Cascaded Half-Bridge-Based Bidirectional Multilevel Bridgeless PFC With Multioutput Ports
Jun Min, Martin Ordonez
Abstract
Cascaded multilevel power factor correction (PFC) 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 multidc outports with fewer power switches, a cascaded half-bridge-based multilevel multiport bridgeless PFC is proposed in this article. Compared with cascaded full-bridge multilevel PFC, the number of switches per power cell for the proposed PFC is reduced by half while maintaining the same dc outports. Due to the multilevel voltage, the volt–second on the boost inductor decreases, reducing the current ripple of the proposed PFC by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2n$</tex-math></inline-formula> times with the same boost inductance as the conventional totem-pole PFC. By splitting the power into <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2n$</tex-math></inline-formula> cells with low voltage, the total switching losses are also reduced by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2n$</tex-math></inline-formula> times with the same equivalent switching frequency. In addition, 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.