Method for analyzing vibration transmission performance of electric drive assembly of new energy automobile

Abstract

The invention discloses a method for analyzing the vibration transmission performance of an electric drive assembly of a new energy automobile, and the method comprises the steps: arranging excitation sources at a plurality of vibration transmission points of the electric drive assembly, enabling the vibration transmission points to comprise a flexible connection point, a rigid supporting point and a cover plate geometric center point, synchronously collecting a vibration acceleration signal and a force sensing signal, respectively calculating comprehensive impedance coefficients for the flexible connecting point, the rigid supporting point and the geometric center point of the cover plate, finally adding the comprehensive impedance coefficients of all vibration transmission points to obtain a total impedance coefficient, and further rating the vibration transmission performance of the electric drive assembly. According to the method, on the premise that no whole vehicle resource support exists in the early stage, rapid product iteration is achieved, the development period is shortened, risk problems are recognized in advance, and the purpose of saving the whole vehicle test cost is achieved.

Description

Technical Field

[0001] This invention relates to the field of electric drive technology for new energy vehicles, and specifically to a method for analyzing the vibration transmission performance of electric drive assemblies for new energy vehicles. Background Technology

[0002] With the continuous development of new energy vehicle technology, the electric drive unit, as one of the core components of new energy vehicles, directly affects the market competitiveness and positioning of the entire vehicle. The electric drive unit mainly includes components such as the motor, transmission, and controller, responsible for providing power to the new energy vehicle. Especially during vehicle operation, the vibration and noise characteristics of the electric drive unit play a crucial role in the driving experience. Therefore, effectively suppressing the vibration and noise of the electric drive unit has become an important issue in the design and development of new energy vehicles.

[0003] Currently, the vibration and noise performance of electric drive systems is typically optimized through iterative processes involving repeated prototype fabrication, vehicle installation, vehicle testing, problem analysis, and new prototype optimization. However, this process requires significant time and financial investment and is characterized by long cycles and high costs. Traditional vibration and noise performance optimization processes often struggle to achieve effective early prediction during the vehicle testing phase and rely heavily on dynamic testing of actual vehicles, making it difficult to achieve rapid evaluation and timely feedback.

[0004] To address this issue, new methods based on the impedance performance analysis of vibration transmission points in electric drive assemblies have been proposed in recent years. The impedance performance of vibration transmission points in electric drive assemblies can intuitively, quickly, and clearly reflect the vibration and noise characteristics of the electric drive assembly under vehicle operating conditions, and can be obtained through static testing. This method has advantages such as short testing cycle, low cost, and simple operation. It allows for the early assessment of the motor's ability to suppress vibration and noise even without full-vehicle testing resources, providing important basis for subsequent product optimization.

[0005] However, current methods for analyzing and evaluating the impedance performance of vibration transmission points in electric drive systems are incomplete, lacking a systematic and standardized set of analytical tools. Effective analytical methods, through forward design and development, can help development teams identify and resolve potential vibration and noise issues in the early design stages of electric drive systems, thereby reducing reliance on vehicle testing, shortening development cycles, lowering development risks, and saving on vehicle testing costs. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a vibration transmission performance analysis method that can quickly and accurately feed back the vibration and noise characteristics of the electric drive assembly under vehicle operating conditions, and help improve the efficiency of vibration and noise performance optimization of new energy vehicles.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for analyzing the vibration transmission performance of an electric drive assembly in a new energy vehicle includes:

[0009] (1) Excitation sources are arranged at multiple vibration transmission points of the electric drive assembly, and vibration acceleration signals and force sensing signals are collected synchronously. Vibration displacement is calculated based on vibration acceleration signals, and impedance frequency domain data of each vibration transmission point is generated by combining force sensing signals. Vibration transmission points include flexible connection points, rigid support points and cover plate geometric center points.

[0010] (2) For flexible connection points: Determine the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency in the frequency band above the cutoff frequency, calculate the equivalent damping coefficient based on the impedance minimum value, combine the impedance minimum value and its corresponding frequency and the equivalent damping coefficient to calculate the single-point impedance coefficient, and calculate the comprehensive impedance coefficient of the flexible connection points by combining all flexible connection points.

