Dynamic stiffness performance analysis method for vehicle all-in-one motor assembly

Abstract

The invention discloses a dynamic stiffness performance analysis method for an all-in-one motor assembly for a vehicle, sub-components of the all-in-one motor assembly comprise a controller upper cover plate, a controller lower cover plate and a rotary transformer cover plate, and the method comprises the following steps: 1) carrying out frequency domain response tests on the sub-components of the all-in-one motor assembly; 2) modal frequency identification of each sub-component of the all-in-one motor assembly; 3) performing frequency domain response test on each suspension mounting point of the all-in-one motor assembly; 4) calculating the dynamic stiffness of each suspension mounting point of the all-in-one motor assembly; 5) performing a frequency domain response test of the all-in-one motor assembly; 6) identifying the modal frequency of the all-in-one motor assembly; and 7) calculating and analyzing the rigidity performance of the all-in-one motor assembly. According to the invention, rapid iteration of the all-in-one motor assembly can be realized on the premise of no rack and whole vehicle resource support; the purposes of shortening the development period, recognizing risk problems in advance and saving the test cost of the whole vehicle are achieved.

Description

Technical Field

[0001] The present invention relates to the field of new energy vehicle electric drive technology, and in particular to a method for analyzing dynamic stiffness performance of an all-in-one motor assembly for a vehicle. Background Art

[0002] The all-in-one motor assembly on new energy vehicles generally refers to the technology that integrates key components such as the drive motor, controller, and reducer into one module. This integrated design helps to reduce the size of the power system, reduce the weight of the vehicle, reduce manufacturing costs, and improve the energy efficiency of the vehicle.

[0003] The all-in-one motor assembly is one of the key technologies of the powertrain system of new energy vehicles, and its development is the general trend of the industry. The integration of this system not only reduces costs, but also improves the product cost performance. At present, there are many integrated forms from three-in-one to ten-in-one on the market, among which the most common is the three-in-one electric drive system.

[0004] The technical advantages of the all-in-one motor assembly include smaller size, lighter weight, more efficient power and lower cost, which can improve the power performance and range of the entire vehicle.

[0005] As one of the key components of the powertrain of new energy vehicles, the overall stiffness performance of the all-in-one motor assembly directly affects the vibration and noise performance of the drive motor itself. Therefore, how to ensure that its ability to suppress vibration and noise can be effectively evaluated without the need for vehicle test resources, thereby providing an important basis for product optimization, shortening the development cycle, identifying risk issues in advance, and saving vehicle test costs has become a technical problem that technicians in this field need to solve urgently. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a method for dynamic stiffness performance analysis of an automotive all-in-one motor assembly that can effectively evaluate its own ability to suppress vibration and noise without the need for vehicle testing resources, thereby providing an important basis for product optimization, shortening the development cycle, identifying risk issues in advance, and saving vehicle testing costs.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A method for analyzing dynamic stiffness performance of an all-in-one motor assembly for a vehicle, wherein the subcomponents of the all-in-one motor assembly include a controller upper cover, a controller lower cover, and a resolver cover. The method includes the following steps:

[0009] Step 1) performing a frequency domain response test of each subcomponent of the all-in-one motor assembly;

[0010] Step 2) identifying the modal frequencies of each subcomponent of the all-in-one motor assembly;

[0011] Step 3) performing a frequency domain response test of each mounting point of the all-in-one motor assembly;

[0012] Step 4) Calculate the dynamic stiffness of each mounting point of the all-in-one motor assembly;

[0013] Step 5) performing a frequency domain response test of the all-in-one motor assembly;

[0014] Step 6) Modal frequency identification of the all-in-one motor assembly;

[0015] Step 7) Calculation and analysis of the dynamic stiffness performance of the all-in-one motor assembly.

[0016] Preferably, step 1) includes the following steps:

[0017] Step 1.1) a first vibration acceleration sensor is arranged at the geometric center point of each subcomponent of the all-in-one motor assembly, and then a plurality of first excitation points are evenly arranged on a circle with the first vibration acceleration sensor as the center and the first set value as the radius, and a pulse normal excitation is applied at each first excitation point using a force hammer, and the vibration acceleration signal of the first acceleration sensor position of each subcomponent and the force signal at the first excitation point are recorded;

[0018] Step 1.2) Perform Fourier calculation on the vibration acceleration signal and force signal obtained in step 1.1) so that each signal is decomposed in the frequency domain;

[0019] Step 1.3) Divide the decomposed vibration acceleration signal and the force signal point by point to obtain a frequency domain response function;

[0020] Step 1.4) Calculate the average value of multiple frequency domain response functions of the vibration acceleration signal and force signal in the frequency domain with a frequency interval of 1 Hz to obtain the final frequency domain response curve. The average value calculation formula is:

[0021]

[0022] Where: H i (ω) is the frequency response value of the ith subcomponent at frequency ω; a i (ω) is the vibration acceleration value of the ith subcomponent at frequency ω, F i (ω) is the excitation load value of the i-th subcomponent at frequency ω.

