Method and apparatus for handling contactor / relay contact bounce under transient conditions

Abstract

Contact bouncing in the contactor is detected by measuring contact voltage fluctuations caused by bouncing of the powered contacts controlled by the contactor. When a fluctuation is detected, the circuit temporarily re-energizes the contactor's retraction coil to reset the higher magnetic field needed to attract and hold the powered contacts in the proper position to remove the bounce. Because of the high power needed for the retraction coil, the time it is activated is limited to avoid thermal damage to the coil or other electronic components. Activating the retraction coil properly positions the powered contacts, and energizing the lower magnetic field holding coil maintains the position of the powered contacts. The time the retraction coil is activated may be dynamic and may correspond to each disturbance as it occurs, it may be a set time determined by a timer, or it may be controlled by a pulse width modulation scheme.

Description

Detailed Description of the Invention

[0001] [Cross Reference to Related Applications] This application claims the benefit under 35 U.S.C. § 119(e) of Provisional Application No. 63 / 219,684, filed on July 8, 2021, the entire content of which is incorporated herein by reference as if fully set forth herein. [Field of the Invention] The present invention relates generally to contactors, and more specifically to addressing the effects of disturbances that cause contact bouncing in contactors. [Background of the Disclosure] A contactor is essentially a switch actuated by energizing an electromagnet, which in turn pulls a conductive bar across two contacts to bridge them, allowing power to flow across them to a load. In some applications, contactors are used to selectively supply power to specific loads. Firing of firearms on military aircraft causes high transient vibration, which is one example where contacts of an on-board contactor can experience bounce or chattering during a vibration event. This causes arcing that damages the contacts and creates power transients for the load that the contactor is powering. Although contact bounce can be partially mitigated by special vibration-damping mounts for the contactor, such mitigation is often insufficient and / or unreliable.

[0002] As illustrated in Figure 1, an exemplary contactor 100 for high currents comprises two magnetic coils, often arranged in series, to magnetically close the contacts and keep them closed while supplying power to the load. A first coil, referred to as the pull-in coil 102, generates a high magnetic field to quickly close the contacts. A second coil, referred to as the holding coil 104, generates a lower magnetic field to keep or maintain the contacts that have already been closed by the pull-in coil 102 in the closed state. The holding coil 104 is short-circuited by closing the switch 108. Typically, when it is desired to supply power to a particular load, a signal is applied and the switch 108 is closed for a certain period of time. As a result, the pull-in coil 102 sets a higher magnetic field required to operate and close the contacts used to supply power to the load. The high initial magnetic field around the pull-in coil 102 requires a lot of power to generate and is not needed to keep the contacts in the correct position after the contactor is closed; only the holding coil 104 needs to be energized. Therefore, the arrangement of two coils is necessary to minimize the power consumed by the electromagnet.

[0003] Once the power supply contacts are closed, power is supplied to the load, and the switch 108 opens, allowing the retaining coil 104 to set a lower magnetic field (rather than the pull-in coil 102) sufficient to excite it in order to keep the power supply contacts closed. In contrast to the pull-in coil 102, the retaining coil 104 requires a much smaller magnetic field to keep the closed contacts closed or to maintain them. Under highly oscillating conditions or other disturbances, the power supply contacts may bounce or chatter or perform other actions, potentially resulting in arcing, power transients, or other undesirable conditions. During this time, since the contactor is operating using only the lower magnetic field of the retaining coil 104, it may not be able to adequately operate the power supply contacts in a way that would require the higher magnetic field of the pull-in coil 102. This can result in a power supply interruption. It is also undesirable to always use the pull-in coil 102 completely. The reason is that not only is an excessive amount of electricity consumed, but it also generates high levels of thermal energy that could subsequently cause further undesirable malfunctions or conditions. [Overview of the prefecture] The present invention addresses these and other known problems in conventional power supply contactor devices. In embodiments, the present invention detects contact bouncing by measuring fluctuations in the contact voltage caused by the bouncing contact. When these fluctuations are detected, the circuit temporarily re-excites the pull coil to rebuild a higher magnetic field required to pull the contact more firmly, thereby eliminating the bouncing. Due to the high power required for the pull coil, the time the pull coil is operated is limited to avoid thermal damage to the coil or other electronic components. [Brief explanation of the drawing]

[0004] For a more complete understanding of the present invention, its purpose and advantages, please refer here to the accompanying drawings and the related description below. [Figure 1] This is a schematic diagram of a prior art contactor. [Figure 2] This is a schematic diagram of an improved contactor control according to the first embodiment of the present invention. [Figure 3] This is a schematic diagram of an improved contactor control according to a second embodiment of the present invention. [Figure 4] This is a schematic diagram of an improved contactor control according to a third embodiment of the present invention. [Modes for carrying out the invention]

[0005] [Detailed description of embodiments of the invention] Disclosed are several embodiments of the present invention that may be used to selectively control the operation of draw coils within a contactor device in order to minimize the heat generated when supplying power to a load under conditions where disturbances may affect the power supply and / or the operation of the contactor.

