Method for operating an on-board power system

Abstract

The invention relates to a method for operating an on-board power system (50) having an energy store and an electronic load distributor (72), wherein a sensor-computing unit is assigned to the energy store, wherein at least one measured variable of the energy store is detected using the sensor-computing unit and a parameter of the energy store is calculated taking into account the at least one measured variable, wherein a check of the at least one measured variable is carried out in a first step and a check of the calculation is carried out in a second step, for which the electronic load distributor (72) is used.

Description

Technical Field

[0001] The present invention relates to a method for operating an on-board electrical network and such an on-board electrical network. Background Technology

[0002] In automotive applications, the vehicle electrical network should refer to the totality of all electrical components in the vehicle. Therefore, it includes not only electrical loads but also power sources, such as batteries. Here, a distinction is made between the energy vehicle electrical network and the communication vehicle electrical network, with a focus on the energy vehicle electrical network responsible for supplying energy to the vehicle's components. Microcontrollers are typically installed to control the vehicle electrical network, performing both control and monitoring functions.

[0003] In motor vehicles, it should be noted that electrical power is available, enabling the vehicle to be started at any time and providing sufficient current during operation. However, even when the vehicle is stationary, the electrical load should still be able to operate for a reasonable period of time without affecting subsequent starting.

[0004] The increasing electrification of assemblies and the introduction of new vehicle functions, such as partially automated, highly automated, or fully automated driving, have raised the requirements for the reliability of electrical power supply in motor vehicles. Particular attention should be paid to the continuously increasing number of power electrical systems. If one of these systems malfunctions or even fails, it could cause the onboard electrical grid voltage to operate outside the normal operating range, potentially compromising the comfort and safety of vehicle occupants.

[0005] Exemplary new driving functions include automated driving and autonomous driving. In automated and autonomous driving operations in motor vehicles, the driver is no longer available as a sensory, regulatory, mechanical, and energy backup. The vehicle must independently identify its environment, plan a trajectory, select a trajectory, and execute the trajectory through the manipulation of actuators. Since the driver is eliminated, the vehicle, i.e., the manufacturer, is responsible for vehicle performance. Summary of the Invention

[0006] Against this backdrop, a method and an onboard electrical grid are presented. Embodiments are derived from the dependent claims and the specification.

[0007] The described method is used to operate an onboard electrical network having an energy storage device, such as a battery, and an electronic power divider or load divider. A sensor-computing unit is allocated to the energy storage device, wherein the sensor-computing unit detects at least one measurement parameter of the energy storage device and calculates parameters of the energy storage device taking into account the at least one measurement parameter. Verification of the at least one measurement parameter is performed in a first step. Verification of the calculation is performed in a second step. An electronic load divider is used for this purpose.

[0008] It can be specified that, in the first step, a verification of the at least one measurement parameter is performed once per driving cycle, and in the second step, a verification of the calculation is performed multiple times per driving cycle.

[0009] In this design, the method specifies monitoring the effective power of the battery to ASIL C by using an electronic battery sensor (EBS) as a sensor-computing unit and an intelligent electronic power divider or load divider. The EBS provides information about the battery state, taking into account aging effects, when necessary. The power divider has the task of transferring electrical energy to components in the vehicle's electrical network. It should also be noted that the electronic battery sensor (EBS) may not achieve the required systemic safety integrity, such as ASIL C or the hardware metrics provided to it. Verifying the EBS via the power divider is a feasible solution to this problem.

[0010] The method described has a number of advantages, at least in some of the embodiments:

[0011] - Enables a single-channel ASIL C energy vehicle grid without an additional 12V battery.

[0012] - No additional measures are needed in the vehicle-mounted electrical network because, due to other functions, such as the separation of loads with functions unrelated to safety, an intelligent power divider or safety measures that meet the same functions should be integrated anyway.

[0013] Other advantages and design solutions of the present invention are derived from the specification and drawings.

[0014] It goes without saying that the features mentioned above and explained below can be used not only in combinations described separately, but also in other combinations or individually, without departing from the scope of the invention. Attached Figure Description

[0015] In the attached image:

[0016] Figure 1 This illustrates an onboard electrical grid according to existing technology;

[0017] Figure 2 One implementation of the described vehicle-mounted electrical grid is shown;

[0018] Figure 3 An exemplary implementation of the described method is shown;

[0019] Figure 4 A flowchart illustrates a feasible verification method for EBS measurement parameters;

[0020] Figure 5 A cut-off portion of the vehicle-mounted electrical grid is shown to illustrate the verification of the measurement parameters;

[0021] Figure 6 An exemplary current pulse of a DC-DC voltage converter is illustrated graphically.

