Method for assessing an electrical connection of an electrical energy storage device with an on-board electrical system, as well as an electronic battery assessment system and vehicle

Abstract

Method for assessing an electrical connection (9) of an electrical energy storage device (7) with an on-board network (5) of an at least partially electrically powered vehicle (1), wherein - the on-board electrical system (5) is supplied with electrical energy by the electrical energy storage device (7), and - with a voltage converter (8) of the vehicle electrical system (5), which is connected to the electrical energy storage device (7), at least one component (6) of the vehicle electrical system (5) is supplied with an output voltage (UA) of the voltage converter (8), comprising: - Changing a setpoint voltage (UV) of the voltage converter (8), with which the output voltage (UA) can be set, within a specified time interval (T), thereby generating a battery voltage (U Batt ) and a battery current (I Batt ) of the electrical energy storage device (7) can be influenced, - Detecting the battery voltage (U) Batt) of the electrical energy storage device (7) within the time interval (T) with a detection unit (14), - Recording the battery current (I Batt ) of the electrical energy storage device (7) within the time interval (T) with a detection unit (15), characterized by - Comparing a time course (16) of the battery voltage (U Batt ) and a time course (17) of the battery current (I Batt ) with an evaluation unit (11) - Assessing the electrical connection (9) of the electrical energy storage device (7) with the vehicle electrical system (5) depending on the compared time profiles (16, 17) of the battery voltage (U) Batt ) and the battery current (I Batt ) by the evaluation unit (11), wherein - when comparing the time profiles (16, 17) of the battery voltage (U Batt ) and the battery current (I Batt) is checked to see if these two time series (16, 17) are in phase.

Description

[0001] The invention relates to a method for evaluating an electrical connection of an electrical energy storage device with an on-board power supply of an at least partially electrically operated vehicle, wherein the on-board power supply with the electrical energy storage device is supplied with electrical energy and at least one component of the on-board power supply is supplied with an output voltage of the voltage converter by means of a voltage converter of the on-board power supply which is connected to the electrical energy storage device.

[0002] Furthermore, the invention relates to an electronic battery assessment system comprising an evaluation unit and at least one acquisition unit. The invention also relates to a vehicle equipped with an electronic battery assessment system.

[0003] Electrically powered vehicles, such as electric vehicles or hybrid vehicles, have a complex electrical system. This system can be divided into sub-systems, each with its own specific voltage level. For such electrically powered vehicles, it is crucial to check whether the battery is still connected to the electrical system and therefore available. Various state-of-the-art diagnostic methods can be used to determine whether the battery is still live and connected to the vehicle's electrical system while it is active. This allows for the determination of whether the battery is "disconnected," meaning it is no longer connected.

[0004] One problem is that the vehicle's battery is connected in parallel to another voltage source, meaning that a simple voltage measurement or a reaction to a voltage drop is insufficient for detection. Another method used today is to actively determine the battery's internal resistance using various techniques.

[0005] For example, DE 10 2016 216 845 A1 discloses a device and a method for detecting a missing electrical connection between an energy storage device and a power supply system. In this process, a current flowing in the power supply system or energy storage device is detected using current sensing, and a variation in the current is determined and compared with a threshold value.

[0006] Furthermore, DE 102 19 824 A1 discloses a method and a device for detecting vehicle operation without a battery. In this process, both the generator voltage and the battery voltage can be determined or measured, and both voltages or the voltage ripples derived from both voltages can be related to or compared with each other, and battery-less vehicle operation can be detected.

[0007] CN 1 05 556 320 A discloses a method for detecting a battery that is no longer connected to a vehicle's electrical system. Furthermore, CN 1 05 158 573 B discloses a circuit for determining the internal resistance of a battery.

[0008] Furthermore, DE 10 2014 004 791 B3 discloses a method for verifying a connection between a battery supplying a low-voltage network and a DC-DC converter. For this purpose, the DC-DC converter can be controlled by an energy management control unit to modulate the output voltage of the DC-DC converter, so that a current is impressed into the battery, and the current and voltage in the battery can be measured using a current sensor and a voltage sensor.

[0009] Simple voltage measurements have the disadvantage that an additional voltage source, especially a generator or DC / DC converter, is active alongside the battery, meaning the system is still running. Therefore, a simple voltage measurement is not feasible. Determining the battery's internal resistance, particularly its ohmic component, presents a problem: interruptions in the current path, for example, can introduce AD ​​converter noise during current measurement. This noise is statistically distributed, leading to randomly occurring values ​​that are either good or bad. In such cases, one would expect the values ​​to approach infinity. Similarly, the vehicle's electrical system may provide only a weak excitation due to its current state, preventing any meaningful data analysis.