[0023] Preferably, in step 2), according to the frequency domain response curve of each subcomponent obtained in step 1), 50-order function, 100-order function and 150-order function are respectively used for fitting, and all roots on the denominator of 50-order function, 100-order function and 150-order function are respectively calculated, all roots are respectively fitted with 50-order function, 100-order function and 150-order function, and the minimum value of all roots is found, the minimum value of all roots of the controller upper cover plate is used as the first-order modal frequency of the controller upper cover plate, the minimum value of all roots of the controller lower cover plate is used as the first-order modal frequency of the controller lower cover plate, and the minimum value of all roots of the resolver cover plate is used as the first-order modal frequency of the resolver cover plate.

[0024] Preferably, step 3) includes the following steps:

[0025] Step 3.1) Arrange a second vibration acceleration sensor at the middle diameter of the boss ring of each suspension mounting point of the all-in-one motor assembly;

[0026] Step 3.2) The counterpoint position of each second vibration acceleration sensor is used as the second excitation point, and a pulse normal excitation is applied at each second excitation point using a force hammer, and each second excitation point is excited in three directions of X, Y, and Z, and the vibration acceleration signal of each second vibration acceleration sensor position and the force signal at each second excitation point are recorded;

[0027] Step 3.3) performing Fourier decomposition on the vibration acceleration signal and force signal obtained in step 3.2), dividing the decomposed force signal point by point to obtain a frequency domain response function;

[0028] Step 3.4) Obtain the final frequency domain response curve according to the following formula;

[0029]

[0030] Where: H j (ω) is the frequency response value of the jth suspension installation point at the frequency ω; a j (ω) is the vibration acceleration value of the jth suspension installation point at the frequency ω, F j (ω) is the excitation load value of the jth suspension installation point at the frequency ω.

[0031] Preferably, in step 4), the formula for calculating the dynamic stiffness curve based on the frequency domain response curve obtained in step 3) is:

[0032]

[0033] Where: K j (ω) is the dynamic stiffness value of the jth suspension installation point at the frequency ω, H j(ω) is the frequency response value of the jth suspension installation point at the frequency ω.

[0034] Preferably, step 5) includes the following steps:

[0035] Step 5.1) Arrange multiple third vibration acceleration sensors on both side end surfaces and the middle interface of the all-in-one motor assembly, hit the bottom center point of the middle interface of the all-in-one motor assembly with a hammer, and record the vibration acceleration signals of each third vibration acceleration sensor and the force signal of the bottom center point of the middle interface of the all-in-one motor assembly;

[0036] Step 5.2) Perform Fourier calculation on the vibration acceleration signal and force signal obtained in step 5.1) so that each signal is decomposed in the frequency domain;

[0037] Step 5.3) Divide the decomposed vibration acceleration signal and the force signal point by point to obtain a frequency domain response function;

[0038] Step 5.4) Calculate the average value of multiple frequency domain response functions of the vibration acceleration signal and force signal in the frequency domain with a frequency interval of 1 Hz to obtain the final frequency domain response curve. The average value calculation formula is:

[0039]

[0040] Where: H r (ω) is the frequency response value of the installation point of the rth third vibration acceleration sensor when the frequency is ω; a r (ω) is the vibration acceleration value of the installation point of the rth third vibration acceleration sensor at the frequency ω, F r (ω) is the excitation load value of the installation point of the rth third vibration acceleration sensor at the frequency of ω;

[0041] Step 5.5) uses the following formula to synthesize all the frequency domain response curves in step 5.4):

[0042]

[0043] Wherein: Hr(ω) is the frequency response value of the rth third vibration acceleration sensor installation point when the frequency is ω, and Hsum(ω) is the composite value of the frequency response of all third acceleration sensor installation points when the frequency is ω.

