Contactor coil current stabilization during fault conditions

Abstract

A contactor system is disclosed that includes a first contactor including a first actuator coil configured to generate a magnetic hold force that maintains a moveable contact of the first contactor in a closed position. The system also includes a second contactor including a second actuator coil configured to generate a magnetic hold force that maintains a moveable contact of the second contactor in a closed position and a power source configured to energize the first actuator coil and the second actuator coil. The system includes a switch device configured to selectively establish a parallel connection between the first and second actuator coils and a series connection between the first and second actuator coils. The series connection causes inductance of the actuator coil of one of the contactors to counteract mutual inductance between a trip yoke and the actuator coil of the other contactor during a fault condition.

Description

CONTACTOR COIL CURRENT STABILIZATION DURING FAULT CONDITIONSFIELD OF THE TECHNOLOGY

[0001] The present disclosure relates generally to electromechanical switching devices, and more particularly to systems and methods for stabilizing actuator coil current in contactors during fault conditions.BACKGROUND

[0002] Electromechanical switching devices, such as contactors and relays, are commonly used in electrical systems to selectively connect and disconnect high-voltage circuits. For example, in electric vehicles, energy storage systems, and industrial power systems, contactors may be used to control the flow of current between a power source and a load. These devices typically include an actuator coil that generates a magnetic field when energized, causing movement of a plunger or armature that closes electrical contacts and completes a circuit.

[0003] In some implementations, contactors may include passive fault response mechanisms designed to interrupt current in response to fault conditions such as short circuits. For example, a contactor may include a ferromagnetic trip yoke configured to scavenge magnetic flux generated by fault current and redirect the flux into the actuator assembly to reduce magnetic hold force acting on the contactor mechanism. When the magnetic hold force is reduced below the opposing spring force, the contactor may open to interrupt the fault current.

[0004] During fault conditions, however, magnetic coupling between the trip yoke and the actuator coil can induce changes in the actuator coil current. Such induced current changes may increase or otherwise affect the magnetic hold force acting on the actuator assembly, which can slow the opening response of the contactor. In some systems, discrete inductive components may be added to the actuator coil drive circuit to resist rapid changes in coil current. However, incorporating additional inductive components may increase system cost, complexity, and space requirements.

[0005] Accordingly, there remains a need for improved systems and methods for stabilizing actuator coil current during fault conditions in contactor systems.SUMMARY

[0006] The following summary is meant to help one skilled in the art understand the various presently disclosed combinations of features. It is not meant to unduly limit the scope of any pending or future claims relating to the disclosure.

[0007] Contactor systems and methods for stabilizing actuator coil current during a fault condition are disclosed. In some embodiments, a contactor system includes a first contactor having a first actuator coil and a second contactor having a second actuator coil, along with a switch device configured to selectively establish parallel and series electrical connections between the actuator coils. During operation, the actuator coils may be connected in parallel to close the contactors and subsequently connected in series during a hold phase. When a fault condition occurs, inductance of the actuator coil of one contactor stabilizes current in the actuator coil of the other contactor through the series connection, counteracting mutual inductance between a trip yoke and the actuator coil of the fault-associated contactor.Stabilizing the actuator coil current allows a passive fault response mechanism to more effectively reduce magnetic hold force acting on the actuator assembly, enabling faster and more reliable opening of the contactor during a fault condition without requiring additional discrete inductive components.

[0008] In a particular embodiment, a contactor system is disclosed that includes a first contactor including a first actuator coil configured to generate a magnetic hold force that maintains a moveable contact of the first contactor in a closed position. The system also includes a second contactor including a second actuator coil configured to generate a magnetic hold force that maintains a moveable contact of the second contactor in a closed position. In addition, the system also includes a power source configured to energize the first actuator coil and the second actuator coil. The system also includes a switch device configured to selectively establish a parallel connection between the first actuator coil and the second actuator coil and a series connection between the first actuator coil and the second actuator coil. In this embodiment, the series connection causes inductance of the actuator coil of one of the contactors to counteract mutual inductance between a trip yoke and the actuator coil of the other contactor during a fault condition.

[0009] In another embodiment, a switch device is disclosed for controlling actuator coils of contactors. The switch device is configured to selectively establish a parallel connection between a first actuator coil of a first contactor and a second actuator coil of a second contactor and a series connection between the first actuator coil and the second actuator coil. In this embodiment, when the first actuator coil and the second actuator coil are connected in the series connection, inductance of the actuator coil of one of the contactors stabilizes coil current of the actuator coil of the other contactor during a fault condition associated with one of the contactors.

