A True Bridgeless Buck-Type PFC Converters with Low Total Harmonics Distortion

Power factor correction (PFC) converters with a diode bridge are extensively used in different AC-DC applications. However, the diode bridge has to employ four diodes to complete the AC to DC at the expense of high conduction losses. Thus, many bridgeless PFC converters have been proposed with dual converter cells to minimize the number of conducted diodes for better efficiency. Unfortunately, these dual-converter cell-based bridgeless converters need almost double components. To solve this issue, this paper proposes a true bridgeless buck-type PFC converter, which annihilates the diode bridge completely with only fewer component counts. The proposed converter uses buck and buck-boost cells to obtain the novel bridgeless topology, which features a simple structure and control to achieve high PF and low total harmonics of input current (THDi). Simulations are given to validate the feasibility of the proposed topology and the control method. Comparisons with the conventional buck PFC converter are also given to confirm the better performances of the proposed topology.