Method for determining a cable resistance in a vehicle and vehicle

Abstract

The present disclosure relates to a method of determining a cable resistance in a vehicle (1), comprising: calculating (S1) a cable resistance based on a resistivity of a cable material, a cable length and a cable cross-sectional area; calculating (S2) a corrected resistance value (R (T)) on the basis of the theoretical temperature of the cable when the current flows; measuring (S3) a real-time voltage drop between two points along the cable and calculating a measured real-time resistance of the cable; periodically comparing the actually measured real-time resistance with the corrected resistance value at predetermined time intervals (S4); and providing (S5) a fault signal if the difference between the measured real-time resistance value and the corrected resistance value is above a predetermined threshold value. The present disclosure also relates to a vehicle (1).

Description

Technical Field

[0001] The present disclosure relates to a method of determining a cable resistance in a vehicle and to a vehicle. More particularly, the present disclosure relates to a method of determining a cable resistance in a vehicle and to a vehicle as defined in the preambles of the independent claims. Background Art

[0002] In all electric and conventional vehicles, electrical control units (ECUs) and vehicle components rely on electrical power. Designing the system current and voltage performance provided by the power supply plays a crucial role in ensuring the loads are fully functional. As the automotive industry and nearly all original equipment manufacturers (OEMs) are moving towards increasing vehicle electrification, the number of electrical components in each vehicle will increase. This trend is further driven by the increasing number of safety-critical functions being implemented, and the electrification of previously mechanical systems such as steering, braking, and autonomous driving systems. This increases the performance requirements and safety levels (ASILs) of vehicle electrical systems.

[0003] The above industry changes have further led to increased current consumption and higher power requirements for power supply systems. In addition, the introduction of different levels of autonomous driving systems (ADAS) has significantly increased the demand for high-performance and stable DC power from DC-DC converters and batteries, as well as the requirements for cable harness resistance and power availability.

[0004] In many cases, the focus is on designing a system that has sufficient DC power to deliver to the electrical load at a stable voltage level and provide a robust power rate. However, there is a parameter between the electrical load and the power supply that is largely overlooked. The cable bundle and its resistance / impedance cause a voltage drop that affects every component.

[0005] This voltage drop caused by cable harness resistance is only considered at the outset of a project when designing the power distribution and supply. The cable resistance is determined based on the material used, cross-sectional area, and length. This value is then set as a fixed parameter. There is no subsequent monitoring or testing of the system to analyze how the cable resistance changes over time and its impact on system voltage quality and voltage drop based on the current flowing through the cables.

[0006] Therefore, as the electrification of vehicles continues to advance, there is a need for improved methods of controlling electrical devices in vehicles. Summary of the Invention

[0007] The present disclosure is directed to alleviating, mitigating, or eliminating one or more of the aforementioned deficiencies and shortcomings of the prior art, and at least resolving the aforementioned problems. According to a first aspect, a method for determining cable resistance in a vehicle is provided, comprising: calculating the cable resistance based on the resistivity of the cable material, the cable length, and the cable cross-sectional area; calculating a corrected resistance value (RT) based on the theoretical temperature of the cable under a current flowing through the cable; measuring a real-time voltage drop between two points along the cable and calculating the measured real-time resistance of the cable; periodically comparing the measured real-time resistance with the corrected resistance value at predetermined time intervals; and providing a fault signal if the difference between the measured real-time resistance and the corrected resistance value is above a predetermined threshold.

[0008] The problems of the prior art are thus solved. By regularly comparing the measured real-time resistance with the calibrated resistance value at predetermined time intervals and providing a fault signal if the difference between the measured real-time resistance and the calibrated resistance value is higher than a predetermined threshold, the vehicle owner or operator is warned that the cables in the vehicle electrical system are deteriorating or even no longer meet safety standards.

[0009] According to some embodiments, the cable resistance is calculated as the resistivity of the cable material multiplied by the cable length divided by the cable cross-sectional area (ρ*L / A[Ω]). This allows for accurate cable resistance.