[0010] One object of the present invention is to make it easier and less costly to check an electrical connection between an electrical energy storage device and the vehicle's electrical system.

[0011] This problem is solved by a method, an electronic battery assessment system, and a vehicle according to the independent claims. Meaningful further developments arise from the dependent claims.

[0012] One aspect of the invention relates to a method for assessing an electrical connection of an electrical energy storage device with an on-board network of an at least partially electrically powered vehicle, wherein - the vehicle electrical system is supplied with electrical energy via the electrical energy storage device, and - comprising a voltage converter of the vehicle electrical system, which is connected to the electrical energy storage device, and at least one component of the vehicle electrical system is supplied with an output voltage of the voltage converter: - Changing a setpoint voltage of the voltage converter, with which the output voltage can be specified, within a specified time interval, thereby influencing the battery voltage and battery current of the electrical energy storage device. - Detecting the battery voltage of the electrical energy storage device within the time interval using a detection unit, - Recording the battery current of the electrical energy storage device within the time interval using a recording unit, - Comparing the time course of the battery voltage and the time course of the battery current with an evaluation unit, - Assessing the electrical connection of the electrical energy storage device with the vehicle electrical system based on the compared time profiles of the battery voltage and battery current by the evaluation unit.

[0013] The proposed method allows for the simple detection and verification of whether a vehicle battery is electrically connected to the vehicle's electrical system. In other words, it can detect whether the vehicle's current battery is still connected to the electrical system and available. This enables verification of the vehicle battery's current electrical system connectivity. In particular, this can be done more easily, cost-effectively, and with less effort using the proposed method.

[0014] By assessing the electrical connection of the electrical energy storage device to the vehicle's electrical system based on the compared time profiles, it can be determined whether the electrical energy storage device is currently electrically connected or wired to the vehicle's electrical system. This assessment can also be used to verify and monitor the condition and quality of the electrical connection between the electrical energy storage device and the vehicle's electrical system.

[0015] The electrical energy storage device is, for example, a vehicle battery or accumulator. In particular, the electrical energy storage device can be a high-voltage battery. The vehicle electrical system can be, for example, the entire electrical system of the vehicle or a section of it. In particular, the vehicle can be its energy supply system. With the help of the electrical energy storage device and the vehicle electrical system, an electric drive machine, especially an electric motor, can be operated, enabling the vehicle to move.

[0016] For example, the vehicle electrical system can be a low-voltage system, which can be used to operate or supply electrical devices. The components of the electrical system can also be low-voltage components.

[0017] For example, these components can operate at a voltage between 11 and 14 volts, particularly 12 volts. The vehicle's electrical system, for instance, could be a 12-volt or 24-volt system. In this case, it could be a sub-system of the vehicle's high-voltage electrical system. The components of the electrical system could be safety-relevant systems, such as steering or braking systems. Since such safety-critical systems must be protected by a redundant power supply, a functioning electrical connection between the electrical system and the electrical energy storage device is essential.

[0018] In order to supply the component(s) with a suitable voltage, in particular a low-voltage voltage, the voltage of the electrical energy storage device can be converted or transformed using a voltage converter.

[0019] For example, the voltage converter can be a DC-DC converter, a DC-DC converter, or a DC generator. The voltage of the electrical energy storage device can be supplied to the voltage converter as its input voltage, allowing the converter to transform this input voltage into a corresponding output voltage. The output voltage can then be supplied to or transmitted to at least one component of the vehicle's electrical system, or to other systems or units within the electrical system.

[0020] For example, the input voltage of the voltage converter can be varied or changed using a control unit. The input voltage allows the voltage converter to be parameterized or set so that a desired output voltage can be achieved. Specifically, the input voltage of the voltage converter is converted into the output voltage depending on the specified input voltage. In other words, the input voltage determines the voltage level at the output of the voltage converter. The input voltage is changed alternately over time. It is altered within a predetermined time interval or duration. This can be done automatically by the control unit.Changing the input voltage, and thus the voltage conversion of the voltage converter, affects the electrical energy storage device if it is connected to the voltage converter. Therefore, the battery voltage and / or current of the electrical energy storage device can be influenced, and in particular impaired, by changing the input voltage. In other words, changing the input voltage can actively excite the voltage converter and subject it to a quasi-interference frequency.

