Towards Unified Model Predictive Control (MPC) Strategies in Power Electronics: A Review of FCS-MPC and CCS-MPC for DC-DC Buck Converters

In this paper, a unified analysis and a literature review on Model Predictive Control (MPC) strategies of DC-DC buck converters have been presented with particular emphasis on fixed switching frequency operation. With increasing requirements of high efficiency, low ripple and robust voltage regulation in modern power electronics applications, the traditional PID controllers can be inadequate in terms of dealing with nonlinearities and constraints. In this regard, two major types of MPC, that is, Finite Control Set MPC (FCS- MPC) and Continuous Control Set MPC (CCS-MPC) have also been introduced as valid alternates. Their control philosophies, modelling techniques, formulations of cost functions, and implementation issues are systematically reviewed in this paper. Special focus is given to measures that reduce the variable switching frequency of FCS-MPC that is inherent to it and the computational cost of CCS-MPC by building on recent developments, including modulated FCS-MPC, explicit MPC, and solver-light Quadratic Programming implementations. The proposal of a theoretical framework of a unified controller that incorporates the advantages of both approaches is also provided. Although the simulation performance graphs are given, according to the expected system dynamics and controller design concepts, it is still a future goal to validate the experiments. This review will help researchers and engineers to obtain actionable information on how to choose or hybridize MPC strategies in real-time embedded power systems by summarizing the findings of more than a decade of MPC research.