Abstract：In this paper, working principle of three-level neutral point clamped (NPC) converter is analyzed. On this basis, combined with high power NPC control requirements and characteristics, a hybrid modulation strategy based on discontinuous space vector pulse width modulation (SVPWM) is proposed to reduce switching loss and keep neutral-point voltage balancing. The strategy consists of two parts. One is switching vector sequence to achieve neutral-point voltage balancing by detecting the direction of the three-phase instantaneous current at AC side and dc-link voltage difference, the other is applying no action principle of maximum or larger current phase to reduce switching loss. The switching between the two parts is controlled by hysteresis. Finally, the simulation and experimental results verify that the proposed strategy can effectively balance neutral-point potential and reduce switching loss. The algorithm is simple and has a certain practicality in engineering practice.
罗锐, 何英杰, 陈晖, 刘进军. 三电平变流器中点电位平衡及低开关损耗SVPWM策略[J]. 电工技术学报, 2018, 33(14): 3245-3254.
Luo Rui, He Yingjie, Chen Hui, Liu Jinjun. SVPWM Scheme for Three-Level Converters with Neutral-Point Potential Balancing and Switching Loss Reduction. Transactions of China Electrotechnical Society, 2018, 33(14): 3245-3254.
[1] Nabae A, Takahashi I, Akagi H.A new neutral point clamped PWM inverter[J]. IEEE Transactions on Industry Applications, 2008, 17(5): 518-523. [2] Yazdani A, Iravani R.A generalized state-space averaged model of the three-level NPC converter for systematic DC-voltage-balancer and current-controller design[J]. IEEE Transactions on Power Delivery, 2005, 20(2): 1105-1114. [3] Maheshwari R, Munk-Nielsen S, Busquets-Monge S.Design of neutral-point voltage controller of a three- level NPC inverter with small DC-link capacitors[J]. IEEE Transactions on Industrial Electronics, 2013, 60(5): 1861-1871. [4] 宋文祥, 陈国呈, 武慧, 等. 一种具有中点电位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. Song Wenxiang, Chen Guocheng, Wu Hui, et al.A novel SVPWM strategy and its implementation considering neutral-point potential balancing for three-level NPC inverter[J]. Proceedings of the CSEE, 2006, 26(12): 95-100. [5] 王志强, 邓臣臣, 谷鑫, 等. 基于中点钳位型三电平逆变器的改进型虚拟空间矢量调制策略[J]. 电工技术学报, 2017, 32(18): 230-238. Wang Zhiqiang, Deng Chenchen, Gu Xin, et al.The improved virtual space vector modulation strategy based on neutral-point-clamped three-level inverter[J]. Transactions of China Electrotechnical Society, 2017, 32(18): 230-238. [6] 王慧敏, 温坤鹏, 张云, 等. 基于精细分区控制的三电平逆变器中点电位平衡策略[J]. 电工技术学报, 2015, 30(19): 144-152. Wang Huimin, Wen Kunpeng, Zhang Yun, et al.Neutral point potential balance strategy for NPC three-level inverter based on meticulous partition control[J]. Transactions of China Electrotechnical Society, 2015, 30(19): 144-152. [7] 孙鹤旭, 荆锴, 董砚, 等. 基于120°坐标系的SVPWM算法研究[J]. 电工技术学报, 2016, 31(5): 52-59. Sun Hexu, Jing Kai, Dong Yan, et al.Research of SVPWM algorithm based on 120°coordinates system[J]. Transactions of China Electrotechnical Society, 2016, 31(5): 52-59. [8] Mcgrath B P, Holmes D G, Meynard T.Reduced PWM harmonic distortion for multilevel inverters operating over a wide modulation range[J]. IEEE Transactions on Power Electronics, 2017, 21(4): 941-949. [9] 周京华, 沈传文, 苏彦民. 