Finite-set model predictive control and DC-link capacitor voltages balancing for three-level NPC inverters

This paper presents a finite control set model predictive strategy for a three-phase, three-level Neutral-Point-Clamped (NPC) inverters with resistive-inductive load (RL-Load). This strategy allows for fast load current control while keeping the balance of the DC-link capacitor voltages. The system performance with a prediction horizon of one sample time and the dynamic response of the system with step change in the amplitude of the reference are investigated. The output currents and DC-link capacitor voltages are sampled and predicted for the next sampling time for each valid switching state of the inverter. The error between the predicted and reference current values and also the error between the capacitor voltages with respect to the reference value are obtained to minimize the cost function by choosing the appropriate state´s switching signals and then applied to the converter. The simulation is carried out using MATLAB/Simulink with PSIM software. The co-simulation results show that the proposed control achieves high performance and high degree of robustness while balancing the DC-link capacitor voltages.