Method and apparatus to charge a battery using determination of battery load current

• US 7,301,307 B2
• Filed: 06/25/2004
• Issued: 11/27/2007
• Est. Priority Date: 06/25/2004
• Status: Expired due to Fees

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Jorgensen, Frank, Hansen, Stig Rafn, Froding, Emil
• Primary Examiner(s): Tso; Edward H
• Application Number:
  US10/876,496
• Publication Number:
  US 20050285568A1
• Time in Patent Office: 1,250 Days
• Field of Search: 320/139, 320/141, 320/144, 320/145
• US Class Current: 320/139
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

By determining charging current I_char and then subsequently utilising that determination of charging current I_char in relation to battery current I_bat and load current I_load as a result of operation of a phone or other electronic device it is possible periodically to adjust the necessary charging current in order to operate the device in terms of recharging the battery to a target charging voltage, as well as providing adequate electrical current for operation of the associated phone or other electronic device.

Claims

1. A battery charging method for a portable hand held device, the method comprising applying a charging current across a battery for charging of the battery to attain a charging voltage and determination of load current by periodic interruption in application of the charging current whereby the charging current for the battery is adjusted towards a defined target value for the charging voltage between determinations of the load current for sustained charging of the battery despite variation in load current requirements.

2. A method as claimed in claim 1 wherein the adjustment towards the defined target value is for consistent battery charging irrespective of load current requirements.

3. A method as claimed in claim 2 wherein charging voltage is maintained up to a pre-determined limit value for the load current.

4. A method as claimed in claim 1 wherein the periodic interruption is in the order of every sixty seconds.

5. A method as claimed in claim 1 wherein the interruption lasts for a time period of one second.

6. A method as claimed in claim 1 wherein the charging current is applied by pulse width modulation (PWM) of that current.

7. A method as claimed in claim 1 wherein the method is only performed upon attainment of a minimum battery charge voltage by the battery for subsequently further charging of the battery to a target value for the charging voltage.

10. A method as claimed in claim 1 wherein the method involves determining the presence of a minimum value of a charging voltage before further charging of the battery to a defined target value of the charging voltage by applying the adjusted charging current.

11. A method as claimed in claim 1 wherein each adjustment of the charging current is dependent upon an immediately previous determination of the load current upon the battery during an interruption.

12. A method as claimed in claim 1 wherein the adjustment of the charging current is dependent upon a number of previous determinations of load current demand upon the battery in respective interruptions in the charging current applied to the battery.

13. A method as claimed in claim 1 wherein the defined target value for the charging voltage is for a desired level of final charging of the battery.

14. A method as claimed in claim 13 wherein the desired level of final charging of the battery is for maximum capacity charging of the battery.

8. A battery charging apparatus comprising means to couple a battery to the apparatus, means to apply a charging current to the battery to attach a charging voltage and means to determine load current by periodic interruption in the application of the charging voltage whereby the charging current is adjusted towards a defined target value for the charging voltage between determinations of the battery load current.

9. A method for charging a battery for a portable hand held device, the method comprising:

(a) applying a charging current to a battery;

(b) interrupting the charging current to determine a value for load current demand upon the battery; and

(c) applying an adjusted charging current to the battery, wherein the adjusted charging current is dependent upon the value of the load current demand upon the battery determined during interruption of the charging current.

22. A method as claimed in claim 9 wherein each adjustment of the charging current is dependent upon an immediately previous determination of the load current upon the battery during an interruption.

23. A method as claimed in claim 9 wherein the adjustment of the charging current is dependent upon a number of previous determinations of load current demand upon the battery in respective interruptions in the charging current applied to the battery.

24. A method as claimed in claim 23 wherein the defined target value for the charging voltage is for a desired level of final charging of the battery.

25. A method as claimed in claim 24 wherein the desired level of final charging of the battery is for maximum capacity charging of the battery.

15. A battery charging apparatus comprising a coupler for coupling a battery to the apparatus, a charger for applying a charging current to a battery, a switch for interrupting the charging current applied to the battery, a sensor for determining a current load demand upon the battery during an interruption in the charging current and a controller for adjusting the charging current in dependence upon a determined current load demand.

16. An apparatus as claimed in claim 15 wherein the controller provides adjustment of the charging current for consistent battery charging irrespective of load current demand over a range of load current demand values by reference to a relationship between a charging voltage, the charging current and the load current demand on the battery stored in the controller.

17. An apparatus as claimed in claim 15 wherein the controller is arranged to limit the charging current to a maximum value so that a charging voltage is maintained up to a pre-determined limit value for the load current demand on the battery during charging of the battery by the charger.

18. An apparatus as claimed in claim 15 wherein the charger is arranged to apply the charging current to the battery by pulse width modulation (PWM) of the charging current applied to the battery.

19. An apparatus as claimed in claim 15 wherein the controller is associated with a charging voltage sensor and arranged to monitor the charging voltage sensor to determine attainment of a minimum charging voltage before the switch provides interruption in the application of the charging current to the battery in order to allow the sensor to determine load current and the controller to adjust the charging current provided by the charger.

20. An apparatus as claimed in claim 15 wherein the switch provides for periodic interruption of the charging current to the battery for determination of the load current demand upon the battery.

27. The apparatus of claim 15, wherein the sensor is additionally configured to detect a voltage at a point in a load current path that is separated from the battery by a known impedance value and wherein the controller is configured to adjust the charging current in dependence upon a target detected voltage determined using the known impedance value and the current load demand.

21. A method of charging a battery, the method comprising applying an input charging current to a battery, interrupting the input charging current to determine a load current output from the battery and controlling the input charging current in dependence upon the determined load current.

28. The method of claim 21, further comprising:

detecting a voltage at a point in a load current path that is separated from the battery by a known impedance value, wherein the input charging current is controlled by determining a target for the detected voltage using the known impedance value and the determined load current; and

adjusting the charging current in dependence upon the target.

26. A method comprising:

(a) applying a charging current to a battery from which current is being drawn as a load current;

(b) interrupting the charging current to determine a value for load current demand upon the battery; and

(c) applying an adjusted charging current to the battery, wherein the adjusted charging current is dependent upon the value of the load current demand upon the battery determined during interruption of the charging current.