一种NPC三电平逆变器过调制中点电位控制方法

三电平逆变器工作在过调制区域时,中矢量的作用促进了中点电位的波动,然而常规中点电位控制方法不能从根本上解决这个现象。针对该问题提出了一种可以适用于过调制区域的虚拟矢量调制方法,该方法通过虚拟中矢量代替原中矢量参与参考矢量的合成,能够在调制的过程中解决中矢量带来的中点电位波动问题。该方法能够很好的控制了中点电位的波动情况。仿真的实验结果表明了方法的可行性和有效性。

A Neutral-point Voltage Balancing Over-Modulation Method of Three-Level NPC Inverter

Abstract: When three-level neutral point clamped (NPC) inverters work at over-modulation phase, the middle vector leads to fluctuation of the neutral-point voltage, which cannot be well controlled by common neutral-point voltage balance control techniques. Aimed to solving this issue, a new virtual vector method is proposed to be applied in over-modulation. The characteristic of this method is to use the virtual middle vector instead of the combination of the original vector and the reference vector. Simulation results demonstrate that the new method can effectively mitigate fluctuation of neutral-point voltages in the process of modulation. So the method is feasible to be used in the future.