DC-Link Voltage Balance Control Strategy Based on Multidimensional Modulation Technique for Quasi-Z-Source Cascaded Multilevel Inverter Photovoltaic Power System

2018 ◽  
Vol 14 (11) ◽  
pp. 4905-4915 ◽  
Author(s):  
Weihua Liang ◽  
Yushan Liu ◽  
Baoming Ge ◽  
Xilian Wang
2013 ◽  
Vol 756-759 ◽  
pp. 292-297
Author(s):  
Ming Ma ◽  
Gang Peng ◽  
Jun Wei Hao ◽  
Jing Jing Lu ◽  
Chang Yuan ◽  
...  

This paper discusses the establishing method of DC voltage of modular multilevel converter (MMC). Firstly the structure of MMC and the charging principle of sub-modules (SMs) are introduced in order to control the DC voltage of MMC and reduce the switching loss. It is pointed out that the DC voltage control in MMC includes two parts, the DC voltage establishment of system and the voltages control of SMs. For the DC voltage control in system, the control theory is analyzed, and the corresponding control strategy is proposed. Meanwhile an improved voltage balance control strategy for SM is proposed by the improvements of the traditional voltage sorting method to reduce the high switching frequency caused by the blind action of switching devices in the SM control. Finally, the simulation results based on PSCAD/EMTDC show that DC voltage in MMC can run in the rated value steadily, and the switching frequency is reduced significantly.


2013 ◽  
Vol 62 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Bo Gong ◽  
Shanmei Cheng ◽  
Yi Qin

Abstract The unbalance of the neutral point voltage is an inherent problem of three-level neutral-point-clamped (NPC) inverter, the effect of neutral point voltage balancing which is caused by voltage vector is analyzed, and the relationship of the voltage offset and neutral point voltage is studied in this paper. This paper proposes a novel neutral point balance strategy for three-level NPC inverter based on space vector pulse width modulation (SVPWM). A voltage offset is added to the modulation wave, and a closed-loop neutral point voltage balance control system is designed. In the control system, the dwelling time of synthesis voltage vectors for SVPWM is varied to solve the problem of the unbalance of the neutral point voltage, the sequence of the voltage vectors maintains unchanging. Simulation and experimental results show the neutral point voltage balancing control strategy based on SVPWM is effective.


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