中文说明：应用背景提高电力电子装置的效率、减小装置的体积是电力电子技术的主要研究内容。提高开关频率是减小变压器、滤波器体积的有效手段，但由于电力电子器件在开关过程中存在电压与电流的重叠部分，存在开关损耗和开关噪声，硬开关电路随着开关频率的提高这些问题变得更为严重。软开关技术通过在电路中引入谐振改善了开关的开关条件，在很大程度上解决了这两个问题。关键技术移相全桥型零电压电路是零电压开关PWM电路中具有代表性的电路，具有十分广泛的应用。同硬开关全桥电路相比，电路并没有增加辅助开关元件，而是仅仅增加了一个谐振电感，就使电路中四个开关器件都在零电压的条件下开通，这得益于其独特的移相控制方法。在超前桥臂关断时，利用谐振电感和输出滤波电感与器件的并联电容进行谐振，实现器件的零电压开通；当滞后桥臂关断时，仍利用谐振电感和器件并联电容进行谐振实现器件的零电压开通。器件的两端电压、电流没有明显的过冲。但由于超前桥臂和滞后桥臂参与谐振的电感不同会造成滞后桥臂实现软开关较为困难。
English Description：
Application backgroundImproving the efficiency of power electronic devices and reducing the volume of the device are the main research contents of the power electronic technology. Increasing switching frequency is an effective method to reduce the volume of the transformer and filter, but because of the overlap of voltage and current in the process of power electronic devices, there is a serious problem of switching losses and switching noise. Soft switching technology has solved these two problems in a large extent by the introduction of the resonance in the circuit to improve the switching condition of the switch.Key TechnologyThe phase shifted full bridge zero voltage circuit is zero voltage switching circuit representative in PWM circuit, which is widely used. Compared with the full bridge circuit, the circuit does not increase the auxiliary switching element, but only increases the resonant inductance, and the four switching devices in th