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The increasing population and improved human quality of life bring new challenges to the aircraft industry in terms of increased greenhouse gas emissions as a result of increased air travel. To bring down the carbon footprint of the aviation sector, it is high time to advance toward electrifying air transportation. Consequently, electrification instigates the complex electric power systems (EPS), that adopt low-voltage dc architecture at higher currents to handle high power demands. As the aircraft EPS results in hybrid microgrid demands for a faster protection system for fault interruptions. Among the three main classifications of dc circuit breakers (DCCB), solid-state circuit breakers (SSCB) provide faster fault isolation. SSCBs can aid in achieving less weight and small form factor flight-weight electric components that are competent with high power requirements. This article proposes a modified O-Z-source DCCB (MOZSCB) topology containing a thyristor as the main fault interrupting switch and a coupled inductor helping the commutation of the thyristor. The proposed topology is engaged with fewer components owing to lessening the weight/volume of the aircraft system and can interrupt the fault within 400μs. Also, the proposed topology is designed to overcome the drawbacks of previously reported conventional O-Z-source DCCB, such as negative current flow through the load during reclosing and unwanted power flow while it's commissioning. The proposed topology also mitigates the issues of high current stress on the thyristor while reclosing. To validate the performance of the proposed MOZSCB, a laboratory prototype has been built with a system rating of 270V/10A.

In recent years, low-voltage direct current (LVDC) microgrids are becoming more attractive because they represent a solution to integrate renewable sources, storage, and electronic loads bringing some advantages in comparison with traditional AC grids. However, the protection of such a network involves many challenges, especially in the case of LVDC microgrids with more than one feeder and multiple energy sources. Indeed, the traditional protection breakers used for an AC grid cannot isolate the faults and protect the components of a DC grid, while the use of solid-state circuit breakers increases energy losses. This paper deals with the analysis and design of the protection schemes for LVDC microgrids through the combination of mechanical circuit breakers and hybrid circuit breakers. This solution has the advantage of energy loss reduction but introduces further issues due to the slow transition times of the mechanical circuit breakers. Thus, a completely decentralized control system capable of overcoming the fast fault-clearing time, cost-effectiveness, and selectivity issues is designed to protect from pole-to-pole faults. The proposed control strategy is compared with a centralized protection scheme available in the literature through numerical simulation. The two algorithms show similar performances, with a mean voltage dip duration of less than 30 ms and a maximum voltage dip duration of about 100 ms in the most severe fault condition, but the proposed solution is more reliable and flexible since it does not depend on the communication system.