Cascaded Half-bridge Multi-Level Multi-Outputs Bridgeless PFC

Nowadays, there has been increasing demand for higher power density Power Factor Correction (PFC) rectifiers. The large volume of the boost inductor remains the dominant challenge for further improving the power density of bridgeless PFC topologies. To reduce the size of the inductor and provide multi dc outputs, a half-bridge based bidirectional multi-level bridgeless PFC is proposed in this paper. Compared with the cascaded full-bridge multilevel rectifier, the number of switches per cell for the proposed topology is significantly reduced by half while maintaining the same DC out ports. Thanks to the decrease of volt-second on the boost inductor brought by multilevel voltage, the required inductance can be shrunk by N-2 times compared with conventional two-level PFC rectifiers with the same current ripple. By splitting power into cells with low voltage, the total switching losses reduce with 1/N cells under the assumption of the equal equivalent switching frequency. Moreover, the conduction losses can also benefit from the proposed rectifier as the lower voltage switches with smaller conduction loss are adopted in half-bridge cells compared with two-level PFCs. Finally, these benefits are analyzed and validated.