Method and device for charging a battery for a forward motion mechanism

Abstract

The invention relates to a method and a device for charging a battery for a forward motion mechanism. The method comprises the following steps: obtaining a no-load voltage of the battery (30) based on a voltage ramp, the voltage ramp being generated by an adjustable DC / DC converter (40) electrically connected to the battery (30); obtaining the differential internal resistance of the battery (30) based on a predefined model for the differential internal resistance of the battery (30) and the no-load voltage; obtaining a target value for the output voltage of the DC / DC converter (40) based on the no-load voltage of the battery (30), a predefined charging current of the battery (30) and the differential internal resistance of the battery (30); and charging the battery (30) using the target value for the output voltage in the DC / DC converter (40).

Description

Technical Field

[0001] The present invention relates to a method and a device for charging a battery for a forward motion mechanism. Background Art

[0002] In an electrically driven forward motion mechanism, the low-voltage load of the forward motion mechanism is usually supplied by a DC / DC-converter, which converts the voltage of the high-voltage battery of the forward motion mechanism into a suitable low voltage. In addition, the low-voltage battery (e.g., a 12V or 24V battery) is usually also charged by the DC / DC-converter. In a low-voltage battery without a battery sensor, the output voltage of the DC / DC-converter is usually determined by the modeled battery temperature. In this case, the charging current is not regulated. Only by using a higher-priced corresponding battery sensor can the improvement of the charging strategy for the low-voltage battery be made possible. For the use of a battery sensor, which can be replaced (the battery sensor provides information such as current and / or voltage and / or temperature and / or state of charge (English is state of charge, abbreviated as SOC)), the current limit of the DC / DC-converter is sometimes used in the prior art to limit the charging current of the battery. However, when using such a method, it is necessary to know a load current that must be relatively constant in addition. For a known load current, the current limitation of the DC / DC converter is accordingly dimensioned in such a way that the desired load current is adapted to the low-voltage battery.

[0003] JP 2004-045235 describes a method for estimating the internal resistance of a battery on the basis of current values, voltage values ​​and temperature values ​​which are measured at three different points in time.

[0004] CN 108700636 describes a device for determining the degradation of a secondary battery, which includes a plurality of voltage sensors, a current measuring device, and a controller. Each voltage sensor is equipped with a sensor-specific wireless communication device, which is configured to transmit the respective measured values ​​to the controller. The controller calculates the internal resistance of the respective battery based on the measured values ​​and determines the degradation of the respective battery based on the internal resistance. Summary of the invention

[0005] The object of the present invention is to provide a method and a device for charging a battery for a forward motion mechanism, which method and device can be implemented in particular without the use of a battery sensor and without knowledge of the load current.

[0006] According to a first aspect of the invention, a method for charging a battery for a forward motion mechanism is proposed. The forward motion mechanism can be, for example, a road vehicle (e.g. a motorcycle, a car, a transport vehicle, a truck) or a rail vehicle or an aircraft / aircraft and / or a ship. The battery can be, in particular, a low-voltage starter battery or a low-voltage battery in the form of a lead-acid battery for the forward motion mechanism. Alternatively, the battery can also be a lithium-ion battery or a battery type different therefrom. The rated voltage of the battery can, for example, correspond to a voltage in the range of 6 V to 48 V, and preferably a voltage in the range of 12 V to 24 V, or a voltage different therefrom.