[0006] Referring now to Figure 2, which illustrates a schematic diagram of a first embodiment according to the present invention, the contactor 200 comprises a pull-in coil 202 and a retaining coil 204, as described above in relation to Figure 1. However, in this embodiment, a voltage sense 210, such as a differential amplifier, may be used to selectively operate the switch 208, which selectively shorts or opens the retaining coil 204. The inputs to the voltage sense 210 are a high-voltage input 212 and a high-voltage output 214. The high-voltage input 212 represents a vehicle or aircraft power bus, such as a "hot wire," as is well known in electrical systems, while the high-voltage output 214 represents the voltage at the load, or sometimes referred to as the load connection. Under normal operating conditions when power is supplied to the load, the high-voltage input 212 should be essentially identical to the high-voltage output 214, and there should be no (or negligible) output from the voltage sense 210. As a result, the switch 208 remains unchanged, the retaining coil 204 is energized, and the contacts controlled by the retaining coil 204 are closed to supply power to the load.

[0007] If a disturbance occurs while power is being supplied to the load, this typically results in a voltage difference between the high-voltage input 212 and the high-voltage output 214. This voltage difference is detected by the voltage sense 210, which activates the output of the voltage sense 210, thereby short-circuiting the holding coil 204 by acting on the switch 208 to the closed position, and returning the power supply contacts to their predetermined position so that the pull-in coil 202 can increase the magnetic field and reliably supply power to the selected load. As soon as power is properly supplied to the selected load, the high-voltage output 214 should then return to essentially identical with the high-voltage input 212. As soon as this voltage balance is achieved, the differential input to the voltage sense 210 becomes negligible. As a result, the output of the voltage sense 210 is deactivated, and the switch 208 is not actuated. As soon as the switch 208 is no longer actuated, the holding coil 204 is no longer short-circuited and will act to set the magnetic field at a much lower level than required by the pull-in coil 202.

[0008] Unless further disturbances or vibrations are encountered, the power supply contactor will continue to supply power to the load under normal operation, while only the holding coil 204 is excited through a magnetic field much lower than the much higher magnetic field required for the pull-in coil 202. As soon as another disturbance or vibration is detected, which usually manifests as a voltage difference between the high-voltage input 212 and the high-voltage output 214, the voltage sense 210 will activate its output, and the process will continue as described above by closing the switch 208 and re-exciting the pull-in coil 202. In this way, all disturbances or vibrations are detected, for example, by a voltage difference, causing the contactor to reset and the pull-in coil 202 to re-excite.

[0009] Figure 3 presents an alternative embodiment, which operates in much the same manner as the embodiment in Figure 2. Similar elements in Figure 3 are referred to using similar numbering as those used in Figure 2. Referring specifically to Figure 3, the output of the voltage sense 310 is instead used to activate a one-shot timer 316, and instead of directly activating the switch 308 as performed similarly in the embodiment of Figure 2, the one-shot timer 316 activates the switch 308. In the embodiment of Figure 3, for example, once a disturbance or vibration is detected by the voltage sense 310, the output of the voltage sense 310 is used to activate the one-shot timer, which may be programmed to produce an active output for a predetermined time. This active output of the one-shot timer 316 is used to close the switch 308, which then shorts the retaining coil 304, causing the pull coil 302 to set a much higher magnetic field, thereby returning the power supply contacts to or maintaining them in their proper positions. Thus, in contrast to the embodiment of Figure 2, a disturbance or vibration condition may be used to re-excite the pull-in coil 302 for a specific time, which essentially acts in real time or near real time to address each disturbance or vibration event as it occurs. The embodiment of Figure 3 may be advantageous in environments where continuous disturbances may occur or where a large number of disturbances may occur in a relatively short period of time. Instead of having to repeatedly operate the power supply contact, the power supply contact is operated once based on a time set in the one-shot timer 316. If high vibration persists after this time limit is reached and the contact resumes bouncing, the pull-in coil 302 may be re-excited at a different time interval.

[0010] Referring now to Figure 4, Figure 4 illustrates yet another alternative embodiment similar to the embodiment described above, however, in this alternative embodiment, the pull-in coil 402 is supplied with a reduced average current, which results in a much higher magnetic field than that generated by the holding coil 404 alone, but is smaller than the current resulting from fully operating the pull-in coil 402. Figure 4 presents the alternative embodiment, which operates almost identically to the embodiment in Figure 2. Similar elements in Figure 4 are referred to using similar numbers to those used in Figure 2. Referring specifically to Figure 4, the output of the voltage sense 410 is instead used to operate the logic circuit 416, which then produces pulse-width modulation (PWM) outputs such as signal sequences 418 and 420. Then, a PWM signal such as 418 or 420 is used to activate switch 408 and short-circuit the retaining coil 404 when it is necessary to set a high magnetic field by the pull-in coil 402 to return the voltage supply contacts to their proper positions or to keep them in their proper positions. The PWM approach in Figure 4 still utilizes far less current and generates far less thermal energy than if the pull-in coil 402 were constantly excited. This is because the pull-in coil 402 is excited only for a limited period of time. This ON time period is otherwise called the duty cycle and may be set based on specific requirements or desired operation of the system.