[0021] For example, the change in the set voltage can change periodically every 100 milliseconds.

[0022] For example, battery voltage can be detected or measured using a voltage measurement. A voltmeter can be used as the measuring device for this purpose. Battery current can be detected or measured using a current measurement. An ammeter can be used as the measuring device for this purpose. In particular, battery voltage and battery current can be detected using one and the same measuring device. In this case, it can be a measuring device that can measure both voltages and currents. Alternatively, there can be a first measuring device for detecting the battery voltage and a second measuring device for detecting the battery current.

[0023] Specifically, within the time interval, i.e., as long as the setpoint voltage is changed, the respective time profiles of the battery voltage and battery current are recorded. These two time profiles of the battery voltage and battery current are compared and analyzed by the evaluation unit, in particular an electronic evaluation unit or processing unit. The time profiles are compared and checked to determine whether changes caused by the altered setpoint of the voltage converter can be detected. Thus, it can be determined from the time profiles of the battery voltage and battery current whether the setpoint voltage of the voltage converter has changed. In other words, the changed setpoint voltage affects the time profiles of the battery voltage and battery current.This is because the voltage converter can be considered a load, or electrical load, of the electrical energy storage device. Thus, a change in the voltage converter's setpoint voltage can induce a change in the load on the electrical energy storage device. This can then be taken into account when assessing the electrical connection between the electrical energy storage device and the vehicle's electrical system. The assessment focuses particularly on whether the changed setpoint voltage, or the time-varying of the voltage converter's setpoint voltage, is discernible or detectable in the time-dependent curves of the battery voltage and current. If this is the case, it can be concluded that the electrical energy storage device is electrically connected to the vehicle's electrical system. Otherwise, a faulty or damaged electrical connection is present.

[0024] For example, the result of the assessment of the electrical connection can be made available to a safety system of the vehicle or to another device of the vehicle.

[0025] For example, the voltage converter's setpoint voltage can be repeatedly changed until the vehicle's battery or electrical energy storage device is recognized as present. For instance, the voltage change can be repeated ten times, particularly twenty times, or in a range between ten and twenty repetitions.

[0026] The proposed method eliminates the need for complex frequency generator controls to define a frequency setpoint, which can generate interference. This interference can be prevented by the proposed method.

[0027] The proposed method allows an interference frequency to be applied to the voltage converter, particularly at a predetermined time interval. This can generate a detuning of the voltage converter sufficient to produce an excitation strong enough to determine the internal resistance.

[0028] In one embodiment of the invention, the setpoint voltage is changed in such a way that a voltage value of the setpoint voltage is increased or decreased by a predetermined voltage value within the time interval in which a voltage value of the setpoint voltage is increased or decreased periodically by the predetermined voltage value. In particular, the change of the setpoint voltage is carried out repeatedly or alternately.

[0029] For example, the setpoint voltage can be increased for 100 milliseconds and then decreased again for 100 milliseconds. The increase or decrease of the voltage network always occurs from the initial value of the setpoint voltage.

[0030] For example, the setpoint voltage is increased by 50 millivolts for 100 milliseconds, then decreased by 50 millivolts for another 100 milliseconds. This creates a periodic, alternating increase or decrease of the setpoint voltage, specifically its base value. This allows for periodic changes in the setpoint voltage. This can be achieved by initiating the change in the setpoint voltage of the voltage transformer.

[0031] In particular, the setpoint voltage of the voltage converter can be varied by a typical time interval of, for example, 100 milliseconds. This is done by alternating between the current setpoint voltage value. For example, the setpoint voltage could be 13.8 volts, so that 13.85 volts or 13.75 volts are set alternately as the setpoint voltage. This occurs in a periodic process. The setpoint voltage value is such that the properties of the vehicle electrical system and / or at least one component remain unchanged, but an influence on the battery voltage and current is detectable. In particular, the setpoint voltage value should be defined or specified in such a way that it has at least no, and especially no significant, influence on the properties of the vehicle electrical system and / or other systems of the vehicle.

[0032] Changing the input voltage of the voltage converter does not cause the electrical energy storage device to experience a massive current draw, but only a brief peak or current surge. This can be detected in the time-dependent current profiles.

