基于低漏电流本征设计的双降压式并网逆变器拓扑理论与关键技术研究

The high efficiency and low leakage current design of grid-tied inverters are the key technology and challenge for the development of large-scale transformerless photovoltaic (PV) grid-connected generation systems applications. Dual-buck full-bridge grid-tied inverter is one of the most important technical ways to deal with this challenge. In this project, the dual-buck full-bridge grid-tied inverters will be investigated in terms of the systematical topology generation theory with low leakage current and application technologies, and the topology generation mechanism of dual-buck inverters will be revealed. This project is to research including ① a family of transformerless dual-buck full-bridge grid-tied inverters with low leakage current and their topology generation method; ② a system-level efficiency improvement method for two-stage transformerless full-bridge grid-tied inverters; ③ a cost-effective neutral point balancing control for multi-level dual-buck full-bridge grid-tied inverters; ④ a filter inductor optimized solution with multi-objective coordination including high efficiency, high reliability, and high density. The final target is to propose a novel solution of the dual-buck full-bridge grid-tied inverter with low leakage current, high efficiency, high reliability and high density characteristics. Based on the above achievements, the researches on the topology generation theory and high performance application technology in the field of “Dual-buck grid-tied inverters” will be promoted to a higher level, and also give a reference for transformerless PV grid-tied inverters.

并网逆变器的高效率和低漏电流设计是非隔离型光伏发电并网系统规模化应用进展中的关键问题与重大挑战，双降压式并网逆变器正是应对上述挑战的重要技术发展途径之一。本项目将主要研究基于低漏电流本征设计的双降压式并网逆变器拓扑衍生理论与应用关键技术，揭示双降压式并网逆变器的拓扑生成机理。拟研究并提出：①低漏电流双降压式并网逆变器及其拓扑衍生方法；②兼顾低漏电流和系统级效率优化的两级式双降压式全桥并网逆变器电路方案及调制策略；③多电平双降压式全桥并网逆变器低成本电容电压平衡策略；④综合考虑高效率、高可靠性和高功率密度的滤波电感优化方案。最终目标是提出并实现一整套高效率、高可靠性和高功率密度的低漏电流双降压式并网逆变器解决方案。本项目的研究成果将有力地提升我国在双降压式并网逆变器拓扑理论及高能效应用技术领域的研究水平，为非隔离型光伏并网逆变器的发展提供重要的理论支撑。

并网逆变器的高效率和低漏电流设计是非隔离型光伏并网发电系统规模化应用进展中的关键问题与重大挑战，双降压式并网逆变器正是应对上述挑战的重要技术发展途径之一。本项目研究了基于低漏电流本征设计的双降压式并网逆变器拓扑衍生理论与应用关键技术，揭示双降压式逆变器的拓扑生成机理。拟研究并提出：①低漏电流双降压式并网逆变器及其拓扑衍生方法；②兼顾低漏电流和系统级效率优化的两级式双降压式全桥并网逆变器电路方案及调制策略；③多电平双降压式全桥并网逆变器低成本电容电压平衡策略；④综合考虑高效率、高可靠性和高功率密度的滤波电感优化方案。最终目标是提出并实现一整套高效率、高可靠性和高功率密度的低漏电流双降压式并网逆变器解决方案。. 项目提出了高变换效率、高可靠性、高功率密度的双降压式全桥并网逆变器解决方案，难点是兼顾高效率、宽电压增益和低漏电流的单级和准单级拓扑的发现和调制策略。基于功率流分解与重构的基本思路，提出了一族单相双降压式低漏电流全桥并网逆变器拓扑及调制策略，相对于传统单相桥式低漏电流全桥并网逆变器拓扑，提高了变换效率；提出了单相双降压式和桥式准单级低漏电流并网逆变器拓扑及其调制策略，相对于传统两级式并网逆变器，减少了功率变换级数，提高了变换效率；提出了适用于光伏并网发电的三相准单级逆变器拓扑，低共模电压调制策略和电能质量治理方法；提出了五电平双降压式全桥并网逆变器及其中点电位平衡方法，无需分压电容采样电路即可实现电容平衡，降低了系统成本。研究了4种磁集成方案，双磁芯四绕组、共用磁芯完全解耦、共用磁芯直接耦合和流过相同电流耦合，对比了磁件数量、电感值和最大磁动势和等性能，双磁芯四绕组和流过相同电流耦合方法磁件体积较小，更适合高功率密度场合。. 项目的研究成果提升了我国在双降压式并网逆变器拓扑理论及高能效应用技术领域的研究水平，为非隔离型光伏并网逆变器的发展提供了理论支撑。