Patent Description:
<CIT> discloses a solenoid driver capable of detecting the operational status of a solenoid including the position of an armature within a solenoid coil, based on measuring current decay times.

Methods and apparatuses for failure mode detection in a contactor are disclosed. As will be explained below, a contactor according to embodiments of the present invention includes a plunger and a coil. The coil may be configured to be energized with a current or a voltage. In particular embodiments, the contactor is configured to move the plunger in response to a change in state of a contactor command signal. The contactor command signal may have a plurality of states including a first state and a second state. The first state of the contactor command signal directs the plunger to move to an open position that places the contactor in an open state in which the contactor does not connect a first connector and a second connector. The second state of the contactor command signal directs the plunger to move to a closed position that places the contactor in a closed state in which the contactor does connect the first connector and the second connector.

In a particular embodiment, a method for failure mode detection in a contactor includes determining whether the contactor is welded closed. To make this determination, the method includes a detection controller maintaining the contactor command signal in the open state and connecting the contactor to a voltage supply that supplies a first predetermined voltage amount to the contactor. The detection controller measures a first amount of time for a magnitude of a coil current of the coil to exceed a first predetermined current threshold. In this embodiment, the detection controller determines whether the first amount of time exceeds a first predetermined time threshold. Responsive to determining that the first amount of time does not exceed the first predetermined time threshold, the detection controller determines that the contactor is in the open state, which indicates that the contactor is not welded closed. However, responsive to determining that the first amount of time exceeds the first predetermined time threshold, the detection controller may determine that the contactor is in the closed state, which provides an indication that the contactor is welded closed.

In another embodiment of the present invention, a method for failure mode detection in a contractor includes determining whether the plunger of the contactor is stuck. To make this determination, the method includes a detection controller switching the contactor command signal from the open state into the closed state. Switching the contactor command signal to the closed state directs the plunger to move into the closed position, which places the contactor in the closed state. In this embodiment, the detection controller connects the contactor to a voltage supply that supplies a first voltage amount to the contactor. After applying the first voltage amount to the contactor, the detection controller determines changes in a magnitude of a coil current of the coil over a period of time. The detection controller determines whether the determined changes of the coil current over the period of time are associated with a pattern that indicates the plunger moved from the open position to the closed position. Responsive to determining that the determined changes are associated with the pattern, the detection controller may make a first determination that the plunger is not stuck. However, responsive to determining that the determined changes are not associated with the pattern, the detection controller may determine that the plunger is stuck.

In another embodiment of the present invention, a method for failure mode detection in a contactor includes determining whether a plunger of the contactor unexpectedly moves during monitoring, which may indicate a mechanical shock to the contactor. To make this determination, the method includes a detection controller lowering the coil current to a hold current threshold and maintaining the contactor at an efficient power level. In this embodiment, the detection controller monitors a magnitude of the coil current of the coil and determines whether the magnitude of the coil current changed within a first predetermined time period by at least a first predetermined amount. Responsive to determining that the magnitude of the coil current changed within the first predetermined time period by at least the first predetermined amount, the detection controller may determine that the plunger has unexpectedly moved despite the contactor command signal not changing states.

As will be explained below, a detection controller that detects fault modes (e.g., whether a contactor is welded closed, whether a plunger is stuck, or whether a plunger expectedly moves) may be used to improve the safety and reliability of a contactor. 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.

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. 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.

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.

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.

Exemplary methods, apparatuses, devices, and computer program products for failure mode detection in a contactor in accordance with the present disclosure are described with reference to the accompanying drawings, beginning with <FIG>. For further explanation, <FIG> sets forth a diagram of a contactor <NUM> that includes a plunger <NUM>, a coil <NUM>, a top shield <NUM>, a flux tube <NUM>, and a cup <NUM>.

