CN117057037A - Electric vehicle low-speed prompt tone simulation analysis method based on sound ray method - Google Patents

Abstract

The invention discloses an electric vehicle low-speed prompt tone simulation analysis method based on a sound ray method, which belongs to the technical field of automobiles and comprises the following steps of: modeling the cabin grid and the vehicle external field by adopting a sound ray method; setting excitation load and boundary conditions; calculating the frequency response of the response points, the sound pressure cloud image and the sound rays on the field point grids; optimizing the design; evaluating the calculation result and judging whether the expected effect is achieved; if the performance requirement of the low-speed prompt tone is not met, the calculation result is optimized by adjusting the position and angle of the speakers or adjusting the number of the speakers. The simulation analysis method adopts a sound ray method to carry out simulation analysis of the low-speed prompt audio response result of the electric vehicle, and is suitable for calculation of 20-20000Hz frequency band; in particular to a frequency response analysis method for calculating the corresponding position of a sound field transmitted from a cabin speaker sound source to the outside of a vehicle according to the actual installation situation of a speaker in a simcenter 3D environment.

Description

Electric vehicle low-speed prompt tone simulation analysis method based on sound ray method

Technical Field

The invention belongs to the technical field of automobiles, and particularly relates to a sound ray method-based simulation analysis method for low-speed prompt sounds of an electric vehicle.

Background

The low-speed prompting sound of the electric vehicle is generated by a loudspeaker arranged at the front and rear of the vehicle, so that surrounding pedestrians can be prompted in the low-speed running process of the electric vehicle, and the low-speed prompting sound of the electric vehicle is a national mandatory regulation item. In the low-speed prompt tone design and development process, the test sample car or mule car is usually required to be evaluated in a real car test mode. The failure to evaluate performance in the initial stage of design causes a risk of long development cycle and high design change cost. And the performance of the low-speed prompt tone is calculated by adopting a simulation analysis method, and the risk assessment is carried out before the test-run off-line, so that the development period can be effectively shortened, and the development cost can be reduced.

As a result of the need to simulate the frequency response of the speakers from the front cabin to the outside of the vehicle. The existing simulation method such as finite element method can not completely meet the requirements. The use of the finite element method requires the building of a structural finite element model of the relevant structure in the nacelle, and additionally requires the building of a fluid finite element model of the entity with air of the propagation path inside and outside the nacelle. Therefore, the whole model node has more degrees of freedom and huge calculation amount. Meanwhile, as the hearing frequency range of the human ear is 20-20000Hz, the finite element method is adopted for the wide frequency range, the finite element grid size is required to be very small to meet the precision requirement, the requirement on the computing resource is very high, and the computing efficiency is also very low.

Disclosure of Invention

Aiming at the problems of huge calculated amount and the like in the simulation method in the prior art, the invention provides a simulation analysis method of the low-speed prompt tone of the electric vehicle based on a sound ray method, which adopts the sound ray method to carry out simulation analysis of the low-speed prompt tone response result of the electric vehicle and is suitable for calculation of a frequency band of 20-20000 Hz; in particular to a frequency response analysis method for calculating the corresponding position of a sound field transmitted from a cabin speaker sound source to the outside of a vehicle according to the actual installation situation of a speaker in a simcenter 3D environment.

The invention is realized by the following technical scheme:

the simulation analysis method for the low-speed prompt tone of the electric vehicle based on the sound ray method specifically comprises the following steps:

s1, modeling a cabin grid and an external sound field by adopting a sound ray method, and respectively applying boundary conditions;

s2, setting a plurality of excitation points according to the number and positions of the loudspeakers, and respectively performing a frequency response test and a directivity test on the plurality of excitation points under white noise excitation after setting response point positions and low-speed prompt sound field simulation analysis working conditions;

s3, respectively calculating the frequency response test data and the directivity test data obtained in the step S2, and obtaining a sound field cloud image and sound rays;

s4, evaluating the calculation result in the step S3, and judging whether the expected effect is achieved; if the performance requirement of the low-speed prompt tone is not met, the calculation result is optimized by adjusting the position and angle of the speakers or adjusting the number of the speakers.

