Solid state circuit interrupter

Abstract

To provide a circuit interrupter for over current detection that has a solid state switch module.SOLUTION: A circuit interrupter 10 includes: a current sensor having a normal sensor output and an over current detection output; a solid state switch module 202 structured to have a closed state to allow current to flow through the circuit interrupter 10 and an open state to interrupt current flowing through the circuit interrupter 10; a gate driver 204 structured to control the solid state switch module 202 including a desaturation function output, wherein the gate driver is structured to cause the solid state switch module 202 to interrupt current flowing through the circuit interrupter 10 when the DESAT function output changes to the on state; and an electronic trip unit 304 structured to output a trip signal to the gate driver 204 when the normal sensor output reaches a first threshold level or the overcurrent detection output changes to the on state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application is related to U.S. Patent Application No. 16 / 775,985, "SOLID STATE CIRCUIT INTERRUPTER" (Attorney Docket No. 19 - ETU - 783 - 2), filed on January 29, 2020, by the same applicant as a co - pending application.

[0002] (Field of the Invention) The disclosed concepts generally relate to circuit breakers, and more particularly, to solid - state circuit breakers.

Background Art

[0003] For example, but not limited to, circuit breakers such as circuit breakers are typically used to protect electrical circuits from damage caused by over - current conditions such as overload conditions, short - circuits, or other fault conditions such as arc faults or ground faults. Solid - state circuit breakers use solid components, such as semiconductor devices, to switch the current flowing from a power source to a load on and off.

[0004] Solid - state circuit breakers provide faster tripping than conventional mechanical circuit breakers. However, these capabilities are not being optimally utilized. Further, solid - state circuit breakers present different safety and reliability concerns than conventional mechanical circuit breakers. There is significant room for improvement in solid - state circuit breakers.

Summary of the Invention

[0005] According to one aspect of the disclosed concept, a circuit breaker configured to electrically connect a power source and a load includes a current sensor configured to detect a current flowing through the circuit breaker, 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 in which current can flow through the circuit breaker and an open state in which the current flowing through the circuit breaker is interrupted; a gate driver configured to control the solid-state switch module to interrupt the current flowing through the circuit breaker, 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, and configured to cause the solid-state switch module to interrupt the current flowing 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 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 interrupt the current flowing through the circuit breaker.

[0006] According to one aspect of the disclosed concept, a circuit breaker configured to electrically connect a power source and a load includes a separable contact configured to open to provide galvanic insulation between the power source and the load, an operating mechanism configured to open and close the separable contact, a first position sensor configured to detect the position of the separable contact, a solid-state switch module configured to have a closed state in which current can flow through the circuit breaker and an open state in which the current flowing through the circuit breaker is interrupted, and an electronic trip unit configured to control the solid-state switch module to change between the open state and the closed state and to control the operating mechanism to open the separable contact. The electronic trip unit is configured to control the solid-state switch module based on the output of the first position sensor to change the solid-state switch module from the open state to the closed state when the separable contact is in the closed position.

[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 detect current flowing through the solid-state switch module, and several metal oxide varistors (MOVs).

[0008] According to one aspect of the disclosed concept, a circuit breaker includes a frame including several compartments and several solid-state switch assemblies. Each solid-state switch assembly is disposed in a corresponding one of the compartments and 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, a current sensor configured to detect current flowing through the solid, and several metal oxide varistors (MOVs).

[0009] According to one aspect of the disclosed concept, a method of operating a circuit breaker having a solid-state switch module including a solid-state switch includes monitoring characteristics of the solid-state switch, determining that the characteristics of the solid-state switch meet or exceed a predetermined threshold, and providing an indication in response to determining that the characteristics of the solid-state switch meet or exceed the predetermined threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A complete understanding of the concepts of the present disclosure can be obtained from the following best mode for carrying out the invention, when read in conjunction with the accompanying drawings.

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Best Mode for Carrying Out the Invention

[0011] Directional terms used herein, such as left, right, front, rear, top, bottom, and their variations, etc., relate to the orientation of the elements shown in the drawings and do not limit the scope of the claims unless explicitly stated therein.

[0012] As used herein, the description that two or more parts are “coupled” together shall mean that the parts are either directly joined together or joined through one or more intermediate parts.

