Abstract The essential problem of the neutral point voltage converters is that how to keep voltage balance of the dc-link capacitors. Zero sequence voltage can be injected to control the neutral point voltage balance of the three-level converter, but low frequency fluctuations cannot be eliminated when the modulation index is high or power factor is low. The double signal PWM method can eliminate the neutral point fluctuation in the whole range, but will increase the switching frequency and deteriorate the output waveforms of the inverter. In this paper, a hybrid modulation scheme is adopted to achieve the goal of eliminating the low frequency fluctuation and reducing the switching frequency. The above advantages of the hybrid modulation scheme are verified by simulation and experimental results.
Yu Shiyao,Wang Chenchen,Xin Hongliang等. Hybrid PWM Strategy for Neutral Point Voltage Fluctuation Suppression of Three Level Neutral Point Clamped Converter[J]. Transactions of China Electrotechnical Society, 2016, 31(增刊): 146-154.
[1] Nabae A, Takahashi I, Akagi H. A new neutraloint- clamped PWM inverter[J]. IEEE Transactions on Industry Application, 1981, 17(5): 518-523. [2] 宋文祥, 陈国呈, 陈陈. 基于矢量合成的三电平空间电压矢量调制方法[J]. 电工技术学报, 2007, 22(10): 91-96. Song Wenxiang, Chen Guocheng, Chen Chen. A space vector modulation method of three-level NPC inverter based on synthesizing vectors concept[J]. Transactions of China Electrotechinal Society, 2007, 22(10): 91-96. [3] Bhat A, Langer N. Capacitor voltage balancing of three-phase neutral-point-clamped rectifier using modified reference vector[J]. IEEE Transactions on Power Electronics, 2014, 29(2): 561-568. [4] Choi U M, Lee J S, Lee K B. New modulation strategy to balance the neutral-point voltage for three-level neutral-clamped inverter systems[J]. IEEE Transactions on Energy Conversion, 2014, 29(1): 91-100. [5] 姜卫东, 王群京, 陈权. 二极管钳位型多电平逆变器全范围电容电压平衡的PWM调制方法[J]. 中国电机工程学报, 2009, 29(15): 28-35. Jiang Weidong, Wang Qunjing, Chen Quan. PWM algorithm for diode clamped multi-level voltage source inverter with capacitor voltage balance under full condition[J]. Proceedings of the CSEE, 2009, 29(15): 28-35. [6] 宋强, 刘文华, 严干贵, 等. 基于零序电压注入的三电平NPC逆变器中点电位平衡控制方法[J]. 中国电机工程学报, 2004, 24(5): 57-62. Song Qiang, Liu Wenhua, Yan Gangui, et al. A neutral-point potential balancing algorithm for three- level NPC inverters by using analytically injected zero-sequence voltage[J]. Proceedings of the CSEE, 2004, 24(5): 57-62. [7] 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[J]. Transac- tions of China Electrotechnical Society, 2011, 26(5): 70-77. [8] 冯晓云, 宋文胜. 一种基于零序电压分量注入的单相三电平载波PWM算法[J]. 电工技术学报, 2013, 28(4): 140-148. Feng Xiaoyun, Song Wensheng. A single phase three- level carrier-based PWM scheme with zero-sequence voltage injection[J]. Transactions of China Elec- trotechnical Society, 2013, 28(4): 140-148. [9] Wang Chenchen, Li Yongdong. Analysis and calcula- tion of zero-sequence voltage considering neutral-point potential balancing in three-level NPC converters[J]. IEEE Transactions on Industry Electronics, 2010, 57(7): 2262-2271. [10] Sergio B, Josep B, Dushan B. 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, 12(l): 11-15. [11] Pou J, Zaragoza J, Rodriguez P. Fast-processing modulation strategy for the neutral-point clamped converter with total elimination of low-frequency voltage oscillations in the neutral point[J]. IEEE Transactions on Industry Electronics, 2007, 54(4): 2288-2294. [12] 王琛琛, 张灿, 游小杰. 基于双调制波的中点电压平衡算法[J]. 电工技术学报, 2012, 27(3): 166-170. Wang Chenchen, Zhang Can, You Xiaojie. A neutral- point voltage balancing algorithm based on double signal PWM method[J]. Transactions of China Elec- trotechnical Society, 2012, 27(3): 166-170. [13] Rangarajan M, Rajendra N, Thomas A. A carrier- based PWM scheme for neutral-point voltage balancing in three-level inverters[J]. IEEE Transactions on Industry Applications, 2005, 41(6): 1734-1743. [14] Jiang Weidong, Du Shaowu, Chang Liuchen. Hybrid PWM strategy of SVPWM and VSVPWM for NPC three-level voltage-source inverter[J]. IEEE Transac- tions on Power Electronics, 2010, 25(10): 2607-2619. [15] Xia Changliang, Shao Hongjun, Zhang Yun. Adjustable proportional hybrid SVPWM strategy for neutral-point clamped three-level inverters[J]. IEEE Transactions on Industrial Electronics, 2013, 60(10): 4234-4242. [16] 王琛琛. 多电平变换器拓扑、PWM算法及中点电压控制的研究[D]. 北京: 清华大学电机系, 2008.
2016, Vol. 31 
