Solid State Circuit Breaker

Abstract

The circuit breaker includes a current sensor having a normal sensor output and an overcurrent detection output, a solid state switch module configured to have a closed state that allows current to flow through the circuit breaker and an open state that interrupts current flow through the circuit breaker, a gate driver configured to control the solid state switch module having a desaturation function output, the gate driver configured to cause the solid state switch module to interrupt current flow through the circuit breaker when the desaturation function output changes to an on state, and an electronic trip circuit configured to output a trip signal to the gate driver when the normal sensor output reaches a first threshold level or the overcurrent detection output changes to the on state.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application is related to commonly assigned, concurrently filed U.S. patent application Ser. No. 16 / 775,985, entitled "SOLID STATE CIRCUIT INTERRUPTER," filed Jan. 29, 2020 (Attorney Docket No. 19-ETU-783-2).

[0002] FIELD OF THEINVENTION The disclosed concepts relate generally to circuit breakers and, more particularly, to solid-state circuit breakers. [Background technology]

[0003] For example, but not by way of limitation, circuit interrupters, such as circuit breakers, are typically used to protect electrical circuits from damage caused by an overcurrent condition, such as an overload condition, a short circuit, or another fault condition, such as an arcing or ground fault. Solid-state circuit breakers use solid-state components, e.g., semiconductor devices, to switch on and off the electrical current flowing from a power source to a load.

[0004] Solid-state circuit breakers offer faster tripping than conventional mechanical circuit breakers. However, these capabilities are not optimally utilized. Furthermore, solid-state circuit breakers pose different safety and integrity concerns than conventional mechanical circuit breakers. There is considerable room for improvement of solid-state circuit breakers. Summary of the Invention

[0005] According to one aspect of the disclosed concept, a circuit breaker configured to electrically connect between a power source and a load includes a current sensor configured to sense a current flowing through the circuit breaker, the current sensor having a normal sensor output proportional to the current flowing through the circuit breaker and an overcurrent detection (OCD) output that changes to an on state when the current flowing through the circuit breaker reaches a second threshold level; a solid state switch module configured to have a closed state that allows current to flow through the circuit breaker and an open state that interrupts the current flowing through the circuit breaker; and a gate driver configured to control the solid state switch module to interrupt the current flowing through the circuit breaker, the gate driver configured to interrupt the current flowing through the circuit breaker. a gate driver including a desaturation (DESAT) function output that changes to an ON state when current through the circuit breaker reaches a third threshold level, and configured to cause the solid-state switch module to interrupt current through the circuit breaker when the DESAT function output changes to the ON state; and an analog trip circuit configured to receive the normal sensor output and the OCD output and output a trip signal to the gate driver when the normal sensor output reaches the first threshold level or the OCD output changes to the ON state, the trip signal causing the gate driver to control the solid-state switch module to interrupt current through the circuit breaker.

[0006] According to one aspect of the disclosed concept, a circuit breaker configured to electrically connect between a power source and a load includes separable contacts configured to open to provide galvanic isolation between the power source and the load, an operating mechanism configured to open and close the separable contacts, a first position sensor configured to sense a position of the separable contacts, a solid-state switch module configured to have a closed state that allows current to flow through the circuit breaker and an open state that interrupts current flow through the circuit breaker, and an electronic trip unit configured to control the solid-state switch module to change between the open and closed states and to control the operating mechanism to open the separable contacts, the electronic trip unit being configured to control the solid-state switch module to change from the open state to the closed state when the separable contacts are in the closed position based on an output of the first position sensor.

[0007] According to one aspect of the disclosed concept, a solid-state switch assembly for use in a circuit breaker includes an input terminal, a first conductor, an output terminal, a second conductor, a solid-state switch module electrically connected to the input terminal using the first conductor and electrically connected to the output terminal using the second conductor and including at least one solid-state switch, a heat sink attached to the solid-state switch module, a current sensor configured to sense current flowing through the solid-state switch module, and a number of metal oxide varistors (MOVs).

[0008] According to one aspect of the disclosed concept, a circuit breaker includes a frame including a number of compartments, and a number of solid-state switch assemblies, each solid-state switch assembly disposed in a corresponding one of the compartments and including an input terminal, a first conductor, an output terminal, a second conductor, a solid-state switch module electrically connected to the input terminal using the first conductor and to the output terminal using the second conductor and including at least one solid-state switch, a heat sink, a current sensor configured to sense a current flowing through the solid, and a number of metal oxide varistors (MOVs).

