Battery capacity estimation and control
An automotive power system alters a maximum discharge power of a traction battery according to an estimated capacity of the traction battery that depends on a weight parameter having a value that changes according to a charge experienced by the traction battery during periods when a switch connects the traction battery with an electric machine.
1 . A vehicle comprising:
a traction battery;
an electric machine; and
a controller programmed to alter a maximum discharge power of the traction battery according to an estimated capacity of the traction battery that depends on a previous instantaneous capacity value of the traction battery, a current instantaneous capacity value of the traction battery, and a weight parameter having a value that changes according to a charge experienced by the traction battery and a state of charge of the traction battery.
2 . The vehicle of claim 1 , wherein the value further changes according to the current instantaneous capacity value.
3 . The vehicle of claim 1 further comprising a switch configured to electrically connect the traction battery and the electric machine, wherein the charge corresponds only to periods when the switch is closed.
4 . The vehicle of claim 1 , wherein the weight parameter corresponds to a sample size of a low pass filter.
5 . The vehicle of claim 1 , wherein the estimated capacity is a function of a product of the previous instantaneous capacity value and the weight parameter.
6 . The vehicle of claim 5 , wherein the estimated capacity is also a function of a product of the current instantaneous capacity value and a complement of the weight parameter.
7 . A method comprising:
altering a maximum discharge power of a traction battery according to an estimated capacity of the traction battery that depends on a weight parameter having a value that changes according to a charge experienced by the traction battery during periods when a switch connects the traction battery with an electric machine.
8 . The method of claim 7 , wherein the estimated capacity further depends on a previous instantaneous capacity value of the traction battery and a current instantaneous capacity value of the traction battery.
9 . The method of claim 8 , wherein the estimated capacity is a function of a product of the previous instantaneous capacity value and the weight parameter, and the product of the current instantaneous capacity value and a complement of the weight parameter.
10 . The method of claim 8 , wherein the value further changes according to the current instantaneous capacity value.
11 . The method of claim 7 , wherein the weight parameter corresponds to a sample size of a low pass filter.
12 . An automotive power system comprising:
a controller programmed to alter a maximum discharge power of a traction battery according to an estimated capacity of the traction battery that depends on a weight parameter having a value that changes according to a charge experienced by the traction battery during periods when a switch connects the traction battery with an electric machine.
13 . The automotive power system of claim 12 , wherein the estimated capacity further depends on a previous instantaneous capacity value of the traction battery and a current instantaneous capacity value of the traction battery.
14 . The automotive power system of claim 13 , wherein the estimated capacity is a function of a product of the previous instantaneous capacity value and the weight parameter.
15 . The automotive power system of claim 14 , wherein the estimated capacity is also a function of a product of the current instantaneous capacity value and a complement of the weight parameter.
16 . The automotive power system of claim 13 , wherein the value further changes according to the current instantaneous capacity value.
17 . The automotive power system of claim 12 , wherein the weight parameter corresponds to a sample size of a low pass filter.