Estimation of battery power capability in a torque-generating system

Patent metadata

Field	Value
Publication number	US-10101402-B2
Application number	US-201615168742-A
Country	US
Kind code	B2
Filing date	May 31, 2016
Priority date	May 31, 2016
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

A method for estimating battery power capability in a torque-generating system having a battery pack with battery cells includes calculating a voltage spread as a difference between an average and minimum cell voltage of the battery pack. The method also includes increasing a calibrated voltage control limit by an offset that is based on a magnitude of the voltage spread, doing so when the minimum cell voltage is less than the control limit, and recording the offset in a memory location referenced by pack operating conditions. Further, the power capability is estimated using the recorded offset when the battery pack operates under conditions that are the same as the operating conditions, and then executing a control action of the system using the estimated power capability. A torque-generating system includes the battery pack, an electric machine, and a controller programmed to execute the above-described method.

First claim

The invention claimed is:

1. A method for estimating battery power capability in a torque-generating system having a battery pack with a plurality of battery cells, the method comprising:
calculating a voltage spread via a controller as a difference between an average and a minimum cell voltage of the battery pack;
increasing a calibrated voltage control limit by an offset that is based on a magnitude of the voltage spread when the minimum cell voltage is less than the calibrated voltage control limit;
recording the offset in a memory location of the controller that is referenced by operating conditions of the battery pack;
estimating a power capability of the battery pack, using the recorded offset, when the battery pack is operating under conditions that are the same as the operating conditions; and
executing, via the controller, a control action of the torque-generating system using the estimated power capability.

2. The method of claim 1 , wherein the operating conditions of the battery pack include a state of charge or a temperature of the battery pack.

3. The method of claim 2 , wherein the operating conditions of the battery pack include the state of charge and the temperature of the battery pack.

4. The method of claim 1 , further comprising measuring a cell voltage for each of the battery cells using a voltage sensor.

5. The method of claim 1 , wherein estimating a power capability of the battery pack includes estimating each of a maximum charging power capability and a maximum discharging power capability over a plurality of different future time windows.

6. The method of claim 1 , wherein increasing the calibrated voltage control limit occurs only when the magnitude of the voltage spread exceeds a calibrated voltage spread threshold.

7. The method of claim 1 , wherein the torque-generating system includes an engine, and wherein the control action includes commanding the engine to turn on or off.

8. The method of claim 1 , wherein the torque-generating system is a vehicle, and wherein the control action includes executing a route planning action of the vehicle.

9. The method of claim 1 , wherein estimating the power capability of the battery pack using the recorded offset includes adjusting a voltage of the battery pack by an amount that is proportional to the magnitude of the voltage spread, and then calculating the power capability using the adjusted voltage.

10. A torque-generating system comprising:
a battery pack having a plurality of battery cells;
an electric machine operable for generating output torque when supplied with electricity from the battery pack; and
a controller in communication with the battery pack, wherein the controller is programmed to:
calculate a voltage spread as a difference between an average and a minimum cell voltage of the battery pack;
increase a calibrated voltage control limit by an offset that is based on a magnitude of the voltage spread when the minimum cell voltage is less than the calibrated voltage control limit;
record the offset in a memory location of the controller that is referenced by operating conditions of the battery pack;
estimate a power capability of the battery pack, using the recorded offset, when the battery pack is operating under conditions that are the same as the operating conditions; and
execute a control action of the torque-generating system using the estimated power capability.

11. The torque-generating system of claim 10 , further comprising a set of drive wheels connected to the electric machine, wherein the torque-generating system is a vehicle having an electrified powertrain that includes the electric machine.

12. The torque-generating system of claim 10 , wherein the operating conditions of the battery pack include a state of charge or a temperature of the battery pack.

13. The torque-generating system of claim 12 , wherein the operating conditions of the battery pack include the state of charge and the temperature of the battery pack.

14. The torque-generating system of claim 10 , further comprising a plurality of voltage sensors each operable for measuring a cell voltage for a corresponding one of the battery cells.

15. The torque-generating system of claim 10 , wherein the controller is programmed to estimate the power capability of the battery pack by estimating each of a maximum charging power capability and a maximum discharging power capability over a plurality of different future time windows.

16. The torque-generating system of claim 10 , wherein the controller is programmed to increase the calibrated voltage control limit occurs only when the magnitude of the voltage spread exceeds a calibrated voltage spread threshold.

17. The torque-generating system of claim 10 , further comprising an engine, wherein the controller is programmed to command the engine to turn on or off as the control action.

18. The torque-generating system of claim 10 , wherein the torque-generating system is a vehicle, and wherein the controller is programmed to execute a route planning action of the vehicle as the control action.

19. The torque-generating system of claim 10 , wherein the controller is programmed to estimate the power capability of the battery pack using the recorded offset by adjusting a voltage of the battery pack by an amount that is proportional to the magnitude of the voltage spread, and then calculating the power capability using the adjusted voltage.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Frost Patrick E
• Fraga Rory B
• Laskowsky Patricia M
• Suttman Alexander K

Classifications

• B60W20/13

  in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion · CPC title

• G01R31/367 Primary

  Software therefor, e.g. for battery testing using modelling or look-up tables · CPC title

• G01R31/382

  Arrangements for monitoring battery or accumulator variables, e.g. SoC · CPC title

• B60L58/10

  for monitoring or controlling batteries · CPC title

• B60L11/1851

  Operations & Transport · mapped topic