[0009] According to one aspect of the disclosed concepts, a method of operating a circuit breaker having a solid-state switch module including a solid-state switch includes monitoring a characteristic of the solid-state switch, determining that the characteristic of the solid-state switch meets or exceeds a predetermined threshold, and providing an indication in response to determining that the characteristic of the solid-state switch meets or exceeds a predetermined threshold. [Brief description of the drawings]

[0010] A complete understanding of the concepts of the present disclosure can be gained from the following detailed description when read in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a schematic diagram of a circuit breaker according to an exemplary embodiment of the concepts of the present disclosure. [Diagram 2] FIG. 2 is a circuit diagram of a power supply in accordance with an exemplary embodiment of the disclosed concepts. [Figure 3A] FIG. 1 is a circuit diagram of an analog trip circuit in accordance with an exemplary embodiment of the disclosed concepts. [Figure 3B] FIG. 1 is a circuit diagram of an analog trip circuit in accordance with an exemplary embodiment of the disclosed concepts. [Figure 4A] FIG. 1 is a circuit diagram of a gate driver circuit according to an exemplary embodiment of the disclosed concepts. [Figure 4B] FIG. 1 is a circuit diagram of a gate driver circuit according to an exemplary embodiment of the disclosed concepts. [Figure 5A] FIG. 1 is a partial assembly view of a circuit breaker according to an exemplary embodiment of the disclosed concepts. [Figure 5B] FIG. 1 is a partial assembly view of a circuit breaker according to an exemplary embodiment of the disclosed concepts. [Figure 6A] FIG. 1 is a partial assembly view of a circuit breaker according to an exemplary embodiment of the disclosed concepts. [Figure 6B] FIG. 1 is a partial assembly view of a circuit breaker according to an exemplary embodiment of the disclosed concepts. [Figure 7] FIG. 1 illustrates a partially disassembled circuit breaker in accordance with an exemplary embodiment of the concepts of the present disclosure. [Figure 8]FIG. 2 is a partial interior side view of a circuit breaker according to an exemplary embodiment of the disclosed concepts. [Figure 9A] 1 is a diagram of a solid-state switch assembly according to an exemplary embodiment of the disclosed concepts; [Figure 9B] 1 is a diagram of a solid-state switch assembly according to an exemplary embodiment of the disclosed concepts; [Figure 9C] 1 is a diagram of a solid-state switch assembly according to an exemplary embodiment of the disclosed concepts; [Figure 10A] 1 is a diagram of a heat sink and solid state switch module according to an exemplary embodiment of the disclosed concepts; [Figure 10B] 1 is a diagram of a heat sink and solid state switch module according to an exemplary embodiment of the disclosed concepts; [Figure 10C] 1 is a diagram of a heat sink and solid state switch module according to an exemplary embodiment of the disclosed concepts; [Figure 10D] 1 is a diagram of a heat sink and solid state switch module according to an exemplary embodiment of the disclosed concepts; [Figure 11A] 1 is a diagram of a frame housing solid state switch assembly according to an exemplary embodiment of the disclosed concepts; [Figure 11B] 1 is a diagram of a frame housing solid state switch assembly according to an exemplary embodiment of the disclosed concepts; [Figure 12] 1 is a flow chart of a method of operating a circuit breaker in accordance with an exemplary embodiment of the disclosed concepts. BEST MODE FOR CARRYING OUT THEINVENTION

[0011] Directional phrases used in this specification, such as left, right, front, back, top, bottom, and variations thereof, refer to the orientation of the elements as shown in the drawings and do not limit the scope of the claims, unless expressly stated therein.

[0012] As used herein, the statement that two or more moieties are "bonded" together is intended to mean that the moieties are either directly joined together or are joined through one or more intermediate moieties.

[0013] FIG. 1 is a schematic diagram of a circuit breaker 10 (such as, but not limited to, a circuit breaker) according to an exemplary embodiment of the disclosed concepts. The circuit breaker 10 according to some exemplary embodiments can be configured to handle a 100A (I n =100A) rated device (i.e., rated current I n is 100 A). The circuit breaker 10 is configured to be electrically connected between a power source 2 and a load 4. The circuit breaker 10 protects the load 4, a circuit associated with the load 4, and components within the circuit breaker 10 by tripping or switching open to interrupt current flow to the load 4, for example, in the event of a fault condition (such as, but not limited to, an overcurrent condition).

[0014] The circuit breaker 10 includes a solid-state switch assembly 200 including a solid-state switch module 202 and a current sensor 206. The circuit breaker 10 also includes a gate driver circuit 204 and an analog trip circuit 208 associated with the solid-state switch assembly 200. The circuit breaker 10 further includes an operating mechanism 300, separable contacts 302, an electronic trip unit 304, and a power supply 100. In addition, the circuit breaker 10 includes position sensors 500, 502, 504, and a close button 506 and an open button 508. Those skilled in the art will appreciate that the circuit breaker 10 need not include all of these components. For example, in an exemplary embodiment, the circuit breaker 10 may include only a subset of these components without departing from the scope of the disclosed concepts.