Further, in step S1, cabin grid modeling specifically includes the following:

the cabin grid comprises a power assembly grid, a cooling fan grid, a suspension grid and an outer decoration guard plate grid; the cabin grids are all 2-dimensional models, and the size of the grids is 5mm-10mm.

Further, the mass of the power assembly grid, the cooling fan grid, the suspension grid and the outer decoration guard plate grid follow the following principle:

A. the quadrangle unit QUAD is more than 95%, and the triangle unit TRIA is less than 5%;

B. the minimum size of the unit is 3mm, the maximum size is 5mm, and the average size is 4mm;

C. 95% of units are warp < 7deg, and all units are warp < 10deg;

D. 95% of the units are less than 5, and all the units are less than 7;

E. 95% of unit skew < 30deg, and all unit skew < 40deg;

F. 95% of units jacobian < 0.7, and all units jacobian < 0.3;

G. 95% of units per are less than 0.7, and all units per are less than 0.8;

H、inner angle:quads min angle＞45deg，max angle＜135deg，trias min angle＞30deg，max angle＜120deg。

further, in step S1, the modeling of the sound field outside the vehicle specifically includes the following:

the external sound field of the vehicle adopts a 2-dimensional plane quadrilateral grid, the size of the grid is 10mm-50mm, and the size of the grid can be adjusted according to the point positions of the response points, and the X-Y plane where the response points are located is used as a plane field point.

Further, in step S1, the position of the cabin sound absorbing material is applied with a sound absorption coefficient; the edges of the locomotion assembly grid and suspension grid impose diffraction boundary conditions.

Further, in step S2, the frequency response test is a frequency response curve obtained by the plurality of excitation points at a position 1m in front of the speaker unit under white noise excitation, and the frequency interval is equal to 10Hz.

Further, in step S2, the directivity test is as follows: and arranging a loudspeaker on a plane baffle in a full-silencing room, arranging a microphone on an annular bracket, adjusting the angle between the microphone and the front face of the loudspeaker, and testing to obtain sound pressure of each position and angle, thereby obtaining directivity data.

Further, the distance between the annular bracket and the loudspeaker is 0.5m, 1m, 1.5m and 2m; the angle includes 0 °, 30 °, 45 °, 60 °, 90 °.

Further, in step S2, the low-speed alert sound field simulation analysis conditions are set as follows:

A. the frequency response analysis frequency band is 20 Hz-20000 Hz,1/3 octave;

B. the upper limit of the structural mode and the acoustic cavity mode analysis frequency is 2 times of the upper limit of the frequency response analysis frequency;

C. the maximum number of reflections of sound rays is set to 4 and the maximum path is set to 3 meters.

Compared with the prior art, the invention has the following advantages:

(1) Compared with the finite element method, the sound ray method does not need to use a large number of entity grids, and the calculation speed is greatly improved;

(2) The sound ray method has traceability, is particularly suitable for intuitively tracking the transmission path from the sound source to the response position, so that scheme optimization is better carried out;

(3) By adopting the simulation analysis method, the simulation precision can be improved, the design efficiency can be improved, and the development cost related to low-speed prompt tones can be reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.

FIG. 1 is a flow chart of a simulation analysis method of low-speed prompt tones of an electric vehicle based on a sound ray method;

fig. 2 is a schematic diagram of a loudspeaker sound source directivity test;

FIG. 3 is a schematic diagram of simulated constant velocity test response points;

FIG. 4 is a schematic diagram of simulated reverse test response points;

FIG. 5 is a schematic diagram of a sound ray method model of the whole vehicle;

FIG. 6 is a schematic diagram of speaker position;

FIG. 7 is a diagram showing the simulation result of low-speed cue audio response;

FIG. 8 is a cloud image of a departure point for a certain frequency;

FIG. 9 is a schematic diagram of a low-speed alert tone speaker at a certain frequency to an off-board left station sound line;

FIG. 10 is a schematic diagram of a modification of speaker position;

FIG. 11 is a graph showing the comparison of the optimized frequency response results.

