Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
  • H01H47/02—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current for modifying the operation of the relay
  • H01H47/12—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current for modifying the operation of the relay for biasing the electromagnet
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H47/00—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current
  • H01H47/02—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current for modifying the operation of the relay
  • H01H47/04—Circuit arrangements not adapted to a particular application of the relay and designed to obtain desired operating characteristics or to provide energising current for modifying the operation of the relay for holding armature in attracted position, e.g. when initial energising circuit is interrupted; for maintaining armature in attracted position, e.g. with reduced energising current
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H2201/00—Contacts
  • H01H2201/002—Contacts bounceless

Definitions

• the present invention generally relates to contactors, and more specifically relates to addressing disturbance effects causing bouncing contacts in contactors.
• a contactor is essentially a switch that is actuated by powering an electromagnet, which in turn pulls a conductive bar across two contacts, bridging them and allowing power to flow across them into a load.
• a contactor is used to selectively deliver power to a particular load. Firing a military aircraft’s guns causes a high transient vibration and is one instance where an onboard contactor’s contacts can bounce or chatter during the vibration event. This causes damaging contact arcing and creates power transients to the loads that the contactor is powering. Contact bounce can be partially mitigated by special vibration dampening mounts for the contactors, however, such mitigation is often insufficient and/or unreliable.
• an exemplary contactor 100 for high currents has two magnetic coils, usually arranged is series, to magnetically close the contacts and to keep them closed while providing power to the loads.
• the first coil called the pull-in coil 102
• the second coil called the hold coil 104
• the hold coil 104 creates a lower magnetic field to keep or maintain the contacts in a closed state once they have already been closed by the pull-in coil 102.
• the hold coil 104 is shorted by closing switch 108.
• a signal is applied to cause switch 108 to close for some period of time.
• the two-coil arrangement is required to minimize the power dissipated by the electromagnet, as the high initial magnetic field for the pull-in coil 102 requires a great deal of power to create and is not needed to hold the contacts in place after the contactor has closed and only the hold coil 104 needs to be energized.
• the switch 108 is opened, thereby allowing the hold coil 104 to set a lower magnetic field sufficient to energize the hold coil 104 (but not the pull-in coil 102) in order to keep the power delivery contacts closed.
• the hold coil 104 needs a much smaller magnetic field in order to keep or maintain the closed contacts in a closed state. Under high vibration conditions or other disturbances, the power delivery contacts may bounce or chatter, or otherwise move, resulting in arcing, power transients, or other undesirable conditions.
• the contactor Since during this time, the contactor is operating using only a lower magnetic field hold coil 104, the contactor may not be able to sufficiently move the power delivery contacts, which otherwise requires the higher magnetic field pull-in coil 102. This results in interrupted power delivery. Fully engaging the pull-in coil 102 all the time is also undesirable, as it results in an excessive amount of power being consumed, as well as generating high levels of thermal energy which in turn may cause additional undesirable faults or conditions.
• the present invention addresses these and other noted deficiencies in conventional power delivery contactor arrangements.
• the present invention detects contact bouncing by measuring contact voltage fluctuations caused by the bouncing contacts. When these fluctuations are detected, a circuit causes the pull-in coil to be temporarily re energized to re-establish the higher magnetic field needed to pull the contacts tighter together, which eliminates the bouncing. Because of the high power required by the pull-in coil, the time that it is actuated is limited in order to avoid thermal damage to the coil or other electronic components.
• Figure l is a schematic diagram of a prior art contactor
• Figure 2 is a schematic diagram of an improved contactor control according to a first embodiment of the present invention.
• Figure 3 is a schematic diagram of an improved contactor control according to a second embodiment of the present invention.
• Figure 4 is a schematic diagram of an improved contactor control according to a third embodiment of the present invention.
• the contactor 200 includes a pull-in coil 202 and a hold coil 204, as described above in connection with Figure 1.
• a voltage sense 210 such as, for example, a differential amplifier, may be used to selectively activate switch 208, which in turn selectively shorts or opens hold coil 204.
• the inputs to voltage sense 210 are high voltage in 212 and high voltage out 214.
• High voltage in 212 represents the vehicle or aircraft’s power bus, akin to the “hot wire” as is commonly known in electrical systems, while the high voltage out 214 represents the voltage at the load, or what is sometimes referred to as the load connection.
• high voltage in 212 should essentially be the same as high voltage out 214, resulting in no (or negligible) output from voltage sense 210.
