基于全MOSFET和功率回路电感压降最低的新型混源功率变换器理论及其在分布式光伏并网发电中的应用基础

High frequency, high control bandwidth, high efficiency and low cost photovoltaic (PV) inverters and the related grid-tied control technique are very important for the application of the distributed PV power generator system. However, the characteristic of the silicon IGBT device limits the performace impovement of the switching frequency and the control loop bandwidth of grid-tied PV inverters. At the same time, it is very difficult to better the efficiency through dereasing the power losses of the inductors, since for a conventional voltage source or a current source inverter, the inductance in the power loop can hardly be reduced further.. In order to increase the switching frequency, the control loop bandwidth, and the efficiency for a grid-tied PV inverter, a novel MOSFET-based Hybrid Source Inverter (HSI) with the minimal inductor voltage drop in the power loop is proposed in this project. Firstly, the principle of HSI is investigated. Next, the special control of this type inverter will be analyzed, especially under the different working conditions and in the different control domains. And then, the power coupling between the HSI-based PV inverters and the distributed PV power generation system are studied, together with the reactive power control, and continuded with the control strategy to enhance the stability of the system. Finaly, the effectiveness of HSI on improving the efficiency and the stability of the distributed PV power generation system will be verified through simultaions and experiments.. It is certain that the proposed HSI theory and methology will advance the development of the high efficiency PV grid-tied inverter technique. It can also offer the strong research foundation for the appiclations of the power converters-based micro-grid, including the new methodology and hardwares.

低成本的高频、高带宽、高效光伏逆变器和稳定、可靠的并网技术对分布式光伏发电的推广应用至关重要。但是现有硅基IGBT器件本身特性限制了并网光伏逆变器开关频率以及控制带宽的进一步提高；同时，传统电压源和电流源逆变器本身难以通过减少功率回路电感压降来进一步降低导通损耗。因而，传统光伏并网逆变器的控制带宽和效率的提升都受到了一定限制。.为提高分布式并网并网逆变器的控制带宽以及效率，本项目提出了一种基于全MOSFET开关器件以及功率回路电感压降最低的新型混源逆变器方案。首先研究该类拓扑的形成演变规律；其次研究该类拓扑在不同工况以及不同坐标系下的特有控制规律；再次研究基于该类拓扑的分布式光伏发电系统的功率耦合、无功控制以及系统稳定问题；最后进行仿真和实验验证。.新型混源变换器的提出，能有效促进高效光伏并网逆变器技术的进一步发展，也能为基于电力电子变换器的微电网的稳定控制研究提供新的方法和直接硬件支持。

能源危机、环境变化使得发展可再生能源成为了迫切需求，其中作为能源变换核心设备的功率变流器成为广泛研究的热点，针对当前混源型变流器拓扑结构、建模控制以及与电网耦合机理缺乏深入研究的情况下，项目组对混源型变换器拓扑家族的衍变规律、物理建模、与电网接口耦合机理展开研究。本项目旨在探索和完善一种基于全MOSFET开关器件以及功率回路电感压降最低的新型混源型变流器的理论体系，以促进混源型变换器在可再生能源的广泛应用。. 项目通过对混源型变换器拓扑衍变规律研究，提出了基于耦合电感的混源型变换器拓扑，实现了混源型逆变器具有了向电网提供无功功率、单直流电源、直流侧电容自动均压的功能，同时根据对偶原理提出了混源型整流器拓扑结构。为解决混源型变换器模式切换的扰动问题，引入了无差拍控制，使混源型的控制从传统线性控制拓展到非线性控制，此外还实现了该系列拓扑的单级MPPT功能，提高了混源型变换器的实用性；为了进一步减小滤波器的电感量，提出了基于LLCL滤波器的混源型变流器器，实验证明，LLCL滤波器相对LCL滤波器可以减小38%的电感量，可以显著降低变流器的硬件成本，同时为了解决具有高阶滤波器的变换器控制难题，提出了一种混合单环阻尼控制方法，即降低了滤波器的功率损耗又提高了带宽，为高阶滤波器混源型变换器接入电网应用破除了理论障碍。. 该项目建立和完善了混源型变流器的理论体系，为混源型变换器的应用解决了理论难题，有力的支撑了混源型变换器的工业应用。