Closed-Loop Control Methods for Interleaved DCM/CCM Boundary Boost PFC Converters

In this paper, a systematic overview of PLL-based closed-loop control methods for interleaved DCM/CCM boundary boost PFC converters is presented. It is shown that the PLL-based closed-loop methods always provide stable operation, unlike the open-loop control methods, where the only method which results in stable operation is the slave synchronization to the turn-on instant of the master with current-mode control. It is also shown that the dynamic response of the PLL-based closed-loop methods with master-slave approach and democratic approach is almost identical. Experimental results obtained on a 300-W, universal input, 400-V output, interleaved DCM/CCM boundary boost PFC prototype circuit with a dedicated controller IC utilizing a democratic, PLL-based closed-loop method is also provided.