A Δ-Source DC Circuit Breaker for Microgrid Protection

Conventional Z-source type circuit breakers exhibit inherent drawbacks such as such as non-common ground, significant source-side fault currents, and a narrow autonomous breaking range causing misoperation. To address these issues, this paper proposes a novel bidirectional △-source circuit breaker topology. The △-source circuit breaker utilizes a three winding coupled inductor, which can generate a higher coupled current at the instant of a short-circuit, thereby achieving a faster turn-off speed. Moreover, △-source circuit breaker has a special topology structure that can flexibly reconfigure the circuit breaker structure through the opening of any winding, enabling more adaptable adjustment of its autonomous breaking range. Additionally, this paper analyzes the operational principle of the circuit breaker, develops a stage-by-stage model, and establishes a model for defining its autonomous breaking range. Finally, through theoretical analysis, comparative studies, and experimental validation, this paper verifies the △-source circuit breaker's ability to achieve microsecond-level fault interruption and bidirectional breaking performance, and demonstrates the accuracy of the model for its autonomous breaking range.