[0010] According to some embodiments, the correction resistance value (R(T)) is calculated as follows:

[0011] R(T)=R Ref (1+α(T Op -T Ref )), where T Ref is the reference temperature, α is the temperature coefficient of resistance of the cable's conductor material, T Op is the operating temperature during conduction. This allows accurate estimation of the correction resistance value (R(T)).

[0012] According to some embodiments, the fault signal is provided to the vehicle electronic control unit as a diagnostic trouble code. Thus, standardized equipment in the vehicle, such as an infotainment system or dashboard instrumentation, can be used to transmit the fault signal to the vehicle owner or operator.

[0013] According to some embodiments, the predetermined threshold corresponds to a voltage difference greater than 1.5 V. Thus, the voltage drop is quantified as being greater than an appropriate value, and a fault signal is provided to the owner or user of the vehicle.

[0014] According to some embodiments, the method is performed periodically once a year. As the cables and their harnesses age, annual assessments of the vehicle's cables can provide information to the vehicle owner or user regarding electrical system safety issues.

[0015] According to some embodiments, execution of the method is associated with input that a maintenance interval reminder is about to occur. For example, if a maintenance light is activated, execution of the method is also initiated so that any problems with the electrical system can be brought to the attention of a maintenance technician when performing vehicle maintenance.

[0016] According to some embodiments, the method is performed each time the vehicle is started. Thus, any problem with the electrical system's cabling is detected as soon as the resistance difference is above a predetermined threshold.

[0017] According to a second aspect, a vehicle is provided comprising a power source, an electronic control unit, a cable and at least a first measurement point and a second measurement point along the cable, wherein the electronic control unit is arranged to perform the method according to the first aspect.

[0018] The effects and features of the second aspect are largely similar to those described above in conjunction with the first aspect. The embodiments mentioned in relation to the first aspect are largely compatible with the second aspect.

[0019] The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the present disclosure by way of illustration only. Those skilled in the art will appreciate from the guidance of the specific embodiments that changes and modifications may be made within the scope of the present disclosure.

[0020] Therefore, it should be understood that because such devices and methods can vary, the contents of this disclosure are not limited to the specific components of the devices described or the steps of the methods described. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limiting. It should be noted that, as used in the specification and the appended claims, the articles "a" and "the" are intended to indicate the presence of one or more elements, unless the context clearly indicates otherwise. Thus, for example, a reference to a "unit" or "the unit" may include several devices, etc. In addition, the words "comprises," "comprising," "containing," and similar expressions do not exclude other elements or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above-mentioned objects and other objects, features and advantages of the present disclosure will be more fully understood with reference to the following illustrative embodiments, which are described in detail in a non-limiting manner with reference to the accompanying drawings.

[0022] Figure 1 A vehicle according to an embodiment of the second aspect of the present disclosure is shown. Some components included in the vehicle are indicated by enlarged dotted circles.

[0023] Figure 2 A flow chart illustrating a method of an embodiment of the first aspect of the present disclosure is shown. DETAILED DESCRIPTION

[0024] The present disclosure will now be described with reference to the accompanying drawings, in which preferred exemplary embodiments of the present disclosure are shown. However, the present disclosure may be embodied in other forms and should not be construed as limited to the embodiments disclosed herein. The disclosed embodiments are provided to fully convey the scope of the present disclosure to those skilled in the art.

[0025] Figure 1 A vehicle 1 is shown, comprising a power source 2, an electronic control unit 3, a cable 4 and at least a first measurement point 5 and a second measurement point 6 along the cable. The electronic control unit 3 is arranged to use the measurement results from the first measurement point 5 and the second measurement point 6 to perform the method according to the present disclosure. Op The curved arrows in represent the current flowing from the power supply to the connected loads ECU1 to ECUn. The current is fed via cable 6, the aging of which is discussed herein.

[0026] refer to Figure 1 and Figure 2 A first aspect of the present disclosure shows a method for determining the resistance of a cable in a vehicle 1, comprising: S1: calculating the cable resistance based on the resistivity of the cable material, the cable length and the cable cross-sectional area; S2: calculating a corrected resistance value RT based on the theoretical temperature of the cable when a current flows through the cable; S3: measuring a real-time voltage drop between a first measuring point 5 and a second measuring point 6 along the cable and calculating the measured real-time resistance of the cable; S4: regularly comparing the measured real-time resistance with the corrected resistance value at predetermined time intervals; and S5: providing a fault signal if the difference is higher than a predetermined threshold.

