Design of a reduced component count single-phase to three-phase quasi-Z-source converter

This study proposes a cost-effective four-switch single-phase to three-phase converter with an improved space vector pulse width modulation method. This structure employs the quasi-Z-source (QZs) topology that can be utilised in induction motor drive applications. Compared with conventional four-switch structures, buck-boost operation is a unique property of this configuration. This four-switch QZs structure decreases the switching losses, load current total harmonic distortion and cost in comparison with traditional six-switch structures. Without using any extra filtering circuits, the applied modulation method can work well to reject the influence of DC-link voltage ripples on the converter voltage, which can be accomplished by either power supply or voltage variations in the four-switch structure. The closed-loop modulation strategy recognises via sensing any unbalanced voltage that occurs across two split capacitors, and by applying the changes in the vector´s activation interval time, the three-phase output voltage can be balanced. The simulation and experimental results of the suggested converter with the improved modulation method have demonstrated the converter´s performance and the potential of the structure to be further developed.