三电平逆变器中点电位平衡控制算法研究

Study on the Algorithm of Midpoint Potential Balance Control of Three-level Inverter

针对NPC型三电平逆变器,以主电路的拓扑结构为基础出发,分析SVPWM的调制原理,计算出每个空间电压矢量的作用时间。搭建主电路直流母线电容的数学模型,得出致使中位点电压不平衡的原因,进而提出一种基于时间分配因子的方法,实现对中位点电压大幅度波动的抑制。最后用MATLAB/Simulink平台下搭建仿真模型,对提出方法能否抑制中点电位波动进行验证。测试结果证实该方法的可行性,能有效抑制中点电压的波动。

Based on the topology of the main circuit and the modulation principle of SVPWM,the action time of each vector is calculated.Then the mathematical model of dc busbar capacitance of the main circuit is established,the cause of the unbalance of midpoint potential is obtained,and a method based on time distribution factor is put forward to realize the control of midpoint voltage.Finally,a simulation model is built on the MATLAB/Simulink platform to verify whether the proposed method can suppress the midpoint potential fluctuation.The experimental results show that this method is feasible and can effectively suppress the voltage fluctuation at the midpoint.