CN-121997666-A - New energy automobile high-voltage wire harness shielding and noise reduction method

CN121997666ACN 121997666 ACN121997666 ACN 121997666ACN-121997666-A

Abstract

The invention discloses a shielding and noise reduction method for a high-voltage wire harness of a new energy automobile, which relates to the technical field of computer aided engineering and comprises the following steps of adopting three-dimensional full-wave electromagnetic simulation to identify noise source frequency characteristics and coupling paths and establishing an electromagnetic interference model; the method comprises the steps of designing a composite shielding structure and core parameters, matching an insulating buffer layer and a flame-retardant protective layer, optimizing parameter combination through electromagnetic simulation, designing a grounding scheme according to the characteristics of a wire harness to form a low-impedance loop, optimizing the trend and fixing mode of the wire harness, controlling the distance between the wire harnesses, connecting the shielding layer and a grounding terminal through an ultrasonic welding process, and forming a standardized process specification through multi-process test. According to the invention, through simulation optimization, structural design, process compensation and full-flow verification, the shielding accuracy and environmental adaptability are improved, the stability under vibration and aging working conditions is enhanced, the shielding defect is overcome, the electromagnetic compatibility of the whole vehicle is ensured, and the problems of rough design and insufficient reliability of the existing method are solved.

Inventors

ZHU XIAOGANG
WANG LIFU
WANG HUI
WANG YONGZHAO
LI CONG

Assignees

常州中电新能电器科技有限公司

Dates

Publication Date: 20260508
Application Date: 20260128

Claims (10)

1. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile is characterized by comprising the following steps of: Scanning the high-voltage wire harness operation environment of the new energy automobile by adopting a three-dimensional full-wave electromagnetic simulation technology, identifying the characteristics of a key noise source, completing time domain-frequency domain conversion through Fourier transformation, analyzing the type of an interference coupling path, quantifying the electromagnetic coupling strength of the wire harness and peripheral electronic components, and establishing an electromagnetic interference mathematical model; The parameterized design step of the shielding structure comprises the steps of determining core parameters of the shielding layer based on an electromagnetic interference model, selecting an adaptive shielding structure according to an interference frequency range, arranging a polytetrafluoroethylene insulating buffer layer on the inner side of the shielding layer, and wrapping a flame-retardant polyolefin protective layer on the outer side of the shielding layer; The electromagnetic simulation optimizing step is that a three-dimensional simulation model of the high-voltage wire harness shielding system is built by utilizing finite element electromagnetic simulation software, noise excitation parameters under different working conditions are input, attenuation characteristics of the shielding layer to interference of different frequency segments are simulated, mapping relation between the shielding layer parameters and shielding effectiveness is analyzed, parameter combination is adjusted, and attenuation effects are stabilized; The shielding layer and the grounding collaborative design step, namely selecting an adaptive grounding scheme according to the length of the wire harness and the interference frequency characteristic, optimizing the grounding position and the sectional area of a conductor to form a low-impedance loop, verifying the suppression characteristic of the grounding scheme on common-mode interference, and reducing the shielding failure probability; planning a high-voltage wire harness trend path, bypassing a strong interference source region, controlling the distance between the wire harness and a sensitive electronic component, installing the wire harness by adopting a vibration-proof fixed buckle, reserving a bending buffer section, and reducing the abrasion of a shielding layer and the contact impedance change; And the process implementation and performance test steps are that a shielding structure is processed according to optimized parameters, an ultrasonic welding process is adopted to connect a shielding layer and a grounding terminal, shielding effectiveness and noise reduction performance under complex working conditions are detected, and a standardized shielding noise reduction process specification is formed.
2. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile according to claim 1, further comprising a multi-field coupling simulation optimization step, wherein electromagnetic simulation, temperature field simulation and mechanical field simulation are combined, the influence of heating effect of the high-voltage wire harness in operation on the conductive performance of the shielding layer material is analyzed, the temperature distribution and the conductivity change rate of the shielding layer are monitored, and meanwhile the deformation rule and the contact state change of the shielding layer braided structure under the vibration working condition are simulated.
3. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile according to claim 1, further comprising a shielding layer defect compensation step, wherein defects of the shielding layer are detected by adopting an eddy current flaw detection technology, defect positions, sizes and morphological parameters are recorded, a shielding effectiveness attenuation compensation model is built based on defect data, and defect influences are compensated by adopting a mode of locally thickening the shielding layer, adding an auxiliary shielding net or optimizing a grounding path for different defect types.
4. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile according to claim 1, wherein in the electromagnetic simulation optimization step, a shielding effectiveness accurate calculation formula is constructed Wherein In order to achieve a shielding effectiveness, the shielding effectiveness, For the intensity of the incident electric field, In order to transmit the intensity of the electric field, Is the electrical conductivity of the material, and the material, For the thickness of the shielding layer, In order to shield the resistivity of the material, In order to interfere with the signal frequency, As a result of the structural coupling coefficient, In order to provide a braid density for the shield, Is the wire harness diameter.
5. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile according to claim 1 is characterized in that in the step of collaborative design of the shielding layer and the grounding, a dynamic grounding resistance optimization strategy is adopted, the length and the sectional area of a grounding conductor are dynamically adjusted according to the working current amplitude and the interference frequency of the high-voltage wire harness, the grounding impedance is reduced through a parallel high-frequency grounding capacitor in a key interference frequency section, the grounding capacitance value is selected according to the interference frequency characteristic, and the suppression effect of different grounding schemes on common mode interference is verified by utilizing electromagnetic simulation.
6. The method for shielding and noise reduction of high-voltage wire harnesses of a new energy automobile according to claim 1, wherein in the wire harness arrangement and fixing optimization step, a wire harness spacing electromagnetic interference attenuation type is constructed Wherein In order to achieve the amount of interference attenuation, As the attenuation coefficient of the medium, Is the central axis spacing of the wire harness, For the safety spacing threshold value, As a length-wise attenuation coefficient, For the parallel arrangement length of the wire harness, Is the interference signal frequency.
7. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile according to claim 1, further comprising a vibration self-adaptive shielding and strengthening step, wherein vibration frequency and amplitude data in the running process of the new energy automobile are obtained through a whole automobile road spectrum test, elastic shielding joints made of silicone rubber are adopted at the vibration parts of an engine cabin and a chassis of the high-voltage wire harness, a corrugated buffer connection structure between a shielding layer and a wire harness core wire is designed, and the distance and clamping force parameters of a fixed buckle are optimized through mechanical simulation.
8. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile according to claim 1, wherein in the process implementation step, welding process parameter compensation type is constructed Wherein In order to optimize the welding parameters, As a reference welding parameter, the welding parameters, For the temperature compensation coefficient to be a function of the temperature, As the difference between the actual temperature and the standard temperature, Is the standard welding temperature, the temperature of the welding machine is the standard welding temperature, For the compensation coefficient of the resistance, To provide a difference between the actual resistance of the shield and the standard resistance, And the welding parameters are dynamically adjusted by monitoring the temperature of a welding area and the resistance change of the shielding layer in real time every second for the standard resistance of the shielding layer, so that the connection conductivity of the shielding layer and the grounding terminal is ensured.
9. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile according to claim 1, further comprising an aging and reliability verification step, wherein the processed high-voltage wire harness is placed in a high-low temperature circulation environment of-40 ℃ to 85 ℃, a humidity and heat aging environment of 40 ℃ to 95% RH and a salt spray corrosion environment of 5% NaCl, test conditions of 50 times of high-low temperature circulation, humidity and heat aging for 1000 hours and salt spray corrosion for 500 hours are set, shielding effectiveness changes in different aging stages are continuously monitored, the service life of a shielding system is predicted through fitting accelerated aging test data, and a shielding layer material formula and technological parameters are optimized for performance attenuation problems in an aging process.
10. The shielding and noise reduction method for the high-voltage wire harness of the new energy automobile according to claim 1, further comprising a whole automobile integrated verification step, wherein the optimized high-voltage wire harness is installed on a real automobile, an electromagnetic compatibility test of the whole automobile is carried out according to GB/T18387-2017 electromagnetic field radiation intensity limit value and measurement method of electric automobile, interference levels of the wire harness on an on-board radar, navigation and communication system under different driving conditions are detected, and the electromagnetic compatibility problem found in the test is solved by adjusting the wire harness arrangement path, the grounding position or the shielding layer parameters, so that a high-voltage wire harness shielding and noise reduction implementation scheme suitable for a specific automobile type is formed.

