The four-switch flyback (FSF) converter features low voltage stress of the power switches and zero-voltage-switching (ZVS). In this article, the clamp capacitance is properly designed to avoid multiple meeting points of the leakage inductance current and magnetizing current. Then, a pulse width modulation (PWM) plus voltage-second balance (VSB) control is proposed to turn OFF the clamp switch to guarantee the negative magnetizing current for realizing ZVS, and the secondary rectifier current sensor is not necessary anymore. The principle of the FSF converter is analyzed, the design considerations are provided, and the implementation of the proposed PWM plus VSB control is given. Finally, a 60-Wprototype operating at 500 kHz using GaN devices is built and tested in the lab. The experimental results are provided to verify the effectiveness of the proposed control scheme.

中文翻译：

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ZVS 四开关反激式变换器的 PWM 加压秒平衡控制


四开关反激式 (FSF) 转换器具有低电源开关电压应力和零电压开关 (ZVS) 功能。本文中，钳位电容经过适当设计，以避免漏感电流和磁化电流的多个交汇点。然后，提出了脉宽调制（PWM）加电压秒平衡（VSB）控制来关断钳位开关，以保证实现ZVS的负磁化电流，并且不再需要次级整流器电流传感器。分析了 FSF 转换器的原理，提供了设计注意事项，并给出了所提出的 PWM 加 VSB 控制的实现。最后，在实验室中构建并测试了使用 GaN 器件在 500 kHz 下运行的 60 W 原型。实验结果验证了所提出的控制方案的有效性。