[0022] Figure 7 A flowchart illustrates a feasible check of the internal resistance of the battery in the vehicle's electrical network.

[0023] Figure 8 The verification of the calculated battery internal resistance is shown. Detailed Implementation

[0024] The present invention is illustrated schematically with reference to the accompanying drawings, and will be described in detail below with reference to the drawings.

[0025] Figure 1 An exemplary 12-volt onboard electrical network for a manually driven vehicle is shown, generally indicated by reference numeral 10. The illustration shows a generator 12 and a 12V load R as components of the onboard electrical network 10. B,12V 14. Safety-related load R SR 16. Starter S18 and 12V battery 20.

[0026] It should be noted that in current vehicle electrical systems, ASIL B is distributed to the supply of safety-related loads, for example. This ensures a reliable energy supply from battery 20 via ASIL B.

[0027] However, it should be considered that the safety requirements for energy supply in vehicles are continuously increasing. In manual driving, this is due to factors such as heavier vehicles, like BEVs (Battery Electrical Vehicles) with 800kg batteries (which may have a total mass exceeding 3 tons), the trend towards larger vehicles, and the associated poorer controllability when steering assist is lost. To achieve braking or steering assist, electrical energy from the onboard energy grid is required, thus increasing the requirements for electrical supply, for example, to ASIL C.

[0028] To ensure high safety requirements for energy supply, specific batteries and their associated monitoring devices are primarily used in the safety scheme. This is to monitor the battery's power capacity or performance, for example, by determining the internal resistance Ri of the battery 20. The monitored battery 20 is used to ensure that risks arising during manual or autonomous driving are kept below the permissible residual risk due to a failure of the onboard energy grid.

[0029] For example, to ensure that security-related loads are protected using ASIL C, Figure 1 For a safe energy supply at medium load 16, the use of EBS is no longer sufficient, because the EBS may need to be systematically developed to the maximum extent according to ASIL B, or the required hardware specifications cannot be achieved using EBS alone. In order to ensure the battery's energy supply according to ASIL C, a new approach based on ASIL C has been proposed. Figure 2 One implementation method of vehicle-mounted electrical grid.

[0030] Figure 2 An onboard electrical network is shown, generally indicated by reference numeral 50. This onboard electrical network 50 includes a motor EM 52 and a high-voltage / 48V battery B on a side 51 having a higher voltage level. HV / 48V 56. HV / 48V load R B,HV / 48V 58 and DC-DC voltage converter 60. A switch 54 is integrated into the lithium-ion battery to prevent overcurrent and thus for thermal self-protection. On the side 67 with a low voltage level, a 12V load R representing multiple 12V non-safety-independent loads (NSRV) is provided. B,12V 70. Electronic load divider; 72. Conventional power divider or fuse box; 73. Safety-related load; 74. Safety-related load; 76. Sub-power divider; 78. Safety-related / rear-collision / NSRV load; 80. Battery B1; 82. Sensors associated with battery B1; 84. For monitoring.

[0031] Therefore, in this implementation, battery monitoring is carried out using ASIL C via EBS 84 in conjunction with an intelligent load divider (IELV) 72. However, difficulties arise in monitoring EBS 84 via IELV 72 in the described vehicle electrical grid 50 (also referred to herein as the energy vehicle electrical grid), which arises from unknown current consumption occurring between battery 82 and IELV 72.

[0032] To monitor battery 82, the main focus is to determine the internal resistance R of battery 82. iTherefore, the EBS 84 is used in the vehicle electrical network 50. Because the EBS 84 does not achieve systemic safety integrity, such as ASIL C and / or the required hardware measurements, verification is performed via the intelligent IELV 72. This is due to unknown losses between the relevant IELV measurement points and the battery 82. This is not unimportant. Therefore, a two-phase approach is used, in Figure 3 The proposal was discussed in China.

[0033] As an alternative, the method can also be used in vehicle electrical systems with only one voltage level, such as 12V.

[0034] Figure 3 Exemplary embodiments of a first driving cycle 100 and a second driving cycle 102 are shown. First symbol 104 indicates verification of EBS measurement parameters, and second symbol 106 indicates the internal resistance R of the battery. i Verification of the calculations.