[0011] For rigid support points: Determine the cutoff frequency. In the frequency band above the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency and at least one impedance maximum value and its corresponding frequency. Calculate the average impedance in the frequency band above the cutoff frequency. Combine the impedance minimum value and its corresponding frequency, the impedance maximum value and its corresponding frequency, and the average impedance to calculate the single-point impedance coefficient. Integrate all rigid support points to calculate the comprehensive impedance coefficient of the rigid support points.

[0012] For the geometric center point of the cover plate: determine the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency and at least one impedance maximum value and its corresponding frequency in the frequency band above the cutoff frequency, calculate the equivalent damping coefficient based on the impedance minimum value, and calculate the average impedance in the frequency band above the cutoff frequency. Combine the impedance minimum value and its corresponding frequency, the equivalent damping coefficient and the average impedance to calculate the single-point impedance coefficient. Combine all the geometric center points of the cover plate to calculate the comprehensive impedance coefficient of the cover plate.

[0013] (3) Add the comprehensive impedance coefficients of the flexible connection point, the rigid support point, and the cover plate to obtain the total impedance coefficient, and rate the vibration transmission performance of the electric drive assembly based on the total impedance coefficient.

[0014] As an optimization, in step (1), the flexible connection point includes a flexible bushing attachment point, and the rigid support point includes a bearing housing mounting point.

[0015] As an optimization, in step (1), the excitation source adopts the linear step sweep frequency method with equal time and equal amplitude.

[0016] As an optimization, in step (2), when calculating the single-point impedance coefficient of the flexible connection point, the single-point unidirectional impedance coefficient of the flexible connection point is calculated sequentially in the X, Y, and Z directions, and the comprehensive impedance coefficient of the flexible connection point is calculated based on the formula:

[0017]

[0018] Where ZZK is the composite impedance coefficient of the flexible connection point, n is the number of flexible connection points, and ZK jx ZK represents the impedance coefficient in the X direction of the j-th flexible connection point. jy ZK represents the impedance coefficient in the Y direction of the j-th flexible connection point. jz This represents the impedance coefficient in the Z direction of the j-th flexible connection point.

[0019] As an optimization, in step (2), the cutoff frequency is determined in the following way: based on the impedance frequency domain data, with frequency as the abscissa and impedance frequency domain value as the ordinate, an impedance frequency domain curve is plotted, the impedance slope between adjacent frequency points is calculated, and the frequency corresponding to the first occurrence of a negative slope is taken as the cutoff frequency.

[0020] As an optimization, a preset frequency is set. If no negative slope occurs within the preset frequency, the preset frequency is set as the cutoff frequency.

[0021] As an optimization, in step (3), a pre-defined rating and grading rule is set, and the rating is determined based on the calculated total impedance coefficient.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) By identifying the key points of vibration transmission in the electric drive assembly, a clear reference basis is provided for product design and optimization. Through detailed analysis and testing of these key points, the vibration and noise characteristics of each component of the electric drive assembly during vehicle operation can be effectively identified and evaluated, thereby providing important data support for subsequent optimization design.

[0024] (2) The method of this application can quickly obtain the vibration transmission point impedance performance of the electric drive assembly under static conditions. Compared with the traditional dynamic test, the static test has the advantages of short cycle and low cost, effectively avoiding the limitation of relying on the whole vehicle resources in the traditional method, improving the efficiency and feasibility of the test, and reducing the number of whole vehicle tests and costs.

[0025] (3) The development team can promptly identify potential vibration and noise problems in the early design stage of the electric drive assembly, avoiding repeated prototype manufacturing and vehicle testing in the traditional method, which significantly shortens the product development cycle. This not only accelerates the product from design to production, but also effectively identifies and avoids potential risks in the early stage, reducing uncertainty in the development process. Attached Figure Description

[0026] Figure 1 This is a frequency domain impedance curve of the flexible bushing attachment point in this invention.

[0027] Figure 2 This is a frequency domain impedance curve of the bearing housing mounting point in this invention;

[0028] Figure 3 This is the frequency domain impedance curve of the geometric center point of the cover plate in this invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] The method for analyzing the vibration transmission performance of the electric drive assembly of new energy vehicles in this specific embodiment includes:

[0031] (1) Excitation sources are arranged at multiple vibration transmission points of the electric drive assembly, and vibration acceleration signals and force sensing signals are collected synchronously. Vibration displacement is calculated based on vibration acceleration signals, and impedance frequency domain data of each vibration transmission point is generated by combining force sensing signals. Vibration transmission points include flexible connection points, rigid support points and cover plate geometric center points.

