A novel permanent magnet variable inductor (PMVI) is proposed for fault-current limiting applications. It is designed to fill the need in hybrid DC circuit breakers (DCCBs) to have low insertion inductance under normal operating conditions, but high inductance under fault conditions to slow down fault current di/dt. Below a designable ‘trip’ current the magnetic core the device is driven into saturation by permanent magnets. Under a fault condition, the flux induced by the fault current flowing in the inductor winding drives the core out of the saturation region, creating a large increase of inductance. A PMVI was designed and built targeting 600V/20A with 50μH inductance at the nominal operating point. This PMVI device achieved 300% peak inductance change during the fault condition
