交流侧辅助升压宽输入逆变器原理研究

The output external characteristic of new energy power generation system is soft, and severely influenced by the outside environment, thus requires the grid-tied inverters have wide input voltage adaptive capacity. High efficiency and high power density wide input rang grid-tied inverter have been the pursuit of the goal. In this study, a new idea of ac side auxiliary boosting type inverter is proposed, getting insight into the work mechanism of ac side auxiliary boosting, finding the general rule to design the wide input range inverter topology, deriving topological implementation scheme with high gain and low leakage current characteristics; researching the power density optimization method with the aim of minimum inductor design and low switching loss modulation strategy with the "minimum booster" characteristics; seeking the grid current control strategy with quasi-LCL filter to realize stable and efficient dual mode switching; summarizing the conclusions through comparative analysis of the ac side auxiliary boosting and dc side boosting schemes in efficiency, power density, reliability, and so on. Compared to inverter with step up transformer, the ac side auxiliary boosting inverter can adjust the voltage ratio continuously with improved efficiency and power density; compared to dc side boosting inverter, it can reduce the number of passive elements with high reliability and easy integration, thus improve the power density significantly. The research will be helpful to provide a new train of thought and view for wide input range inverter realization.

新能源发电系统输出外特性较软，受外界环境影响大，要求并网逆变器具有宽输入电压适应能力，高效率和高功率密度的宽输入并网逆变器是研究人员一直所追求的目标。本课题提出并研究交流侧辅助升压型逆变器新思路，获得对交流侧辅助升压工作机理的理论认识，并归纳得到宽输入逆变器拓扑设计的一般性规律，推导具有高增益和低漏电流特征的拓扑实现方案；研究以电感最小化设计为目标的功率密度优化方法和具有"最小升压"特性的低开关损耗调制策略；寻求能实现稳定高效双模式切换的类LCL滤波并网电流控制策略；总结交流侧辅助升压与直流侧升压方案在效率、功率密度、可靠性等方面的综合性能对比分析结论。交流侧辅助升压逆变器相比工频升压型逆变器，可实现变比的连续可调，提高了效率和功率密度；相比直流侧升压逆变器，减少了无源元件的数量，可靠性高、更易实现集成化，显著提高了功率密度。课题的研究将有助于为宽输入逆变器提供一种全新的实现思路和视角。

分布式发电作为传统发电模式的有益补充，具有环境污染小，传输效率高的优势。太阳能和燃料电池是分布式发电的重要能量来源，但其输出易受外界环境的影响，外特性软，因此功率调整单元逆变器应具有宽输入电压的能力。本课题提出并研究交流侧辅助升压型逆变器新思路，获得对交流侧辅助升压工作机理的理论认识，并归纳得到宽输入逆变器拓扑设计的一般性规律，推导具有高增益和低漏电流特征的拓扑实现方案；研究以电感最小化设计为目标的功率密度优化方法和具有“最小升压”特性的低开关损耗调制策略；寻求能实现稳定高效双模式切换的类LCL滤波并网电流控制策略；总结交流侧辅助升压与直流侧升压方案在效率、功率密度、可靠性等方面的综合性能对比分析结论。交流侧辅助升压逆变器相比工频升压型逆变器，可实现变比的连续可调，提高了效率和功率密度；相比直流侧升压逆变器，减少了无源元件的数量，可靠性高、更易实现集成化，显著提高了功率密度。课题的研究将有助于为宽输入逆变器提供一种全新的实现思路和视角。