[0032] (2) For flexible connection points: Determine the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency in the frequency band above the cutoff frequency, calculate the equivalent damping coefficient based on the impedance minimum value, combine the impedance minimum value and its corresponding frequency and the equivalent damping coefficient to calculate the single-point impedance coefficient, and calculate the comprehensive impedance coefficient of the flexible connection points by combining all flexible connection points.

[0033] For rigid support points: Determine the cutoff frequency. In the frequency band above the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency and at least one impedance maximum value and its corresponding frequency. Calculate the average impedance in the frequency band above the cutoff frequency. Combine the impedance minimum value and its corresponding frequency, the impedance maximum value and its corresponding frequency, and the average impedance to calculate the single-point impedance coefficient. Integrate all rigid support points to calculate the comprehensive impedance coefficient of the rigid support points.

[0034] For the geometric center point of the cover plate: determine the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency and at least one impedance maximum value and its corresponding frequency in the frequency band above the cutoff frequency, calculate the equivalent damping coefficient based on the impedance minimum value, and calculate the average impedance in the frequency band above the cutoff frequency. Combine the impedance minimum value and its corresponding frequency, the equivalent damping coefficient and the average impedance to calculate the single-point impedance coefficient. Combine all the geometric center points of the cover plate to calculate the comprehensive impedance coefficient of the cover plate.

[0035] (3) Add the comprehensive impedance coefficients of the flexible connection point, the rigid support point, and the cover plate to obtain the total impedance coefficient, and rate the vibration transmission performance of the electric drive assembly based on the total impedance coefficient.

[0036] In step (1), the flexible connection point includes a flexible bushing attachment point, and the rigid support point includes a bearing housing mounting point.

[0037] In step (1), the excitation source adopts the linear step sweep frequency method with equal time and equal amplitude.

[0038] In step (2), when calculating the single-point impedance coefficient of the flexible connection point, the single-point unidirectional impedance coefficient of the flexible connection point is calculated sequentially in the X, Y, and Z directions, and the comprehensive impedance coefficient of the flexible connection point is calculated based on the formula:

[0039]

[0040] Where ZZK is the composite impedance coefficient of the flexible connection point, n is the number of flexible connection points, and ZK jx ZK represents the impedance coefficient in the X direction of the j-th flexible connection point. jy ZK represents the impedance coefficient in the Y direction of the j-th flexible connection point. jz This represents the impedance coefficient in the Z direction of the j-th flexible connection point.

[0041] In step (2), the cutoff frequency is determined in the following way: based on the impedance frequency domain data, an impedance frequency domain curve is plotted with frequency as the abscissa and impedance frequency domain value as the ordinate, the impedance slope between adjacent frequency points is calculated, and the frequency corresponding to the first occurrence of a negative slope is taken as the cutoff frequency.

[0042] Set a preset frequency. If no negative slope occurs within the preset frequency range, then set the preset frequency as the cutoff frequency.

[0043] In step (3), a pre-defined rating and grading rule is set, and the rating is determined based on the calculated total impedance coefficient.

[0044] In the specific implementation process, the excitation source, force sensor, and vibration acceleration sensor are sequentially arranged at the aforementioned vibration transmission points. A linear frequency sweep excitation method with equal time and equal amplitude is adopted, i.e., starting with an excitation frequency of 1Hz, excitation is performed for one second; then the excitation frequency is adjusted to 2Hz and excitation continues for one second; this process is repeated until 3000Hz is reached. Vibration acceleration signal data and force sensor signal data are recorded throughout the entire process. The vibration acceleration signal is processed using the following formula:

[0045] d(f)=a(f) / ((2πf)*(2πf))

[0046] In the formula, f represents the actual excitation frequency of the excitation source, d(f) represents the vibration displacement value calculated at frequency f, and a(f) represents the vibration acceleration value obtained by testing at frequency f.

[0047] Then calculate the corresponding impedance frequency domain value according to the following formula:

[0048] k(f)=F(f) / d(f)

[0049] In the formula: k(f) represents the impedance frequency domain value calculated at frequency f; F(f) / represents the force value obtained by testing at frequency f.