[0010] In another embodiment, a method of operating a contactor system is disclosed thatincludes energizing a first actuator coil of a first contactor to close the first contactor. The method also includes energizing a second actuator coil of a second contactor to close the second contactor. In addition, the method also includes after closing the first contactor and the second contactor, operating a switch device to place the first actuator coil and the second actuator coil in a series connection. The method also includes during a fault condition associated with one of the contactors, stabilizing current in the actuator coil of the one contactor using inductance of the actuator coil of the other contactor via the series connection to counteract mutual inductance between a trip yoke and the actuator coil of the one contactor.

[0011] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts of exemplary embodiments of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] One or more aspects of the present disclosure are discussed below with reference to the accompanying Figures. It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components may be included in one functional block or element.

[0013] Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. For purposes of clarity, however, not every component may be labeled in every drawing. The Figures are provided for the purposes of illustration and explanation and are not intended to be limiting. In the Figures:

[0014] FIG. 1 A is a diagram illustrating an isometric view of an example contactor with passive fault response according to at least one embodiment of the present disclosure.

[0015] FIG. IB is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure.

[0016] FIG. 1C is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure.

[0017] FIG. 2 is a block diagram illustrating an example contactor system according to at least one embodiment of the present disclosure.

[0018] FIG. 3 is a block diagram illustrating an example control system for the contactor system of FIG. 2 according to at least one embodiment of the present disclosure.

[0019] FIG. 4 is a flow chart of an example method of contactor coil current stabilization during a fault condition according to at least one embodiment of the present disclosure.

[0020] FIG. 5 is a flow chart illustrating an example method of operating a contactor system to stabilize actuator coil current during a fault condition according to at least one embodiment of the present disclosure.DETAILED DESCRIPTION

[0021] The terminology used herein for the purpose of describing particular examples is not intended to be limiting for further examples. Whenever a singular form such as “a”, "an" and “the” is used and using only a single element is neither explicitly or implicitly defined as being mandatory, further examples may also use plural elements to implement the same functionality. Likewise, when a functionality is subsequently described as being implemented using multiple elements, further examples may implement the same functionality using a single element or processing entity7. It will be further understood that the terms “comprises”, “comprising”, “includes” and / or “including”, when used, specify the presence of the stated features, integers, steps, operations, processes, acts, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, processes, acts, elements, components and / or any group thereof.

[0022] It will be understood that when an element is referred to as being “connected” or “coupled” to another element, the elements may be directly connected or coupled or via one or more intervening elements. If two elements A and B are combined using an “or”, this is to be understood to disclose all possible combinations, i.e., only A, only B, as well as A and B. An alternative wording for the same combinations is “at least one of A and B”. The same applies for combinations of more than two elements.

[0023] Accordingly, while further examples are capable of various modifications and alternative forms, some particular examples thereof are shown in the figures and will subsequently be described in detail. However, this detailed description does not limit further examples to the particular forms described. Further examples may cover all modifications, equivalents, and alternatives falling within the scope of the disclosure. Like numbers refer to like or similar elements throughout the description of the figures, which may be implemented identically or in modified form when compared to one another while providing for the same or a similar functionality'.

[0024] Contactors may be configured with passive fault response for passively interrupting a fault current in a high voltage circuit. In one example, an electrical contactor uses a unique "trip yoke" to scavenge flux from a high-voltage current and inject the flux into a magneticactuator circuit. This forces high reluctance in the actuator circuit causing a reduction in hold force on the actuator assembly. When the hold force is reduced below a force of an actuator assembly spring, the contactor opens and interrupts the fault without external control. In this example, the contactor routes all the actuator flux through a channel or "High-Way" in a predetermined direction. The trip yoke is placed over the high-way in a way to change the flux fields. The design is tuned by changing the thickness of the trip yoke and the width of the flux highway. This contactor design decouples the relationship of contact force to blowoff force, since the contacts are opened before the fault blow-off force equals the contact force (F=0). In the design it is desirable to maximize spring forces to rapid opening, minimum contact resistance and prevent current induced contact ringing.

[0025] For further explanation, FIG. 1 A is a diagram illustrating an isometric view of an example contactor with passive fault response according to at least one embodiment of the present disclosure. FIG. IB is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure. FIG. 1C is a diagram illustrating another view of the example contactor of FIG. 1A according to at least one embodiment of the present disclosure.

[0026] The contactor 100 of FIGs. 1A includes a moveable contact 106, an upper ferromagnetic trip yoke 105, a high voltage negative (HV -negative) terminal 102, aHV-positive terminal 104, a modified base plate 110 with a flux ferrous material ‘‘High-Way” 119 (shown in FIG. 1C), a single sided coil yoke and actuator circuit 115. and an actuator assembly enclosure 120.

