Direct model predictive control with an extended prediction horizon for quasi-Z-source inverters

Abstract

This paper presents a direct model predictive control (MPC) with an extended prediction horizon for the quasi-Z-source inverter (qZSI). The proposed MPC controls both sides of the qZSI based on the inductor current of the qZS network and the output current of the ac side. In order to improve the system performance, the MPC with extended prediction horizon is used. However, increasing the prediction horizon results in a huge increase in the computational burden which prevents the implementation of the MPC in real time. To solve this problem, two techniques are utilized, namely a branch-and-bound scheme and move blocking strategy. In this work, the discrete-time model of the qZSI is derived that accurately captures all operating modes and states. Then, the steady-state and transient operations of the qZSI with the proposed MPC are experimentally examined. The results confirm that by extending the prediction horizon, the qZSI behavior is significantly improved.