System and method for steady-state voltage estimation in battery system of vehicle

Abstract

A computer system (500) includes processing circuitry (502) configured to: measure an initial voltage V0 between a pole (106, 108) of a battery (110) in a vehicle and a ground potential of the vehicle; connecting a resistor (102, 104) between the pole of the battery and the ground potential (112); measuring at least two voltages V (t) on the resistor before the voltage reaches a steady-state voltage; fitting a predetermined voltage step response model to the at least two measured voltages and the initial voltage; estimating a steady-state voltage on the resistor based on the fitted voltage step response model; and determining an isolation resistance (114, 116) based on the estimated steady state voltage.

Description

Technical Field

[0001] The present disclosure generally relates to a high voltage power system for a vehicle. In particular aspects, the present disclosure relates to an estimation of a steady state voltage to determine the isolation resistance of a battery in a vehicle. The present disclosure may be applicable to any type of heavy vehicle including a high voltage power system, such as trucks, buses, and construction equipment, among other vehicle types. Although the present disclosure may be described with respect to a particular vehicle, the present disclosure is not limited to any particular vehicle. Background Art

[0002] In order to ensure the safety of the high voltage power system for the vehicle, it is necessary to measure the isolation resistance between the high voltage battery and the chassis ground. The isolation resistance measurement should be performed by selecting an appropriate measurement method, where an external voltage source or the vehicle's energy storage system can be used. This measurement can also be performed internally by the battery management system. The measurement of the isolation resistance can be obtained by inserting a known large test resistor between the battery pole and the ground potential and by measuring the voltage before and after the insertion of the test resistor in order to calculate the isolation resistance. Therefore, it is desirable to provide a reliable system and method for determining the isolation resistance in a vehicle. Summary of the invention

[0003] According to a first aspect of the present disclosure, a computer system is provided, the computer system comprising a processing circuit, the processing circuit being configured to: measure an initial voltage V between the respective positive and negative electrodes of a battery in a vehicle and the ground potential of the vehicle 0 + and V 0 - ; connecting a resistor between a pole of a battery and a ground potential; measuring at least two voltages V(t) on the resistor before the voltage reaches a steady-state voltage; fitting a predetermined voltage step response model to the at least two measured voltages and an initial voltage of the poles connecting the resistor; estimating the steady-state voltage on the resistor based on the fitted voltage step response model; and determining the isolation resistance based on the estimated steady-state voltage. The first aspect of the present disclosure may attempt to improve the measurement of the isolation resistance in a vehicle.

[0004] The technical benefits of the first aspect of the present disclosure may include that the isolation resistance can be measured quickly without waiting for the voltage across the resistor to reach a steady-state voltage. When the resistor is connected between the poles of the battery and ground, the voltage across the capacitor may take several seconds to reach a steady-state value, which is at least partially due to the capacitance in the system. Therefore, it is desirable to be able to determine the isolation resistance more quickly to avoid connecting the battery to the high-voltage bus before determining that the system is safe. By sampling the voltage across the resistor directly after connecting the resistor, a quick initial estimate of the isolation resistance can be provided.

[0005] Optionally, in some examples, including at least one preferred example, the processing circuit is further configured to: determine a quality metric of the fitted voltage step response model; compare the quality metric to a predetermined quality threshold; and discard fits where the quality metric is below the predetermined quality threshold. Technical benefits may include: not using an erroneous fit to estimate the steady-state voltage, thereby reducing the risk of incorrect isolation resistance estimation. There are many different ways to determine the quality of the fit, and any suitable way may be used to determine whether the quality of the fit is sufficient to determine the steady-state voltage.

[0006] Optionally, in some examples, including at least one preferred example, the processing circuit is further configured to: perform a second fit of a predetermined voltage step response model, the second fit being fit to a greater number of measured voltages than the first fit. Technical benefits may include: if the first fit is not good enough, a second fit may be used to achieve a fit that meets quality requirements, the second fit using a greater number of voltage samples. Steady-state voltage may thereby be estimated in order to determine isolation resistance.