[0011] As described above in relation to various embodiments, the amount of current required to keep the power supply contacts closed may be predetermined based on the aircraft or vehicle design. Furthermore, a software algorithm or digital logic may be designed to begin reducing the current to the pull-in coil after a certain period of time, reducing the current to zero when the vibration stops, or increasing the current again when contact chattering resumes.

[0012] It will be understood that the embodiments disclosed herein extend to all substitutions and combinations. It will be further understood by those skilled in the art that the present invention is applicable to a wide range of uses and applications. Many embodiments and variations of the present invention other than those described herein, as well as many adaptations, modifications, and equivalent devices, will be apparent from or reasonably suggested by the present invention and its description without departing from the spirit or scope of the invention.

[0013] Therefore, while the present invention is described in detail herein in relation to exemplary embodiments, this disclosure should be understood to be merely illustrative and illustrative of the invention and made to provide a fully implementable disclosure. Furthermore, the foregoing description is not intended to be construed as limiting to the invention or excluding any adaptations, modifications, or equivalents thereof.

Claims

1. A circuit device capable of reducing contact bounce in a contactor caused by transient conditions, A contactor having a first magnetic coil electrically connected to a second magnetic coil, wherein one or both of the first and second magnetic coils are configured to close the contacts when power is supplied to a load, and the first magnetic coil generates a higher magnetic field than the second magnetic coil, The first magnetic coil is configured to selectively short-circuit the second magnetic coil electrically so that it can generate a higher magnetic field, and A voltage sensor configured to detect voltage fluctuations caused by the transient state, wherein the voltage sensor has an output used to generate a higher magnetic field by selectively activating the switch to excite the first magnetic coil. A circuit device equipped with the following features.

2. The circuit device according to claim 1, The first magnetic coil includes a pull-in coil, The aforementioned second magnetic coil includes a holding coil, A circuit device in which the pull-in coil and the holding coil are connected in series.

3. The circuit device according to claim 2, The circuit device includes a differential amplifier having a first input that is conductive to a power bus and a second input that is conductive to a load voltage connection, wherein the output of the differential amplifier is configured to indicate the voltage difference between the power bus and the load voltage connection.

4. The circuit device according to claim 3, A circuit device in which the pull-in coil is temporarily energized when a disturbance is detected and de-energized when the disturbance is no longer detected.

5. A circuit device capable of reducing contact bounce in a contactor caused by transient conditions, A contactor having a first magnetic coil electrically connected to a second magnetic coil, wherein one or both of the first and second magnetic coils are configured to close contacts when power is supplied to a load, and the first magnetic coil generates a higher magnetic field than the second magnetic coil, A switch configured to selectively short-circuit the second magnetic coil so that the first magnetic coil can generate a higher magnetic field, A voltage sensor configured to detect voltage fluctuations caused by the transient state, having an output used to selectively activate a timer, wherein the timer excites the first magnetic coil by operating the switch for a selectable time, thereby generating the higher magnetic field. A circuit device equipped with the following features.

6. The circuit device according to claim 5, The first magnetic coil includes a pull-in coil, The aforementioned second magnetic coil includes a holding coil, A circuit device in which the pull-in coil and the holding coil are connected in series.

7. The circuit device according to claim 6, The circuit device comprises a differential amplifier having a first input that is conductive to a power bus and a second input that is conductive to a load voltage connection, wherein the output of the differential amplifier is configured to indicate the voltage difference between the power bus and the load voltage connection.

8. The circuit device according to claim 7, The pull-in coil is temporarily energized when a disturbance is detected and de-energized after the selectable time has elapsed, in a circuit device.

9. A circuit device capable of reducing contact bounce in a contactor caused by transient conditions, A contactor having a first magnetic coil electrically connected to a second magnetic coil, wherein one or both of the first and second magnetic coils are configured to close contacts when power is supplied to a load, and the first magnetic coil generates a higher magnetic field than the second magnetic coil, A switch configured to selectively short-circuit the second magnetic coil so that the first magnetic coil can generate a higher magnetic field, A voltage sensor configured to detect voltage fluctuations caused by the transient state, wherein the voltage sensor has an output used to operate a pulse width modulator having a selectable duty cycle, the output of the pulse width modulator excites a first magnetic coil by selectively operating the switch on and off according to the selectable duty cycle, thereby generating the higher magnetic field, A circuit device equipped with the following features.