Detailed Description

For a clear and complete description of the technical scheme and the specific working process thereof, the following specific embodiments of the invention are provided with reference to the accompanying drawings in the specification:

in the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

Example 1

The embodiment provides a simulation analysis method of low-speed prompt tones of an electric vehicle based on a sound ray method, which is characterized in that white noise excitation is applied to the position of a cabin loudspeaker, the frequency response at a measuring point outside the vehicle is analyzed, the sound ray transmission paths from each frequency to the response position are found for the excitation of a single loudspeaker, the sound pressure cloud images at each frequency can be obtained on the field point outside the vehicle, and the position of the loudspeaker can be optimized according to the simulation result;

as shown in fig. 1, the method specifically comprises the following steps:

s1, modeling a cabin grid and an external sound field by adopting a sound ray method, and respectively applying boundary conditions;

s2, setting a plurality of excitation points according to the number and positions of the loudspeakers, and respectively performing a frequency response test and a directivity test on the plurality of excitation points under white noise excitation after setting response point positions and low-speed prompt sound field simulation analysis working conditions;

s3, respectively calculating the frequency response test data and the directivity test data obtained in the step S2, and obtaining a sound field cloud image and sound rays;

s4, evaluating the calculation result in the step S3, and judging whether the expected effect is achieved; if the performance requirement of the low-speed prompt tone is not met, the calculation result is optimized by adjusting the position and angle of the speakers or adjusting the number of the speakers.

In this embodiment, the cabin grid modeling in step S1 specifically includes the following:

the cabin grid comprises a power assembly grid, a cooling fan grid, a suspension grid and an outer decoration guard plate grid; the cabin grids are all 2-dimensional models, and the size of the grids is 5mm-10mm.

In this embodiment, the mass of the power assembly grid, the cooling fan grid, the suspension grid, and the trim cover grid follow the following principle:

A. the quadrangle unit QUAD is more than 95%, and the triangle unit TRIA is less than 5%;

B. the minimum size of the unit is 3mm, the maximum size is 5mm, and the average size is 4mm;

C. 95% of units are warp < 7deg, and all units are warp < 10deg;

D. 95% of the units are less than 5, and all the units are less than 7;

E. 95% of unit skew < 30deg, and all unit skew < 40deg;

F. 95% of units jacobian < 0.7, and all units jacobian < 0.3;

G. 95% of units per are less than 0.7, and all units per are less than 0.8;

H、inner angle:quads min angle＞45deg，max angle＜135deg，trias min angle＞30deg，max angle＜120deg。

in this embodiment, in step S1, the modeling of the sound field outside the vehicle specifically includes the following:

the external sound field of the vehicle adopts a 2-dimensional plane quadrilateral grid, the size of the grid is 10mm-50mm, and the size of the grid can be adjusted according to the point positions of the response points, and the X-Y plane where the response points are located is used as a plane field point.

In the present embodiment, in step S1, the position of the cabin sound absorbing material is applied with a sound absorption coefficient; the edges of the locomotion assembly grid and suspension grid impose diffraction boundary conditions.

In this embodiment, in step S2, the frequency response test is a frequency response curve obtained by a plurality of excitation points at a position 1m in front of the speaker unit under white noise excitation, and the frequency interval is equal to 10Hz.

In this embodiment, in step S2, the directivity test is as follows: and arranging a loudspeaker on a plane baffle in a full-silencing room, arranging a microphone on an annular bracket, adjusting the angle between the microphone and the front face of the loudspeaker, and testing to obtain sound pressure of each position and angle, thereby obtaining directivity data.

In the embodiment, the distance between the annular bracket and the loudspeaker is 0.5m, 1m, 1.5m and 2m; the angle includes 0 °, 30 °, 45 °, 60 °, 90 °.

