Study on interruption characteristics of a current-injection-based soft turn-off solid-state DC circuit breaker

Driven by the “dual carbon” goals, the large-scale application of renewable power generation, DC distribution networks, and energy storage systems has increasingly highlighted the short-circuit protection challenges in low-voltage DC (LVDC) systems. LVDC faults are characterized by rapidly rising fault currents and the absence of natural current zero-crossings. In addition, conventional hard turn-off protection solutions suffer from obvious drawbacks, including high switching overvoltage and excessive electrical stress on power devices. To address the aforementioned problems, this paper proposes a soft-switching solid-state DC circuit breaker topology based on current injection, along with a protection strategy enabling seamless transition between soft and hard turn-off modes. A simulation model was built on the MATLAB/Simulink platform to validate the interruption characteristics under multiple working conditions, covering fault currents from 1 to 20 kA and system voltages from 1500 to 3000 V. Results show that under the 1500 V/10 kA condition, hard turn-off mode can interrupt the fault current within 7.6 μs, while soft turn-off mode achieves interruption in 36.6 μs. Within the fault current range of 1–20 kA, the fault breaking time remains between 35 and 37.1 μs. As the voltage increases from 1500 to 3000 V, the interruption time slightly rises from 36.6 to 38.4 μs, yet reliable fault isolation can be guaranteed under all test scenarios. The proposed topology offers high interruption reliability, low switching stress, and strong adaptability to various operating conditions, providing a high-speed, arc-free short-circuit protection solution for DC systems.