[0013] FIG. 1 is a schematic diagram of a circuit breaker 10 (e.g., but not limited to, a circuit breaker) according to an exemplary embodiment of the disclosed concept. The circuit breaker 10 according to some exemplary embodiments is a 100 A (I n = 100 A) rated device (i.e., the 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 is operable to open or switch to an open state to interrupt the current flowing to the load 4, for example, in the event of a fault condition (e.g., but not limited to, an overcurrent condition), to protect the load 4, the circuits associated with the load 4, and the components within the circuit breaker 10.

[0014] The circuit breaker 10 includes a solid state switch assembly 200 that includes 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. Additionally, the circuit breaker 10 includes position sensors 500, 502, 504, as well as a close button 506 and an open button 508. It will be understood by those skilled in the art that the circuit breaker 10 need not include all of these components. For example, in an exemplary embodiment, the circuit breaker 10 can include only a subset of these components without departing from the scope of the disclosed concept.

[0015] The circuit breaker 10 is configured to provide interruption of a solid-state circuit via a solid-state switch assembly 200 and galvanic isolation via separable contacts 302. The solid-state switch module 202 includes one or more solid-state switches (e.g., but not limited to, a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT), or a solid-state switch 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 between the power source 2 and the load 4 through the solid-state switch module 202, and an open state in which power flow between the power source 2 and the load 4 is prevented.

[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 about 2250 A (22.5×I n ). The DESAT function operates by monitoring the forward voltage drop of the solid-state switches within the solid-state switch module 202. When the forward voltage drop reaches the threshold level, the DESAT function changes to the on state, and in response, the gate driver circuit 204 causes the solid-state switch module 202 to change to the open state, interrupting the current flowing through the circuit breaker 10. In an exemplary embodiment, the DESAT function has a threshold voltage of 9 V. Based on the on-resistance of a silicon carbide (SiC) MOSFET, when the current level is about 2250 A, the forward voltage drop reaches 9 V. Thus, when the current flowing through the solid-state switch module 202 reaches about 2250 A, the DESAT function changes to the on state. It will be understood that these thresholds are provided merely as an example, and different thresholds can be used without departing from the scope of the disclosed concept.

[0017] Use the DESAT function of the gate driver circuit 204 to open the solid state switch module 202 to enable a very rapid interruption of the current flowing through the circuit breaker 10. In some exemplary embodiments of the disclosed concept, the interruption based on the DESAT function can be within 0.5 microseconds. In some exemplary embodiments of the disclosed concept, the gate driver circuit 204 includes a capacitor configured to vary the interruption based on the DESAT function. For example, the time until the interruption based on the DESAT function is based on the capacitance of the capacitor. In this way, 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 an exemplary embodiment, the current sensor 206 is a Hall effect sensor.

[0019] The analog trip circuit 208 is configured to receive a normal sensor output and an OCD output from the current sensor 206. The analog circuit 208 is electrically connected to the gate driver circuit 204 and is 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, cutting off 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 and to output a trip signal in response to the normal sensor output reaching the threshold level within a second predetermined period. In an exemplary embodiment, the first predetermined period is less than the second predetermined period. In an exemplary embodiment, the first predetermined period is 10 nanoseconds and the second predetermined period is 100 nanoseconds. However, it will be understood that other predetermined periods may be employed without departing from the scope of the concepts of the present disclosure. In an exemplary embodiment, the interruption of the current flowing through the circuit breaker 10 based on the normal sensor output reaching the threshold level occurs within 4 microseconds, and the interruption based on the OCD output occurs within 2 microseconds. However, these are exemplary times, and it will be understood 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 in the range of approximately 200 (2×I n ) to 750 A (7.5×I n ), and the threshold level associated with the OCD output is approximately 750 A (7.5×I n ). However, these are merely exemplary values, and it will be understood that they may be adjusted without departing from the scope of the concepts of the present disclosure.