[0033] The system is designed to compare the time-dependent curves of the battery voltage and current to verify that these two curves are in phase. This allows for the assessment of the electrical connection between the energy storage device and the vehicle's electrical system by checking the phases of the battery voltage and current. This provides a simple and efficient method for verifying that the energy storage device is still connected to the vehicle's electrical system. Specifically, the verification is performed by checking whether the battery current and voltage are in phase. If the energy storage device is still connected to the vehicle's electrical system, the battery current and voltage will be directly proportional when the voltage converter is energized.If the electrical energy storage device is no longer connected to the vehicle's electrical system, the battery voltage and battery current are no longer in phase and, in particular, these two are no longer proportional to each other.

[0034] In other words, if the measured battery voltage and the measured battery current are still in phase after the voltage converter is excited by the changed target voltage, it can be assumed that the electrical energy storage device is still present or connected in the circuit of the vehicle electrical system.

[0035] If the electrical energy storage device is not connected to the vehicle's electrical system, or especially if the connection is inadequate, the current and voltage will not be in phase. In such a case, the detection units would register statistical noise or stochastic fluctuations as battery current.

[0036] In particular, the proposed method can be used to verify whether the battery current and battery voltage signals are in phase.

[0037] In one embodiment, it is provided that changing the setpoint voltage triggers the determination of the internal resistance of the electrical energy storage device. Specifically, the change in the voltage converter's setpoint voltage is such that a corresponding excitation is sufficient to determine the internal resistance of the electrical energy storage device. Therefore, the setpoint voltage should be set to allow for an accurate and, in particular, efficient determination of the internal resistance. Specifically, determining the internal resistance of the electrical energy storage device is feasible when the battery current and voltage are in phase. Thus, the battery voltage and current are proportional to each other.

[0038] When an electrical energy storage device is connected, its internal resistance remains constant because the battery current and voltage are proportional to each other. In other words, if the battery current and voltage are in phase, an ohmic resistance, or rather an ohmic component of the internal resistance of the electrical energy storage device, can be determined. This indicates that the electrical energy storage device is properly connected to the vehicle's electrical system. If the connection is faulty or disconnected, the battery voltage and current are not proportional, and no ohmic resistance can be determined. This can be taken into account when assessing the electrical connection.

[0039] In particular, the proposed method allows for a change in the current of the electrical energy storage device by changing the voltage setting, thus enabling a concrete evaluation of the ohmic component of the internal resistance of the electrical energy storage device.

[0040] The performance of an electrical energy storage device can be assessed by determining its internal resistance.

[0041] The variable input voltage allows the battery current to react in a way that excites the voltage converter. This provides the necessary excitation to determine the internal resistance.

[0042] In a further embodiment of the invention, the internal resistance is determined based on an average voltage and an average current over the time course of the battery voltage. Thus, the internal resistance is determined by dividing the average current by the average voltage. The average voltage and the average current can be determined, for example, using the evaluation unit. The average voltage and the average current can each be an RMS value of the battery voltage and an RMS value of the battery current, respectively.This allows for a more efficient, and in particular more accurate, determination of the internal resistance. The determined internal resistance can then be considered or used as a further indicator when assessing the electrical connection of the electrical energy storage device to the vehicle's electrical system.

[0043] In one embodiment, the setpoint voltage is changed depending on a predetermined switching frequency. For example, the predetermined switching frequency corresponds to a predetermined time interval. Specifically, the predetermined switching frequency is used by the control unit to alternately change the setpoint voltage. Thus, the voltage converter can be excited accordingly using the predetermined switching frequency, and the setpoint voltage can be varied. This allows the voltage converter to be controlled or excited in such a way that the time-dependent profiles of the battery voltage and battery current can be recorded and used to assess the connectivity of the electrical energy storage device.

[0044] For example, the switching frequency can be used to periodically change the setpoint voltage. The setpoint voltage can, for instance, be described as the control and / or regulated variable of the voltage converter.

[0045] In another embodiment, it is provided that, for the comparison of the time-dependent waveforms of the battery voltage and battery current, the waveforms are filtered using a digital filter depending on the changing target voltage. For example, a bandpass filter can be used as the digital filter. With the help of the digital filter, a corresponding frequency range can be limited or specified within which the battery current and battery voltage are analyzed. By filtering the predefined time interval, interference can be eliminated and a better assessment of the electrical connection can be carried out.

