An ETO-based AC buck-type fault current limiter for use in the FREEDM project

This paper presents a new fault current limiter topology based on the emitter turn-off thyristor that is intended for the Future Renewable Electric Energy Delivery and Management (FREEDM) Project. This device is a hybrid device that combines the advantages of solid-state fault current limiters and traditional impedance injecting fault current limiters. Comparing existing devices, the proposed device offers low conduction losses during normal operation while limiting the peak fault current to two times the rated current. The limiting of the fault current is achieved by pulse width modulation and implementing an AC type buck converter. This buck type limiter achieves a full sinusoidal waveform compared to other limiters that switch on and off at a preset value. The ETO can switch the current within a few microseconds and block the fault current without breaking down.