Method and system for analyzing high-voltage electromagnetic resonance noise of electric vehicle

Abstract

The invention discloses a method and system for analyzing high-voltage electromagnetic resonance noise of an electric vehicle, and relates to the technical field of automobile electromagnetic vibration noise, and the method comprises the steps: obtaining noise information data during the operation of the vehicle, the key parts of the vehicle comprising a high-voltage motor and a battery pack; the collected noise data are preprocessed and analyzed, and the noise data are decomposed into different frequency components. The invention further discloses a system for analyzing the high-voltage electromagnetic resonance noise of the electric vehicle. According to the system of the method for analyzing the high-voltage electromagnetic resonance noise of the electric vehicle, the high-voltage electromagnetic resonance noise of the electric vehicle can be rapidly analyzed through the automatic data acquisition and signal processing flow, the analysis efficiency is improved, and the analysis accuracy is improved by adopting an advanced signal processing algorithm and analysis technology. According to the method, the resonant frequency can be accurately identified, the resonant mechanism can be accurately analyzed, the analysis precision is improved, and the electrical system and structural characteristics of the electric vehicle are considered.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile electromagnetic vibration noise, and in particular to a method and system for analyzing high-voltage electromagnetic resonance noise of electric vehicles. Background Art

[0002] With the increasing popularity of new energy vehicles, pure electric vehicles and hybrid vehicles account for an increasingly high proportion. The electric drive assembly is a key component of the power drive of new energy vehicles. It is significantly different from the traditional internal combustion engine drive system. The vibration and high-frequency noise generated by the electric drive system due to factors such as assembly performance parameters, body structure, and control strategy have become the main excitation sources affecting the NVH performance of the vehicle. Everyone is focusing on the noise problem caused by the electric drive assembly. For new energy vehicles, everyone focuses on the NVH problem of electric drive. There are also many studies and methods on the control strategy of electric drive noise reduction, but there is a lack of attention to the system resonance problem on the vehicle. The vehicle is equipped with many high-voltage components, the electrical circuit system is complex and changeable, and there are many high-voltage inductive and capacitive loads. If the impedance of the high-voltage circuit is not matched, it is easy to cause resonance problems of the high-voltage electrical circuit system, resulting in increased noise and vibration, causing NVH problems for the entire vehicle. In this regard, we propose a method and system for analyzing the high-voltage electromagnetic resonance noise of electric vehicles. Summary of the invention

[0003] In order to solve the above technical problems, a method and system for analyzing high-voltage electromagnetic resonance noise of electric vehicles are provided. This technical solution solves the above problems.

[0004] In order to achieve the above purpose, the technical solution adopted by the present invention is: A method for analyzing high-voltage electromagnetic resonance noise of an electric vehicle, comprising: Acquire noise information data when the vehicle is running, wherein the key parts of the vehicle include: a high-voltage motor and a battery pack; Preprocess and analyze the collected noise data, decompose the noise data into different frequency components, and identify the dominant noise frequency components and their changing patterns; In the decomposed noise signal, the frequency components related to electromagnetic resonance are identified to determine the main source and impact range of the noise; Combined with the electrical system and structural characteristics of electric vehicles, the mechanism of resonance generation is collected and analyzed, and effective suppression measures are proposed by analyzing the mechanism of resonance generation. The analysis of the mechanism of resonance generation includes: analyzing the propagation path, reflection and absorption process of electromagnetic interference, and the influence of vehicle structure on sound wave propagation; By comparing the noise levels before and after analysis, the impact of electromagnetic resonance noise on electric vehicle performance and driver comfort is evaluated.

[0005] Preferably, the collected noise data is preprocessed and analyzed, the noise data is decomposed into different frequency components, and the dominant noise frequency components and their changing rules are identified, specifically including: By setting a threshold to check the values ​​in the noise data that deviate from the normal range, they are judged as outliers and removed; The moving average method is used to smooth the data to reduce the impact of random noise. The expression of the moving average method is:

[0006] In the formula, represents the value of the noise data after moving average processing at the i-th position, m represents the size of the moving average window, i represents the i-th position, j represents the j-th group of data, Represents the value of the jth group of data; The noise data is normalized, where the normalization formula is:

[0007] In the formula, represents the normalized data, x represents the original data, Represents the minimum value in the data. Indicates the maximum value in the data; The preprocessed noise data is subjected to fast Fourier transform to convert the time domain signal into a frequency domain signal. The amplitude and phase information of the noise signal at different frequencies are obtained through Fourier transform. The expression of fast Fourier transform is: Assume the noise signal is x(t), its Fourier transform is:

[0008] In the formula, Represents the Fourier transform result of the noise signal, that is, the component information of the original noise signal at different frequencies. represents the complex exponential function; Draw a spectrum diagram, with the horizontal axis being the frequency and the vertical axis being the amplitude. The spectrum diagram shows the distribution of the noise signal at different frequencies and calculates the power spectrum density:

[0009] In the formula, represents the power spectral density, T represents the duration of the signal; By traversing the spectrum data, find the frequency component with the largest amplitude in the spectrum graph, which is the dominant noise frequency component; The above analysis is performed on the noise data collected at different time points to observe the changes in the dominant noise frequency components, draw a curve of the dominant noise frequency components over time, and analyze their trends and periodicity.

