Apparatus and methods of charging to safe cell voltage

• US 9,673,655 B2
• Filed: 12/31/2014
• Issued: 06/06/2017
• Est. Priority Date: 12/31/2013
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: Bradley, Larry Dean
• Primary Examiner(s): Dunn, Drew A
• Assistant Examiner(s): Thapa, Sailesh
• Application Number:
  US14/587,221
• Publication Number:
  US 20150188329A1
• Time in Patent Office: 888 Days
• Field of Search: 320107
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H02J 7/007 Regulation of charging or discharging current or voltage

Abstract

This document discusses, among other things, a charge regulator configured to optimize charging of an energy storage device by measuring an internal voltage drop of the energy storage device using an open circuit voltage (OCV) across the terminals of the energy storage device during charging and a voltage across the terminals of the energy storage device during charging (CCV).

Claims

1. An apparatus comprising:

a charge regulator configured to receive power from an external source and to control a charging current or voltage to a battery through a first switch;

a first capacitor coupled to a first terminal of the battery through a second switch, the first capacitor configured to sample an open circuit voltage (OCV) of the battery in a first interval;

a second capacitor coupled to the first terminal of the battery through a third switch, the second capacitor configured to sample a voltage of the battery during charging in a second interval; and

an amplifier having a first terminal coupled to the first capacitor and a second terminal coupled to the second capacitor, the amplifier configured to provide an output indicative of the difference between the OCV of the battery and the voltage of the battery during charging,

wherein the charge regulator is configured to control the charging current or voltage to the battery using the output of the amplifier.

2. The apparatus of claim 1, including a summing circuit having a first terminal configured to receive the voltage of the battery during charging and a second terminal configured to receive the output of the amplifier,

wherein the summing circuit is configured to provide a corrected voltage feedback, and

wherein the charge regulator is configured to control the charging current or voltage to the battery using the corrected voltage feedback.

3. The apparatus of claim 2, wherein the summing circuit is coupled to the output of the amplifier through a fourth switch.

4. The apparatus of claim 2, wherein the first terminal of the summing circuit includes a positive terminal and the second terminal of the summing circuit includes a negative terminal.

5. The apparatus of claim 2, wherein the charge regulator is configured to control the charging current or voltage to the battery using the corrected voltage feedback and a reference voltage.

6. The apparatus of claim 1, including a third capacitor coupled to the output of the amplifier through a fourth switch, the third capacitor configured to store the output of the amplifier.

7. The apparatus of claim 1, wherein the first terminal of the amplifier includes an inverting terminal and the second terminal of the amplifier includes a non-inverting terminal.

8. The apparatus of claim 1, wherein the charge regulator is configured to control the charging current or voltage to the battery using the output of the amplifier and a reference voltage.

9. A method comprising:

receiving power from an external source at a charge regulator configured to control a charging current or voltage to a battery through a first switch;

sampling an open circuit voltage (OCV) of the battery using a first capacitor through a second switch in a first interval;

sampling a voltage of the battery during charging using a second capacitor through a third switch in a second interval;

determining a difference between the OCV of the battery and the voltage of the battery during charging using an amplifier;

controlling the charging current or voltage of the charge regulator using the determined difference;

opening the first switch and the third switch and closing the second switch during the first interval; and

opening the second switch and closing the first switch and the third switch during the second interval.

10. The method of claim 9, including:

receiving the voltage of the battery during charging at a first terminal of a summing circuit;

receiving the determined difference between the OCV of the battery and the voltage of the battery during charging at a second terminal of the summing circuit;

determining a corrected voltage feedback using the voltage of the battery during charging and the determined difference; and

wherein the controlling the charging current or voltage of the charge regulator includes using the corrected voltage feedback.

11. The method of claim 10, wherein the receiving the determined difference between the OCV of the battery and the voltage of the battery during charging at the second terminal of the summing circuit includes receiving the determined difference through a fourth switch.

12. The method of claim 10, wherein the first terminal of the summing circuit includes a positive terminal and the second terminal of the summing circuit includes a negative terminal.

13. The method of claim 10, wherein the controlling the charging current or voltage of the charge regulator includes using the corrected voltage feedback and a reference voltage.

14. The method of claim 9, including sampling an output of the amplifier using a third capacitor through a fourth switch in a third interval.

15. The method of claim 9, including:

receiving the OCV of the battery from the first capacitor at an inverting input of the amplifier;

receiving the voltage of the battery during charging from the second capacitor at a non-inverting input of the amplifier.

16. A system comprising:

a charge regulator configured to receive power from an external source and to control a charging current or voltage to a battery through a first switch;

a first capacitor coupled to a first terminal of the battery through a second switch, the first capacitor configured to sample an open circuit voltage (OCV) of the battery in a first interval;

a second capacitor coupled to the first terminal of the battery through a third switch, the second capacitor configured to sample a voltage of the battery during charging in a second interval;

an amplifier having a first terminal coupled to the first capacitor and a second terminal coupled to the second capacitor, the amplifier configured to provide an output indicative of the difference between the OCV of the battery and the voltage of the battery during charging;

a summing circuit having a first terminal configured to receive the voltage of the battery during charging and a second terminal configured to receive the output of the amplifier, the summing circuit configured to provide an output representative of the voltage on the first terminal minus the voltage on the second terminal,

wherein the charge regulator is configured to control the charging current or voltage to the battery using the output of the summing circuit.

17. The system of claim 16, wherein the summing circuit is coupled to the output of the amplifier through a fourth switch.

18. The system of claim 16, including a third capacitor coupled to the output of the amplifier through a fourth switch, the third capacitor configured to store the output of the amplifier.

19. The system of claim 16, wherein the first terminal of the amplifier includes an inverting terminal and the second terminal of the amplifier includes a non-inverting terminal.

20. The apparatus of claim 16, wherein the charge regulator is configured to control the charging current or voltage to the battery using the output of the summing circuit and a reference voltage.