[0020] Using the DESAT functions of the analog trip circuit 208 and the gate driver circuit 204, three levels of cutoff logic can be used within the circuit breaker 10. The DESAT function provides the fastest cutoff based on the highest current threshold, the OCD output provides the second-fastest cutoff based on the second-highest current threshold, and the normal sensor output provides the third-fastest cutoff based on the third-highest current threshold. In an exemplary embodiment, the highest current threshold is about 2250 A (22.5×I n ), the fastest cutoff is within 0.5 microseconds, the second-highest current threshold is about 750 A (7.5×I n ), the second-fastest cutoff is within 2.5 microseconds, the third-highest current threshold is in the range of about 200 (2×I n ) to 750 A (7.5×I n ), and the third-fastest cutoff is within 4 microseconds. Due to the DESAT functions of the analog trip circuit 208 and the gate driver circuit 204, the cutoff can occur faster than digital circuit protection 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 control the solid state switch module 202 of the gate driver circuit 204 to change to an open state. The electronic trip unit 304 can output a trip signal based on a current threshold below the third-highest current threshold associated with a trip based on the normal sensor output of the analog trip circuit 208. The electronic trip unit 304 may be configured to output a trip signal based on an I-t 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 a trip signal to the gate driver circuit 204 at a point in time associated with the current level based on the I-t trip curve.

[0022] The circuit breaker 10 also includes an operating mechanism 300 and separable contacts 302. The separable contacts 302 are configured to be opened to provide galvanic insulation between the power supply 2 and the load 4. The operating mechanism 300 is structured to open and close the separable contacts 302. For example, the operating mechanism 300 can include a movable arm that opens and closes the separable contacts 302 when it moves. The electronic trip unit 304 is configured to control the operating mechanism 300 to open the separable contacts 302. For example, 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 has changed to the open state. For example, in a mechanical circuit breaker, the separable contacts are designed to interrupt the current flowing through the circuit breaker and have related components such as an arc chute for managing the arc 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 need not be designed to interrupt the current and are only intended to open after the solid-state switch module 202 has interrupted the current, so they need not have related arc chutes or other components. Therefore, 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 has changed to the open state. Similarly, the electronic trip unit 304 can be configured to change the solid-state switch module 202 to the closed state in the gate driver circuit 204 only after the separable contacts 302 have been closed. In this way, bounce arcs due to the bounce of the separable contacts 302 are prevented. In some exemplary embodiments, the separable contacts 302 are closed, for example, by manual intervention by the user 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 detect whether the separable contact 302 is in the open position or the closed position. The 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 contact 302. Similarly, the electronic trip unit 304 unit can receive the output of the gate driver circuit 204 indicating the state of the solid state switch module 202. With these outputs, the electronic trip unit 304 can ensure that the separable contact 302 is opened only after the solid state switch module 202 has changed to the open state, and that the solid state switch module 202 is changed to the closed state only after the separable contact 302 has been closed.

[0024] In some exemplary embodiments, the circuit breaker 10 includes a close button 506 and an open button 508. It will be understood that the buttons are used as an example. However, it will be understood that other user-operable elements may be employed without departing from the scope of the concepts of the present disclosure. In an exemplary embodiment, the electronic trip unit 304 controls the operating mechanism 300 to close the separable contacts 302, outputs a close signal to the gate driver circuit 204, and is configured to change the solid state switch module 202 to a closed state in the gate driver circuit 204 in response to the actuation of the close button 506. In an exemplary embodiment, the electronic trip unit 304 outputs a trip signal to the gate driver circuit 204 to change the solid state switch module 202 to an open state in the gate driver circuit 204, and then controls the operating mechanism 300 to open the separable contacts 302 in response to the actuation of the open button 508. In some exemplary embodiments, a position sensor 502 can be used to detect the actuation of the close button 506, and a position sensor 504 can be used to detect the actuation of the open button 508. The electronic trip unit 304 can be configured to receive the outputs of the position sensors 502, 504 and detect the actuation of the close button 506 and the open button 508 based on the outputs of the 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 actuated by the movement of the corresponding component. For example, the position sensor 500 may be a microswitch disposed by the movable arm of the operating mechanism 300, whereby the movement of the movable arm that opens and 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 arranged such that the actuation of the on button 506 and the off button 508 actuates the position sensors 502, 504, respectively.

