Direct current hybrid circuit breaker with reverse biased voltage source

A direct current (DC) hybrid circuit breaker (HCB), comprising:

• an input;
• an output;
• a mechanical switch path comprising a mechanical switch, wherein the mechanical switch path is coupled between the input and the output;
• a semiconductor switch path comprising a semiconductor switch connected in series with a commutation unit configured to supply a reverse biased voltage source on the semiconductor switch path, wherein the semiconductor switch path is coupled between the input and the output in parallel to the mechanical switch path, wherein the commutation unit comprises:
• a capacitor;
• an input of the commutation unit, where the input of the commutation unit is coupled to a negative terminal of the capacitor;
• an output of the commutation unit;
• a first switch, where a first side of the first switch is coupled to a positive terminal of the capacitor;
• a second switch, where a first side of the second switch is coupled to a second side of the first switch and is coupled to the output of the commutation unit, and where a second side of the second switch is coupled to the input of the commutation unit and the negative terminal of the capacitor.

A direct current (DC) hybrid circuit breaker (HCB), comprising:

• an input;
• an output;
• a mechanical switch path comprising a mechanical switch, wherein the mechanical switch path is coupled between the input and the output;
• a semiconductor switch path comprising a semiconductor switch connected in series with a commutation unit configured to supply a reverse biased voltage source on the semiconductor switch path, wherein the semiconductor switch path is coupled between the input and the output in parallel to the mechanical switch path, wherein the commutation unit comprises:
• a capacitor;
• an input of the commutation unit;
• an output of the commutation unit;
• a first switch, where a first side of the first switch is coupled to a positive terminal of the capacitor;
• a second switch, where a first side of the second switch is coupled to a second side of the first switch and the output of the commutation unit, and where a second side of the second switch is coupled to a negative terminal of the capacitor;
• a third switch, where a first side of the third switch is coupled to the positive terminal of the capacitor and the first side of the first switch;
• a fourth switch, where a first side of the fourth switch is coupled to a second side of the third switch and the input of the commutation unit, and where a second side of the fourth switch is coupled to the negative terminal of the capacitor and the second side of the second switch.

A method of operating a direct current (DC) hybrid circuit breaker (HCB), the method comprising:

• detecting an over-current condition in a switch current across a closed mechanical switch in a mechanical switch path of the DC HCB;
• in response to detecting the over-current condition, closing a semiconductor switch and providing a reverse biased commutation voltage by a commutation unit, wherein the semiconductor switch and the commutation unit are connected in series across a semiconductor switch path of the DC HCB and the semiconductor switch path is coupled in parallel to the mechanical switch path;
• detecting that the switch current reaches a zero-current condition and responsively opening the mechanical switch;
• maintaining the zero-current condition in the switch current for a predetermined period of time;
• and
• after the predetermined period of time, opening the semiconductor switch and turning off the commutation unit.

A method of operating a direct current (DC) hybrid circuit breaker (HCB), the method comprising:

• detecting an over-current condition in a switch current across a closed mechanical switch in a mechanical switch path of the DC HCB;
• in response to detecting the over-current condition, closing a semiconductor switch and providing a reverse biased commutation voltage by a commutation unit, wherein the semiconductor switch and the commutation unit are connected in series across a semiconductor switch path of the DC HCB and the semiconductor switch path is coupled in parallel to the mechanical switch path;
• detecting that the switch current reaches a zero-current condition and responsively opening the mechanical switch;
• and
• maintaining the zero-current condition in the switch current for a predetermined period of time, wherein the commutation unit comprises a capacitor, a first switch, and a second switch, wherein the first switch is coupled between a positive terminal of the capacitor and a positive terminal of the commutation unit, the second switch is coupled between the positive terminal of the commutation unit and a negative terminal of the commutation unit, and a negative terminal of the capacitor is coupled to the negative terminal of the commutation unit.