Improved Predictive Control of Three-Level-NPC Power Converters

This paper presents the results of a study on a neutral-point voltage balancing scheme applied to three-level neutral point clamped (NPC) power converters. The proposed control method was executed within the model predictive control (MPC) framework. The usual means of maintaining the accuracy of current in MPC schemes employ the use of a weighting factor to account for the compromise with effective neutral point voltage balance and reference tracking. In this work, we present a different method that decouples the current and neutral point voltage balance, avoiding the use of a weighting factor. This new method resulted in a 29.9% reduction in the assessment of the switching states and there is no necessary to predict the DC link voltage. We validate our control method using simulation data and experimental studies. It demonstrates the ability of proposed approach to decrease computational costs and enhance the system performance, such as better neutral voltage balancing capabilities, faster DC-link voltage control dynamic, and smaller total harmonic distortions total harmonic distortion (THD) in both the phase current and voltage.