[0010] Preferably, in the decomposed noise signal, the frequency components related to electromagnetic resonance are identified, and the main source and impact range of the noise are determined, specifically including: Collect theoretical resonant frequencies of components that generate electromagnetic resonance in the high-voltage system of electric vehicles to establish an electromagnetic resonance frequency database; The frequency components of the decomposed noise signal are compared with the established electromagnetic resonance frequency database, and the noise frequency components close to the resonance frequency range in the database are marked as frequency components related to electromagnetic resonance; Calculate the frequency components related to electromagnetic resonance and the key parameters of the high-voltage system of the electric vehicle, the key parameters of the high-voltage system include: motor speed and battery current, wherein the calculation formula is:

[0011] In the formula, represents the amplitude of the noise frequency component, Indicates the value of the key parameters of the high voltage system, and are the means of X and Y respectively, and n represents the number of data points; According to the correlation analysis results, the high-voltage system components corresponding to the frequency components related to electromagnetic resonance are determined to be the main sources of noise; By deploying data acquisition modules at different locations of the vehicle, the intensity changes of frequency components related to electromagnetic resonance are observed, and decibels are used to measure the noise intensity. The calculation formula is:

[0012] In the formula, represents the sound pressure level, p represents the measured sound pressure, represents the reference sound pressure; Locations with greater intensities indicate locations that are more affected by noise.

[0013] Preferably, the method steps for collecting and analyzing the mechanism of resonance generation are: Analyze the propagation path of electromagnetic interference: Draw a block diagram of the electric vehicle electrical system to clarify the connection relationship between the key components of the vehicle and the electromagnetic interference path; Use electromagnetic field detection instruments to measure the electromagnetic field strength and frequency distribution at different locations to determine the main propagation paths and areas with high electromagnetic interference in the electrical system; Analyze the coupling mode of electromagnetic interference during the propagation process, and determine the coupling point and coupling mechanism by analyzing the circuit structure and electromagnetic field distribution; Analyze reflection and absorption processes: For the reflection process of electromagnetic interference in the electrical system, the reflection coefficient calculation formula is used to consider the impedance characteristics of the cable and the reflection coefficient factors of the terminal load. The reflection coefficient calculation formula is:

[0014] In the formula, represents the reflection coefficient, represents the terminal load impedance, It represents the characteristic impedance of the transmission line; By measuring the attenuation degree of different materials to electromagnetic interference of specific frequencies through experiments, the absorption process of electromagnetic interference in different materials is analyzed to understand the absorption characteristics of various materials used in electric vehicle structures to electromagnetic interference; Considering the reflection and absorption of electromagnetic interference in space, analyze the reflection and absorption of electromagnetic interference by the vehicle shell and interior structure, as well as the multipath propagation effect in space; Analyze the impact of vehicle structure on sound wave propagation: Establish a three-dimensional structural model of the electric vehicle, analyze the vibration and acoustic characteristics of the vehicle structure, and determine the structural components and frequency range that produce resonance; Measure the vibration acceleration and noise level of the vehicle under different operating conditions, and determine the relationship between the frequency components of vibration and noise and the vehicle structure through spectrum analysis; Consider the impact of holes and gaps in the vehicle structure on the propagation of sound waves, analyze the diffraction and transmission of sound waves in these areas, and their enhancement or weakening effects on noise propagation.

[0015] Preferably, a three-dimensional structural model of an electric vehicle is established, the vibration characteristics and acoustic characteristics of the vehicle structure are analyzed, and the structural components and frequency ranges that generate resonance are determined, specifically including: Collect detailed design drawings of electric vehicles, including body structure, frame, motor installation location, and battery pack layout information; Using 3D modeling software, build a 3D structural model of the electric vehicle based on the collected data; Assign material properties to each component in the model, including density, elastic modulus, and Poisson's ratio, based on actual conditions; Mesh the three-dimensional structural model and discretize it into a finite number of units; According to the actual situation, the boundary conditions are imposed on the model, which simulate the constraints of the vehicle in actual operation. The various loads on the vehicle during operation are measured experimentally, including motor vibration and road excitation, to determine the size and distribution of these loads; Finite element analysis software is used to perform vibration analysis on the three-dimensional structural model after applying boundary conditions and loads, calculate the natural frequency and vibration mode of the model, and understand the vibration characteristics of the vehicle structure at different frequencies. The natural frequency calculation formula is:

[0016] In the formula, K represents the stiffness matrix, M represents the mass matrix, represents the natural frequency, represents the vibration mode vector; Based on the vibration analysis, acoustic analysis is performed to calculate the acoustic response of the vehicle structure using the acoustic finite element method to determine the sound pressure distribution and noise level inside the vehicle, as well as the acoustic characteristics of key parts; By analyzing the results of vibration and acoustic analysis, the structural components and frequency range that produce resonance are determined, the natural frequencies and vibration modes are observed, and the components with large vibration amplitudes at specific frequencies are found. Combined with the results of acoustic analysis, the frequency range with higher noise levels is determined.