[0046] In one embodiment of the invention, it is further provided that a step response, as a time-dependent profile of the battery voltage and battery current, is determined immediately after changing the setpoint voltage. For example, the respective step responses can be acquired using the sensing unit(s). Alternatively, the step responses can be determined using the evaluation unit or an electronic circuit. In other words, a current response and a voltage response can be generated by changing or exciting the voltage converter with the setpoint voltage. For example, the step response of the battery current can be a current response or current pulse. The step response with respect to the battery voltage can be a voltage excitation.When measuring the battery voltage and current, the respective current responses can be recorded based on their time-dependent curves. If the two step responses have the same period, the electrical energy storage device can be assumed to have an intact connection.

[0047] A further aspect of the invention relates to an electronic battery evaluation system comprising an evaluation unit and at least one detection unit, wherein the electronic, in particular electrical, battery evaluation system is configured to carry out a method according to the previous aspect or an advantageous embodiment thereof. In particular, the method described above or an advantageous embodiment thereof can be carried out with the battery evaluation system just described.

[0048] The battery assessment system can be, for example, an electronic measuring device or an electrical circuit. For instance, the battery assessment system can be located in the vehicle's electrical system of a vehicle that is at least partially electric. Specifically, the battery assessment system can be used to assess, evaluate, or determine whether a vehicle battery in a vehicle that is at least partially electric is currently connected to the vehicle's electrical system.

[0049] Another aspect of the invention relates to a vehicle with a battery assessment system according to the previous aspect or an advantageous further development. For example, the vehicle may be at least partially electrically powered, such as an electric vehicle or a hybrid vehicle. For example, the vehicle may have an electrical system. In particular, the battery assessment system may be designed as an independent unit, device, or system, or it may be part of the electrical system.

[0050] A battery, in particular an electrical energy storage device, according to the invention comprises at least one and, in particular, several electrically interconnected battery cells, wherein such a battery cell preferably provides a voltage in the range of 3.5 to 4.0 volts. Such a battery cell can, for example, be designed as a prismatic cell, a pouch cell, or a cylindrical cell. The battery is preferably designed as a so-called high-voltage battery, which is configured to provide an electrical voltage in the range of more than 60 volts, in particular in the range of several hundred volts. Such a high-voltage battery can be arranged in a motor vehicle, where it can supply an electrical consumer, in particular a drive motor, with electrical energy.

[0051] In particular, advantageous embodiments of one aspect can be regarded as advantageous embodiments of the other aspects and vice versa.

[0052] Advantageous embodiments of the method can be considered advantageous embodiments of the electronic battery assessment system and the vehicle. The reverse is also true.

[0053] The invention also includes further developments of the electronic battery assessment system and the vehicle according to the invention, which have features already described in connection with the further developments of the method according to the invention. For this reason, the corresponding further developments of the electronic battery assessment system and the vehicle according to the invention are not described again here.

[0054] The invention also includes combinations of the features of the described embodiments.

[0055] The following describes exemplary embodiments of the invention. This is illustrated by: Fig. 1 a schematic representation of a vehicle with at least one electrical energy storage device and at least one electrical on-board network and an electronic battery assessment system; Fig. 2 an exemplary time course of a battery current of the electrical energy storage device Fig. 1; Fig. 3 an exemplary time course of a battery voltage of the electrical energy storage device Fig. 1; and Fig. 4 exemplary time profiles of electrical power, battery voltage and battery current of the electrical energy storage device from Fig. 1.

[0056] The embodiments described below are preferred embodiments of the invention. In these embodiments, the described components each represent individual features of the invention that can be considered independently of one another. Each of these features further develops the invention independently and can therefore be considered part of the invention individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by other features of the invention already described.

[0057] In the figures, functionally identical elements are each provided with the same reference symbols.

[0058] The Fig. Figure 1 shows a schematic view of a vehicle 1 that is at least partially electrically powered. The vehicle 1 could be, for example, an electric vehicle or a hybrid vehicle.

[0059] For example, vehicle 1 has an electric drive unit 2 with which vehicle 1 can be moved. In order for vehicle 1 to be driven by the electric drive unit 2, or by an electric motor, to carry out a journey, vehicle 1 can have at least an electrical system 3 and, for example, a high-voltage battery 4. The high-voltage battery 4, for example, has a voltage in the high-voltage range. The electrical system 3 can, for example, be a high-voltage electrical system. This electrical system 3 and the high-voltage battery 4 can, for example, be used to supply power to the electric drive unit 2.