[0007] Optionally, in some examples, including at least one preferred example, at least two voltages used to fit the voltage step response model are first voltage samples taken after connecting the resistor. Technical benefits may include: the isolation resistance may be determined quickly after connecting the resistor. It may be assumed that the sampling rate is significantly faster than the time required for the voltage to reach a steady-state voltage.

[0008] Optionally, in some examples, including at least one preferred example, the control circuit is further configured to control a transistor to connect the resistor. Technical benefits may include: using a transistor to enable fast switching to connect the resistor.

[0009] Optionally, in some examples, including at least one preferred example, the voltage step response model is V(t)=V SS +(V 0 -V SS ) (-t / τ) Description. Technical benefits may include measuring the initial voltage V 0 and a number of voltage samples V(t), a system of equations can be formed, where the time constant τ is determined, which in turn allows the steady-state voltage V to be estimated SS .

[0010] Optionally, in some examples, including at least one preferred example, the processing circuit is further configured to: determine a first isolation resistance between the positive electrode of the battery and ground; and determine a second isolation resistance between the negative electrode of the battery and ground. Technical benefits may include: ensuring that the isolation resistance of the two electrodes of the battery is sufficient before connecting the battery to the high voltage bus.

[0011] Optionally, in some examples, including at least one preferred example, the processing circuit is configured to control a voltage measurement unit arranged between a pole of the battery and a ground potential to measure at least two voltages across the resistor. Technical benefits may include: the isolation resistance may be conveniently determined using voltage measurements integrated in the vehicle power system.

[0012] Optionally, in some examples, including at least one preferred example, the computer system further comprises a filter configured to filter the at least two measured voltages to reduce noise. Technical benefits may include: the risk of erroneous estimation of steady-state voltage may be reduced.

[0013] Optionally, in some examples, including at least one preferred example, the processing circuit is configured to: measure an initial voltage V between the positive electrode of the battery and the ground 0 + ; Measure the initial voltage V between the negative pole of the battery and the ground 0 - ; connect a first resistor between the positive electrode of the battery and the ground potential; before the voltage reaches a steady-state voltage, measure a first set of at least two voltages on the first resistor; fit a predetermined voltage step response model to the first set of at least two voltages and the initial voltage; estimate the positive steady-state voltage on the first resistor based on the fitted voltage step response model; determine a first isolation resistor based on the estimated positive steady-state voltage; disconnect the first resistor; measure an initial voltage V between the negative electrode of the battery and the ground 0 - ; Measure the initial voltage V between the positive electrode of the battery and the ground 0 + ; connecting a second resistor between the negative electrode of the battery and the ground potential; measuring a second set of at least two voltages on the second resistor before the voltage reaches a steady-state voltage; fitting a predetermined voltage step response model to the second set of at least two voltages and the initial voltage; estimating a negative steady-state voltage on the second resistor based on the fitted voltage step response model; and determining a second isolation resistor based on the estimated negative steady-state voltage.

[0014] According to a second aspect of the present disclosure, a computer-implemented method is provided, the computer-implemented method comprising: measuring, by a processing circuit of a computer system, an initial voltage V between a positive electrode and a negative electrode of a battery and ground. 0 + and V 0 -; connecting a resistor between a pole of a battery and a ground potential; measuring at least two voltages V(t) on the resistor before the voltage reaches a steady-state voltage; fitting a predetermined voltage step response model to the at least two measured voltages and an initial voltage connecting the poles of the resistor; estimating the steady-state voltage on the resistor based on the fitted voltage step response model; and determining the isolation resistance based on the estimated steady-state voltage.

[0015] The technical effects, advantages and features of the second aspect of the present disclosure are largely similar to those described above in conjunction with the first aspect of the present disclosure.

[0016] The disclosed aspects, examples (including any preferred examples), and / or the appended claims may be appropriately combined with each other, which is obvious to any person skilled in the art. Additional features and advantages are disclosed in the detailed description, claims, and drawings, and in part will be obvious to those skilled in the art or recognized by practicing the disclosure as described herein.

