Method for operating an electrical energy store of an electrically operable motor vehicle

#The invention relates to a device and a method for operating an electrical energy store, in particular for supplying power to components of an electrically operable motor vehicle, such as, for example, a battery electric vehicle (BEV) or a hybrid electric vehicle (HEV), which can be driven either by an internal combustion engine and/or an electric drive.

#For an electrical energy store, which is used for supplying power to an electrical machine and is also referred to as a traction battery or high-voltage battery, operational limits are defined in each case for one or more characteristic variables. Characteristic variables may be, for example, a voltage, a current, a temperature, a state of charge (SoC) or the like. The exceeding of respective operational limits is prevented during normal operation of the energy store by a control unit of the energy store in order to avoid in particular damage to the electrical energy store or premature aging phenomena.

#For the storage cells installed in an electrical energy store, a certain life is guaranteed by the manufacturer of the storage cells assuming a preset worst case scenario. An assumed load collective, an assumed temperature collective and a histogram of the operating states expected over the lifetime form the basis of the worst case scenario, which is also referred to as mission profile. In order to ensure this guaranteed life, the design of the electrical energy store needs to be based on a worst case scenario which corresponds to the worst possible (most severe) operating conditions and customer requests. This procedure means that from the production of the vehicle on, the maximum charging and discharging power over the lifetime is fixed. In addition, depending on a present state of health (SoH), a power enabled for a certain operating state is also limited.

#FIG. 1 is a schematic illustration of a device according to an embodiment of the invention for operating an electrical energy store.

#FIG. 2 is a graph visualizing the state of health of the electrical energy store shown in FIG. 1 as a function of time or a covered distance, wherein the principal procedure of an exemplary method according to the invention is illustrated using the graph.

#FIG. 3 is a development of the graph shown in FIG. 2 which illustrates the profile of the state of health over time or a covered distance and possible shifts, derived therefrom, in the operational limits of individual characteristic variables.

#FIG. 1 shows a device for operating an electrical energy store 10. The electrical energy store 10 represents an energy store for supplying power to components of an electrically operable vehicle, in particular a drive machine thereof. The electrical energy store 10 comprises a number of storage cell modules 100, 200, 300. The number of storage cell modules 100, 200, 300 can be selected in principle as desired. Each of the storage cell modules 100, 200, 300 in turn comprises a number of storage cells, wherein, by way of example, storage cells 101, . . . , 105 are only illustrated in the storage cell module 100.

#In a preferred configuration, each of the storage cells 101, . . . , 105 of a respective storage cell module 100, 200, 300 has a data memory 111, . . . , 115. The data memory 111, . . . , 115 has, in addition to the possibility of storing various data which will be described in more detail below, communication capabilities for data interchange with a control unit 20 of the electrical energy store 10 and optionally means for determining one or more characteristic variables of the assigned storage cells 101, . . . , 105. Characteristic variables of the energy store which are stored may be, for example, various histograms of past operating states of the respective voltages, charging and/or discharging currents, temperatures and states of charge (SoC), in each case in the form of maximum, minimum and average values. Furthermore, a so-called credential, i.e. a unique identification feature, of the assigned storage cell 101, . . . , 105 is stored in the data memory. The credential is protected by cryptographic methods and can be verified by a receiver of the credential. The data memories 111, . . . , 115 can, for this purpose, also have an arithmetic logic unit, which is suitable for implementing cryptographic operations. The data memories 111, . . . , 115 of respective storage cells 101, . . . , 105 represent data memory elements within the meaning of the invention, wherein the totality of all of the data memory elements forms a data memory of the electrical energy store 10.

#Although it is preferred if each of the storage cells 101, . . . , 105 of a respective storage cell module 100, 200, 300 has in each case such a data memory 111, . . . , 115, in one modification provision may be made for corresponding data memories 110, 210, 310 to be provided only for a respective storage cell module 100, 200, 300. If a data memory 110, 210, 310 is assigned to a respective storage cell module 100, 200, 300, these represent data memory elements. The totality of the data memory elements forms a data memory of the electrical energy store 10. In a further alternative configuration, such a data memory 11 may also be assigned only to the electrical energy store 10 as a whole.