Method, apparatus, computer program and computer readable storage medium for recovering battery capacity

Abstract

The invention relates to a method for restoring the capacity of a battery of a motor vehicle, in which the load of the battery is determined. And determining a battery capacity recovery mode according to the determined load. And according to the determined recovery mode, at least one discharge process of the battery is carried out at a predetermined discharge power so as to recover the capacity of the battery.

Description

Technical Field

[0001] The invention relates to a method for restoring the capacity of a motor vehicle battery. Furthermore, the invention relates to a device for restoring the capacity of a motor vehicle battery. Furthermore, the invention relates to a computer program for restoring the capacity of a motor vehicle battery. The invention also relates to a computer-readable storage medium on which the computer program is stored. Background Art

[0002] Modern vehicles are usually operated purely electrically and have batteries, in particular high-voltage batteries, for this purpose. These batteries are frequently charged and discharged and are subject to aging effects. Summary of the invention

[0003] The invention is based on the object of contributing to the restoration of battery capacity.

[0004] This object is achieved by the features of the independent claim. Advantageous embodiments are features of the dependent claims.

[0005] The invention is characterized by a method for restoring the capacity of a motor vehicle battery and a corresponding device.

[0006] In the method, a load of the battery is determined, a recovery mode of the battery capacity is determined according to the determined load, and at least one discharge process of the battery is performed at a predetermined discharge power according to the determined recovery mode to recover the battery capacity.

[0007] The battery is in particular a high-voltage battery of an electric vehicle or a hybrid vehicle, for example a lithium-ion battery, which has a silicon content, such as silicon oxide or silicon carbide, in particular on the anode side, for example a silicon content of between 5% and 20%.

[0008] In addition to charging, modern wallboxes also allow targeted discharge of the vehicle battery. It is precisely through targeted discharge that the battery capacity can be restored. This discharge is carried out by the described method so that the capacity of the battery, which has been lost, for example due to aging effects, is at least partially restored.

[0009] According to an optional configuration, the load is determined based on a comparison with data of other vehicles and / or a deviation of an operating voltage characteristic curve of the battery from an open circuit voltage characteristic curve of the battery and / or an aging characteristic value of the battery.

[0010] The load on the battery can be determined very precisely by comparison with data from other vehicles and / or deviations of the operating voltage characteristic curve of the battery from the open circuit voltage characteristic curve of the battery and / or aging characteristic values ​​of the battery. Aging characteristic values ​​include, for example, the age of the battery and / or the number of charging cycles that have been carried out.

[0011] According to another optional design solution, the recovery mode includes the number of discharge processes and / or a predetermined discharge depth of a corresponding discharge process.

[0012] Depending on the intensity of the load on the battery, it may make sense to perform a more intense recovery. For example, the recovery can be improved by the number of discharge operations (the more discharge operations, the better the recovery) and / or the depth of discharge (the more the battery is discharged, the better the recovery).

[0013] For example, the number includes repetitions of single-digit numbers, such as 1, 2, 3, or 4.

[0014] The depth of discharge can be given, for example, in stages, such as a first stage, in which the discharge is carried out with a constant current or a constant power until, for example, a battery state of charge (SoC) between 5% and 10% is reached, wherein the value 0% does not correspond to a completely discharged battery, but rather to a state in which the vehicle has stopped driving but the battery still has a predetermined residual capacity. In a second stage, the discharge is carried out, for example, with a constant current or with a constant power, until, for example, a battery state of charge between 0% and 5% is reached or until a predetermined minimum voltage of the battery is reached, which represents a state of charge below 0%. In a third stage, the discharge is carried out, for example, with a constant current, or first with a constant power and then with a constant voltage (CV), until, for example, a predetermined minimum voltage of the battery is reached.

[0015] The discharge takes place, for example, at a discharge power of between 0 and 4 kW, in particular between 2 and 3 kW, for example at 3 kW. Very good recovery is achieved precisely with such a low discharge power.

[0016] According to another optional configuration, cell balancing is performed before the at least one discharge process of the battery to compensate for charge differences between individual battery cells of the battery.

[0017] During cell balancing, for example, the individual cells of the battery are placed at the same voltage value, which can help to discharge the individual cells evenly during the discharge process.

