Simple and high efficiency balancing circuits and methods for hybrid batteries

Patent metadata

Field	Value
Publication number	US-9787118-B2
Application number	US-201414170033-A
Country	US
Kind code	B2
Filing date	Jan 31, 2014
Priority date	Aug 1, 2011
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A balancing circuits and methods for hybrid batteries having two different rechargeable batteries that are coupled in series includes coupling a fuel gauge to each battery to determine the state of charge of each battery, comparing the state of charge of the two batteries, and if the state of charge of the two batteries is more than a predetermined difference, then enabling a switching converter to source current to a node between the batteries or to sink current from the node between the batteries, as required to tend to equalize the state of charge of the two batteries. Otherwise, if the state of charge of the two batteries is equal within a predetermined allowance, then disabling the switching converter.

First claim

What is claimed is:

1. A balancing circuit for a hybrid battery having at least two different rechargeable batteries coupled in series having one terminal coupled to ground through a sense resistor and one terminal coupled as a battery output of the two batteries comprising:
a plurality of battery voltage based fuel gauges, one coupled to each battery for determining a state of charge of the respective battery;
a logic block coupled to an output of each battery voltage based fuel gauge for determining when the state of charge of the two batteries is different;
a switching converter coupled between the battery output and the ground and being capable of sourcing and sinking current, an input to the switching converter being coupled to an output of the logic block, an output of the switching converter being coupled to a junction between the two batteries without a sense resistor between the switching converter and the junction between the two batteries, the output of the switching converter being responsive to the output of the logic block causing the output of the switching converter to source or sink current as required to keep the two batteries at the same state of charge.

2. The balancing circuit of claim 1 wherein the batteries are of the same chemistries but of different capacities.

3. The balancing circuit of claim 1 wherein the batteries are of different chemistries.

4. The balancing circuit of claim 1 wherein the output of the logic block causes the output of the switching converter to source or sink current as required to keep the two batteries at the same state of charge within a predetermined difference.

5. The balancing circuit of claim 4 wherein the output of the logic block comprises first and second signals, the first signal being an enable signal to enable the switching converter and the second signal being a source/sink signal to cause the output of the switching converter to source or sink current.

6. The balancing circuit of claim 1 wherein the battery voltage based fuel gauges include a Coulomb counter.

7. The balancing circuit of claim 6 wherein the battery voltage based fuel gauges use a battery model.

8. A balancing circuit for a hybrid battery having at least two different rechargeable batteries coupled in series having one terminal coupled to ground and one terminal coupled as a battery output of the two batteries comprising:
a plurality of battery voltage based fuel gauges, one coupled to each battery for determining a state of charge of the respective battery;
a logic block coupled to an output of each battery voltage based fuel gauge for determining when the state of charge of the two batteries is different and providing an output having first and second signals, the first signal being an enable signal to enable a switching converter and the second signal being a source/sink signal to cause an output of the switching converter to source or sink current;
the switching converter coupled between the battery output and the ground and being capable of sourcing and sinking current, inputs to the switching converter being coupled to the output of the logic circuitry, the output of the switching converter being coupled to a junction between the two batteries without a sense resistor between the switching converter and the junction between the two batteries, the output of the switching converter being responsive to the output of the logic block causing the output of the switching converter to source or sink current as required to keep the two batteries at the same state of charge within a predetermined difference.

9. The balancing circuit of claim 8 wherein the batteries are of the same chemistries but of different capacities.

10. The balancing circuit of claim 8 wherein the batteries are of different chemistries.

11. The balancing circuit of claim 8 wherein a sense resistor is coupled in series with the batteries, and wherein the battery voltage based fuel gauges include a Coulomb counter.

12. The balancing circuit of claim 11 wherein the battery voltage based fuel gauges use a battery model.

13. A method of balancing two different batteries that are coupled in series comprising:
coupling a battery voltage based fuel gauge to each battery to determine a state of charge of each battery;
comparing the state of charge of the two different batteries, and
a) if the state of charge of the two different batteries is more than a predetermined difference, then enabling a switching converter to source current to a node between the two different batteries or to sink current from the node between the two different batteries without a sense resistor between the switching converter and the node between the two different batteries, as required to tend to equalize the state of charge of the two different batteries;
b) if the state of charge of the two different batteries is equal within a predetermined allowance, then disabling the switching converter.

14. The method of claim 13 wherein the battery voltage based fuel gauges use a battery model and a Coulomb counter.

15. A balancing circuit for a hybrid battery having at least two different rechargeable batteries coupled in series having one terminal coupled to ground and one terminal coupled as a battery output of the two batteries comprising:
a plurality of voltage based fuel gauges that each use a battery model, one coupled to each battery for determining a state of charge of the respective battery;
a logic block coupled to an output of each battery voltage based fuel gauge for determining when the state of charge of the two batteries is different;
a switching converter coupled between the battery output and the ground and being capable of sourcing and sinking current, an input to the switching converter being coupled to an output of the logic block, an output of the switching converter being coupled to a junction between the two batteries without a sense resistor between the switching converter and the junction between the two batteries, the output of the switching converter being responsive to the output of the logic block to cause the output of the switching converter to source or sink current as required to keep the two batteries at the same state of charge.

16. The balancing circuit of claim 15 wherein the batteries are of the same chemistries but of different capacities.

17. The balancing circuit of claim 15 wherein the batteries are of different chemistries.

18. The balancing circuit of claim 15 wherein the output of the logic block causes the output of the switching converter to source or sink current as required to keep the two batteries at the same state of charge within a predetermined difference.

19. The balancing circuit of claim 18 wherein the output of the logic block comprises first and second signals, the first signal being an enable signal to enable the switching converter and the second signal being a source/sink signal to cause the output of the switching converter to source or sink current.

20. The balancing circuit of claim 15 wherein a sense resistor is coupled in series with the batteries, and wherein the voltage based fuel gauges include a Coulomb counter.

21. A balancing circuit for a hybrid battery having at least two different rechargeable batteries coupled in series having one terminal coupled to ground and one terminal coupled as a battery output of the two batteries comprising:
a plurality of voltage based fuel gauges that each use a battery model, one coupled to each battery for determining a st

Assignees

• Maxim Integrated Products

Inventors

• Wortham Jason Allen

Classifications

• H02J7/54

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

• H02J7/485 Primary

  with provisions for charging different types of batteries · CPC title

• H01M2010/4271

  Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing · CPC title

• H01M10/425

  Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing (printed circuits H05K1/00) · CPC title

• H01M10/4207 Primary

  for several batteries or cells simultaneously or sequentially · CPC title