Modular Multilevel Converter With Different Submodule Concepts-Part I: Capacitor Voltage Balancing Method

• Published in: IEEE transactions on industrial electronics (1982) Vol. 60; no. 10; pp. 4525 - 4535
• Main Authors: Solas, E., Abad, G., Barrena, J. A., Aurtenetxea, S., Carcar, A., Zajac, L.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2013; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Capacitor voltage balancing control; Capacitors; Converters; Electric potential; HVDC; IGBTs; Insulated gate bipolar transistors; Metal matrix composites; Modular; modular multilevel converter (MMC); Modulation; multilevel converter topologies; Pulse width modulation; pulse width modulation (PWM); Strategy; Studies; submodule concept; Switches; Topology; Voltage control
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2012.2210378

This paper presents a modulation strategy for the modular multilevel converter (MMC) which provides the voltage balancing of the capacitors of different submodules comprising the converter. Not only is this modulation applicable to MMCs constructed with classic two level (2L) submodules, but it is also effective for arrangements with different submodule concepts, for instance, topologies like neutral point clamped (NPC), flying capacitors (FCs), neutral point piloted (NPP), etc. Therefore, firstly, the general modulation philosophy is explained applied to the two level (2L) submodule concept, and secondly, the extension to 3L-NPC and 3L-FC submodule topologies is analyzed. After that, the validation of the studied modulation strategy is carried out by means of successful simulation results, at different switching frequencies and number of submodules. The corresponding experimental results are shown in Part II of this paper after having implemented the aforementioned modulation strategy in a real test bench. In addition to this, a comparison based on thermal analysis and sizing of elements among the four studied submodule topologies is also included.