A method for modeling and simulation of wires

Abstract

A kind of wire modeling simulation method, it is first obtained that the core parameter of wire and insulating layer parameter, based on the basic component "wire" in Saber simulation software, wire core parameter and insulating layer parameter obtained are added in the basic component "wire" using MAST language, and the external temperature field parameter affecting the final temperature of wire is added, to establish wire model;By building simulation system, set different current and different temperature field, obtain the stable temperature and the current size of wire when reaching stable under different temperature field;According to the current of wire when reaching stable under different temperature field, obtain the current-temperature field relationship of wire corresponding to smoking temperature, form current-temperature field smoking curve under smoking temperature.The simulation result more consistent with actual heat generation of wire can be obtained by introducing wire thermal resistivity, thermal resistivity of insulating material, surface contact thermal resistance and temperature field, to provide more accurate basis for wire selection design.

Description

Technical Field

[0001] This invention belongs to the field of automotive wiring harness simulation technology, specifically relating to a wire modeling and simulation method. Background Technology

[0002] The design and matching of automotive wiring harness diameters is a crucial aspect of automotive wiring harness system development. The selection of wire diameter must consider both system safety and economy, based on the current carrying capacity and characteristics of the current. If the diameter is too small, prolonged high current flow will cause the wire to overheat, potentially reducing its current-carrying capacity and leading to melting if the temperature exceeds its rated capacity. Conversely, selecting a diameter that is too large increases cost and weight. Therefore, thorough design verification in the early stages to ensure appropriate wire selection is essential for both automotive economy and electrical safety.

[0003] Domestic and foreign scholars have achieved relatively mature results in the research on wire harness shape inspection and wire current carrying capacity test. Yuan Bingan et al. defined a defect evaluation standard to address the problem of appearance defects after wire harness terminal crimping, which solved the problem of low efficiency of manual inspection. Zhao Yang et al. simulated the typical extrusion load of high voltage wire harness under battery system collision conditions, which can accurately predict the short circuit risk under extrusion conditions. Li Jin et al. used COMSOL software to establish a finite element simulation model of vehicle wire electrothermal coupling, applied the Nelder-Mead method to calculate the vehicle wire current carrying capacity, and applied silicone rubber composite materials to improve the vehicle wire current carrying capacity.

[0004] However, there is little research on the establishment of conductor models and conductor simulation. At present, the simulation of circuit systems generally adopts the traditional analytical method, which ignores the influencing factors such as the thermal resistance and melting of conductors. This results in the actual system generating much more heat than the simulation result, especially for high-voltage conductors. Therefore, it is necessary to study new conductor modeling and simulation methods. Summary of the Invention

[0005] The purpose of this invention is to provide a method for modeling and simulating conductors, which can obtain simulation results that are more closely related to the actual heat generation of conductors by introducing the thermal resistivity of conductors, the thermal resistivity of insulating materials, the surface contact thermal resistance, and the temperature field.

[0006] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0007] A method for modeling and simulating conductors includes the following steps:

[0008] S1. Obtain conductor core parameters and insulation layer parameters: including conductor outer diameter, conductor inner diameter, conductor thermal resistance, number of cores, core material density, and insulation layer material density;

[0009] S2. Based on the basic component "wire" in the Saber simulation software, the core parameters and insulation layer parameters of the wire obtained in S1 are added to the basic component "wire" using the MAST language, and the external temperature field parameters that affect the final temperature of the wire are added to establish the wire model.

[0010] S3. A simulation system is built using a regulated power supply, the wire model established in S2, and an electronic load;

[0011] S4. In the simulation system built in S3, by setting different currents and different temperature fields, the stable temperature and current magnitude of the conductor when it reaches stability under different temperature fields are obtained.

[0012] S5. Select the smoke emission temperature of the conductor according to the conductor's temperature resistance rating. Based on the conductor current at stable conditions under different temperature fields obtained in S4, obtain the current-temperature field relationship of the conductor at the corresponding smoke emission temperature, and form the current-temperature field smoke emission curve at the smoke emission temperature.

[0013] Furthermore, in S1, the material of the inner core is copper.

[0014] Furthermore, in S2, based on Joule's law and the thermal balance between the wire and the environment, the core parameters, insulation parameters, and the magnitude of the external temperature field of the wire are added to the basic component "wire".

[0015] Furthermore, based on Joule's law, the formula for calculating the heat generated by a conductor is as follows:

[0016]

[0017] In the formula:

[0018] Q represents the heat generated by the wire;

[0019] I is the current in the conductor;

[0020] L is the length of the wire;

[0021] ρ is the resistivity of the conductor material;

[0022] α is the temperature coefficient of resistance;

[0023] Θ represents the conductor temperature;

[0024] S is the cross-sectional area of ​​the conductor;

[0025] Δt represents the heating time.

