A Simple and Robust Solid-State Circuit Breaker for Low Voltage DC Applications

The demand for solid-state circuit breakers (SSCBs) in modern DC power systems is growing because of their fast switching speed, high efficiency, and reliable fault protection. The existing DC-SSCBs have limitations such as high conduction losses, bulk weight and size, need for auxiliary power supply, high fault currents, limited fault ramp rates, and susceptibility to parasitic inductance and resistance. These issues are very crucial for the development of an effective SSCB, especially for low-voltage DC (LVDC) applications. This paper proposes a novel SSCB topology that ensures automatic fault response with a minimal number of components without any auxiliary power supply. The proposed design utilizes a silicon controlled rectifier (SCR) thyristor as the main switch, which is turned off by a MOSFET during a fault condition. At fault condition, the gate-to-source voltage of the MOSFET exceeds the threshold voltage and the MOSFET creates an alternate low-impedance path for the anode current of the SCR. As a result, the SCR loses its holding current, causing it to turn OFF. The proposed circuit exhibits less sensitivity to parasitic inductance and resistance, effective low-pass filtering, and the ability to detect slow-arising faults. These advantages make the proposed SSCB suitable for LVDC applications, offering a sensible way to enhance the protection of the DC system.