An Ultralow-Loss Fault-Current-Limiting Z-Source LVDC Circuit Breaker Using Cryogenic Power Electronics

Room-temperature power electronics based dc circuit breakers and fault current limiters face two major challenges: high conduction loss and time-delayed response. This letter presents a novel circuitry, for the first time (based on literature studies), to combine cryogenic power electronics (CPE), together with the superconducting Z-source dc circuit breaker technology. The design, fabrication, and tests of the new device were carried out, and three advantages were proved. First, the actual overall system loss (including cryogenic issues) reduced by 62.1% in the 2 kW case study. Second, the no-delay automatic fault current limiting technology provided a sudden protective resistor ∼0.1 Ω to suppress the fault below 200 A, and meanwhile stabilized the bus voltage. Third, the CPE-based breaker achieved both the active device isolation and passive fault isolation within 60 μs.