[0027] The actuator assembly enclosure 120 houses and protects the components of the actuator assembly. Although not illustrated in FIG. 1A, the actuator assembly may include a plunger tube surrounding a plunger coupled to a plunger shaft, which is coupled to the moveable contact. In this example, a plunger spring may be coupled between the plunger and an upper coil yoke. The moveable contact 106 is configured to create or break the connection between the HV -negative terminal 102 and the HV-positive terminal 104 in response to movement of the actuator assembly. The HV contacts 102, 104 may be coupled to external connections for coupling with external components, such as a power supply and an electrical application.

[0028] In the open state, the moveable contact 106 is not in contact with the HV contacts 102, 104, such that no current flows between the HV contacts 102, 104. In this open state, the plunger spring is configured to apply a pre-load force on the plunger to prevent the actuator assembly from moving to a closed state. In the closed state, the moveable contact 106 is incontact with the HV contacts 102, 104 such that current flows between the HV contacts 102, 104 through the moveable contact 106.

[0029] A controller (not shown in FIG. 1 A) may be coupled to the single sided actuator circuit 115 and configured to control a current flowing to the circuit. When the circuit 115 is connected to a power source and current flows through the circuit, a strong magnetic field is generated that flows through the coil actuator magnetic circuit pathway of the contactor. This electromagnetic field is guided by ferromagnetic materials of the contactor and flows in a first direction through the actuator assembly. In a particular embodiment, this magnetic field is guided to the plunger, which resides within the enclosed plunger tube, and magnetizes it. The magnetized plunger is then attracted by a magnetic force to an upper flux tube. The magnetic field forces the plunger with upper direction. When enough magnetic force is generated, the plunger will overcome any retaining spring forces (pre-load force from the plunger spring) and begin to move. The plunger and the plunger shaft drive the moveable contact 106 toward the HV contacts 102, 104 until the moveable contact 106 is in a closed position in which contact is established between the moveable contact 106 and the HV contacts 102, 104, thus transitioning the contactor 100 from the open state to the closed state. When the moveable contact 106 touches the HV contacts 102, 104, the high-voltage circuit is closed. When the plunger contacts the upper flux tube, the magnetic circuit is closed.

[0030] When the actuator circuit 115 is disconnected from the low-voltage power source, the ferromagnetic components lose their magnetization and the magnetic force on the plunger decreases. This decrease in magnetic field separates the plunger from the upper flux tube, opening the magnetic circuit. The plunger spring returns the plunger to its original position. That is, when the circuit 115 is de-energized, the plunger is driven downward from the force of the energy stored in the compressed plunger spring, and the actuator assembly pulls the moveable contact 106 downward until the moveable contact 106 is in an open position, thus breaking the high voltage circuit betw een the moveable contact 106 and the HV contacts 102, 104.

[0031] The contactor 100 is also configured to passively detect and react to fault currents, eliminating the need for active monitoring systems. The trip yoke 105 scavenges magnetic flux from the fault current and redirects it into the actuator assembly, creating a trip yoke magnetic circuit that How s through the actuator assembly in a second direction that is opposite the first direction of the coil actuator magnetic circuit. The interactions of the trip yoke magnetic circuit and the coil actuator magnetic circuit flowing in opposite directions through the actuator assembly, reduces the magnetic hold force on the actuator assemblykeeping the moveable contact 106 closed. Once this hold force drops below the opposing force of the high-strength plunger spring, the plunger spring rapidly drives the moveable contact open, interrupting the fault current. This passive process occurs inherently within the system’s magnetic and mechanical structure, requiring no external control or intervention. In the example of FIG. IB, the contactor 100 also includes anon-ferrous sealing plate 121 coupled to the bottom of the base plate 110 to help direct the magnetic circuit through the high way 119. In addition, FIGS. 1B-1C include plates 116 on either side of the trip yoke 105.

[0032] A single contactor with passive fault response, when subjected to a fault current, will auto-open; however the fault will couple to the coil and to the trip yoke. This can cause a common mode positive coil current and trip yoke induction, slowing the trigger time. To address this, adding an inductor in series with the coil resists the change in coil current caused by mutual induction. This keeps the coil current steady and maximizes the effect of the trip yoke. However, the series inductor needs to approximately equal to the inductance of a contactor coil and it is not cost effective to add large inductors to the coil drive for each contactor.

[0033] In accordance with embodiments of the present disclosure, two contactors with passive fault response are utilized for the purpose of canceling short circuit mutual inductance, allowing quicker trigger in auto-opening contactors. In some examples, a controller is configured to command a first contact to close. The first contactor closes and enters the hold phase. The controller then commands a second contactor close. The second contactor closes and enters the hold phase. Via a switch, the first contactor’s coil is placed in series with the second contactor's. When the contactors are commanded to open, a clamp circuit is activated. In some examples, the first contactor is an HV+ and the second contactor is an HV- contactor. To cancel the mutual inductance, the coil of the first contactor must be in the opposite direction of the coil of the second contactors. This can be achieved, for example, by winding the coils clockwise / counterclockwise respectively or by winding both in the same direction but with inverse polarities.

