Selective Harmonic Mitigation — Model Predictive Control for a Grid-Connected Seven-Level Cascaded H-Bridge Converter

This paper proposes a Selective Harmonic Mitigation - Model Predictive Control (SHM-MPC) strategy applied to a grid-connected seven-level Cascaded H-Bridge (7L-CHB) converter. First, the switching angles for the SHM-MPC control problem formulation are designed to minimize the output voltage THD over the entire modulation index; second, the cost function is formulated to track a given grid-current reference while adding two additional terms that use the SHM-PWM voltage pattern and penalize the switching effort. Simulation results are presented showing the capability to accurately track the grid-current reference while moving through the non-linear regions of the switching angle solutions. The results show that SHM-MPC for grid-connected high-power converters secures the quality of the injected power by unifying the advantages of FCS-MPC i.e. high-bandwidth and SHM-PWM i.e. minimum switching effort and harmonic compliance even under high variable dynamic conditions.