Abstract：This paper explores the limitations of neutral-point potential balancing problem for different loading conditions of three-level neutral-point-clamped inverters. It introduced a novel modulation approach for the complete control of the neutral-point potential. The new modulation approach, which based on the virtual space vector concept, guaranteed the balancing of the neutral-point potential for any load over the full range of converter output voltage and for all load power factors, and the only requirement being that the addition of the output three-phase currents equals zero. In order to avoid the abrupt change of output voltage vectors during the process of desired vector changing from one section to another, a novel space vector modulation algorithm is proposed where the same positive or negative small vectors are adopted as first active vector. Some experimental results are given to validate the method.
胡存刚, 王群京, 李国丽, 冯纪归, 姜卫东. 基于虚拟空间矢量的三电平NPC逆变器中点电压平衡控制方法[J]. 电工技术学报, 2009, 24(5): 100-107.
Hu Cungang, Wang Qunjing, Li Guoli, Feng Jigui, Jiang Weidong. A Neutral-Point Potential Balancing Algorithm for Three-Level Inverter Based on Virtual-Space-Vector. Transactions of China Electrotechnical Society, 2009, 24(5): 100-107.
[1] Nabae A, Takahashi I, Akagi H. A new neutral-point clamped PWM inverter[J]. IEEE Trans. Ind. Applicat., 1981, IA-17 (5): 518-523. [2] Nikola Celanovic, Dushan Boroyevich. A compre- hensive study of neutral-point voltage balancing problem in three-level neutral- point-clamped voltage source PWM inverters[J]. IEEE Transactions on Power Electronics, 2000, 15 (2): 242-248. [3] Oscar Alonso, Luis Marroyo, Pablo Sanchis, et al. Analysis of neutral-point voltage balancing problem in three-level neutral-point-clamped inverters with SVPWM modulation[C]. Industrial Electronics Society, IEEE 2002 28th Annual Conference, 2002, 2: 920-925. [4] 宋强, 刘文华, 严干贵. 基于零序电压注入的三电平NPC逆变器中点电压平衡控制方法[J]. 中国电机工程学报, 2004, 24 (5): 57-62. [5] 宋文祥, 陈国呈, 丁肖宇. 基于两类脉宽调制方式本质联系的三电平逆变器中点电压平衡控制的研究[J]. 电工技术学报, 2005, 20 (12): 53-58. [6] 宋文祥, 陈国呈, 武慧, 等. 一种具有中点电压平衡功能的三电平空间矢量调制方法及其实现[J]. 中国电机工程学报, 2006, 26 (12): 95-100. [7] Mouton H du Toit. Natural balancing of three-level neutral-point-clamped PWM inverters[J]. IEEE Transactions on Industrial Electronics, 2002, 49 (5): 1017-1025. [8] Josep Pou, Dushan Boroyevich, Rafael Pindado. New feed forward space-vector PWM method to obtain balanced AC output voltages in a three-level neutral-point-clamped converter[J]. IEEE Transac- tions on Industrial Electronics, 2002, 49 (5): 1026- 1034. [9] Sergio Busquets Monge, Josep Bordonau, Dushan Boroyevich. The nearest three virtual space vector PWM-a modulation for the comprehensive neutral- point balancing in the three-level NPC inverter[J]. IEEE Power Electronics Letters, 2004, 2 (1): 11-15. [10] 李永东, 肖曦, 高跃. 大容量多电平变换器——原理、控制、应用[M]. 北京：科学出版社, 2005. [11] Sergio Busquets Monge, Sergio Somavilla, Josep Bordonau, et al. Capacitor voltage balance for the neutral-point-clamped converter using the virtual space vector concept with optimized spectral performance[J]. IEEE Transactions on Power Electronics, 2007, 22 (4): 1128-1135.
2009, Vol. 24 