[0035] In the first step, the accuracy of the EBS measurement is checked. Here, regarding the R... i The key measurement parameters are verified. This verification is performed once per driving cycle.

[0036] In the second step, the EBS is used to check the R i The accuracy of the calculations is verified. This check on the EBS calculations is performed multiple times during the driving cycle in order to identify errors in the EBS in a timely manner before safety objectives are violated.

[0037] Therefore, a two-stage approach is proposed, and the two stages will be discussed in detail below.

[0038] In Phase 1, the measurement parameters of the EBS are verified. This is to calculate the battery's internal resistance R. i The following measurement parameters are mainly required:

[0039] - Current measurement, where the main concern is the current step, and the offset can be ignored.

[0040] - Voltage measurement, which is mainly related to voltage step, can ignore offset.

[0041] It should be noted that the aforementioned verification should be used to identify erroneous measurements of the EBS regarding current and voltage drift. For this purpose, a method is set up according to... Figure 4 The handling method and according to Figure 5 The signal flow.

[0042] Figure 4A flowchart illustrates a feasible procedure for verifying the EBS measurement parameters. In a first step 150, the battery current is excited, for example, via a DC-DC voltage converter. Subsequently, in a second step 152, voltage and current measurements are performed according to ASIL A(C) via an electronic load divider (IELV) 154. In parallel with this, in step 154, voltage and current measurements are performed via the EBS according to ASIL B(C), and then in step 156, the measured voltage and current values ​​are transmitted to the IELV with ASIL B(C).

[0043] Then, in step 160, the IELV calculates the value for ΔU based on ASIL C. EBS ΔI EBS and ΔU IELV ΔI IELV The value. Then, in step 162, the IELV adjusts ΔU according to ASIL C. EBS ΔI EBS and ΔU IELV ΔI IELV A comparison is made. If the difference between the values ​​of EBS and IELV exceeds a threshold, a fault state is established. Then, in step 164, the IELV sends the state to the higher-level ECU using ASIL C. ASIL C must be used to avoid erroneous communication.

[0044] The erroneous communication in the IELV must be identified by the higher-level ECU in ASIL C during parallel step 170. Furthermore, in the IELV, periodic stimuli, a prerequisite for battery state identification, are monitored according to ASIL C, and in the event of erroneous stimuli, communication is made with the higher-level ECU in ASIL C. The higher-level ECU then takes action, such as triggering a stimulus or transitioning to a safe state.

[0045] In addition, in step 180, missing or erroneous communications of the EBS are detected by IELV according to ASIL C.

[0046] Figure 5 It shows Figure 2 The side 67 with the low voltage level is connected to the signal flow used to illustrate the verification of the measured parameters. The diagram shows the coupled DC-DC voltage converter 60 and the 12V load R. B,12V70. Electronic load divider (IELV) 72. Conventional power divider or fuse box 73. Safety-related load 74. Safety-related load 76. Power divider 78. Safety-related / rear-collision / NSRV load 80. Battery B1 82 and EBS 84 associated with battery B1 82. Figure 190 shows the current signal pre-given by the DC-DC voltage converter.

[0047] The signal flows will now be discussed in detail, where the numbering is not intended to specify a chronological order. The first signal flow 192, as information 194, transmits U and I from EBS 84 to a higher-level controller 196, such as an electronic energy management system (EEM), according to ASIL B(C). The second signal flow 200, as information 202, transmits U and I from EBS 84 to IELV 72 according to ASIL B(C), where U and I are verified 204 according to ASIL C. The third signal flow 210, as information 212, transmits U and I according to ASIL A(C) for verification 204 in IELV 72. Current values ​​are typically determined from the main / auxiliary switch measurement point, and voltage values ​​are typically determined at a point in the IELV. A fourth signal flow 220, containing information 222 regarding the reliability of the stated values, flows from verification 204 to the higher-level controller 196.

[0048] Figure 6 An exemplary current pulse of a DC-DC voltage converter is shown in Figure 250, with time t plotted on the horizontal axis 252 and current I plotted on its vertical axis 254.

