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.