Design considerations of series type hybrid circuit breaker (S-HCB)

The series-type direct current (DC) hybrid circuit breaker (S-HCB) concept was previously reported to offer better performance than solid-state circuit breakers (SSCB) and hybrid circuit breakers (HCB). S-HCB offers low conduction power loss like an HCB and mu s$\umu \text{s}$-scale interruption time, which is even faster than an SSCB. It uses a pulse transformer to isolate the lower-voltage high-inductance power electronic circuit from the high-voltage, low-inductance main power loop. This paper provides analysis of the impact of the S-HCB circuit components on the overall system performance and a scalable S-HCB design guide for different DC system voltage and current ratings. In addition, system energy flow analysis is performed in the time domain to provide an understanding of how energy is delivered, dissipated, and released throughout the entire fault interruption process. The S-HCB prototype was experimentally tested at 3 kV/30 A and 6 kV/150A with the results showing the interruption of the low fault current of 30 A and the high fault current of 150 A within 8 mu s$\umu \text{s}$ and maintaining the fault current at a near zero value for 300 mu s$\nobreakspace \umu \text{s}$ to enable an arcless opening of a series mechanical switch. The key design challenges of S-HCB at high voltage and high current ratings were discussed and possible solutions to mitigate those challenges were introduced. Design considerations of a series-type hybrid circuit breaker (S-HCB) offering ultralow power loss and microsecond scale fault interruption were discussed. System level design equations were provided as a guide for S-HCB circuit component selection for multiple MVDC circuit breaker voltage and current ratings. S-HCB system energy flow analysis is performed in time domain to provide an understanding of the full energy cycle and conservation in normal operation and during the fault interruption process.image