Balanced battery charging system

Patent metadata

Field	Value
Publication number	US-10283973-B2
Application number	US-201715483685-A
Country	US
Kind code	B2
Filing date	Apr 10, 2017
Priority date	Apr 11, 2016
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

A multi-cell battery pack charging system adjusts each battery cell's charging current to synchronize the completion of charge. The battery pack is charged as a whole, and need only be charged once, and without requiring charge shuttling, resistive charge balancing or inductive charge dumping. Charging current to each battery cell is based on voltage matching of the battery cells being charged, lower voltage battery cells being given more charge current until there is a voltage match to the other series connected battery cells. Additional charge may be given to higher capacity cells of the battery pack during the voltage matching and charging process.

First claim

The invention claimed is:

1. A battery charging system for charging a plurality of series connected battery cells in a battery pack, said system comprising:
a first electrical connector adapted for coupling to a second electrical connector of a battery pack, said battery pack comprising a plurality of battery cells coupled in series, wherein each electrical node of the plurality of battery cells is coupled to a respective one of a plurality of electrical contacts of the second electrical connector;
a first power supply having voltage set-point and a current limit input, where plus and minus outputs from the first power supply are coupled to respective electrical contacts of the first electrical connector that match plus and minus electrical contacts of the second connector that include all of the plurality of battery cells connected in series;
a plurality of second power supplies, each having voltage set-point and a current limit input, where plus and minus outputs from each of the plurality of second power supplies is coupled to associated ones of the plurality of battery cells, wherein each one of the plurality of second power supplies can supply charging current to only the one battery cell associated therewith;
voltage measurement means configured to measure voltages of each of the plurality of battery cells; and
a charge control unit configured to charge the series connected plurality of battery cells with the first power supply and upon detection of a difference between battery cell voltages to individually charge battery cells having a lower voltage than the other battery cells with additional charging current from the associated ones of the plurality of second power supplies, wherein the first power supply charging current is reduced by the amount of the charging current from the second power supply.

2. The battery charging system according to claim 1 , wherein the voltage measurement means comprises a plurality of analog-to-digital converters (DACs) coupled to voltage nodes of the series coupled plurality of battery cells.

3. The battery charging system according to claim 1 , wherein the voltage measurement means comprises an analog-to-digital converter (ADC) and a multiplexer coupled between the voltage nodes of the series coupled plurality of battery cells and the ADC.

4. The battery charging system according to claim 1 , wherein the first power supply is a high current switched-mode power supply, and the plurality of second power supplies are isolated flyback switched mode power supplies.

5. The battery charging system according to claim 1 , wherein a microcontroller provides:
voltage set-point and current limit signals to the first power supply and the plurality of second power supplies;
the voltage measurement means for measuring voltage of each of the plurality of battery cells; and
a digital processor and memory for running battery charging programs and controlling the first power supply voltage set-point and current limit, and controlling the plurality of second power supplies voltage set-points and current limits.

6. The battery charging system according to claim 5 , further comprising a microcontroller communications port coupled to the digital processor for providing battery charging profiles and battery charging status.

7. The battery charging system according to claim 1 , wherein the plurality of battery cells are Lithium-ion (Li-Ion) battery cells.

8. The battery charging system according to claim 1 , wherein the plurality of battery cells are a plurality of Lithium-ion (Li-ion) battery cells.

9. The battery charging system according to claim 1 , wherein the plurality of battery cells are selected from the group consisting of sealed lead acid, NiMh, and NiCad.

10. A battery charging system for charging two series connected battery cells in a battery pack, said system comprising:
a first electrical connector adapted for coupling to a second electrical connector of a battery pack, said battery pack comprising first and second battery cells coupled in series, wherein each electrical node of the first and second battery cells is coupled to a respective one of a plurality of electrical contacts of the second electrical connector;
a first power supply having a voltage set-point and a current limit input, where plus and minus outputs from the first power supply are coupled to respective electrical contacts of the first electrical connector that match plus and minus electrical contacts of the second connector that include both of the first and second battery cells connected in series;
a second power supply having a voltage set-point and a current limit input, where plus and minus outputs from the second power supply are coupled only to the first battery cell;
a third power supply having a voltage set-point and a current limit input, where plus and minus outputs from the third power supply are coupled only to the second battery cell;
voltage measurement means configured to measure voltages of the first and second battery cells; and
a charge control unit configured to charge the series connected first and second battery cells with the first power supply and upon detection of a difference between the first and second battery cell voltages to individually charge the battery cell having a lower voltage than the other battery cell with additional charging current from the associated second or third power supply, wherein the first power supply charging current is reduced by the amount of the charging current from the second or third power supply.

11. The battery charging system according to claim 10 , wherein the voltage measurement means comprises at least two analog-to-digital converters (DACs) coupled to voltage nodes of the series coupled first and second battery cells.

12. The battery charging system according to claim 10 , wherein the voltage measurement means comprises an analog-to-digital converter (ADC) and a multiplexer coupled between the voltage nodes of the series coupled first and second battery cells and the ADC.

13. The battery charging system according to claim 10 , wherein the first power supply is a high current switched-mode power supply, and the second and third power supplies are isolated flyback switched mode power supplies.

14. The battery charging system according to claim 10 , wherein a microcontroller provides:
voltage set-point and current limit signals to the first, second and third power supplies;
the voltage measurement means for measuring voltages of the first and second battery cells; and
a digital processor and memory for running battery charging programs and controlling the first, second and third power supply voltage set-points and current limits.

15. The battery charging system according to claim 14 , further comprising a microcontroller communications port coupled to the digital processor for providing battery charging profiles and battery charging status.

16. A method for charging a battery pack comprising a plurality of battery cells, said method comprising the steps of:
providing a first electrical connector adapted for coupling to a second electrical connector of the battery pack, said battery pack comprising a plurality of battery cells coupled in series, wherein each electrical node of the plurality of battery cells is coupled to a respective one of a plurality of electrical contacts of the second electrical connector;
providing a first power supply having voltage set-point and a current limit input, where plus and minus outputs from the first power supply are coupled to respective electrical contacts of the first electrical connector t

Assignees

• Microchip Tech Inc

Inventors

• Curtis Keith

Classifications

• H02J7/54

  Passive balancing, e.g. using resistors or parallel MOSFETs · CPC title

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/82

  Control of state of charge [SOC] · CPC title

• H02J7/56

  Active balancing, e.g. using capacitor-based, inductor-based or DC-DC converters · CPC title

• H02J7/52

  for charge balancing, e.g. equalisation of charge between batteries · CPC title