[0015] The circuit breaker 10 is configured to provide solid-state circuit interruption via the solid-state switch assembly 200 and galvanic isolation via the separable contacts 302. The solid-state switch module 202 includes one or more solid-state switches (such as, but not limited to, metal-oxide semiconductor field effect transistors (MOSFETs), insulated gate bipolar transistors (IGBTs), or other solid-state switches electrically connected between the power source 2 and the load 4). The solid-state switch module 202 has a closed state in which power can flow through the solid-state switch module 202 between the power source 2 and the load 4, and an open state in which power is prevented from flowing between the power source 2 and the load 4.

[0016] The gate driver circuit 204 is configured to control the state of the solid-state switch module 202. The gate driver circuit 204 has a desaturation (DESAT) function that changes from an OFF state to an ON state when the current flowing through the solid-state switch module 202 reaches a predetermined threshold level. In an exemplary embodiment, the predetermined threshold level is approximately 2250 A (22.5×I n ). The DESAT function operates by monitoring the forward voltage drop of the solid-state switch in the solid-state switch module 202. When the forward voltage drop reaches a threshold level, the DESAT function changes to an ON state and the gate driver circuit 204 responds by changing the solid-state switch module 202 to an open state, interrupting the current flowing through the circuit breaker 10. In an exemplary embodiment, the DESAT function has a threshold voltage of 9V. Based on the on-resistance of a silicon carbide (SiC) MOSFET, the forward voltage drop reaches 9V when the current level is about 2250A. Thus, when the current flowing through the solid-state switch module 202 reaches about 2250A, the DESAT function changes to an ON state. It will be understood that these thresholds are provided by way of example only. Different thresholds may be used without departing from the scope of the disclosed concepts.

[0017] The DESAT function of the gate driver circuit 204 is used to open the solid-state switch module 202 to enable very rapid interruption of the current flowing through the circuit breaker 10. In some exemplary embodiments of the disclosed concepts, the interruption based on the DESAT function can be within 0.5 microseconds. In some exemplary embodiments of the disclosed concepts, the gate driver circuit 204 includes a capacitor configured to vary the interruption based on the DESAT function. For example, the time to interruption based on the DESAT function is based on the capacitance of the capacitor. In this manner, the interruption time based on the DESAT function can be easily adjusted by changing the capacitor.

[0018] In some exemplary embodiments, the current sensor 206 is configured to provide a normal sensor output proportional to the current flowing through the circuit breaker 10 and an overcurrent detection (OCD) output that changes to an on state when the current flowing through the circuit breaker 10 reaches a threshold level. In exemplary embodiments, the current sensor 206 is a Hall effect sensor.

[0019] The analog trip circuit 208 is configured to receive the normal sensor output and the OCD output from the current sensor 206. The analog circuit 208 is electrically connected to the gate driver circuit 204 and configured to output a trip signal to the gate driver circuit 204. In response to the trip signal, the gate driver circuit 204 controls the solid-state switch module 202 to change to an open state to interrupt the current flowing through the circuit breaker 10. The analog trip circuit 208 is configured to output a trip signal in response to the normal sensor output reaching a threshold level or the OCD output changing to an ON state. The analog trip circuit 208 is configured to output a trip signal in response to the OCD output changing to an ON state within a first predetermined period of time and to output a trip signal in response to the normal sensor output reaching a threshold level within a second predetermined period of time. In an exemplary embodiment, the first predetermined period of time is less than the second predetermined period of time. In an exemplary embodiment, the first predetermined period of time is 10 nanoseconds and the second predetermined period of time is 100 nanoseconds. It will be understood, however, that other predetermined time periods may be employed without departing from the scope of the concepts of the present disclosure. In an exemplary embodiment, interruption of the current flowing through the circuit breaker 10 based on the normal sensor output reaching a threshold level occurs within 4 microseconds, and interruption based on the OCD output occurs within 2 microseconds. It will be understood, however, that these are exemplary times, and that other times may be employed without departing from the scope of the concepts of the present disclosure. In some exemplary embodiments, the threshold level associated with the normal current sensor output is approximately 200 (2×I n )~750A(7.5×I n ) and the threshold level associated with the OCD output is approximately 750A (7.5×I n ), however, it will be understood that these are merely example values ​​and may be adjusted without departing from the scope of the concepts of the present disclosure.

[0020] Using the analog trip circuit 208 and the DESAT function of the gate driver circuit 204, a three level trip logic can be used within the circuit breaker 10. The DESAT function provides the fastest trip based on the highest current threshold, the OCD output provides the second fastest trip based on the second highest current threshold, and the normal sensor output provides the third fastest trip based on the third highest current threshold. In an exemplary embodiment, the highest current threshold is approximately 2250 A (22.5×I n ), with the fastest interruption occurring within 0.5 microseconds, and the second highest current threshold being approximately 750 A (7.5 × I n ), the second fastest shutoff is within 2.5 microseconds, and the third highest current threshold is approximately 200 (2 × I n )~750A(7.5×I n ), and the third fastest tripping is within 4 microseconds. The analog trip circuit 208 and the DESAT function of the gate driver circuit 204 allow tripping to occur faster than digital circuit protection such as that provided by the electronic trip unit 304.