[0049] To monitor battery status, a certain excitation, such as a current peak, is required. Depending on the operating strategy and vehicle usage, these excitations are infrequent in the vehicle's electrical network, thus intermittent monitoring of battery status is not possible. To infer these diagnostic gaps, an active excitation is applied to the vehicle's electrical network. This can be done, for example, by a DC-DC voltage converter that, for a defined duration of a defined current pulse, applies an excitation according to... Figure 6 A rectangular pulse of current is applied to the vehicle's electrical network. The IELV must ensure, via ASIL C, that the excitation occurs at a sufficient frequency (otherwise, a notification must be sent to the higher-level controller), that is, the correctness of the ASIL C signal, and the monitoring of communication via ASIL C by the higher-level controller.

[0050] The excitation can also be achieved in other ways, such as by switching on and off high loads.

[0051] The EBS uses its original ASIL B(C) signal U EBS I EBST EBS The signal is sent to an intelligent power distributor. This power distributor measures U at a specific operating point, namely when the test pulse is applied as described above, with ASIL A(C) quality. IELV I IELV T IELV The increment is identified in the intelligent electronic load divider and compared with the increment of IELV to ASIL C integrity. In this way, it can be determined whether the EBS measurement is error-free and thus the EBS measurement signal is elevated to ASIL C integrity.

[0052] Alternatively, the EBS has sent the incremental value to the IELV. The IELV itself identifies the incremental value and compares it.

[0053] When comparing measured values, the current at the output of a conventional power divider should be taken into account as a decisive disturbance parameter; see [reference needed]. Figure 2 This is because the current cannot be directly measured. When comparing the current and voltage increments on the IELV- and EBS sides, the constant current flowing through the conventional distributor is eliminated through incremental calculation. Only load fluctuations present at the moment of the test pulse interfere with the comparison. To minimize the impact of such interference, the following measures can be taken:

[0054] - The test is performed during the vehicle's initialization phase or while the vehicle is inertial driving, in order to minimize the number of active systems or actuators;

[0055] - Generates a test signal that can evaluate multiple edges. Switching edges that occur randomly on a conventional load divider side will not have the same effect on all edges, thus filtering out interference when comparing multiple edges sequentially and when using a 1-out-of-N approach;

[0056] - If the measured data from the test are inconsistent, the test can be repeated multiple times to improve the reliability of the conclusions; - Interference caused by load edges on a conventional power divider may lead to defects in the measurement chain due to misidentification, causing a shift towards a safe state. That is, the system is safe in principle, and misdiagnosis only leads to a reduction in availability.

[0057] The IELV sends the information from the correctly measured EBS 84 to the higher-level controller 196. Alternatively, in a simpler implementation, it can be specified that previously unknown current outflows or battery currents can be measured via additional measurement points.

[0058] Measurements of physical parameters in IELV can be calculated directly at the junction of the battery path in IELV or by calculation according to the node rules and mesh rules in IELV. Furthermore, sensing circuits or similar devices with direct measurement capabilities can be installed on the battery.

[0059] This is achieved by verifying the measurement parameters of EBS at this point, ensuring that the signals necessary for evaluating the battery's power capability are present in ASIL C quality.

[0060] The following section discusses Phase 2, in which the EBS performance parameters are verified.

[0061] Figure 7 Therefore, the flowchart shows the method for checking the battery's internal resistance R. i The correctness of the process is as follows: In the first step 300, the battery current is excited by a DC-DC voltage converter. In the subsequent step 302, voltage and current are measured by EBS according to ASIL B(C). Then, in step 304, the EBS calculates R using ASIL B(C). i Then, in step 306, the measured voltage and current values, along with R, are calculated according to ASIL B(C). iEBS The data is transmitted to IELV. Then, in step 308, IELV calculates R based on the EBS voltage and current measurements according to ASIL A(C). IELV Subsequently, in step 310, the IELV compares R... iEBS and R IELV Then, in step 312, the IELV sends the status to the higher-level ECU in ASIL C. ASIL C must be used to prevent erroneous communication.

[0062] Furthermore, in steps 320 and 340, ASIL C is used to detect missing or erroneous communication with the higher-level ECU. In step 322, the IELV monitors stimuli sufficiently frequently using ASIL C, and communicates with the higher-level ECU using ASIL C in the absence of stimuli. This enables actions by the higher-level ECU, such as triggering stimuli or transitioning to a safe state.

[0063] Furthermore, in step 330, the IELV uses ASIL C to detect missing or invalid communication in the EBS.