[0060] Since vehicle 1 can be, for example, a highly automated vehicle, it can have numerous safety systems and / or driver assistance systems. These can be used, for example, for steering and braking. Because these systems require a redundant power supply, vehicle 1 can, for example, have an additional electrical system 5. Electrical system 5 can be a low-voltage system, for example, compared to electrical system 3. Electrical systems 3 and 5 can also be one and the same system. For example, electrical system 3 can be a first sub-system and electrical system 5 a second sub-system of a higher-level electrical system of vehicle 1. Electrical system 5 can, for example, be used to operate at least one component 6 and, in particular, to supply it with electrical energy.The vehicle electrical system 5 can include various electrical energy storage devices 7 in addition to the high-voltage battery 4. For example, the electrical energy storage device 7 can be a vehicle battery or an accumulator. In particular, unlike a high-voltage battery 4, the electrical energy storage device 7 can be a low-voltage battery. For example, the electrical energy storage device 7 can be indirectly connected to the high-voltage battery 4. In particular, the electrical energy storage device 7 and the vehicle electrical system 5 can have a voltage of 12 volts, 24 volts, 36 volts, or 48 volts.

[0061] In order to efficiently supply at least one component 6, which could be, for example, a safety system, a longitudinal system, or a braking system, with a suitable voltage, the vehicle electrical system 5 has at least one voltage converter 8. The voltage converter 8 could, for example, be a DC-DC converter. With the help of the voltage converter 8, a battery voltage U, for example, can be converted. batt The electrical energy storage device 7 is converted into an output voltage UA. For this purpose, the battery voltage U can be supplied to the voltage converter 8 as the input voltage UE. battThe electrical energy storage device 7 is supplied with or provided with this input voltage UE. This input voltage UE applied to the voltage converter 8 can then be converted or transformed into the output voltage UA. For example, the output voltage UA can be between 10 volts and 48 volts. In particular, the output voltage UA can have any value within this interval.

[0062] In particular, the input voltage UE, the output voltage UA, and the battery voltage U are involved. batt about a direct current voltage.

[0063] Since the electrical energy storage device 7 is used as a redundant power supply, a functional and, in particular, complete electrical connection 9 between the electrical energy storage device 7 and the vehicle electrical system 5 is important. This electrical connection 9 can be checked and evaluated to determine whether it is still sufficient or even completely disconnected. For this purpose, an electronic battery assessment system 10 can be used, for example. Using the battery assessment system 10, which can be described as an electronic system or electronic device, the electrical connection 9, or the connectivity of the electrical energy storage device 7 or the vehicle battery, can be verified.For this purpose, the battery assessment system 10 can, for example, include an evaluation unit 11, in particular an electronic evaluation unit. The evaluation unit 11 can, for example, be a computing unit. The electronic battery assessment system 10 can, for example, be a component of the vehicle 1, in particular of the vehicle electrical system 5. The electronic battery assessment system 10 can also be an independent unit or system.

[0064] To verify whether the electrical energy storage device 7 is still connected to the vehicle electrical system 5, the voltage converter 8 is activated. A control variable can be used for this purpose. In particular, a disturbance or excitation is applied to the voltage converter 8. Specifically, a disturbance frequency is applied via the voltage converter 8, particularly at a preceding time interval, in order to assess the electrical connection 9.

[0065] This can be achieved, in particular, by periodically changing the setpoint voltage UV of the voltage converter 8. Specifically, the setpoint voltage UV of the voltage converter 8 is periodically adjusted or varied. Using the setpoint voltage UV, the voltage converter 8 can be regulated or controlled in such a way that a desired output voltage UA is obtained. For example, a control unit 12 can be provided for changing the setpoint voltage UV. This unit can, for example, be part of the electronic battery assessment system 10. Using this control unit 12, the voltage converter 8 can be regulated and / or controlled.

[0066] In particular, the change in the setpoint voltage UV takes place within a specified time interval T (compare Fig. 2 and Fig. 3) This type of change in the supply voltage 12 can affect the battery voltage U batt and a battery current I batt can be influenced. For example, the voltage converter 8 can be considered a consumer or load of the electrical energy storage device 7. Thus, by changing the voltage converter 8 itself, a change in the electrical energy storage device 7 and, in particular, the tapped current can be varied. By changing the setpoint voltage UV over time, the consumption behavior of the electrical energy storage device 7 can change, so that the battery voltage I batt and the battery voltage U batt at least indirectly influenced.