[0017] Preferably, the acoustic finite element method is used to calculate the acoustic response of the vehicle structure, determine the sound pressure distribution and noise level inside the vehicle, and the acoustic characteristics of key parts, specifically including: In the acoustic finite element method, for steady-state acoustic problems, the weak form of the acoustic pressure wave equation is expressed as:

[0018] In the formula, V represents the solution area, that is, the interior space of the vehicle, p represents the sound pressure, represents the shape function of the acoustic finite element, represents the medium density, that is, the air density inside the car, c represents the speed of sound, represents the wave number, w represents the angular frequency, S represents the boundary of the solution area, represents the derivative of the sound pressure in the normal direction of the boundary, represents the volume source term, i.e., the intensity of the sound source inside the car; For the discretized finite element model, the above equation is written in matrix form:

[0019] In the formula, K represents the stiffness matrix, M represents the mass matrix, represents the node sound pressure vector, represents the equivalent nodal force vector; Solving the matrix equations yields the node sound pressure vector.

[0020] Preferably, the method steps for proposing effective suppression measures are: The measures to suppress the electromagnetic interference propagation path are: Optimize cable layout and arrange cables to reduce the coupling path of electromagnetic interference; Choose cables with shielding performance to reduce the radiation and conduction of electromagnetic interference. The shielding effectiveness is measured by the shielding coefficient, where the calculation formula is:

[0021] Where SE represents the shielding factor, represents the electric field strength without shielding, Indicates the electric field strength when there is shielding; Install filters at key locations to filter out electromagnetic interference of specific frequencies; The suppression measures for reflection and absorption processes are: Adjust the impedance of the terminal load to match the characteristic impedance of the transmission line to reduce reflection; In areas with strong electromagnetic interference, use absorbing materials to absorb part of the electromagnetic interference energy; Ensure good grounding to reduce common mode current of electromagnetic interference; The measures to suppress the influence of vehicle structure on sound wave propagation are: Strengthen the structural components that produce resonance to increase their natural frequency and avoid overlap with the electromagnetic resonance frequency; Use damping materials in areas with large vibrations to reduce the vibration amplitude and noise radiation of the structure; Seal the holes and gaps in the vehicle structure to reduce the transmission and diffraction of sound waves.

[0022] Preferably, the noise levels before and after the comparative analysis specifically include: Before taking any suppression measures, measure the noise level at multiple locations inside the electric vehicle and key locations outside the vehicle, and record the environmental conditions during the measurement, including but not limited to ambient temperature, humidity, wind speed, and road conditions; After taking measures to suppress electromagnetic resonance noise, measure the noise level again at the same location, under the same operating conditions and under similar environmental conditions; The noise data obtained from the previous and later measurements are classified and sorted according to the measurement location and vehicle operation status; Calculate the difference in noise level at each location and working condition, that is, the noise reduction amount. By comparing these differences, understand the effect of noise suppression measures. The noise reduction amount calculation formula is:

[0023] In the formula, represents the amount of noise reduction, represents the sound pressure level measured earlier, Indicates the sound pressure level measured later.

[0024] Preferably, evaluating the impact of electromagnetic resonance noise on electric vehicle performance and driver comfort specifically includes: Observe whether the power performance parameters of the electric vehicle change before and after suppressing the electromagnetic resonance noise to evaluate the power system performance; Compare the energy consumption of electric vehicles before and after noise suppression to determine whether the suppression measures need to be further optimized to balance the relationship between noise reduction and energy consumption increase; By means of questionnaire survey or subjective evaluation by drivers, drivers are asked to rate the driving comfort before and after the electromagnetic resonance noise is suppressed; According to the relationship standard between the in-vehicle noise level and comfort, it is determined whether the in-vehicle noise level falls within the comfortable range after suppression measures are taken.

[0025] A system for analyzing high-voltage electromagnetic resonance noise of electric vehicles, used to implement a method for analyzing high-voltage electromagnetic resonance noise of electric vehicles, comprising: a data acquisition module, a signal processing module and an analysis and evaluation module; The data acquisition module is used to collect noise data inside the electric vehicle. The data acquisition module includes a sensor unit and a data acquisition unit. The sensor unit is used to capture noise signals, and the data acquisition unit is used to record and transmit data. The signal processing module is used to pre-process and decompose the collected noise data. The signal processing module includes a computer hardware unit and a computer software unit, which are used to execute signal processing algorithms and analysis programs; The analysis and evaluation module is used to analyze the decomposed noise signal, identify the resonant frequency, analyze the resonant mechanism, and evaluate the impact of electromagnetic resonance noise. The analysis and evaluation module includes a signal processing unit and a data analysis unit. The signal processing unit is used to further process the signal data, and the data analysis unit is used to perform data analysis and modeling.

[0026] Compared with the prior art, the present invention has the following beneficial effects: The system for analyzing the high-voltage electromagnetic resonance noise of electric vehicles proposed in the present invention can quickly analyze the high-voltage electromagnetic resonance noise of electric vehicles through automated data acquisition and signal processing procedures, thereby improving the analysis efficiency. By adopting advanced signal processing algorithms and analysis techniques, the present invention can accurately identify the resonance frequency and analyze the resonance mechanism, thereby improving the accuracy of the analysis. The present invention takes into account the electrical system and structural characteristics of the electric vehicle, as well as the influence of electromagnetic interference on the propagation of sound waves, and provides a comprehensive analysis method. The method and device of the present invention can be applied to electric vehicles of different types and models, and have strong scalability. By evaluating the influence of electromagnetic resonance noise, the present invention can provide targeted suggestions for optimizing the driving comfort of electric vehicles, and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of a method for controlling high voltage electromagnetic resonance noise of electric vehicles. DETAILED DESCRIPTION

[0028] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0029] Reference Figure 1 As shown, a method for analyzing high-voltage electromagnetic resonance noise of an electric vehicle comprises: Preparation stage: First, a data acquisition module and corresponding software tools are needed. The sensor unit should be able to accurately capture the noise signal inside the electric vehicle and the current data of the high-voltage circuit, while the data acquisition module should have the ability to collect and process data at high speed. In addition, a detailed experimental plan and data analysis method need to be formulated.