[0007] In a first step of the method according to the invention, the no-load voltage of the battery is detected on the basis of a voltage ramp which is generated by a controllable DC / DC converter which is electrically connected to the battery. For this purpose, the DC / DC converter is connected in information technology to an evaluation unit according to the invention which is a component of the DC / DC converter itself, a component of the battery or a component of another controller of the forward motion mechanism. The information technology connection of the evaluation unit to the DC / DC converter can be implemented, for example, on the basis of a bus system of the onboard electrical system of the forward motion mechanism (e.g. CAN (Controller Area Network), LIN (Local Interconnect Network), MOST (Media Oriented Information Transmission System), Flexray, etc.). In this way, the evaluation unit can be placed in a situation in which the DC / DC converter is actuated by means of corresponding control signals in order to predetermine target values ​​for the output current and / or output voltage of the DC / DC converter. The evaluation unit can be additionally configured to receive current values ​​for the output current and / or output voltage of the DC / DC converter from the DC / DC converter. The output voltage and output current should be understood here as values ​​of the battery (that is, of the low-voltage battery) that are made available by the DC / DC converter on the output side of the DC / DC converter. The electrical energy provided on the input side of the DC / DC converter can be provided in particular by a high-voltage battery of the forward motion mechanism, which can also be installed as an electrical energy storage for the drive train of the (electrically driven) forward motion mechanism. Therefore, the battery is configured on the DC / DC converter in order to be charged with the electrical energy of the high-voltage battery. In addition to or as an alternative to the high-voltage battery, a generator provided in the forward motion mechanism can also provide electrical energy for charging the battery. In such a case, in addition to or as an alternative to the high-voltage battery, the generator can be electrically connected to the input side of the DC / DC converter. The voltage ramp can preferably be carried out in a range that includes the rated voltage of the battery. The no-load voltage of the battery can be determined during the execution of the voltage ramp at a point in time at which no current is flowing between the output of the DC / DC converter and the battery. The voltage value received by the DC / DC converter via the evaluation unit at this point in time can be stored in a storage unit internally and / or externally connected to the evaluation unit for subsequent processing by the evaluation unit.

[0008] In the second step of the method according to the invention, the differential internal resistance of the battery is determined on the basis of a model for the differential internal resistance of the battery and the no-load voltage. The model for the differential internal resistance can, for example, also be stored in a memory unit connected to the evaluation unit. The model can in particular include a characteristic curve and / or a comprehensive characteristic curve, which represents the change in the voltage of the battery with respect to the change in the discharge current of the battery. The characteristic curve and / or the comprehensive characteristic curve can, for example, be determined during the development phase of the forward movement mechanism in which the battery is installed and / or of the battery, and can be stored in the respective memory units of the respective evaluation units during the mass production of the forward movement mechanism and / or of the battery. Based on the value for the no-load voltage determined in the first step of the method according to the invention, the value for the differential internal resistance of the battery corresponding to the no-load voltage can be determined by the evaluation unit on the basis of the model for the differential internal resistance.

[0009] In the third step of the method according to the invention, a target value for the output voltage of the DC / DC converter is determined on the basis of the no-load voltage of the battery, on the basis of a predefined charging current of the battery and on the basis of the differential internal resistance of the battery. The predefined charging current can be, for example, a value for a recommended charging current of the battery stored in the storage unit, the level of which can also be determined according to the rated capacity of the battery. The target value for the output voltage of the DC / DC converter can then be determined on the basis of the following formula:

[0010] U A =U 0 +I C *R diff

[0011] Among them, U A represents the target value for the output voltage of the DC / DC converter, U 0 Represents the obtained no-load voltage, I C represents the predefined charging current, and R diff represents the acquired differential internal resistance of the battery.

[0012] In a fourth step of the method according to the invention, the battery is charged using the target value for the output voltage in the DC / DC converter. In other words, the target value for the output voltage of the DC / DC converter determined in this way ensures that the battery can be charged with a predefined charging current.

[0013] It should be noted that the method according to the invention can preferably be used in a charging phase of the battery with a constant charging current, but is not limited to such a charging phase. In addition, the method can be repeated regularly or irregularly within such a charging process in order to ensure that the predefined charging current can be continuously maintained even under potentially changing boundary conditions (such as the temperature and / or capacity of the battery, etc.).

[0014] It should likewise be pointed out that a plurality of values ​​for a predefined charging current can also be stored in the memory unit, from which the respectively suitable predefined value for the predefined charging current can be used depending on the respective current boundary conditions.

[0015] The present invention also relates to other preferred improvements.

