Automobile wire harness overload dynamic protection method

Abstract

The present application belongs to the field of low-voltage electrical technology of vehicles, and particularly relates to a kind of automobile wire harness overload dynamic protection methods.Through the real-time current of vehicle load is obtained after the vehicle load is powered on, and when the real-time current is greater than the set multiple of the steady-state current of the vehicle load, and the duration exceeds the set multiple of the impact current duration of the vehicle load, the vehicle load circuit is cut off.Through the real-time current of vehicle load end is obtained in real time after the vehicle load is powered on, and when the real-time current is greater than the overcurrent threshold (i.e.the set multiple of the steady-state current of the vehicle load) within the set time threshold (i.e.the set multiple of the impact current duration of the vehicle load), the load circuit is cut off, and the duration is also used as a basis for determining whether the current is abnormal, which can avoid the situation that the normal impact current is determined as abnormal current when there is a capacitive or inductive load at the load end, and further avoid the problem of frequent false protection after the vehicle load is powered on.

Description

Technical Field

[0001] This invention belongs to the field of vehicle low-voltage electrical technology, specifically relating to a dynamic overload protection method for automotive wiring harnesses. Background Technology

[0002] There are two common types of low-voltage overcurrent protection for existing buses. One is to match a fuse of appropriate specifications; the other is to use a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) to achieve overload protection by configuring a protection threshold. Both of these protection methods involve setting a protection threshold in advance and then using dynamic current detection to determine whether the current exceeds the protection threshold. If the protection threshold is exceeded, the overcurrent protection is activated; otherwise, the overcurrent protection is not activated.

[0003] Fuse is currently the most widely used method for circuit overload protection. However, its inherent characteristics make it impossible to achieve precise matching, resulting in poor practical application performance and significant safety hazards. For example, when facing overcurrents of 110% to 135%, its protection time is affected by the number of times the fuse is energized and the ambient temperature. At 110% overcurrent, the protection time can be as long as 400 hours, which is almost negligible. At 135% overcurrent, the maximum protection time is 90 seconds. The protection action time in this case is too long. Furthermore, since the heat generation of the wiring harness is exponentially related to the current, the heat generated during overload is enormous. In addition, the heat dissipation conditions of vehicle wiring harnesses are poor, which can easily lead to wiring harness burnout or vehicle fire.

[0004] Existing protection methods that use MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) to preset current protection thresholds can improve protection speed to the millisecond level compared to fuses. However, when dealing with capacitive and inductive loads, the starting current of such electrical loads is usually 3 to 5 times the normal operating current. The MOSFET protection circuit cannot currently distinguish between short-circuit current and inrush current, resulting in frequent false protection failures when the circuit is powered on, causing the load circuit to fail to start normally. Summary of the Invention

[0005] The purpose of this invention is to provide a dynamic overload protection method for automotive wiring harnesses, which solves the problem of frequent false protection when power is applied in existing MOSFE-based protection methods because they cannot identify short-circuit current and inrush current.

[0006] To solve the above-mentioned technical problems, the present invention provides a dynamic overload protection method for automotive wiring harnesses, comprising the following steps:

[0007] 1) After the vehicle load is powered on, obtain the real-time current of the vehicle load;

[0008] 2) When the real-time current is greater than the set multiple of the steady-state current of the vehicle load, and the duration exceeds the set multiple of the duration of the impact current of the vehicle load, disconnect the vehicle load circuit.

[0009] Its beneficial effects are as follows: by acquiring the real-time current at the vehicle load end after the vehicle load is powered on, and only cutting off the load circuit when the real-time current exceeds the overcurrent threshold (i.e., the vehicle load steady-state current set multiple) for a period of time that is continuously within a set time threshold (i.e., within a period of time that is a set multiple of the duration of the vehicle load inrush current), the duration is also used as a basis for judging whether the current is abnormal. This can avoid the situation where a normal inrush current is judged as an abnormal current when there is a capacitive or inductive load at the load end, thereby avoiding the problem of frequent false protection after the vehicle load is powered on.

[0010] Furthermore, in step 2), a case where the real-time current is greater than the set multiple of the steady-state current of the vehicle load but less than the set multiple of the impact current of the vehicle load is judged as an overcurrent fault, and a case where the real-time current is greater than the set multiple of the impact current of the vehicle load is judged as a short-circuit fault.

