一种新型的三电平逆变器中点电位平衡控制策略

Control Strategy of Neutral-point Potential Balancing in Three-level Inverter

提出一种抑制三电平逆变器中点电位波动的新型控制策略。在电压外环,针对中点电位一阶模型,采用二阶非线性扩张状态观测器实现中点电位扰动的实时估计;设计高性能非线性PI控制器实现母线电压的有效控制和中点电位波动的补偿。在10 kW三相光伏并网逆变器样机平台上进行相关实验,实验结果验证了该方法可以有效抑制中点电位波动,提高系统鲁棒性。

A novel control method applied in three-phase three-level inverter was proposed to realize neutral-pointpotential（NNP）balancing. In the voltage loop,aiming at the 1st-order model of NNP,the 2nd-order non-linearexpanded state observer（ESO）was adopted to estimate the disturbance of NNP in real-time,and a non-linear PI（NLPI）controller was designed to suppress the disturbance and control the bus voltage. A 10 kW prototype wasdesigned and developed,and the experiment results validate that not only the proposed method can suppress thefluctuation of NNP,but improve the robustness of the system.