Hierarchical Model Predictive Control for Cascaded Multilevel Inverters

This paper presents a hierarchical finite-set model predictive control (MPC) scheme for grid-tied cascaded multilevel inverters (CMI) with independent active and reactive power injection capabilities. The proposed controller has a hierarchical framework to eliminate the computationally burdensome cost function optimization and associated weight factors of the control objectives. The control formulation approach allows for multi-objective optimization with an error-tolerance framework. The control scheme achieves active and reactive power control with switching loss minimization while extracting power evenly from the independent voltage sources. The control is modularized for each phase, making the system robust to unbalanced grid conditions. The proposed control scheme is validated for grid-voltage transients in MATLAB/Simulink.