In the example of <FIG>, the coil <NUM> may be configured to be energized with a current or a voltage. The contactor <NUM> may be configured to move the plunger <NUM> in response to a change in state of a contactor command signal. The contactor command signal may have a plurality of states including a first state and a second state. The first state of the contactor command signal directs the plunger <NUM> to move to an open position that places the contactor <NUM> in an open state in which the contactor <NUM> does not connect a first connector (not shown) and a second connector (not shown). The second state of the contactor command signal directs the plunger <NUM> to move to a closed position that places the contactor <NUM> in a closed state in which the contactor <NUM> does connect the first connector and the second connector.

As explained above, the contactor may become welded closed, the plunger may become stuck, or the plunger may unexpectedly move. During these fault modes, the current through the coil (coil current signal) changes. See for example <FIG>, which illustrates three coil current signals that are caused by the movement of the plungers during closing of the contactor when the contactor is welded closed; when the plunger is stuck; and when the plunger is free to move. As will be explained below, a detection controller may determine this change in the coil current and use the determination of changes to the coil current to detect the fault modes of the contactor.

For further explanation, <FIG> illustrates an example of a detection controller according to at least one embodiment of the present disclosure. In the example of <FIG>, the detection controller <NUM> uses a microprocessor and peripheral components to detect changes to coil current or voltage within a contactor.

The detection controller <NUM> may use the detection of the changes within the contactor to detect and diagnose fault modes of the contactor. For example, <FIG> illustrates the shape of the coil currents that are used to detect a first fault mode in which the contactor is welded closed, a second fault mode in which the plunger is stuck (did not fully close), and a third fault mode in which the plunger unexpectedly moves.

In a particular embodiment, the detection controller may be integrated in a custom integrated circuit that includes circuitry which economizes the power of the coil between various phases and can further include voltage suppression diodes such that a printed circuit board can be replaced with a single chip that includes the detection controller. In another embodiment, the single chip could be packaged in a custom package with custom lead frame that includes a method to allow easy, robust and cheap mounting in the contactor assembly such as press-fit connections or welding of coil wires to the package directly.

For further explanation, <FIG> sets forth a flow chart illustrating an exemplary method of failure mode detection in a contactor according to embodiments of the present disclosure. According to embodiments of the present invention, the contactor (e.g., the contactor <NUM> of <FIG>) includes a plunger (e.g., the plunger <NUM> of <FIG>. ) and a coil (e.g., the coil <NUM> of <FIG>). The coil may be configured to be energized with a current or a voltage. In this example, the contactor is configured to move the plunger in response to a change in state of a contactor command signal. The contactor command signal may have a plurality of states including a first state and a second state. In the example of <FIG>, the first state of the contactor command signal directs the plunger to move to an open position that places the contactor in an open state in which the contactor does not connect a first connector and a second connector. The second state of the contactor command signal directs the plunger to move to a closed position that places the contactor in a closed state in which the contactor does connect the first connector and the second connector.

As explained above, a contactor may experience one or more fault modes that prevent the contactor from connecting or disconnecting with connectors in accordance with the contactor command signal. An example of one such fault mode is when the contactor command signal is in the open state but the contactor is not fully opened since the last state, which indicates that the contactor is welded closed. A detection controller <NUM> in the method of <FIG> may be used to identify whether the contactor is in this fault mode by determining whether the contactor is closed despite the contactor command signal being in the open state. The detection controller <NUM> may be an example of the detection controller <NUM> of <FIG>. In a particular embodiment, the detection controller may include computer program instructions that when executed cause the detection controller to perform fault mode detection in accordance with one or more embodiments of the present invention.

To make this determination, the method of <FIG> begins by maintaining <NUM> the contactor command signal in the open state. Maintaining <NUM> the contactor command signal in the open state may be carried out by continuing to supply a particular signal associated with the open state to the contactor. Alternatively, maintaining <NUM> the contactor command signal in the open state may be carried out by providing no signal. In this embodiment, providing no signal may indicate to the contactor the contactor command signal is in the open state.

