Research on Leakage Current Suppression of Novel Three-Phase Three-Level Non-Isolated PV Inverter
Guo Xiaoqiang, Zhu Tieying
Key Laboratory of Power Electronics for Energy Conservation and Drive Control of Hebei Province School of Electrical Engineering Yanshan University Qinhuangdao 066004 China
Abstract：A novel three-phase three-level non-isolated PV inverter is proposed in this paper based on the neutral-point-clamped (NPC) inverter. The characteristics of working states and leakage current were studied. Different from the NPC inverter, the topology of proposed inverter is so brief and it only consists of twelve switches and two DC capacitors without extra devices, such as six clamped diodes for the NPC. In order to suppress the leakage current, the relationship between the switch states and the common-mode voltage was analyzed and a novel Single-Carrier modulation was proposed based on the traditional modulation for two-level inverters. Finally, in order to verify the effectiveness of the proposed circuit and modulation strategy, the simulations and the experiments connected to the grid, inductance experiments were conducted. The results of the simulations and experiments confirm that the proposed topology is feasibility and the modulation is effective.
[1] 周玉斐, 黄文新, 赵萍. 三相耦合电感单级升压逆变器非隔离光伏并网发电系统[J]. 电工技术学报, 2015, 30(6): 190-199. Zhou Yufei, Huang Wenxin, Zhao Ping. A transfor-merless photovoltaic grid-connected system of three-phase single-stage boost inverter with coupled inductor[J]. Transactions of China Electrotechnical Society, 2015, 30(6): 190-199. [2] Islam M, Mekhilef S. H6-type transformer-less single-phase inverter for grid-tied photovoltaic system[J]. IET Power Electronics, 2015, 8(8): 636- 644. [3] Tang Yi, Yao Wenli, Loh P C. Highly reliable transformerless photovoltaic inverters with leakage current and pulsating power elimination[J]. IEEE Transactions on Industrial Electronics, 2016, 63(2): 1016-1026. [4] Kouro S, Leon J I, Vinnikov D, et al. Grid-connected photovoltaic systems: an overview of recent research and emerging PV converter technology[J]. IEEE Industrial Electronics Magazine, 2015, 9(1): 47-61. [5] 胡存刚, 姚培, 张云雷, 等. 高效非隔离单相并网MOSFET逆变器拓扑及控制策略[J]. 电工技术学报, 2016, 31(13): 82-91. Hu Cungang, Yao Pei, Zhang Yunlei, et al. Topology and control strategy for high-efficient non-isolated single-phase grid-connected MOSFET inverter[J]. Transactions of China Electrotechnical Society, 2016, 31(13): 82-91. [6] 郭小强, 魏宝泽, 杨秋霞, 等. 六开关光伏并网逆变器共模漏电流抑制方法[J]. 电力系统自动化, 2014, 38(14): 101-105. Guo Xiaoqiang, Wei Baoze, Yang Qiuxia, et al. Leakage current suppression method with a novel six switch photovoltaic grid-connected inverter[J]. Automation of Electric Power Systems, 2014, 38(14): 101-105. [7] Guo Xiaoqiang, Wang Huaibao, Lu Zhigang, et al. New inverter topology for ground current suppression in transformerless photovoltaic system application[J]. Journal of Modern Power System and Clean Energy, 2014, 2(2): 191-194. [8] Chen Wenjie, Yang Xu, Zhang Weiping, et al. Leakage current calculation for PV inverter system based on a parasitic capacitor model[J]. IEEE Transactions on Power Electronics, 2016, 31(2): 8205-8217. [9] Kerekes T, Liserre M, Teodorescu R, et al. Evaluation of three-phase transformerless photovoltaic inverter topologies[J]. IEEE Transactions on Power Electronics, 2009, 24(9): 2202-2211. [10] 杨晓光, 姜龙斌, 冯俊博, 等. 一种新型高效无变压器型单相光伏逆变器[J]. 电工技术学报, 2015, 30(8): 97-103. Yang Xiaoguang, Jiang Longbin, Feng Junbo, et al. A new high efficiency transformerless single-phase photovoltaic inverter[J]. Transactions of China Electro- technical Society, 2015, 30(8): 97-103. [11] 郭小强, 魏宝泽, 贾晓瑜, 等. FB10三相非隔离型光伏并网逆变器共模电流抑制研究[J]. 