Hierarchical Single-Objective Model Predictive Control With Reduced Computational Burden in Cascaded H-Bridge Converter Based on 3-Level Flying Capacitor Unit Cell

This paper presents a control algorithm to reduce the computational burden of model predictive in grid-connected single-phase N-cell cascaded flying capacitor H-bridge (CFCHB) multilevel converter solid-state transformer. The proposed is finite-control-set (FCS-MPC) that based on hierarchical structure controlling grid current, DC-link voltage, and using each cost function through three layers. Unlike conventional multi objective evaluates compares all candidates determine optimal state, method uses single-objective by separating variables state calculation without comparison. Therefore, amount computation significantly reduced compared with method, execution time shortened. Thus, sampling period can be shortened switching frequency increased. Further, it lead smaller inductor produce high-quality which help system size cost. not large, even if voltage level increases effect reduction large existing because linearly proportional number cells. expansion easy suitable for digital implementation, performance affected. effectiveness verified simulation 250 kW 9-cell CFCHB PSIM an experiment 2 3-cell at laboratory scale.