Combinative Voltage Vector-Based Model Predictive Control for Performance Improvement of Quasi Z-Source Inverter

Model predictive control (MPC) has been commonly recognized as a promising control strategy for the quasi Z-source inverter (qZSI). However, large control error is regarded as an innate drawback of MPC due to only one voltage vector applied per control cycle. In this paper, an improved MPC, namely combinative voltage vectors based MPC, is proposed for the qZSI to reduce the control error and improve steady-state performance. Two different voltage vectors are applied in one control cycle, so that the cost function value can be reduced. The errors of the inductor current, the capacitor voltage, and the output current of the qZSI included in the cost function can be decreased greatly. Furthermore, the performance investigation of the proposed method indicates that the two selected voltage vectors consisting of a non-shoot-through vector and a shoot-through vector is of help in shorting the charge-discharge period of inductor. Thus, the inductor current ripple as well as the total harmonics distortion (THD) of the output current is greatly reduced. The experimental results show the validity and the advantages of the proposed method.