[0034] Thus, an embodiment uses the available inductance from the HV- contractor to stabilize the coil current in the HV+ contactor by controlling them in series. In the event of a fault from HV+ to HV-, the HV+ contactor is the fault breaking contactor and HV- contactor is stabilizing the coil current in the HV+ contactor. In the event of a fault from HV- to HV+ the roles are reversed and the HV- contactor is the fault breaking contactor and the HV+ contactor is stabilizing the coil current in the HV- contactor.

[0035] Depending on the direction and location of a fault current in the high-voltage circuit, either contactor may act as the fault-interrupting contactor while the other contactor provides inductive stabilization of the actuator coil current. For example, when a fault occurs on a conductor associated with the first contactor, inductance of the actuator coil of the second contactor stabilizes the coil current of the first actuator coil. Conversely, when a fault occurs on a conductor associated with the second contactor, inductance of the actuator coil of the first contactor stabilizes the coil current of the second actuator coil.

[0036] For further explanation, FIG. 2 illustrates an example of a two-contactor configuration 200 in accordance with at least one embodiment of the present disclosure. For example, this two-contactor configuration 200 may be implemented in an electric vehicle. The configuration includes an HV battery 202. An HV+ terminal of the HV battery 202 is coupled to a first terminal of a first contactor 204 via an HV+ bus. A second terminal of the first contactor 204 is coupled to a load 206. Thus, the first contactor 204 may be referred to as the HV+ contactor. The first contactor 204 includes a first contactor coil 224 that, when energized, closes the first contactor 204. Thus, the first contactor coil 224 is configured to open and close the first contactor 204.

[0037] An HV- terminal of the HV battery 202 is coupled to a first terminal of a second contactor 208 via an HV- bus. A second terminal of the second contactor 208 is coupled to the load 206. Thus, the second contactor 208 may be referred to as the HV- contactor. The second contactor 208 includes a second contactor coil 228 that, when energized, closes the second contactor 208. Thus, the second contactor coil 228 is configured to open and close the second contactor 208. In some examples, the first contactor 204 and the second contactor 208 are auto-open contactors configured for passive fault response, as discussed above with reference to FIGS. 1A-1C.

[0038] The first contactor 204 includes a first contactor coil 224 that is selectively energized by a low voltage power source 210. The first contactor 204 receives commands to open and close from a control system 212. The second contactor 208 includes a second contactor coil 228 that is selectively energized by the low voltage power source 210. The second contactor 208 receives commands to open and close from the control system 212.

[0039] For further explanation, FIG. 3 illustrates an example control system 300 for a two-contactor configuration for canceling short circuit mutual inductance in accordance with at least one embodiment of the present disclosure. The control system 300 enables a quicker trigger in auto-opening contactors. The control system 300 includes a low voltage power source 210 that drive the first contactor coil 224 and the second contactor coil 228. Forexample, the first contactor coil 224 may be the contactor coil of a first auto-open passive fault contactor as discussed above. Likewise, the second contactor coil 228 may be the contactor coil of a second auto-open passive fault contactor as discussed above. The control system 300 includes a first controller 306 that controls the first contactor coil 224. For example, the first controller 306 may provide pulse width modulation (PWM) control of the first contactor coil 224. The first controller 306 may control the current supplied to the first contactor coil 224. The control system 300 also includes a second controller 310 that controls the second contactor coil 228. For example, the second controller 310 may provide PWM control for the second contactor coil 228. The second controller 310 may control the current supplied to the second contactor coil 228. In some examples, when the first contactor coil 224 and the second contactor coil 228 are operated in series, one controller 306, 310 (e.g., the first controller 306 in FIG. 3) operates to control both contactor coils 224, 228, thus controlling the current supplied to both contactor coils 224, 228 being operated in series. The system 300 also includes a clamp circuit 312 connected in parallel with the first contactor coil 224 and the second contactor coil 228. The clamp circuit 312 manages voltage transients that occur when the contactor coils are de-energized. These voltage spikes result from the sudden collapse of the magnetic field in the coil, which can generate high voltages that may damage circuit components or cause electrical noise.

