Study and Implementation of the Passive Snubber with Coupled-Inductor in a Single-Stage Full-bridge Boost PFC

In this paper, an improved passive snubber is investigated in a single-phase single-stage full-bridge boost power factor correction (PFC) converter, by which the voltage spike across primary side of the power transformer can be suppressed and the absorbed energy can be transferred to the output side. Compared with the basic passive snubber proposed earlier, the two single-inductors are replaced by a coupled-inductor in the improved snubber. As a result, the synchronous resonances in the snubber can be achieved, which can avoid the unbalance of the voltage and current in the snubber. The operational principle of the improved passive snubber is analyzed in detail based on a single-phase PFC converter, and the design considerations of both the snubber and the coupled-inductor are given. Finally, a laboratory-made prototype is built, and the experimental results verify the feasibility of proposed method and the validity of the theoretical analysis and design method.