[0011] Because the degree of current anomaly differs between overcurrent faults and short-circuit faults, by adding a criterion of impulse current threshold (i.e., a set multiple of the load impulse current), a short-circuit fault can be identified when the real-time current exceeds the impulse current threshold and lasts for more than a set time threshold. Conversely, an overcurrent fault can be identified when the real-time current does not exceed the impulse current threshold but exceeds the overcurrent threshold and lasts for more than a set time threshold. In other words, by adding an impulse current threshold criterion, the current anomaly can be further subdivided, thereby improving the reliability of the judgment results.

[0012] Furthermore, when the real-time current is less than the set open-circuit protection multiple of the vehicle load steady-state current, and the duration exceeds the set multiple of the duration of the vehicle load inrush current, the corresponding load circuit is determined to be in an open-circuit state.

[0013] The open-circuit current threshold (i.e., the vehicle load steady-state current setting open-circuit protection multiple) is used as the basis for judging whether the vehicle load has an open-circuit abnormal condition. By increasing the duration of exceeding the set time threshold, the normal current of the vehicle load is avoided due to accidental situations, thus making the judgment result more accurate.

[0014] Furthermore, the steady-state current of the load is obtained by performing median value filtering on several current data points of the same vehicle model under normal working conditions.

[0015] By filtering the vehicle load current data under previous vehicle operating conditions based on the median value, the fluctuation interference caused by accidental factors can be overcome. Therefore, the obtained current data can accurately reflect the steady-state current of the vehicle load under vehicle operating conditions. The process of obtaining the overcurrent threshold value based on this steady-state current and comparing this overcurrent threshold value with the real-time current data of the vehicle can accurately reflect the current change at the vehicle load end, and thus identify the abnormal or normal current state of the vehicle load.

[0016] Furthermore, the median value filtering process is performed on several impact current duration data of the corresponding load of the same vehicle model when it was previously energized to obtain the impact current duration of the vehicle load.

[0017] By using previous vehicle load surge current duration data and filtering it based on the median value, fluctuations caused by accidental factors can be overcome, thus obtaining a more accurate vehicle load surge current duration.

[0018] Furthermore, the impact current of the vehicle load is obtained by performing median filtering on several impact current data points from previous energizations of the load corresponding to the same vehicle model; the impact current data is: M times the steady-state current of the load, and the duration is less than the duration of the impact current; the value of M is 3 to 7.

[0019] By performing median filtering on the previous inrush current data of the corresponding vehicle, the median-filtered data overcomes the fluctuation interference caused by accidental factors. Therefore, the inrush current threshold value obtained after median filtering can accurately reflect the inrush current value of the vehicle load. Furthermore, by comparing this inrush current value with the real-time current data acquired by the vehicle, the current change at the vehicle load end can be accurately reflected. Since the current during a load short circuit is larger than this inrush current value, the magnitude and duration of this inrush current value can accurately determine whether there is a short circuit abnormality in the vehicle load.

[0020] Furthermore, the set multiple is 1.2 to 3.

[0021] Furthermore, the value of the set open-circuit protection multiple is 0.2 to 0.5.

[0022] Furthermore, after the vehicle load is powered on, the current is compared horizontally with that of the same load on the same vehicle. If the current is greater than the average current of the same load on the same vehicle and the duration exceeds the duration of the impact current of the vehicle load, the vehicle load is judged to be overloaded.

[0023] The system not only compares the vehicle's real-time current with its own current threshold, but also compares the real-time current of the vehicle's load with that of other vehicle loads of the same type. This allows the system to identify the difference between the real-time current of this vehicle load and that of other vehicles. If the difference is too large, it indicates that there is a problem with the vehicle load. An abnormal situation is only confirmed when the difference persists for a set time threshold. This avoids misjudgments caused by random factors. Since the current data of vehicle loads of the same type should be relatively stable, if there is a large difference in current data, the vehicle load with the large difference has a problem. Therefore, based on this process, vehicle load faults can be accurately predicted.

[0024] Furthermore, after the vehicle load is powered on, the current is compared horizontally with that of the same load in the same vehicle. If the current is less than the average current of the same load in the same vehicle and the open circuit protection multiple is set, and the duration exceeds the duration of the inrush current of the vehicle load, the vehicle load is determined to be open circuit.

