新型光伏并网逆变器及其漏电流分析

Novel Photovoltaic Grid-connected Inverter and Leakage Current Analysis

共模漏电流是非隔离型三相光伏并网系统亟待解决的问题。针对非隔离型三相三电平光伏并网逆变器(ESI)存在的共模漏电流抑制不足、并网电流谐波大等问题,提出一种三相三电平逆变器结构(NESI)及其调制策略,通过对中点钳位的三极管合理开断,保持共模电压的恒定。MATLAB仿真结果表明,该NESI逆变器能有效抑制共模漏电流。

Common mode leakage current is an urgent problem to be solved in a non-isolated three-phase photovoltaic grid-connected system.Aiming at the problems of insufficient common-mode leakage current suppression and large grid-connected current harmonics of the non-isolated three-phase three-level photovoltaic grid-connected inverter(ESI),a three-phase three-level inverter structure(nESI)and its modulation strategy were proposed.The transistors clamped at the midpoint were disconnected reasonably to keep the common mode voltage constant.MATLAB simulation results showed that the NESI inverter could effectively suppress common-mode leakage current.