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

[0027] FIG. 2 is a circuit diagram of a power supply unit 100 according to an exemplary embodiment of the concept of the present disclosure. In this exemplary embodiment, the power supply unit 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 a plurality of line phases and provides an interphase AC voltage input to the rectifier diode bridge 120. The rectifier diode bridge 120 converts the AC voltage into a DC voltage and outputs the DC voltage to the filtering circuit 130. The filtering circuit 130 protects the power supply circuit 100 from an influx of current inputs by restricting the current input, and filters the DC voltage through current dividers (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 into 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 interphase voltage is stepped down to a DC of, for example, 24, 15, 5, or 3.3V to meet the voltage requirements of the electrical components of the circuit breaker 10. If the interphase voltage is not available, an external 24V power supply can be used. If neither external power nor interphase voltage is present, the solid-state switch module 202 can be changed to an open state. FIG. 2 shows an example of a circuit used within the power supply unit 400, but it will be understood that FIG. 2 is merely an exemplary embodiment. The circuit components can be rearranged, added, removed, or implemented differently without departing from the scope of the disclosed concept.

[0028] FIG. 3A and FIG. 3B are circuit diagrams of an analog trip circuit 208 according to an exemplary embodiment of the disclosed concept. 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 the normal sensor output of a current sensor 206 that 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 that is 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, although the OCD output need not be compared to a threshold level. By avoiding this check at 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 the normal sensor output. FIGS. 3A and 3B show examples of logic circuits used in the analog trip circuit 208. However, it will be understood that the examples shown in FIGS. 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 concept.

[0029] Figures 4A and 4B are circuit diagrams of a gate driver circuit 204 according to an exemplary embodiment of the disclosed concept. 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 an analog trip circuit 208 and an electronic trip unit 304. The driver output 224 and the DESAT input 222 are electrically connected to a 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 partially based on the capacitance of the capacitor 226. The driver 220 is also configured to control the state of the fault output 218, thereby enabling the electronic trip unit 304 to be notified when the solid state switch module 202 is controlled such that the gate driver circuit 204 changes to an open state or a closed state. It will be understood that the examples shown in FIGS. 4A and 4B are merely exemplary implementations of the gate driver circuit 204. It will be understood that circuit components may be rearranged, added, removed, or implemented differently without departing from the scope of the disclosed concept.

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

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

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

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

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

[0035] In FIG. 9C, module cover 258 is omitted. Solid state switch assembly 200 also includes MOV 262 shown in FIG. 9C, which is covered by 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 will be further described with respect to FIGS. 10A - 10D.

[0037] FIGS. 10A and 10B are diagrams of the heat sink 260 according to an exemplary embodiment of the disclosed concept, and FIGS. 10C and 10D are diagrams of the solid state switch module 202 attached to the heat sink 260 according to an exemplary embodiment of the disclosed concept. 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 the opposite side of the first planar member 264.

[0038] The solid state switch member 202 is configured to be attached to the second planar member 268 as shown in FIGS. 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 composed of a metallic material and is operable to dissipate heat generated by the solid state switch module 202.

[0039] FIGS. 11A and 11B are diagrams of a frame 280 for housing the solid state switch assembly 200 according to an exemplary embodiment of the disclosed concept. 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 and houses three solid state switch assemblies 200. Each solid state switch assembly 200 can 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 can be modified to have a different number of compartments 282 without departing from the scope of the disclosed concept.

[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 similar shaped 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 may remain unchanged, thus enabling the solid state switch assembly 200 to be applied more widely without the need 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 can also be replaced.

[0041] FIG. 12 is a flowchart of a method of operating a circuit breaker according to an exemplary embodiment of the concepts of the present disclosure. This method can be implemented, for example, in the circuit breaker 10 described herein. Solid state circuit breakers, such as circuit breaker 10, introduce new concerns regarding integrity and remaining life compared to mechanical circuit breakers. For example, monitoring the integrity of a solid state switch is different from monitoring the integrity of a mechanical switch. However, in both cases, it is important to monitor when the switch reaches the end of its life and is at risk of failure.

[0042] The method of FIG. 12 begins at 700 with monitoring the characteristics 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 understood that both can be monitored. The characteristics monitored may be the junction temperature of the solid state switch, the forward voltage drop (in the case of an IGBT solid state switch), the body diode forward voltage drop (in the case of a MOSFET solid state switch), the gate threshold voltage (in the case of a MOSFET solid state switch), or the gate leakage current (in the case of a MOSFET solid state switch). The characteristic monitored 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 can be selected based on the monitored characteristic and the device being monitored. In the case of the voltage across MOV262, the threshold may be a time-varying range. For example, the voltage across MOV262 can be monitored for a certain period after the solid-state switch is opened. The threshold range varies over time and determines whether the voltage across MOV262 is outside the threshold range at a particular point in time. If the characteristic does not exceed the threshold level, the method returns to 700. However, if the characteristic exceeds the threshold level, the method proceeds to 704.

