单相非隔离光伏并网逆变器的研究

发布时间：2018-03-27 17:15

本文选题：非隔离　切入点：光伏并网　出处：《江苏大学》2017年硕士论文

【摘要】：太阳能最重要的利用形式之一就是光伏发电,然而其系统的经济性限制阻碍了光伏产业的发展,可探寻的突破口之一即开发高效的逆变器。非隔离光伏并网逆变器因不含变压器,具有效率高,体积小、重量轻和成本低等优势,但消除变压器的隔离作用后,电网侧与大地、寄生电容、光伏阵列之间形成了一条共模回路,导致了漏电流的产生,该漏电流对设备与人身安全存在极大的隐患。本文就高效率低漏电流的非隔离光伏并网逆变器展开研究工作。首先,概述了非隔离光伏系统中共模漏电流的产生机理,推导了其共模等效电路,总结了抑制共模漏电流的方法。针对全桥类拓扑,利用频域分析法归纳了寄生参数对共模漏电流的影响。再者,将该方法应用于传统全桥电路上,对共模特性进行分析,验证了消除漏电流理论分析的正确性。其次,分析归纳了六种典型拓扑的共模特性和优缺点,提出了一种新型七开关非隔离并网逆变拓扑,该拓扑抑制漏电流性能优越,运行安全可靠;同时,应用倍频SPWM调制策略,可降低器件的开关速度、减小并网电流纹波、降低馈入电网的谐波含量、减小并网滤波电感感值和损耗。在任意工作模态中开关管始终交错工作,有助于热应力均衡,简化了散热设计的难度。然后,针对并网电感续流期间非理想因素导致逆变器共模特性悬浮不稳定的现象。总结出了一套二极管箝位的通用定理,并将该定理应用于上述所有拓扑进行优化,经仿真验证,此方法可有效改善非理想因素下产生的共模电压的高频扰动,达到根除漏电流的目的。最后,设计完成了非隔离光伏并网逆变器通用实验样机,验证和对比了四种拓扑的共模特性和效率,其结果与仿真分析相吻合,进一步证明了理论分析的正确性。
[Abstract]:One of the most important forms of solar energy utilization is photovoltaic power generation. However, the economic limitation of solar energy system hinders the development of photovoltaic industry. One of the breakthroughs that can be explored is the development of efficient inverters. Unisolated photovoltaic grid-connected inverters have the advantages of high efficiency, small volume, light weight and low cost because they do not contain transformers, but after eliminating the isolation of transformers, the grid side and the earth are eliminated. Parasitic capacitors, photovoltaic arrays form a common mode loop, resulting in the generation of leakage current, The leakage current has great hidden danger to equipment and personal safety. In this paper, the research work of high efficiency and low leakage current non-isolated photovoltaic grid-connected inverter is carried out. Firstly, the mechanism of common mode leakage current in unisolated photovoltaic system is summarized. The common mode equivalent circuit is derived, and the method of suppressing the common mode leakage current is summarized. The influence of parasitic parameters on the common mode leakage current is summarized by frequency domain analysis for the full-bridge topology. Furthermore, the method is applied to the traditional full-bridge circuit. The common mode characteristics are analyzed, and the correctness of the theoretical analysis of eliminating leakage current is verified. Secondly, the common mode characteristics, advantages and disadvantages of six typical topologies are analyzed and summarized, and a new seven-switch non-isolated grid-connected inverter topology is proposed. The topology suppresses leakage current performance is superior, operation is safe and reliable, at the same time, the frequency doubling SPWM modulation strategy can reduce the switching speed of the device, reduce the ripple of the current connected to the grid, and reduce the harmonic content of the feed into the power network. The inductor inductance and loss of grid-connected filter are reduced. The switching tube always works interlaced in any mode of operation, which helps to balance the thermal stress and simplifies the difficulty of heat dissipation design. Then, In view of the unstable common-mode characteristic of inverter caused by non-ideal factors during the continuous current of grid-connected inductor, a set of general theorem of diode clamping is summarized and applied to optimize all the above topologies, which is verified by simulation. This method can effectively improve the high frequency disturbance of common-mode voltage generated by non-ideal factors and eliminate leakage current. Finally, a general experimental prototype of non-isolated photovoltaic grid-connected inverter is designed. The common mode characteristics and efficiency of the four topologies are verified and compared, and the results are in agreement with the simulation analysis, which further proves the correctness of the theoretical analysis.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464;TM615

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