[0050] The impedance frequency domain values ​​of k(f) corresponding to 1 to 3000 Hz (a total of 3,000 points) are summarized and plotted with frequency as the abscissa and impedance frequency domain values ​​as the ordinate to obtain the impedance frequency domain curve.

[0051] All vibration transmission points (including flexible bushing attachment points, bearing housing mounting points, and all cover plate geometric center points) must have their impedance frequency domain curves obtained using the steps described above. Specifically: impedance frequency domain curves in the X, Y, and Z directions need to be obtained for the flexible bushing attachment points; only the normal direction needs to be obtained for the bearing housing mounting points and all cover plate geometric center points. The impedance frequency domain curves for the flexible bushing attachment points, bearing housing mounting points, and cover plate geometric center points are shown below. Figures 1 to 3 As shown.

[0052] Calculation of the overall impedance coefficient at the flexible bushing attachment point:

[0053] Choose an impedance frequency domain curve corresponding to one direction of the flexible bushing attachment point. Calculate the slope of adjacent impedance frequency domain points spaced 1 Hz apart using the following formula:

[0054] kk(i~i+1)=k(i+1)-k(i)

[0055] In the formula, kk(i~i+1) represents the slope between the impedance frequency domain points between frequencies of i Hz and i+1 Hz. The frequency at which the slope first becomes negative is recorded; this frequency is defined as the cutoff frequency. If the slope is still not negative when the frequency reaches 1000 Hz, then 1000 Hz is defined as the cutoff frequency.

[0056] Find the minimum and second minimum impedance values ​​in the frequency domain within the cutoff frequency range of ~3000Hz, and record the corresponding frequencies and specific values, which are recorded here as: f min-1 f min-2 k min-1 k min-2 .

[0057] Step 3: Using f min-1 Find the impedance frequency domain value to both sides of the median value: 1.414 * f min-1 The two corresponding frequency points are recorded, and their frequency values ​​are recorded here as: f min-1-1 f min-1-2 The equivalent damping coefficient at the impedance minimum in the frequency domain is calculated using the following formula:

[0058] C min-1 =(f min-1-2 -f min-1-1 ) / 2 / f min-1

[0059] In the formula: C min-1 The equivalent damping coefficient at the impedance frequency domain minimum is given; the equivalent damping coefficient C at the impedance frequency domain second minimum is calculated using the same method. min-2 .

[0060] The impedance coefficient is calculated using the following formula:

[0061] ZK = 100 * (C min-1 +C min-2 )+0.01*(f min-1 +f min-2 )+1000*(1 / k min-1 +1 / k min-2 )

[0062] In the formula: ZK is the impedance coefficient of the flexible bushing attachment point. The impedance coefficients of all flexible bushing attachment points are calculated sequentially in the X, Y, and Z directions. The correlation coefficients calculated in this example are shown in Table 1:

[0063]

[0064] Table 1

[0065] The overall impedance coefficient of the flexible bushing attachment point is calculated based on the following formula:

[0066]

[0067] In the formula: ZZK is the comprehensive impedance coefficient of the flexible bushing attachment point; n represents the number of flexible bushing attachment points; ZK jx ZK represents the impedance coefficient in the X direction at the j-th flexible bushing attachment point. jy ZK represents the impedance coefficient in the Y direction at the j-th flexible bushing attachment point. jz This represents the impedance coefficient in the Z direction of the j-th flexible bushing attachment point. In this example, the calculated comprehensive impedance coefficient of the flexible bushing attachment point is 65.5.

[0068] Calculation of the overall impedance coefficient of the bearing housing mounting point:

[0069] First, using the same calculation method as the comprehensive impedance coefficient of the flexible bushing attachment point, obtain the cutoff frequency of the bearing housing mounting point. Within the cutoff frequency to 3000Hz range, find the minimum and second minimum impedance values ​​in the frequency domain, and record the corresponding frequencies and specific values. These are recorded here as: f min-1 f min-2 k min-1 k min-2 Find the maximum and second largest impedance values ​​in the frequency domain within the cutoff frequency to 3000Hz range, and record the corresponding frequencies and specific values. Here, they are recorded as: f max-1 f max-2 k max-1 k max-2 .

[0070] The impedance frequency domain average is calculated by averaging all impedance values ​​over the cutoff frequency to 3000Hz, and is recorded here as: k avg .

