CONTROL OF DIRECT CURRENT CIRCUIT BREAKERS WITH SERIES SEMICONDUCTOR SWITCHES

Various examples are provided related to direct current circuit breakers and their control methods. In one example, among others, a hybrid direct current circuit breaker (DCCB) includes an ultrafast mechanical switch (UFMS) connected in series with a commutating switch (CS) or auxiliary circuit breaker (ACB); a main breaker (MB) including a series of η semiconductor switching stages in parallel with the UFMS and CS or ACB; and control circuitry that can turn off individual switching stages in a defined order in response to opening contacts of the UFMS. The switching stages can be turned off based upon a dielectric strength across the contacts as they open. In another example, a method includes opening contacts of an UFMS connected in series with a CS or ACB; and turning off individual switching stages of a series of η semiconductor switching stages connected across the UFMS and the CS or ACB.