A Thyristor-Based Fault Current Bypass Solid-State Circuit Breaker for DC Microgrid Applications

Thyristor-based solid-state circuit breaker (SSCB) has high efficiency as a protection device for DC microgrid distribution. However, the passive turn-off and microsecond-level turn-off time make thyristor-based SSCBs more suitable for high-inertia DC systems. Large inductance in DC systems extends the fault clearing time. This paper proposes a thyristor-based fault current bypass SSCB (TFCB-SSCB) for DC microgrids. The proposed topology, compared to conventional thyristor-based SSCBs, not only offers high efficiency but also achieves rapid isolation of the source and fault side, with the only additional cost being a switch with a low breakdown voltage. Initially, the superiority of the proposed topology is analyzed in comparison to the prior-art thyristor-based topology. Next, the operating principles and key design considerations are presented for the proposed topology. Finally, the effectiveness of the proposed topology is verified through simulation results on an 800 V/ 165 A TFCB-SSCB model and experimental results on a 100 V/68 A TFCB-SSCB prototype. The fault isolation time of the proposed topology is five times faster than that of the traditional topology in simulations and twice as fast in experiments.