This paper proposed a strategy for fast protection and quick recovery of the FCML PFC under the AC Drop transient. The strategy utilizes comparators for rapid OCP during AC Drop and further avoids overcurrent in the recovery stage via proper duty cycle initialization and soft-start of the current reference. However, the FCVs still oscillate during the recovery process which can roughly be depicted by an ideal state-space model. Based on the oscillation amplitude of FCVs, the safe operating thresholds of the switching devices are provided, some of the switching pairs will undergo more severe overvoltage and require a larger margin of voltage stress. The experiment verified the feasibility of the protection strategy through a 5L totem-pole PFC prototype.
.jpg "Yanqing Wu (he/him/his) photo")