A new digital controller for a single stage Bi-flyback PFC converter

The single-stage Bi-flyback PFC topology proposed in [1] has several advantages on efficiency, power density and cost. This paper adopts this topology, applying a new digital controller to improve power factor and lower the harmonic distortion. The proposed control structure relies on an adaptive digital algorithm without the need of sampling the input current. Moreover, it can adapt the loop compensation design based on the mode of operation within the line cycle. Such features are absent in present analog controllers, and can overcome the drawbacks of single stage topologies and their control complexity. Derived equations of the Bi-flyback PFC converter are used to implement the controller algorithm in simulation, and verified the feasibility of the proposed control method. A 100W and 20V prototype is used to experimentally verify the controller algorithm performance.