Modified Modulated Model Predictive Control Strategy for a Grid-Connected Converter

This article proposes a modified modulated model predictive control (M3PC) for a grid-connected converter, which features enhanced steady-state and transient performance, low complexity, and capability of multiobjective optimization. The advantages of fast dynamics and inherent overmodulation capability of finite control set model predictive control are preserved while a constant switching-frequency and improved steady-state performance are achieved. High tracking error and distortion caused by the limitation of conventional modulated model predictive control (M2PC) optimization near the hexagonal limit of voltage vectors and the sector boundaries are addressed with the proposed M3PC scheme. Experimental results verify that reduced tracking errors and lower total-harmonic distortion in grid current are achieved by the proposed method compared to the conventional M2PC scheme. It is also confirmed that the capability of overmodulation operation in the proposed method enhances transient performance and dc-bus utilization.