[0044] Preferably, in step 6), according to the frequency domain response curves of each third vibration acceleration sensor installation point obtained in step 5), 50-order functions, 100-order functions and 150-order functions are used for fitting, and all roots on the denominator of the 50-order function, 100-order function and 150-order function are calculated respectively, the roots obtained by the three fittings are found to have the same value and are summarized, and the values ​​of the first 4 smallest roots are recorded and recorded as the first, second, third and fourth modal frequencies of the all-in-one motor assembly respectively.

[0045] Preferably, step 7) includes the following steps:

[0046] Step 7.1) Calculate the total modal value of the all-in-one motor assembly according to the following formula;

[0047]

[0048] Wherein: U1 is the first-order modal frequency of the upper cover of the controller, L1 is the first-order modal frequency of the lower cover of the controller, T1 is the first-order modal frequency of the resolver cover, E1 is the first-order modal frequency of the all-in-one motor assembly, E2 is the second-order modal frequency of the all-in-one motor assembly, E3 is the third-order modal frequency of the all-in-one motor assembly, and E4 is the fourth-order modal frequency of the all-in-one motor assembly;

[0049] Step 7.2) Calculate the total value of the dynamic stiffness of each suspension installation point according to the following formula;

[0050]

[0051] Where: KK is the total value of the dynamic stiffness of each suspension installation point;

[0052] Step 7.3) Calculate the stiffness performance coefficient of the all-in-one motor assembly according to the following formula:

[0053] PerFFre+KK

[0054] Where: Per is the stiffness performance coefficient of the all-in-one motor assembly;

[0055] Step 7.4) Evaluate the stiffness performance of the all-in-one motor assembly based on the stiffness performance coefficient of the all-in-one motor assembly.

[0056] Compared with the prior art, the present invention has the following advantages:

[0057] 1. The present invention provides a method for quantifying the stiffness characteristics of an all-in-one motor assembly, which can quickly and effectively evaluate the product performance of the all-in-one motor assembly.

[0058] 2. The present invention realizes the target positioning in the early stage of the development of the all-in-one motor assembly product, providing an important basis for product optimization.

[0059] 3. The present invention can realize the rapid iteration of the all-in-one motor assembly without the support of test bench and vehicle resources, thereby shortening the development cycle, identifying risk issues in advance, and saving vehicle testing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a structural schematic diagram of one viewing angle of the all-in-one motor assembly in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0061] Figure 2 It is a structural schematic diagram of another perspective of the all-in-one motor assembly in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0062] Figure 3 It is a schematic diagram of the excitation of the upper cover plate of the controller in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0063] Figure 4 It is a schematic diagram of the excitation of the lower cover of the controller in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0064] Figure 5 It is a schematic diagram of the excitation of the rotary transformer cover plate in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0065] Figure 6 It is a final frequency response curve diagram of each sub-component in the dynamic stiffness performance analysis method of the vehicle all-in-one motor assembly of the present invention;

[0066] Figure 7 It is a schematic diagram of the excitation of each suspension installation point in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0067] Figure 8 It is a frequency response curve diagram of each suspension installation point in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0068] Fig. 9 It is a dynamic stiffness calculation curve diagram of each suspension installation point in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0069] Fig.10 It is a schematic diagram of the excitation of the all-in-one motor assembly in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention;

[0070] Fig.11 It is a frequency response composite value curve diagram of the all-in-one motor assembly in the dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle of the present invention.

[0071] Explanation of the accompanying drawings: controller upper cover 1, controller lower cover 2, resolver cover 3, suspension mounting point 4, first vibration acceleration sensor 5, first excitation point 6, second vibration acceleration sensor 7, second excitation point 8, third vibration acceleration sensor 9, third excitation point 10. DETAILED DESCRIPTION

[0072] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0073] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0074] This solution provides a method for analyzing the dynamic stiffness performance of an all-in-one motor assembly for a vehicle. Figure 1 and attached Figure 2 As shown, the all-in-one motor assembly generally refers to a technology that integrates key components such as a drive motor, a controller, and a reducer into one module. A rotary encoder (referred to as a resolver) is provided on the drive motor. The rotary encoder is installed on the drive motor through a resolver cover 3 to collect the rotation signal of the drive motor and output it to the controller. The controller includes a controller upper cover 1 and a controller lower cover 2. The subcomponents studied in this solution for the all-in-one motor assembly mainly include a controller upper cover 1, a controller lower cover 2, and a resolver cover 3. The method includes the following steps:

[0075] Step 1) Conduct frequency domain response tests on each subcomponent of the all-in-one motor assembly.