In this embodiment, in step S2, the low-speed alert sound field simulation analysis conditions are set as follows:

A. the frequency response analysis frequency band is 20 Hz-20000 Hz,1/3 octave;

B. the upper limit of the structural mode and the acoustic cavity mode analysis frequency is 2 times of the upper limit of the frequency response analysis frequency;

C. the maximum number of reflections of sound rays is set to 4 and the maximum path is set to 3 meters.

Example 2

The embodiment provides an electric vehicle low-speed prompt tone simulation analysis method based on a sound ray method, which specifically comprises the following steps:

modeling by Step acoustic line method;

step 1.1, modeling cabin grids;

the cabin grid is required to be input into surface grids such as a cabin body structure, a power assembly, an outer decoration guard plate, a suspension and the like. The grid adopts a 2-dimensional model, the size of the grid is 5mm-10mm, and the quality of the grid is controlled as follows:

a) The quadrangle unit QUAD is more than 95%, and the triangle unit TRIA is less than 5%;

b) The unit size is minimum 3mm, maximum 5mm and average 4mm;

c) 95% of units are warp < 7deg, and all units are warp < 10deg;

d) 95% of the units are less than 5, and all the units are less than 7;

e) 95% of unit skew < 30deg, and all unit skew < 40deg;

f) 95% of units jacobian < 0.7, and all units jacobian < 0.3;

g) 95% of units per are less than 0.7, and all units per are less than 0.8;

h)inner angle:quads min angle＞45deg，max angle＜135deg，trias min angle＞30deg，max angle＜120deg。

step 1.2 modeling of the outer field point of the vehicle;

the acoustic cavity field point adopts a 2-dimensional plane quadrilateral grid, the size of the grid is 10mm-50mm, the size of the grid can be adjusted according to the response point position, and the X-Y plane where the response point is positioned is generally used as the plane field point.

Step 2, setting excitation load and boundary conditions;

step 2.1 excitation loading;

the excitation point is positioned at the center of the low-speed prompt tone loudspeaker unit model in the cabin, and the direction is the +Z direction of the actual arrangement position. The excitation data is a frequency response curve of the position, 1m, right in front of the loudspeaker unit under white noise excitation, and the frequency interval is equal to 10Hz. The excitation is to contain directivity data.

The directivity information of the sound source of the loudspeaker is the attenuation coefficient of sound waves emitted by the loudspeaker along with the change of the spatial position and the angle, and the attenuation coefficient needs to be measured through experiments. The loudspeakers are arranged on a planar baffle in a fully anechoic chamber, the microphones are arranged on a ring-shaped support, which is 0.5m, 1m, 1.5m, 2m from the loudspeakers. The angles of the microphone and the front face of the loudspeaker are adjusted, generally, the angles of 0 degree, 30 degrees, 45 degrees, 60 degrees, 90 degrees and the like are at least included, sound pressures of all positions and angles are obtained through testing, and then sound source directivity data are calculated. Fig. 2 is a schematic diagram of a loudspeaker sound source directivity test.

Step 2.2 boundary Condition

And the loudspeaker models x, y and z are constrained, and the surface of the engine room model is loaded with acoustic impedance coefficients and sound absorption coefficients according to the sound absorption materials. Smooth surfaces such as locomotion assemblies, suspensions, etc. locally require increased diffraction boundary conditions.

Step 3 response calculation

Step 3.1 response Point parameter setting

The response point takes the following four positions:

the coordinates (x, y, z) of the forward operating condition response point P, P' are shown in table 3;

TABLE 3 Table 3

x	Vehicle front-most y-z plane x coordinate
		y	±(2.0m±0.05m)
z	1.2m±0.02m

The coordinates (x, y, z) of the reverse operating condition response point P, P' are shown in table 4;

TABLE 4 Table 4

x	Vehicle rearmost y-z plane x coordinate
		y	±(2.0m±0.05m)
z	1.2m±0.02m

Step 3.2 response analysis parameter set

The simulation analysis working conditions of the low-speed prompt sound field are set as follows:

the frequency response analysis frequency band is 20 Hz-20000 Hz,1/3 octave.

The structural mode and the acoustic cavity mode analysis frequency upper limit is 2 times that of the frequency response analysis frequency upper limit.