The method of <FIG> also includes connecting <NUM> the contactor to a voltage supply that supplies a first predetermined voltage amount to the contactor. As explained above, a voltage supply may be used to energize the contactor. Connecting <NUM> the contactor to a voltage supply that supplies a first predetermined voltage amount to the contactor may be carried out by coupling the voltage supply to the contactor.

In addition, the method of <FIG> includes measuring <NUM> a first amount of time for a magnitude of a coil current of the coil to exceed a first predetermined current threshold. In a particular embodiment, the first predetermined current threshold is a current level sufficiently low to keep the plunger from moving. Measuring <NUM> a first amount of time for a magnitude of a coil current of the coil to exceed a first predetermined current threshold may be carried out by incrementing a counter to correspond to a passage of time; monitoring a coil current of the coil; determining whether the coil current exceeds the first predetermined current threshold; and continuing to increment the counter responsive to a determination that the coil current does not exceed the first predetermined current threshold.

The method of <FIG> includes determining <NUM> whether the first amount of time exceeds a first predetermined time threshold. The first predetermined time threshold may correspond with a maximum amount of time in which the inductance of the contactor would remain low, indicating that the contactor is open or not welded. Determining <NUM> whether the first amount of time exceeds a first predetermined time threshold may be carried out by comparing the first amount of time to the first predetermined time threshold.

The method of <FIG> also includes responsive to determining that the first amount of time exceeds the first predetermined time threshold, determining <NUM> that the contactor is in the closed state. Determining <NUM> that the contactor is in the closed state responsive to determining that the first amount of time exceeds the first predetermined time threshold may be carried out by transmitting a signal indicating that a fault has occurred or that a specific fault mode has occurred; setting or storing a flag or value that confirms the contactor is in the wrong state (closed state) or that a fault has occurred.

In addition, the method of <FIG> includes responsive to determining that the first amount of time does not exceed the first predetermined time threshold, determining <NUM> that the contactor is in the open state. Determining <NUM> that the contactor is in the open state responsive to determining that the first amount of time does not exceed the first predetermined time threshold may be carried out by storing an indication or flag confirming that the contactor is in the correct state (open state); or sending a signal confirming that the contactor is in the correct state.

For further explanation, <FIG> sets forth a flow chart illustrating an exemplary method of failure mode detection in a contactor according to embodiments of the present disclosure. The method of <FIG> is similar to the method of <FIG> in that the method of <FIG> includes all of the elements of <FIG>.

As explained above, a contactor may experience one or more fault modes that prevent the contactor from connecting or disconnecting in accordance with the contactor command signal. Another example of one such fault mode is when the contactor command signal is in the closed state and the contactor's previous state was the open state, but the contactor is not fully closed. One reason that a contactor might not switch to the closed state is that the plunger is stuck. The method of <FIG> includes steps for identifying this particular fault mode by determining whether the plunger is stuck.

To make this determination, the method of <FIG> begins by switching <NUM> the contactor command signal into the closed state that directs the plunger to move into the closed position that places the contactor in the closed state. Switching <NUM> the contactor command signal into the closed state that directs the plunger to move into the closed position that places the contactor in the closed state may be carried out by changing the magnitude or frequency of the contactor command signal to indicate the closed state; and applying that changed signal to the contactor.

The method of <FIG> also includes connecting <NUM> the contactor to the voltage supply that supplies a second voltage amount to the contactor. Connecting <NUM> the contactor to the voltage supply that supplies a second voltage amount to the contactor may be carried out by coupling the voltage supply to the contactor. The second voltage amount may be equal to the voltage amount in <FIG>.

In addition, the method of <FIG> also includes after applying the second voltage amount to the contactor, determining <NUM> changes in the magnitude of the coil current of the coil over a period of time. Determining <NUM> changes in the magnitude of the coil current of the coil over a period of time may be carried out by incrementing a counter that tracks an amount of time, determining whether the amount of time exceeds a threshold; measuring the coil current; and storing measurements of the coil current at different time intervals.