[0025] Because by comparing the real-time current with that of the vehicle, there are two possibilities: the real-time current of the vehicle is too high or too low. Therefore, there are two abnormal states based on these two situations: when the current is too high, there is an overload state; when the current is too low, there is an open circuit state. Therefore, by comparing the real-time current of the vehicle with the real-time overload current threshold and the real-time open circuit current threshold (the average current of the same vehicle with the same load is set as the open circuit protection multiple), the fault type of the vehicle can be accurately determined. Furthermore, the judgment based on the duration avoids misjudgment caused by differences due to random factors, thereby improving the reliability of the judgment result. Attached Figure Description

[0026] Figure 1 This is a schematic diagram showing the relationship between the average impact current and the steady-state load current and the duration of the impact current in this invention;

[0027] Figure 2 This is a flowchart of the single vehicle overload judgment process of the present invention;

[0028] Figure 3 This is a schematic diagram showing the real-time current summary and comparison of the same type of load in different vehicles of the same model according to the present invention.

[0029] Figure 4 This is a schematic diagram of the system for implementing the dynamic overload protection method for automotive wiring harnesses according to the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] Example of a dynamic overload protection method for automotive wiring harnesses:

[0032] This embodiment compares the real-time current of the vehicle load with the overcurrent threshold and adds a duration criterion. That is, the vehicle load is judged as having an abnormal current only when the real-time current exceeds the overcurrent threshold and the duration also exceeds the set time threshold. The set time threshold is set based on the duration of the inrush current. This set time threshold is to avoid misjudging the normal inrush current when there is inductance or current at the vehicle load end as an abnormal current. Therefore, by judging the vehicle load as having an abnormal current only when the real-time current exceeds the overcurrent threshold and the duration also exceeds the set time threshold, false protection is avoided, which is conducive to the normal start-up of the vehicle load.

[0033] The specific process of the automotive wiring harness overload dynamic protection method in this embodiment is as follows:

[0034] like Figure 4 The diagram illustrates the system for implementing the dynamic overload protection method for automotive wiring harnesses in this embodiment. Each vehicle includes a current detection unit, an execution unit, and a control unit. The current detection unit periodically collects device current data after the vehicle load is energized to obtain real-time current data of the vehicle load (in this embodiment, the real-time current flowing through the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is detected using a sampling period of T1). The control unit collects the real-time current data obtained by the current detection unit, receives signal commands, and issues control commands to the execution unit. The execution unit, i.e., power devices such as MOSFETs, primarily executes the commands issued by the control unit to switch the power supply on and off the load line. In this embodiment, when the execution unit receives an open command from the control unit, it performs a closing operation, energizing the load device. When the execution unit receives a close command from the control unit, it performs a disconnect operation, de-energizing the load device. Furthermore, the control unit of each vehicle is also communicatively connected to a cloud data analysis unit to send the real-time current data of the vehicle load to the cloud data analysis unit. The cloud data analysis unit processes the received real-time current data and feeds back the processing results to the control unit.

[0035] The cloud data analysis unit in this embodiment can obtain the steady-state current I of the vehicle load. Normal Average impact current I Peak Duration of the impact current T Peak And the average load current I of the same type of load in different vehicles of the same model avg .

[0036] Among them I NormalThe acquisition process is as follows: The median value filtering is performed on the most recent N current sampling data (which are the current sampling data when the load is operating normally) acquired from the corresponding load of the same vehicle (or, in other real-time methods, the corresponding load of the same vehicle model) to obtain the steady-state load current I of this vehicle. Normal I Peak And T Peak The acquisition process is as follows: After performing median filtering on the most recent N impact current sampling data of the same vehicle, the average impact current I of this vehicle is obtained. Peak The median value filtering process was performed on the N impact current duration sampling data to obtain the impact current duration T of this vehicle. Peak The relationship between the average impulse current and the steady-state load current and the duration of the impulse current is as follows: Figure 1 As shown, in this embodiment, a load steady-state current I is defined as greater than M times (based on experimental data, M ranges from 3 to 7). Normal Furthermore, sampling currents with a duration of less than X ms (based on experimental data, X ranges from 10 to 100) are considered impulse currents. avg The acquisition process is as follows: the steady-state current of the same type of load in different vehicles of the same model is averaged to obtain the average load current I. avg Because of the load steady-state current I Normal Based on median filtering, it can overcome fluctuations caused by accidental factors, thus obtaining current data that accurately reflects the steady-state current of the vehicle load under vehicle operating conditions. This data is then used to determine the steady-state load current I. Normal The obtained I Peak And T Peak The data is more accurate and is based on the load steady-state current I. Normal It is obtained by acquiring the most recent N impulse current sampling data and processing them accordingly, so the load steady-state current I Normal It reflects the current value as close to the real-time state and can be dynamically changed.