[0064] It should be noted that R should be identified within a short time interval. i This is so that, for example, a single-pool short circuit can be identified. Figure 7 The process for this verification is illustrated in [the document]. For R... iSpecifically, sufficient excitation is also required in vehicle-mounted power grids or energy vehicle-mounted power grids. This excitation can be implemented as described above. The EBS identifies the current-voltage variation curves and calculates R. i The EBS not only includes the raw data but also the calculated R... iEBS Send to IELV.

[0065] Because bus systems, such as LIN, have very limited transmission rates, data in the EBS is sent as packets. The LIN communication cannot transmit all measurement data in real time. The EBS therefore has an identification mechanism that recognizes the occurrence of current edges. The EBS then stores the required current and voltage values, filtering the values ​​if necessary. The EBS continues to calculate R independently of this mechanism. i The data and R iEBS These are then sent as data packets. Alternatively, each individual measurement can also be sent, for example, through different communication interfaces.

[0066] The IELV calculation R iIELV And this will determine whether the EBS has been calculated correctly. The IELV will R i The status of the system is sent to the upper-level controller, such as the energy management system.

[0067] In order to implement precise R i It is determined that multiple excitation edges are needed. These excitation edges are sent to the IELV and evaluated. To achieve diverse redundancy, different algorithms can be used in EBS and / or IELV to determine R. i Alternatively, the algorithm can be developed according to ASIL C.

[0068] It should be noted that the methods described can also be used for other ASIL classifications in principle.

[0069] Figure 8 It shows Figure 5 The low-voltage side is used to illustrate the verification of the Ri calculation. The first signal stream 400 carries R as information 402 according to ASIL B(C). i The second signal stream 410, as information 412, carries R according to ASIL B(C). iEBS U, I. The third signal stream 420, as information 422, carries an indication of whether the value is reliable. In 430, R is calculated based on U, I in the IELV72. iIELV And according to ASIL C for R iEBS and R iIELV Verification is required.

[0070] It should be considered that if no other load divider is placed between the battery and the IELV, the method can be implemented more easily. Then, R can be implemented directly in the IELV. i In other words, measurements are performed directly in IELV using ASIL C, since the LIN communication is eliminated. This also applies to the selection of other communication systems with higher data transmission rates and, if necessary, real-time capabilities. Furthermore, the EBS can connect directly to the IELV, or it can communicate with the IELV through other controllers, such as gateways.

Claims

1. A method for operating an on-board electrical network (50), the on-board electrical network having an energy storage device and an electronic power divider (72), wherein a sensor-computing unit is allocated to the energy storage device, wherein at least one measurement parameter of the energy storage device is detected by the sensor-computing unit, and a parameter of the energy storage device is calculated in consideration of the at least one measurement parameter, wherein the internal resistance of the energy storage device is calculated as the parameter, wherein verification of the at least one measurement parameter is performed in a first step, and verification of the calculation is performed in a second step, for which the electronic power divider (72) is used.

2. The method according to claim 1, wherein in the first step, a verification of the at least one measurement parameter is performed once per driving cycle, and in the second step, a verification of the calculation is performed multiple times per driving cycle.

3. The method according to claim 1 or 2, wherein a battery (82) is used as an energy storage device and a battery sensor (84) that distributes electrons to the battery is used as a sensor-computing unit.

4. The method according to claim 1 or 2, wherein the detected current and voltage are used as the measurement parameters.

5. The method of claim 4, wherein the current step and voltage step are detected as the measurement parameters.

6. The method of claim 1 or 2, wherein multiple excitation edges are taken into account in order to calculate the internal resistance.

7. The method according to claim 1 or 2, wherein the method is performed during the initialization phase.

8. The method according to claim 1 or 2, wherein the method is performed during the inertial motion of the vehicle.

9. The method according to claim 1 or 2, wherein a test signal is given in advance for carrying out the method.

10. The method according to claim 1 or 2, wherein the results of the two verifications are forwarded to the superior computing unit.

11. An on-board electrical network having an energy storage device with a sensor-computing unit and an electronic power divider (72), wherein the on-board electrical network (50) is configured to implement the method according to any one of claims 1 to 10.

12. The vehicle-mounted electrical network according to claim 11, comprising a side (51) having a high voltage level and a side (67) having a low voltage level, wherein the energy storage device and the power divider (72) of the electronics are disposed on the side (67) having a low voltage level.

13. The vehicle-mounted electrical network according to claim 11 or 12, wherein the energy storage device is configured as a battery (82) and the sensor-computing unit is configured as an electronic battery sensor (84).

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