[0016] In an advantageous embodiment of the invention, the voltage ramp extends through a voltage range of 10 V to 14 V and preferably through a voltage range of 10.8 V to 13 V, without thereby limiting the method according to the invention to the aforementioned voltage range. Alternatively or in addition, the value of the voltage ramp and / or the average value of the voltage values ​​of the voltage ramp is determined based on a previously acquired value for the no-load voltage of the battery. The previously acquired value for the no-load voltage can be stored in a storage unit connected to the evaluation unit and, when necessary, read from the storage unit and used. By using the previously acquired value for the no-load voltage, the value of the voltage ramp can be reduced and, therefore, a shortening of the process for acquiring the no-load voltage of the battery is achieved.

[0017] In a further advantageous embodiment of the invention, the acquisition and use of the no-load voltage of the battery is again carried out in response to a change in the output current of the DC / DC converter. The change in the output current can be detected in the evaluation unit by means of the above-described information technology connection of the evaluation unit to the DC / DC converter. Preferably, for this purpose, a predefined threshold value for the change in the output current of the DC / DC converter can be stored in a memory unit connected to the evaluation unit, which threshold value can be corrected with the aid of the evaluation unit using the currently existing change in the output current. In the event that the currently existing change in the output current exceeds the predefined threshold value, the method according to the invention can be carried out again in order to ensure that a predefined charging current for the battery is maintained.

[0018] In a further advantageous embodiment of the invention, the model for the battery differential internal resistance is checked for plausibility or verified and / or adapted in a phase in which the no-load voltage is acquired and / or a predefined energy withdrawal from the battery is present. Such a predefined energy withdrawal can be present, for example, if information about currently active electrical consumers (e.g. a climate control of the forward motion mechanism) and information about the current and / or average energy consumption of these electrical consumers is present in the evaluation unit. Such information can be provided to the evaluation unit, for example, by the respective electrical consumers via the onboard electrical system of the forward motion mechanism. Alternatively, predefined average energy consumption values ​​for the respective electrical consumers of the forward motion mechanism can also be stored in the memory unit of the evaluation unit, so that only the respective activation state of each electrical consumer needs to be transmitted to the evaluation unit via the onboard electrical system.

[0019] In another advantageous technical solution of the present invention, the model for the battery differential internal resistance additionally takes into account the current temperature of the battery, wherein the temperature is acquired on the basis of temperature measurements and / or on the basis of a temperature model for the battery. In the case of temperature measurements, for example, a temperature sensor of the battery and / or a temperature sensor in the surroundings of the battery can be connected to the evaluation unit in an information technology manner, so that the temperature information can be detected and used in the evaluation unit. By acquiring the temperature, the influence of the temperature on the battery differential internal resistance can be taken into account accordingly, thereby making it possible to more accurately determine the current target value for the output voltage of the DC / DC converter. This in turn ensures that the predefined charging current is followed more accurately.

[0020] In a further advantageous embodiment of the invention, the model for the differential internal resistance of the battery additionally takes into account the aging of the battery. Since the internal resistance of the battery can increase, for example, as a function of the number of charging cycles that have been carried out and / or as a function of the duration of use of the battery to date, in this way it is possible to achieve a more precise determination of the target value for the output voltage of the DC / DC converter and a more precise adherence to the predefined charging current.

[0021] In another advantageous technical solution of the present invention, the model for the differential internal resistance is verified and / or adapted in an external server based on information from a plurality of forward motion mechanisms. To this end, the forward motion mechanisms participating in the method according to the present invention can have respective wireless communication devices, which are set up to establish a wireless communication connection (e.g., a mobile radio connection and / or a WLAN (wireless local area network) connection, etc.) with the external server. In this way, the forward motion mechanisms can transmit respective information about the acquired battery state and / or charge state to the server, so that the server can mutually correct this information. On the basis of this information, the model for the differential internal resistance of the battery can be adapted by the server, if necessary, to the changing values ​​in the batch application of the forward motion mechanism, etc., so as to make it possible to determine the differential internal resistance more accurately. For this purpose, the server can transmit the adapted model to the plurality of forward motion mechanisms by means of the wireless communication device, so that the adapted model can be used in the plurality of forward motion mechanisms later instead of the previously used model.

