Instant current limiter using a magnetic switching for DC circuit — Basic principles and circuit analysis

In this paper, instant current limiter using a magnetic switching for DC power system is proposed. In DC power system, it is very difficult to cut off the fault current because it has no zero-crossing. This paper proposes an instant current limiter to reduce the DC current instantaneously by using a magnetic switching circuit, which can be utilized as a DC FCL(fault current limiter) for DC circuit breaker. The existing cut-off approach for DC system uses dI/dt to decide whether the fault occurs or not in order to achieve fast cut-off approach before the fault current is increased. But fast fault decision using dI/dt has a relatively large uncertainty so it would cause malfunctions. With the aid of the proposed FCL, it is possible to achieve a safe cut-off of the fault current after the fault current is increased enough. We can ensure an enough time to decide the fault occurrence and reduce a cut-off capacity and increase a safety to cut off the fault current. The suggested system can also be utilized to AC current limiter for power systems with a large range of application in the future.