[0017] Also disclosed herein are computer systems, control units, code modules, computer-implemented methods, computer-readable media, and computer program products associated with the technical benefits discussed above. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is an exemplary circuit diagram of a high-voltage battery system for a vehicle.

[0019] Figure 2 is an exemplary graph of a voltage step response for determining a steady-state voltage according to an example.

[0020] Figure 3 is an exemplary flow chart of a method for determining isolation resistance in an electrical system of a vehicle according to an example.

[0021] Figure 4 is an exemplary flow chart of a method for determining isolation resistance in an electrical system of a vehicle according to an example.

[0022] Figure 5 is a schematic diagram of an exemplary computer system for implementing the examples disclosed herein, according to an example.

[0023] Figure 6 is an exemplary circuit diagram of a high-voltage battery system for a vehicle. DETAILED DESCRIPTION

[0024] The detailed description set forth below provides information and examples of the disclosed technology in sufficient detail to enable those skilled in the art to practice the present disclosure.Examples are described in more detail below with reference to the accompanying drawings.

[0025] Figure 1 1 is an exemplary circuit diagram schematically showing a portion of a high voltage system 100 of a vehicle according to an example embodiment. The illustrated high voltage system 100 includes a battery 110 having a positive pole 106 and a negative pole 108 each connected to a ground potential 112. Between the respective poles and the ground there are corresponding resistors 102, 104 that can be connected via switches 118, 120. The resistors 102, 104 can be resistors, transistors, or any other suitable circuit element that provides a sufficiently high resistance. Isolation resistors 114, 116 between the respective battery poles 106, 108 and the ground 112 are also shown. In addition, the circuit diagram shows capacitances 126, 128 between the respective poles and the ground, which represent inherent system capacitances that cause a gradual increase in the voltage across the respective resistors 102, 104 when they are connected. The circuit also includes two voltage measurement units 122, 124 that are arranged to measure the voltage across the resistors 102, 104. However, it is also possible to use one voltage measuring unit which is arranged and configured to measure the voltage across the two resistors 102 , 104 , respectively.

[0026] In the following example, a description of a method for determining the isolation resistance will be given with reference to the isolation resistance 114 between the positive electrode 106 and the ground 112, and the isolation resistance 116 between the negative electrode 108 and the ground 112 can be similarly determined. Figure 2 and Figure 4 To describe this example, Figure 2 The voltage across the resistor is shown schematically as a function of time. Figure 4 is a flow chart outlining the general steps of a computer-implemented method according to an example.

[0027] The processing circuit is first configured to measure 300 an initial voltage V between the respective positive and negative electrodes 106 and 108 of the battery 110 in the vehicle and the ground potential of the vehicle. 0 + and V 0 - .exist Figure 2 The initial voltage V 0 + is shown as being equal to zero, but in reality the initial voltage may have a non-zero value. Next, the resistance 102 is connected 302 between the positive electrode 106 of the battery and the ground potential 112. The resistance 102 is shown here by a resistor 102, which is arranged between the positive electrode 106 of the battery and the ground 112 and connected 302 by closing the switch 118. The size of the resistor 120 to be connected depends on the battery voltage, and the size should be selected to ensure that connecting the test resistance does not cause a dangerous current, because the connection resistance will destroy the battery isolation. In general, the resistance should be significantly greater than 500 times the battery voltage.

[0028] Once the switch is connected, the voltage reaches the steady-state voltage V SS Previously, at least two voltages V(t) were measured 304 across resistor 102 . Figure 2 Two voltage measurements 202a-202b are shown taken before a steady-state voltage is reached. The sampling rate used to measure the voltage is typically in the millisecond range (such as 10 ms), while the time to reach a steady-state voltage is typically a few seconds. It should be noted that the time to reach a stable voltage depends on system parameters, such as the battery voltage and the actual isolation in the system, and the sampling rate is preferably selected to be significantly lower than the expected time to reach a steady-state voltage.