10. The circuit device according to claim 9, The first magnetic coil includes a pull-in coil, The aforementioned second magnetic coil includes a holding coil, A circuit device in which the pull-in coil and the holding coil are connected in series.

11. The circuit device according to claim 10, The circuit device comprises a differential amplifier having a first input that is conductive to a power bus and a second input that is conductive to a load voltage connection, wherein the output of the differential amplifier is configured to indicate the voltage difference between the power bus and the load voltage connection.

12. The circuit device according to claim 11, A circuit device in which the pull-in coil is temporarily energized when a disturbance is detected and de-energized according to the selectable duty cycle of the pulse width modulator.

13. A method for reducing contact bounce in a contactor caused by transient conditions, A step of using a contactor having a first magnetic coil electrically connected to a second magnetic coil, wherein one or both of the first and second magnetic coils are configured to close the contacts when power is supplied to a load, and the first magnetic coil generates a higher magnetic field than the second magnetic coil. A step of selectively operating a switch configured to selectively short-circuit the second magnetic coil so that the first magnetic coil can generate a higher magnetic field than described above, A step of utilizing a voltage sensor configured to detect voltage fluctuations caused by the transient state, wherein the voltage sensor has an output used to excite the first magnetic coil by selectively activating the switch, thereby generating the higher magnetic field. A method that includes [something].

14. The method according to claim 13, The first magnetic coil includes a pull-in coil, The aforementioned second magnetic coil includes a holding coil, A method in which the pull-in coil and the holding coil are connected in series.

15. The method according to claim 14, A method comprising a differential amplifier, wherein the voltage sensor is a differential amplifier having a first input that is conductive to a power bus and a second input that is conductive to a load voltage connection, and the output of the differential amplifier is configured to indicate the voltage difference between the power bus and the load voltage connection.

16. The method according to claim 15, A method wherein the pull-in coil is temporarily energized when a disturbance is detected and de-energized when the disturbance is no longer detected.

17. A method for reducing contact bounce in a contactor caused by transient conditions, A step of using a contactor having a first magnetic coil electrically connected to a second magnetic coil, wherein one or both of the first and second magnetic coils are configured to close the contacts when power is supplied to a load, and the first magnetic coil generates a higher magnetic field than the second magnetic coil. A step of selectively operating a switch configured to selectively short-circuit the second magnetic coil so that the first magnetic coil can generate a higher magnetic field than described above, A step of utilizing a voltage sensor configured to detect voltage fluctuations caused by the transient state, wherein the voltage sensor has an output used to selectively activate a timer, and the timer excites the first magnetic coil by operating the switch for a selectable time to generate the higher magnetic field. A method that includes [something].

18. The method according to claim 17, The first magnetic coil includes a pull-in coil, The aforementioned second magnetic coil includes a holding coil, A method in which the pull-in coil and the holding coil are connected in series.

19. The method according to claim 18, A method comprising a differential amplifier, wherein the voltage sensor is a differential amplifier having a first input that is conductive to a power bus and a second input that is conductive to a load voltage connection, and the output of the differential amplifier is configured to indicate the voltage difference between the power bus and the load voltage connection.

20. The method according to claim 19, A method wherein the pull-in coil is temporarily energized when a disturbance is detected and de-energized after the selectable time has elapsed.

21. A method for reducing contact bounce in a contactor caused by transient conditions, A step of using a contactor having a first magnetic coil electrically connected to a second magnetic coil, wherein one or both of the first and second magnetic coils are configured to close the contacts when power is supplied to a load, and the first magnetic coil generates a higher magnetic field than the second magnetic coil. A step of selectively operating a switch configured to selectively short-circuit the second magnetic coil so that the first magnetic coil can generate a higher magnetic field than described above, A step of utilizing a voltage sensor configured to detect voltage fluctuations caused by the transient state, wherein the voltage sensor has an output used to operate a pulse width modulator having a selectable duty cycle, and the output of the pulse width modulator excites the first magnetic coil by selectively operating the switch on and off according to the selectable duty cycle, thereby generating the higher magnetic field. A method that includes [something].

22. The method according to claim 21, The first magnetic coil includes a pull-in coil, The aforementioned second magnetic coil includes a holding coil, A method in which the pull-in coil and the holding coil are connected in series.

23. A method according to claim 22, A method comprising a differential amplifier, wherein the voltage sensor is a differential amplifier having a first input that is conductive to a power bus and a second input that is conductive to a load voltage connection, and the output of the differential amplifier is configured to indicate the voltage difference between the power bus and the load voltage connection.

24. The method according to claim 23, A method wherein the pull-in coil is temporarily energized when a disturbance is detected and de-energized according to the selectable duty cycle of the pulse width modulator.

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