基于双辅助网络的宽软开关范围高效高频链DC-AC变换器

Wide-range Soft-switching High-efficiency High-frequency-link DC-AC Converter Based on Dual Auxiliary Network

该文提出一种基于双辅助网络(dual auxiliary network,DAN)的宽软开关范围周波变换类型的高频链逆变(cycloconverter-type high frequency link inverter,CHFLI)电路,简称DAN-CHFLI电路。原边侧采用对称型无源辅助网络(passive auxiliary network,PAN)解决了传统CHFLI电路在空载、轻载及输出电压较小时原边侧开关管无法实现软开关的问题,拓宽了软开关范围,保证了其在任意负载条件下的零电压导通(zero voltage switching,ZVS)。副边侧有源辅助网络(active auxiliary network,AAN)由钳位电容和H桥组成,可以解决漏感与开关管寄生电容谐振造成的电压振荡问题,并辅助周波变换器换流。针对AAN电路,提出一种移相钳位策略:AAN开关管与原边开关管类似,也采用固定占空比方波信号移相调制;且相比原边开关管,AAN开关管延迟导通以实现软开关。文中详细分析了DAN-CHFLI拓扑结构、换流过程、PAN和AAN工作原理及开关管的软开关特性,并设计实验样机验证了理论分析的正确性。

A wide-range soft-switching cycloconverter- type high-efficiency high-frequency-link inverter （CHFLI） based on dual auxiliary network （DAN） was proposed. The primary-side passive auxiliary network in DAN-CHFLI provides enough reactive current and extends soft-switching range, achieving zero voltage switching （ZVS） for primary-side full-bridge switches under different operating conditions from light load to full load. The secondary-side active auxiliary network （AAN） with power switches and clamping capacitor is utilized to assist commutation and eliminate the voltage spikes caused by the leakage inductor of high-frequency transformer. A novel phase shifted clamping strategy for the AAN was proposed. All switches of AAN are driven with nearly 50% fixed duty cycle square signals, thus making gate driving circuits for power switches easy to realize. Compared with primary-side fidl-bridge switches, the switches of AAN conduct with delay time but turn off synchronously. The delay time maintains ZVS turn-on of AAN switches. The modulation strategy, detail operation principles and soft switching characteristics of DAN-CHFLI were analyzed and derived. Finally, experimental results were presented to verify the analysis results.