METHOD FOR OPERATING A BATTERY SYSTEM, AND BATTERY MANAGEMENT SYSTEM

Abstract

A method for operating a battery system in a vehicle that includes multiple battery units is described. The method includes classifying an instantaneous aging state of the battery units, first association of the battery units with instantaneous aging classes as a function of their instantaneous aging state, predicting a future aging state of the battery units for a future point in time, second association of the battery units with future aging classes as a function of their future aging state, ascertaining an optimal point in time for replacing battery units based on a cost function, taking into account the instantaneous aging classes and the future aging classes. A battery management system that is configured for carrying out the method is also described.

Claims

1. A method for operating a battery system in a vehicle that includes multiple battery units, comprising: classifying an instantaneous aging state of the battery units; first association of the battery units with instantaneous aging classes as a function of their instantaneous aging state; predicting a future aging state of the battery units for a future point in time; second association of the battery units with future aging classes as a function of their future aging state; and ascertaining an optimal point in time for replacing battery units based on a cost function, taking into account the instantaneous aging classes and the future aging classes.

2. The method as recited in claim 1, wherein prior to the first association of the battery units with the instantaneous aging classes, the instantaneous aging classes are stored as historical aging classes.

3. The method as recited in claim 2, wherein the historical aging classes and the instantaneous aging classes are taken into account for predicting the future aging state of the battery units.

4. The method as recited in claim 1, wherein the cost function defines a relationship between maintenance costs to be expected for the replacement of the battery units as a function of a still achievable cruising range of the vehicle.

5. The method as recited in claim 1, wherein the classification of the instantaneous aging state of the battery units takes place at at least one of fixed time intervals and variable time intervals.

6. The method as recited in claim 1, wherein the classification of the instantaneous aging state of the battery units takes place after at least one of a fixed mileage of the vehicle and a variable mileage of the vehicle.

7. The method as recited in claim 1, wherein a display of the battery units that are associated with the particular instantaneous aging class takes place after the first association of the battery units with the instantaneous aging classes.

8. The method as recited in claim 1, wherein a display of the battery units that are associated with the particular future aging class takes place after the second association of the battery units with the future aging classes.

9. A battery management system that is configured to operate a battery system in a vehicle that includes multiple battery units, the battery management system configured to: classify an instantaneous aging state of the battery units; first associate the battery units with instantaneous aging classes as a function of their instantaneous aging state; predict a future aging state of the battery units for a future point in time; second associate the battery units with future aging classes as a function of their future aging state; and ascertain an optimal point in time for replacing battery units based on a cost function, taking into account the instantaneous aging classes and the future aging classes.

10. A method of using a battery system, comprising: proving the battery system in a vehicle, the vehicle including at least one of an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, and an e-bike, classifying an instantaneous aging state of battery units of the battery system; first association of the battery units with instantaneous aging classes as a function of their instantaneous aging state; predicting a future aging state of the battery units for a future point in time; second association of the battery units with future aging classes as a function of their future aging state; and ascertaining an optimal point in time for replacing battery units based on a cost function, taking into account the instantaneous aging classes and the future aging classes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Specific embodiments of the present invention are explained in greater detail with reference to the figures and the description below.

[0030] FIG. 1 shows a schematic illustration of a first association of battery units with instantaneous aging classes.

[0031] FIG. 2 shows a schematic illustration of a second association of battery units with future aging classes.

[0032] FIG. 3 shows an example of a cost function.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0033] In the following description of the specific embodiments of the present invention, identical or similar elements are denoted by the same reference numerals, and a repeated description of these elements is dispensed with in individual cases. The figures illustrate the subject matter of the present invention only in a schematic fashion.

[0034] FIG. 1 shows a schematic illustration of a first association Z1 of battery units 10 with instantaneous aging classes A1, A2, A3, A4, A5. In the present case, battery units 10 are battery modules of a battery system of a vehicle, and themselves include multiple battery cells connected in series. Alternatively, battery units 10 may also represent battery cells. In the specific embodiment described here, five instantaneous aging classes A1, A2, A3, A4, A5 are provided by way of example. However, the number of instantaneous aging classes is variable. Thus, more than five or fewer than five instantaneous aging classes may also be provided.

[0035] According to the present invention, a classification of an instantaneous aging state of all battery units 10 of the battery system initially takes place. In the classification of the instantaneous aging state of battery units 10, various parameters such as in particular the capacity of individual battery units 10 are determined and also evaluated. The actual state of individual battery units 10 of the battery system is thus ascertained by classifying the instantaneous aging state of battery units 10.

[0036] First association Z1 of individual battery units 10 of the battery system with instantaneous aging classes A1, A2, A3, A4, A5 is subsequently carried out. First association Z1 takes place as a function of the particular instantaneous aging state of the particular battery unit 10.

[0037] For this purpose, in the present case a first instantaneous aging class A1, a second instantaneous aging class A2, a third instantaneous aging class A3, a fourth instantaneous aging class A4, and a fifth instantaneous aging class A5 are defined in a battery management system. Each of the instantaneous aging classes A1, A2, A3, A4, A5 represents a stage of aging for battery units 10 of the battery system. As mentioned above, more than five or fewer than five instantaneous aging classes may also be defined.

