Device and method for charging a battery

• US 9,455,587 B2
• Filed: 05/27/2014
• Issued: 09/27/2016
• Est. Priority Date: 10/11/2013
• Status: Active Grant

• Current Assignee: Dialog Semiconductor GmbH (Renesas Electronics Corporation)
• Original Assignee: Dialog Semiconductor GmbH (Renesas Electronics Corporation)
• Inventors: Schumacher, Otto, Girard, Olivier, Martins, Joao Paulo Trierveiler, Sturm, Hartmut, Rigoni, Fabio
• Primary Examiner(s): Kik, Phallaka
• Application Number:
  US14/287,358
• Publication Number:
  US 20150102779A1
• Time in Patent Office: 854 Days
• Field of Search: 320/139, 320/141, 320/145, 320/162
• US Class Current: 1/1
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices

Abstract

A method for charging a battery is provided, wherein current pulses are supplied to the battery, wherein each pulse is followed by a rest period during which no current is supplied to the battery, and wherein the state of charge of the battery is determined during the rest period.

Claims

1. A method for charging a battery comprising:

supplying current pulses to the battery, wherein each pulse is followed by a rest period during which no current is supplied to the battery;

determining the state of charge of the battery during the rest period;

comparing, using an analog comparator, the battery voltage to the predetermined voltage threshold; and

measuring a relaxation time from the start of the rest period until the time at which the analog comparator determines that the battery voltage has reached the predetermined voltage threshold.

2. The method according to claim 1, further comprising:

measuring the battery voltage during a rest period between two pulses; and

determining that the battery is fully charged if the measured battery voltage is higher than or equal to a predetermined voltage threshold.

3. The method according to claim 2, further comprising:

determining a pulse duration of a pulse of constant current or a charging current according to the battery voltage measured in the rest period preceding the pulse.

4. The method according to claim 3, wherein the pulse duration is set according to a difference between the measured battery voltage in the rest period preceding the pulse and the predetermined voltage threshold.

5. The method according to claim 2, wherein the battery voltage is measured towards the end of a rest period.

6. The method according to claim 2, wherein the battery voltage is recorded during the rest period, and wherein a relaxation time is determined, which relaxation time corresponds to the time from the start of the rest period until the battery voltage drops below the predetermined voltage threshold.

7. The method according to claim 6, wherein the pulse duration and/or the charging current is set according to an inverse relation to the determined relaxation time.

8. The method according to claim 2, wherein a constant current is supplied continuously to the battery during a first charging phase, until the measured battery voltage during the current supply reaches the predetermined voltage threshold, and wherein the current pulses are supplied to the battery in a second charging phase, wherein each pulse is followed by a rest period during which no current is supplied to the battery.

9. The method according to claim 1 wherein the battery is a charge storage device.

10. The method according to claim 9 wherein the battery is a capacitor.

11. A battery charging device, comprising:

a power supply unit adapted to supply a constant current to a battery at a predetermined current value;

a control unit adapted to control the current supply to the battery such that current pulses are supplied to the battery, wherein each pulse is followed by a rest period during which no current is supplied to the battery, and wherein the control unit is further adapted to determine the state of charge of the battery during the rest period,

wherein the control unit further comprises an analog comparator for comparing the battery voltage to the predetermined voltage threshold, wherein the control unit is further adapted to measure a relaxation time from the start of the rest period until the time at which the analog comparator determines that the battery voltage has reached the predetermined voltage threshold.

12. The battery charging device according to claim 11, wherein the control unit is further adapted to measure the battery voltage during a rest period between two pulses and to determine that the battery is fully charged if the measured battery voltage is higher than or equal to a predetermined voltage threshold.

13. The battery charging device according to claim 12, wherein the control unit is further adapted to determine a pulse duration of a pulse of constant current and/or a charging current according to the battery voltage measured in the rest period preceding the pulse.

14. The battery charging device according to claim 12, wherein the control unit further comprises an analog-to-digital converter (ADC) for measuring the battery voltage, wherein the control unit is adapted to perform the voltage measurement with the ADC converter at the end of a rest period and to determine a voltage difference between the measured battery voltage and the predetermined voltage threshold.

15. The battery charging device according to claim 14, wherein the control unit is further adapted to determine a pulse duration of a pulse of constant current and/or a charging current according to the voltage difference determined in the rest period preceding the pulse.

16. The battery charging device according to claim 15, wherein the control unit is further adapted to set the pulse duration and/or the charging current according to an inverse relation to the determined relaxation time.

17. The battery charging device according to claim 16, wherein said inverse function is inversely proportional to the measured time Δ

_tn such that T_n=k/Δ

_tn, wherein k is a constant, T_n is duration of a pulse of constant current, and measured time Δ

_tn.

18. The battery charging device according to claim 17 wherein the measured time Δ

_tn will be inversely related to the voltage difference Δ

_Vn between the actual battery voltage and the target battery voltage.

19. The battery charging device according to claim 11 wherein said battery is a charge storage device.

20. The battery charging device according to claim 19 wherein said charge storage device said is a capacitor.

21. The battery charging device according to claim 19 wherein said charge storage device is a rechargeable battery.

22. The battery charging device according to claim 19 wherein said charge storage device is a Li ion battery.