[0030] Experimental stage: During the experimental stage, the sensor units are placed in key locations inside the electric vehicle, such as the high-voltage motor and battery pack. The electric vehicle is then started and allowed to operate under different operating conditions while recording noise and current data. The environment should be kept stable during the experiment to reduce the impact of external factors on the experimental results.

[0031] Data preprocessing: The collected noise and current data contain other noise, interference and outliers. In the data preprocessing stage, filters and denoising algorithms are used to remove these interferences and outliers to obtain clear noise and current, and perform data normalization for subsequent analysis.

[0032] Signal decomposition: Use Fourier transform signal processing algorithm to decompose noise and current signals. The purpose of this step is to convert noise and current signals from time domain to frequency domain, so as to more easily identify the dominant noise and current frequency components and their changing laws. By decomposing noise and current signals, noise spectrum and current harmonic diagram can be obtained, which is very important for subsequent analysis.

[0033] Resonance frequency identification: In the decomposed noise and current spectra, look for frequency components related to electromagnetic resonance. These frequency components usually appear as obvious peaks or specific frequency patterns. By identifying the resonant frequency, the main source of noise and the scope of influence can be determined. This step is crucial for subsequent resonance mechanism analysis and impact assessment.

[0034] Resonance mechanism analysis: Combined with the electrical system and structural characteristics of electric vehicles, the electrical impedance parameters of the corresponding high-voltage components are extracted and the resonance mechanism is analyzed through modeling and simulation. This includes analyzing the propagation path, reflection and absorption process of electromagnetic interference, and the impact of vehicle structure on sound wave propagation. By deeply understanding the resonance mechanism, effective suppression measures can be proposed. This step requires a comprehensive analysis combining theoretical models and experimental data.

[0035] Impact assessment: Based on the analysis results, the impact of electromagnetic resonance noise on electric vehicle performance and driver comfort is assessed. This can be done by comparing the noise levels before and after the analysis and assessing the impact on the driver. By assessing the impact, a basis is provided for subsequent optimization design.

[0036] Result output: Output the analysis results in the form of graphs or tables to provide a basis for subsequent optimization design. In addition, a detailed analysis report can be written so that other people can understand and use these results.

[0037] Verification and iteration: To verify the accuracy and reliability of the analysis results, experimental verification can be performed. This can be done by testing on actual electric vehicles. Based on the experimental results, the analysis method is iteratively improved to improve the accuracy and reliability of the analysis.

[0038] Preprocess and analyze the collected noise data, decompose the noise data into different frequency components, identify the dominant noise frequency components and their changing rules, including: Carefully check the noisy data by setting specific thresholds. In this process, once the data is found to have values ​​that deviate from the normal range, they are identified as outliers. Then, these outliers are decisively removed to ensure the accuracy and reliability of the data for subsequent analysis; The moving average method is used to smooth the data after preliminary processing. The purpose of this is to reduce the impact of random noise on the data, making the data more stable and easier to analyze. The expression of the moving average method is:

[0039] In the formula, represents the value of the noise data after moving average processing at the i-th position, m represents the size of the moving average window, i represents the i-th position, j represents the j-th group of data, Represents the value of the jth group of data; Normalize the noise data. Normalization can make data of different magnitudes on the same scale, which is convenient for subsequent calculations and analyses. The normalization formula is:

[0040] In the formula, represents the normalized data, x represents the original data, Represents the minimum value in the data. Indicates the maximum value in the data; Perform fast Fourier transform on the preprocessed noise data to convert the time domain signal into a frequency domain signal. Through Fourier transform, the amplitude and phase information of the noise signal at different frequencies can be obtained. On this basis, a spectrum diagram is drawn, in which the horizontal axis is set as frequency and the vertical axis is amplitude. Through such a spectrum diagram, the distribution of the noise signal at different frequencies can be clearly seen. At the same time, the power spectral density needs to be calculated to further understand the characteristics of the noise signal. The expression of fast Fourier transform is: Assume the noise signal is x(t), its Fourier transform is:

[0041] In the formula, Represents the Fourier transform result of the noise signal, that is, the component information of the original noise signal at different frequencies. represents the complex exponential function; Draw a spectrum diagram, with the horizontal axis being the frequency and the vertical axis being the amplitude. The spectrum diagram shows the distribution of the noise signal at different frequencies and calculates the power spectrum density:

[0042] In the formula, represents the power spectral density, T represents the duration of the signal; By traversing the spectrum data, find the frequency component with the largest amplitude in the spectrum graph, which is the dominant noise frequency component; The above series of analysis operations are performed on the noise data collected at different time points. By observing the changes in the dominant noise frequency components, a curve of the dominant noise frequency components changing with time is drawn. From this curve, its trend and periodicity can be deeply analyzed, providing an important basis for further studying noise characteristics and taking corresponding suppression measures.

