A Г-Source Circuit Breaker for DC Microgrid Protection

In this article, a novel Γ-source circuit breaker (CB) that can offer automatic fault isolation with no reflected fault current in the feeding source is proposed for the protection of dc microgrids. Compared with conventional Z-source CBs, this topology utilizes fewer elements through the magnetic coupling, thus allowing a considerably reduced volume and weight. To accurately quantify the breaker elements, detailed modeling over both short-circuit and overload faults is carried out. The derived equations are significantly valuable for guiding the implementation of the novel breaker. A soft-starting circuit is also introduced to limit the capacitor charging current when reenergizing the breaker. In addition, a bidirectional Γ-source CB extended from the unidirectional topology with the same impedance network is discussed. If required, a crowbar-type switch, which allows the breaker to be manually tripped, can be conveniently integrated into the Γ-source CB. This manual tripping switch is useful for clearing steady-state overload faults. Moreover, experimental waveforms of fault-clearing and manual tripping operations are included to validate the effectiveness of the novel CB.