[0022] According to a second aspect of the invention, a device for charging a battery for a forward motion mechanism is proposed. The device comprises an evaluation unit having a data input and a data output. The evaluation unit can be constructed, for example, as an ASIC (application-specific integrated circuit), an FPGA (field programmable gate array), a processor, a digital signal processor, a microcontroller, etc., and is connected to an internal and / or external storage unit in terms of information technology. The evaluation unit is connected to the data input and is set up to detect the no-load voltage of the battery on the basis of a voltage ramp, which is generated by an adjustable DC / DC converter electrically connected to the battery. In addition, the evaluation unit is set up to detect the differential internal resistance of the battery on the basis of a predefined model for the differential internal resistance and on the basis of the detected no-load voltage. The evaluation unit is additionally configured to determine a target value for the output voltage of the DC / DC converter based on the no-load voltage of the battery, on a predefined charging current of the battery and on a differential internal resistance of the battery, and to charge the battery using the target value for the output voltage in the DC / DC converter in connection with the data output.

[0023] Furthermore, the device according to the invention is set up to carry out the method according to the invention according to the above description. The method can preferably be implemented in the form of a computer program, which can be executed by the evaluation unit. The technical features, combinations of technical features and the advantages resulting therefrom correspond clearly to the technical features, combinations of technical features and the advantages resulting therefrom which are carried out in connection with the first-mentioned inventive aspect: to avoid repetitions, reference is made to the above-mentioned exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings. Here, the drawings show: Figure 1 a flow chart illustrating the steps of an embodiment of a method according to the present invention; and

[0025] Figure 2 Schematic overview of the device according to the invention in conjunction with a forward motion mechanism. DETAILED DESCRIPTION

[0026] Figure 1A flowchart illustrating the steps of an exemplary embodiment of a method according to the invention for charging a battery for a forward motion mechanism is shown. In step 100 of the method according to the invention, the no-load voltage of a 12V starter battery (here a lead-acid battery) is detected on the basis of a voltage ramp, which is generated by an adjustable DC / DC converter electrically connected to the starter battery. The DC / DC converter is connected on the input side to a high-voltage battery of the forward motion mechanism, from which the DC / DC converter can receive electrical energy for charging the starter battery. The no-load voltage is detected by means of an evaluation unit according to the invention, which is a microcontroller here and is connected in terms of information technology to the control and read interface of the DC / DC converter. Due to the execution of the voltage ramp initiated by the evaluation unit, which runs through the voltage range of 10.8 V to 13 V, the evaluation unit determines at a voltage value of 12 V of the voltage ramp that no current is flowing between the starter battery and the output side of the DC / DC converter. For this reason, a voltage value of 12 V is determined according to the method according to the invention as the no-load voltage of the starter battery to be determined. In step 200 of the method according to the invention, the differential internal resistance of the starter battery is determined on the basis of a predefined model for the differential internal resistance of the starter battery and the determined no-load voltage. The model is stored in a memory unit connected to the evaluation unit. In step 300 of the method according to the invention, a target value for the DC / DC converter output voltage is determined by means of the evaluation unit on the basis of the no-load voltage of the starter battery, on the basis of the predefined charging current of the battery and on the basis of the determined differential internal resistance of the starter battery. The starter battery is charged using a target value for the output voltage in the DC / DC converter in step 400. For this purpose, the target value for the output voltage of the DC / DC converter, which is determined by the evaluation unit, is transmitted from the evaluation unit to the DC / DC converter and is used therefor to adapt the output voltage.

[0027] Figure 2A schematic overview of a device according to the invention associated with a forward motion mechanism 90 is shown. The device comprises an evaluation unit 10 according to the invention, which has a data input 12 and a data output 14 and which is here an ASIC (application-specific integrated circuit). The evaluation unit 10 is connected in terms of information technology to a storage unit 20 externally connected to the evaluation unit 10, in which data received and / or processed by the evaluation unit 10 can be stored for subsequent processing by the evaluation unit 10. The evaluation unit 10 is connected in terms of information technology to a DC / DC converter 40 of the forward motion mechanism 90 by means of the data input 12 and by means of the data output 14. The input side of the DC / DC converter 40 is electrically connected to a high-voltage battery 50 of the forward motion mechanism 90, while the output side of the DC / DC converter is connected to a 12V battery 30 of the forward motion mechanism 90, which is here a starter battery. The DC / DC converter 40 is configured in conjunction with the control by the evaluation unit 10 and the high-voltage battery 50 to charge the battery 30 with a predefined charging current. The evaluation unit 10 is additionally connected to a wireless communication device 80 of the forward motion mechanism 90, which is a mobile radio device in this case, by means of the data input 12 and the data output 14. The evaluation unit 10 is configured to transmit information about the charging process and state of the battery 30 via a wireless communication connection 85 to an external server 70 located next to the forward motion mechanism 90, or to receive an updated model for determining the differential internal resistance of the battery 30 from the external server 70. The device according to the invention is configured on the basis of the above-described configuration to carry out the method according to the invention described above for charging the battery 30.

