Research on the Neutral-Point Voltage Balance for NPC Three-Level Inverters under Non-Ideal Grid Conditions

Jian Guo Lyu, Ji Dong Wang, Wen Bin Hu and Zhao Feng Wu
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Jian Guo Lyu: Nanjing University of Science and Technology, Nanjing 210094, China
Ji Dong Wang: Nanjing University of Science and Technology, Nanjing 210094, China
Wen Bin Hu: Nanjing University of Science and Technology, Nanjing 210094, China
Zhao Feng Wu: Nanjing University of Science and Technology, Nanjing 210094, China

Energies, 2018, vol. 11, issue 6, 1-21

Abstract: In order to solve the neutral-point voltage unbalancing problem for neutral-point clamped (NPC) three-level inverters under non-ideal grid conditions, a novel zero-sequence component injection method for modulation signals was proposed in this paper. Based on the mathematical expressions of neutral-point voltage unbalancing, the fluctuation of the neutral-point voltage under different grid conditions was studied. The proposed method dynamically calculates the zero-sequence component for modulation signals by region selections based on sinusoidal pulse width modulation (DCR-SPWM). Under non-ideal grid conditions, this DCR-SPWM method can control the neutral-point voltage balance for NPC three-level inverters with different grid and output power conditions, and improves the grid current quality. The simulation results verified the correctness of the theoretical analysis in this paper, and the feasibility and effectiveness of this method were verified by the experiments in the experimental platform of the NPC three-level grid-connected inverter based on DSP-CPLD controllers.

Keywords: non-ideal grid; three-level inverters; neutral-point voltage balance; modulation signals; region selection (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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