[0029] Next, the processing circuit is configured to fit 306 a predetermined voltage step response model to the at least two measured voltages and the initial voltage of the pole of the connecting resistor, which pole is here the positive pole 106. According to V(t)=V SS +(V 0 -V SS ) (-t / τ) , the predetermined voltage step response model can be described by a first-order system. By measuring the starting voltage V 0 and at least two additional voltages V(t), a system of equations may be established, allowing the steady-state voltage V to be estimated 308 based on the fitted voltage step response model. SS .

[0030] Once the steady-state voltage V is estimated SS , the isolation resistance (R 隔离 ) Determine 310 as R 隔离 = R 测试 / V SS (1+V 负 / V 正 )(V 正 -V SS ), where R 测试 A test resistor 102 is connected.

[0031] In this example, when the switch 118 on the positive electrode 106 is closed and the voltage is measured on the positive electrode 106 by the corresponding voltage measurement unit 122, the isolation resistance 116 on the negative side 108 is calculated using the determined voltage value. 隔离 Here, it is the isolation resistor 116 between the negative electrode 108 and the ground 112, R 测试 is the positive side test resistor 102, Vss is the positive electrode 106 steady-state voltage measured by the voltage measurement unit 122, V 正 is the initial voltage V of the positive electrode 106 measured by the voltage measuring unit 122 at the positive electrode 0 + , and V 负is the initial voltage V of the negative electrode 108 measured by the voltage measuring unit 124 on the negative electrode 108 0 - .

[0032] The isolation resistance 114 of the positive electrode 106 may then be determined in a similar manner by measuring the resistance 114 of the negative side 106 .

[0033] Thus, the described method and system provide a quick initial estimate of the isolation resistance before connecting the battery to the high voltage bus to ensure system safety. Since the voltage takes time to reach its steady state value, the measurement may not be completed before the battery is connected to the high voltage bus, which may create a safety risk or the risk of disconnecting the battery again after the external measurement.

[0034] Figure 4 A method is schematically shown in which a processing circuit is configured to determine 400 a quality metric of a fitted voltage step response model, compare the quality metric to a predetermined quality threshold 402, and discard 404 fits where the quality metric is below the predetermined quality threshold. The quality of the fit may be determined using a quality metric type of fit known to those skilled in the art, and the threshold may be set, for example, based on empirical testing to ensure that a poor fit does not result in an erroneous estimate of the steady-state voltage and, in turn, an erroneous estimate of the isolation resistance.

[0035] If it is determined that the quality of the fit is below a quality threshold, a second fit may be performed 406 in which the model is fit to a greater number of measured voltages. If the first fit or if a subsequent fit fails to meet the quality requirement of the fit, the actual steady-state voltage may also be waited for before determining the isolation resistance.

[0036] In addition, if the measured voltage signal is known to be noisy and if fitting is difficult or often fails, the measured voltage can be filtered, such as low-pass filtering the voltage signal or removing outliers. For example, outliers can be removed based on the difference between the measured sample and one or more previous samples. Filtering and removing outliers will likely require more than two measurement points, but using a fast measurement device with a high sampling rate, a fast estimate of the steady-state voltage can still be achieved.

[0037] Figure 5is a schematic diagram of a computer system 500 for implementing the examples disclosed herein. The computer system 500 is suitable for executing instructions from a computer-readable medium to perform these and / or any functions or processes described herein. The computer system 500 may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. Although only a single device is shown, the computer system 500 may include any device collection that executes an instruction set (or multiple instruction sets) individually or jointly to perform any one or more of the methods discussed herein. Therefore, any reference to a computer system, a computing system, a computer device, a computing device, a control system, a control unit, an electronic control unit (ECU), a processor device, a processing circuit, etc. in the present disclosure and / or claims includes a reference to one or more such devices to execute an instruction set (or multiple instruction sets) individually or jointly to perform any one or more of the methods discussed herein. For example, the control system may include a single control unit or multiple control units connected to each other or otherwise communicatively coupled, so that any executed function can be distributed between the control units as needed. In addition, such devices can communicate with each other or with other devices through various system architectures (such as directly or via a controller area network (CAN) bus, etc.).