The maximum number of reflections of sound rays is set to 4 and the maximum path is set to 3 meters.

Step 3.3 frequency response calculation

The frequency response at the response point under white noise excitation is calculated.

Step 3.4 Sound field cloud image calculation

And calculating a sound pressure cloud picture of the low-speed prompt tone on the field point grid according to the modeling of the pre-set vehicle exterior field point.

Step 3.5 sound ray calculation

Sound rays propagating from the sound source to the off-vehicle response point at each frequency are calculated.

Step 4, optimizing design;

and judging whether the expected effect is achieved or not through evaluation of the frequency response calculation result. If the performance requirement of the low-speed prompt tone is not met, the calculation result can be optimized by adjusting the position and angle of the speakers or adjusting the number of the speakers.

Example 3

The embodiment provides an electric vehicle low-speed prompt tone simulation analysis method based on a sound ray method, which specifically comprises the following steps:

s1, modeling a cabin grid and an automobile external field by adopting a sound ray method;

as shown in fig. 5, a sound ray method model of a certain vehicle model is built in the present embodiment;

s2, setting excitation load and boundary conditions;

s21, setting excitation points according to the number and the positions of the real vehicle loudspeakers, as shown in FIG. 6;

s22, applying boundary conditions to the model. The cabin sound absorbing material or the like applies a sound absorption coefficient. At the same time, the power assembly, suspension grid edges, etc. impose diffraction boundary conditions.

The complex impedance is obtained by acoustic impedance tube testing.

The obtained frequency-dependent parameters of the impedance of the different regions are shown in Table 1 below

TABLE 1

Frequency of	Real part of impedance	Imaginary part of impedance
			100	-0.81	-6.56
125	0.52	-7.36
			160	1.24	-7.02
200	1.30	-6.32
			250	1.18	-5.29
315	1.07	-4.18
			400	1.05	-3.16
500	1.04	-2.20
			630	1.32	-1.37
800	1.83	-0.61
			1000	2.52	-0.09
1250	3.18	0.18
			1600	4.06	1.50
2000	5.95	0.00
			2500	4.26	-2.07
3150	2.97	-0.86
			4000	3.51	-0.55
5000	3.25	-0.92
			6300	3.52	-0.59

Acoustic impedance tube test for sound absorption coefficient or reverberant room acquisition

The obtained parameters of the sound absorption coefficient of different areas along with the frequency are referred to in the following table 2

TABLE 2

Frequency of	Coefficient of sound absorption
		250	0.15
315	0.18
		400	0.58
500	0.47
		630	0.34
800	0.55
		1000	0.40
1250	0.45
		1600	0.42
2000	0.42
		2500	0.47
3150	0.50
		4000	0.48
5000	0.40
		6300	0.58
8000	0.56

S3, calculating the frequency response of the response points, the sound pressure cloud image and the sound rays on the field point grids;

s4, optimizing design;

evaluating the calculation result in the step S3, wherein the total sound level of 10km/h at a constant speed forward running should not be lower than 52dB (A), and the total sound level of 20km/h at a constant speed forward running should not be lower than 58dB (A) according to the requirements of national standard GB/T37153-2018 electric automobile low-speed prompt tones; judging whether the expected effect is achieved according to the standard; if the performance requirement of the low-speed prompt tone is not met, the calculation result is optimized by adjusting the position and angle of the speakers or adjusting the number of the speakers.

Specifically, the position of the loudspeaker and the direction of the loudspeaker can be changed to be downward, as shown in fig. 10, so that the sound pressure level of the measuring point position can be ensured to reach the national standard, as shown in fig. 11.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.

In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.

Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.

Claims (9)

1. The simulation analysis method for the low-speed prompt tone of the electric vehicle based on the sound ray method is characterized by comprising the following steps of:

s1, modeling a cabin grid and an external sound field by adopting a sound ray method, and respectively applying boundary conditions;

s2, setting a plurality of excitation points according to the number and positions of the loudspeakers, and respectively performing a frequency response test and a directivity test on the plurality of excitation points under white noise excitation after setting response point positions and low-speed prompt sound field simulation analysis working conditions;

s3, respectively calculating the frequency response test data and the directivity test data obtained in the step S2, and obtaining a sound field cloud image and sound rays;

s4, evaluating the calculation result in the step S3, and judging whether the expected effect is achieved; if the performance requirement of the low-speed prompt tone is not met, the calculation result is optimized by adjusting the position and angle of the speakers or adjusting the number of the speakers.

