Transformerless Inverter With Virtual DC Bus Concept for Cost-Effective Grid-Connected PV Power Systems
Transformerless Inverter With Virtual DC Bus Concept for Cost-Effective Grid-Connected PV Power Systems
复制标题
具有虚拟直流母线概念的无变压器逆变器，适用于经济高效的并网光伏发电系统
DOI：
10.1109/tpel.2012.2203612
复制
发表时间：
2013-02-01
影响因子：
6.7
通讯作者：
He, Xiangning
中科院分区：
文献类型：
--
作者：
Gu, Yunjie;Li, Wuhua;He, Xiangning
为了消除无变压器光伏系统中的共模泄漏电流，提出了虚拟直流母线的概念。通过将电网中性线直接连接到直流母线的负极，绕过了光伏电池板和地之间的杂散电容。因此，可以完全抑制共模接地泄漏电流。同时，创建虚拟直流母线，为负交流电网电流的产生提供负电压电平。因此，所需的直流母线电压仍与全桥逆变器相同。在此基础上，提出了一种基于开关电容技术实现虚拟直流母线的新型无变压器逆变器拓扑结构。它只由五个电源开关、两个电容器和一个滤波电感组成。因此，可以降低电力电子设备的成本。这种先进的拓扑可以用单极正弦脉宽调制(SPWM)和双频SPWM调制来减小输出电流纹波。因此，可以使用更小的滤波电感来减小尺寸和磁损耗。详细分析了所提出的无变压器拓扑的优点，并用500W的样机进行了验证。
In order to eliminate the common-mode (CM) leakage current in the transformerless photovoltaic (PV) systems, the concept of the virtual dc bus is proposed in this paper. By connecting the grid neutral line directly to the negative pole of the dc bus, the stray capacitance between the PV panels and the ground is bypassed. As a result, the CM ground leakage current can be suppressed completely. Meanwhile, the virtual dc bus is created to provide the negative voltage level for the negative ac grid current generation. Consequently, the required dc bus voltage is still the same as that of the full-bridge inverter. Based on this concept, a novel transformerless inverter topology is derived, in which the virtual dc bus is realized with the switched capacitor technology. It consists of only five power switches, two capacitors, and a single filter inductor. Therefore, the power electronics cost can be curtailed. This advanced topology can be modulated with the unipolar sinusoidal pulse width modulation (SPWM) and the double frequency SPWM to reduce the output current ripple. As a result, a smaller filter inductor can be used to reduce the size and magnetic losses. The advantageous circuit performances of the proposed transformerless topology are analyzed in detail, with the results verified by a 500-W prototype.