Simplified Model Predictive Control for AC/DC Matrix Converters With Active Damping Function Under Unbalanced Grid Voltage

Abstract

Model predictive control (MPC) is applied to ac/dc matrix converters (MCs) to achieve fast dynamic response and simple implementation. However, the large number of calculations required for a conventional MPC (C-MPC) is an obstacle for its wide application. Moreover, active damping is used to mitigate LC resonance on the input side, which increases the computational burden of the C-MPC. The control performance of the C-MPC also deteriorates under unbalanced grid voltage conditions. To overcome these problems, this paper presents a simplified MPC (S-MPC) for ac/dc MCs to reduce the computational burden. A novel method is proposed to realize the active damping function, which involves a damping function in the S-MPC without increasing the calculation time. Thus, the system performance is easily improved by shortening the sampling period. Furthermore, the grid current reference is generated based on a quantitative analysis of the power flow to achieve constant output current, sinusoidal grid current, and an input power factor near unity under unbalanced grid voltage. Simulation and experiment were done to verify the effectiveness of the proposed control method.