Robust DC-Link Voltage-Balancing Strategy Based on Model Predictive Control

For single-phase three-level inverters, the neutral-point (NP) voltage balance problem must be solved to ensure normal operation. This brief proposes a robust voltage balance control method based on the model predictive control. The relative tracking errors of the grid current are used to judge which split capacitor voltage is larger. Then, the larger (smaller) split capacitor voltage will be used as the small vector when releasing power to the grid (absorbing power from the grid). Consequently, there is no need sampling the split capacitor voltages and the voltage sensors can be reduced. Besides, the NP voltage balance is well achieved even when the parameter drift happens to the grid inductor, which enhances the robustness. Finally, a T-type single-phase three-level grid-tied inverter platform is built to verify the effectiveness of the proposed control method.