[0021] In some exemplary embodiments of the disclosed concepts, the electronic trip unit 304 is also configured to output a trip signal to the gate driver circuit 204 to cause the gate driver circuit 204 to control the solid-state switch module 202 to change to an open state. The electronic trip unit 304 may output the trip signal based on a current threshold less than a third highest current threshold associated with a trip based on a normal sensor output by the analog trip circuit 208. The electronic trip unit 304 may be configured to output the trip signal based on an It trip curve, such that when the electronic trip unit 304 detects a fault condition based on the normal sensor output of the current sensor 206, the electronic trip unit 304 outputs the trip signal to the gate driver circuit 204 at a time associated with a current level based on the It trip curve.

[0022] The circuit breaker 10 also includes an operating mechanism 300 and a separable contact 302. The separable contact 302 is configured to open and provide galvanic isolation between the power source 2 and the load 4. The operating mechanism 300 is a structure that opens and closes the separable contact 302. For example, the operating mechanism 300 may include a movable arm that, when moved, causes the separable contact 302 to open and close. The electronic trip unit 304 is configured to control the operating mechanism 300 to open the separable contact 302. For example, the electronic trip unit 304 may be configured to control the operating mechanism 300 to open the separable contact 302 only after the solid-state switch module 202 changes to an open state. For example, in a mechanical circuit breaker, the separable contact is designed to interrupt the current flowing through the circuit breaker and has associated components such as arc chutes to manage arcs as a result of the circuit interruption. The circuit breaker 10 is a solid-state circuit breaker in which the current is interrupted by the solid-state switch module 202. The separable contacts 302 do not need to be designed to interrupt current, but rather need not have associated arc chutes or other components, since they are only intended to open after the solid-state switch module 202 interrupts current. Thus, the electronic trip unit 304 can be configured to control the operating mechanism 300 to open the separable contacts 302 only after the solid-state switch module 202 changes to an open state. Similarly, the electronic trip unit 304 can be configured to cause the gate driver circuit 204 to change the solid-state switch module 202 to a closed state only after the separable contacts 302 are closed. In this manner, bouncing arcs due to bouncing of the separable contacts 302 are prevented. In some exemplary embodiments, the separable contacts 302 are closed with manual intervention by a user, for example, via a reset switch. In some exemplary embodiments, the operating mechanism 300 is configured to close the separable contacts 302 in response to a close signal from the electronic trip unit 304.

[0023] In some exemplary embodiments of the disclosed concepts, the circuit breaker 10 includes a position sensor 500. The position sensor 500 is configured to sense whether the separable contacts 302 are in an open or closed position. An output of the position sensor 500 can be provided to the electronic trip unit 304. Based on the output of the position sensor 500, the electronic trip unit 304 can determine the position of the separable contacts 302. Similarly, the electronic trip unit 304 can receive outputs of the gate driver circuit 204 indicative of the state of the solid-state switch module 202. With these outputs, the electronic trip unit 304 can ensure that the separable contacts 302 are opened only after the solid-state switch module 202 has changed to an open state, and that the solid-state switch module 202 is changed to a closed state only after the separable contacts 302 have closed.

[0024] In some exemplary embodiments, the circuit breaker 10 includes a close button 506 and an open button 508. It will be appreciated that the buttons are used as an example. However, it will be appreciated that other user-actuable elements may be employed without departing from the scope of the concepts of the present disclosure. In exemplary embodiments, the electronic trip unit 304 is configured to control the operating mechanism 300 to close the separable contacts 302 and output a close signal to the gate driver circuit 204 to cause the gate driver circuit 204 to change the solid-state switch module 202 to a closed state in response to actuation of the close button 506. In exemplary embodiments, the electronic trip unit 304 is configured to output a trip signal to the gate driver circuit 204 to cause the gate driver circuit 204 to change the solid-state switch module 202 to an open state, and then control the operating mechanism 300 to open the separable contacts 302 in response to actuation of the open button 508. In some exemplary embodiments, position sensor 502 may be used to detect actuation of close button 506 and position sensor 504 may be used to detect actuation of open button 508. Electronic trip unit 304 may be configured to receive the output of position sensors 502, 504 and detect actuation of close button 506 and open button 508 based on the output of position sensors 502, 504.