[0026] Furthermore, the formula for calculating the current in a conductor is as follows:

[0027]

[0028] In the formula:

[0029] I—current in the conductor;

[0030] r—resistance of the wire;

[0031] T1—Maximum operating temperature of the conductor;

[0032] T2—Ambient temperature;

[0033] R—Thermal resistance of the wire.

[0034] Furthermore, at temperature T1, the resistance r of the wire T1 The calculation formula is as follows:

[0035] r T1 =r0[1+0.00393(T1-T2)]

[0036] In the formula: r0—resistance of the wire at room temperature.

[0037] Furthermore, the thermal resistance R of the conductor is the sum of the thermal resistance R1 of the insulating material and the surface contact thermal resistance R2, i.e., R = R1 + R2.

[0038] The formula for calculating the thermal resistance R1 of the insulating material is as follows:

[0039]

[0040] In the formula:

[0041] P1—Thermal resistance of the insulating material;

[0042] d1—Outer diameter of the conductor;

[0043] d2—Insulation layer thickness;

[0044] The formula for calculating the surface contact thermal resistance R2 is as follows:

[0045]

[0046] In the formula:

[0047] d2—outer diameter of insulation; P2—contact thermal resistance of conductor surface. When d2≤12.5mm, P2=300+32d2; when d2≥12.5mm, P2=700.

[0048] Furthermore, in S4, the range of different currents is 5-280A, and the range of different temperature fields is 20-140℃.

[0049] Furthermore, the step size for different currents is 5A, and the step size for different temperature fields is 10℃.

[0050] Furthermore, the smoke emission temperature in S5 is 150°C.

[0051] Beneficial effects of this invention:

[0052] The simulation method of this invention, by introducing the thermal resistivity of the conductor, the thermal resistivity of the insulation material, the surface contact thermal resistance, and the temperature field, can obtain simulation results that are more closely related to the actual heat generation of the conductor. In the conductor selection and design stage, the current carrying capacity of the conductor can be simulated according to different current requirements and temperature resistance requirements, making the design more accurate. Attached Figure Description

[0053] Figure 1 Wiring diagram for the simulation system;

[0054] Figure 2 The relationship between temperature and current carrying capacity of conductors when the ambient temperature ranges from 20℃ to 140℃ is stable.

[0055] Figure 3 The maximum current carrying capacity (i.e., smoke emission curves) at different temperature fields when the smoke emission temperature is 150℃ is shown.

[0056] Figure 4 This is a comparison chart of the simulation results of the smoke emission curve of the conductor with the results obtained by the traditional analytical method and the smoke emission verification experiment. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. In the description of the present invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0058] Combination Figures 1 to 4 As shown, the present invention provides a method for modeling and simulating conductors, comprising the following steps:

[0059] S1. Obtain conductor core parameters and insulation layer parameters: including conductor outer diameter, conductor inner diameter, conductor thermal resistance. Specifically, it may also include the number of conductor cores, core material density, and insulation layer material density. For commonly used conductors, the core is usually made of copper wire. In this embodiment, a conductor with a copper wire core is selected. The parameters of the conductor are shown in Table 1.

[0060] Table 1. Parameters of the designed conductor

[0061]

[0062] S2. Based on the basic component "wire" in the Saber simulation software, the core parameters and insulation parameters of the wire obtained in S1 are added to the basic component "wire" using the MAST language, and external temperature field parameters that affect the final temperature of the wire are added to establish the wire model.

[0063] The original wire model in the Saber device library is a low-voltage wire model. In practice, it only has resistance and unit resistance parameter modules, and cannot reflect parameters such as voltage drop and temperature rise in actual electrical circuits. The original wire model was modified and parameters were added using the MAST language to set the wire temperature field, insulation material density, thermal resistance, and heat fusion parameters, as well as the core density, thermal resistance, and heat fusion parameters. A high-voltage wire model was established by using the relationship between the wire current carrying capacity calculation formula and the temperature rise.

[0064] The relationship between conductor current carrying capacity and temperature rise is as follows:

[0065] According to Joule's law and the law of thermal conduction, the flow of electric current through a conductor generates Joule heat, causing the conductor's temperature to rise. Thermal equilibrium is then achieved between the conductor and its surroundings through heat conduction. Specifically, a thermal equilibrium is formed between the heat generated by the conductor (Q), the heat consumed by the conductor's temperature rise (Q1), and the heat dissipated (Q2).

[0066] Assuming the conductor length is L, the cross-sectional area is S, the resistivity of the conductor material is ρ, the temperature coefficient of resistance is α, and the conductor temperature is Θ, according to Joule's law Q = I 2 r, heating time Δt, and the final heat generation of the conductor are given by formula (1).

