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Totem pole power factor correction rectifiers (TPPFCs) have gained popularity with the advantage of a minimal number of devices for optimal performance, but cause a high output voltage due to the inherent step-up characteristic, limiting the single-stage applications. As the switched capacitor converters (SCCs) feature low voltage stress and high-power density, a hybrid soft-switching step-down power factor correction (PFC) rectifier is proposed in this article, which integrates TPPFC with ladder SCC by redundant switch multiplexing. Similar to the traditional TPPFC, the proposed converter can achieve a unity power factor (PF) and comply with IEC61000-3-2 Class C in universal-input applications. With critical conduction mode (CRM) control, some active switches are turned on and off under soft-switching conditions. Therefore, high-efficiency performance is realized. In addition, an adaptive synchronous timing multiplexing control strategy is presented, achieving low voltage gain and natural capacitor voltage balance characteristics. Finally, a 300-W step-down prototype with 97% peak efficiency and PF of 0.99 is built to verify the theoretical analysis results.

Conventional buck power factor correction (PFC) converter has the disadvantage of high harmonic currents due to the dead zone of input current. An improved method, critical-continuous mode control buck-flyback converter has not completely eliminated the impact of dead zone of buck unit on the input current. In this article, a single-stage integrated buck-flyback PFC converter with low total harmonic distortion (THD) control is proposed and analyzed. With the average current mode control, the input current of each unit can be automatically distributed; therefore, the PFC function with extremely low THD can be achieved. Furthermore, the power ratio of flyback converter unit can be designed to be smaller, thereby improving the system efficiency. The design considerations are analyzed in detail, and the key parameters are designed based on the principle of loss minimization. Finally, a 96-W prototype with a peak efficiency of 95.2% and low THD current is built to validate the proposed converter.