非隔离三电平电压型并网逆变器共模电流抑制策略

针对无变压器非隔离型三电平并网逆变器共模电流问题，详细分析了影响共模电流的主要因素。根据非隔离型三电平并网逆变器的共模等效结构模型，采用能消除共模电压的SPWM调制策略和改进LC滤波器方法，抑制共模电流。LC滤波器滤除寄生电容电压高频分量，改变了直流侧中点电位的平衡机理。改进的注入零序电压分量方法使中点电位得到有效控制。仿真验证了共模电流抑制策略的有效性。

Common-Mode Current Suppression Strategy of Non-Isolated Three-Level Voltage Grid-Connected Inverter

For common-mode current of non-isolated three-level voltage grid-connected inverter, the main factors affecting the common-mode current were analyzed in detail. According to common-mode equivalent structural model of the non-isolated three-level grid-connected inverter, SPWM modulation strategy which can eliminate the common-mode voltage and improve LC filter method was used to attenuate the common-mode current, the improved LC filter can to filter out the parasitic capacitance of the high-frequency components, at the same time, changing the balance mechanism of DC side midpoint potential. The improved injecting zero-sequence voltage component method makes the midpoint potential to be controlled effectively. The simulation verifies the effectiveness of the strategy on the suppression of common-mode current.