Managing Branch Currents in Switches

Within a direct current hybrid circuit breaker (DC HCB), a commutation unit (CU) is provided in a semiconductor switch path in series with a semiconductor switch to facilitate opening the DC HCB. The semiconductor switch path is connected in parallel with a switch path that includes a mechanical switch. The CU is a controlled voltage source which applies a reverse biased voltage on the semi-conductor switch path. The CU causes the current through the mechanical switch to ramp down while the current through the semiconductor switch ramps up to a supply current. The CU maintains the current through the mechanical switch to remain at a zero vale by compensating for the voltage drop across the semi-conductor switch and the self-inductance of the semiconductor switch path. The mechanical switch can open without current and against no recovery voltage.