[0025] The position sensors 500, 502, 504 may be any suitable type of sensor for detecting the position of a component. As an example, the position sensors 500, 502, 504 may be microswitches that are actuated by the movement of the corresponding component. For example, the position sensor 500 may be a microswitch disposed by a movable arm of the operating mechanism 300, such that the movement of the movable arm that opens or closes the separable contacts 302 actuates the position sensor 500, and based on the output of the position sensor 500, the electronic trip unit 304 can detect the current position of the separable contacts 302. Similarly, the position sensors 502, 504 may be microswitches disposed such that actuation of the on button 506 and the off button 508 actuates the position sensors 502, 504, respectively.

[0026] The power supply 100 is configured to receive power from the power source 2 and convert the power from the power source 2 into power usable by the components of the circuit breaker 10. For example, the power supply 100 can convert AC power from the power source 2 into DC power usable by the components of the circuit breaker 10. The power from the power supply 100 can provide power to operate components such as, for example, but not limited to, the electronic trip unit 304, the gate driver circuit 204, the operating mechanism 300 (e.g., a solenoid included in the operating mechanism), the current sensor 206, and the analog trip circuit 208. The power supply 100 can generate DC power at multiple voltages (e.g., but not limited to, 24V, 15V, 5V, and 3.3V). In an exemplary embodiment, the power supply 100 may be omitted and power to operate the components of the circuit breaker 10 may be provided by an external power supply. In some exemplary embodiments, the electronic trip unit 304 is configured to cause the solid-state switch module 202 to change to an open state and open the separable contacts 302 when power is not available from the power supply 100 or an external power supply. In some exemplary embodiments, the power supply 100 is configured to use a line-to-line voltage from the power source 2 to generate DC power used by the components of the circuit breaker 10. For example, rather than being connected between a line and neutral conductor, the power supply 100 is instead connected between multiple line conductors. Although FIG. 1 illustrates a single pole of the circuit breaker 10, it will be understood that the circuit breaker 10 can have multiple poles with multiple line phases of power flowing through the circuit breaker 10 with the power supply 100 connected to multiple line phases.

[0027] 2 is a circuit diagram of a power supply 100 according to an exemplary embodiment of the disclosed concepts. In this exemplary embodiment, the power supply 100 includes a three-phase line input 110, a rectifier diode bridge 120, a filtering circuit 130, a DC / DC converter 140, and an output 150. The three-phase line input 110 receives power from multiple line phases and provides a line-to-line AC voltage input to the rectifier diode bridge 120. The rectifier diode bridge 120 converts the AC voltage to a DC voltage and outputs the DC voltage to the filtering circuit 130. The filtering circuit 130 protects the power supply circuit 100 from current input surges by limiting the current input and filters the DC voltage via a current divider (C10, C11, C12, C13, R1, R2, R3, and R4). The DC / DC converter 140 receives the filtered DC voltage from the filtering circuit 130 and converts the filtered high DC voltage to a low DC voltage, for example, 24V, 15V, 5V, or 3.3V. The DC / DC converter 140 then outputs the low DC voltage to provide power to the components of the circuit breaker 10. The line voltage is stepped down to, for example, 24, 15, 5, or 3.3V DC to meet the voltage requirements of the electrical components of the circuit breaker 10. If no line voltage is available, an external 24V power supply can be used. If neither external power nor line voltage is present, the solid-state switch module 202 can change to an open state. Although FIG. 2 illustrates an example of a circuit used within the power supply 400, it will be understood that FIG. 2 is merely an exemplary embodiment. Circuit components can be rearranged, added, removed, or implemented differently without departing from the scope of the disclosed concepts.

[0028] 3A and 3B are circuit diagrams of an analog trip circuit 208 according to an exemplary embodiment of the disclosed concepts. The analog trip circuit 208 includes a normal sensor input 210 and an OCD input 212. The normal sensor input 210 is configured to receive a normal sensor output of the current sensor 206, which is proportional to the current flowing through the circuit breaker 10. The OCD input 212 is configured to receive the OCD output of the current sensor 206. The analog trip circuit 208 also includes a trip signal output 214 electrically connected to the gate driver circuit 204. In response to the normal sensor output reaching a threshold level or the OCD output changing to an on state, the analog trip circuit 208 is configured to output a trip signal at the output 214. The analog trip circuit 208 is configured to compare the normal sensor output to a threshold level, whereas the OCD output does not need to be compared to a threshold level. By avoiding this check on the OCD output, the analog trip circuit 208 can output a trip signal based on the OCD output faster than a trip signal based on a normal sensor output. Figures 3A and 3B show examples of logic circuitry used in the analog trip circuit 208. However, it will be understood that the examples shown in Figures 3A and 3B are merely exemplary implementations of the analog trip circuit 208. It will be understood that circuit components may be rearranged, added, removed, or implemented differently without departing from the scope of the disclosed concepts.