[0038] The computer system 500 may include at least one computing device or electronic device that can include firmware, hardware and / or execute software instructions to implement the functionality described herein. The computer system 500 may include a processing circuit 502 (e.g., a processing circuit including one or more processor devices or control units), a memory 504, and a system bus 506. The computer system 500 may include at least one computing device having a processing circuit 502. The system bus 506 provides an interface for system components including, but not limited to, the memory 504 and the processing circuit 502. The processing circuit 502 may include any number of hardware components for performing data or signal processing or for executing computer code stored in the memory 504. The processing circuit 502 may include, for example, a general-purpose processor, a special-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a circuit containing a processing component, a group of distributed processing components, a group of distributed computers configured for processing, or other programmable logic devices designed to perform the functions described herein, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The processing circuit 502 may also include computer executable code that controls the operation of the programmable device.

[0039] The system bus 506 can be any of several types of bus structures, which can be further interconnected to a memory bus (with or without a memory controller), a peripheral bus, and / or a local bus using any of a variety of bus architectures. The memory 504 can be one or more devices for storing data and / or computer code to complete or facilitate the methods described herein. The memory 504 may include a database component, an object code component, a script component, or any type of information structure for supporting various activities herein. Any distributed or local memory device can be utilized with the systems and methods of the present specification. The memory 504 can be communicatively connected to the processing circuit 502 (e.g., via a circuit or any other wired, wireless, or network connection) and may include computer code for performing one or more processes described herein. The memory 504 may include nonvolatile memory 508 (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.) and volatile memory 510 (e.g., random access memory (RAM)), or any other medium that can be used to carry or store desired program code in the form of machine-executable instructions or data structures and that can be accessed by a computer or other machine having the processing circuit 502. A basic input / output system (BIOS) 512 may be stored in the nonvolatile memory 508 and may include the basic routines that help to transfer information between elements within the computer system 500.

[0040] The computer system 500 may also include or be coupled to non-transitory computer-readable storage media such as storage device 514, which may include, for example, an internal or external hard disk drive (HDD) (e.g., enhanced integrated drive electronics (EIDE) or serial advanced technology attachment (SATA)), a HDD for storage (e.g., EIDE or SATA), flash memory, etc. The storage device 514 and other drives associated with computer-readable and computer-usable media may provide non-volatile storage of data, data structures, computer-executable instructions, etc.

[0041] The hard-coded or soft-coded computer code may be provided in the form of one or more modules. The modules may be implemented as software and / or hard-coded in the circuit to implement the functionality described herein in whole or in part. These modules may be stored in a storage device 514 and / or a volatile memory 510 that may include an operating system 516 and / or one or more program modules 518. All or part of the examples disclosed herein may be implemented as a computer program 520 stored on a temporary or non-temporary computer-usable or computer-readable storage medium (e.g., a single medium or multiple media) such as a storage device 514, the computer program including complex programming instructions (e.g., complex computer-readable program code) that cause the processing circuit 502 to perform the actions described herein. Therefore, the computer-readable program code of the computer program 520 may include software instructions for implementing the functionality of the examples described herein when executed by the processing circuit 502. In some examples, storage device 514 may be a computer program product (e.g., a readable storage medium) having computer program 520 stored thereon, wherein at least a portion of computer program 520 may be loadable (e.g., loaded into a processor) for implementing the functionality of the examples described herein when executed by processing circuit 502. Processing circuit 502 may serve as a controller or control system of computer system 500 for implementing the functionality described herein.

[0042] The computer system 500 may include an input device interface 522 configured to receive input and selections to be transmitted to the computer system 500 when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices can be connected to the processing circuit 502 through an input device interface 522 coupled to the system bus 506, but can be connected through other interfaces such as a parallel port, an Institute of Electrical and Electronics Engineers (IEEE) 1394 serial port, a universal serial bus (USB) port, an IR interface, etc. The computer system 500 may include an output device interface 524 configured to forward output to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). The computer system 500 may include a communication interface 526 suitable for communicating with a network as appropriate or required.

