三电平光伏逆变器漏电流和中点平衡研究

Reseach on Leakage Current and Midpoint Balance of Three-level Photovoltaic Inverter

光伏并网逆变器对漏电流有严格的限制,故DC/DC电容中点和三电平逆变器电容中点相连,和传统方法相比,可较好地抑制漏电流,而且能够实现中点平衡控制。后级逆变器采用一种无差拍和空间矢量调制策略,实现并网电流控制。提出方法的优势为:能够有效抑制漏电流;当调制度较大时,能够很好地并网;该控制方法和PI方法相比,具有较快的动态响应。通过仿真和实验验证所提算法的正确性。

Photovoltaic grid connected inverter has a strict limitation on leakage current.Therefore,DC/DC capacitor midpoint and three level inverter capacitor midpoint were connected.Compared with traditional methods,it could better suppress leakage current.And this method could realize the middle point balance control.The post stage inverter was adopted a strategy of no beat and space vector modulation to realize the grid connected current control.The advantages of this method were as follows:it could effectively suppress leakage current;when the modulation system was large,it could be connected well;the control method had faster dynamic response compared with the PI method.The correctness of the proposed algorithm is verified by simulation and experiment.