[0029] 4A and 4B are circuit diagrams of a gate driver circuit 204 according to an exemplary embodiment of the disclosed concepts. The gate driver circuit 204 includes an enable input 216 and a DESAT input 222. The gate driver circuit 204 also includes a driver output 224 and a fault output 218. The gate driver circuit 204 further includes a driver 220 and a capacitor 226. The enable input 216 is electrically connected to the analog trip circuit 208 and the electronic trip unit 304. The driver output 224 and the DESAT input 222 are electrically connected to the solid-state switch module 202. The fault output 218 is electrically connected to the electronic trip unit 218. The solid-state switch module 202 is configured to change between an open state and a closed state based on the driver output 224. The driver 220 is configured to control the state of the driver output 224 based on a trip signal received at the enable input 216 or the DESAT input 222. The driver 220 is configured to perform a DESAT function based on the DESAT of the input 222. The timing associated with changing the driver output 224 based on the DESAT input 222 is based in part on the capacitance of the capacitor 226. The driver 220 is also configured to control the state of the fault output 218, so that the electronic trip unit 304 can be notified when the gate driver circuit 204 controls the solid-state switch module 202 to change to an open or closed state. It will be understood that the examples shown in Figures 4A and 4B are merely exemplary implementations of the gate driver circuit 204. It will be understood that circuit components can be rearranged, added, removed, or implemented differently without departing from the scope of the disclosed concepts.

[0030] 5A and 5B are partial assembly views of the circuit breaker 10 according to an exemplary embodiment of the disclosed concepts. 5A and 5B show examples of the close button 506 and the open button 508, the position sensors 502, 504, a portion of the operating mechanism 300, and a portion of the separable contacts 302. In the example shown in FIG. 5A and 5B, a three-pole operating mechanism 300 is shown with a movable rotating arm that moves the separable contacts 302 in combination. The position sensors 502, 504 are associated with the close button 506 and the open button 508, respectively, such that actuation of the on button 506 and the off button 508 actuates the position sensors 502, 504. For example, protrusions are attached to the on button 506 and the off button 508 and move in conjunction with actuation of the close button 506 and the open button 508. As an example, a protrusion associated with the on button 508 may move relative to the position sensor 504 when the close button 508 is actuated. Figures 5A and 5B show a portion of the separable contacts 302. In particular, Figures 5A and 5B show a moving contact of the separable contacts 302. It will be understood that a stationary contact is associated with the moving contact. By moving the moving contact away from the stationary contact, the separable contacts 302 are opened.

[0031] Figures 6A and 6B are partial assembly views of a circuit breaker 10 according to an exemplary embodiment of the disclosed concepts. Figure 6A shows a portion of the operating mechanism 300 and the separable contacts 302 in a closed position. Figure 6B shows a portion of the operating mechanism and the separable contacts 302 in an open position. Figures 6A and 6B also show a position sensor 500 configured to sense whether the separable contacts 302 are in a closed or open position. The position sensor 500 can be associated with a portion of a movable arm of the operating mechanism 300 such that the movable arm abuts the position sensor when the separable contacts 302 are in a closed position and moves away from the position sensor 500 when the separable contacts 302 are in an open position.

[0032] 7 is a partially exploded front view of the circuit breaker 10 according to an exemplary embodiment of the disclosed concepts. FIG 7 illustrates the close button 506 and the open button 508, as well as a status indicator 510 indicating the position of the separable contacts 302 according to an exemplary embodiment of the disclosed concepts.

[0033] 8 is a partial interior side view of the circuit breaker 10 in accordance with an exemplary embodiment of the disclosed concepts. The current path 600 through the circuit breaker is indicated by the arrows. As shown in FIG. 8, current flowing from the power source 2 through the circuit breaker 10 first flows through the separable contacts 302. The current then continues through the solid-state switch assembly 200 and the current sensor 206 located proximate the output of the solid-state switch assembly 200 and is then provided to the load 4.

[0034] 9A-9C are diagrams of a solid-state switch assembly 200 according to an exemplary embodiment of the disclosed concepts. The solid-state switch assembly 200 includes a solid-state switch module 202 and a current sensor 206. The solid-state switch assembly 200 also includes an input terminal 250 and an input conductor 252. The input terminal 250 is configured to receive power from a power source 2 via a separable contact 302 and provide power to the solid-state switch module 202 via the input conductor 252. The solid-state switch assembly 200 also includes an output terminal 256 and an output conductor 254. When the solid-state switch module 202 is in a closed state, power flows through the solid-state switch module 202 to the load conductor 254 and then to the output terminal 256. The output terminal 256 is configured to be electrically connected to the load 4. The solid-state switch assembly 200 also includes a module cover 258.

[0035] In Figure 9C, the module cover 258 has been omitted. The solid-state switch assembly 200 also includes an MOV 262, shown in Figure 9C covered by the module cover 258.

[0036] The solid-state switch assembly 200 further includes a heat sink 260. The heat sink 260 is attached to the solid-state switch module 200 and is further described with respect to Figures 10A-10D.

