基于dsPIC的PV逆变器的一种改进结构及其实现

针对目前PV光伏并网发电系统的核心逆变器的现状、结构和控制方法进行了详细的分析，从电网、PV系统及用户的需求出发，指出传统的单级全桥逆变器普遍具有不能处理较宽的输入PV电压，且需要重型工频升压变压器等缺点。在此基础上，本文创新设计并实现了一种基于单级全桥逆变器的并联耦合改进结构。实测证明这种并联耦合反激结构可以有效地减小通过大容量输入电解电容的纹波电流的RMS，从而延长电容的寿命；还可减小输出电流的纹波，从而降低输出电流的THD（谐波失真）；还可适应较宽的输入电压，减小交流纹波，减小磁芯，同时可以提供较高的额定输出电流等优点。

An improved structure and implementation of PV inverter based on dsPIC

The status,structure and control methods of the core(inverter) in the current grid-connected photovoltaic(PV) generation system are analyzed.Proceeding from the grid,PV system and the user′s needs,this article points out that the traditional single-stage full-bridge inverters in common can not handle the wide input PV voltage and requires heavy-duty step-up transformer.An improved parallel-coupled structure based on the structure of single-stage full-bridge inverter was innovatively designed and implemented to overcome the above mentioned shortcomings.The tested result proves that the parallel-coupled flyback structure can effectively reduce the RMS of ripple current which goes through the high-capacity electrolytic capacitor,the output current ripple,the AC ripple,the magnetic core,the output current THD(harmonic distortion),adapt to a wide input voltage,and provide a higher rated output current.