Claims

1. A method for charging a battery (30) for a forward motion mechanism (90), comprising: The no-load voltage of the battery (30) is detected (100) on the basis of a voltage ramp, which is generated by an adjustable DC / DC converter (40) which is electrically connected to the battery (30); Obtaining (200) the differential internal resistance of the battery (30) based on a predefined model for the differential internal resistance of the battery (30) and the no-load voltage; A target value for the output voltage of the DC / DC converter (40) is obtained (300) based on: a no-load voltage of the battery (30), a predefined charging current of the battery (30), and a differential internal resistance of the battery (30); and The battery (30) is charged (400) using a target value for an output voltage in the DC / DC converter (40).

2. The method according to claim 1, wherein: The battery (30) is a low-voltage battery which is charged via the DC / DC converter (40) with the aid of electrical energy from a high-voltage battery (50) of the forward motion mechanism (90).

3. The method according to claim 1 or 2, wherein: The voltage ramp runs through a voltage range of 10V to 14V; and / or The value of the voltage ramp and / or the average value of the voltage values ​​of the voltage ramp is determined based on previously determined values ​​for the no-load voltage of the battery (30).

4. The method according to claim 1 or 2, wherein: The no-load voltage of the battery (30) is reached when no current is flowing between the DC / DC converter (40) and the battery (30).

5. The method according to claim 1 or 2, wherein: In response to a change in the output current of the DC / DC converter (40), the no-load voltage of the battery (30) is again captured and used.

6. The method according to claim 1 or 2, wherein: A model for the differential internal resistance of the battery (30) is verified and / or adapted in a phase in which The no-load voltage is obtained, and / or There is a predefined energy extraction from the battery (30).

7. The method according to claim 1 or 2, wherein: The model for the differential internal resistance of the battery (30) additionally takes into account the current temperature of the battery (30), wherein the temperature is determined on the basis of: Temperature measurement, and / or A temperature model for the battery (30).

8. The method according to claim 1 or 2, wherein: The model for the differential internal resistance of the battery (30) additionally takes into account the aging behavior of the battery (30).

9. The method according to claim 1 or 2, wherein: The model for the differential internal resistance is verified and / or adapted in an external server (70) based on information from a plurality of progressive motion mechanisms.

10. The method according to claim 1 or 2, wherein: The differential internal resistance of the battery is detected during a charging phase with a constant charging current.

11. The method according to claim 3, wherein: The voltage ramp runs through a voltage range of 10.8V to 13V.

12. A device for charging a battery (30) for a forward motion mechanism (90), comprising: Evaluation unit (10), a data input terminal (12), and Data output terminal (14), Therein, the evaluation unit (10) is set up, so as to obtain the no-load voltage of the battery (30) by connecting to the data input terminal (12) on the basis of a voltage ramp, which is generated by an adjustable DC / DC converter (40) electrically connected to the battery (30); Obtaining the differential internal resistance of the battery (30) based on a predefined model for the differential internal resistance and the no-load voltage; The target value for the output voltage of the DC / DC converter (40) is obtained based on: the no-load voltage of the battery (30); the predefined charging current of the battery (30) and the differential internal resistance of the battery (30); as well as The battery (30) is charged in connection with the data output (14) using a target value for the output voltage in the DC / DC converter (40).

13. The device according to claim 12, wherein: The device is set up to carry out the method according to any one of claims 1 to 11.

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