The method of <FIG> also includes determining <NUM> whether the determined changes of the coil current over the period of time are associated with a pattern that indicates the plunger moved from the open position to the closed position. Determining <NUM> whether the determined changes of the coil current over the period of time are associated with a pattern that indicates the plunger moved from the open position to the closed position may be carried out by retrieving one or more patterns that each indicate a magnitude of a coil current at different time intervals for a period of time; and comparing the determined changes in the coil current at different time intervals to one or more of the patterns. In a particular embodiment, the one or more patterns may be stored in a memory or storage location accessible by the detection controller <NUM>.

The method of <FIG> includes responsive to determining that the determined changes are not associated with the pattern, determining <NUM> that the plunger is stuck. Determining <NUM> that the plunger is stuck may be carried out by transmitting a signal indicating that a fault has occurred or that a specific fault mode has occurred; and setting or storing a flag or value that confirms the plunger is stuck or that a fault has occurred. In a particular embodiment, the process for determining a fault is determined once a fault has been detected.

The method of <FIG> also includes responsive to determining that the determined changes are associated with the pattern, making <NUM> a first determination that the plunger is not stuck. Making <NUM> a first determination that the plunger is not stuck may be carried out by storing an indication or flag confirming that the plunger is not stuck; or sending a signal confirming that the plunger is not stuck.

The method of <FIG> provides further steps for determining whether a plunger is stuck. Specifically, the method of <FIG> includes determining <NUM> that the magnitude of the coil current has stabilized. Determining <NUM> that the magnitude of the coil current has stabilized may be carried out by monitoring the coil current; measuring samples of the magnitude of the coil current; comparing the samples to each other to determine an amount of deviation; and determining whether the amount of deviation exceeds a threshold.

The method of <FIG> also includes after determining that the magnitude of the coil current has stabilized, stopping <NUM> supply of voltage to the coil. Stopping <NUM> supply of voltage to the coil may be carried out by disconnecting the voltage supply from the coil.

In addition, the method of <FIG> also includes after stopping the supply of voltage to the coil, determining <NUM> a second amount of time for the magnitude of the coil current to drop below a second current threshold. Determining <NUM> a second amount of time for the magnitude of the coil current to drop below a second current threshold may be carried out by incrementing a counter to correspond to a passage of time; monitoring a coil current of the coil; determining whether the coil current drops below the second predetermined current threshold; and continuing to increment the counter responsive to a determination that the coil current does not drop below the second predetermined current threshold. For example, if the second amount of time is below the second predetermined time threshold, the inductance of the coil may be assumed to be below a certain threshold and the magnetic system is saturated, which indicates that the contactor is fully closed and the plunger is not stuck in the open position.

The method of <FIG> also includes determining <NUM> whether the second amount of time does not exceed a second predetermined time threshold. Determining <NUM> whether the second amount of time does not exceed a second predetermined time threshold may be carried out by comparing the second amount of time to the second predetermined time threshold.

The method of <FIG> includes responsive to determining that the second amount of time does exceed the second predetermined time threshold, determining <NUM> that the plunger is stuck in the open position. Determining <NUM> that the plunger is stuck may be carried out by transmitting a signal indicating that a fault has occurred or that a specific fault mode has occurred; setting or storing a flag or value that confirms the plunger is stuck or that a fault has occurred.

The method of <FIG> continues by responsive to determining that the second amount of time does not exceed the second predetermined time threshold, making <NUM> a second determination that the plunger is not stuck. Making <NUM> a second determination that the plunger is not stuck may be carried out by storing an indication or flag confirming that the plunger is not stuck; or sending a signal confirming that the plunger is not stuck.

After using the method of <FIG> to determine whether the plunger is stuck, the method of <FIG> may be used to determine whether the contactor is experiencing another fault mode in which the plunger is unexpectantly moving (e.g., due to mechanical shock). In this example embodiment, the contactor command signal is in the closed state and the contactor's previous state was the closed state.