[0037] I obtained from cloud data analysis unit Normal I Peak And T Peak The data is transmitted to the control unit of the corresponding vehicle, enabling local protection for a single vehicle. First, the control unit defines an overload protection sensitivity coefficient K (based on experimental data, K ranges from 1.2 to 3), which adjusts the overload protection sensitivity by changing the K value. The control unit also defines an open-circuit protection sensitivity coefficient L (based on experimental data, L ranges from 0.2 to 0.5), which adjusts the open-circuit protection sensitivity by changing the L value.

[0038] By defining the protection sensitivity coefficient, it is possible to achieve, for example Figure 2 The control process shown:

[0039] 1) After the vehicle load is powered on, obtain the real-time current I of the vehicle load. real ;

[0040] 2) Determine the load circuit status (i.e., the equipment status of the vehicle load) based on the real-time current; the load circuit status includes open circuit status, short circuit status, overcurrent status, and normal status.

[0041] 3) When K*I Normal <I real <K*I Peak And T dely >K*T Peak T dely To satisfy K*I Normal <I real <K*I Peak The real-time current duration (i.e., abnormal current duration) is determined to be an overcurrent state if the real-time current exceeds the dynamic overcurrent threshold and the duration exceeds the inrush current duration (i.e., the set time threshold).

[0042] When K*I Peak <I real And T dely >K*T Peak T dely To satisfy K*I Peak <I real The real-time current duration (i.e., the abnormal current duration) means that if the real-time current exceeds the dynamic impact current threshold and the duration exceeds the impact current duration, the load circuit is judged to be in a short-circuit state.

[0043] When L*I Normal >I real And T dely >K*T Peak T dely To satisfy L*I Normal >I real The real-time current duration (i.e., the abnormal current duration) is determined to be an open circuit state if the real-time current is less than the dynamic open circuit current threshold and the duration exceeds the impact current time.

[0044] If none of the above three conditions are met, the load circuit is judged to be in a normal state.

[0045] 4) When the load circuit is determined to be in an overcurrent state, short circuit state, or open circuit state, the protection is activated. That is, the control unit sends a command to the execution unit to disconnect the MOSFET, and then the execution unit executes the corresponding command to shut down the load circuit. When the load circuit is determined to be in a normal state, no action is taken, and the load can operate normally.

[0046] By acquiring the real-time current at the vehicle load end after the vehicle load is powered on, and only when the real-time current exceeds the overcurrent threshold for a set time threshold period, is the current considered abnormal. This approach, by including duration as a criterion for current abnormality, avoids misclassifying normal inrush current as abnormal current when capacitive or inductive loads are present, thus preventing frequent false protection issues after the vehicle load is powered on. Furthermore, because the degree of current abnormality differs between load short circuits and load overcurrents, adding an inrush current threshold criterion allows for the determination of a load short circuit (i.e., short circuit abnormality) when the real-time current exceeds the inrush current threshold for a duration exceeding the set time threshold, and an overcurrent (i.e., overcurrent abnormality) when the real-time current does not exceed the inrush current threshold but exceeds the overcurrent threshold for a duration exceeding the set time threshold. By adding an inrush current threshold criterion, current abnormalities can be further subdivided, thereby improving the reliability of the judgment results.

[0047] I obtained from cloud data analysis unit avg In addition to local current protection for individual vehicles, cloud-based data analysis can also provide early warnings of the following circuit faults:

[0048] When K*I avg <I real And T dely >K*T Peak That is, when comparing the real-time current of a single vehicle in a horizontal manner, it is significantly greater than that of other vehicles (such as...). Figure 3 In vehicle 3), if the load current of the vehicle is determined to be overloaded, the abnormal information should be promptly transmitted to the faulty vehicle, and an alarm message should be displayed on the instrument panel to inform the driver of the vehicle fault information; when L*I avg >I real And T dely >K*T Peak That is, when comparing the real-time current of a single vehicle laterally, it is significantly smaller than that of other vehicles (such as...). Figure 3If vehicle 13 is found to have an open circuit in its load circuit, the abnormal information should be promptly transmitted to the faulty vehicle, and an alarm message should be displayed on the instrument panel to inform the driver of the vehicle fault information. Because comparing the real-time current with that of the vehicle reveals two possibilities—either the real-time current is too high or too low—there are two abnormal states: an overload state when the current is too high, and an open circuit state when the current is too low. Therefore, comparing the vehicle's real-time current with the real-time overload current threshold and the real-time open circuit current threshold allows for accurate determination of the vehicle's fault type. Furthermore, the time-based judgment avoids misjudgments caused by random factors, thus improving the reliability of the judgment results.