[0043] In the decomposed noise signal, the frequency components related to electromagnetic resonance are identified, and the main sources and impact range of the noise are determined, including: Collect the theoretical resonant frequencies of the components in the high-voltage system of electric vehicles that will produce electromagnetic resonance. In the process of collecting, ensure the accuracy and completeness of the data, and then establish an electromagnetic resonance frequency database. This database will provide an important reference for subsequent analysis; The frequency components of the decomposed noise signal are compared with the established electromagnetic resonance frequency database. During the comparison, the noise frequency components that are close to the resonance frequency range in the database or just within the resonance frequency range in the database are marked as frequency components related to electromagnetic resonance. Through such marking, the parts related to electromagnetic resonance can be more clearly identified; The relationship between the frequency components related to electromagnetic resonance and the key parameters of the high-voltage system of the electric vehicle is calculated. The key parameters of the high-voltage system include the motor speed and the battery current. By calculating the relationship between these parameters, the influence of electromagnetic resonance on the high-voltage system is further understood. The key parameters of the high-voltage system include: motor speed and battery current. The calculation formula is:

[0044] In the formula, represents the amplitude of the noise frequency component, Indicates the value of the key parameters of the high voltage system, and are the means of X and Y respectively, and n represents the number of data points; According to the results of correlation analysis, the high-voltage system component corresponding to the frequency component related to electromagnetic resonance is determined. This component is the main source of noise. Through such analysis, the root cause of noise can be accurately found, providing a clear direction for subsequent effective suppression measures. By deploying data acquisition modules at different locations of the vehicle, the intensity changes of frequency components related to electromagnetic resonance are observed. When measuring noise intensity, decibels are used as the unit. The data collected at different locations can reflect the degree to which various parts of the vehicle are affected by noise. The calculation formula is:

[0045] In the formula, represents the sound pressure level, p represents the measured sound pressure, represents the reference sound pressure; Locations with greater intensity indicate that they are more affected by noise and require special attention and appropriate measures to reduce the impact of noise.

[0046] The method steps for collecting and analyzing the mechanism of resonance generation are: Analyze the propagation path of electromagnetic interference: Draw a block diagram of the electric vehicle electrical system. In this block diagram, the connection relationship between the key components of the vehicle should be clearly shown, and the path of electromagnetic interference should be clearly presented. Through such a block diagram, the architecture of the entire electrical system can be intuitively understood, providing a basis for the subsequent analysis of the propagation of electromagnetic interference. The connection of each key component becomes a channel for the propagation of electromagnetic interference, so it must be accurately depicted; Use professional electromagnetic field detection instruments to measure at different locations of the electric vehicle. The measurement content includes electromagnetic field strength and frequency distribution. Through measurements at different locations, the main propagation paths of electromagnetic interference in the electrical system and areas with high intensity are determined. These areas are often where special attention and measures need to be taken. During the measurement process, the accuracy and reliability of the instrument must be ensured, and the measurement points must be selected to fully understand the distribution of electromagnetic interference. Analyze the coupling mode of electromagnetic interference during the propagation process. By analyzing the circuit structure and electromagnetic field distribution, determine the coupling point and coupling mechanism. The coupling modes include capacitive coupling and inductive coupling. Understanding the coupling mode helps to find the specific path and cause of electromagnetic interference propagation. When analyzing the circuit structure, the layout of the circuit and the parameters of the components should be considered. When analyzing the electromagnetic field distribution, the electromagnetic field theory and calculation methods should be used to determine the strength and direction of the electromagnetic field. Analyze reflection and absorption processes: The reflection coefficient calculation formula is used to analyze the reflection process of electromagnetic interference in the electrical system. When calculating the reflection coefficient, the impedance characteristics of the cable and the reflection coefficient of the terminal load must be considered. The impedance characteristics of the cable will affect the reflection degree of the electromagnetic interference, and the reflection coefficient of the terminal load depends on the nature and connection method of the load. By accurately calculating the reflection coefficient, we can understand the changes in the electromagnetic interference during the reflection process and provide a basis for taking corresponding suppression measures. The reflection coefficient calculation formula is:

