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A Modulation Strategy Based on Modulation Wave Decomposition for Neutral Point Clamped Three-Level Inverter |
Wang Jinping, Liu Bin, Dong Hao, Jiang Weidong |
School of Electrical Engineering and Automation Hefei University of Technology Hefei 230009 China |
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Abstract Compared with the two-level inverter, the neutral point clamped three-level inverter (NPC TLI) has the advantages of low electromagnetic interference, low voltage stress of switching devices, and low total harmonic distortion (THD). Therefore, it is widely used in renewable energy generation, the transmission of high voltage and high power, medium/high voltage variable frequency motor drives, and so on. Carrier-based pulse width modulation (CBPWM) method and space vector pulse width modulation (SVPWM) method are usually applied to NPC TLI, which are equivalent to a certain extent. CBPWM generates PWM sequences by comparing double carriers and single modulation waves. In this paper, the carrier of CBPWM is optimized by replacing double carriers with a single carrier. Then, the modulation wave is processed to eliminate the negative value. Accordingly, this paper proposes a modulation wave decomposition method and applies it to virtual space vector pulse width modulation (VSVPWM). The neutral point voltage (NPV) can still be unconditionally balanced under VSVPWM with this method, which proves the feasibility of the method. Compared with CBPWM, the switching loss is increased when VSVPWM is used, even though NPV can be unconditionally balanced, which greatly affects the power conversion efficiency of the inverter. Six modulation waves can be obtained when VSVPWM with the proposed method of modulation wave decomposition is used, and two of them are clamped. Limiting the modulation wave that is not clamped reduces the switching action of a specific phase and the switching loss. Four modes can be obtained after the modulation waves are limited, so this method is named FM_VSVPWM in this paper. Compared with VSVPWM, when the proposed FM_VSVPWM is used, the switching loss can be effectively reduced, and NPV can also be balanced in the full range of modulation index and power factor. The steady-state experimental results show that when the modulation index is 0.9, and the power factor is 0.26. NPV fluctuates with triple fundamental frequency, and the fluctuation amplitude is about 6 % of the DC link voltage when CBPWM is used. When VSVPWM and the proposed FM_VSVPWM are used, NPV can always be balanced in the full range of modulation index and power factor. In addition, the switching losses of the above three methods are compared in this paper. Compared with VSVPWM, when FM_VSVPWM is used, the switching losses are reduced by 13 %, which proves the superiority of the proposed FM_VSVPWM in reducing switching loss. The NPV recovery experimental result shows that even if there is a 10 % offset on the DC link capacitor voltage, NPV can still recover quickly. The dynamic experimental results include the sudden change of modulation index and the sudden change of load. The results show that when FM_VSVPWM is used, NPV can keep balance when external interference is added. Moreover, the current THD of the three methods is compared. The results show that when the modulation index is low, compared with VSVPWM, the current THD of FM_VSVPWM decreases from 11.8 % to 8.5 %.
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Received: 23 May 2022
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[1] 高瞻, 李耀华, 葛琼璇, 等. 一种三电平中点钳位变流器改进型载波反相层叠脉宽调制策略[J]. 电工技术学报, 2021, 36(4): 831-842. Gao Zhan, Li Yaohua, Ge Qiongxuan, et al.Improved phase opposition disposition pulse width modulation strategy for three-level neutral point clamped converter[J]. Transactions of China Electrotechnical Society, 2021, 36(4): 831-842. [2] Wang Rutian, Ai Lan, Liu Chuang.A novel three-phase dual-output neutral-point-clamped three-level inverter[J]. IEEE Transactions on Power Electronics, 2021, 36(7): 7576-7586. [3] 孟庆云, 晏明, 潘启军, 等. 一种适用于大容量中点钳位型三电平逆变器的绝缘栅双极型晶体管吸收电路研究[J]. 