多源直流微网中高增益串联混合型多端口DC-DC变换器的研究

Recently, in DC micro grid with new energy distributed generation and energy storage units, multiple-port DC-DC converter (MPC) has been paid more attention due to its low cost and high efficiency. However, the typology of MPC derived from traditional method is difficult to achieve high voltage conversion gain and meet the requirements from the photovoltaic and fuel cell power generation system. Moreover, energy from generator units to energy storage units usually require twice power conversion and the conversion efficiency is low. Based on the existing high step-up DC-DC converter, this project proposes to study its multiple-input law and methods to make up for the shortcomings of high voltage conversion gain in the current MPC construction. On this basis, research on the bidirectional series combination switch circuit for energy storage, which is used to control the direction of the energy storage unit to achieve its charge and discharge. By this way to reduce power conversion times between power generation unit and energy storage unit. The main research emphases of this project are the topology derivation method of the series hybrid high step-up MPC, the interaction mechanism between input ports and system control strategy, which researched successfully would help to supplement the existing MPC construction ideas and topologies. Research results from this project can also provide a new way to construct the system architecture for multiple-source DC Micro grid.

多端口DC/DC变换器(Multiple-Port Converter, MPC) 因成本、效率上的优势近年来在含新能源分布式发电和储能单元的直流微电网中受到了较多的关注。但目前构建方法下的拓扑电路难以实现高增益升压变换，不能满足光伏、燃料电池发电单元对高增益升压要求；且发电单元到储能单元通常需要两次电能变换，转换效率低。本项目提出从现有高增益DC/DC变换器入手，研究其多输入化规律及方法，弥补目前MPC构建思路下高增益升压变换方面的不足，在此基础上提出研究适合储能单元接入的双向串联型组合开关电路，利用开关切换改变储能单元串联在电路中的方向来实现充放电，解决目前方案中储能单元电能变换次数多的问题。本项目拟以高增益串联混合型MPC的拓扑构成、端口间相互作用机理及控制策略为研究重点，项目的研究成功可以对现有MPC构建思路和拓扑方案进行补充，研究成果也可为多源直流微网系统构架提供一种新的思路。

在分布式光伏、储能及电动汽车快速发展的背景下，研究适用于含分布式发电和储能单元的直流微电网所需多端口DC/DC变换器具有重要的实际意义。本项目的主要成果包括：首先开展了高增益DC/DC升压电路的多输入化研究，提出了数种具备双路输入的高增益DC/DC升压变换器拓扑电路，在此基础上，建立了相应的无损零电压关断辅助电路，实现了成本的降低和效率的提升。其次对适用于储能系统接入的双向变换拓扑优化组合进行研究，基于串联型双向变换拓扑优化组合研究思路，提出了数种可实现发电单元、储能单元及直流母线之间能量一次流转的变换器拓扑电路，并提出了相适应的控制思路和实现方法。最后针对所构建变换器开展了降阶线性化模型的研究，基于状态空间平均法，结合所提等效受控源的化简策略，建立了所提变换器的降阶线性化模型，并基于所构建降阶模型完成了控制器设计。同时将所提降阶模型构建思路进行了总结推广，形成了适用于“基于电压增益单元与传统Boost变换器相结合构建高增益DC/DC变换器”这一类拓扑的通用降阶模型构建方法。本项目研究成果对现有多端口DC/DC变换器构建思路和拓扑方案进行了有效补充，也为多源直流微电网系统构架提供一种新的思路。