[0047] In the formula, represents the reflection coefficient, represents the terminal load impedance, It represents the characteristic impedance of the transmission line; Through experiments, the attenuation degree of different materials to electromagnetic interference of specific frequencies is measured, and the absorption process of electromagnetic interference in different materials is analyzed. It is very important to understand the absorption characteristics of various materials used in the structure of electric vehicles to electromagnetic interference. Different materials have different absorption characteristics. Some materials have better absorption effects on electromagnetic interference of specific frequencies, while some materials have poor absorption effects. Through experimental measurements, it can be determined which materials are used to suppress electromagnetic interference, and in which parts these materials can achieve the best effect; It is also necessary to consider the reflection and absorption of electromagnetic interference in space, and analyze the reflection and absorption of electromagnetic interference by the vehicle shell and interior structure, as well as the multipath propagation effect in space. The material and shape of the vehicle shell and interior will affect the reflection and absorption of electromagnetic interference. Some materials have better reflection properties and reflect electromagnetic interference back to the electrical system, while other materials have better absorption properties and convert electromagnetic interference into heat energy. In addition, the multipath propagation effect in space will also affect the distribution and intensity of electromagnetic interference. Multipath propagation means that electromagnetic interference reaches the receiving point through different paths during the propagation process. The lengths and propagation conditions of these paths are different, which will cause the phase and amplitude of the electromagnetic interference to change; Analyze the impact of vehicle structure on sound wave propagation: Establish a three-dimensional structural model of the electric vehicle and analyze the vibration and acoustic characteristics of the vehicle structure. By establishing a three-dimensional structural model, the characteristics and complexity of the vehicle structure can be more intuitively understood. When analyzing the vibration characteristics, it is necessary to consider the various forces and vibration sources to which the vehicle is subjected during operation, and determine the structural components and frequency range that produce resonance. When analyzing the acoustic characteristics, it is necessary to consider the propagation path, reflection, and absorption of sound waves in the vehicle structure. Measure the vibration acceleration and noise level of the vehicle under different operating conditions. Through spectrum analysis, determine the relationship between the frequency components of vibration and noise and the vehicle structure. When measuring vibration acceleration, it is necessary to ensure the accuracy of the measurement results. When measuring noise levels, it is necessary to take into account the noise differences at different locations and the influence of environmental noise. Through spectrum analysis, the frequency components of vibration and noise are linked to the characteristics of the vehicle structure to find out the main structural components and propagation paths that generate noise; Consider the impact of holes and gaps in the vehicle structure on the propagation of sound waves, analyze the diffraction and transmission of sound waves in these parts, and the enhancement or weakening effect on noise propagation. Holes and gaps will change the propagation path and intensity of sound waves, which will cause the noise to be enhanced or weakened. When analyzing, it is necessary to use acoustic theory and calculation methods to determine the propagation characteristics of sound waves in these parts. At the same time, it is necessary to consider that the size and shape of holes and gaps will change under different operating conditions of the vehicle, thereby affecting the propagation of noise.

[0048] The use process of the present invention is as follows: obtaining vehicle operation noise information data, preprocessing and analyzing the noise data, decomposing it into different frequency components and identifying the dominant components and their changing rules, identifying the electromagnetic resonance-related frequency components in the decomposed signal to determine the main source of noise and the scope of influence, analyzing the resonance generation mechanism in combination with the electrical system and structural characteristics of the electric vehicle, proposing effective suppression measures, and evaluating the impact of electromagnetic resonance noise on the performance of the electric vehicle and the comfort of the driver by comparing and analyzing the noise levels before and after.

[0049] In summary, the advantages of the present invention are: improving analysis efficiency through automated processes, improving analysis accuracy by using advanced algorithms and technologies, providing a comprehensive analysis method considering the characteristics of electric vehicles and the impact of electromagnetic interference, being applicable to different types of electric vehicles and having scalability, and providing suggestions for optimizing driving comfort by evaluating the impact of noise, which is practical.

[0050] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for analyzing high-voltage electromagnetic resonance noise of electric vehicles, characterized in that: include: Acquire noise information data when the vehicle is running, wherein the key parts of the vehicle include: a high-voltage motor and a battery pack; Preprocess and analyze the collected noise data, decompose the noise data into different frequency components, and identify the dominant noise frequency components and their changing patterns; In the decomposed noise signal, the frequency components related to electromagnetic resonance are identified to determine the main source and impact range of the noise; Combined with the electrical system and structural characteristics of electric vehicles, the mechanism of resonance generation is collected and analyzed, and effective suppression measures are proposed by analyzing the mechanism of resonance generation. The analysis of the mechanism of resonance generation includes: analyzing the propagation path, reflection and absorption process of electromagnetic interference, and the influence of vehicle structure on sound wave propagation; By comparing the noise levels before and after analysis, the impact of electromagnetic resonance noise on electric vehicle performance and driver comfort is evaluated.

2. A method for analyzing high-voltage electromagnetic resonance noise of electric vehicles according to claim 1, characterized in that: Preprocess and analyze the collected noise data, decompose the noise data into different frequency components, identify the dominant noise frequency components and their changing rules, including: By setting a threshold to check the values ​​in the noise data that deviate from the normal range, they are judged as outliers and removed; The moving average method is used to smooth the data to reduce the impact of random noise. The expression of the moving average method is: In the formula, represents the value of the noise data after moving average processing at the i-th position, m represents the size of the moving average window, i represents the i-th position, j represents the j-th group of data, Represents the value of the jth group of data; The noise data is normalized, where the normalization formula is: In the formula, represents the normalized data, x represents the original data, Represents the minimum value in the data. Indicates the maximum value in the data; The pre-processed noise data is subjected to fast Fourier transform to convert the time domain signal into a frequency domain signal. The amplitude and phase information of the noise signal at different frequencies are obtained through Fourier transform. The expression of fast Fourier transform is: Assume the noise signal is x(t), its Fourier transform is: In the formula, Represents the Fourier transform result of the noise signal, that is, the component information of the original noise signal at different frequencies. represents the complex exponential function; Draw a spectrum diagram, with the horizontal axis being the frequency and the vertical axis being the amplitude. The spectrum diagram shows the distribution of the noise signal at different frequencies and calculates the power spectrum density: In the formula, represents the power spectral density, T represents the duration of the signal; By traversing the spectrum data, find the frequency component with the largest amplitude in the spectrum graph, which is the dominant noise frequency component; The above analysis is performed on the noise data collected at different time points to observe the changes in the dominant noise frequency components, draw a curve of the dominant noise frequency components over time, and analyze their trends and periodicity.

