A Simple DC-Offset Eliminating Method of the Series-Inductance Current for the DAB DC-DC Converter

Based on the phase-shift modulation, the dual-active-bridge (DAB) dc-dc converter always features the natural self-volt-second balance performance even during the transient process. Besides, different phase-shift ratios usually result in different initial series-inductance currents. Therefore, when the phase-shift ratio is suddenly changed for dealing with the change of required transferred power, a dc offset in the series-inductance current will emerge. Especially for the high-power condition, this dc offset lasts for a long time because of the high-current value but low damping conduction resistor. Then, the magnetic saturation phenomenon may emerge in the transformer, resulting in the potential failure of the converter system. To address this issue, a simple dc-offset eliminating method is proposed for the DAB dc-dc converter. Different from most of the existing methods, the proposed one is independent from the phase-shift modulation method. Therefore, the proposed dc-offset eliminating method can be easily embedded in different phase-shift modulation methods, such as single-phase-shift, double-phase-shift, and triple-phase-shift methods. Finally, the experimental results are provided to verify the effectiveness of the proposed dc-offset eliminating method for the DAB dc-dc converter.

Automated summary

Based on phase-shift modulation, the DAB dc-dc converter exhibits self-volt-second balance and may experience a dc offset in series-inductance current when changing the phase-shift ratio suddenly. This can lead to magnetic saturation in the transformer and potential failure of the converter system. To address this issue, a simple dc-offset eliminating method independent of the phase-shift modulation method is proposed. Experimental results demonstrate the effectiveness of the proposed method for the DAB dc-dc converter.