Method and device for foreign object detection in induction electric charger

• US 9,893,557 B2
• Filed: 07/12/2013
• Issued: 02/13/2018
• Est. Priority Date: 07/12/2013
• Status: Active Grant

• Current Assignee: Schneider Electric USA, Inc. (Schneider Electric SE)
• Original Assignee: Schneider Electric USA, Inc. (Schneider Electric SE)
• Inventors: Filippenko, Alexander, Kocher, Mark
• Primary Examiner(s): Tso, Edward
• Application Number:
  US14/904,209
• Publication Number:
  US 20160172891A1
• Time in Patent Office: 1,677 Days
• Field of Search: 320107, 320108, 320114, 32420713, 32420714, 32420715, 32420717
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge

Abstract

An example embodiment of the invention is a method and device for detecting foreign objects (FO) near the primary coil of an induction charger used in charging electric vehicle batteries. Individual sensors of a sensor array are configured to output a sensing signal in response to magnetically coupling the high frequency alternating magnetic field produced by the primary coil. A disable signal line is configured to disable the power source when a controller determines from scanned sensor signals, that a FO is present. An alarm can be activated by the microprocessor to alert the user to the presence of a FO on or near the primary coil. In this manner, damage can be avoided that could otherwise be caused from the presence of a FO near the primary coil. Moreover, a more efficient charging operation can be achieved by avoiding dissipating energy by heating a FO.

Claims

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

a sensor array arranged in rows of sensors, each row containing sensors arranged in respective columns, the array located adjacent to the primary coil of the induction charger and covering at least a portion of the primary coil, each sensor configured to output a sensing signal in response to magnetically coupling a high frequency alternating magnetic field produced by the primary coil;

a controller coupled to each respective row of sensors and each respective column of sensors, the controller configured to scan the sensing signal of each sensor in the array and determine from the scanned sensing signals, which sensors in the array are outputting a sensing signal indicating the presence of the foreign object proximate to the sensors, the foreign object causing a perturbance in the high frequency alternating magnetic field near the sensors; and

means for blocking sensors from coupling to the controller when the sensor is not being scanned by the controller, and coupling the sensor to the controller when the sensor is being scanned by the controller.

2. The device for detecting foreign objects near a primary coil of an induction charger of claim 1, further comprising:

a disable signal line coupled from the controller to a control input of a power source of the primary coil, configured to disable the power source when the controller determines from the scanned sensor signals, that there is a scanned sensor signal indicating presence of a foreign object.

3. The device for detecting foreign objects near a primary coil of an induction charger of claim 1, wherein the controller comprises:

a microprocessor for determining when a foreign object has been detected near the primary coil;

a memory, associated with the microprocessor;

a column multiplexer connected to each sensor in the columns of sensors;

a row multiplexer connected to each sensor in the rows of sensors; and

a sensor signal measurement unit for processing the sensing signals received from the sensors and passing the results to the microprocessor.

4. The device for detecting foreign objects near a primary coil of an induction charger of claim 3, wherein the column multiplexer comprises:

a gate coupled to each respective column, wherein when the microprocessor selects a column, it sends an enabling signal to enable the gate for that column, to couple the column to a reference potential.

5. The device for detecting foreign objects near a primary coil of an induction charger of claim 3, wherein the row multiplexer comprises:

a gate coupled to each respective row, wherein when the microprocessor selects a row, it sends an enabling signal to enable the gate for that row, to couple the row to the sensor signal measurement unit.

6. The device for detecting foreign objects near a primary coil of an induction charger of claim 3, wherein a signal derived from the sensor signal induced in the sensor by the alternating magnetic field of the primary coil, is measured by the measurement unit and the measured value sent to the microprocessor to determine whether there is a foreign object present.

7. The device for detecting foreign objects near a primary coil of an induction charger of claim 3, wherein measurements by the sensor signal measurement unit can be stored in the memory as a pattern of the magnetic field produced by the primary coil and used by the microprocessor as a self-calibration baseline for foreign object detection.

