新型单相光伏并网逆变器共模电流抑制研究

Research on common mode current suppression of a novel single-phase grid-connected photovoltaic inverter

针对现有非隔离单相光伏并网逆变器拓扑共模电流大、效率低等问题,提出一种新型非隔离单相光伏并网逆变器拓扑,该拓扑在单相全桥逆变器的基础上增加2个续流二极管,并将交流侧滤波电感移至逆变器下桥臂,使得开关周期内共模电压保持恒定,有效抑制了共模电流;同时高频开关管使用MOSFET,工频开关管使用IGBT,且避免引入额外的开关管,系统整体损耗降低。通过对3 kW系统的仿真和实验,验证了新型拓扑抑制共模电流的效果。

Aiming at the problems of large common mode current and low efficiency of existing transformerless single-phase grid-connected photovoltaic inverters,a novel transformerless single-phase grid-connected photovoltaic inverter topology is proposed in this paper.In this novel topology,two freewheeling diodes are added to the single-phase full-bridge inverter,and the AC side filter inductors are moved to the lower bridge arms of the inverter,so that the common mode voltage remains unchanged during the switching period,which effectively suppress the common mode current.Meanwhile,MOSFET is used in high frequency switching tube,IGBT is used in power frequency switching tube,and additional switching tubes are avoided.Therefore,the overall loss of the system is reduced.Finally,the effect of the novel topology suppression common mode current is verified by simulation and experiment of 3 kW system.