[0067] For example, the setpoint voltage UV of the voltage converter 8 can be alternately increased or decreased by, for example, 0.05 volts at a predetermined time interval relative to the current voltage value. This deviation is sufficient to excite the electrical energy storage device 7 sufficiently to determine, for example, its internal resistance. The predetermined time interval T during which the setpoint voltage changes can be, for example, 100 milliseconds, or more specifically, between 20 milliseconds and 200 milliseconds. In particular, the time interval can be predetermined by the electronic battery evaluation system 10.

[0068] In order to assess the excitation generated by the changed target voltage UV, the battery current I can be measured within the time interval T. Batt and the battery voltage U BattThe values ​​are detected, measured, or recorded. A measuring device 13 can be used for this purpose. For example, the measuring device 13 can be designed as a higher-level detection unit by means of which both voltage and current can be measured or detected. It is also conceivable that the battery voltage UBatt is detected with a detection unit 14, in particular a first detection unit, and the battery current IBatt is detected with a detection unit 15, in particular a second detection unit 15. For example, the detection units 14, 15 can be part of the measuring device 13. In particular, the detection units 14, 15 can be part of the electronic battery assessment system 10 or the vehicle electrical system 5.

[0069] In particular, the battery voltage U Batt and the battery current I Batt captured in such a way that a temporal progression 16 (cf. Fig. 3) the battery voltage U Batt and a temporal progression 17 (cf. Fig. 2) of the battery current I Batt can be recorded or determined.

[0070] The two recorded or determined time courses 16, 17 can be compared or analyzed using the evaluation unit 11. The electrical connection 9 is then assessed using this comparison.

[0071] In this process, the two time profiles 16, 17 are compared in such a way as to check whether the two time profiles 16, 17 and thus the battery current I Batt and the battery voltage U Batt are in phase. If, after changing the setpoint voltage UV, the two time series 16, 17 are in phase, then there is an intact or correct electrical connection 9 between the electrical energy storage device 7 and the vehicle electrical system 5. Fig. 2 and Fig. 3. The time courses 16, 17 are in phase.

[0072] In particular, a predefined switching frequency can be used with the control unit 12 to adjust or change the setpoint voltage UV. Specifically, the switching frequency depends on the time interval T. For example, the switching frequency can be dependent on the time interval T. For example, the switching frequency can be determined from a reciprocal of the time interval T.

[0073] For example, to compare the time series 16, 17, the time series 16, 17 can be filtered by a digital filter 18. The digital filter 18 could, for example, be a bandpass filter. In particular, the time series 16, 17 can be pre-filtered using the digital filter 18. Specifically, using the acquisition unit 14, 15 or the evaluation unit 11, a step response can be generated as a time series 16, 17 of the battery voltage U immediately after changing the setpoint voltage UV. Batt and the battery current I BattThe target voltage can be determined. Furthermore, the setpoint voltage can be changed within the time interval T such that a voltage value of the target voltage UV is increased or decreased by a predetermined voltage value. In particular, the voltage value of the target voltage UV is periodically increased or decreased by a predetermined voltage value. This is determined, for example, using the control unit 12.

[0074] For example, the target voltage UV might currently have a value of 13.8 V. This value can be alternately increased or decreased by 0.05 V. In other words, the target voltage UV can be varied by 50 mV every 100 ms, alternating between the target and the setpoint. In this example, the target voltage would be set to 13.85 V for 100 ms and then to 13.75 V for 100 ms. This can be repeated periodically or continuously. This continues, in particular, until, for example, the electrical energy storage device 7 can be considered connected to the vehicle electrical system 5.

[0075] For example, by changing the setpoint voltage UV, the internal resistance of the electrical energy storage device 7 can be determined or stimulated. For determining the internal resistance, an average voltage of the time-dependent voltage profile 16 of the battery voltage U can be used. Batt and an average current of the time course 17 of the battery current I Batt This will be carried out. In particular, the internal resistance is determined using a ΔU. Batt / ΔI Batt -method or by the formula dU / dl.

[0076] In Fig. Figure 4 shows, for example, an exemplary curve of power and a quadratic current curve as well as a quadratic voltage curve of the battery with respect to the battery voltage U. Batt and the battery current I BattIn particular, the amounts of the changes are recorded here. This can also be used to check whether the excitation of the voltage transformer 8 with respect to the set voltage UV is sufficient.

