Model Predictive Circulating Current Regulator for Single-Phase Modular Multilevel Converter

This paper describes a model predictive strategy to reduce the sub-module voltage oscillation in a single-phase modular multi-level converter. This task is accomplished by a predictive controller which solves an optimal control problem sequentially. By choosing the objective function weights appropriately, this controller can naturally trade-off sub-modules voltage ripple and recirculating current. It is shown that the sub-module voltage oscillation can be reduced without degrading the efficiency excessively, enhancing the performance of the overall converter. Additionally, it is guaranteed that the recirculating current can be regulated without exceeding the physical limitations of the device.