两级式三相自然软开关DC/AC逆变器

A Two-stage Three-phase Natural-soft-switching DC/AC Inverter

随着可再生能源并网发电受到越来越多的关注,并网逆变器得到了广泛应用,人们期望并网逆变器在不同负载等级下和宽输入电压范围内实现均能高效率。该文提出一种两级式三相自然软开关DC/AC逆变器拓扑。该拓扑与传统带Boost升压电路的三相逆变器相比,在直流平波电容支路增加了一个辅助开关。通过适当的时序控制可以实现Boost开关管零电压开通,辅助开关工作在全软状态,输出级逆变器软开关次数比传统方案多12.5%。首先分析该种拓扑的工作原理;然后分析第2级电路的具体软化次数;最后,通过10kW样机上的实验验证理论分析。

Since renewable energy generation catches more and more concern,the grid-tied inverters have been widely adopted.These inverters are often expected to work with high efficiency in a broad power range and a wide input DC voltage range.A novel two-stage three-phase natural-soft-switching DC/AC inverter topology was proposed.Compared with the traditional three-phase inverter with a Boost DC/DC input stage,it employs an auxiliary switch in the DC capacitor branch loop.With the correct time sequence control,it can be reached that the Boost switch turns on in zero voltage state,the auxiliary switch achieves fully soft-switching and the soft-switching times of the inverter＇s output stage are 12.5 percents higher than that of the traditional one.The operating principle of this topology was analyzed during different working intervals.The soft-switching times were evaluated.And demonstrative experiments ware performed on a 10 kW prototype to verify the theoretic analysis.