Model predictive control (MPC) is widely used in modular multilevel converter (MMC) control because of its strong robustness, fast dynamic response, and strong stability. Traditional MPC must traverse several switch combinations to accurately regulate the output current and circulating current of the MMC. Therefore, as the number of sub-module (SM) grows, the controller's computational complexity grows. This paper proposes a compensatory model predictive current control (CMPCC) for inner loop current control. It immediately estimates the number of SMs required by the bridge arm without scrolling optimization, reducing the amount of calculation of the system and improving the output current and circulating current tracking accuracy to the references. The objective function is established based on the system output current and internal circulation current by developing the discretization mathematical model of MMC. On the basis of minimizing the optimization scope, the compensation prediction is achieved through the volt-second balance, to achieve effective current control. Subsequently, an uneven bucket sorting algorithm is proposed to drastically eliminate the unnecessary sorting process. Finally, both a MATLAB/Simulink model and an experimental platform of MMC are built. To verify the practicality of the proposed control strategy, simulation and hardware experiments are provided.

At present, model predictive control (MPC) is widely used in power electronic converters. The objective function is typically utilized to select the optimal voltage vector, but the switching frequency is not fixed or too high during the selection process. Therefore, to address this issue, a novel optimal voltage vector selection control strategy for Vienna rectifier is proposed in this paper. Specifically, hysteresis link is introduced into finite control set-model predictive direct power control (FCS-MPDPC). The optimization criterion is changed from the traditional objective function tracking error minimization to the longest extension step in the hysteresis loop. As a result, the switching frequency can be reduced and the control algorithm can be simplified by redefining the optimization criteria of the rectifier output voltage vector. Moreover, according to the power control model of Vienna rectifier, three-level space vector pulse width modulation (SVPWM) is used to generate the switching function for the next cycle. Finally, an experimental platform for Vienna rectifier based on dSPACE hardware is built to verify the feasibility of the proposed strategy. Experimental results show that the control strategy can ensure the rectifier to run normally and exhibit good steady state performance.INDEX TERMS Vienna rectifier, optimal voltage vector selection, finite control set-model predictive direct power control, extension step, switching frequency.