[0071] The impedance coefficient is calculated using the following formula:

[0072] YK = 1 / 30 * (100 * (k) max-1 / k min-1 +k max-2 / k min-2 )+50*(f max-1 / f min-1 +f max-2 / f min-2 )+k avg )

[0073] In the formula: YK is the impedance coefficient of the bearing housing mounting point. The correlation coefficients calculated in this example are shown in Table 2.

[0074] <![CDATA[f min-1 ]]> <![CDATA[f min-2 ]]> <![CDATA[f max-1 ]]> <![CDATA[f max-2 ]]> <![CDATA[k min-1 ]]> <![CDATA[k min-2 ]]> <![CDATA[k max-1 ]]> <![CDATA[k max-2 ]]> <![CDATA[k avg ]]> YK Point 1 1000Hz 2002Hz 1098Hz 2408Hz 53kN / mm 70kN / mm 402kN / mm 395kN / mm 134kN / mm 52.4 Point 2 1000Hz 1955Hz 2978Hz 2641Hz 64kN / mm 72kN / mm 441kN / mm 408kN / mm 117kN / mm 52.9 Point 3 477Hz 2311Hz 810Hz 2250Hz 9kN / mm 41kN / mm 998kN / mm 674kN / mm 412kN / mm 442.6

[0075] Table 2

[0076] The overall impedance coefficient of the bearing housing mounting point is calculated using the following formula:

[0077]

[0078] In the formula: YYK is the comprehensive impedance coefficient of the bearing housing mounting point; m represents the number of bearing housing mounting points; YK jl This represents the impedance coefficient in the normal direction of the j-th bearing housing mounting point. The calculated overall impedance coefficient of the bearing housing mounting point in this example is 182.7.

[0079] Calculation of the combined impedance coefficient at the geometric center point of the cover plate:

[0080] The cutoff frequency at the geometric center of the cover plate was obtained using the same calculation method as that used for the integrated impedance coefficient at the flexible bushing attachment point. The minimum and second minimum impedance values ​​in the frequency domain within the cutoff frequency range of 3000Hz were recorded, along with their corresponding frequencies and values. These are recorded here as: f min-1 f min-2 k min-1 k min-2 The equivalent damping coefficient at the minimum impedance value in the frequency domain and the equivalent damping coefficient at the second minimum impedance value in the frequency domain are recorded as: C min-1 C min-2 Find the maximum and second largest impedance values ​​in the frequency domain within the cutoff frequency to 3000Hz range, and record the corresponding frequencies and specific values. Here, they are recorded as: f max-1 f max-2 k max-1 k max-2 .

[0081] The calculation method obtains the average impedance in the frequency domain, which is recorded as: k avg .

[0082] The impedance coefficient at the geometric center point of the cover plate is calculated according to the following formula:

[0083] XK = 0.1 * (100 * (C min-1 +C min-2 )+0.001*(f min-1 +f min-2 )+10*(1 / k min-1 +1 / k min-2 )+10*(k max-1 / k min-1 +k max-2 / k min-2 )+10*(fmax-1 / f min-1 +f max-2 / f min-2 ) + k avg )

[0084] Where: XK is the impedance coefficient of the geometric center point of the cover plate. The relevant coefficients calculated in this example are shown in Table 3:

[0085]

[0086] Table 3

[0087] The comprehensive impedance coefficient of the geometric center point of the cover plate is calculated according to the following formula:

[0088]

[0089] Where: XXK is the comprehensive impedance coefficient of the geometric center point of the cover plate; s represents the number of bearing seat installation points; XK tl represents the impedance coefficient in the normal direction of the geometric center point of the t-th cover plate. The comprehensive impedance coefficient of the geometric center point of the cover plate calculated in this example is: 92.1.

[0090] Analysis of the impedance performance of the vibration transfer point of the electric drive assembly: According to the following formula, calculate the impedance coefficient of the vibration transfer point of the electric drive assembly:

[0091] SSK = ZZK + YYK + XXK

[0092] Where: SSK is the impedance coefficient of the vibration transfer point of the electric drive assembly. Finally, according to Table 4, score and rate the impedance performance of the vibration transfer point of the electric drive assembly. The impedance coefficient of the vibration transfer point of the electric drive assembly calculated in this example is: 340.3, and the final score of the impedance performance of the vibration transfer point of this electric drive assembly is: 5 points, and the grade is qualified.

