Hybrid circuit breaker using a transient commutation current injector circuit
A circuit breaker and method of operation. The circuit breaker includes a first current path including a mechanical switch, such as an ultrafast mechanical switch, and a second current path in parallel connection to the first current path, and including a current injector, such as a transient commutation current injection circuit, in series with bidirectional power electronic switch. A short circuit fault current from a mechanical switch path is communicated to the electronic path via a current injection, followed by interrupting the fault current. A pulse current is generated to the electronic switch in the second current path, and the mechanical switch is opened during the pulse current. The pulse current and the electronic switch reduce or eliminate arcing upon the opening the mechanical switch.
1 . A circuit breaker, comprising:
a first current path including a mechanical switch;
a second current path in parallel connection to the first current path, the second current path including a current injector in series with an electronic switch, wherein, upon activation during an overcurrent condition in the first current path, the current injector generates a pulse current to the electronic switch.
2 . The circuit breaker according to claim 1 , wherein the mechanical switch comprises an ultrafast mechanical switch.
3 . The circuit breaker according to claim 1 , wherein the first current path does not include any electronic switch in series with the mechanical switch.
4 . The circuit breaker according to claim 1 , further comprising a current sensor configured to detect the overcurrent condition.
5 . The circuit breaker according to claim 1 , wherein the mechanical switch opens when the current injector commutates a load current from the first current path to the second current path.
6 . The circuit breaker according to claim 1 , further comprising a varistor in parallel connection to the second current path, wherein the varistor activates upon the electronic switch turning off.
7 . The circuit breaker according to claim 1 , further comprising a varistor downstream of the current injector and in parallel connection to the electronic switch.
8 . The circuit breaker according to claim 1 , further comprising a control circuit in combination with the current injector, to activate the current injector upon the overcurrent condition in the first current path.
9 . The circuit breaker according to claim 8 , wherein upon activation the current injector generates a regulated pulse current to commutate a load current from the first current path to the second current path.
10 . The circuit breaker according to claim 8 , wherein the current injector comprises a power converter.
11 . The circuit breaker according to claim 10 , wherein the power converter comprises an auxiliary DC power supply in combination with a capacitor.
12 . The circuit breaker according to claim 1 , wherein the pulse current is substantially equal to the load current.
13 . The circuit breaker according to claim 1 , wherein the pulse current comprises a switch-mode pulse current.
14 . The circuit breaker according to claim 1 , wherein the load current of the first current path flows freely through the current injector upon a commutation from the first current path to the second current path.
15 . The circuit breaker according to claim 1 , wherein the current injector is configured to operate in a bang-bang current control mode to provide the pulse current.
16 . The circuit breaker according to claim 1 , wherein upon activation during the detected overcurrent condition in the first current path, the current injector generates a plurality of pulse currents to the electronic switch.
17 . A circuit breaker, comprising:
a first current path including a mechanical switch;
a second current path in parallel connection to the first current path, the second current path including a current injector in series with an electronic switch; and
a control circuit in combination with the current injector, the control circuit is configured to activate the current injector upon a detected overcurrent condition in the first current path, wherein upon activation during the detected overcurrent condition the current injector generates a switch-mode pulse current and the mechanical switch opens when the switch-mode pulse current of the current injector commutates a load current from the first current path to the second current path.
18 . The circuit breaker according to claim 17 , wherein the switch-mode pulse current matches the load current.
19 . The circuit breaker according to claim 17 , wherein the switch-mode pulse current is equal to the load current.
20 . The circuit breaker according to claim 17 , wherein the electronic switch is downstream of the current injector, and further comprising a varistor downstream of the current injector and in parallel connection to the electronic switch.