[0037] 10A and 10B are diagrams of a heat sink 260 and 10C and 10D are diagrams of a solid-state switch module 202 attached to the heat sink 260 in accordance with an exemplary embodiment of the disclosed concepts. The heat sink 260 includes a first planar member 264 and a second planar member 268 extending from one side of the first planar member 264. The heat sink 260 also includes a plurality of protrusions 270 extending from an opposite side of the first planar member 264.

[0038] 10C and 10D. In an exemplary embodiment, fasteners 272 can be used to attach the solid-state switch member 202 to the second planar member 268. The heat sink 260 can be constructed from a metallic material and is operable to dissipate heat generated by the solid-state switch module 202.

[0039] 11A and 11B are diagrams of a frame 280 for housing solid-state switch assemblies 200 according to an exemplary embodiment of the disclosed concepts. The frame 280 includes compartments 282, each compartment housing one solid-state switch assembly 200. In the exemplary embodiment shown in FIGS. 11A and 11B, the frame 280 includes three compartments 282 housing three solid-state switch assemblies 200. Each solid-state switch assembly 200 may correspond to a pole of the circuit breaker 10. Thus, the frame 280 is suitable for use in a three-pole circuit breaker. However, it will be understood that the frame 280 may be modified to have a different number of compartments 282 without departing from the scope of the disclosed concepts.

[0040] The solid-state switch assembly 200 has a modular design. The components of the solid-state switch assembly 200 can be replaced with other similarly molded components depending on the application of the solid-state switch assembly 200. For example, the solid-state switch module 202 can be replaced with another solid-state switch module 202 for applications having different voltage and current requirements. The remaining components of the solid-state switch assembly 200 can remain unchanged, thus allowing the solid-state switch assembly 200 to be more widely applied without having to redesign the entire solid-state switch assembly 200. Similarly, the current sensor 206 may be replaced with another current sensor 206 in applications having different current requirements. Similarly, other components of the solid-state switch assembly 200 may also be replaced.

[0041] 12 is a flow chart of a method of operating a circuit breaker in accordance with an exemplary embodiment of the concepts of the present disclosure. The method may be performed, for example, on the circuit breaker 10 described herein. Solid-state circuit breakers, such as the circuit breaker 10, introduce new concerns regarding health and remaining life compared to mechanical circuit breakers. For example, monitoring the health of a solid-state switch is different from monitoring the health of a mechanical switch. However, in both cases, it is important to monitor when the switch has reached the end of its life and is at risk of failure.

[0042] The method of FIG. 12 begins at 700 with monitoring a characteristic of the solid-state switch assembly 200. In some exemplary embodiments, the solid-state switch module 202 is monitored. In some exemplary embodiments, the MOV 262 is monitored. It will be appreciated that both may be monitored. The monitored characteristic may be the junction temperature of the solid-state switch, the forward voltage drop (for an IGBT solid-state switch), the body diode forward voltage drop (for a MOSFET solid-state switch), the gate threshold voltage (for a MOSFET solid-state switch), or the gate leakage current (for a MOSFET solid-state switch). The monitored characteristic may also be the voltage across the MOV 262.

[0043] At 702, it is determined whether the monitored characteristic exceeds a threshold level. The threshold level may be selected based on the monitored characteristic and the device being monitored. In the case of the voltage across MOV 262, the threshold may be a time varying range. For example, the voltage across MOV 262 may be monitored for a period of time after a solid state switch is opened. The threshold range varies over the period of time to determine whether the voltage across MOV 262 is outside the threshold range at a particular time. If the characteristic does not exceed the threshold level, the method returns to 700. However, if the characteristic does exceed the threshold level, the method proceeds to 704.

[0044] At 704, an indication is provided. The indication may be via a display on the circuit breaker 10 or any other suitable type of indication, such as, for example, an LED indicator, wired or wireless communication, etc. The indication notifies a user or technician that the component needs to be serviced or replaced. It will be appreciated that additional method steps may be employed to service or replace the component, or to control the circuit breaker 10 to switch open, in response to determining that the monitored characteristic exceeds a threshold level.

[0045] Junction temperature is an indicator of the health of a solid-state switch. As an example, some solid-state switches should be kept below a threshold junction temperature of 150°C. If the junction temperature reaches this threshold, the solid-state switch will be damaged and may fail. Therefore, the junction temperature of a solid-state switch is a useful characteristic to monitor.

[0046] The forward voltage drop or body diode forward voltage drop is also an indicator of the health of a solid-state switch. If the forward voltage drop or body diode forward voltage drop reaches a threshold when operating at rated current, the solid-state switch may be damaged and fail. The forward voltage drop or body diode forward voltage drop may be caused by several factors, such as high current, poor heat conduction, or improper thermal management. Therefore, the forward voltage drop and body diode forward voltage drop are useful characteristics to monitor.