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

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

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

[0047] The gate threshold voltage or the gate leakage current is also a characteristic of the solid-state switch useful for monitoring. A gate threshold voltage or a gate leakage current exceeding the threshold level may damage the solid-state switch or cause a failure of the solid-state switch. The gate leakage current is more sensitive to the deterioration of the solid-state switch and can be monitored while the solid-state switch is closed and conducting current, whereby monitoring is more practical than the gate threshold voltage. However, both the gate threshold voltage and the gate leakage current are characteristics useful for monitoring to determine the soundness of the solid-state switch.

[0048] When MOV262 begins to deteriorate, the voltage across MOV262 increases and decreases. MOV262 clamps the voltage for a certain period after the solid-state switch is opened, and thus this period is the period relevant to monitoring the voltage across MOV262. An exemplary threshold range may be ±10% of the normal clamping voltage of MOV262. For example, a voltage across MOV262 that drifts more than 10% from the normal clamping voltage is an indication that MOV262 is deteriorating and should be serviced or replaced. Therefore, the voltage across MOV262 is another characteristic useful for monitoring.

[0049] Although some examples of the characteristics to be monitored have been described, it will be understood that other characteristics may be monitored without departing from the scope of the disclosed concept. 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 exceeding a threshold.

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

Claims

1. A circuit breaker configured to electrically connect between a power source and a load, a solid state switch module configured to have a closed state in which current can flow through the circuit breaker and an open state in which the current flowing through the circuit breaker is interrupted; an overcurrent detector configured to detect an overcurrent flowing through the circuit breaker and having an overcurrent detection (OCD) output that changes to an on state when the overcurrent is detected; an analog trip circuit configured to receive the OCD output and output a first trip signal when the OCD output changes to the on state; a gate driver including an enable input configured to receive the first trip signal from the analog trip circuit and a desaturation (DESAT) function output that changes to an on state when the current flowing through the circuit breaker reaches a threshold current level, the gate driver being configured to operate the solid state switch module to interrupt the current flowing through the circuit breaker based at least in part on the first trip signal and the change of the DESAT function output to the on state; A circuit breaker comprising.

2. The circuit breaker according to claim 1, wherein the analog trip circuit outputs the first trip signal based on a change of the OCD output to the on state without comparing the detected overcurrent with a predetermined threshold.

3. The circuit breaker according to claim 2, wherein the first trip signal is output faster than a trip signal based on a sensor output that requires comparing a detected current with a predetermined threshold.

4. The circuit breaker according to claim 2, wherein the analog trip circuit outputs the trip signal within about 10 nanoseconds after receiving the OCD output.

5. The circuit breaker according to claim 1, wherein the DESAT function output changes to the on state when a forward voltage drop of the solid state switch module reaches a threshold voltage.

6. The circuit breaker according to claim 5, wherein the threshold voltage is reached when the current value is about 2250 A.

7. The circuit breaker according to claim 1, further comprising an electronic trip unit coupled to the enable input of the gate driver and the overcurrent detector.

8. The circuit breaker according to claim 7, wherein when the electronic trip unit detects a fault condition, it is configured to output a second trip signal to the enable input based on an I-t trip curve.

9. The interruption of the current flowing through the circuit breaker based on the first trip signal indicating a change of the DESAT function output to the on state and a change of the OCD output to the on state is faster than the interruption of the current flowing through the circuit breaker based on the second trip signal received from the electronic trip unit, according to claim 8.

10. The interruption of the current flowing through the circuit breaker based on a change of the DESAT function output to the on state occurs within 0.5 microseconds, according to claim 9.

11. The interruption of the current flowing through the circuit breaker based on the first trip signal indicating a change of the OCD output to the on state occurs within 2.5 microseconds, according to claim 9.

12. The interruption of the current flowing through the circuit breaker based on the second trip signal occurs at least 4 microseconds after the detection of the fault condition, according to claim 9.

