基于软开关技术的DCM光伏微逆变器的研究与实现

发布时间：2018-02-01 16:39

本文关键词： 光伏微逆变器 DCM 软开关 MPPT 孤岛检测　出处：《中南大学》2014年硕士论文　论文类型：学位论文

【摘要】：摘要：太阳能是一种清洁、环保、分布广泛、储量无限的可再生能源。开发和利用太阳能并将其作为基础能源,是解决能源危机与环境危机的方法之一。太阳能分布式发电充分利用了太阳能分布广泛、储量无限的特点,是未来开发和利用太阳能的主要趋势。而光伏微逆变器发电系统具有太阳能利用率高、模块化、智能化等优点,是太阳能分布式发电的重要方式。本文以交错双反激式光伏微逆变器为研究对象,选取DCM(Discontinous Conduction Mode,非连续导通模式)为其工作模式。首先分析了交错双反激式微逆变器的基本工作原理以及使其工作在DCM模式下的条件,揭示了常规的反激式拓扑的反激式变压器励磁电感与反激式开关管输出电容谐振,导致在开关周期开始时励磁电感电流不能复位,进而导致输出波形畸变的问题。然后设计了有源钳位和软开关电路,提出一种分段式控制方法。新方法用励磁电感和钳位电容谐振时电流变化较慢的区间代替电流变化较快的区间,从而使励磁电感电流在开关周期开始时电流稳定在零附近,实现复位,解决了常规的反激式拓扑输出波形畸变的问题。同时,通过控制励磁电感电流与反激式开关管输出电容的谐振时间,实现反激式开关管的软开关。接着,基于所提出的分段式控制方法,提出一个200W的交错双反激式光伏微逆变器的设计方案。设计方案对微逆变器的反激式变压器进行详细的设计,对微逆变器的反激式开关管、辅助开关管、换向桥开关管、输出二极管、输入电容以及输出滤波器等主要器件进行选型。同时,设计方案提出了一种短路电流法和变步长扰动观察法相结合的MPPT控制方法和一种电压和频率相结合的孤岛检测算法。最后,通过仿真验证了本文所提出的分段式控制方法、MPPT控制方法以及孤岛检测算法的有效性,验证了本文所提出的微逆变器设计方案的可行性。并按照设计方案,制作出样机,进行测试实验。实验结果证明本文的设计方案合理、可行。
[Abstract]:Abstract: solar energy is a clean, environmental protection, widely distributed, unlimited reserves of renewable energy. Distributed solar power generation makes full use of the characteristics of wide distribution of solar energy and unlimited reserves. It is the main trend of developing and utilizing solar energy in the future, and the photovoltaic micro-inverter power generation system has the advantages of high utilization ratio, modularization, intelligence and so on, which is an important way of distributed solar power generation. In this paper, the DCM(Discontinous Conduction Mode is chosen as the research object of the interleaved dual-flyback photovoltaic micro-inverter. Discontinuous conduction mode) is its working mode. Firstly, the basic working principle of the interleaved dual-flyback micro-inverter and the condition of making it work in DCM mode are analyzed. It is revealed that the excitation inductance of the conventional flyback topology and the output capacitor resonance of the flyback switch can not be reset at the beginning of the switching cycle. Then the problem of output waveform distortion is caused. Then, the active clamping and soft switching circuits are designed, and a segmented control method is proposed. The new method uses the section with the excitation inductor and the clamped capacitance resonance to replace the section with the faster current change. Thus, the current of excitation inductor is stabilized near zero at the beginning of switching cycle, which realizes reset, and solves the problem of waveform distortion of conventional flyback topology output. At the same time. The soft switch of flyback switch is realized by controlling the resonant time of excitation inductance current and output capacitance of flyback switch. Then, based on the proposed segmented control method, a 200W interleaved dual-flyback photovoltaic micro-inverter design scheme is proposed. The design scheme of micro-inverter flyback transformer is designed in detail. The main devices such as flyback switch, auxiliary switch, commutation bridge switch, output diode, input capacitance and output filter are selected. A MPPT control method combining short circuit current method with variable step size perturbation observation method and an islanding detection algorithm combining voltage and frequency are proposed. Finally, the effectiveness of the segmented control method and the islanding detection algorithm are verified by simulation. The feasibility of the design scheme is verified. According to the design scheme, a prototype is made and tested. The experimental results show that the design scheme is reasonable and feasible.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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