一种高效PWM变换电路的研究

ＰＷＭ（Ｐｕｌｓｅ－Ｗｉｄｔｈ－Ｍｏｄｕｌａｔｉｏｎ）变换电路中，可控开关在每次通断过程中要承受高的开关压力与高的开关损耗，而且该功耗会随着ＰＷＭ开关频率的增加而线性地增加．减小开关损耗最有效、最直接的方法是采用软开关技术．文中提出了一种最新的电路拓扑结构，采用综合零电压技术与零电流技术的软开关技术，应用于升压式ＰＷＭ变换电路，使ＰＷＭ变换电路的开关，既能在零电压下实现开通，又能在零电流下实现关断，从而大大减小开关损耗，可显著地提高电能转换效率．同时提出了一种实用的控制电路，不仅电路结构简单，而且容易保证三路开关信号的时序关系（输入一路波形，同时输出三路波形，控制三个开关管）．输出波形完全能反映输入波形的变化．该设计思想对ＰＷＭ变换电路的进一步研究有着积极的意义．

Investigation on High Efficiency PWM Converters

The soft switching technique is a most effective and direct method to decrease the switching power losses. This paper presents a novel soft switching topology and proposes a control method combining both zero voltage transition and zero current transition techniques in the circuit. The converter can really achieve the zero voltage switching on and zero current switching off for all the switching transistors so as to decrease the switching losses and increase the efficiency of the circuit markedly. A useful control circuit is also advanced in the paper,which has a simple structure and can easily assure the sequence in time on three switching signals. And three output waves is from one input wave only to control three switch tubes. The output waves can change just the same as the input wave. As a new design idea, this technique will play a positive role in the future study on the convert circuit with PWM.