13. The circuit breaker according to claim 6, wherein the gate driver further includes a fault output electrically connected to the electronic trip unit.

14. The circuit breaker according to claim 13, wherein the gate driver is further configured to notify the electronic trip unit when the gate driver controls the solid-state switch module to change to an open state or a closed state.

15. A high-speed trip method for a circuit breaker including a solid-state switch module, an overcurrent detector including an overcurrent detection (OCD) output, an analog trip circuit, an electronic trip unit, and a gate driver including a desaturation (DESAT) function output, the method comprising: monitoring at least one of the states of the OCD output and the DESAT function output; detecting a fault condition based at least in part on the monitored state; and causing the solid-state switch module to interrupt the current flowing through the circuit breaker based on the detected fault condition. Detecting the fault state includes detecting a change in the ON state of the DESAT function output or detecting a change in the ON state of the OCD output. The fault state is based on the change in the OCD output. Interrupting the current flowing through the circuit breaker to the solid state switch module includes interrupting the current within 2.5 microseconds. Method.

16. A high-speed trip method for a circuit breaker including a solid state switch module, an overcurrent detector including an overcurrent detection (OCD) output, an analog trip circuit, an electronic trip unit, and a gate driver including a desaturation (DESAT) function output, Monitoring at least one of the states of the OCD output and the DESAT function output, Detecting a fault state based at least in part on the monitored state, and Based on the detected fault state, interrupting the current flowing through the circuit breaker to the solid state switch module, Detecting the fault state includes detecting a change in the ON state of the DESAT function output or detecting a change in the ON state of the OCD output. Detecting the fault state is based on an I-t trip curve. The electronic trip unit outputs a trip signal to the gate driver based on the I-t trip curve. Method.

17. Interrupting the current flowing through the circuit breaker to the solid state switch module includes interrupting the current after at least 4 microseconds have elapsed after detecting the fault state based on the I-t trip curve. The method according to claim 16.

18. A circuit breaker configured to electrically connect a power source and a load, A solid state switch module configured to have a closed state in which current can flow through the circuit breaker and an open state in which the current flowing through the circuit breaker is interrupted, A current sensor configured to detect the current flowing through the circuit breaker, An electronic trip unit configured to output a trip signal when detecting a fault state based on the output of the current sensor, A gate driver circuit including an enable input electrically connected to the electronic trip unit and a desaturation (DESAT) input electrically connected to the solid state switch module, the gate driver circuit being configured to receive the trip signal at the enable input and execute a DESAT function based on a signal received at the DESAT input from the solid state switch module, the DESAT function monitoring a forward voltage drop of a solid state switch of the solid state switch module and controlling a state of the solid state switch module to change from an off state to an on state when a current flowing through the solid state switch module reaches a predetermined threshold level, the gate driver circuit and, separable contacts, an operating mechanism configured to open and close the separable contacts, and including, The electronic trip unit is configured to control the solid state switch module to change between the open state and the closed state and to control the operating mechanism to open the separable contacts, a circuit breaker.

19. The electronic trip unit is configured to output the trip signal to the gate driver circuit and control the gate driver circuit to cause the solid state switch module to change to the open state, the circuit breaker according to claim 18.

20. The electronic trip unit is configured to control the operating mechanism to open the separable contacts only after the solid state switch module has changed to the open state, and the electronic trip unit is configured to control the gate driver circuit to change the solid state switch module to the closed state only after the separable contacts have been closed, the circuit breaker according to claim 18.

21. The solid state switch module interrupts the current flowing through the circuit breaker, and the separable contacts are configured to open to provide galvanic insulation between the power supply and the load, the circuit breaker according to claim 20.

