The Constant Power Transmission Control for Suppressing DC-Link Voltage Ripple Effect of Single-Phase AC–DC–AC Converter

The dual active bridge (DAB) converter achieves relatively high efficiency and high power density. Therefore, it is widely used in ac–dc–ac converters to provide electrical isolation between the input and output. However, the single-phase converter inherently exhibits significant low-frequency voltage ripple in the DAB topology. Traditional control strategies focus on reducing voltage ripple and optimizing the capacitor size by transferring fluctuating power through the DAB converter. This method leads to higher magnetic component and switch currents, as well as a larger transformer size. To suppress these effects, this article proposes a constant power transmission (CPT) control for the DAB converter. The proposed CPT control dynamically adjusts the modulation width of each operating cycle by tracking the input–output voltage fluctuations in real-time through the control variables. This ensures constant power transfer in the DAB converter. Compared to traditional methods, the proposed control strategy reduces both the RMS and peak-to-peak values of the inductor current, thereby reducing the size of the converter and improving system efficiency. Simulation and experimental results confirm that the CPT control effectively reduces the peak-to-peak and RMS values of the inductor current by 40.7% and 18.8%, respectively, reduces the transformer size by 21.4%, and increases the efficiency by 1.1%.