Air-Core Coupled Inductor-Based Modular Solid-State Circuit Breaker With Reduced Components for DC Buildings

Abstract

Traditional residential and commercial buildings can be decarbonized by adopting direct current (dc) microgrids powered by renewable energy sources. With the challenges of dc systems and increasing power consumption, dc distribution systems of the buildings require modular and fast protective dc circuit breakers (DCCBs) against fault events. A few modular thyristor-based solid-state circuit breakers (SSCBs) are presented in the literature for high-current applications. However, each proposed module requires a commutation circuit and a current sensor. This article proposes a novel single-branch SSCB (SB-SSCB) that uses air-core coupled coils to commutate an SCR in the main conduction path. The modularity is achieved by extending the SB-SSCB to the two-branch bidirectional SSCB (TB-SSCB) design to handle high currents. In this design, the two primary paths run parallel and share current, equipping three winding air-core coupled coils. The proposed TB-SSCB topology greatly reduces the component count because only one commutation circuit is required for fault current interruption in both branches. Air-core coils mitigate the necessity of over-dimensioning the core material to prevent saturation at higher current levels, hence decreasing the weight of the system. The proposed SB-SSCB and TB-SSCB are described in detail, including their operating modes. Then, a detailed approach for selecting and designing the components is provided. Later, the proposed topologies are compared to recent thyristor-based DCCBs. The proposed SB-SSCB and TB-SSCB are experimentally validated by developing a laboratory prototype for the standardized voltage level of 350 V dc given by the IEC 60364 and NPR 9090 for houses, offices, and commercial buildings, and at a nominal current rating of 10 A.