Active RFID asset tracking tag with current-sensing cable clamp
First Claim
Patent Images
1. An active radio frequency identifier (RFID) tag comprising:
- a clamp assembly configured to clamp around an AC power cable that comprises an outer insulator wrapped around two or more insulated inner conductors, wherein the clamp assembly includes a plurality of magnetic field sensors spaced around the outer insulator of the AC power cable, wherein the magnetic field sensors are configured to generate magnetic field strength measurements at different positions around the AC power cable, wherein the magnetic field strength measurements are used collectively to generate an estimate of electrical current flowing through one inner conductor of the AC power cable to a host device to which the RFID tag is associated;
a processor coupled to the plurality of magnetic field sensors and configured to search for a combination of AC power cable parameters, including instantaneous current, that best match a mathematical model of expected magnetic field strength at each magnetic field sensor position to the magnetic field strength measurements, and use an estimate of instantaneous current as a final current estimate of current flowing through the one conductor in the AC power cable; and
an enclosure configured to contain a battery and a wireless transceiver.
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Abstract
Configurations are provided for measuring electrical current flow through an AC power cable to a host device. An enclosure is provided that includes various components, such as components of an active RFID tag. A cable clamp is provided that is configured to attach the enclosure to the AC power cable. The cable clamp includes magnetic sensors that are responsive to electrical current flowing through the AC cable to generate signals indicative of the current flowing through the AC cable.
42 Citations
24 Claims
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1. An active radio frequency identifier (RFID) tag comprising:
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a clamp assembly configured to clamp around an AC power cable that comprises an outer insulator wrapped around two or more insulated inner conductors, wherein the clamp assembly includes a plurality of magnetic field sensors spaced around the outer insulator of the AC power cable, wherein the magnetic field sensors are configured to generate magnetic field strength measurements at different positions around the AC power cable, wherein the magnetic field strength measurements are used collectively to generate an estimate of electrical current flowing through one inner conductor of the AC power cable to a host device to which the RFID tag is associated; a processor coupled to the plurality of magnetic field sensors and configured to search for a combination of AC power cable parameters, including instantaneous current, that best match a mathematical model of expected magnetic field strength at each magnetic field sensor position to the magnetic field strength measurements, and use an estimate of instantaneous current as a final current estimate of current flowing through the one conductor in the AC power cable; and an enclosure configured to contain a battery and a wireless transceiver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A device comprising:
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a clamp assembly configured to clamp around an AC power cable that comprises an outer insulator wrapped around two or more insulated inner conductors, wherein the clamp assembly includes a plurality of magnetic field sensors spaced around the outer insulator of the AC power cable, wherein the magnetic field sensors are configured to generate magnetic field strength measurements at different positions around the AC power cable; and an enclosure configured to contain a battery and a processor; wherein the processor is configured to generate an estimate of current flow through one inner conductor of the AC power cable from outputs of the plurality of magnetic field sensors by searching for a combination of AC power cable parameters, including instantaneous current, that best match a mathematical model of magnetic field readings at the different positions around the AC power cable from the plurality of magnetic field sensors, and using an estimate of instantaneous current as a final current estimate of current flowing through the one conductor in the AC power cable. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. An active radio frequency identifier (RFID) tag comprising:
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a clamp assembly configured to clamp around an AC power cable that comprises an outer insulator wrapped around two or more insulated inner conductors, wherein the clamp assembly includes a plurality of magnetic field sensors spaced around the outer insulator of the AC power cable and configured to generate magnetic field strength measurements at different positions around the AC power cable, wherein the magnetic field strength measurements are used collectively to generate an estimate of electrical current flowing through one inner conductor of the AC power cable; a processor coupled to the plurality of magnetic field sensors and configured to search a combination of AC power cable parameters, including instantaneous current, that best match a mathematical model of expected magnetic field strength at each magnetic field sensor position to the magnetic field strength measurements, and use an estimate of instantaneous current as a final current estimate of current flowing through the one conductor in the AC power cable; and an enclosure configured to contain a rechargeable battery, a wireless transceiver, and a combiner circuit configured to combine output signals from the magnetic field sensors to produce power to charge the rechargeable battery. - View Dependent Claims (21, 22, 23, 24)
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Specification