中国电机工程学报, 2016, 36(3): 755-764. Meng Qingyun, Yan Ming, Pan Qijun, et al.Research on a insulated gate bipolar transistor snubber circuit for the high power neutral point clamped three-level inverter[J]. Proceedings of the CSEE, 2016, 36(3): 755-764. [4] He Jinkui, Sangwongwanich A, Yang Yongheng, et al.Lifetime evaluation of three-level inverters for 1500V photovoltaic systems[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2021, 9(4): 4285-4298. [5] 邱继浪, 何英杰, 焦乾明, 等. 非隔离型三电平逆变器漏电流抑制与中点电位平衡控制[J]. 电力系统自动化, 2021, 45(17): 161-170. Qiu Jilang, He Yingjie, Jiao Qianming, et al.Leakage current suppression and balance control of neutral point potential for three-level transformerless inver-ter[J]. Automation of Electric Power Systems, 2021, 45(17): 161-170. [6] 罗锐, 何英杰, 陈晖, 等. 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, et al.SVPWM scheme for three-level converters with neutral-point potential balancing and switching loss reduction[J]. Transactions of China Electrotechnical Society, 2018, 33(14): 3245-3254. [7] 张建忠, 胡路才, 徐帅. 一种零序电压注入的T型三电平逆变器中点电位平衡控制方法[J]. 电工技术学报, 2020, 35(4): 807-816. Zhang Jianzhong, Hu Lucai, Xu Shuai.Neutral potential balance control method of T-type three-level inverter with zero-sequence voltage injection[J]. Transactions of China Electrotechnical Society, 2020, 35(4): 807-816. [8] 高瞻, 李耀华, 葛琼璇, 等. 适用于大功率三电平中点钳位整流器的SVPWM和DPWM策略研究[J].电工技术学报, 2020, 35(23): 4864-4876. Gao Zhan, Li Yaohua, Ge Qiongxuan, et al.Research on SVPWM and DPWM strategies suitable for high power three-level neutral point clamped rectifier[J]. Transactions of China Electrotechnical Society, 2020, 35(23): 4864-4876. [9] 刘云峰, 何英杰, 程瑞琪, 等. 单相二极管箝位多电平逆变器CBPWM与SVPWM调制策略的等效关系[J]. 电机与控制学报, 2020, 24(9): 13-21. Liu Yunfeng, He Yingjie, Cheng Ruiqi, et al.Equivalent relationship between carrier-based and space vector PWM strategy in single phase NPC multi-level inverter[J]. Electric Machines and Control, 2020, 24(9): 13-21. [10] 方辉, 宋文胜, 冯晓云, 等. 三电平SVPWM与CBPWM算法的内在联系研究[J]. 电工技术学报, 2014, 29(10): 19-26. Fang Hui, Song Wensheng, Feng Xiaoyun, et al.Relationship between three-level SVPWM and CBPWM[J]. Transactions of China Electrotechnical Society, 2014, 29(10): 19-26. [11] Busquets-Monge S, Bordonau J, Boroyevich D, et al.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. [12] Wan Wenchao, Duan Shanxu, Chen Changsong, et al.A hybrid control method for neutral-point voltage balancing in three-level inverters[J]. IEEE Transa-ctions on Power Electronics, 2021, 36(8): 8575-8582. [13] Liu Peng, Duan Shanxu, Yao Chuan, et al.A double modulation wave CBPWM strategy providing neutral-point voltage oscillation elimination and CMV reduction for three-level NPC inverters[J]. IEEE Transactions on Industrial Electronics, 2018, 65(1): 16-26. [14] Xia Shuai, Wu Xiaojia, Zheng Jinggang, et al.A virtual space vector PWM with active neutral point voltage control and common mode voltage suppression for three-level NPC converters[J]. IEEE Transactions on Industrial Electronics, 2021, 68(12): 11761-11771. [15] 李敏裕, 马晓军, 魏曙光, 等. 三电平虚拟空间矢量脉宽调制算法窄脉冲抑制研究[J]. 电工技术学报, 2018, 33(14): 3264-3273. Li Minyu, Ma Xiaojun, Wei Shuguang, et al.Research on narrow pulse suppression of three-level virtual space vector pulse width modulation algorithm[J]. Transactions of China Electrotechnical Society, 2018, 33(14): 3264-3273. [16] An S, Lee K.A reliability improvement method for three-level inverters with modified VSVPWM[C]//IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW), Seoul, Korea (South), 2020: 184-188. [17] Jiang Weidong, Wang Peidong, Ma Mingna, et al.A novel virtual space vector modulation with reduced common-mode voltage and eliminated neutral point voltage oscillation for neutral point clamped three-level inverter[J]. IEEE Transactions on Industrial Electronics, 2020, 67(2): 884-894. [18] Wang Jinping, Gui Zaiyi, Wang Peixia, et al.A carrier-based modulation with planned zero sequence voltage injection to control neutral point voltage for three-level inverter[J]. IEEE Access, 2020, 8: 64799-64809. [19] Jiang Weidong, Jiang Haoran, Liu Shengyu, et al.A carrier-based discontinuous PWM strategy for T-type three-level converter with reduced common mode voltage, switching loss, and neutral point voltage control[J]. IEEE Transactions on Power Electronics, 2022, 37(2): 1761-1771. |
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