Space-Vector-Equalized Predictive Current Control Scheme for the Modular Multilevel Converter With Improved Steady-State Performance

A large number of control options and steady-state tracking errors are two main challenges for model predictive control in the modular multilevel converter (MMC). To solve these issues, each arm of the three-phase MMC is considered as a whole, and a space-vector-equalized predictive current control scheme is proposed for the three-phase MMC in this article. First, eight equalized space vectors are involved, and only six nonzero vectors are evaluated in each period. As a result, the number of evaluated control options can be significantly reduced. Then, two optimal vectors are selected, and their dwell times are calculated based on the predicted output currents of the MMC. Furthermore, the compensation terms are designed and added to the dwell times so that the steady-state performance can be improved by the proposed scheme. Experimental results show that the proposed scheme provides fast dynamic response and outstanding steady-state performance for the three-phase MMC.