辅助电路无储能电容的谐振直流环节软开关逆变器

多数谐振直流环节软开关逆变器在直流母线间串联分压储能电容来为谐振电路提供能量,其缺点是分压电容所形成的中性点电位可能发生变化。针对这个问题,提出了一种新型谐振直流环节软开关逆变器拓扑电路。该拓扑电路不需要在直流母线之间串联储能电容来均分直流电源电压,没有中性点电位的变化问题,提高了软开关逆变器的可靠性,并且辅助电路结构相对简单,有利于降低硬件成本和简化控制策略。详细分析了逆变器在不同工作模式下的工作原理,给出了软开关的实现条件,建立了辅助电路的功率损耗数学模型,并制作了一台3 k W的实验样机,实验结果表明该新型软开关逆变器的开关器件实现了软开关。该新型软开关逆变器能有效降低开关损耗和改善效率。

Resonant DC link soft-switching inverter without storage capacitor in auxiliary circuit

The storage capacitors that divide the voltage of the DC side in auxiliary circuit are used to supply energy to resonant circuit in the most resonant DC link soft-switching inverter.The disadvantage is that the storage capacitors will cause the center tap potential variation problem.Aiming at this problem,a resonant DC link soft-switching inverter topology circuit is proposed in this paper.It avoided the storage capacitors which were used to divide the voltage in auxiliary circuit and there was no center tap potential variation problem,which improved reliability in the inverter.The structure of the auxiliary circuit was very simple,which was conductive to reduce the cost of hardware and simplified control strategy.The operation principle of the soft-switching inverter was analyzed in detail on the basis of equivalent circuits at different operation modes.The conditions for realization of soft-switching were presented.The mathematical model for auxiliary resonant circuit loss was established.A 3kW laboratory prototype was built.The experiment results verified that the switching devices of this soft-switching inverter can realize soft-switching and the soft-switching inverter presented effectively reduces switching loss and improves efficiency.