Novel Embedded Back-to-Back Five-Level PFC Rectifiers Based on Simplified Current Path

In this article, a family of embedded back-to-back single-phase bridgeless five-level power factor correction (BTF-PFC) circuits is proposed. The switches are connected in reverse-series on the ac side to form a back-to-back structure, reducing control complexity. Switch units are embedded between the bridge arms and the midpoint of the split capacitor to achieve a five-level output. Current path simplification is employed to optimize the bidirectional switches embedded in the unit, while maintaining circuit stability and low voltage stress. First, the characteristics of the circuits are analyzed and compared, with BTF-PFC-II taken as an example to illustrate the operating principle in detail. Second, proportional integral (PI) dual-loop control is employed to ensure sinusoidal induction current, and in-phase carrier stacking SPWM modulation is adopted. The SPWM method achieves five-level rectification by simply adjusting the pulse distribution, simplifying pulse debugging. Finally, an experimental prototype with a rated output of 1 kW/400 V is built, and experimental results are presented to validate the performance and effectiveness of the proposed topologies.