【作者】 李敏；

【导师】 陈敏； 徐德鸿；

【作者基本信息】 浙江大学 ， 电力电子与电力传动， 2011， 硕士

【摘要】 能源问题和环境问题已经成为制约人类社会可持续发展的两大重要问题,因此光伏、风能和燃料电池等绿色新能源发电系统受到越来越广泛的重视。在这些可再生能源中,光伏发电有着它特有的优势。光伏逆变器作为光伏发电系统中能量传输的重要装置,其转换效率是衡量发电系统性能的重要指标之一。对于逆变器系统,其效率和输出的并网电流THD是有相关性的,因此本文首先通过电路等效,将光伏逆变器的主电路变换成为等效电路,给出了一种计算逆变器并网电流的方法,比较了理想情况下三种调制方式的并网电流THD。分析了实际系统中插入的死区对逆变器输出电压基波和谐波的影响,比较了几种调制策略在存在死区时对并网电流的THD的影响,选出了THD最优的调制序列,为提高效率奠定了基础。然后通过对并网逆变器的三大主要损耗来源,功率器件、滤波电感和变压器的损耗分别建立了损耗模型,对逆变器整体效率进行系统的比较分析。在计算滤波电感磁损时,针对其激励电流非正弦的特点,使用了Ansoft Maxwell这一有限元分析软件进行计算。通过对不同的SVM调制序列的逆变器各部分损耗进行计算和比较,得出了总体效率最优的调制序列。最后设计了实验平台的主电路参数,并在样机上的实验结果对部分理论分析进行了验证。更多还原

【Abstract】 Energy and environment issues are two important issues which become a constraint for sustainable development of human society, so photovoltaic, wind power, fuel cells and other renewable energy generation systems are more and more widely appreciated. Among these renewable energy sources, PV has its unique advantages, PV inverter used as a major energy transmission device in PV system, the conversion efficiency is which is a measure of an important indicator of power generation systems.The conversion efficiency of a inverter system and the total harmonic distortion (THD) of its output current injected to the grid are interrelated, Firstly this paper turns the PV inverter main circuit to the circuit that can be calculated through equivalence. Then THDs of grid current in ideal case using three different modulations are compared based on the method proposed to figure out grid-side current of the inverter. After the impact of dead time zone on fundamental and harmonic output voltage of inverter analyzed, modulation strategies were compared in the presence of the grid current THD when employing different dead time zone to obtain an optimal modulation scheme, which is the basis for efficiency.Then loss models of power devices, filter inductors and transformer which are main loss sources of gird-connected inverter were established. The overall efficiency of the inverter was made a systematic comparison. Due to the non-sinusoidal excitation current in the filter inductor, the FEA software Ansoft Maxwell was employed to predict iron loss in the filter. The modulation scheme which can archive best overall efficiency was pick out through the caparison of loss in different parts using three different SVM schemes.Finally, the main circuit of the experimental platform was designed, and the experimental results carried out on a prototype provide verification for some of the theoretical analysis.更多还原