[0077] For example, if the internal resistance is not constant, because the battery current I Batt Since the battery current varies statistically, there is no phase equality of the battery current I. Batt and the battery voltage U Batt If the excitation is insufficient, it is also likely that the electrical energy storage device 7 cannot be determined and can therefore be considered not present in the vehicle electrical system 5. If it is possible to determine the internal resistance and the step responses are in phase and sufficiently pronounced, then the electrical energy storage device 7 can be considered connected to the vehicle electrical system 5.

[0078] In particular, the specified voltage and current values ​​may be examples. Specifically, the specified current and voltage values ​​may be subject to measurement tolerances. Specifically, the specified current and voltage values ​​may have a deviation of 5%, particularly 10%. Reference symbol list 1 vehicle 2 electric drive unit 3 On-board electrical system 4 high-voltage batteries 5 On-board electrical system 6 components 7 electrical energy storage 8 voltage converters 9 electrical connection 10 electronic battery assessment system 11 evaluation unit 12 Control and / or regulating unit 13 Measuring device 14, 15 recording unit 16 Time course of the battery voltage 17 Time course of the battery current 18 digital filters I BattBattery power UA output voltage U Batt Battery voltage UE input voltage UV target voltage

Claims

[1] Method for assessing an electrical connection (9) of an electrical energy storage device (7) with an on-board network (5) of an at least partially electrically powered vehicle (1), wherein - the on-board electrical system (5) is supplied with electrical energy by the electrical energy storage device (7), and - with a voltage converter (8) of the vehicle electrical system (5), which is connected to the electrical energy storage device (7), at least one component (6) of the vehicle electrical system (5) is supplied with an output voltage (UA) of the voltage converter (8), comprising: - Changing a setpoint voltage (UV) of the voltage converter (8), with which the output voltage (UA) can be set, within a specified time interval (T), thereby generating a battery voltage (U Batt ) and a battery current (I Batt ) of the electrical energy storage device (7) can be influenced, - Detecting the battery voltage (U) Batt) of the electrical energy storage device (7) within the time interval (T) with a detection unit (14), - Recording the battery current (I Batt ) of the electrical energy storage device (7) within the time interval (T) with a detection unit (15), characterized by - Comparing a time course (16) of the battery voltage (U Batt ) and a time course (17) of the battery current (I Batt ) with an evaluation unit (11) - Assessing the electrical connection (9) of the electrical energy storage device (7) with the vehicle electrical system (5) depending on the compared time profiles (16, 17) of the battery voltage (U) Batt ) and the battery current (I Batt ) by the evaluation unit (11), wherein - when comparing the time profiles (16, 17) of the battery voltage (U Batt ) and the battery current (I Batt) is checked to see if these two time series (16, 17) are in phase. [2] Method according to claim 1, characterized by , that the set voltage (UV) is changed in the time interval (T) by increasing or decreasing a voltage value of the set voltage (UV) by a predetermined voltage value, in particular the voltage value of the set voltage (UV) is periodically increased or decreased by the predetermined voltage value. [3] Method according to any one of the preceding claims, characterized by , that by changing the setpoint voltage (UV) a determination of an internal resistance of the electrical energy storage device (7) is stimulated. [4] Method according to claim 3, characterized by , that the determination of the internal resistance depends on an average voltage of the time course (16) of the battery voltage (U Batt ) and an average current of the time course (17) of the battery current (I Batt ) is carried out. [5] Method according to any one of the preceding claims, characterized by , that the change of the setpoint voltage (UV) occurs depending on a specified switching frequency. [6] Method according to any one of the preceding claims, characterized by , that for comparing the time profiles (16) of the battery voltage (U Batt ) and the battery current (I Batt ) the time profiles (17) are filtered with a digital filter (18) depending on the changed input voltage (UV). [7] Method according to any one of the preceding claims, characterized by , that immediately after changing the set voltage (UV) a step response is obtained as a time course (16, 17) of the battery voltage (U) Batt ) and the battery current (I Batt ) is determined. [8] Electronic battery assessment system (10) comprising an evaluation unit (11) and at least one detection unit (14, 15), wherein the electronic battery assessment system (10) is configured to perform a method according to one of the preceding claims. [9] Vehicle (1) with an electronic battery assessment system (10) according to claim 8.

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