2. The method for simulating and analyzing the low-speed prompt tone of the electric vehicle based on the sound ray method as claimed in claim 1, wherein the cabin grid modeling in the step S1 specifically comprises the following steps:

the cabin grid comprises a power assembly grid, a cooling fan grid, a suspension grid and an outer decoration guard plate grid; the cabin grids are all 2-dimensional models, and the size of the grids is 5mm-10mm.

3. The sound ray method-based simulation analysis method for low-speed prompt sounds of electric vehicles according to claim 2, wherein the mass of the power assembly grid, the cooling fan grid, the suspension grid and the exterior guard plate grid follow the following principles:

A. the quadrangle unit QUAD is more than 95%, and the triangle unit TRIA is less than 5%;

B. the minimum size of the unit is 3mm, the maximum size is 5mm, and the average size is 4mm;

C. 95% of units are warp < 7deg, and all units are warp < 10deg;

D. 95% of the units are less than 5, and all the units are less than 7;

E. 95% of unit skew < 30deg, and all unit skew < 40deg;

F. 95% of units jacobian < 0.7, and all units jacobian < 0.3;

G. 95% of units per are less than 0.7, and all units per are less than 0.8;

H、inner angle:quads min angle＞45deg，max angle＜135deg，trias min angle＞30deg，max angle＜120deg。

4. the method for simulating and analyzing the low-speed prompt tone of the electric vehicle based on the sound ray method as claimed in claim 1, wherein the modeling of the sound field outside the vehicle in the step S1 specifically comprises the following steps:

the external sound field of the vehicle adopts a 2-dimensional plane quadrilateral grid, the size of the grid is 10mm-50mm, and the size of the grid can be adjusted according to the point positions of the response points, and the X-Y plane where the response points are located is used as a plane field point.

5. The sound ray method-based simulation analysis method for low-speed warning sounds of electric vehicles according to claim 1, wherein in step S1, the sound absorption coefficient is applied to the position of the cabin sound absorption material; the edges of the locomotion assembly grid and suspension grid impose diffraction boundary conditions.

6. The simulation analysis method of low-speed prompt tone of electric vehicle based on sound ray method as claimed in claim 1, wherein in step S2, the frequency response test is a frequency response curve obtained by a plurality of excitation points at a position 1m in front of a speaker unit under white noise excitation, and the frequency interval is equal to 10Hz.

7. The method for simulating and analyzing the low-speed prompt tone of the electric vehicle based on the sound ray method as claimed in claim 1, wherein in the step S2, the directivity test is as follows: and arranging a loudspeaker on a plane baffle in a full-silencing room, arranging a microphone on an annular bracket, adjusting the angle between the microphone and the front face of the loudspeaker, and testing to obtain sound pressure of each position and angle, thereby obtaining directivity data.

8. The sound ray method-based simulation analysis method for low-speed prompt sounds of an electric vehicle according to claim 7, wherein the distance between the annular bracket and the loudspeaker is 0.5m, 1m, 1.5m and 2m; the angle includes 0 °, 30 °, 45 °, 60 °, 90 °.

9. The sound ray method-based simulation analysis method for low-speed prompt sound of an electric vehicle as claimed in claim 1, wherein in step S2, the simulation analysis conditions of the sound field of the low-speed prompt sound are set as follows:

A. the frequency response analysis frequency band is 20 Hz-20000 Hz,1/3 octave;

B. the upper limit of the structural mode and the acoustic cavity mode analysis frequency is 2 times of the upper limit of the frequency response analysis frequency;

C. the maximum number of reflections of sound rays is set to 4 and the maximum path is set to 3 meters.