An Improved Method to Reduce the Number of Sensors in the Modular Multilevel Converters (MMCs)

Abstract – In this paper, the combination of a new capacitor voltages sorting method as well as an open-loop control method based on arms energy estimation in the modular multilevel converter (MMC) is used. Problems related to MMC, such as circulating current, using various voltage and current sensors, as well as capacitor voltage imbalances, increase the cost and complexity of using the converter. The proposed sensor reduction method offers using only two voltage sensors in the arms and one current sensor at the output terminal. Arm parameters are simply estimated using circuit-based relations. The circulating current of the converter is controlled at a DC level using an energy estimation based on the open-loop control method. Using this method, the converter’s arms currents can be determined only based on the output terminal current sensor. In addition, the voltages of the capacitors keep constant without using any additional voltage sensor for each submodule. The effectiveness of the proposed method is verified by software simulations.

Keywords—Energy balance, sorting method, sensor reduction, modular multilevel converter

Leave A Comment

Your email address will not be published. Required fields are marked *