[0038] Before first association Z1 of battery units 10 with instantaneous aging classes A1, A2, A3, A4, A5 takes place, instantaneous aging classes A1, A2, A3, A4, A5 are stored as historical aging classes. Existing historical aging classes are not discarded, but instead are retained after each first association Z1 of battery units 10 with instantaneous aging classes A1, A2, A3, A4, A5. Thus, historical aging classes are present for each point in time at which a classification of the aging state of battery units 10 has been made. The historical aging classes date back to the manufacture of the battery system.

[0039] In the illustration according to FIG. 1, by way of example one of battery units 10 is associated with third instantaneous aging class A3 with the aid of first association Z1, illustrated as an arrow. After first association Z1 of individual battery units 10 with instantaneous aging classes A1, A2, A3, A4, A5, this results in a distribution of battery units 10 within defined instantaneous aging classes A1, A2, A3, A4, A5, likewise illustrated in FIG. 1.

[0040] After first association Z1 of battery units 10 with instantaneous aging classes A1, A2, A3, A4, A5, a prediction of a future aging state of battery units 10 is made for a future point in time based, for example, on cruising range, operating hours, charge cycles, etc. The probable future state of individual battery units 10 of the battery system is ascertained by predicting the future aging state of battery units 10.

[0041] The historical aging classes and instantaneous aging classes A1, A2, A3, A4, A5 are taken into account for predicting the future aging state of battery units 10 of the battery system. All present, stored historical aging classes are preferably taken into account.

[0042] A second association Z2 of battery units 10 with future aging classes K1, K2, K3, K4, K5 is subsequently carried out as a function of their predicted future aging state. FIG. 2 shows a schematic illustration of second association Z2 of battery units 10 with future aging classes K1, K2, K3, K4, K5. In the specific embodiment described here, five future aging classes K1, K2, K3, K4, K5 are provided by way of example. However, the number of future aging classes is variable. Thus, more than five or fewer than five future aging classes may also be provided.

[0043] For this purpose, in the present case a first future aging class K1, a second future aging class K2, a third future aging class K3, a fourth future aging class K4, and a first future aging class K5 are defined in a battery management system. Each of future aging classes K1, K2, K3, K4, K5 represents a stage of aging for battery units 10 of the battery system. As mentioned above, more than five or fewer than five future aging classes may also be defined.

[0044] In the illustration according to FIG. 2, by way of example multiple battery units 10 are associated with fifth future aging class K5 with the aid of second association Z2 illustrated as an arrow. After second association Z2 of individual battery units 10 with future aging classes K1, K2, K3, K4, K5, this results in a certain distribution of battery units 10 within future aging classes K1, K2, K3, K4, K5, likewise illustrated in FIG. 2.

[0045] An optimal point in time for replacing battery units 10 is subsequently ascertained. The ascertainment of the optimal point in time for replacing battery units 10 takes place based on a cost function F, illustrated by way of example in FIG. 3. Instantaneous aging classes A1, A2, A3, A4, A5 and future aging classes K1, K2, K3, K4, K5 are hereby taken into account.

[0046] Cost function F represents a relationship between maintenance costs W to be expected for the replacement as a function of a still achievable cruising range R of the vehicle. Cost function F allows an ascertainment of a break-even point N.

[0047] Break-even point N indicates whether, and when, a replacement of individual battery units 10 of the battery system or of the entire battery system is more economically meaningful. Break-even point N is used as a guideline for the customer and for a repair shop in order to assess whether a replacement of battery units 10 is meaningful. This may also depend on additional individual, vehicle-specific factors, not mentioned here, which are incorporated in the computation or consideration.

[0048] In the present case, the classification of the instantaneous aging state of battery units 10 as well as the subsequent steps take place at fixed or at variable time intervals, and may thus be carried out periodically.

[0049] Alternatively, the classification of the instantaneous aging state of battery units 10 may be carried out after a fixed mileage or after a variable mileage of the vehicle, and may thus likewise be carried out periodically.

[0050] A display of battery units 10 of the battery system that are associated with fifth instantaneous aging class A5 takes place after first association Z1 of battery units 10 with instantaneous aging classes A1, A2, A3, A4, A5. In the present case, fifth instantaneous aging class A5 represents a critical instantaneous aging class.

[0051] A display of battery units 10 of the battery system that are associated with fifth future aging class K5 takes place after second association Z2 of battery units 10 with future aging classes K1, K2, K3, K4, K5. In the present case, fifth future aging class K5 represents a critical instantaneous [sic; future] aging class.

[0052] In the present case, battery units 10 of the battery system, which are associated with fifth instantaneous aging classes A5 or fifth future aging class K5, are displayed on an onboard computer of the vehicle. A display on a repair shop testing device, on a mobile telephone, on a tablet, on a notebook, or on an infotainment system of the vehicle is also conceivable.

[0053] The present invention is not limited to the exemplary embodiments described here and the aspects highlighted therein. Rather, numerous modifications within the cruising range set forth in the claims are possible which are within the scope of activities carried out by those skilled in the art.