[0040] In accordance with embodiments of the present disclosure, system 300 also includes a series / parallel switch 314. When switch 314 is in a first state, the first contactor coil 224 and the second contactor coil 228 are connected to the low voltage power source 210 in parallel. When switch 314 is in a second state, the first contactor coil 224 and the second contactor coil 228 are connected in series. Diodes 316, 318 may be employed to direct the flow of current in the system 300 and aid the function of the switch 314 in implementing the series / parallel connections. While the contactors 204, 208 are in the open state, the first contactor coil 224 and the second contactor coil 228 are connected in parallel and controlled separately. When the first contactor 204 and the second contactor 208 are in the closed state, switch 314 is controlled to connect the first contactor coil 224 and the second contactor coil 228 in series and clamp circuit 312 is activated. In one example, controller 306 takes over the control of current supplied to both contactor coils 224, 228 while the coils are operated in series. During a fault, the inductance of one contactor coil applied to the other contactor coil cancels the mutual inductance between the trip yoke and the contactor coil in the faulted contactor.

[0041] In some implementations, the actuator coils are connected in parallel during an initial closing operation so that each actuator coil receives sufficient voltage and current to reliably close its respective contactor. After the contactors are placed in the closed state, the coils may be reconfigured into a series connection for a hold phase of operation. During this hold phase, the combined inductance of the actuator coils increases the effective inductance of the coil drive circuit, which resists rapid changes in coil current and improves the stability of the actuator coil current during fault conditions.

[0042] For example, consider that a short circuit fault occurs in the first contactor 204.Although the first contactor 204 will auto-open, as discussed above, mutual inductance between the trip yoke (see FIG. 1A) and the first contactor coil will slow the opening time. To address this, the available inductance from the second contactor coil 228 is used to stabilize the coil current in the first contactor coil 224 by controlling them in series via switch 314. During a fault, inductance from the second contactor coil 228 keeps the coil current in the first contactor coil 224 steady and maximizes the effect of the trip yoke in the first contactor 204. This has the effect of canceling short circuit mutual inductance, allowing faster trigger in auto-opening contactors. To cancel the mutual inductance, the first contactor coil 224 should be in the opposite direction of the second contactor coil 228. This can be achieved, for example, by winding the coils clockwise / counterclockwise respectively or by winding both in the same direction but with inverse polarities.

[0043] Stabilization of the actuator coil current reduces a tendency for the actuator coil current to increase in response to magnetic coupling between the trip yoke and the actuator coil during a fault condition. By resisting rapid changes in actuator coil current, the inductive interaction between actuator coils connected in series helps maintain a predictable magnetic hold force and allows the passive fault response mechanism to respond more rapidly to the fault current.

[0044] Thus, the control system in accordance with the present disclosure allows for a passive trigger before a command is issued to open the contactor. The design is triggered by the fault currents, which gives redundancy to an active detection and trigger circuit. The design and control methods are inherently fault current limiting (contacts are open before peak amperage), reducing the potential for damage.

[0045] The switch device described herein may be implemented using various switching technologies including semiconductor switches, electromechanical switches, or combinations thereof. For example, the switch device may include one or more transistors, relays, diodes, or other switching components configured to selectively establish series and parallelelectrical connections between actuator coils. The switch device may also be implemented as part of a contactor driver circuit, power control module, or battery disconnect unit.

[0046] Although the examples described herein often reference electric vehicle applications, the systems and methods described may also be applied to other high-voltage switching environments including energy storage systems, industrial power distribution systems, renewable energy’ systems, and other applications involving high-current electromechanical switching devices.

[0047] For further explanation, FIG. 4 sets forth an example method of coil stabilization during a fault condition in accordance with the present disclosure. The method of FIG. 4 includes coupling 402 a load to a power source by closing a first contactor and a second contactor, wherein the first contactor is closed by energizing a first contactor coil and the second contactor is closed by energizing a second contactor coil. For example, the first contactor and the second contactor may be contactors configured for passive fault response to automatically open in response to a fault. As such, the first contactor and the second contactor may be contactors in accordance with FIGS. 1A-1C.

[0048] The method also includes operating 404 a switch to place the first contactor coil in series with the second contactor coil. For example, after the first contactor and the second contactor are closed, a hold current is applied to the first contactor coil and the second contactor coil. The first contactor coil and the second contactor coil are controlled in series. The first contactor coil and the second contactor coil are placed in series such that, in response to a fault in the first contactor coil, induction with the second contactor coil stabilizes the coil current in the first contactor coil via the series connection. The stabilization of the coil current in the first contactor coil enhances the performance of a trip yoke in the first contactor by counteracting mutual induction between the first contactor coil and the trip yoke, thus allowing for a faster opening of the first contactor.

[0049] Although some examples provided above are discussed in the context of an electric vehicle, it will be appreciated that coil stabilization during a fault condition in accordance with the present disclosure has applications outside of electric vehicles. For example, the techniques for coil stabilization during a fault condition may be employed in industrial applications, clean energy solutions, and so on.

