Current Discrepancy Mitigation of Input-Parallel Output-Parallel Dual-Active-Bridge Converters Using Coupled Inductors

Due to the advantages such as bidirectional power flow, soft switching and high efficiency, input-parallel output-parallel dual-active-bridge converters are suitable for high-current application such as low-voltage dc distribution so as to increase the current capacity. However, in practical applications, parameter mismatches cause current imbalances among parallel modules, leading to imbalanced loss dissipation, and thus, the system performance is compromised. In this regard, this article proposes an automatic current-sharing method for input-parallel output-parallel dual-active-bridge converters using coupled inductors without any current sensors or digital algorithms to mitigate the issue and, thus, improve system reliability, at the minimum cost. The current-sharing method is analyzed in detail quantitatively and design consideration of the coupled inductor is presented to show its easy implementation. Additionally, module shading at light loads can be achieved using a passive selector with ease smoothly, guaranteeing high efficiencies all over the loading range. Simulation and experimental results verified that the current sharing is accomplished under both steady and dynamic operations.