Modulated Model Predictive Control of Modular Multilevel Converters Operating in a Wide Frequency Range

Abstract

The finite control set model predictive control (FCS-MPC), which considers corresponding instantaneous power in the cost function, becomes a promising solution that allows modular multilevel converters (MMCs) to operate in a wide frequency range due to its ability to balance the internal energy. However, FCS-MPC usually suffers from a heavy computational burden. The modulated MPC, which combines modulation techniques with MPC methods, is usually employed to overcome such a challenge. In this paper, we propose an exhaustive active-set method to implement the modulated MPC scheme enabling the MMC to operate over a wide frequency range. With the proposed method, the optimal solution can be obtained by enumerating all possible active sets rather than iterating, so the worst-case computational burden (or calculation time) can be determined. Finally, a comparative study of our proposed method with conventional modulated MPC methods and FCS-MPC has been conducted to demonstrate the effectiveness of the proposed method.