Abstract：The neutral point voltage balancing control of three-level neutral-point-clamped inverter is still a hot researching point, the solutions of which can be classified into two categories: adding accessory hardware circuit and improving modulating means. In respect of size, loss and stability of the system, the latter is more preferred. SVM has a good performance on three-level NPC inverter voltage balancing while the complexity increases largely as a result of the increasing levels, by contrast SPWM injected zero-sequence voltage is much simpler. This paper makes a study on the control mechanism of SPWM injected zero-sequence voltage. It is theoretically proved that only 6n times zero-sequence voltage injected into reference voltages could draw a dc part which can be adjusted by amplitude and initial phase angular of zero-sequence in the neutral point over a fundamental period to do voltage balancing control, neither do the 6n-3 times zero-sequence voltage. Numerical simulations are identical to the conclusion.
王新宇, 何英杰, 刘进军. 注入零序分量SPWM调制三电平逆变器直流侧中点电压平衡控制机理[J]. 电工技术学报, 2011, 26(5): 70-77.
Wang Xinyu, He Yingjie, Liu Jinjun. Neutral-Point Voltage Balancing Principle of NPC Inverter Modulated by SPWM Injected Zero-Sequence Voltage. Transactions of China Electrotechnical Society, 2011, 26(5): 70-77.
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2011, Vol. 26 
