduced, which decreases the switching loss. Based on PSPWM control, the small-signal model is a detailed analysis, and the compensator is designed considering the phase delay caused by digital control. The duty-ratio feedforward (DFF) control reduces the harmonic distortion of the inductor current. Finally, the 350 W four-level flying capacitor boost PFC with DFF control is implemented with an inductor current frequency of 500 kHz, an input voltage of 90-264 Vac, and an output voltage of 390 V.