[0047] The gate threshold voltage or gate leakage current are also useful characteristics of a solid-state switch to monitor. A gate threshold voltage or gate leakage current exceeding a threshold level can damage or cause a solid-state switch to fail. The gate leakage current is more sensitive to degradation of the solid-state switch and can be monitored while the solid-state switch is closed and conducting current, making it more practical to monitor than the gate threshold voltage. However, both the gate threshold voltage and gate leakage current are useful characteristics to monitor to determine the health of a solid-state switch.

[0048] As MOV262 begins to degrade, the voltage across MOV262 will increase or decrease. MOV262 clamps the voltage for a period of time after the solid-state switch is opened, and therefore this period is the relevant period for monitoring the voltage across MOV262. An exemplary threshold range may be ±10% of the normal clamp voltage of MOV262. For example, the voltage across MOV262 drifting more than 10% from the normal clamp voltage is an indicator that MOV262 is degraded and should be serviced or replaced. Thus, the voltage across MOV262 is another useful characteristic to monitor.

[0049] Although several examples of monitored characteristics have been described, it will be understood that other characteristics may be monitored without departing from the scope of the disclosed concepts. It will also be understood that in addition to, or instead of, providing an indication, additional actions may be performed in response to a characteristic crossing a threshold.

[0050] Although specific embodiments of the concepts of the present disclosure have been described in detail, those skilled in the art will appreciate that various modifications and alternatives to those details may be developed in light of the overall teachings of the present disclosure. Accordingly, the particular arrangements disclosed are meant to be merely illustrative and not limiting as to the scope of the concepts of the present disclosure, which is given the full scope of the appended claims and any and all equivalents thereof.

Claims

1. 1. A circuit breaker configured to provide an electrical connection between a power source and a load, comprising: a current sensor configured to sense a current flowing through the circuit breaker and having a normal sensor output proportional to the current flowing through the circuit breaker and an overcurrent detection (OCD) output that changes to an on state when the current flowing through the circuit breaker reaches a second threshold level; a solid state switch module configured to have a closed state that allows current to flow through the circuit breaker and an open state that interrupts current flow to the circuit breaker; a gate driver configured to control the solid state switch module to interrupt current flow through the circuit breaker, the gate driver including a desaturation (DESAT) function output that changes to an on state when the current flowing through the circuit breaker reaches a third threshold level, the gate driver configured to cause the solid state switch module to interrupt current flow through the circuit breaker when the DESAT function output changes to the on state; an analog trip circuit configured to receive the normal sensor output and the OCD output and output a trip signal to the gate driver when the normal sensor output reaches a first threshold level or the OCD output changes to the on state, the trip signal causing the gate driver to control the solid state switch module to control current flow through the circuit breaker; and A circuit breaker comprising:

2. 2. The circuit breaker of claim 1, wherein the analog trip circuit is configured to output the trip signal based on the normal sensor output such that the solid state switch module interrupts the current through the circuit breaker within a first predetermined time period and is configured to output the trip signal based on the OCD output such that the solid state switch module interrupts the current through the circuit breaker within a second predetermined time period, and the gate driver is configured to cause the solid state switch module to interrupt the current through the circuit breaker based on the DESAT function output within a third predetermined time period, the third predetermined time period being less than the second predetermined time period and the second predetermined time period being less than the first predetermined time period.

3. 3. The circuit breaker of claim 2, wherein the first predetermined period of time is approximately 4 microseconds, the second predetermined period of time is approximately 2.5 microseconds, and the third predetermined period of time is approximately 0.5 microseconds.

4. 3. The circuit breaker of claim 2, wherein the analog trip circuit is configured to output the trip signal based on the normal sensor output within about 100 nanoseconds of receiving the normal sensor output, and the analog trip circuit is configured to output the trip signal based on the OCD output within about 10 nanoseconds of receiving the OCD output.

5. 3. The circuit breaker of claim 2, wherein the gate driver includes a capacitor, and the third predetermined period is based in part on a capacitance of the capacitor.

6. 2. The circuit breaker of claim 1, wherein the first threshold level is within a range of about 2 times the rated current of the circuit breaker to about 7.5 times the rated current, the second threshold level is about 7.5 times the rated current, and the third threshold level is about 22.5 times the rated current.

7. 2. The circuit breaker of claim 1, wherein said DESAT function output is based on a voltage drop across a solid-state switch in said solid-state switch module based on a level of current flowing through said solid-state switch module.

8. The circuit breaker of claim 1 , wherein the current sensor is a Hall effect sensor.

9. 10. The circuit breaker of claim 1, wherein the solid state switch module includes at least one solid state switch.

10. A separable contact; an operating mechanism configured to open the separable contacts; Further comprising:

10. The circuit breaker of claim 1, wherein opening the separable contacts provides galvanic isolation between the power source and the load.

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