Solid state circuit breaker
A solid state circuit breaker has both solid state electronics and a physical switch. The solid state circuit breaker facilitates power measuring for end loads connected to a panel board circuit, e.g. receptacles, lighting, etc., over current protection, and disconnection all within one device. The solid state circuit breaker can be used at 100% of its rated capacity as opposed to 80% code-mandated limitation for thermal magnetic circuit breakers. The solid state circuit breaker also can provide power/current data (real-time) without the need of an additional device. The solid state circuit breaker further facilitates electronic, i.e. remote, opening, closing, and current limiting for demand response or load shedding.
1. A solid state circuit breaker including a first terminal to receive an AC voltage and a second terminal to output the AC voltage, the solid state circuit breaker comprising:
a current limiting circuit coupled to the first terminal;
a coupled transistor pair coupled between the first terminal and the second terminal;
a driver circuit coupled to the transistor pair;
a sensing circuit coupled to the first terminal, the second terminal, and the driver circuit, wherein the sensing circuit is configured to sense a first voltage characteristic at the first terminal, to sense a second voltage characteristic at the second terminal, and to supply the first voltage characteristic and the second voltage characteristic to the driver circuit, and further wherein the driver circuit is configured to turn OFF the transistor pair in response to first voltage characteristic being outside a first acceptable range or the second voltage characteristic being outside a second acceptable range; and
a controller circuit coupled to the first terminal, the second terminal, and the current limiting circuit, wherein the controller circuit is configured to determine a voltage difference between an input voltage at the first terminal and an output voltage at the second terminal, and in response to the voltage difference being outside a third acceptable range generate a trip signal sent to the current limiting circuit, and further wherein the current limiting circuit shunts current from the sensing circuit in response to receiving the trip signal thereby changing the first voltage characteristic to be outside the first acceptable range such that the driver circuit turns OFF the transistor pair.
2. The solid state circuit breaker of claim 1 , wherein the controller circuit, the current limiting circuit, the sensing circuit, and the driver circuit provide a first mechanism for turning OFF the transistor pair in response to a fault condition.
3. The solid state circuit breaker of claim 2 , wherein the sensing circuit and the driver circuit provide a second mechanism independent of the current limiting circuit and the controller circuit for turning OFF the transistor pair in response to the fault condition.
4. The solid state circuit breaker of claim 3 , wherein the first mechanism and the second mechanism provide redundancy for turning OFF the transistor pair in response to the fault condition.
5. The solid state circuit breaker of claim 2 , wherein the sensing circuit and the driver circuit provide a second mechanism dependent of the current limiting circuit and the controller circuit for turning OFF the transistor pair in response to the fault condition.
6. The solid state circuit breaker of claim 1 , wherein the current limiting circuit comprises a triac controlled by the trip signal.
7. The solid state circuit breaker of claim 1 , wherein the sensing circuit comprises a first comparator coupled to the first terminal and configured to output a first voltage difference corresponding to the first voltage characteristic, and a second comparator coupled to the second terminal and configured to output a second voltage difference corresponding to the second voltage characteristic.
8. The solid state circuit breaker of claim 1 , wherein the controller circuit is further configured to receive as input a remote control signal for turning OFF the solid state circuit breaker, and further wherein the controller circuit is configured to generate the trip signal in response to the remote control signal.
9. The solid state circuit breaker of claim 1 , wherein a first transistor of the transistor pair is configured to enable current flow from the first terminal to the second terminal during a positive half-cycle of the AC voltage, and wherein a second transistor of the transistor pair is configured to enable current flow from the first terminal to the second terminal during a negative half-cycle of the AC voltage.
10. The solid state circuit breaker of claim 1 , wherein the driver circuit is configured to turn ON the transistor pair when a fault condition that led to the generation of the trip signal is absent.
11. The solid state circuit breaker of claim 1 , wherein the controller circuit is configured to determine a fault condition based at least in part on the voltage difference between the input voltage at the first terminal and the output voltage at the second terminal.
12. The solid state circuit breaker of claim 1 , wherein the sensing circuit comprises one or more of:
circuitry comprising one or more of: transistors, operational amplifiers, resistors, inductors, and capacitors, for sensing current conditions; and
circuitry for sensing power conditions.
13. The solid state circuit breaker of claim 1 , wherein a first transistor of the transistor pair is turned ON during a positive half-cycle of the AC voltage in response to the first voltage characteristic being within the first acceptable range, and wherein a second transistor of the transistor pair is turned ON during a negative half-cycle of the AC voltage in response to the second voltage characteristic being within the second acceptable range.
14. A method for operating a solid state circuit breaker including a first terminal to receive an AC voltage and a second terminal to output the AC voltage, the method comprising:
sensing, by a sensing circuit, a first voltage characteristic at the first terminal, the sensing circuit being coupled to the first terminal, the second terminal, and a driver circuit, the driver circuit being coupled to a transistor pair, and the transistor pair being coupled between the first terminal and the second terminal;
sensing, by the sensing circuit, a second voltage characteristic at the second terminal;
supplying, by the sensing circuit, the first voltage characteristic and the second voltage characteristic to the driver circuit;
turning OFF, by the driver circuit, the transistor pair in response to the first voltage characteristic being outside a first acceptable range or the second voltage characteristic being outside a second acceptable range;
determining, by a controller circuit, a voltage difference between an input voltage at the first terminal and an output voltage at the second terminal, the controller circuit being coupled to the first terminal, the second terminal, and a current limiting circuit, and the current limiting circuit being coupled to the first terminal;
in response to the voltage difference being outside a third acceptable range, generating, by the controller circuit, a trip signal sent to the current limiting circuit; and
in response to receiving the trip signal, shunting, by the current limiting circuit, current from the sensing circuit thereby changing the first voltage characteristic to be outside the first acceptable range such that the transistor pair is turned OFF by the driver circuit.
15. The method of claim 14 , wherein, in response to a fault condition, a first mechanism for turning OFF the transistor pair is provided by the controller circuit, the current limiting circuit, the sensing circuit, and the driver circuit.
16. The method of claim 15 , wherein, in response to the fault condition, a second mechanism independent of the current limiting circuit and the controller circuit for turning OFF the transistor pair is provided by the sensing circuit and the driver circuit.
17. The method of claim 15 , wherein, in response to the fault condition, a second mechanism dependent of the current limiting circuit and the controller circuit for turning OFF the transistor pair is provided by the sensing circuit and the driver circuit.
18. The method of claim 14 further comprising:
outputting, by a first comparator coupled to the first terminal, a first voltage difference corresponding to the first voltage characteristic; and
outputting, by a second comparator coupled to the second terminal, a second voltage difference corresponding to the second voltage characteristic.
19. The method of claim 14 further comprising:
receiving as input, by the controller circuit, a remote control signal for turning OFF the solid state circuit breaker; and
generating, by the controller circuit, the trip signal in response to the remote control signal.
20. The method of claim 14 further comprising:
enabling, by a first transistor of the transistor pair, current flow from the first terminal to the second terminal during a positive half-cycle of the AC voltage; and
enabling, by a second transistor of the transistor pair, current flow from the first terminal to the second terminal during a negative half-cycle of the AC voltage.