Suppression Algorithm for Output Voltage Unbalance of Three-Level Inverters under Fault Tolerant Operation
Zhang Ming1, Guo Yuanbo2, Li Ze2, Zhang Xiaohua1, 2
1. School of Electrical Engineering & Automation Harbin Institute of Technology Harbin 150001 China; 2. School of Electrical Engineering Dalian University of Technology Dalian 116024 China
Abstract：In medium and high power drive application, the fault tolerance of three-level neutral- point-clamped (NPC) inverter has been deeply studied. However, the neutral-point (NP) voltage fluctuation of three-level NPC inverter under fault-tolerant operation is seldom discussed. Using eight-switch three-phase inverter (ESTPI) as the fault-tolerant topology, this paper firstly proves that the existence of NP voltage unbalance is inevitable. Furthermore, the fluctuation of NP voltage will cause the three-phase unbalance of output voltage. Thus, a suppression strategy for output voltage is proposed considering the NP voltage fluctuation. Experimental results show that the proposed method can suppress the three-phase unbalance of output voltage effectively, and the adjustment time is within one modulation period.
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2018, Vol. 33 
