Zoning Deadbeat Model Predictive Control with Virtual Voltage Vectors for Current Control and Capacitor Voltage Balancing in the 3L-NPC

In this paper, two new methods for load current control and capacitor voltage balancing in the three-level neutral point diode clamped inverters (3L-NPC) are presented, which can be generalized to other control variables such as speed in electrical motors. In the first method, after calculating the required reference voltage vector, the K coefficient (with feedback from the upper capacitor voltage) and virtual voltage vectors were used to control the voltage of the capacitor. Using the K coefficient and virtual voltage vector in each sampling time causes the entire sector surface to include the reference voltage vector, which consists of voltage vectors that will have a positive effect or be ineffective. In the second method, the zoning deadbeat model predictive control is introduced, which is based on eliminating the voltage-based cost function in the simplified finite-set model predictive control. The closest voltage vector to the reference voltage vector is selected directly and without any cost function, which reduces the complexity and the computation burden. Therefore, using these two methods, there is no need for any cost function, modulators, weighting factor adjustment, or capacitor voltage prediction. Simulation results confirm the validity of these two methods.