After making the first determination and the second determination that the plunger is not stuck in <FIG>, the method of <FIG> begins by lowering <NUM> the coil current to a hold current. Lowering <NUM> the coil current to a hold current may be carried out by changing the voltage or current applied to the contactor; measuring the magnitude of the coil current; and comparing the measured magnitude of the coil current to the hold current setpoint. The hold current setpoint may be selected to maintain the contactor at an efficient power level.

The method of <FIG> also includes maintaining <NUM> the contactor at an efficient power level. Maintaining <NUM> the contactor at an efficient power level may be carried out by adjusting the drive voltage to the coil using pulse width modulation "PWM".

In addition, the method of <FIG> includes monitoring <NUM> a magnitude of the coil current of the coil. Monitoring <NUM> a magnitude of the coil current of the coil may be carried out by continuously or periodically measuring the magnitude of the coil current.

The method of <FIG> also includes determining <NUM> whether the magnitude of the coil current changed within a first predetermined time period by at least a first predetermined amount. Determining <NUM> whether the magnitude of the coil current changed within a first predetermined time period by at least a first predetermined amount may be carried out by incrementing a counter to correspond to a passage of time; determining whether the counter indicates an amount that exceeds the predetermined time period; determining an amount of change or deviation in the coil current while the counter indicates an amount that does not exceed the predetermined time period; and determining whether the amount of change or deviation exceeds the first predetermined amount.

The method of <FIG> includes responsive to determining that the magnitude of the coil current changed within the first predetermined time period by at least the first predetermined amount, determining <NUM> that the plunger has moved despite the contactor command signal not changing states. Determining <NUM> that the plunger has moved despite the contactor command signal not changing states may be carried out by transmitting a signal indicating that a fault has occurred or that a specific fault mode has occurred; setting or storing a flag or value that confirms the plunger unexpectedly moved or that a fault has occurred.

After determining in <FIG> that the plunger unexpectedly moved, the method of <FIG> may be used to attempt to open the contactor to avoid welding due to restrike. The method of <FIG> includes switching <NUM> the contactor command signal to the open state. Switching <NUM> the contactor command signal to the open state may be carried out by changing the magnitude or frequency of the contactor command signal to indicate the open state; and applying that changed signal to the contactor.

The method of <FIG> also includes setting <NUM> the coil drive voltage to zero. Setting <NUM> the coil drive voltage to zero may be carried out by lowering the coil drive voltage.

The method of <FIG> also includes after switching the contactor command signal to the open state and setting the coil drive voltage to zero, measuring <NUM> a third amount of time. Measuring <NUM> a third amount of time may be carried out by incrementing a counter to correspond to a passage of time.

In addition, the method of <FIG> also includes determining <NUM> whether the fourth amount of time exceeds a fourth predetermined time threshold and the coil current is reduced to zero. Determining <NUM> whether the third amount of time exceeds a third predetermined time threshold and the coil current is reduced to zero may be carried out by monitoring a coil current of the coil; determining whether the coil current is reduced to zero; continuing to increment the counter responsive to a determination that the coil current is not reduced to zero; and comparing the counter to the third predetermined time threshold.

For further explanation, <FIG> sets forth a flow chart illustrating an exemplary method of failure mode detection in a contactor according to embodiments of the present disclosure. The method of <FIG> is similar to the method of <FIG> in that the method of <FIG> includes all of the elements of <FIG>. However, the method of <FIG> includes additional elements for determining whether the contactor is welded closed. The method of <FIG> includes connecting <NUM> the contactor to the voltage supply that supplies the third predetermined voltage amount to the contactor. Connecting <NUM> the contactor to the voltage supply that supplies the third predetermined voltage amount to the contactor may be carried out by coupling the voltage supply to the contactor.

