Finite-Level-State Model Predictive Control for Sensorless Three-Phase Four-Arm Modular Multilevel Converter

This letter focuses on a finite-level-state model predictive control strategy for sensorless three-phase four-arm modular multilevel converter (MMC). The aim of this letter is to enhance the reliability of the whole system under the arm and sensor fault conditions. First, a three-phase four-arm MMC topology, which has a good potential to further improve the fault tolerance ability of the MMC, is presented. Next, a novel control strategy for sensorless three-phase four-arm MMC is proposed by combining an adaptive linear-neuron-based submodule voltage estimation scheme with a currentless sorting-based capacitor-voltage-balancing approach. Thus, the complexity of the control system and the associated costs can be reduced. Finally, comprehensive experiments are conducted to demonstrate the effectiveness and feasibility of the proposed methodology for three-phase four-arm MMC.