[0027] The calculation formula of the cable resistance of the cable 4 is the resistivity of the cable material multiplied by the cable length divided by the cable cross-sectional area ρ*L / A[Ω]. When calculating the corrected resistance value RT, the calculation formula is R(T)=R Ref (1+α(T Op -T Ref )), where T Ref is the reference temperature, α is the temperature coefficient of resistance of the cable's conductor material, T Op is the operating temperature during conduction.

[0028] The fault signal is provided to the vehicle electronic control unit as a diagnostic fault code. In an embodiment of the present disclosure, the predetermined threshold corresponds to a voltage difference greater than 1.5V. The fault code can be displayed on any device in the vehicle (in Figure 1 In the embodiment of the present invention (indicated by ECU1 to ECUn in the figure), the device has communication means for communicating with the operator or owner of the vehicle. The fault code can be displayed on the dashboard display or in the infotainment system, for example, but it is also possible to transmit the fault code to the cloud or via a wireless telecommunication system.

[0029] Figure 2 The method disclosed in is preferably performed periodically (by Figure 2 (indicated by the arrow from S5 to S1 in FIG. 1 ). This method can be performed periodically, once a year; in conjunction with an input indicating an impending maintenance interval reminder; or whenever the vehicle is turned on. The more frequently the method is performed, the sooner it will be discovered if the cable has degraded below a safe level. However, since cable degradation is a relatively slow process, it may be sufficient to perform the method at longer intervals, such as once a year or when the vehicle reaches a maintenance interval.

[0030] Those skilled in the art will recognize that the present disclosure is not limited to the preferred embodiments described above. Those skilled in the art will also recognize that modifications and variations are possible within the scope of the appended claims. In addition, by studying the drawings, the disclosure, and the appended claims, those skilled in the art will understand and implement variations to the disclosed embodiments in practicing the claimed disclosure.

Claims

1. A method for determining the resistance of a cable in a vehicle (1), comprising: Calculating (S1) the cable resistance based on the resistivity of the cable material, the cable length and the cable cross-sectional area; calculating (S2) a corrected resistance value (R(T)) based on a theoretical temperature of the cable when current flows through the cable; measuring (S3) a real-time voltage drop between a first measuring point 5 and a second measuring point 6 along the cable, and calculating a measured real-time resistance of the cable; regularly comparing (S4) the measured real-time resistance with the calibrated resistance value at predetermined time intervals; as well as If the difference between the measured real-time resistance and the corrected resistance value is higher than a predetermined threshold, a fault signal is provided (S5).

2. The method according to claim 1, wherein The cable resistance is calculated as the resistivity of the cable material multiplied by the cable length divided by the cable cross-sectional area: (ρ*L / A[Ω]).

3. The method according to claim 1 or claim 2, wherein: The correction resistance value (R(T)) is calculated as: R(T)=R Ref (1+α(T Op -T Ref )), where T Ref is the reference temperature, α is the resistance temperature coefficient of the conductor material of the cable, T Op is the operating temperature during conduction.

4. A method according to any one of the preceding claims, wherein The fault signal is provided to the vehicle electronic control unit as a diagnostic trouble code.

5. The method according to claim 3, wherein The predetermined threshold corresponds to a voltage difference greater than 1.5V.

6. A method according to any one of the preceding claims, wherein The method is performed regularly once a year.

7. The method according to any one of claims 1 to 5, wherein The method is performed in association with input that a maintenance interval reminder is imminent.

8. The method according to any one of claims 1 to 5, wherein The method is performed each time the vehicle is turned on.

9. A vehicle (1) comprising a power source (2), an electronic control unit (3), a cable (4) and at least a first measurement point (5) and a second measurement point (6) along the cable, wherein: The electronic control unit (3) is configured to carry out a method according to any one of the preceding claims.

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