提出一种新颖的单级式推挽高频链逆变器拓扑,变压器初级侧采用电源端串接一个开关管的三管推挽结构,次级侧采用双绕组全波式周波变换器结构。该类逆变器具有拓扑简洁、初次级开关管均可在宽输出电流区间范围内实现零电压开通、变换效率高等优点。电路采用正弦脉宽脉位调制策略,变压器初级侧辅助开关管的工作频率是另外2个开关管的2倍,除去死区时间,辅管的驱动信号逻辑上是另外2个开关管驱动信号的与非关系。详细分析了各工作模态,讨论了次级占空比丢失、软开关实现条件及特殊变压器设计的关键电路参数设计准则等。最后,制作了一台输入40~60 V DC、输出110V AC、额定功率660 W的原理样机,实验波形及较高的变换效率验证了所提拓扑的正确性。
A topology of single-stage push-pull high-frequency link inverter is proposed. The primary side of its transformer adopts a three-transistor push-pull structure with a switching transistor connected in series to the power source while the secondary side of its transformer adopts two-winding full-wave cycloconverter topology. With simple topology and high conversion efficiency,the proposed inverter realizes the zero-voltage turn-on of all transistors within a wide output current zone. It adopts the sine pulse width and position modulation strategy. The operating frequency of the auxiliary switching transistor at the primary side of its transformer is two times the frequency of other two transistors. Except for the dead-time,the driving signal of the auxiliary transistor is logically the NAND of the driving signals of other two transistors. Different operating modes are analyzed in detail. The secondary-side duty-cycle loss,the conditions for realizing softswitching and the parameter design criteria of key circuits for special transformer and so on are discussed.An inverter prototype with 40~ 60 V DC input,110 V AC output and 660 W rated power is built,the experimental waveforms and high efficiency verify the correctness of the proposed topology.