Description

New energy automobile high-voltage wire harness shielding and noise reduction method Technical Field The invention relates to the technical field of computer-aided engineering, in particular to a shielding and noise reduction method for a high-voltage wire harness of a new energy automobile. Background The rapid development of new energy automobiles promotes the wide application of high-voltage electric systems, the high-voltage wire bundles are used as energy transmission carriers of core components such as power batteries, motor controllers, inverters and the like, the working voltage of the high-voltage wire bundles can reach hundreds of volts, the working current of the high-voltage wire bundles reaches hundreds of amperes, and strong electromagnetic interference is easy to generate in the running process. The electromagnetic interference not only can influence the normal operation of sensitive electronic equipment such as vehicle radar, navigation and communication systems, and the like, so that signal distortion and functional failure are caused, but also can interfere the stable operation of a whole vehicle control system, and potential safety hazards are caused. Meanwhile, the new energy automobile has compact internal space, small arrangement space between the high-voltage wire harness and various electronic components and complex electromagnetic coupling path, further aggravates the problem of electromagnetic interference and becomes a key bottleneck for restricting the improvement of the electromagnetic compatibility of the new energy automobile. The shielding and noise reduction method of the existing high-voltage wire harness of the new energy automobile has various limitations. In the design stage, most methods rely on engineering experience to select shielding structures and parameters, lack of accurate optimization based on electromagnetic simulation, and the parameters such as shielding layer material selection, thickness, weaving density and the like are not matched with actual interference characteristics, so that insufficient shielding efficiency or excessive design is caused, and cost waste is caused. Although electromagnetic simulation is introduced in part of the method, only electromagnetic field factors are considered singly, heating effect during high-voltage wire harness working and vibration influence during vehicle running are ignored, the conductive performance of the shielding layer material is attenuated under temperature change, deformation and abrasion of the woven structure are easy to occur in vibration, and the actual shielding performance and design expectation deviation are large. The design of the grounding system and the cooperation of the shielding layer are not enough, the grounding scheme is single, the grounding scheme cannot be dynamically adjusted according to the interference frequency and the length of the wire harness, the shielding failure is caused by the excessively high grounding impedance, and the common-mode interference suppression effect is poor. The prior method lacks quantitative space design basis on the aspects of wire harness arrangement and process implementation, the arrangement of high-voltage wire harnesses and sensitive parts is controlled by experience, the parallel arrangement length is too long, coupling interference is easy to be aggravated, the design of fixed buckle space and clamping force is unreasonable, and vibration during vehicle running causes poor contact between a shielding layer and a grounding terminal and abrasion and damage of the shielding layer, so that an electromagnetic leakage point is formed. The welding process parameters are fixed, the influences of temperature and resistance change of the shielding layer are not considered, the contact resistance of the connecting part is overlarge, and the shielding effect is further weakened. In addition, the existing method lacks perfect defect compensation, ageing verification and whole vehicle integrated verification processes, local defects of a shielding layer are difficult to perceive and compensate, performance attenuation cannot be predicted after long-term use, and part of schemes reach standards in laboratory tests but electromagnetic compatibility is deteriorated under complex working conditions of the whole vehicle, so that actual application requirements cannot be met, and large-scale upgrading and application of the shielding noise reduction technology of the high-voltage wire harness of the new energy automobile are restricted. Disclosure of Invention The invention provides a shielding and noise reduction method for a high-voltage wire harness of a new energy automobile, which aims to solve the problems in the prior art. In order to achieve the purpose, the invention adopts the following technical scheme that the shielding and noise reduction method for the high-voltage wire harness of the new energy automobile comprises the following steps: Scanning the high-vol