PSAM and TM Based Fault Tolerant Scheme for Open Switch Faults in Dual Active Bridge Converters

Dual active bridges (DABs) are widely utilized in solid-state transformers (SSTs) and energy storage systems. The reliability of an isolated DAB converter is critically dependent on its performance under various fault conditions, with open switch faults (OSFs) being a predominant issue. This study introduces an innovative fault-tolerant scheme for DAB DC-DC converters to address OSFs on both the primary and secondary sides. The proposed method integrates phase shift angle modulation (PSAM) along with topology modifications (TM). Initially, the operational behavior of the DAB under normal conditions, as well as under primary and secondary switch OSFs, is analyzed. Based on this analysis, PSAM, and TM techniques is proposed to address OSFs, focusing particularly on faults occurring in switches S1 and S5. The proposed fault-tolerant scheme is capable of transmitting 75% of the nominal power during primary side OSFs and approximately 98% during secondary side OSFs, thereby ensuring continued safe operation. The effectiveness and accuracy of the proposed scheme for managing OSFs are validated through MATLAB simulations.