Open Transistors Fault-Tolerant Schemes of Three-Phase Dual Active Bridge DC-DC Converters

This work proposes fault-tolerant schemes for open-transistor faults applied to three-phase dual active bridge converters (TPDABC), using different transformers: star-star, delta-delta, and delta-star. The proposal consists of operating the TPDABC as a single-phase dual active bridge converter, modifying the modulation strategy. This strategy avoids the need for additional components, which allows the converter to continue operating after an event of open transistor failure. The expressions of the average power when the converter operates in the fault-tolerant modes are determined. The analysis determines that the maximum power that can be transferred using the transformer delta-star is larger than the power obtained for star-star and delta-delta connections. Simulation results allow the proposed schemes to be validated.