×

Sensor and method for foreign object detection in induction electric charger

  • US 9,829,599 B2
  • Filed: 03/23/2015
  • Issued: 11/28/2017
  • Est. Priority Date: 03/23/2015
  • Status: Active Grant
First Claim
Patent Images

1. A device for detecting foreign objects near a primary coil of an induction charger, comprising:

  • a sensor array located adjacent to the primary coil of the induction charger, the array covering at least a portion of the primary coil area, and containing sensors, each sensor configured to output a sensing signal in response to magnetically coupling a high frequency alternating magnetic field produced by the primary coil, the magnetic field produced by the primary coil having a spatial distribution of magnetic intensity that varies by location across the primary coil area, each sensor of the array being configured to have a magnetic field sensing sensitivity that is inversely proportional to the magnetic intensity of the magnetic field produced by the primary coil at a location of the sensor with respect to the primary coil area; and

    a controller coupled to the sensors, the controller configured to scan the sensing signal of each sensor in the array, compute a two-dimensional convolution transform on the received sensing signals, the two-dimensional convolution transform being configured to detect sharp changes of two dimensional images of magnetic intensity produced by a combination of the primary coil and the foreign object, the sharp changes indicating the presence of the foreign object proximate to the sensors and compute a modified two-dimensional convolution transform on the sensing signals received from the sensors in the array, where the sensors in the array are juxtaposed with a magnetic intensity produced by the primary coil, which undergoes an inversion that changes a direction of the magnetic intensity produced by the primary coil thereby determining from the scanned sensing signals, which sensors in the array are outputting a sensing signal indicating presence of the foreign object proximate to the sensors, the foreign object causing a perturbation in the high frequency alternating magnetic field near the sensors.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×