[0050] For further explanation, FIG. 5 sets forth an example method of coil stabilization during a fault condition in accordance with the present disclosure.

[0051] The method of FIG. 5 includes energizing 502 a first actuator coil of a first contactor to close the first contactor. Energizing 502 the first actuator coil of the first contactor to closethe first contactor may be carried out by applying electrical power from a low-voltage power source to the first actuator coil. In some embodiments, a controller may command the application of current to the first actuator coil through a driver circuit or switching device that regulates the current supplied to the coil. The current flowing through the first actuator coil generates a magnetic field that produces a magnetic hold force within the actuator assembly, causing movement of a plunger and associated moveable contact toward a closed position. When sufficient magnetic force is generated to overcome a spring force of the actuator assembly, the moveable contact engages corresponding terminals of the contactor to close the high-voltage circuit.

[0052] In addition, the method of FIG. 5 includes energizing 504 a second actuator coil of a second contactor to close the second contactor. Energizing 504 the second actuator coil of the second contactor to close the second contactor may be carried out by supplying electrical power from the low-voltage power source to the second actuator coil. In some embodiments, a controller may command a driver circuit or switching device to deliver current to the second actuator coil in response to a control signal. Current flowing through the second actuator coil generates a magnetic field that produces a magnetic hold force within the actuator assembly of the second contactor, causing a plunger and associated moveable contact to move toward a closed position. When the magnetic force generated by the energized second actuator coil exceeds a spring force of the actuator assembly, the moveable contact engages corresponding terminals of the second contactor to close the high-voltage circuit.

[0053] The method of FIG. 5 includes after closing the first contactor and the second contactor, operating 506 a switch device to place the first actuator coil and the second actuator coil in a series connection. In some embodiments, a controller may command the switch device to reconfigure electrical connections between the actuator coils such that current supplied by the low-voltage power source flows sequentially through the first actuator coil and the second actuator coil. The switch device may include one or more semiconductor switches, relays, diodes, or other switching components configured to selectively establish the series connection between the actuator coils. By connecting the actuator coils in series during a hold phase of operation, the combined inductance of the actuator coils increases the effective inductance of the coil drive circuit.

[0054] In addition, the method of FIG. 5 includes during a fault condition associated with one of the contactors, stabilizing 508 current in the actuator coil of the one contactor using inductance of the actuator coil of the other contactor via the series connection to counteractmutual inductance between a trip yoke and the actuator coil of the one contactor. In some embodiments, a fault current flowing through the high-voltage circuit generates magnetic flux that is scavenged by a trip yoke and coupled into the actuator assembly of the fault-associated contactor. Magnetic coupling between the trip yoke and the actuator coil can induce a change in the coil current of the fault-associated contactor. The series connection between the actuator coils provides additional inductance that resists the change in coil current, thereby stabilizing the actuator coil current and enabling the passive fault response mechanism to more rapidly open the contactor.

[0055] The method of FIG. 5 improves the ability of the contactor system to respond to fault conditions by stabilizing actuator coil current during a fault event. By placing the actuator coils of multiple contactors in a series connection after the contactors are closed, the inductance of one actuator coil is used to resist rapid changes in current induced by magnetic coupling between a trip yoke and the actuator coil of the fault-associated contactor.Stabilizing the actuator coil current allows the passive fault response mechanism to more effectively reduce the magnetic hold force acting on the actuator assembly, enabling faster and more reliable opening of the contactor during a fault condition. As a result, the method can improve fault interruption performance while avoiding the need for additional discrete inductive components in the coil drive circuit.

[0056] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, apparatuses, and methods, according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

[0057] Advantages and features of the present disclosure can be further described by the following statements:

[0058] 1. A contactor system comprising: a first contactor including a first actuator coil configured to generate a magnetic hold force that maintains a moveable contact of the first contactor in a closed position; a second contactor including a second actuator coil configured to generate a magnetic hold force that maintains a moveable contact of the second contactor in a closed position; a power source configured to energize the first actuator coil and thesecond actuator coil; and a switch device configured to selectively establish: a parallel connection between the first actuator coil and the second actuator coil; and a series connection between the first actuator coil and the second actuator coil, wherein the series connection causes inductance of the actuator coil of one of the contactors to counteract mutual inductance between a trip yoke and the actuator coil of the other contactor during a fault condition.

[0059] 2. The contactor system of statement 1, wherein, when connected in series, the first actuator coil stabilizes a coil current in the second actuator coil during a fault condition associated with the second contactor.

[0060] 3. The contactor system of statement 1 or 2, wherein the switch device is operated to connect the first actuator coil and the second actuator coil in series after the first contactor and the second contactor are placed in a closed state.

