Cascaded Half-bridge Based Bidirectional Multi-level Bridgeless PFC with Multi Output Ports

Cascaded multi-level PFC (Power Factor Correction) converters show great potential for applications that require high AC voltage input but low DC bus voltage output, such as telecom power supply, battery formation, and Internet data centers. They are compact and put less voltage stress on power switches. To provide multi DC out ports with fewer power switches, a cascaded half-bridge based multi-level multi-port bridgeless PFC is proposed in this paper. Compared with cascaded full-bridge multi-level PFC, the number of switches per power cell for the proposed PFC is reduced by half while maintaining the same DC out ports. Due to the multi-level voltage, the volt-second on the boost inductor decreases, reducing the current ripple of the proposed PFC by $2n$ times with the same boost inductance as the conventional totem pole PFC. By splitting the power into $2n$ cells with low voltage, the total switching losses are also reduced by $2n$ times with the same equivalent switching frequency. Additionally, the proposed rectifier also reduces conduction losses as lower voltage switches with smaller conduction loss are adopted in half-bridge cells compared with conventional totem pole PFC rectifiers. Finally, these benefits are analyzed and validated with experiments.