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The DC circuit breaker is essential for supplying stable DC power with the advent of DC transmission/distribution and sensitive loads. Compared with mechanical circuit breakers, which must interrupt a very large fault current due to their slow breaking capability, a solid-state circuit breaker (SSCB) can quickly break a fault current almost within 1 [ms]. Thus, it can reduce the damage of an accident a lot more than mechanical circuit breakers. However, previous DC SSCBs cannot perform the operating duty, and are not economical because many SCR are required. Therefore, this paper proposes a new DC SSCB suitable for DC grids. It has a low semiconductor conduction loss, quick reclosing and rebreaking capabilities. As a result, it can perform the operating duties of reclosing and rebreaking. The proposed DC SSCB is designed and implemented so that it is suitable for home dc distribution at a rated power of 5 [kW] and a voltage of 380 [V]. The operating characteristics are confirmed by simulation and experimental results. In addition, this paper suggests design guidelines so that it can be applied to other DC grids. It is anticipated that the proposed DC SSCB may be utilized to design and realize many DC grid systems.

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These days, the widespread use of sensitive loads and distributed generators makes the solid-state circuit breaker (SSCB) an essential component in power circuits to achieve a high power quality for AC Grids. In traditional AC SSCB using SCRs, some auxiliary mechanical devices are required to make the reclosing operation possible before fault recovery. However, the proposed AC SSCB can break quickly and then be reclosed without auxiliary mechanical devices even during the short-circuit fault. Moreover, its fault current breaking time is short and its SSCB reclosing operation is fast. This results in a reduction of the economic losses due to fault currents and power outages. Through simulations and experiments on short-circuit faults, the performance characteristics of the proposed AC SSCB are verified. A design guideline is also suggested to apply the proposed AC SSCB to various AC grids.

There is no zero crossing of the current in DC power circuits. Thus unless you cut off the short-circuit current quickly, the electrical fire caused by electric arc or spark can occur. And after the initial fault breaking operation the long-duration sustained interruption without fault recovery may cause a lot of serious economic losses. Therefore this paper proposes a new DC SSCB that has quick reclosing and rebreaking capabilities, and thus can perform the operating duties of reclosing and rebreaking required by the industrial standards and regulations. The proposed DC SSCB can perform rapid breaking, thus the material costs of power facilities can be reduced as the rapid breaking of DC SSCB enables selecting lower specification devices and minimizing auxiliary SCR. Also it can perform the operating duty of reclosing and rebreaking even in the state that short circuit lasts on load side. The operating characteristics of the proposed SSCB are verified by simulations and experiments on short circuit fault.Index Terms-DC circuit breaker, DC SSCB, solid state circuit breaker, operating duty.