多电平逆变器不连续空间矢量调制策略的研究[J]. 电力电子技术, 2005, 39(5): 15-17. Zhou Jinghua, Shen Chuanwen, Su Yanmin.Research on multilevel inverter discontinuous space vector modulation strategies[J]. Power Electronics, 2005, 39(5): 15-17. [10] 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. [11] 刘斌, 黄凯伦, 伍家驹, 等. 一种具有中点电位平衡可降低损耗的三电平空间矢量调制方法[J]. 电工技术学报, 2015, 30(4): 196-202. Liu Bin, Huang Kailun, Wu Jiaju, et al.A novel SVPWM method considering neutral-point potential balancing and reducing switching losses for three-level inverter[J]. Transactions of China Electrotechnical Society, 2015, 30(4): 196-202. [12] 姜卫东, 赵德勇, 汪磊, 等. 一种以降低逆变器开关损耗为目标并考虑中点电位平衡的适用于中点钳位式三电平逆变器的调制方法[J]. 中国电机工程学报, 2016, 36(5): 1376-1386. Jiang Weidong, Zhao Deyong, Wang Lei, et al.A modulation method with reduced switching losses and considering the neutral point voltage balance suitable for the neutral-point-clamped three-level inverter[J]. Proceedings of the CSEE, 2016, 36(5): 1376-1386. [13] 吴洪洋, 何湘宁. 多电平载波PWM法与SVPWM法之间的本质联系及其应用[J]. 中国电机工程学报, 2002, 22(5): 10-15. Wu Hongyang, He Xiangning.Relationship between multilevel carrier-based PWM and SVPWM and its applications[J]. Proceedings of the CSEE, 2002, 22(5): 10-15. [14] 孙青松, 吴学智, 唐芬. 考虑中点电位平衡的三电平逆变器断续脉宽调制策略研究[J]. 中国电机工程学报, 2017, 37(增刊1): 177-185. Sun Qingsong, Wu Xuezhi, Tang Fen.Study on discontinuous pulse width modulation strategy of three-level inverter considering neutral point potential balance[J]. Proceedings of the CSEE, 2017, 37(S1): 177-185. [15] 任康乐, 张兴, 王付胜, 等. 中压三电平并网逆变器断续脉宽调制策略及其输出滤波器优化设计[J]. 中国电机工程学报, 2015, 35(17): 4494-4504. Ren Kangle, Zhang Xing, Wang Fusheng, et al.Optimized design of discontinuous pulse-width modulation and output filter for medium-voltage three-level grid-connected inverter[J]. Proceedings of the CSEE, 2015, 35(17): 4494-4504. [16] Beig A R, Kanukollu S, Hosani K A, et al.Space-vector-based synchronized three-level dis- continuous PWM for medium-voltage high-power VSI[J]. IEEE Transactions on Industrial Electronics, 2014, 61(8): 3891-3901. [17] 林磊. 双三电平供电异步电机直接转矩控制系统研究[D]. 武汉: 华中科技大学, 2007. [18] 鄢志平, 何英杰, 李毅, 等. 三电平四桥臂SVG三电流滞环控制方法研究[J]. 中国电机工程学报, 2016, 36(20): 5575-5583. Yan Zhiping, He Yingjie, Li Yi, et al.Study on current hysteresis control method of three-level four bridge arm SVG[J]. Proceedings of the CSEE, 2016, 36(20): 5575-5583. [19] 戴鹏, 石祥龙, 朱晓莹, 等. 有源钳位三电平变频器改进SVPWM策略[J]. 电工技术学报, 2017, 32(14): 137-145. Dai Peng, Shi Xianglong, Zhu Xiaoying, et al.Improved SVPWM strategies for active neutral- point-clamped converters[J]. Transactions of China Electrotechnical Society, 2017, 32(14): 137-145. [20] 胡存刚, 马大俊, 王群京, 等. 三电平有源中点钳位逆变器损耗分布平衡控制策略[J]. 电工技术学报, 2017, 32(1): 129-138. Hu Cungang, Ma Dajun, Wang Qunjing, et al.Control strategy of loss distribution balancing for three-level active neutral-point-clamped inverter[J]. Transactions of China Electrotechnical Society, 2017, 32(1): 129-138.
2018, Vol. 33 