3. A method for analyzing high-voltage electromagnetic resonance noise of electric vehicles according to claim 1, characterized in that: In the decomposed noise signal, the frequency components related to electromagnetic resonance are identified, and the main sources and impact range of the noise are determined, including: Collect theoretical resonant frequencies of components that generate electromagnetic resonance in the high-voltage system of electric vehicles to establish an electromagnetic resonance frequency database; The frequency components of the decomposed noise signal are compared with the established electromagnetic resonance frequency database, and the noise frequency components close to the resonance frequency range in the database are marked as frequency components related to electromagnetic resonance; Calculate the frequency components related to electromagnetic resonance and the key parameters of the high-voltage system of the electric vehicle, the key parameters of the high-voltage system include: motor speed and battery current, wherein the calculation formula is: In the formula, represents the amplitude of the noise frequency component, Indicates the value of the key parameters of the high voltage system, and are the means of X and Y respectively, and n represents the number of data points; According to the correlation analysis results, the high-voltage system components corresponding to the frequency components related to electromagnetic resonance are determined to be the main sources of noise; By deploying data acquisition modules at different locations of the vehicle, the intensity changes of frequency components related to electromagnetic resonance are observed, and decibels are used to measure the noise intensity. The calculation formula is: In the formula, represents the sound pressure level, p represents the measured sound pressure, represents the reference sound pressure; Locations with greater intensities indicate locations that are more affected by noise.

4. The method for analyzing high-voltage electromagnetic resonance noise of electric vehicles according to claim 1, characterized in that: The method steps for collecting and analyzing the mechanism of resonance generation are: Analyze the propagation path of electromagnetic interference: Draw a block diagram of the electric vehicle electrical system to clarify the connection relationship between the key components of the vehicle and the electromagnetic interference path; Use electromagnetic field detection instruments to measure the electromagnetic field strength and frequency distribution at different locations to determine the main propagation paths and areas with high electromagnetic interference in the electrical system; Analyze the coupling mode of electromagnetic interference during the propagation process, and determine the coupling point and coupling mechanism by analyzing the circuit structure and electromagnetic field distribution; Analyze reflection and absorption processes: For the reflection process of electromagnetic interference in the electrical system, the reflection coefficient calculation formula is used to consider the impedance characteristics of the cable and the reflection coefficient factors of the terminal load. The reflection coefficient calculation formula is: In the formula, represents the reflection coefficient, represents the terminal load impedance, It represents the characteristic impedance of the transmission line; By measuring the attenuation degree of different materials to electromagnetic interference of specific frequencies through experiments, the absorption process of electromagnetic interference in different materials is analyzed to understand the absorption characteristics of various materials used in electric vehicle structures to electromagnetic interference; Considering the reflection and absorption of electromagnetic interference in space, analyze the reflection and absorption of electromagnetic interference by the vehicle shell and interior structure, as well as the multipath propagation effect in space; Analyze the impact of vehicle structure on sound wave propagation: Establish a three-dimensional structural model of the electric vehicle, analyze the vibration and acoustic characteristics of the vehicle structure, and determine the structural components and frequency range that produce resonance; Measure the vibration acceleration and noise level of the vehicle under different operating conditions, and determine the relationship between the frequency components of vibration and noise and the vehicle structure through spectrum analysis; Consider the impact of holes and gaps in the vehicle structure on the propagation of sound waves, analyze the diffraction and transmission of sound waves in these areas, and their enhancement or weakening effects on noise propagation.

5. A method for analyzing high-voltage electromagnetic resonance noise of electric vehicles according to claim 4, characterized in that: Establish a three-dimensional structural model of the electric vehicle, analyze the vibration and acoustic characteristics of the vehicle structure, and determine the structural components and frequency range that produce resonance, including: Collect detailed design drawings of electric vehicles, including body structure, frame, motor installation location, and battery pack layout information; Using 3D modeling software, build a 3D structural model of the electric vehicle based on the collected data; Assign material properties to each component in the model, including density, elastic modulus, and Poisson's ratio, based on actual conditions; Mesh the three-dimensional structural model and discretize it into a finite number of units; According to the actual situation, the boundary conditions are imposed on the model, which simulate the constraints of the vehicle in actual operation. The various loads on the vehicle during operation are measured experimentally, including motor vibration and road excitation, to determine the size and distribution of these loads; Finite element analysis software is used to perform vibration analysis on the three-dimensional structural model after applying boundary conditions and loads, calculate the natural frequency and vibration mode of the model, and understand the vibration characteristics of the vehicle structure at different frequencies. The natural frequency calculation formula is: In the formula, K represents the stiffness matrix, M represents the mass matrix, represents the natural frequency, represents the vibration mode vector; Based on the vibration analysis, acoustic analysis is performed to calculate the acoustic response of the vehicle structure using the acoustic finite element method to determine the sound pressure distribution and noise level inside the vehicle, as well as the acoustic characteristics of key parts; By analyzing the results of vibration and acoustic analysis, the structural components and frequency range that produce resonance are determined, the natural frequencies and vibration modes are observed, and the components with large vibration amplitudes at specific frequencies are found. Combined with the results of acoustic analysis, the frequency range with higher noise levels is determined.

