无源器件辅助换流的单相全桥软开关逆变器

Single-Phase Full-Bridge Soft-Switching Inverter with Passive Device-Assisted Commutation

为提高单相全桥逆变器的转换效率,提出了一种无源器件辅助换流的单相全桥软开关逆变器拓扑结构,通过在逆变器桥臂上增加辅助谐振电路,实现了开关器件的软开关动作.辅助谐振电路中无辅助开关器件,只含有电感、电容和二极管等少量无源器件,这有利于降低辅助电路的成本,而且不会使逆变器的控制策略复杂化.此外,在逆变器处于死区状态时,负载电流能通过辅助谐振电路续流,可以改善逆变器输出电流波形的畸变率,减小了死区的不利影响.文中详细分析了电路的工作过程,在功率为4kW的单相实验样机上进行了实验验证,获得的实验结果表明在轻载和满载时逆变器的开关器件都能实现软开关,逆变器输出电流波形的畸变率都得到了改善.因此,该无源器件辅助换流的单相全桥软开关拓扑结构对于提高逆变器的性能具有重要意义.

A single-phase full-bridge soft-switching inverter with passive device-assisted commutation is proposed to improve conversion efficiency of the single-phase full-bridge inverter.The soft-switching action of the switch devices is achieved by adding an auxiliary resonant circuit to bridge arms of the inverter.There is no auxiliary switch device in the auxiliary resonant circuit but few passive devices such as inductances,capacitances,diodes,and so on,which is helpful to reduce the cost of the auxiliary circuit and can’t complicate the control strategy of the inverter.In addition,freewheeling of load current can be realized via the auxiliary circuit and the distortion ratio of output current waveforms of the inverter is reduced when the inverter is in the dead state,which reduces the effect of dead-time on the output current of the inverter.The operation process of the circuit is analyzed in detail.The experimental verification is carried out on a 4kW one-phase laboratory prototype.Experimental results verify that the switch devices of the inverter can achieve soft-switching in both light load and full load,the distortion ratio of output current waveforms of the inverter is improved.Therefore,the single-phase full-bridge soft-switching topology with passive device-assisted commutation has an important significance for improving the performance of inverter.