Model Predictive Control with Switching Frequency Minimization for Modified Packed U-cell Inverter

Abstract

In this paper, a finite control set model predictive control (FCS-MPC) for single-phase cascaded modified packed U-cell (MPUC) inverter is presented. The considered multilevel inverter (MLI) topology requires less number of switches and produces more levels in the output waveform compared to the conventional and recent ones. Two control objectives are achieved in the proposed control algorithm, reference current tracking and switching frequency minimization. The proposed FCS-MPC considers only the effective different vectors of the MPUC with eliminating the redundant states of the converter to reduce the computational effort of the algorithm. By minimizing a user-defined cost function, the developed FCS-MPC algorithm achieves low mean absolute reference tracking error of the grid current, high inverter voltage quality and low average switching frequency of the switches. The trade-off between the average switching frequency and the tracking performance with the voltage quality is studied to determine the suitable range of the weighting factor λn for the proposed system. Simulation results are presented using MATLAB/Simulink to verify the effectiveness of the control system.