Analysis of the Neutral Point Potential Variation of Neutral-Point-Clamped Voltage Source PWM Inverters
Analysis of the Neutral Point Potential Variation of Neutral-Point-Clamped Voltage Source PWM Inverters
复制标题
中点钳位电压源PWM逆变器中点电位变化分析
DOI：
10.1541/ieejias.113.41
复制
发表时间：
1993
影响因子：
--
通讯作者：
H. Akagi
中科院分区：
文献类型：
--
作者：
S. Ogasawara;T. Sawada;H. Akagi
中点箝位电压源逆变器（NPC-VSI）是一种双串联逆变器，它不需要输出变压器和电抗器，就能输出5电平阶跃电压，从而减少谐波电流。NPC-VSI适用于高压应用，因为NPC-VSI中使用的开关器件所需的额定电压仅为直流链路电压的1/2。然而，当中性点电流流入或流出直流母线时，中性点电位发生变化，在最坏的情况下，直流母线电压可能作用在开关器件上，本文从理论上对中性点电位的变化进行了讨论，并提出了抑制中性点电位变化的方法。这是基于零序电压的控制，零序电压是DC链路的中心与负载的中性点之间的电压差。对感应电机矢量控制系统进行了分析。因此，它表明，该方法可以完全抑制的电位的变化，除了一个特殊的操作条件。此外，还阐明了直流电容器的电位变化与电容量的关系，为直流电容器的设计提供了依据。
A neutral-point-clamped voltage source inverter (NPC-VSI), which is one of double series connected inverters, is able to output 5 level step-shaped line to line voltage without output transformers or reactors, thus reducing harmonic currents. The NPC-VSI is suitable to high voltage applications, because the required voltage rating of the switching devices used in the NPC-VSI is only 1/2 of the DC link voltage. However, the DC link voltage may be applied to the switching devices in the worst case if the potential of neutral point the DC link varies because of the flow-in or flow-out of the neutral point current.In this paper, the authors discuss the variation of the neutral point potential theoretically, and propose a suppression method of the variation. This is based on the control of a zero-sequence voltage that is a voltage difference between the center of the DC link and the neutral point of a load. The analysis is done for the vector control drive system of an induction machine without or with the proposed suppression method. Consequently, it is shown that the variation of the potential can be completely suppressed by the method except for a special operating condition. Moreover, the relation between the potential variation and the capacity of the DC capacitor is clarified to lead to the desing of the DC capacitor.