Control of a complete digital-based component-minimized single-phase to three-phase AC/DC/AC converter

This paper proposes a new control strategy for a complete digital-based component minimized single- to three-phase AC/DC/AC power converter where it is possible by proper control to reduce the capacitor size in the DC-link. The power converter offers four quadrant operation including unity power factor and it uses only six transistors and six diodes. Control is done completely digitally with a high bandwidth input current controller and a lower bandwidth DC-link voltage controller. The modulation of the inverter compensates for the voltage variation in the DC-link. The proposed methods are validated through simulation and experimental work. It is concluded that the capacitor-size can be reduced significantly in a B4-inverter by the control method but a load dependent sub-harmonic current is injected into the grid.