A Single-Objective Modulated Model Predictive Control for a Multilevel Flying-Capacitor Converter in a DC Microgrid

This article presents a single-objective modulated model predictive control for a bidirectional dc–dc flying-capacitor (FC) converter in a microgrid. The presence of an FC facilitates the converter to integrate a low-voltage battery to a high-voltage dc bus at reduced voltage stress on its power switches. The converter in such a configuration demands a multiobjective controller to accomplish dc bus and FC voltage regulations and bidirectional power flow. The proposed controller realizes these multiple control objectives by determining the optimum duty ratio for the power switches using a single-objective cost function based on the battery current. In doing so, the converter realizes its multiple control objectives without weighting factors in the cost function and operates its power switches at a fixed switching frequency. The proposed controller also eliminates an additional control loop by utilizing an improved dynamic reference model to generate an appropriate battery current reference for the dc bus voltage regulation and bidirectional power flow. Finally, the proposed system is validated experimentally under step response of the dc bus voltage, load, PV power, and system parameter variations, and compared with a finite control set model predictive control to prove its effectiveness.