Control of current in parallel battery strings

Patent metadata

Field	Value
Publication number	US-10109899-B1
Application number	US-201715473684-A
Country	US
Kind code	B1
Filing date	Mar 30, 2017
Priority date	Mar 30, 2017
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

A battery assembly has a first battery string including a first plurality of cells connected in series. A second battery string is connected in parallel to the first battery string and includes a second plurality of cells connected in series. A fluid channel is operatively connected to the first and the second battery strings and includes a fluid flowing within. A controller is operatively connected to the first and the second battery strings. The controller is configured to determine a desired temperature differential between the first and the second temperatures of the battery strings based at least partially on a respective strength status of the first and the second battery strings. The controller is configured to control the first and the second currents, via the fluid in the fluid channel, based at least partially on the desired temperature differential.

First claim

What is claimed is:

1. A battery assembly comprising:
a first battery string including a first plurality of cells connected in series, the first battery string operable at a first temperature and configured to produce a first current;
a second battery string connected in parallel to the first battery string and including a second plurality of cells connected in series, the second battery string being operable at a second temperature and configured to produce a second current;
a fluid channel having a fluid flowing within, the fluid channel being operatively connected to the first and the second battery strings;
a controller operatively connected to the first and the second battery strings;
wherein the controller includes a processor and tangible, non-transitory memory on which is recorded instructions, execution of the instructions by the processor causing the controller to:
determine respective strength status of the first and the second battery strings;
determine a desired temperature differential between the first and the second temperatures based at least partially on the respective strength status;
control the first and the second currents, via the fluid in the fluid channel, based at least partially on the desired temperature differential.

2. The assembly of claim 1 , wherein the respective strength status of the first and the second battery strings includes at least one of a state of health, resistance and a capacity.

3. The assembly of claim 1 , further comprising:
a heating unit operatively connected to the fluid channel and configured to warm a portion of the fluid to produce a warming fluid; and
a cooling unit operatively connected to the fluid channel and configured to cool another portion of the fluid to produce a cooling fluid.

4. The assembly of claim 3 , further comprising:
a first mixer operatively connected to the fluid channel and configured to mix the warming fluid and the cooling fluid in a first proportion to make a first thermal mixture;
a second mixer operatively connected to the fluid channel and configured to mix the warming fluid and the cooling fluid in a second proportion to make a second thermal mixture;
wherein the controller is configured to command the first mixer to direct the first thermal mixture to pass through the first battery string such that heat transfer between the first thermal mixture and the first battery string is enabled; and
wherein the controller is configured to command the second mixer to direct the second thermal mixture to pass through the second battery string such that heat transfer between the second thermal mixture and the second battery string is enabled.

5. The assembly of claim 4 , further comprising:
at least one sensor operatively connected to the controller and configured to provide sensor feedback; and
wherein the controller is configured to adjust the first and the second proportions based on the sensor feedback.

6. The assembly of claim 5 , wherein:
the at least one sensor includes a first and a second current sensor configured to measure the first and second currents, respectively; and
the controller includes a closed loop control unit receiving the sensor feedback from the first and the second current sensor.

7. The assembly of claim 5 , wherein:
the controller is configured to allow a maximum power extracted from the first and the second battery string; and
the controller is configured to adjust the first and the second proportions such that the first current and the second current converge.

8. The assembly of claim 5 , wherein:
the first and the second battery strings define a first strength status and a second strength status, respectively; and
the controller is configured to adjust the first and the second proportions such that the first current is proportional to the first strength status and the second current is proportional to the second strength status.

9. The assembly of claim 5 , wherein the controller includes a thermal management unit configured to:
control the first proportion such that the first temperature is within a first range defined by a first maximum and a first minimum; and
control the second proportion such that the second temperature is within a second range defined by a second maximum and a second minimum.

10. The assembly of claim 4 , further comprising:
a first housing configured to enclose the first battery string;
wherein the fluid channel includes a first portion configured to extend through an interior of the first housing, the first thermal mixture being configured to flow through the first portion;
a second housing configured to enclose the second battery string; and
wherein the fluid channel includes a second portion configured to extend through an interior of the second housing, the second thermal mixture being configured to flow through the second portion.

11. The assembly of claim 10 , wherein:
the first portion and the second portion each define a substantially sinusoidal shape.

12. The assembly of claim 3 , further comprising:
a pump configured to provide the fluid to the fluid channel;
wherein the heating unit includes a first condenser directly connected to the pump;
wherein the cooling unit includes an evaporator directly connected to the pump;
an auxiliary circuit configured to circulate an auxiliary substance between the heating unit and the cooling unit such that the auxiliary substance is in thermal communication with the fluid but does not physically mix; and
wherein the auxiliary circuit includes a compressor and a second condenser.

13. A method for controlling a first current produced by a first battery string and a second current produced by a second battery string, in an assembly having a fluid channel with a fluid flowing within, a heating unit, a cooling unit, a first mixer, a second mixer, a controller and at least one sensor, the first battery string and the second battery string being connected in parallel, operable at first and second temperatures, respectively, the method comprising:
determining respective strength status of the first and the second battery strings, via the controller;
determining a desired temperature differential between the first and the second temperatures based at least partially on the respective strength status and respective target currents for the first and second battery strings, via the controller;
warming a portion of the fluid, via the heating unit, to produce a warming fluid;
cooling another portion of the fluid, via the cooling unit, to produce a cooling fluid;
mixing the warming fluid and the cooling fluid in a first proportion, via the first mixer, to make a first thermal mixture;
mixing the warming fluid and the cooling fluid in a second proportion, via the second mixer, to make a second thermal mixture;
determining the first proportion and the second proportion based at least partially on the desired temperature differential; and
controlling the first and second currents by commanding the first mixer to direct the first thermal mixture through the first battery string in order to allow heat transfer between the first thermal mixture and the first battery string, and commanding the second mixer to direct the second thermal mixture through the second battery string in order to allow heat transfer between the second thermal mixture and the second battery string.

14. The method of claim 13 , further comprising:
obtaining sensor feedback from the at least one sensor; and
adjusting the first and the second proportions based on the sensor feedback such that the first current and the second current converge.

Assignees

• Gm Global Tech Operations Llc
• Spiers New Tech Inc

Inventors

• Karlson Peter T
• Schultz Bryan
• Maxwell David S

Classifications

• H01M10/48

  Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569) · CPC title

• H01M10/486

  for measuring temperature · CPC title

• H01M50/204

  Racks, modules or packs for multiple batteries or multiple cells · CPC title

• H01M2/1077

  Electricity · mapped topic

• H01M10/613

  Cooling or keeping cold · CPC title