[0018] According to another optional design solution, after the at least one discharge process of the battery, the battery is charged to a predetermined upper charge threshold at a predetermined charging power.

[0019] In the case of deep discharge, it is also advantageous to charge slowly again, in particular to charge in a current-controlled manner, for example to a charging power between 0 and 11 kW, in particular to 3 or 11 kW, to a state of charge of, for example, 10-30%, in particular to 30%. Subsequently, for example, it is also possible to charge to a state of charge of, for example, 80% at a charging power of more than 11 kW, as desired.

[0020] According to another optional configuration, the determined battery capacity recovery method is notified to the driver in order to confirm and / or plan the execution of the at least one discharging process.

[0021] Since the at least one discharging process and the optional charging process require a certain amount of time and the vehicle may not be able to be driven during this time (for example when discharging below a 0% state of charge), it is advantageous if the driver can plan the recovery so that, for example, the recovery can be carried out at a wall charger overnight and the vehicle is ready for use again the next morning.

[0022] According to another optional refinement, a recalibration of the charge state estimation is carried out as a function of the at least one discharging process.

[0023] By very deep discharging and subsequent charging, it is possible to determine very precisely how much remaining capacity the battery still has. This can then be used to better estimate the vehicle's state of charge.

[0024] Furthermore, the invention features a computer program for restoring the capacity of a motor vehicle battery, which includes instructions which, when the computer program is executed by a computer, cause the computer to perform a method for restoring the capacity of a motor vehicle battery.

[0025] Furthermore, the present invention is characterized by a computer-readable storage medium on which the computer program is stored.

[0026] A computer-readable storage medium includes, in particular, a medium which can be read by a data processing device and on which a program code is stored. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The embodiments of the present invention are described in more detail below with reference to the schematic drawings. The drawings are as follows:

[0028] Figure 1 a flow chart showing a procedure for restoring the capacity of a motor vehicle battery; and

[0029] Figure 2 A graph showing the remaining capacity of a battery as a function of operating time. DETAILED DESCRIPTION

[0030] Figure 1 A flow chart showing a procedure for restoring the capacity of a vehicle battery.

[0031] The device 50 is designed to process programs. For this purpose, the device 50 has, in particular, a computing unit, a program and data memory and, for example, one or more communication interfaces. The program and data memory and / or the computing unit and / or the communication interface can be configured in one structural unit and / or configured to be distributed on a plurality of structural units.

[0032] The device 50 may also be referred to as a device for restoring the capacity of a vehicle battery.

[0033] In particular, a program for this purpose is stored in the program and data memory of device 50 .

[0034] The program begins in step S1 , in which variables can be initialized if necessary.

[0035] In step S3 the load on the battery is determined.

[0036] The load is determined, for example, based on a comparison with data from other vehicles and / or a deviation of the operating voltage characteristic curve of the battery from the open-circuit voltage characteristic curve of the battery and / or an aging characteristic value of the battery.

[0037] The data of other vehicles include, for example, data about the remaining capacity of other comparable vehicles, ie, in particular, vehicles having the same battery.

[0038] The aging characteristic value includes, for example, the age of the battery and / or the number of charging cycles that have already been carried out.

[0039] In step S5, a battery capacity recovery method is determined according to the determined load.

[0040] The recovery method includes, for example, the number of discharge processes and / or a predetermined discharge depth of the corresponding discharge process.

[0041] For example, the number includes repetitions of single-digit numbers, such as 1, 2, 3, or 4.

[0042] The depth of discharge can be given, for example, in stages, such as a first stage, in which the discharge is carried out with a constant current or a constant power until, for example, a battery state of charge (SoC) between 5% and 10% is reached, wherein the value 0% does not correspond to a completely discharged battery, but rather to a state in which the vehicle has stopped driving but the battery still has a predetermined residual capacity. In a second stage, the discharge is carried out, for example, with a constant current or with a constant power, until, for example, a battery state of charge between 0% and 5% is reached or until a predetermined minimum voltage of the battery is reached, which represents a state of charge below 0%. In a third stage, the discharge is carried out, for example, with a constant current or with a constant power, or first with a constant power and then with a constant voltage (CV), until, for example, a predetermined minimum voltage of the battery is reached.

