Improved Model Predictive Control Method for the Reduced Active Switch Count Three-Level Rectifier with Unbalanced Neutral-Point Voltage Conditions

The control of reduced active switch count (RASC) three-level rectifier presents significant challenges under unbalanced dc links. To mitigate dc link voltage imbalances, the improved model predictive control (MPC) achieves neutral-point voltage regulation through strategic preselection of redundant small vectors in switching state optimization. To reduce the computational burden, an optimal sector-based optimization algorithm is proposed, which streamlines the vector selection process. Furthermore, the weighting factor is eliminated by strategically utilizing small vectors in the switching state selection. Finally, simulation studies ultimately corroborate the validity of the proposed control scheme. The presented approach achieves enhanced transient-regime behavior while maintaining stable steady-state operation.