MEDIUM VOLTAGE DC SOLID STATE CIRCUIT BREAKER BENCH TEST

Abstract

Next generation fleets will rely on medium-voltage direct-current (MVDC) electric power distribution systems utilizing high power density and high-efficiency components. One key gap to make such MVDC systems feasible is a super-fast, high-efficiency, and high power density protection device. The U.S. Navy has previously developed a 1 kV, 1 kA solid state circuit breaker (SSCB). A new 2 kV, 1.2 kA SSCB has been designed by NPS with collaborating partners that has quadrupled power density. This innovative insulated gate bipolar transistor (IGBT)-based SSCB consists of anti-series IGBT modules, a parallel resistor-capacitor (RC) branch, and an electronically triggered metal-oxide varistor (MOV) branch. The novel electronically controlled MOV is comprised of a MOV in series with a silicon controlled rectifier (SCR) passively triggered during the IGBT turn-off process, improving the trade-off between the leakage current and clamping voltage. The use of a lower IGBT gate voltage allows the elimination of current limiting inductors, increasing the SSCB power density. This thesis focuses on the switching and thermal tests necessary to validate the implemented concepts, and the data will be used for down-selecting technical directions, improving the SSCB performance. The results show that the SSCB is sufficient to interrupt most faults while containing peak current and voltage within design parameters and the efficiency target can be met with comfortable thermal margins.