模块化LCC谐振变换器在光伏发电直流并网系统的应用

Application of modular LCC resonant converter in photovoltaic power generation DC grid-connected system

模块化LCC谐振变换器级联拓扑具有软开关、高功率密度、易于扩展、输出能力强等优势,在光伏并网领域有着极大的发展潜力,但也存在着输出电压不均衡的问题。多模块LCC变换器的不均压问题是由模块间参数偏差引起的,主要通过谐振参数偏差和共模干扰造成模块间不均压。针对容性滤波的两模块LCC变换器,建立了大信号模型计算各模块输出电压及不均压度,并搭建了两模块LCC变换器的样机平台,对所提出的含分布参数影响的两模块LCC模型进行了验证。所提模型可为变换器设计的容差分析提供依据,让模块化LCC变换器拓扑更稳定的应用于光伏并网系统。

The modular LCC resonant converter cascade topology has the advantages of soft switching, high power density, easy expansion, and strong output capability. It has great development potential in the field of photovoltaic grid-connected, but it also has the problem of unbalanced output voltage. The uneven voltage problem of the multi-module LCC converter is caused by the parameter deviation between the modules, which is mainly caused by the resonance parameter deviation and common mode interference. For the two-module LCC converter with capacitive filtering, a large-signal model was established to calculate the output voltage of each module, and a prototype platform of the two-module LCC converter was built to verify the proposed two-module LCC model. The proposed model can provide a basis for the tolerance analysis of the converter design, so that the modular LCC converter topology can be applied to photovoltaic grid-connected systems more stably.