基于PI+重复控制的三电平逆变器研究

Research on Three-level Inverter Based on PI+Repetitive Control

三电平中点箝位型(NPC)逆变器带不平衡负载时三相输出电压不平衡,严重影响负载的供电质量。传统双闭环比例积分(PI)控制虽然具有良好的动态响应,但却无法抑制这种不平衡,而重复控制可以有效抑制输出电压不平衡,但动态响应速率慢。这里通过分析逆变器带不平衡负载时三相输出电压不平衡机理,提出一种双闭环PI+重复控制的复合控制策略,并对双闭环PI控制器和重复控制器进行了设计。仿真和实验结果验证了该策略具有较好的动态性能且有效抑制由不平衡负载引起的输出电压不平衡。

The three-phase output voltage of three-level neutral point clamped(NPC)inverter with unbalanced load is unbalanced,which seriously affects the power supply quality of the load.Although the traditional double closed-loop proportional integral(PI)control has good dynamic response,it can not suppress this unbalance,while repetitive control can effectively suppress the output voltage unbalance,but the dynamic response rate is slow.By analyzing the mechanism of three-phase output voltage unbalance under unbalanced load,a compound control strategy of double closed-loop PI+repetitive control is proposed,and the double closed-loop PI controller and repetitive controller are designed.Simulation and experimental results show that the proposed method can effectively suppress the output voltage imbalance caused by unbalanced load.