单相并网LCL型逆变器的改进设计方案

随着越来越多的分布式能源接入电网,并网逆变器获得了更多的应用。并网逆变器能够成功实现并网运行的前提是其直流母线电压高于最小要求限值,这限制了并网逆变器的应用。为降低并网逆变器的应用门槛,提出一种单相并网LCL型逆变器的改进设计方案。该设计方案通过将LCL型滤波器设计成一个有一定升压增益的模块,降低了前端逆变桥的输出电压要求,进而能够降低并网逆变器的直流母线电压限制,扩大了单相并网逆变器在低功率场合下的应用。首先分析传统LCL型单相并网逆变器直流母线电压受限制的原因,然后基于一种改进LCL型滤波器设计思路,利用其电压增益功能,给出一种详细的单相并网LCL型逆变器的改进设计方案,最后通过仿真和实验验证了提出的设计方案的有效性。

A New Design of Single-Phase Grid-Connected LCL Type Filter Inverter

With more and more distributed energy accessing to the power grid, the grid-connected inverter has gained more applications. The grid-connected inverter is able to access to the grid successfully on the premise that the DC bus voltage is higher than minimum required limit. It will undoubtedly limit the applications of the grid-connected inverter. In order to reduce the application threshold of inverters, this paper has proposed a new design of the single-phase grid-connected LCL filter inverter. This design scheme can reduce the output voltage of the inverter bridge and hence reduce the dc bus voltage limit, where the LCL filter has a certain boost gain. So that the grid-connected inverter can get more applications in low-power occasions. At first, this paper analyzed the reason for the DC bus voltage's limit in the traditional single-phase grid-connected LCL filter inverter. And then based on a new idea of LCL filter design, a detailed single-phase grid-connected LCL inverter design was given using the voltage transform function of LCL filter. Finally, the simulation and experiment have verified the new design proposed in this paper.