[0067]

[0068] The current in the conductor is given by formula (2).

[0069]

[0070] In the formula:

[0071] I—current in the conductor;

[0072] r—resistance of the wire;

[0073] T1—Maximum operating temperature of the conductor;

[0074] T2—Ambient temperature;

[0075] R—Thermal resistance of the wire.

[0076] Furthermore, at temperature T1, the resistance of the wire The calculation formula is given by formula (3).

[0077] r T1=r0[1+0.00393(T1-T2)] (3)

[0078] In the formula:

[0079] T2—Ambient temperature;

[0080] r0 — Conductor resistance at room temperature.

[0081] In a wire circuit, the thermal resistance R of the wire is the sum of the thermal resistance R1 of the insulating material and the surface contact thermal resistance R2, that is, R = R1 + R2.

[0082] The formula for calculating the thermal resistance R1 of the insulating material is given by formula (4).

[0083]

[0084] In the formula:

[0085] P1—Thermal resistance of the insulating material;

[0086] d1—Outer diameter of the conductor;

[0087] d2—Insulation layer thickness.

[0088] The formula for calculating the surface contact thermal resistance R2 is given by formula (5).

[0089]

[0090] In the formula:

[0091] P2—Contact thermal resistance of the conductor surface. When d2≤12.5mm, P2=300+32d2; when d2≥12.5mm, P2=700.

[0092] S3. A simulation system is built using a regulated power supply, the wire model established in S2, and an electronic load. The system wiring diagram is as follows. Figure 1 As shown, in this embodiment, the voltage of the regulated source is set to 14V.

[0093] S4. In the simulation system built in S3, by setting different currents and temperature fields, the current magnitude of the conductor when it reaches its steady-state temperature under different temperature fields is obtained. Using the parameter scanning function in the Saber simulation software, the electronic load current and temperature field magnitude are scanned. The electronic load current range is set to 5A-280A with a step size of 5A, and the external temperature field magnitude is set to 20℃-140℃ with a step size of 10℃. By performing a parameterized scan, the current-carrying capacity (i.e., current magnitude) of the conductor when it reaches its steady-state temperature under different temperature fields can be obtained. The results are as follows: Figure 2 As shown.

[0094] S5. Select the smoke emission temperature of the conductor based on its temperature resistance rating. In this embodiment, the temperature resistance rating of the conductor under study is Class D, and its smoke emission temperature is 150℃. According to the relationship between the stable temperature and the conductor current under different temperature fields obtained in S4, where Y = 150 is set in the figure, that is, the smoke emission temperature of the conductor is set to 150℃, the initial temperature field magnitude when the conductor reaches the final stable temperature of 150℃ and the conductor current carrying capacity are taken out. The maximum current carrying capacity relationship of the conductor under different ambient temperatures can be obtained, that is, the smoke emission curve of the conductor. The simulation results of the conductor smoke emission curve are as follows. Figure 3 As shown.

[0095] Obtain the current-temperature field relationship of the conductor at the corresponding smoking temperature, form the current-temperature field smoking curve at the smoking temperature, and complete the modeling and simulation process of the conductor.

[0096] Verification experiment:

[0097] Based on the simulation results of the conductor model in this embodiment, the maximum current carrying capacity at a certain temperature can be calculated. A conductor smoke emission verification test is then conducted. The target test conductor for the verification test is 2 meters long and 25 mm in diameter. 2 The experimental equipment required for high-voltage conductors mainly includes programmable power supplies, electronic loads, vehicle electrical performance testing systems (cabinet type), constant temperature chambers, and batteries.

[0098] The experiment selected 13 sets of test temperatures, namely 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, and 140℃.

[0099] The steps for the conductor smoke emission verification test are as follows:

[0100] a) Connect temperature sensors at both ends and the middle section of the conductor, record the final stable temperature of the conductor, and take the average of the three points.

[0101] b) When the ambient temperature is 20°C, apply the rated current I0 to the conductor and record the temperature T1 and time t1 when the conductor temperature stabilizes.

[0102] c) Compare the measured steady-state temperature T1 of the conductor with the steady-state temperature T0 in the simulation results, adjust the current I0' applied to both ends of the conductor and continue the test until the steady-state temperature of the conductor can reach 150℃, and record the current I0' flowing through both ends of the conductor at this time.

[0103] d) Record I0', T1 and the experimental temperature of 20℃ to obtain the relationship between the actual measured ambient temperature and the overload current.

[0104] e) Repeat the above operation steps under temperature fields of 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, and 140℃, and plot the ambient temperature and overload current as a curve.

