Bipolar hybrid circuit breaker for low-voltage DC circuits

A DC circuit breaker method comprising:

• providing a DC circuit breaker circuit having a first mechanical switch in series with a second mechanical switch, a first capacitor in parallel with the first mechanical switch, a second capacitor in parallel with the second mechanical switch, a first diode coupled between a first terminal of the first mechanical switch and a second terminal of the second mechanical switch, and a second diode coupled between a first terminal of the second mechanical switch and a second terminal of the first mechanical switch;
• connecting the DC circuit breaker circuit to a power line, wherein a sending end of a power line is connected to the first terminal of the first mechanical switch and the first terminal of the second mechanical switch, wherein a receiving end of the power line is connected to the second terminal of the first mechanical switch and the second terminal of the second mechanical switch;
• during an initial stage of operation of the DC circuit breaker circuit, closing the first and second mechanical switches and turning off the first and second diodes;
• activating a second stage of operation by opening the second mechanical switch in response to a fault condition on the power line, wherein current is rerouted through the second capacitor, wherein a first RLC circuit is formed comprising a power line resistance and inductance and the second capacitor until voltage across the second capacitor exceeds a source voltage, wherein the first diode turns on when the voltage across the second capacitor exceeds the source voltage, wherein the first RLC circuit generates an underdamped oscillation in the current causing the current to decay;
• activating a third stage of operation by forming a first RL circuit in response to load current flowing through the first diode while the first mechanical switch remains closed, wherein the first RL circuit comprises power line resistance and inductance;
• activating a fourth stage of operation by opening the first mechanical switch in response to the fault condition on the power line, wherein current is rerouted through the first capacitor, wherein a second RLC circuit is formed comprising a power line resistance and inductance and the first capacitor until voltage across the first capacitor exceeds the source voltage, wherein the second diode turns on when the voltage across the first capacitor exceeds the source voltage;
• and
• activating a fifth stage of operation by forming a second RL circuit by load current flowing through the first and second diodes, wherein the second RL circuit comprises power line resistance and inductance, wherein current decays in the fifth stage and the current crosses zero;
• and
• activating a sixth stage of operation by turning off the first and second diodes after the current crosses zero, wherein a third RLC is formed comprising the power line resistance, inductance, and the first and second capacitors, wherein voltages at the first and second capacitors decay in an underdamped manner;
• wherein opening of the first and second mechanical switches and turning off of the first and second diodes act to reverse a direction of a current flow and clear a current fault,
• wherein the DC circuit breaker system is equipped with a surge arrestor at its input and a freewheeling diode at its output.