[0061] 4. The contactor system of any of statements 1-3, wherein a coil current of the first actuator coil is stabilized by induction from the second actuator coil.

[0062] 5. The contactor system of any of statements 1-4, wherein at least one of the first contactor or the second contactor comprises a passive fault response mechanism including: a moveable contact configured to physically connect and disconnect a high-voltage circuit between a high-voltage negative terminal and a high-voltage positive terminal; an actuator assembly configured to maintain the moveable contact in a closed position in response to a magnetic hold force generated by the respective actuator coil; a ferromagnetic trip yoke positioned to scavenge magnetic flux from the high-voltage circuit and redirect the flux into the actuator assembly, wherein the trip yoke increases magnetic reluctance in the actuator assembly during the fault condition to reduce the magnetic hold force on the actuator assembly; and a spring mechanism configured to open the moveable contact when the magnetic hold force decreases below a spring force.

[0063] 6. The contactor system of any of statements 1-5, wherein inductance of the actuator coil of one of the contactors stabilizes current in the actuator coil of the other contactor to counteract mutual inductance between the trip yoke and the actuator coil of the other contactor during the fault condition.

[0064] 7. The contactor system of any of statements 1-6, wherein the passive fault response mechanism operates without requiring external sensors, controllers, or electronic monitoring systems such that detection and interruption of the fault current is achieved through interaction of the trip yoke, a flux high-way, and the actuator coil.

[0065] 8. The contactor system of any of statements 1-7, wherein the series connectionstabilizes coil current of the actuator coil of one of the contactors by resisting a change in the coil current induced by magnetic coupling between a trip yoke and the actuator coil of that contactor during the fault condition.

[0066] 9. The contactor system of any of statements 1-8, wherein stabilizing the coil current increases the speed at which the moveable contact of one of the contactors opens relative to operation without the series connection.

[0067] 10. The contactor system of any of statements 1-9, wherein the first actuator coil is wound in an opposite direction relative to the second actuator coil.

[0068] 11. The contactor system of any of statements 1-10, wherein the first actuator coil and the second actuator coil are wound in a same direction and connected with opposite polarity.

[0069] 12. The contactor system of any of statements 1-11, further comprising a clamp circuit configured to limit a voltage transient when the first actuator coil and the second actuator coil are de-energized.

[0070] 13. The contactor system of any of statements 1-12, wherein the first contactor is coupled between a positive terminal of a battery and a load and the second contactor is coupled between a negative terminal of the battery and the load.

[0071] 14. A switch device for controlling actuator coils of contactors, the switch device configured to selectively establish: a parallel connection between a first actuator coil of a first contactor and a second actuator coil of a second contactor; and a series connection between the first actuator coil and the second actuator coil; wherein, when the first actuator coil and the second actuator coil are connected in the series connection, inductance of the actuator coil of one of the contactors stabilizes coil current of the actuator coil of the other contactor during a fault condition associated with one of the contactors.

[0072] 15. The switch device of statement 14. wherein the switch device is configured to connect the actuator coils in parallel during a closing operation of the contactors and to connect the actuator coils in series during a hold operation of the contactors.

[0073] 16. The switch device of statement 14 or 15, further comprising a controller configured to control current supplied to the first actuator coil and the second actuator coil.

[0074] 17. The switch device of any of statements 14-16, wherein the controller is configured to control current through both actuator coils when the actuator coils are connected in the series connection.

[0075] 18. The switch device of any of statements 14-17, further comprising a clamp circuit configured to limit a voltage transient when the actuator coils are de-energized.

[0076] 19. The switch device of any of statements 14-18, further comprising at least onediode configured to direct current flow to implement the parallel connection and the series connection.

[0077] 20. A method of operating a contactor system, the method comprising: energizing a first actuator coil of a first contactor to close the first contactor; energizing a second actuator coil of a second contactor to close the second contactor; after closing the first contactor and the second contactor, operating a switch device to place the first actuator coil and the second actuator coil in a series connection; and during a fault condition associated with one of the contactors, stabilizing current in the actuator coil of the one contactor using inductance of the actuator coil of the other contactor via the series connection to counteract mutual inductance between a trip yoke and the actuator coil of the one contactor.

[0078] It will be understood from the foregoing description that modifications and changes may be made in various embodiments of the present disclosure without departing from its true spirit. The descriptions in this specification are for purposes of illustration only and are not to be construed in a limiting sense. The scope of the present disclosure is limited only by the language of the following claims.