[0105] The comparison chart of verification experiment and simulation results with the results of traditional analytical methods is shown below. Figure 4 The results show that the accuracy of the smoke curve obtained by the traditional analytical method compared with the verification results is 90.5%, and the accuracy of the smoke curve obtained by the simulation results compared with the verification results is 93.11%. Compared with the results of the traditional analytical method, the simulation of the current carrying capacity of high voltage conductors based on Saber has a significant improvement in accuracy, which is optimized by 28.85%.

[0106] For high-voltage conductors (typically 600V AC / 1000V DC), the maximum current-carrying capacity of the conductor at the smoke emission temperature, as verified by experiments, is always higher than the current-carrying capacity of the conductor in simulations when the temperature is below 80℃. The opposite is true above 80℃, indicating that the actual current-carrying capacity of the conductor is stronger below 80℃. Generally, when selecting and designing conductors, the temperature field of the conductor is considered. Under normal circumstances, the temperature field inside the cabin of an electric vehicle is 20℃, and the temperature field in the front compartment is 80℃. Therefore, during the conductor design stage, the specifications of the conductors in the front compartment should be more stringent and cautious, while the specifications of the conductors in the cabin can be appropriately relaxed. After considering the composite factors such as the thermal resistivity of the conductor, the thermal resistivity of the insulation material, the surface contact thermal resistance, and the temperature field, the deviation curves between simulation and verification are not significantly different. Around 80℃, the selection can be relaxed or cautious depending on the appropriate situation.

[0107] It should be noted that the parts not described in detail in this article are prior art. The above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for modeling and simulating conductors, characterized in that, Includes the following steps: S1. Obtain conductor core parameters and insulation layer parameters: including conductor outer diameter, conductor inner diameter, conductor thermal resistance, number of cores, core material density, and insulation layer material density; S2. Based on the basic component "wire" in the Saber simulation software, the core parameters and insulation parameters of the wire obtained in S1 are added to the basic component "wire" using the MAST language, and the external temperature field parameters that affect the final temperature of the wire are added to establish the wire model. S3. A simulation system is built using a regulated power supply, the wire model established in S2, and an electronic load; S4. In the simulation system built in S3, by setting different currents and different temperature fields, the stable temperature and current magnitude of the conductor when it reaches stability under different temperature fields are obtained. S5. Select the smoke emission temperature of the conductor according to the conductor's temperature resistance rating. Based on the conductor current at stable conditions under different temperature fields obtained in S4, obtain the current-temperature field relationship of the conductor at the corresponding smoke emission temperature, and form the current-temperature field smoke emission curve at the smoke emission temperature.

2. The conductor modeling and simulation method as described in claim 1, characterized in that, In S1, the inner core is made of copper, and the insulation layer is made of XLPE cross-linked polyethylene.

3. The conductor modeling and simulation method as described in claim 1, characterized in that, In S2, based on Joule's law and the thermal balance between the wire and the environment, the core parameters, insulation parameters, and the magnitude of the external temperature field are added to the basic component "wire".

4. The conductor modeling and simulation method as described in claim 3, characterized in that, According to Joule's law, the formula for calculating the heat generated by a wire is as follows: In the formula: The heat generated by the conductor; The current in the conductor; The length of the wire; The resistivity of the conductor material; It is the temperature coefficient of resistance; For the temperature of the conductor; Cross-sectional area of ​​the conductor Δt represents the heating time.

5. The conductor modeling and simulation method as described in claim 4, characterized in that, The formula for calculating conductor current is as follows: In the formula: - Current in the conductor; - Resistance of the wire; - Maximum operating temperature of the conductor; -Ambient temperature; - Thermal resistance of the wire.

6. The conductor modeling and simulation method as described in claim 5, characterized in that, Temperature is When, the resistance of the wire The calculation formula is as follows: In the formula: - Resistance of a wire at room temperature.

7. The conductor modeling and simulation method as described in claim 5, characterized in that, The thermal resistance R of the conductor is the thermal resistance of the insulating material. Surface contact thermal resistance The sum, that is , Among them, the thermal resistance of insulating materials The calculation formula is as follows: In the formula: -Specific thermal resistance of insulating materials; -Outer diameter of the conductor; - Insulation layer thickness; Surface contact thermal resistance The calculation formula is as follows: In the formula: - Insulation layer thickness; -The surface of the conductor contacts a specific thermal resistance, when hour, ,when hour, .

8. The conductor modeling and simulation method as described in claim 1, characterized in that, In S4, the range of different currents is 5-280A, and the range of different temperature fields is 20-140℃.

9. The conductor modeling and simulation method as described in claim 4, characterized in that, The step size for different currents is 5A, and the step size for different temperature fields is 10℃.

10. The conductor modeling and simulation method as described in claim 1, characterized in that, The smoke emission temperature in S5 is 150℃.

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