[0043] The operational actions described in any of the exemplary aspects of this document are described to provide examples and discussions. The actions may be performed by hardware components, may be embodied in machine executable instructions to cause a processor to perform the actions, or may be performed by a combination of hardware and software. Although a specific order of method actions may be shown or described, the order of these actions may be different. In addition, two or more actions may be performed simultaneously or partially simultaneously.

[0044] Figure 6is a schematic circuit diagram representing a circuit 100 in a vehicle, wherein a processing circuit of a computer system is configured to: measure an initial voltage V between a positive electrode 106 and a negative electrode 108 of a battery 110 in the vehicle and a ground potential 112 of the vehicle 0 + and V 0 - ; connecting the corresponding resistors 102, 104 between the poles 102, 104 of the battery 110 and the ground potential 112; measuring at least two voltages V(t) on the resistors 102, 104 before the voltage reaches a steady-state voltage; fitting a predetermined voltage step response model to the at least two measured voltages and the initial voltage of the poles connected to the resistors; estimating the steady-state voltage on the resistors based on the fitted voltage step response model; and determining the isolation resistors 114, 116 based on the estimated steady-state voltage.

[0045] Example 1: A computer system comprising a processing circuit configured to: measure an initial voltage V between respective positive and negative electrodes of a battery in a vehicle and a ground potential of the vehicle 0 + and V 0 - ; connecting a resistor between the pole of the battery and the ground potential; measuring at least two voltages V(t) on the resistor before the voltage reaches a steady-state voltage; fitting a predetermined voltage step response model to the at least two measured voltages and the initial voltage connecting the pole of the resistor; estimating the steady-state voltage on the resistor based on the fitted voltage step response model; and determining the isolation resistance based on the estimated steady-state voltage.

[0046] Example 2. The computer system of Example 1, wherein the processing circuit is further configured to: determine a quality metric of the fitted voltage step response model; compare the quality metric to a predetermined quality threshold; and discard fits having a quality metric below the predetermined quality threshold.

[0047] Example 3. The computer system of Example 2, wherein the processing circuit is further configured to: perform a second fit of the predetermined voltage step response model, the second fit being fit to a greater number of measured voltages than the first fit.

[0048] Example 4. The computer system of any of the preceding examples, wherein the at least two voltages used to fit the voltage step response model are first voltage samples acquired after connecting the resistor.

[0049] Example 5. The computer system of any of the preceding examples, wherein the control circuit is further configured to control a transistor to connect the resistor.

[0050] Example 6. A computer system according to any one of the preceding examples, wherein the voltage step response model is given by V(t)=V SS +(V 0 -V SS ) (-t / τ) describe.

[0051] Example 7. The computer system of any of the preceding examples, wherein the processing circuit is further configured to: determine a first isolation resistance between a positive terminal of the battery and ground; and determine a second isolation resistance between a negative terminal of the battery and ground.

[0052] Example 8. The computer system according to any of the preceding examples, wherein the processing circuit is configured to control a voltage measuring unit arranged between a pole of the battery and the ground potential to measure the at least two voltages across the resistor.

[0053] Example 9. The computer system of any of the preceding examples, further comprising a filter configured to filter the at least two measured voltages to reduce noise.

[0054] Example 10. The computer system of Example 9, wherein the filter is configured to remove outliers based on a difference between the measured sample and one or more previous samples.

