Abstract:DC capacitor voltage balance is one of the key issues in the control of five-level NPC (neutral point clamped) converter. In this paper, it analyses the influence of space vectors to the DC voltage balance in five-level NPC converter SVM(space vector modulation) strategy and explains the control thought of using different scheme to realize five-level SVM strategy in different modulation ratio region. Furthermore, it presents a novel DC capacitor voltage self-balancing SVM strategy of five-level NPC converter. The novel strategy divides the whole five-level space vector diagram into low modulation ratio region(mSV≤0.5) and high modulation ratio region(mSV>0.5). In low modulation region, it presents a DC capacitor voltage self-balancing SVM strategy which combines objective function scheme with reference voltage decomposition scheme. In high modulation area, it achieves DC capacitor voltage self-balancing SVM strategy by applying an optimal balancing vector selection (OBVS) scheme. Simulation and experimental results verify the DC voltage balancing characteristics of the proposed five-level NPC SVM strategy. The novel SVM strategy also has the characteristics of smaller amount of calculation, much simpler realization and better control effect.
李宁,王跃,厉肃,姚为正,张建,刘刚,王兆安. 直流电容电压自平衡的新型五电平NPC变流器空间矢量调制策略[J]. 电工技术学报, 2015, 30(6): 178-189.
Li Ning,Wang Yue,Li Su,Yao Weizheng,Zhang Jian,Liu Gang,Wang Zhaoan. DC Capacitor Voltage Self-Balancing Space Vector Modulation Strategy of Five-Level NPC Converter. Transactions of China Electrotechnical Society, 2015, 30(6): 178-189.
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