Publication: A space-vector PWM-Based Voltage-Balancing approach with reduced current sensors for modular multilevel converter
No Thumbnail Available
Date
2016
Authors
Dr. Lizana-Fuentes, Ricardo
Dekka, Apparao
Wu, Bin
Zargari, Navid
Journal Title
Journal ISSN
Volume Title
Publisher
IEEE Transactions on Industrial Electronics
Abstract
Arm voltage and submodule (SM) capacitor voltage balancing is a key factor for the safe and reliable operation of modular multilevel converters (MMCs). The arm voltage balancing is achieved through a zero-sequence voltage controller in carrier pulse-width modulation (CPWM). In this study, a dual space-vector pulse-width modulation (SVPWM) technique is proposed for an MMC, which eliminates the external controller for arm voltage balancing. In this approach, the three-phase top and bottom arms are independently controlled using SVPWM. In addition, the capacitor voltage balancing can be achieved using redundant switching vectors. However, this will increase the computational load on the space-vector modulator. Therefore, an external capacitor voltage-balancing approach is proposed to minimize the computational complexity. The proposed approach uses the direction of load current instead of the arm current in SM selection process. As such, the required number of current sensors is reduced to 50% in a three-phase system. The proposed modulation and voltage-balancing approach are simulated and experimentally verified on the MMC system with three-level flying capacitor (3L-FC) SMs. Simulation and experimental results show the successful balancing of the arm voltage and SM capacitors voltage.
Description
Keywords
Modular multilevel converter (MMC), Voltage balancing, Space vector pulse width modulation, Three-level flying capacitor (3L-FC)