Active Power Decoupling by Closed-Loop Control of Power Oscillations for a Bidirectional Single-Phase DC-AC Converter

A control strategy for the active power decoupling in a single-phase full-bridge-based bidirectional dc-ac converter is proposed in this work. An ac-side auxiliary-circuit three-leg topology is used for the implementation. The proposal makes use of the instantaneous power theory for three-phase systems, applied to single-phase systems. A closed-loop control in the power domain is implemented, by matching the instantaneous power oscillations in the main circuit of the converter connected to the grid, with the instantaneous power oscillations in the auxiliary circuit. The control loop does not employ the measurement of the voltage or current on the dc-bus, nor the voltage on the auxiliary-circuit capacitor. Not requiring a calculation for the voltage reference on the auxiliary-circuit capacitor depending on the circuit parameters allows to eliminate the second harmonic power oscillations on the dc-bus even in the presence of parameteric uncertainty. Experimental and simulation results are presented to demonstrate the validity and effectiveness of the proposal.