Investigation of modular multilevel converter control methods

Ertürk, Feyzullah
The thesis focuses on the analysis and control of modular multilevel converter (MMC). The control structures used in the control of MMC are presented. Outer control loops of the converter such as output current, DC-link voltage, and power controls as well as inner control structures unique to the converter such as circulating current control and sorting algorithm based submodule voltage balancing are investigated. In addition, switching methods proposed for MMC are also described. These control and switching methods are examined on a sample DC/AC MMC and their effects are evaluated. In addition, parameters such as circulating current control, sorting algorithm based submodule voltage balancing, modulation methods, used in MMC control, as well as power factor are evaluated on their effects over semiconductor power loss in the system via detailed analysis. Total system loss and individual semiconductor loss are dwelled on. Later, the applicability in HVDC is inspected on a sample back-to-back MMC system and a method to improve dynamic operation is proposed. After the shortcomings of MMC in low-frequency operation are described, the control method that allows MMC to be used in motor drive application is explained and applied in a sample system via simulation. The study is realized by mathematical analysis, topological design, controller design and detailed computer simulation.


Selection of suitable PWM switching and control methods for modular multilevel converter drives /
Çiftçi, Barış; Hava, Ahmet Masum; Department of Electrical and Electronics Engineering (2014)
The thesis focuses on the determination of suitable carrier based PWM switching and control method for modular multilevel converter drives. Characterization of various level-shifted and phase-shifted carrier based PWM methods are provided in terms of switching pulse patterns and resultant voltage waveforms both for N+1 and 2N+1 level output phase voltages. Modular multilevel converter PWM based control approaches are evaluated. Performances of different control methods are given for output harmonics distort...
Adaptive control of DC link current in current source converter based STATCOM for improving its power losses
Karaduman, Ferdi; Ermiş, Muammer; Bilgin, Hazım Faruk; Department of Electrical and Electronics Engineering (2012)
In conventional three-phase PWM (Pulse Width Modulation) current source converter based STATCOM (Static Synchronous Compensator) applications, DC link current is kept constant at a predefined value and the reactive power of STATCOM is controlled by varying modulation index. This control strategy causes unnecessary power losses especially when the reactive power of STATCOM is low. For this purpose, in order to reduce the active power drawn by STATCOM, the modulation index can be maximized by adjusting DC lin...
FPGA implementation of field oriented control forpermanent magnet synchronous motor
Irmak, Gizem; Saranlı, Afşar; Department of Electrical and Electronics Engineering (2019)
The thesis study focuses on the fully operational FPGA implementation for the current/torque control of a Permanent Magnet Synchronous Motor. 3-phase synchronous motors with permanent magnets can be categorized into two categories as Permanent Magnet Synchronous Motor (PMSM) and Brushless Direct Current (BLDC) motor. The main difference between PMSM and BLDC is the shape of the induced back-EMF voltage. While BLDC motors have trapezoidal shaped back-EMF, PMSMs have a sinusoidal back-EMF. In order to take ad...
Design and implementation of a current source converter based statcom for reactive power compensation
Bilgin, Hazım Faruk; Ermiş, Muammer; Department of Electrical and Electronics Engineering (2007)
This research work is devoted to the analysis, design and development of the first medium power Current-Source Converter (CSC) based distribution-type Static Synchronous Compensator (D-STATCOM) with simplest converter topology and coupling transformer connection. The developed CSC-D-STATCOM includes a +/-750kVAr full-bridge CSC employing Selective Harmonic Elimination Method (SHEM), a 250kVAr low-pass input filter at 1kV voltage level, and a Δ/Y connected coupling transformer for connection to medium-voltag...
An FPA based BLDC motor control system
Uygur, Serdar; Güran, Hasan Cengiz; Department of Electrical and Electronics Engineering (2012)
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Citation Formats
F. Ertürk, “Investigation of modular multilevel converter control methods,” M.S. - Master of Science, Middle East Technical University, 2015.