A DC Bias Elimination Strategy for DAB Converter Based on Duty Cycle Redistribution

The dual active bridge (DAB) converter, characterized by its symmetrical architecture, ensures self-volt-second balance for stable operation. However, transients such as startup events, load switching, or adjustments to the reference voltage can rapidly alter the shift ratio, necessitating a swift response to power demands. This abrupt change in shift ratio induces fluctuations in the peak current of the series inductor and generates significant DC bias current over multiple switching cycles. Such currents may lead to magnetic saturation within the transformer or power inductor, posing a risk of system failure. A new approach has been suggested to get rid of the DC bias current in the series inductors of a DAB converter when using single-phase shift control. Unlike conventional strategies that require adjustments to the shift ratio for power transmission, this approach offers versatility across various operational modes. The efficacy of this strategy in reducing DC bias current has been empirically validated, underscoring its potential to enhance system reliability.