软开关同步升降压变换器的研究

研究了一种软开关同步升降压变换器。该升降压变换器的滤波电感设计得比较小，使得电感上电流可以反向，分别通过正向电流和反向电流对两个同步整流管的结电容进行充放电，为软开关创造条件。此方法适用于较低压输出、较高功率密度的场合。根据两个开关管实现软开关的务件不同，提出了强管和弱管的概念，给出了满足软开关条件的设计方法。并以一个输入28V、输出20V／3A、开关频率为200kHz的软开关同步升降压变换器的样机进一步验证了上述方法的正确性，其满载效率达到了94．2％。

Research on a Soft-switching Synchronous Buck-Boost Converter

A method for soft switching applicable to Buck-Boost converter is researched. In this converter synchronous rectifier is applied and inductor current is designed to be reverse in every period. Junction capacitance of switch can be charged by reversible inductor current so that soft switching can be achieved. This method is preferable for low voltage output, high power density applications. According to different soft switching conditions, the conception of strong switch and week switch is presented. The design considerations of soft switching condition for strong switch and week switch are also proposed. A 200 kHz prototype of 28V input, 20V output, whose efficiency is 94.2% is built to verify the strategy.