Model Predictive Control of Non-Isolated DC/DC Modular Multilevel Converter Improving the Dynamic Response

The model predictive control (MPC) is a well-accepted method for controlling power electronic converters. This paper presents a tailored MPC approach in which the internal and external dynamics of the dc/dc modular multilevel converter (MMC) are integrated into the MPC algorithm. The proposed MPC approach introduces three control objectives to have full control over the internal and external dynamics. Each of the designed cost functions includes one primary term regulating one of the control objectives and one secondary term improving the converter performance. Unlike the conventional control approach based on multiple proportional-integral (PI) controllers, the proposed approach provides a straightforward way to design the control parameters. The operation of the presented MPC approach is thoroughly investigated and compared to that of the PI-based controller. Comparative simulation studies confirmed that the proposed MPC approach reduces the ac circulating current in the steady-state operation compared to the conventional PI-based control. In the transient mode, the MPC approach offers much smoother and faster responses to the changes in the power reference. The performance of the dc/dc MMC controlled by the proposed MPC approach under parametric uncertainty is investigated, and improved performance is obtained compared to the conventional PI-based control.