The modular multilevel converter (MMC) has become the most attractive multilevel converter topology for medium/high-power applications, specifically for voltage-sourced converter high-voltage direct current (VSC–HVDC) transmission systems. In comparison with other multilevel converter topologies, the salient features of the MMC include:
1) Modularity and scalability to meet any voltage level requirements,
2) High efficiency, which is of significant importance for high-power applications,
3) Superior harmonic performance, specifically in high-voltage applications where a large number of identical submodules (SMs) with low-voltage ratings are stacked up, thereby the size of passive filters can be reduced, and
4) Absence of dc-link capacitors.
Over the past few years, there has been a significant effort towards addressing the technical challenges associated with the operation and control of the MMC as well as broadening its applications.
The main intention of this MOOC is to introduce the MMC topology and its operational and control challenges along with the most recent solutions to address those challenges.
Module 1: Basics of Inverters
Principles of operation of single-phase and three-phase DC-AC inverters, Space phasors and alpha-beta reference frame, Space vector modulation for three-phase inverters, Current control mode of inverters
Module 2: Modeling and Control of Grid-Connected Inverters
Modeling of three-phase grid-connected inverters, Closed-loop control of three-phase inverters
Module 3: Multilevel Converters
Basics of multilevel converters, Various multilevel converter topologies
Module 4: Modular Multilevel Converters
Basics of cascaded half-bridge and full-bridge modules, Control aspects of the modular multilevel converter, Circulating current control
Module 5: Control of Grid-Connected Modular Multilevel Converters
Control of grid-connected modular multilevel converter, Control of the MMC for High-Voltage DC (HVDC) transmission