[0049] The system not only compares the vehicle's own real-time current with its own current threshold, but also compares the real-time current of the vehicle's load with that of other vehicle loads of the same type. It identifies the difference between the real-time current of this vehicle load and other vehicles, and determines that the vehicle load has a problem when the difference exceeds a threshold. An abnormal situation is only confirmed after the difference exceeds the threshold for a set period, and then an early warning is issued. This avoids misjudgments caused by random differences. Since the current data of vehicle loads of the same type should be relatively stable, if there is a large difference in current data, the vehicle load with the large difference has a problem. Therefore, based on this process, vehicle load faults can be accurately predicted, and accurate early warning information can be issued to the vehicle.

[0050] This invention provides a protection method that can dynamically correct overload protection parameters based on different load characteristics. While ensuring the timeliness and accuracy of overcurrent protection, this method can also accurately identify short-circuit current and inrush current, avoiding false protection caused by the starting characteristics of different electrical equipment and inrush current during operation. At the same time, with the help of the powerful computing power of the cloud data analysis unit, the load current change trend can be tracked in real time, and load equipment with abnormal working status can be identified in a timely manner.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A method for dynamic overload protection of automotive wiring harnesses, characterized in that, Includes the following steps: 1) After the vehicle load is powered on, obtain the real-time current of the vehicle load; 2) When the real-time current is greater than the set multiple of the steady-state current of the vehicle load and less than the set multiple of the inrush current of the vehicle load, and the duration of the real-time current exceeds the set multiple of the duration of the inrush current of the vehicle load, the corresponding load circuit is judged to be an overcurrent fault. When the real-time current is greater than the set multiple of the vehicle load impact current, and the duration of the real-time current exceeds the set multiple of the duration of the vehicle load impact current, the corresponding load circuit is judged to be short-circuit fault. When the real-time current is less than the set open-circuit protection multiple of the steady-state current of the vehicle load, and the duration of the real-time current exceeds the set multiple of the duration of the inrush current of the vehicle load, the corresponding load circuit is determined to be in an open-circuit state. The vehicle load inrush current and the duration of the vehicle load inrush current are obtained by median filtering of several current data points when the vehicle of the same model is operating normally under the corresponding load. 3) If the corresponding load circuit is in an overcurrent fault, short circuit fault or open circuit state, disconnect the vehicle load circuit.

2. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, If the corresponding load circuit is not in an overcurrent fault, short circuit fault, or open circuit state, then the corresponding load circuit is determined to be in a normal state and no action is taken.

3. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, The vehicle load inrush current and the duration of the vehicle load inrush current were obtained by analysis using a cloud data analysis unit.

4. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, The steady-state current of the load is obtained by performing median value filtering on several current data points of the same vehicle model under normal load conditions.

5. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, The duration of the vehicle load impact current is between 10 and 100 ms.

6. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, The vehicle load inrush current data is: M times the steady-state current of the load, and the duration is less than the duration of the vehicle load inrush current, where M is 3 to 7.

7. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, The set multiple of the vehicle load impact current is 1.2 to 3.

8. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, The value of the set open circuit protection multiple is 0.2 to 0.

5.

9. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, After the vehicle load is powered on, the real-time current is compared horizontally with the same load of the same model vehicle. When the real-time current is greater than the average current of the same load of the same model vehicle by a set multiple, and the duration exceeds the set multiple of the duration of the load surge current of the vehicle, the vehicle load is judged to have a short circuit fault.

10. The automotive wiring harness overload dynamic protection method according to claim 1, characterized in that, After the vehicle load is powered on, the real-time current is compared horizontally with the same load of the same model vehicle. When the real-time current is less than the average current of the same load of the same model vehicle set open circuit protection multiple, and the duration exceeds the set multiple of the inrush current duration of the vehicle load, the vehicle load is determined to be in an open circuit state.

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