22. A circuit breaker configured to electrically connect between a power supply and a load, a solid state switch module configured to have a closed state in which current can flow through the circuit breaker and an open state in which the current flowing through the circuit breaker is interrupted, a current sensor configured to detect a current flowing through the circuit breaker, An electronic trip unit configured to output a trip signal when detecting a fault condition based on the output of the current sensor; A gate driver circuit including an enable input electrically connected to the electronic trip unit and a desaturation (DESAT) input electrically connected to the solid state switch module, the gate driver circuit being configured to receive the trip signal at the enable input and execute a DESAT function based on a signal received at the DESAT input from the solid state switch module, the DESAT function monitoring a forward voltage drop of a solid state switch of the solid state switch module and controlling the state of the solid state switch module, the solid state switch module changing from an off state to an on state when a current flowing through the solid state switch module reaches a predetermined threshold level; the gate driver circuit; A separable contact; An operating mechanism configured to open and close the separable contact; A position sensor configured to detect the position of the separable contact, and including; The electronic trip unit is configured to control the solid state switch module to change between the open state and the closed state, and to control the operating mechanism to open the separable contact. Based on the output of the position sensor, the electronic trip unit is further configured to control the solid state switch module to change from the open state to the closed state when the separable contact is in the closed position. A circuit breaker.

23. The circuit breaker according to claim 22, wherein the electronic trip unit is configured to receive an output of the gate driver circuit indicating a state of the solid state switch module.

24. The circuit breaker according to claim 23, wherein the electronic trip unit is configured to ensure that the separable contact is opened only after the solid state switch module has changed to the open state, and that the solid state switch module changes to the closed state only after the separable contact has closed.

25. The circuit breaker according to claim 22, further including a closed switch and an open switch.

26. The electronic trip unit controls the operating mechanism to close the separable contact, and then outputs a closing signal to the gate driver circuit to change the solid state switch module in the gate driver circuit to the closed state in response to the operation of the closing switch, for the circuit breaker according to claim 25.

27. The electronic trip unit outputs the trip signal to the gate driver circuit to change the solid state switch module in the gate driver circuit to the open state, and then controls the operating mechanism to open the separable contact in response to the operation of the open button, for the circuit breaker according to claim 25.

28. A first position sensor configured to detect the operation of the closing switch, A second position sensor configured to detect the operation of the opening switch, further included in the circuit breaker according to claim 27.

29. The electronic trip unit receives the outputs of the first position sensor and the second position sensor, and is configured to detect the operations of the closing switch and the opening switch based on the outputs of the first position sensor and the second position sensor, for the circuit breaker according to claim 28.

30. The position sensor includes a microswitch actuated by the movement of a corresponding component, for the circuit breaker according to claim 22.

31. The position sensor is disposed by a movable arm of the operating mechanism, whereby the movement of the movable arm for opening and closing the separable contact actuates the position sensor, and based on the output of the position sensor, the electronic trip unit can detect the current position of the separable contact, for the circuit breaker according to claim 22.

32. The circuit breaker according to claim 22 further includes a power supply unit configured to receive power from the power source and convert the power from the power source into power usable by the components of the circuit breaker.

33. The power supply unit converts the alternating current power from the power source into direct current power usable by at least the electronic trip unit, the gate driver circuit, and the current sensor, for the circuit breaker according to claim 32.

34. The circuit breaker according to claim 32, wherein the electronic trip unit is configured to change the solid state switch module to the open state and open the separable contact when power is not available from the power supply unit or an external power supply unit.

35. The circuit breaker according to claim 32, wherein the power supply unit is configured to generate DC power used by components of the circuit breaker using the line voltage from the power source.

36. A circuit breaker configured to electrically connect a power source and a load, a solid state switch module configured to have a closed state in which current can flow through the circuit breaker and an open state in which the current flowing through the circuit breaker is interrupted; a current sensor configured to detect a current flowing through the circuit breaker; an electronic trip unit configured to output a trip signal when a fault state is detected based on an output of the current sensor; a gate driver circuit including an enable input electrically connected to the electronic trip unit and a desaturation (DESAT) input electrically connected to the solid state switch module, the gate driver circuit being configured to receive the trip signal at the enable input and execute a DESAT function based on a signal received at the DESAT input from the solid state switch module, the DESAT function including monitoring a forward voltage drop of a solid state switch of the solid state switch module and controlling a state of the solid state switch module by changing from an off state to an on state when a current flowing through the solid state switch module reaches a predetermined threshold level; a separable contact; and an operating mechanism configured to open and close the separable contact. The electronic trip unit is configured to control the solid state switch module to change between the open state and the closed state and to control the operating mechanism to open the separable contact. The electronic trip unit is further configured to output the trip signal based on the I-t trip curve, whereby the electronic trip unit outputs the trip signal to the gate driver circuit at a time related to a current level based on the I-t trip curve.

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