共地型无漏电流单相非隔离光伏并网逆变器

Common-ground-type Single-phase Transformerless PV Grid-connected Inverters With No Leakage Currents

介绍一种新型共地型非隔离光伏并网逆变器,只需要5个功率开关、一个电容、和一个滤波器。采用一种简单的单极性正弦脉宽调制(sinusoidalpulsewidthmodulation,SPWM)技术对逆变器进行调制,以减小开关损耗、输出电流纹波,并降低滤波要求。新型逆变器拓扑的主要优点是:1)光伏电池的负端直接和电网中性点相连,完全消除漏电流,而传统的拓扑只能抑制漏电流;2)所用器件少,成本低;3)损耗低,效率高;4)具有无功功率传输的能力;5)相对于半桥型拓扑来说,不需要很高的直流输入。详细介绍新型拓扑的工作原理及模态、调制方式和控制策略,并将该新型拓扑与几种传统拓扑进行性能对比,所提出拓扑的漏电流抑制能力和效率均优于传统拓扑。最后设计1kVA的实验样机,给出实验结果,证明所提出拓扑在光伏并网系统中的有效性,为实际应用提供依据。

This paper presented a novel common-ground transformerless photovoltaic(PV)grid-connected inverter,which requires only five power switches,one capacitor and one filter.A simple unipolarity sinusoidal pulse width modulation technique was used to reduce the switching loss and output current ripple.The main advantages of proposed inverters are:1)The leakage current is completely eliminated(unlike traditional topologies,which can only suppress leakage current);2)The devices used are few and the cost is low;3)Low loss and high efficiency;4)The ability of realizing reactive power;5)There is no need for high DC input voltage compared to half-bridge-type topologies.The operating principle,modulation mode and control strategy were introduced in detail.The performance of the new topology was compared with that of several traditional topologies.The leakage current suppression ability and efficiency of the proposed topology were superior to those of the traditional topologies.Finally,simulation and experimental results of a 1 kVA prototype were given,which proves the validity of the proposed topology in PV grid-connected system.