The method of <FIG> also includes measuring <NUM> a fourth amount of time for the magnitude of the coil current of the coil to exceed a third predetermined current threshold. Measuring <NUM> a fourth amount of time for the magnitude of the coil current of the coil to exceed a third predetermined current threshold may be carried out by incrementing a counter to correspond to a passage of time; monitoring a coil current of the coil; determining whether the coil current exceeds the fourth predetermined current threshold; and continuing to increment the counter responsive to a determination that the coil current does not exceed the fourth predetermined current threshold.

In addition, the method of <FIG> includes determining <NUM> whether the fourth amount of time exceeds a fourth predetermined time threshold. Determining <NUM> whether the fourth amount of time exceeds a fourth predetermined time threshold may be carried out by comparing the fourth amount of time to the fourth predetermined time threshold.

The method of <FIG> also includes responsive to determining that the fourth amount of time does not exceed the fourth predetermined time threshold, determining <NUM> that the contactor is in the open state. Determining <NUM> that the contactor is in the open state may be carried out by storing an indication or flag confirming that the contactor is in the correct state (open state); or sending a signal confirming that the contactor is in the correct state.

The method of <FIG> also includes responsive to determining that the fourth amount of time exceeds the fourth predetermined time threshold, determining <NUM> that the contactor is in the closed state. Determining <NUM> that the contactor is in the closed state may be carried out by transmitting a signal indicating that a fault has occurred or that a specific fault mode has occurred; setting or storing a flag or value that confirms the contactor is in the wrong state (closed state) or that a fault has occurred.

Exemplary embodiments of the present invention are described largely in the context of a fully functional computer system for adjustment of failure mode detection in a contactor. Readers of skill in the art will recognize, however, that the present invention also may be embodied in a computer program product disposed upon computer readable storage media for use with any suitable data processing system. Such computer readable storage media may be any storage medium for machine-readable information, including magnetic media, optical media, or other suitable media. Examples of such media include magnetic disks in hard drives or diskettes, compact disks for optical drives, magnetic tape, and others as will occur to those of skill in the art. Persons skilled in the art will immediately recognize that any computer system having suitable programming means will be capable of executing the steps of the method of the invention as embodied in a computer program product. Persons skilled in the art will recognize also that, although some of the exemplary embodiments described in this specification are oriented to software installed and executing on computer hardware, nevertheless, alternative embodiments implemented as firmware or as hardware are well within the scope of the present invention.

The present invention may be a system, an apparatus, a method, and/or a computer program product.

The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatuses, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatuses or other devices to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks.

Claim 1:
A method for failure mode detection in a contactor (<NUM>), the contactor (<NUM>) including a plunger (<NUM>) and a coil (<NUM>), the coil (<NUM>) configured to be energized with a current or a voltage, the contactor (<NUM>) configured to move the plunger (<NUM>) in response to a change in state of a contactor command signal, the contactor command signal having a first state and a second state, the first state of the contactor command signal directing the plunger (<NUM>) to move to an open position that places the contactor (<NUM>) in an open state in which the contactor (<NUM>) does not connect a first connector and a second connector, the second state of the contactor command signal directing the plunger (<NUM>) to move to a closed position that places the contactor (<NUM>) in a closed state in which the contactor (<NUM>) does connect the first connector and the second connector, the method comprising:
maintaining the contactor command signal in the open state;
connecting the contactor (<NUM>) to a voltage supply that supplies a first predetermined voltage amount to the contactor (<NUM>);
measuring a first amount of time for a magnitude of a coil current of the coil (<NUM>) to exceed a first predetermined current threshold;
determining whether the first amount of time exceeds a first predetermined time threshold;
responsive to determining that the first amount of time does not exceed the first predetermined time threshold, determining that the contactor (<NUM>) is in the open state; and
responsive to determining that the first amount of time exceeds the first predetermined time threshold, determining that the contactor (<NUM>) is in the closed state.