电工技术学报, 2015, 30(8): 136-142. Guo Xiaoqiang, Wei Baoze, Jia Xiaoyu, et al. Common mode current suppression for FB10 three-phase non-isolated PV grid-connected inverter[J]. Transactions of China Electrotechnical Society, 2015, 30(8): 136-142. [12] Liu Chuang, Wang Yixu, Cui Jianfeng, et al. Transfor-merless photovoltaic inverter based on interleaving high-frequency legs having bidirectional capability[J]. IEEE Transactions on Power Electronics, 2016, 31(2): 1131-1142. [13] Cha W J, Kim K T, Cho Y W, et al. Evaluation and analysis of transformerless photovoltaic inverter topology for efficiency improvement and reduction of leakage current[J]. IET Power Electronics, 2015, 8(2): 255-267. [14] Vázquez N, Rosas M, Hernández C, et al. A new common-mode transformerless photovoltaic inverter[J]. IEEE Transactions on Industrial Electronics, 2015, 62(10): 6381-6391. [15] Tan K S F, Rahim N A, Hes W P, et al. Comparison and analysis of single-phase transformerless grid-connected PV inverter[J]. IEEE Transactions on Power Electronics, 2014, 29(10): 5358-5369. [16] Nabae A, Akagi H, Takahashi I. A new neutral-point- clamped PWM inverter[J]. IEEE Transactions on Industry Applications, 1981, 17(5): 518-523. [17] Mostafa K, Hossein S, Keith C, et al. A generalized capacitor voltage balancing scheme for flying capacitor multilevel converters[C]//25th Annual IEEE Applied Power Electronics Conference and Exposition APEC Palm Springs, 2010: 58-62. [18] Sepahvand H, Liao J, Ferdowsi M. Investigation on capacitor voltage regulation in cascaded H-bridge multilevel converters with fundamental frequency switching[J]. IEEE Transactions on Industrial Electronics, 2011, 58(11): 5102-5111. [19] Bruckner T, Bernet S, Steimer P K. Feedforward loss control of three-level active NPC converters[J]. IEEE Transactions on Industry Applications, 2007, 43(6): 1588-1596. [20] Xiao Huafeng, Xie Shaojun. Transformerless split- inductor neutral point clamped three-level PV grid-connected inverter[J]. IEEE Transactions on Power Electronics, 2011, 27(4): 1799-1808. [21] 王金华, 顾云杰, 胡斯登, 等. 一种二极管无源钳位的单相无变压器型光伏并网逆变器拓扑研究[J]. 中国电机工程学报, 2015, 35(6): 1455-1462. Wang Jinhua, Gu Yunjie, Hu Sideng, et al. A single-phase diode clamped transformerless PV grid-connected inverter[J]. Proceeding of the CSEE, 2015, 35(6): 1455-1462. [22] Mei Ye, Hu Senjun, Lin Lei, et al. Highly efficient and reliable inverter concept-based transformerless photovoltaic inverters with tri-direction clamping cell for leakage current elimination[J]. IET Power Electronics, 2016, 9(8): 1675-1683. [23] Li Wuhua, Gu Yunjie, Luo Haoze, et al. Topology review and derivation methodology of single-phase transformerless photovoltaic inverters for leakage current suppression[J]. IEEE Transactions on Industrial Electronics, 2015, 62(7): 4537-4551. [24] Tan K S F, Rahim N A, Hew W, et al. Modulation techniques to reduce leakage current in three-phase transformerless H7 photovoltaic inverter[J]. IEEE Transactions on Industrial Electronics, 2015, 62(1): 322-331. [25] Yang Bo, Li Wuhua, Gu, Yunjie, et al. Improved transformer- less inverter with common-mode leakage current elimination for a photovoltaic grid-connected power system[J]. IEEE Transactions on Power Electronics, 2012, 27(2): 752-762. [26] Kerekes T, Teodorescu R, Borup U. Transformerless photovoltaic inverters connected to the grid [C]//IEEE Applied Power Electronics Conference, Anaheim, 2007: 1733-1737. [27] Ozkan Z, Hava A M. A survey and extension of high efficiency grid connected transformerless solar inverters with focus on leakage current characteristics[C]//IEEE ECCE, Raleigh 2012: 3453-3460. [28] Ozkan Z, Hava A M. Leakage current analysis of grid connected transformerless solar inverter with zero vector isolation[C]//IEEE ECCE, Phoenix, 2011: 2460-2466.
2018, Vol. 33 