6. A method for analyzing high-voltage electromagnetic resonance noise of electric vehicles according to claim 6, characterized in that: The acoustic finite element method is used to calculate the acoustic response of the vehicle structure, determine the sound pressure distribution and noise level inside the vehicle, and the acoustic characteristics of key parts, including: In the acoustic finite element method, for steady-state acoustic problems, the weak form of the acoustic pressure wave equation is expressed as: In the formula, V represents the solution area, that is, the interior space of the vehicle, p represents the sound pressure, represents the shape function of the acoustic finite element, represents the medium density, that is, the air density inside the car, c represents the speed of sound, represents the wave number, w represents the angular frequency, S represents the boundary of the solution area, represents the derivative of the sound pressure in the normal direction of the boundary, represents the volume source term, i.e., the intensity of the sound source inside the car; For the discretized finite element model, the above equation is written in matrix form: In the formula, K represents the stiffness matrix, M represents the mass matrix, represents the node sound pressure vector, represents the equivalent nodal force vector; Solving the matrix equations yields the node sound pressure vector.

7. The method for analyzing high-voltage electromagnetic resonance noise of an electric vehicle according to claim 1, characterized in that: The method steps for proposing effective suppression measures are: The measures to suppress the electromagnetic interference propagation path are: Optimize cable layout and arrange cables to reduce the coupling path of electromagnetic interference; Choose cables with shielding performance to reduce the radiation and conduction of electromagnetic interference. The shielding effectiveness is measured by the shielding coefficient, where the calculation formula is: Where SE represents the shielding factor, represents the electric field strength without shielding, Indicates the electric field strength when there is shielding; Install filters at key locations to filter out electromagnetic interference of specific frequencies; The suppression measures for reflection and absorption processes are: Adjust the impedance of the terminal load to match the characteristic impedance of the transmission line to reduce reflection; In areas with strong electromagnetic interference, use absorbing materials to absorb part of the electromagnetic interference energy; Ensure good grounding to reduce common mode current of electromagnetic interference; The measures to suppress the influence of vehicle structure on sound wave propagation are: Strengthen the structural components that produce resonance to increase their natural frequency and avoid overlap with the electromagnetic resonance frequency; Use damping materials in areas with large vibrations to reduce the vibration amplitude and noise radiation of the structure; Seal the holes and gaps in the vehicle structure to reduce the transmission and diffraction of sound waves.

8. The method for analyzing high-voltage electromagnetic resonance noise of electric vehicles according to claim 1, characterized in that: The noise levels before and after the comparative analysis specifically include: Before taking any suppression measures, measure the noise level at multiple locations inside the electric vehicle and key locations outside the vehicle, and record the environmental conditions during the measurement, including but not limited to ambient temperature, humidity, wind speed, and road conditions; After taking measures to suppress electromagnetic resonance noise, measure the noise level again at the same location, under the same operating conditions and under similar environmental conditions; The noise data obtained from the previous and later measurements are classified and sorted according to the measurement location and vehicle operation status; Calculate the difference in noise level at each location and working condition, that is, the noise reduction amount. By comparing these differences, understand the effect of noise suppression measures. The noise reduction amount calculation formula is: In the formula, represents the amount of noise reduction, represents the sound pressure level measured earlier, Indicates the sound pressure level measured later.

9. The method for analyzing high-voltage electromagnetic resonance noise of electric vehicles according to claim 1, characterized in that: Evaluating the impact of electromagnetic resonance noise on electric vehicle performance and driver comfort specifically includes: Observe whether the power performance parameters of the electric vehicle change before and after suppressing the electromagnetic resonance noise to evaluate the power system performance; Compare the energy consumption of electric vehicles before and after noise suppression to determine whether the suppression measures need to be further optimized to balance the relationship between noise reduction and energy consumption increase; By means of questionnaire survey or subjective evaluation by drivers, drivers are asked to rate the driving comfort before and after the electromagnetic resonance noise is suppressed; According to the relationship standard between the in-vehicle noise level and comfort, it is determined whether the in-vehicle noise level falls within the comfortable range after suppression measures are taken.

10. A system for analyzing high-voltage electromagnetic resonance noise of electric vehicles, characterized in that: A method for analyzing high-voltage electromagnetic resonance noise of an electric vehicle as claimed in any one of claims 1 to 9, comprising: a data acquisition module, a signal processing module and an analysis and evaluation module; The data acquisition module is used to collect noise data inside the electric vehicle. The data acquisition module includes a sensor unit and a data acquisition unit. The sensor unit is used to capture noise signals, and the data acquisition unit is used to record and transmit data. The signal processing module is used to pre-process and decompose the collected noise data. The signal processing module includes a computer hardware unit and a computer software unit, which are used to execute signal processing algorithms and analysis programs; The analysis and evaluation module is used to analyze the decomposed noise signal, identify the resonant frequency, analyze the resonant mechanism, and evaluate the impact of electromagnetic resonance noise. The analysis and evaluation module includes a signal processing unit and a data analysis unit. The signal processing unit is used to further process the signal data, and the data analysis unit is used to perform data analysis and modeling.

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