Battery pack, battery powered device, and contactless charging method

• US 9,018,900 B2
• Filed: 07/27/2012
• Issued: 04/28/2015
• Est. Priority Date: 07/28/2011
• Status: Active Grant

• Current Assignee: Panasonic Energy (Shanghai) Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamamoto, Hiroyoshi, Itagaki, Shinichi
• Primary Examiner(s): Dinh, Paul
• Assistant Examiner(s): AISAKA, BRYCE M
• Application Number:
  US13/560,000
• Publication Number:
  US 20130026984A1
• Time in Patent Office: 1,005 Days
• Field of Search: 320/108
• US Class Current: 320/108
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/0044 specially adapted for holding portable devices containing batteries H02J7/0045 takes precedence
• CPC Class Codes: H02J 7/00716 in response to integrated charge or discharge current

Abstract

A battery pack having a contactless charging circuit (95) that rectifies power received by a receiving coil (1), and a battery pack control section (91) with a connection decision section. The battery pack control section (91) is configured to judge whether or not the battery pack is connected to the body of a battery powered device (101) based on the rectified voltage of the contactless charging circuit (95). This decision utilizes the fact that the charging circuit is in a no-load condition and the rectified voltage is high when the battery pack is not connected to the battery powered device, and allows reliable judgment of whether or not the battery pack (90) is attached to the battery powered device.

Claims

1. A battery pack to be connected to the body of a battery powered device to supply power to drive the battery powered device which is capable of displaying remaining battery capacity, the battery pack comprising:

a rechargeable battery cell;

a receiving coil that can magnetically couple with a transmitting coil housed in a charging pad;

a charging current path formed by a charging circuit that converts power received by the receiving coil from the transmitting coil to charge the rechargeable battery cell;

a connection decision section to determine whether the battery pack is alone or connected with the body of the battery powered device;

a current path switch connected with the charging circuit and controlled based on decisions by the connection decision section to close when the battery pack is alone and to open when the battery pack is connected with the body of the battery powered device;

a contactless charging circuit that rectifies power induced in the receiving coil; and

a battery pack control section that includes the connection decision section, wherein the battery pack control section is configured to judge whether or not the body of the battery powered device is connected based on a voltage rectified by the contactless charging circuit.

2. The battery pack as cited in claim 1 wherein the battery pack is capable of changing the charging current path to allow transmission of information related to the remaining charge capacity of the rechargeable battery cell to the body of the battery powered device.

3. The battery pack as cited in claim 1, wherein the battery pack control section controls the current path switch open and closed.

4. The battery pack as cited in claim 3 wherein the connection decision section compares the voltage rectified by the contactless charging circuit with a set threshold voltage, and

wherein the battery pack is judged as connected with the body of the battery powered device when the rectified voltage is below the threshold voltage;

and the battery pack is judged as unconnected when the rectified voltage is greater than the threshold voltage.

5. The battery pack as cited in claim 4 wherein the threshold voltage is set higher than the full-charge voltage of the rechargeable battery cell.

6. The battery pack as cited in claim 1 wherein the initial state of the current path switch is set to the open condition.

7. The battery pack as cited in claim 1 further comprising an adapter decision section to determine whether or not the battery pack is connected to the body of a battery powered device receiving power from an AC/DC adapter connected to an external source of commercial power.

8. The battery pack as cited in claim 7, further comprising:

a data terminal that connects with DC supply voltage from the AC/DC adapter or with a voltage converted from that supply voltage, wherein the battery pack control section acting as the adapter decision section uses the data terminal to determine whether or not the AC/DC adapter is connected.

9. A battery powered device provided with a battery pack, and a body of the battery powered device that is driven by power supplied from the connected battery pack and is capable of displaying the remaining capacity of the battery pack;

the battery pack comprising;

a rechargeable battery cell;

a receiving coil that can magnetically couple with a transmitting coil housed in a charging pad;

a charging current path formed by a charging circuit that converts power received by the receiving coil from the transmitting coil to charge the rechargeable battery cell;

a connection decision section to determine whether the battery pack is alone or connected with the body of the battery powered device;

a current path switch connected with the charging circuit and controlled based on decisions by the connection decision section to close when the battery pack is alone and to open when the battery pack is connected with the body of the battery powered device;

a contactless charging circuit that rectifies power induced in the receiving coil; and

a battery pack control section that includes the connection decision section, wherein the battery pack control section is configured to judge whether or not the body of the battery powered device is connected based on a voltage rectified by the contactless charging circuit.

10. The battery powered device as cited in claim 9 wherein the battery powered device communicates data related to the remaining charge capacity of the rechargeable battery cell with the body of the battery powered device by changing the charging current path.

11. The battery powered device as cited in claim 9 wherein the body of the battery powered device comprises a remaining capacity computation section connected with the charging circuit that can compute rechargeable battery cell remaining capacity during rechargeable battery cell charging by integrating current or power due to current flowing through the charging current path established by the charging circuit.

12. The battery powered device as cited in claim 9 wherein the remaining capacity computation section comprises a charging current detection resistor to detect the current that charges the rechargeable battery cell.

13. The battery powered device as cited in claim 9 wherein current is detected by a charging current detection resistor inside the battery powered device when the current path switch is in the open state.

14. A battery pack contactless charging method that places the battery pack on a charging pad, magnetically couples a receiving coil housed in the battery pack with a transmitting coil in the charging pad, and transmits power from the charging pad to the battery pack to charge the rechargeable battery cell inside the battery pack;

the method comprising;

placing the battery pack on the charging pad;

rectifying power induced in the receiving coil;

activating a battery pack control section, and opening a current path switch;

detecting a voltage rectified in the receiving coil and determining whether or not the battery pack is attached to the body of a battery powered device based on the detected voltage by using the battery pack control section; and

opening the current path switch to change the charging current path with the battery pack control section when the battery pack is determined to be attached to the body of the battery powered device.

15. The battery pack contactless charging method as cited in claim 14 wherein the system is configured to communicate data related to rechargeable battery cell remaining capacity with the body of the battery powered device by changing the charging current path.

16. The battery pack contactless charging method as cited in claim 14 further comprises determining whether or not the battery pack is connected to the body of a battery powered device receiving power from an AC/DC adapter connected to an external commercial power source, to begin contactless charging when the AC/DC adapter is judged as not connected, and to suspend contactless charging when the AC/DC adapter is judged as connected.

17. The battery pack contactless charging method as cited in claim 14 wherein current is detected by a charging current detection resistor inside the battery powered device when the current path switch is in the open state.