A low-voltage-gain single-phase hybrid switched-capacitor Boost-PFC circuit and its control method

By adding switching transistors and diodes to the traditional Boost-PFC topology and combining them with a dual-loop voltage and current control method, a single-stage AC-DC conversion and capacitor self-equalization are achieved. This solves the problems of numerous components, complex control, and low efficiency of traditional Boost PFC rectifiers in low-voltage gain applications, and realizes a high-efficiency, low-cost single-stage PFC circuit.

CN122371665APending Publication Date: 2026-07-10HUBEI QINGJIANG HYDROPOWER DEV
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Patent Information

Authority / Receiving Office
CN Β· China
Patent Type
Applications(China)
Current Assignee / Owner
HUBEI QINGJIANG HYDROPOWER DEV
Filing Date
2026-04-30
Publication Date
2026-07-10

AI Technical Summary

Technical Problem

In existing technologies, traditional Boost PFC rectifiers suffer from problems such as a large number of components, complex control, low efficiency, and large size in low voltage gain applications. The two-stage conversion structure increases system cost and complexity, making it difficult to achieve a combination of high efficiency and low cost.

Method used

Design a low-voltage-gain single-phase hybrid switched-capacitor Boost-PFC circuit. By adding a switch and a diode to the traditional Boost-PFC topology and combining it with a dual-loop voltage and current control method, a single-stage AC-DC conversion is achieved. Furthermore, the capacitor self-equalizes voltage through a specific duty cycle and high-frequency switching, eliminating the need for a subsequent DC-DC buck circuit.

Benefits of technology

A single-stage step-down PFC has been implemented, which reduces the number of components, lowers cost and size, simplifies control, and improves system efficiency. It is suitable for low-voltage gain applications such as LED drivers, telecommunications power supplies, battery charging, and motor speed control.

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Abstract

This invention provides a low-voltage-gain single-phase hybrid switched-capacitor Boost-PFC circuit and its control method, belonging to the field of AC-DC power conversion and power factor correction technology. Based on the traditional Boost PFC topology, this invention adds a switching transistor, three fast recovery diodes, and a storage capacitor to form a single-stage low-voltage-gain converter topology, capable of directly outputting a DC voltage lower than the peak value of the AC input voltage, eliminating the need for a subsequent DC-DC buck circuit. The control method employs dual-loop PI regulation of voltage and current, and a dedicated voltage equalization modulation strategy is designed for the dual output capacitors, making the operating frequency of the second switching transistor five times that of the first switching transistor, achieving real-time capacitor voltage equalization without adding hardware. This invention has advantages such as fewer components, simple structure, convenient control, high efficiency, and low cost, and is suitable for single-phase AC-DC conversion applications requiring low voltage gain and high power factor, such as LED drivers, telecommunications power supplies, battery charging, and motor speed control.
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