三电平逆变器中点振荡和漏电流抑制方法

Neutral Oscillation and Leakage Current Suppression Method for Three-level Inverter

针对T型三电平光伏并网逆变器,提出一种SPWM调制和电压控制器,该调制策略不仅能够抑制中点电位振荡,而且能够实现中点电位偏移控制。非隔离光伏并网逆变器存在漏电流问题,通过分析发现漏电流和共模电压正相关,因此重新排列开关次序,舍弃较大的共模电压,从而实现了漏电流的抑制。最后,通过仿真验证所提调制和控制的正确性。

For T tri-level photovoltaic（PV）grid inverter,a SPWM modulation and voltage controller was proposed,the modulation strategy not only controlled the midpoint potential oscillation suppression,but also controlled the neutral voltage offset control. Unfenced PV grid inverter have the problems of leakage current,the leakage current and common mode voltage were found to be related by analysis,so the switch order was rearranged,parted with larger common-mode voltage,so as to realize the inhibition of leakage current. Finally,the simulation verifies the correctness of the proposed modulation and control.