Claims

CLAIMSWhat is claimed is:

1. A contactor system comprising:a first contactor including a first actuator coil configured to generate a magnetic hold force that maintains a moveable contact of the first contactor in a closed position; a second contactor including a second actuator coil configured to generate a magnetic hold force that maintains a moveable contact of the second contactor in a closed position;a power source configured to energize the first actuator coil and the second actuator coil; anda switch device configured to selectively establish:a parallel connection between the first actuator coil and the second actuator coil; and a series connection between the first actuator coil and the second actuator coil, wherein the series connection causes inductance of the actuator coil of one of the contactors to counteract mutual inductance between a trip yoke and the actuator coil of the other contactor during a fault condition.

2. The contactor system of claim 1, wherein, when connected in series, the first actuator coil stabilizes a coil current in the second actuator coil during a fault condition associated with the second contactor.

3. The contactor system of claim 1. wherein the switch device is operated to connect the first actuator coil and the second actuator coil in series after the first contactor and the second contactor are placed in a closed state.

4. The contactor system of claim 1, wherein a coil current of the first actuator coil is stabilized by induction from the second actuator coil.

5. The contactor system of claim 1, wherein at least one of the first contactor or the second contactor comprises a passive fault response mechanism including:a moveable contact configured to physically connect and disconnect a high-voltage circuit between a high-voltage negative terminal and a high-voltage positive terminal; an actuator assembly configured to maintain the moveable contact in a closed position in response to a magnetic hold force generated by the respective actuator coil;a ferromagnetic trip yoke positioned to scavenge magnetic flux from the high-voltage circuit and redirect the flux into the actuator assembly, wherein the trip yoke increases magnetic reluctance in the actuator assembly during the fault condition to reduce the magnetic hold force on the actuator assembly; anda spring mechanism configured to open the moveable contact when the magnetic hold force decreases below a spring force.

6. The contactor system of claim 5, wherein inductance of the actuator coil of one of the contactors stabilizes current in the actuator coil of the other contactor to counteract mutual inductance between the trip yoke and the actuator coil of the other contactor during the fault condition.

7. The contactor system of claim 5. wherein the passive fault response mechanism operates without requiring external sensors, controllers, or electronic monitoring systems such that detection and interruption of a fault current is achieved through interaction of the trip yoke, a flux high-way, and the actuator coil.

8. The contactor system of claim 5. wherein the series connection stabilizes coil current of the actuator coil of one of the contactors by resisting a change in the coil current induced by magnetic coupling between a trip yoke and the actuator coil of that contactor during the fault condition.

9. The contactor system of claim 8. wherein stabilizing the coil current increases the speed at which the moveable contact of one of the contactors opens relative to operation without the series connection.

10. The contactor system of claim 1, wherein the first actuator coil is wound in an opposite direction relative to the second actuator coil.

11. The contactor system of claim 1. wherein the first actuator coil and the second actuator coil are wound in a same direction and connected with opposite polarity.

12. The contactor system of claim 1, further comprising a clamp circuit configured to limit a voltage transient when the first actuator coil and the second actuator coil are de-energized.

13. The contactor system of claim 1, wherein the first contactor is coupled between a positive terminal of a battery and a load and the second contactor is coupled between a negative terminal of the battery and the load.

14. A switch device for controlling actuator coils of contactors, the switch device configured to selectively establish:a parallel connection between a first actuator coil of a first contactor and a second actuator coil of a second contactor; anda series connection between the first actuator coil and the second actuator coil; wherein, when the first actuator coil and the second actuator coil are connected in the series connection, inductance of the actuator coil of one of the contactors stabilizescoil current of the actuator coil of the other contactor during a fault condition associated with one of the contactors.

15. The switch device of claim 14, wherein the sw itch device is configured to connect the actuator coils in parallel during a closing operation of the contactors and to connect the actuator coils in series during a hold operation of the contactors.

16. The switch device of claim 14. further comprising a controller configured to control current supplied to the first actuator coil and the second actuator coil.

17. The switch device of claim 16, wherein the controller is configured to control current through both actuator coils when the actuator coils are connected in the series connection.

18. The switch device of claim 14. further comprising a clamp circuit configured to limit a voltage transient when the actuator coils are de-energized.

19. The switch device of claim 14, further comprising at least one diode configured to direct current flow to implement the parallel connection and the series connection.

20. A method of operating a contactor system, the method comprising:energizing a first actuator coil of a first contactor to close the first contactor; energizing a second actuator coil of a second contactor to close the second contactor; after closing the first contactor and the second contactor, operating a switch device to place the first actuator coil and the second actuator coil in a series connection; and during a fault condition associated with one of the contactors, stabilizing current in the actuator coil of the one contactor using inductance of the actuator coil of the other contactor via the series connection to counteract mutual inductance between a trip yoke and the actuator coil of the one contactor.

Images