An Improved Discontinuous Space Vector Modulation for a Three-Phase Z-Source Inverter With a Modified Reference

In this article, a new control strategy, based on the improved discontinuous space vector modulation is proposed to control a three-phase $Z$ -source inverter. The proposed control strategy aims to improve the $Z$ -source performance by extending the modulation index range, maximizing the voltage gain, reducing the voltage stress (the dc-link voltage, and capacitors’ voltage), and reducing the inductance current ripple, which improves the efficiency and reduces the inductors and capacitors’ value requirements of the $Z$ -source impedance network and thus reduces the cost and the size of the inverter. This control strategy is performed by modifying the expression of the voltage reference in order to have a reference voltage magnitude that has a hexagonal shape in the space vector (alpha-beta plane). Simulation on the MATLAB/SIMULINK environment using PLECS software is performed to highlight the advantages of the proposed control strategy and compare it with the existing improved discontinuous space vector modulation. In addition, a prototype of a $Z$ -source supplying a three-phase resistive load was constructed to validate the simulation results experimentally. The main advantages of the proposed control strategy compared to the improved discontinuous space vector modulation are: 1) the improved quality of the output voltage signal by reducing the total harmonics distortion (THD); 2) the high efficiency by reducing conduction and switching power losses; 3) the extended range of the modulation index; 4) the high voltage gain; 5) the low voltage stress; 6) the reduced inductance current ripple; and 7) the low shoot-through current for the $Z$ -source network.