Improved Model Predictive Control for Asymmetric T-Type NPC 3-Level Inverter

Abstract

In this paper, a model predictive control for an asymmetric T-type NPC 3-level inverter is presented. The mathematical model and characteristics of the reduced switching topology are described. An improvement for the predicted strategy with the pre-selected candidate vectors is proposed. The simulation and experimental results are provided and show good efficiency for the proposed control algorithm. The improved algorithm greatly reduces execution time by about 18% and delivers a better load current THD than the conventional model for predictive control. For comparison, similar tests are performed on both 2-level and conventional 3-level inverters. Although the current load quality of the asymmetrical inverter is not as good as the traditional 3-level inverter, it is much better than the 2-level inverter. In addition, it has the benefits of significantly reducing overall costs, simpler hardware system design, and faster predictive processing than the conventional 3-level inverters. Therefore, this asymmetric inverter has advantages for an application with the required output characteristics like the conventional 3-level inverter and with lower cost.