[0055] Example 11. A computer system according to any one of the preceding examples, wherein the processing circuit is configured to: measure an initial voltage V0 between the positive electrode of the battery and ground; + ; Measure the initial voltage V between the negative electrode of the battery and the ground 0 - ; connecting a first resistor (102) between the positive electrode (106) of the battery (104) and a ground potential (110); measuring a first group of at least two voltages on the first resistor before the voltage reaches a steady-state voltage; fitting the predetermined voltage step response model to the first group of at least two voltages; estimating a positive steady-state voltage on the first resistor based on the fitted voltage step response model; determining a first isolation resistor based on the estimated positive steady-state voltage; disconnecting the first resistor; and measuring an initial voltage V0 between the positive electrode of the battery and the ground. + ; Measure the initial voltage V0 between the negative electrode (108) of the battery and the ground -; connecting a second resistor (104) between the negative electrode of the battery and the ground potential; measuring a second set of at least two voltages on the second resistor before the voltage reaches a steady-state voltage; fitting the predetermined voltage step response model to the second set of at least two voltages; estimating a negative steady-state voltage on the second resistor based on the fitted voltage step response model; and determining a second isolation resistor based on the estimated negative steady-state voltage.

[0056] Example 12. A vehicle comprising a computer system according to any one of Examples 1 to 11.

[0057] Example 13. A computer-implemented method, the computer-implemented method comprising: measuring, by a processing circuit of a computer system, an initial voltage V between a terminal of a battery and ground 0 ; connecting a resistor between a battery pole and a ground potential; measuring at least two voltages V(t) on the resistor before the voltage reaches a steady-state voltage; fitting a predetermined voltage step response model to the at least two measured voltages; estimating the steady-state voltage on the resistor based on the fitted voltage step response model; and determining the isolation resistance based on the estimated steady-state voltage.

[0058] Example 14. The computer-implemented method of Example 13, further comprising: determining, by the processing circuit, a quality metric of the fitted voltage step response model; comparing the quality metric to a predetermined quality threshold; and discarding fits having a quality metric below the predetermined quality threshold.

[0059] Example 15. The method of Example 14, further comprising: performing (406), by the processing circuit, a second fit of the predetermined voltage step response model, the second fit being fit to a greater number of measured voltages than the first fit.

[0060] Example 16. The method according to any one of Examples 13 to 15, further comprising: determining, by the processing circuit, a first isolation resistance between the positive electrode of the battery and ground; and determining a second isolation resistance between the negative electrode of the battery and ground.

[0061] Example 17. The method according to any one of Examples 13 to 15, further comprising controlling a voltage measuring unit arranged between a pole of the battery and the ground potential to measure the at least two voltages across the resistor.

[0062] Example 18. The method of any one of Examples 13 to 17, further comprising filtering the at least two measured voltages to reduce noise.

[0063] Example 19. A computer program product comprising program code for performing the method according to any one of Examples 13 to 18 when executed by a processing circuit.

[0064] Example 20. A non-transitory computer-readable storage medium comprising instructions that, when executed by a processing circuit, cause the processing circuit to perform the method according to any one of Examples 13 to 18.

[0065] The terms used herein are only for the purpose of describing specific aspects and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "one", "a kind of" and "said" are intended to include the plural form as well. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It should also be understood that the terms "include" and / or "comprising" when used herein indicate the presence of stated features, integers, actions, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, parts and / or their groups.

[0066] It should be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0067] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element to another element, as shown in the figures. It should be understood that these terms and those discussed above are intended to cover different device orientations in addition to the orientations depicted in the figures. It should be understood that when an element is referred to as being "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or there may be intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0068] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It should also be understood that, unless otherwise clearly defined herein, the terms used herein should be interpreted as meanings consistent with their meanings in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense.

[0069] It should be understood that the present disclosure is not limited to the aspects described above and shown in the accompanying drawings; rather, the skilled person will recognize that many changes and modifications can be made within the scope of the present disclosure and the attached examples. In the drawings and description, various aspects have been disclosed for the purpose of illustration only and not for the purpose of limitation, and the scope of the present disclosure is set forth in the attached examples.

Claims

1. A computer system (500), the computer system comprising a processing circuit (502), the processing circuit being configured to: Measuring an initial voltage V0 between respective positive and negative electrodes (106, 108) of a battery (110) in a vehicle and a ground potential of the vehicle + and V0 - ; Connecting a resistor (102, 104) between one pole of the battery and the ground potential (112); measuring at least two voltages V(t) across the resistor before the voltage reaches a steady-state voltage; fitting a predetermined voltage step response model to the at least two measured voltages and the initial voltage connecting the poles of the resistor; estimating a steady-state voltage across the resistor based on the fitted voltage step response model; as well as An isolation resistance (114, 116) is determined based on the estimated steady-state voltage.

