基于改进型自抗扰控制器的NPC三电平逆变器中点平衡策略

Neutral point potential balance strategy for NPC three-level inverter based on improved active disturbance rejection control

针对中点钳位型三电平逆变器所固有的中点电位波动问题,建立直流侧中点电位的波动模型,提出一种基于分数阶自抗扰控制器(FOC-ADRC)的中点电压平衡策略。避免了传统ADRC的非线性误差反馈率(NLSEF)需要凭经验试凑三个没有明确物理意义的参数难题,便于应用到三电平逆变器的中点电位进行电压实时补偿。原理样机实验表明该方法具有较强的中点电压平衡性能,可以快速估测并抑制中点电压波动,同时减小输出电压电流的谐波。

Aiming at the neutral point potential fluctuation problem inherent in the neutral point clamp type three-level inverter,the fluctuation model of the DC side neutral point potential is established,and a neutral point poten-tial balance strategy based on the fractional-order active disturbance rejection control(FOC-ADRC)is proposed.It avoids the difficult problem that is necessary to set physically meaningless parameters by experience in the Nonlin-ear State Error Feedback Control Law(NLSEF)of ADRC,making it easy to apply in the neutral point potential of the three-level inverter for real-time voltage compensation.The prototype experiment shows that the method has strong neutral point voltage balance performance,can quickly estimate and suppress the neutral point voltage fluctu-ation,and reduce the harmonic of the output voltage and current.