Battery charging pad employing magnetic induction

• US 8,362,744 B2
• Filed: 06/14/2010
• Issued: 01/29/2013
• Est. Priority Date: 06/16/2009
• Status: Expired due to Fees

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Terao, Kyozo, Toya, Shoichi
• Primary Examiner(s): DIAO, M BAYE
• Application Number:
  US12/814,704
• Publication Number:
  US 20100315038A1
• Time in Patent Office: 960 Days
• Field of Search: 320/108, 307/104
• US Class Current: 320/108
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 2310/22 The load being a portable electronic device
• 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 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0045 concerning the insertion or the connection of the batteries

Abstract

A battery charging pad includes a moving mechanism that moves the transmitting coil, and a position detection controller that detects the position of a device housing a battery and controls the moving mechanism to move the transmitting coil in close proximity to a receiving coil. Pulse signals are supplied to a plurality of position detection coils from a pulse generator, and the echo signals are a result of coil excitation by the pulse signals. The battery charging pad position detection controller detects the position of the receiving coil and moves the transmitting coil in close proximity to the receiving coil, and the position detection controller detects the position of the transmitting coil and moves the transmitting coil to the reference position, or it moves the transmitting coil in close proximity to the receiving coil.

Claims

1. A battery charging pad that transmits power from a transmitting coil to a magnetically coupled receiving coil to charge a battery housed in a device housing a battery, comprising:

a transmitting coil disposed in close proximity to the receiving coil in the device housing the battery and configured to transmit electrical power to the receiving coil;

a case configured to house the transmitting coil and including a top plate on which a device housing a battery is placed;

a moving mechanism housed in the case that is configured to move the transmitting coil in close proximity to the receiving coil; and

a position detection controller configured to detect a position of the device housing the battery placed on the top plate and to control the moving mechanism to move the transmitting coil in close proximity to the receiving coil in the device housing the battery;

a capacitor configured to connect to the transmitting coil, the capacitor and the transmitting coil being configured to form a series resonant circuit or a parallel resonant circuit,

wherein the position detection controller comprises;

a plurality of position detection coils fixed to an inside surface of the top plate;

a pulse generator configured to supply pulse signals to the position detection coils;

a receiving circuit configured to receive echo signals output from the receiving coil and a transmitting coil to the position detection coils, as a result of excitation by pulse signals supplied from the pulse generator to the position detection coils; and

a discrimination circuit configured to determine the position of the receiving coil and the transmitting coil from the echo signals received by the receiving circuit,

wherein the position detection controller is configured to detect the position of the receiving coil and transmitting coil when the transmitting coil and the capacitor constitute the parallel resonant circuit, and to control the moving mechanism to move the transmitting coil in close proximity to the receiving coil.

2. The battery charging pad as cited in claim 1, wherein the position detection controller detects transmitting coil position and moves the transmitting coil to an X-axis direction and a Y-axis direction origin (0, 0point).

3. The battery charging pad as cited in claim 2, wherein the position detection controller detects the position of the transmitting coil, and from the detected transmitting coil position, computes the distances in the X-axis direction and Y-axis direction to move the transmitting coil to an origin reference point, and

the position detection controller controls the moving mechanism to move the transmitting coil by the computed distances in the X-axis direction and Y-axis direction towards the origin reference point.

4. The battery charging pad as cited in claim 3, wherein the moving mechanism uses movement distances larger than computed distances to move the transmitting coil to the origin reference point, thereby absorbing moving mechanism slippage at the origin reference point.

5. The battery charging pad as cited in claim 3, wherein the moving mechanism includes servo motors configured move the transmitting coil, and

the transmitting coil is moved to the origin reference point via the servo motors, and after the moving mechanism servo motors rotate to move the transmitting coil from the detected position to the origin reference point, torque is further applied for a given time in a direction to move the transmitting coil toward the origin reference point.

6. The battery charging pad as cited in claim 1, wherein the position detection controller detects a relative position of the transmitting coil with respect to the receiving coil and moves the transmitting coil into close proximity with the receiving coil.

