传统的降压型功率因数校正（power factor correction，PFC）变换器由于存在高谐波电流的缺点，较难满足IEC61000-3-2 C类限值，其应用受到很大限制。文中设计并搭建了一种集成式功率因数校正变换器，该变换器由一个降压PFC变换器和一个反激PFC变换器组成，其中降压和反激PFC变换器采用输入并联和输出并联连接方式共用一个GaN开关管和控制电路，降低变换器成本。集成式变换器在临界导通模式（critical conduction mode，CRM）恒定导通时间（constant on time，COT）控制下，反激单元消除了降压输入电流死区的影响，利用降压和反激PFC变换器的优势和GaN开关管的优异性能，变换器可以在宽电压输入范围下实现高效率和低总谐波失真。文中介绍了电路结构和工作原理，通过PSIM（power simulation）仿真验证理论推导的正确性，最后搭建了满载效率为94.1%的120 W样机，验证了该方案的可行性。

Conventional buck power factor correction(PFC) converters suffer from the drawback of high harmonic current, making it challenging to comply with the IEC61000-3-2 Class C limits and limiting their applications. This paper presents and analyzes a single-switch integrated buck PFC converter. The converter is composed of a buck and flyback PFC converter in an input-parallel-output-parallel connection structure. Only one GaN switch and its control circuit are used, reducing the converter’s cost. With critical conduction mode constant-on-time control, the effect of the dead zone of the buck input current is eliminated by the flyback unit. Taking advantages of the buck and flyback PFC converters and the excellent performance of the GaN switch, the converter achieves high efficiency and low total harmonic distortion over a wide voltage input range. This paper introduces the circuit structure and working principle. The theoretical derivations are validated using PSIM simulation software. Finally, a 120 W prototype with 94.1% peak efficiency is built to verify the analysis results.

TM461

国家自然科学基金资助项目（61974056）；江苏省重点研发计划-社会发展资助项目（BE2020756）。