2. The computer system of claim 1 , wherein the processing circuit is further configured to: determining a quality metric of the fitted voltage step response model; comparing the quality metric to a predetermined quality threshold; and Fits having a quality metric below the predetermined quality threshold are discarded.

3. The computer system of claim 2, wherein the processing circuit is further configured to: A second fit of the predetermined voltage step response model is performed, the second fit being fit to a greater number of measured voltages than the first fit.

4. The computer system of any one of the preceding claims, wherein the at least two voltages used to fit the voltage step response model are first voltage samples acquired after connecting the resistor.

5. The computer system of any one of the preceding claims, wherein the control circuit is further configured to control a transistor to connect the resistor.

6. The computer system according to any one of the preceding claims, wherein the voltage step response model is given by V(t)=V SS +(V0-V SS ) (-t / τ) describe.

7. The computer system of any one of the preceding claims, wherein the processing circuit is further configured to: determining a first isolation resistance (114) between a positive terminal of the battery and ground; and A second isolation resistance (116) between the negative terminal of the battery and ground is determined.

8. The computer system according to any of the preceding claims, wherein the processing circuit is configured to control a voltage measuring unit (122, 124) arranged between a pole of the battery and the ground potential to measure the at least two voltages across the resistor.

9. The computer system of any one of the preceding claims, further comprising a filter configured to filter the at least two measured voltages to reduce noise.

10. The computer system of claim 9, wherein the filter is configured to remove outliers based on a difference between a measured sample and one or more previous samples.

11. The computer system of any preceding claim, wherein the processing circuit is configured to: Measure the initial voltage V0 between the positive electrode of the battery and the ground + ; Measure the initial voltage V0 between the negative electrode of the battery and the ground - ; Connecting a first resistor (102) between the positive electrode (106) of the battery (104) and a ground potential (110); measuring a first set of at least two voltages across the first resistor before the voltage reaches a steady-state voltage; Fitting the predetermined voltage step response model to the first group of at least two voltages and the initial voltage V0+; estimating a positive steady-state voltage across the first resistor based on the fitted voltage step response model; determining a first isolation resistance based on the estimated positive steady-state voltage; disconnecting the first resistor; Measure the initial voltage V0 between the negative electrode (108) of the battery and the ground - ; Measure the initial voltage V0 between the positive electrode of the battery and the ground + ; Connecting a second resistor (104) between the negative electrode of the battery and the ground potential; measuring a second set of at least two voltages across the second resistor before the voltage reaches a steady-state voltage; Fitting the predetermined voltage step response model to the second set of at least two voltages and the initial voltage V0 - ; estimating a negative steady-state voltage across the second resistor based on the fitted voltage step response model; as well as A second isolation resistance is determined based on the estimated negative steady-state voltage.

12. A vehicle comprising a computer system according to any one of claims 1 to 11.

13. A computer-implemented method, the computer-implemented method comprising: The processing circuit of the computer system measures (300) the initial voltage V0 between the respective positive and negative electrodes of the battery and the ground. + and V0 - ; Connecting (302) the resistor (102, 104) between the poles (106, 108) of the battery (110) and a ground potential (112); Before the voltage reaches a steady-state voltage, measuring (304) at least two voltages V(t) across the resistor; fitting (306) a predetermined voltage step response model to the at least two measured voltages and the initial voltage connecting the poles of the resistor; estimating (308) a steady-state voltage across the resistor based on the fitted voltage step response model; as well as An isolation resistance (114, 116) is determined (310) based on the estimated steady-state voltage.

14. A computer program product comprising program code for performing the method according to claim 13 when executed by a processing circuit.

15. A non-transitory computer-readable storage medium comprising instructions which, when executed by a processing circuit, cause the processing circuit to perform the method of claim 13.

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