Novel Semiconductor Power Switch for LVDC Circuit Breakers

Abstract:
In future DC microgrids, as in the old AC world, protective devices will be needed to protect against fault current like overcurrent and short-circuits. Hybrid switchgear, combining semiconductor power switches and mechanical switches, is a suitable technical approach, primarily regarding the suppression of switching arcs. In a hierarchic topology like a DC microgrid, selectivity must be ensured. Errors that occur should be dealt with as fast and as close to the site as possible. To face these challenges, a novel 2-pole semiconductor power switch is introduced. This so-called inverse thyristor is fabricated in a 4H-SiC JFET technology and its intrinsic blocking mechanism is based on fundamental solid-state physics. Investigations to demonstrate the suitability of the inverse thyristor for hybrid switchgear for DC are carried out at up to 800 V DC protecting a resistive inductive load (τ = 1.45 ms). The investigations reveal that the inverse thyristor detects and switches of fault current events << 1 mus (DeltaiL/Deltat800 V = 2.5 A/mus).