• switch 208 is otherwise unchanged, the hold coil 204 is energized and the contacts controlled by the hold coil 204 are closed in order to deliver power to the load. [0013] If a disturbance occurs while power is being delivered to a load, this will typically cause a difference between the voltages seen at high voltage in 212 and high voltage out 214.
• This voltage difference is detected by voltage sense 210, causing its output to activate, which in turn activates switch 208 to a closed position, thereby shorting hold coil 204, and allowing pull-in coil 202 to increase the magnetic field, thereby moving the power delivery contacts back into place in order to reliably deliver power to the selected load.
• the high voltage out 214 should revert back to essentially being the same as high voltage in 212.
• the differential input to voltage sense 210 will become negligible.
• the output of voltage sense 210 will be deactivated, which in turn will cause deactivation of switch 208.
• the hold coil 204 is no longer shorted and will act to set the magnetic field at a much lower level than what was needed by pull-in coil 202.
• the power delivery contactor will continue under normal operation, with power being delivered to the load, while only hold coil 204 is energized by way of a lower magnetic field, as compared with the much higher magnetic field required by pull-in coil 202.
• this will typically manifest as a voltage difference between high voltage in 212 and high voltage out 214, and voltage sense 210 will have its output activated, and the process will continue as described above, by closing switch 208 and causing the pull-in coil 202 to energize once again. In this way, every disturbance or vibration is sensed, for example, by way of a voltage difference, and the contactor reset to energize the pull-in coil 202.
• Figure 3 presents an alternative embodiment, which operates much in the same way as that of Figure 2.
• the similar elements in Figure 3 are labelled using similar numbering as that used in Figure 2.
• the output of voltage sense 310 is instead used to activate a one shot timer 316, which in turn activates switch 308, instead of activating switch 308 directly, as is similarly performed in the embodiment of Figure 2.
• the output of voltage sense 310 is used to activate a one shot timer, which may be programmed to provide an active output for a preselected amount of time.
• This active output of the one shot timer 316 is what is used to close switch 308, which in turn shorts the hold coil 304, causing the pull-in coil 302 to set a much higher magnetic field to thereby cause the power delivery contacts to move back into or be maintained in their proper position.
• a disturbance or vibration condition may be used to re-energize pull-in coil 302 for a specific period of time, as opposed to the embodiment of Figure 2, which essentially acts in real-time or near real-time to deal with each disturbance or vibration event as it occurs.
• the embodiment of Figure 3 may be advantageous in environments where it is known that successive disturbances may occur, or alternatively, that multiple disturbances may occur within a relatively short period of time.
• the power delivery contacts are moved once based on the time set for the one shot timer 316. If the high vibration continues to exist after this time limit is reached and the contacts resume bouncing, the pull-in coil 302 may be re-energized for another time interval.
• FIG 4 therein is illustrated yet another alternative embodiment similar to the above-described embodiments, but where the pull-in coil 402 is provided with a reduced average current that provides a much higher magnetic field than that created by the hold coil 404 alone, but is less than that provided from fully actuating the pull-in coil 402.
• Figure 4 presents an alternative embodiment, which operates much in the same way as that of Figure 2.
• the similar elements in Figure 4 are labelled using similar numbering as that used in Figure 2.
• the output of voltage sense 410 is instead used to activate a logic circuit 416, which in turn provides a pulse-width modulated (PWM) output, such as signal sequence 418 and 420.
• PWM pulse-width modulated
• the PWM signal such as 418 or 420, is in turn used to activate switch 408, and thereby short hold coil 404 when it is needed to have pull-in coil 402 set a higher magnetic field to cause the power delivery contacts to move back in or be maintained in their proper position.
• the PWM approach of Figure 4 still utilizes much less current and generates much less thermal energy than having pull-in coil 402 be constantly energized. This is because the pull-in coil 402 is being energized for only part of a time period.
• the ON time of the period otherwise referred to as the duty cycle, may be set based on the particular requirements or desired operation of a system.
• the amount of current required to hold the power delivery contacts closed may be pre-determined based on the aircraft or vehicle design
• a software algorithm or digital logic can be made to start reducing the current to the pull-in coil after a set amount of time, reducing it to zero if the vibration has ceased, or alternatively, increasing the current again if contact chatter resumes.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Relay Circuits (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 2022
  • 2022-07-08 EP EP22838489.7A patent/EP4360114A1/de active Pending
  • 2022-07-08 WO PCT/US2022/036571 patent/WO2023283455A1/en active Application Filing
  • 2022-07-08 CA CA3223861A patent/CA3223861A1/en active Pending

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