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Apparatus and methods thereof for error correction in split core current transformers

  • US 9,678,114 B2
  • Filed: 03/14/2014
  • Issued: 06/13/2017
  • Est. Priority Date: 04/16/2009
  • Status: Active Grant
First Claim
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1. An apparatus comprising:

  • at least one analog section comprising a current transformer having a transformer core configured to mount around an alternating current (AC) power line alternating at a fixed frequency making the AC power line a primary winding of the current transformer and further comprising a resonance capacitor connected in parallel to a secondary winding of the current transformer to resonate with the secondary winding inductance at the primary fixed frequency, the resonance capacitor'"'"'s value being selected so that maximum resonance is achieved at low currents of the primary winding and at a low non-linear range of a magnetization curve of the transformer core, the analog section for harvesting energy from the secondary winding on the transformer core, and storing it for use by components of the apparatus and periodically switching to allow sampling of a current flowing through the current transformer by a sense resistor;

    a memory containing therein at least a calibration coefficient for correction of a vector generated respective of the sampling of a current flowing through the current transformer, the vector including a plurality of cycles over a plurality of periods of the fixed frequency;

    a microcontroller connected to the at least one analog section to receive harvested energy and to the memory, to determine;

    the vector, at least a value respective of the vector the value corrected as the at least a calibration coefficient, a time stamp;

    a transmitter connected to the microcontroller enabled to periodically transmit, under the control of the microcontroller the at least a value, the time stamp, and the at least a calibration coefficient;

    such that a receiver of the at least a value may use the at least a value for determination of at least an electrical parameter.

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