[0043] In step S7, at least one discharge process of the battery is performed at a predetermined discharge power according to the determined recovery mode to restore the battery capacity.

[0044] As described above, the discharging takes place differently depending on the phase, for example at a discharging power between 0 and 4 kW, in particular between 2 and 3 kW, for example at 3 kW.

[0045] If a plurality of discharging processes are carried out, the battery is recharged between the discharging processes to a predetermined state of charge of, for example, 10-30%.

[0046] After the last discharge process, the battery can still be charged higher, for example up to a charge state of 80% or 100%.

[0047] In the case of deep discharge, it is also advantageous to charge slowly again, in particular to charge in a current-controlled manner, for example to a state of charge of 10-30%, in particular to 30%, for example, at a charging power between 0 and 11 kW, in particular 3 or 11 kW. Subsequently, for example, charging can be performed as desired, for example to a state of charge of 80%, for example, at a charging power of more than 11 kW.

[0048] Before the discharge process is performed, for example, cell balancing is performed to compensate for charge differences between individual battery cells of the battery.

[0049] Before the discharge process is carried out, the driver is informed of the determined battery capacity recovery method, for example, in order to confirm and / or plan the implementation of the at least one discharge process. The driver can, for example, select when to carry out the recovery and / or how many discharge processes should be carried out and / or which stage of the discharge process should be carried out and / or to which charge state the vehicle should be recharged and / or when the vehicle should be recharged.

[0050] In step S9 the program ends and can be restarted if necessary.

[0051] It is through targeted discharge that the battery capacity can be restored. Figure 2 Shown in.

[0052] Figure 2 A diagram showing the residual capacity R of a battery as a function of the operating time t in years.

[0053] In the case of battery B1, no recovery is performed and the battery is operated under high load, in particular rapid charging is often performed. The battery is often operated in the marginal region of the state of charge (e.g. above 80% and below 20%) and / or the battery is subjected to high loads due to strong acceleration. It can be seen that such a battery reaches a residual capacity value of 80% relatively quickly, wherein 100% corresponds to the capacity in the new state.

[0054] Battery B3 operates optimally, ie is always in an optimal temperature range, optimal state of charge, optimal driving performance, parking performance, and charging performance.

[0055] It can be seen that such a battery reaches a residual capacity value of 80% very late, for example after eight years.

[0056] Battery B2 performed two restorations during the operating time (indicated by arrows), and otherwise operated like battery B1. It can be seen that battery B2 reached a residual capacity value of 80% significantly later than battery B1.

[0057] Reference numerals list

[0058] Steps S1-S9

[0059] 50 devices

[0060] B1, B2, B3 Batteries

Claims

1. A method for restoring the capacity of a motor vehicle battery, wherein: Determine the battery load, Determine the battery capacity recovery method based on the determined load, According to the determined recovery mode, at least one discharge process of the battery is performed at a predetermined discharge power to restore the battery capacity.

2. The method according to claim 1, wherein: The load is determined according to Comparison with other vehicles' data, and / or The deviation between the operating voltage characteristic curve of the battery and the open circuit voltage characteristic curve of the battery, and / or Aging characteristic value of the battery.

3. The method according to claim 1, wherein: The recovery method includes the number of discharge processes and / or a predetermined discharge depth of the corresponding discharge process.

4. The method according to claim 1 or 2, wherein: Cell balancing is performed before the at least one discharge process of the battery to compensate for charge differences between individual battery cells of the battery.

5. A method according to any one of the preceding claims, wherein: After the at least one discharge process of the battery, the battery is charged to a predetermined upper charge threshold at a predetermined charging power.

6. A method according to any one of the preceding claims, wherein: The determined battery capacity restoration method is communicated to the driver in order to confirm and / or plan the implementation of the at least one discharging process.

7. A method according to any one of the preceding claims, wherein: A recalibration of the state of charge estimation is performed as a function of the at least one discharging process.

8. A device for restoring the capacity of a motor vehicle battery, wherein: The device is designed to carry out the method according to any one of claims 1 to 7 .

9. Computer program for restoring the capacity of a motor vehicle battery, comprising instructions which, when the computer program is executed by a computer, cause the computer to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon the computer program according to claim 9.

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