一种新颖的单端DC/DC开关式变换器

A New Single-Ended DC/DC Switching Converter

本文讨论了一种新颖的单端DC/DC开关式组合变换器。它由一个正激变换器和一个反激变换器组合而成。利用正激和反激变换器各自的工作特点,采用了原边串联,副边关联的组合形式、结果,在整个开关周期内均有能量从原边传送给负载。同时,也使输出电流频率增大,纹波减小,从而减小了输出滤波器的尺寸。另外,在电路中使用了LCD无损吸收网络,以保护开关功率管,并实现变压器铁芯的磁通复位,使部分能量返送回输入电源,减少了开关损耗,提高了整体效率. 本文分析了该变换器的一般工作原理,推导出了主要参数的设计准则。结果表明,通过合理的参数设计,可使输出电流纹波很小。对中等功率、高频、要求高效率的场合,这是一种比较适宜的单端交换器。

A new single-ended DC/DC switching converter is discussed in this paper. This converter consists of a forward converter and a fly-buck converter. They are in series on the primary windings and parallel on the secondary windings, and share the same switching element. Therefore, the energy is always transmitted from the primary winding to the load continuously, in the whole switching period. At the sametime,the frequency of the output current is increased,the ripple reduced,and the size of the filter also reduced. Besides,in order to reduce the switching loss and to assure reliable operation,a nondissipative snubber is specifically used. Therefore,it has some distinctive characteristics as compared with the general single-ended converters.The general operating principle of this converter is analyzed,and the primary design criterion of its main parameters is presented. The result shows that the ripple of the output current will be quite small with properly designed parameters. It is a novel converter of high efficiency and medium power.