7. The battery charging pad as cited in claim 1, wherein the position detection coils are made up of a plurality of rows of coils, and the position detection coils are fixed at given intervals to the inside surface of the top plate, and

the position detection coils are provided with a plurality of X-axis detection coils that detect transmitting coil and receiving coil position in the X-axis direction, and a plurality of Y-axis detection coils that detect position in the Y-axis direction.

8. The battery charging pad as cited in claim 7, wherein the plurality of X-axis detection coils are shaped as long narrow loops extending in the Y-axis direction and fixed to the inside surface of the top plate at given intervals, and

the plurality of Y-axis detection coils are shaped as long narrow loops extending in the X-axis direction and fixed to the inside surface of the top plate at given intervals.

9. The battery charging pad as cited in claim 8, wherein an interval (d) between adjacent X-axis detection coils is smaller than an outside diameter (D) of the receiving coil and smaller than an outside diameter (W) of the transmitting coil, and

the interval (d) between adjacent Y-axis detection coils is smaller than the outside diameter (D) of the receiving coil and smaller than the outside diameter (W) of the transmitting coil.

10. The battery charging pad as cited in claim 1, wherein a switching circuit is provided between the transmitting coil and the AC power source, the switching circuit connecting the transmitting coil to the AC power source to supply AC power to the transmitting coil from the AC power source, and

the switching circuit configures both sides of an output at ground potential to detect transmitting coil position.

11. The battery charging pad as cited in claim 10, wherein the capacitor is connected in parallel with the transmitting coil to form the parallel resonant circuit, and the switching circuit grounds both sides of the output to form the parallel resonant circuit with the capacitor and transmitting coil for detection of the transmitting coil position.

12. The battery charging pad as cited in claim 10, wherein the switching circuit includes an input circuit that grounds both sides of the output, and both sides of the switching circuit output are configured to be at ground potential by a control signal input from the input circuit.

13. The battery charging pad as cited in claim 12, wherein the switching circuit includes a full-bridge output circuit connected to the output-side of the AC power source, and the AC power source is configured to have the full-bridge output circuit connected to the output-side of an oscillator circuit to supply AC power to the transmitting coil.

14. The battery charging pad as cited in claim 1, wherein the AC power source includes an oscillator circuit, and an output of the oscillator circuit AC is amplified by a full-bridge output circuit and supplied to the transmitting coil.

15. The battery charging pad as cited in claim 10, wherein the switching circuit includes a full-bridge output circuit connected to the output-side of the AC power source, a voltage signal is input to the full-bridge output circuit to ground the output side, and both sides of the switching circuit output are configured to be at ground potential to detect transmitting coil position.

16. The battery charging pad as cited in claim 1, wherein the capacitor is connected in parallel with the transmitting coil to form the parallel resonant circuit,

a capacitance C1 of the capacitor is a different value than a capacitance C2 of the capacitor connected in parallel with the receiving coil to form a parallel resonant circuit in the device housing the battery, and

the position detection controller distinguishes the position of the transmitting coil and the receiving coil using different delay times of the echo signals output to the position detection coils from the transmitting coil and the receiving coil.

17. The battery charging pad as cited in claim 16, wherein the capacitor is connected in parallel with the transmitting coil to form the parallel resonant circuit,

a capacitance C1 of the capacitor is larger than a capacitance C2 of the capacitor connected in parallel with the receiving coil to form the parallel resonant circuit in the device housing the battery, and

the position detection controller distinguishes the position of the transmitting coil and the receiving coil using different delay times of the echo signals output to the position detection coils from the transmitting coil and the receiving coil.

18. The battery charging pad as cited in claim 1, wherein the position detection controller includes a first position detection controller that is configured to detect the position of the transmitting coil and the position of the receiving coil, and a second position detection controller that is configured to detect the position of the receiving coil with high precision, and

the first position detection controller includes position detection coils.

19. The battery charging pad as cited in claim 18, wherein the second position detection controller detects receiving coil position by either an oscillating frequency of the AC power source, a transmitting coil voltage, AC power source power consumption, or a receiving coil current.

20. the battery charging paid as cited in claim 1, wherein the transmitting coil is configured to transmit the electric power to the receiving coil when the transmitting coil and the capacitor constitute the series resonant circuit.