8. The device for detecting foreign objects near a primary coil of an induction charger of claim 7, wherein the pattern of the magnetic field produced by the primary coil is significantly altered by the perturbance in that magnetic field caused by a foreign object near the primary coil of the induction charger.

9. The device for detecting foreign objects near a primary coil of an induction charger of claim 8, wherein the significantly altered pattern is compared with the stored baseline pattern to determine the presence of a foreign object near the primary coil.

10. The device for detecting foreign objects near a primary coil of an induction charger of claim 3, wherein the sensor has a first terminal connected to a row line coupled to the row multiplexer, and a second terminal connected to a column line coupled to the column multiplexer.

11. The device for detecting foreign objects near a primary coil of an induction charger of claim 3, wherein the sensor has a first terminal connected to a row line coupled to the row multiplexer, and a second terminal connected to a column line coupled to the column multiplexer, a diode being connected in series between the sensor and one of the row line or the column line.

12. The device for detecting foreign objects near a primary coil of an induction charger of claim 3, wherein the sensor has a first terminal connected to a row line coupled to the row multiplexer, and a second terminal connected to a column line coupled to the column multiplexer, a diode being connected in series between the sensor and one of the row line or the column line, the diode being reverse biased to block coupling to the sensor signal measurement unit when the sensor is not selected by the microprocessor, and the diode being forward biased to couple to the sensor signal measurement unit when the sensor coil is selected by the microprocessor.

13. The device for detecting foreign objects near a primary coil of an induction charger of claim 3, wherein the sensor is a magnetodiode connected in series with a row line and a column line, the magnetodiode being reverse biased to block coupling to the sensor signal measurement unit when the sensor is not selected by the microprocessor and the magnetodiode being forward biased to couple to the sensor signal measurement unit when the sensor is selected by the microprocessor.

14. The device for detecting foreign objects near a primary coil of an induction charger of claim 1, further comprising:

an alarm signal line coupled from the controller to an alarm unit, configured to announce an alarm when the controller determines from the scanned sensor signals, that there is a scanned sensor signal indicating presence of a foreign object.

15. The device for detecting foreign objects near a primary coil of an induction charger of claim 1, wherein the sensors are drawn from the group consisting of printed circuit coils, Hall-effect sensors, MEMS sensors incorporating a strain-gauge reading of magnetic force, Giant Magnetoresistive (GMR) sensors, Magneto-optical sensors, magnetotransistors and magnetodiodes.

16. The device for detecting foreign objects near a primary coil of an induction charger of claim 1, wherein connector lines to the rows of sensors are twisted with connector lines to the columns of sensors, to minimize magnetic field coupling of the connector lines by a high frequency alternating magnetic field produced by the primary coil.

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

sensing, by each of a plurality of sensors in a sensor array covering at least a portion of the primary coil, a high frequency alternating magnetic field produced by the primary coil, the sensor array arranged in rows of sensors, each row containing sensors arranged in respective columns;

scanning, by a controller coupled to each respective row of the sensor array and each respective column of the sensor array, sensor signals output by the plurality of sensors in the sensor array, in response to the sensors magnetically coupling the high frequency alternating magnetic field produced by the primary coil;

blocking sensors from coupling to the controller when the sensor is not being scanned by the controller, and coupling sensors to the controller when the sensor is being scanned by the controller; and

determining, by the controller coupled to the sensor array, whether there is sensor in the sensor array that is outputting a sensor signal indicating presence of a foreign object proximate to the sensor, which is perturbing the high frequency alternating magnetic field near the sensor.

18. The method for detecting foreign objects near a primary coil of an induction charger, of claim 17, further comprising:

sending, by the controller coupled to the sensor array, a disable signal to a control input of a power source of the primary coil, to disable the power source when the controller determines from the scanned sensor signals, that there is a scanned sensor signal indicating presence of a foreign object.

19. The method for detecting foreign objects near a primary coil of an induction charger, of claim 17, further comprising:

sending, by the controller coupled to the sensor array, an alarm signal to an alarm unit, to announce an alarm when the controller determines from the scanned sensor signals, that there is a scanned sensor signal indicating presence of a foreign object.