[0093]

[0094] Table 4

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the technical solutions. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the purpose and scope of the technical solutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for analyzing the vibration transmission performance of an electric drive assembly in a new energy vehicle, characterized in that: include: (1) Excitation sources are arranged at multiple vibration transmission points of the electric drive assembly, and vibration acceleration signals and force sensing signals are collected synchronously. Vibration displacement is calculated based on vibration acceleration signals, and impedance frequency domain data of each vibration transmission point is generated by combining force sensing signals. Vibration transmission points include flexible connection points, rigid support points and cover plate geometric center points. (2) For flexible connection points: Determine the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency in the frequency band above the cutoff frequency, calculate the equivalent damping coefficient based on the impedance minimum value, combine the impedance minimum value and its corresponding frequency and the equivalent damping coefficient to calculate the single-point impedance coefficient, and calculate the comprehensive impedance coefficient of the flexible connection points by combining all flexible connection points. For rigid support points: Determine the cutoff frequency. In the frequency band above the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency and at least one impedance maximum value and its corresponding frequency. Calculate the average impedance in the frequency band above the cutoff frequency. Combine the impedance minimum value and its corresponding frequency, the impedance maximum value and its corresponding frequency, and the average impedance to calculate the single-point impedance coefficient. Integrate all rigid support points to calculate the comprehensive impedance coefficient of the rigid support points. For the geometric center point of the cover plate: determine the cutoff frequency, extract at least one impedance minimum value and its corresponding frequency and at least one impedance maximum value and its corresponding frequency in the frequency band above the cutoff frequency, calculate the equivalent damping coefficient based on the impedance minimum value, and calculate the average impedance in the frequency band above the cutoff frequency. Combine the impedance minimum value and its corresponding frequency, the equivalent damping coefficient and the average impedance to calculate the single-point impedance coefficient. Combine all the geometric center points of the cover plate to calculate the comprehensive impedance coefficient of the cover plate. (3) Add the comprehensive impedance coefficients of the flexible connection point, the rigid support point, and the cover plate to obtain the total impedance coefficient, and rate the vibration transmission performance of the electric drive assembly based on the total impedance coefficient.

2. The method for analyzing the vibration transmission performance of the electric drive assembly of a new energy vehicle according to claim 1, characterized in that: In step (1), the flexible connection point includes a flexible bushing attachment point, and the rigid support point includes a bearing housing mounting point.

3. The method for analyzing the vibration transmission performance of the electric drive assembly of a new energy vehicle according to claim 1, characterized in that: In step (1), the excitation source adopts the linear step sweep frequency method with equal time and equal amplitude.

4. The method for analyzing the vibration transmission performance of the electric drive assembly of a new energy vehicle according to claim 1, characterized in that: In step (2), when calculating the single-point impedance coefficient of the flexible connection point, the single-point unidirectional impedance coefficient of the flexible connection point is calculated sequentially in the X, Y, and Z directions, and the comprehensive impedance coefficient of the flexible connection point is calculated based on the formula: Where ZZK is the composite impedance coefficient of the flexible connection point, n is the number of flexible connection points, and ZK jx ZK represents the impedance coefficient in the X direction of the j-th flexible connection point. jy ZK represents the impedance coefficient in the Y direction of the j-th flexible connection point. jz This represents the impedance coefficient in the Z direction of the j-th flexible connection point.

5. The method for analyzing the vibration transmission performance of the electric drive assembly of a new energy vehicle according to claim 1, characterized in that: In step (2), the cutoff frequency is determined in the following way: based on the impedance frequency domain data, an impedance frequency domain curve is plotted with frequency as the abscissa and impedance frequency domain value as the ordinate, the impedance slope between adjacent frequency points is calculated, and the frequency corresponding to the first occurrence of a negative slope is taken as the cutoff frequency.

6. The method for analyzing the vibration transmission performance of the electric drive assembly of a new energy vehicle according to claim 5, characterized in that: Set a preset frequency. If no negative slope occurs within the preset frequency range, then set the preset frequency as the cutoff frequency.

7. The method for analyzing the vibration transmission performance of the electric drive assembly of a new energy vehicle according to claim 1, characterized in that: In step (3), a pre-defined rating and grading rule is set, and the rating is determined based on the calculated total impedance coefficient.

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