Neutral Point Potential Balance Strategy for NPC Three-level Inverter Based on Meticulous Partition Control
Wang Huimin1, Wen Kunpeng1, Zhang Yun2, Xia Changliang1,2
1. Tianjin Key Laboratory of Advanced Electrical Engineering and Energy Technology Tianjin Polytechnic University Tianjin 00387 China; 2.School of Electrical Engineering and Automation Tianjin University Tianjin 300072 China
Abstract To solve the problem of neutral point potential fluctuation of neutral point clamped (NPC) three-level inverter,a meticulous partition control strategy is proposed based on the three vectors and four states synthetic method.In the low modulation degree,the amplitude of the duty cycle distribution factor is limited in order to eliminate the neutral point current.In the high modulation degree,through analyzing the judgment difference between extreme current value method and distribution factor method,the working area is divided to controllable interval (CI),uncontrollable interval (UI),and doubtful interval (DI).The adscription of DI is analyzed based on the control effect of the neutral point current,which minimize the neutral point current without increasing the operating frequency.By these,the neutral point potential fluctuation can be decreased with a low switching frequency,which is verified by the results of the simulations and experiments.
Wang Huimin,Wen Kunpeng,Zhang Yun等. Neutral Point Potential Balance Strategy for NPC Three-level Inverter Based on Meticulous Partition Control[J]. Transactions of China Electrotechnical Society, 2015, 30(19): 144-150.
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2015, Vol. 30 
