A Novel Railgun-Based Actuation System for Ultrafast DC Circuit Breakers in EV Fast-Charging Applications

This paper presents a novel ultrafast DC circuit breaker concept based on a railgun actuator, designed for ultrafast charging stations operating at 800 V and delivering up to 640 kW. The proposed breaker achieves contact opening speeds exceeding 190 m/s, enabling fault current interruption within 200 mu s and limiting the peak fault current to 2200 A. This performance significantly reduces breaker stress compared with conventional mechanical solutions. System-level simulations demonstrate a dramatic reduction in energy dissipation during faults-from 11,000 J with a conventional fast breaker to just 250 J using the proposed design. A 3D finite element method model of the railgun actuator confirms the feasibility of achieving a 15 mm stroke in 150 mu s. The evolution of current density and magnetic field is analyzed, highlighting the influence of skin and velocity skin effects. Results confirm that the proposed solution acts both as a circuit breaker and a fault current limiter, enhancing safety, reliability, and durability in high-power DC systems.