Method and system for providing induction charging having improved efficiency

• US 6,917,182 B2
• Filed: 07/24/2003
• Issued: 07/12/2005
• Est. Priority Date: 07/24/2003
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Burton, Andrew F., Patino, Joseph, Simpson, Russell L.
• Primary Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US10/626,333
• Publication Number:
  US 20050017677A1
• Time in Patent Office: 719 Days
• Field of Search: 320/108, 320/119, 320/139, 307/10.1, 323/258, 318/364, 318/701
• US Class Current: 320/108
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H04M 19/08 with current supply sources at the substations generating ringing current H04M19/04
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers

Abstract

A battery charging system (250) for use with an induction charger (210). The battery charging system can include a secondary coil (252) having a plurality of turns for receiving magnetic flux produced by a primary coil (220) of the induction charger, and a control circuit (254) for controlling a number of turns of the secondary coil that are used in generating an output voltage for charging a cell (264). For example, the secondary coil can include a plurality of taps (291, 292, 293, 294), each of the taps providing an electrical connection to the coil at a different point, and thus providing a variety of selectable output voltages.

Claims

1. A battery charging system for use with an induction charger, comprising:

a plurality of secondary coils coupled to a corresponding plurality of cells for simultaneously receiving magnetic flux produced by a primary coil of the induction charger when said plurality of secondary coils is placed proximately to a base coupled to the induction charger, each of said plurality of secondary coils having a plurality of turns; and

a corresponding control circuit coupled to each of said plurality of secondary coils for controlling a number of turns of each of said secondary coils for simultaneously charging the plurality of cells.

2. The battery charging system of claim 1, wherein said control circuit controls said number of turns responsive to at least one condition from the group consisting of a desired voltage to be applied to the corresponding cell of said secondary coil, a temperature of said at least one cell, and a charge current.

3. The battery charging system of claim 1, wherein each of said plurality of secondary coils further comprises a plurality of taps, each of said taps providing an electrical connection to said secondary coil.

4. The battery charging system of claim 3, wherein a flow of time-varying electric current through said primary coil generates a voltage potential between at least two of said plurality of taps.

5. The battery charging system of claim 4, further comprising at least one switch responsive to a control signal generated by said control circuit, said switch operable between a first position wherein a first voltage is applied from a first of said plurality of taps to said at least one cell, and a second position wherein a second voltage is applied from a second of said taps to said at least one cell.

6. The battery charging system of claim 5, wherein said switch comprises at least one device selected from the group consisting of a transistor, a relay, and a mechanical switch.

7. The battery charging system of claim 1, wherein each secondary coil and corresponding control circuit and corresponding cell are contained within a battery.

8. The battery charging system of claim 1, wherein each secondary coil and corresponding control circuit and corresponding cell are contained within a battery operated device.

9. The battery charging system of claim 8, wherein said corresponding cell is detachable from said battery operated device.

10. An induction charging system, comprising:

(a) an induction charger, comprising;

a base for charging;

a primary coil coupled to said base; and

a power supply which supplies a time-varying electric current to said primary coil; and

(b) a plurality of battery operated devices each carrying at least one cell, wherein each of the battery operated devices includes a battery charging system for simultaneously charging the at least one cell when the plurality of battery operated devices is placed proximately to said base, said battery charging system comprising;

a secondary coil for receiving magnetic flux produced by said primary coil of said induction charger, said secondary coil having a plurality of turns and generating an output voltage responsive to said received magnetic flux; and

a control circuit for controlling a number of turns of said secondary coil to adjust the output voltage according to a desired voltage to be applied to said at least one cell.

11. The induction charging system of claim 10, wherein the base is substantially flat.

12. The charging system of claim 10, wherein said control circuit further controls said number of turns responsive to at least one condition from the group consisting of a temperature of said at least one cell and a charge current.

13. A method for simultaneously charging a plurality of cells each coupled to a corresponding plurality of secondary coils, comprising the steps of:

placing the plurality of secondary coils and corresponding plurality of cells proximately to a base of an induction charger;

receiving at the plurality of secondary coils a magnetic flux produced by the induction charger, each of said plurality of secondary coils having a plurality of turns that are used in charging the corresponding plurality of cells; and

controlling a number of turns for each of said plurality of secondary coils to generate a desired voltage to be applied to the corresponding cell of said secondary coil.

14. The method of claim 13, wherein said controlling a number of turns step is further responsive to at least one condition from the group consisting of a temperature of said cell, and a charge current.

15. The method of claim 13, further comprising the step of providing a plurality of taps on said secondary coil, each of said taps providing an electrical connection to said secondary coil.

16. The method of claim 15, further comprising the step of supplying a flow of time-varying electric current through a primary coil of said induction charger to generate a voltage potential between at least two of said plurality of taps.

17. The method of claim 16, further comprising the steps of:

providing at least one switch responsive to a control signal generated by a control circuit; and

signaling said switch to transition between a first position wherein a first voltage is applied from a first of said taps to the corresponding cell coupled to said secondary coil, and a second position wherein a second voltage is applied from a second of said taps to said cell.

18. The method of claim 17, wherein said switch comprises at least one device selected from the group consisting of a transistor, a relay, and a mechanical switch.

19. A method for simultaneously charging a plurality of cells each coupled to a corresponding plurality of secondary coils, comprising the steps of:

placing the plurality of secondary coils and corresponding plurality of cells proximately to a base of an induction charger;

supplying a magnetic flux from said base for charging the plurality of cells;

receiving said magnetic flux at the plurality of secondary coils;

selectively controlling the number of turns of said plurality of secondary coils in response at least in part to a desired voltage to be applied to said plurality of cells; and

generating an output voltage at each of the plurality of secondary coils in response to said received magnetic flux and selectively controlled number of turns of each of said plurality of secondary coils.

20. The method of claim 19, wherein said number of turns step is further responsive to at least one condition from the group consisting of a temperature of said at least one cell, and a charge current.

21. The method of claim 19, wherein the supplying step the magnetic flux is provided by the base having a substantially flat surface.