Novel single‐armed modular multilevel converter for reducing total converter capacitance

Abstract

Abstract During normal operation of a conventional Modular Multilevel Converter (MMC), half of its capacitors remain bypassed at any time instant, increasing the total required capacitance for converter operation, and in turn leading to a larger size and volume MMC for a target capacitor voltage ripple limit. This paper presents a novel MMC topology that utilizes all converter capacitors at all times during the operation. Therefore, the total required capacitance for generating a voltage waveform with the same number of levels and the same target capacitor voltage ripple limit is greatly reduced compared to conventional MMCs. The new topology inherits all the desirable features of conventional MMCs such as modularity, reliability, and scalability, and is compatible with many of the previously proposed control techniques for conventional MMCs. The process of synthesizing the proposed MMC topology and a new voltage balancing scheme as well as the dynamic model and capacitor sizing procedure for the proposed MMC are reported in the paper. Furthermore, experimental results are presented to evaluate the performance of the proposed converter.

Keywords

• Power electronics, supply and supervisory circuits
• Voltage control
• Control of electric power systems
• Capacitors
• AC‐DC power convertors (rectifiers)
• DC‐AC power convertors (invertors)