[0076] Step 1.1) The first vibration acceleration sensor 5 is arranged at the geometric center point of each sub-component of the all-in-one motor assembly, that is, the first vibration acceleration sensor 5 is arranged at the geometric center point of the controller upper cover plate 1, the controller lower cover plate 2 and the resolver cover plate 3, for collecting the vibration acceleration signal; then, with the first vibration acceleration sensor 5 as the center, the first set value is on the circumference of the radius, in this specific embodiment, the first set value is 3mm, and a plurality of first excitation points 6 are evenly arranged. In this specific embodiment, four first excitation points 6 are arranged at intervals of 90°, and a pulse normal excitation is applied at each first excitation point 6 using a force hammer, and the vibration acceleration signal of the vibration first acceleration sensor position of each sub-component and the force signal at the first excitation point 6 are recorded, and the force signal is collected using a force sensor; in this way, the controller upper cover plate 1, the controller lower cover plate 2 and the resolver cover plate 3 will each have 4 force signals and 1 vibration acceleration signal, specifically, the arrangement position of the first vibration acceleration sensor 5 on the controller upper cover plate 1 and the position of the first excitation point 6 of the force hammer are shown in the attached Figure 3 For the arrangement position of the first vibration acceleration sensor 5 on the lower cover plate 2 of the controller and the position of the first excitation point 6 of the hammer, see the attached Figure 4 For the arrangement position of the first vibration acceleration sensor 5 on the rotary cover plate 3 and the position of the first excitation point 6 of the hammer, see the attached Figure 5 .

[0077] Step 1.2) Fourier calculation is performed on the vibration acceleration signal and force signal obtained in step 1.1) so that each signal is decomposed in the frequency domain.

[0078] Step 1.3) Divide the decomposed vibration acceleration signal and force signal point by point to obtain the frequency domain response function (frequency range: 0 to 3000 Hz).

[0079] Step 1.4) Calculate the average value of the four frequency domain response functions of the vibration acceleration signal and force signal in the frequency domain with a frequency interval of 1 Hz to obtain the final frequency domain response curve. The average value calculation formula is:

[0080]

[0081] Where: H i (ω) is the frequency response value of the ith subcomponent at frequency ω; a i (ω) is the vibration acceleration value of the ith subcomponent at frequency ω, F i (ω) is the excitation load value of the ith subcomponent at the frequency ω. The final frequency domain response curves of each subcomponent are shown in the attached figure. Figure 6 shown.

[0082] Step 2) Identify the modal frequencies of each subcomponent of the all-in-one motor assembly.

[0083] According to the frequency domain response curves of each subcomponent obtained in step 1), 50-order function, 100-order function and 150-order function are used for fitting respectively, and all roots on the denominators of 50-order function, 100-order function and 150-order function are calculated respectively, all roots are fitted with 50-order function, 100-order function and 150-order function respectively, and the minimum value among all roots is found, the minimum value among all roots of controller upper cover plate 1 is used as the first-order modal frequency of controller upper cover plate 1, the minimum value among all roots of controller lower cover plate 2 is used as the first-order modal frequency of controller lower cover plate 2, and the minimum value among all roots of resolver cover plate 3 is used as the first-order modal frequency of resolver cover plate 3.

[0084] Specifically, the formula for fitting with a 100-order function is:

[0085]

[0086] Where: ω1, ω2, …, ω 100 To solve all the roots, that is, the frequencies of the 100 fitted modes, b1, b2…, b 100 are the fitting coefficients for fitting the experimental data.

[0087] The formula for fitting with a 50-order function is:

[0088]

[0089] Where: ω1, ω2, …, ω 50 To solve all the roots, that is, the frequencies of the 50 modes fitted, b1, b2…, b 50 are the fitting coefficients for fitting the experimental data.

[0090] The formula for fitting with a 150-order function is:

[0091]

[0092] Where: ω1, ω2, …, ω 150 To solve all the roots, that is, the frequencies of the 150 modes fitted, b1, b2…, b 150 are the fitting coefficients for fitting the experimental data.

[0093] In this specific embodiment, the first-order modal frequencies of the controller upper cover 1, the controller lower cover 2, and the resolver cover 3 calculated are 347 Hz, 621 Hz, and 1247 Hz, respectively.

[0094] Step 3) Conduct a frequency domain response test of each suspension mounting point 4 of the all-in-one motor assembly.

[0095] Step 3.1) Install a screwdriver on each suspension mounting point 4 of the all-in-one motor assembly (the location of the suspension mounting point 4 is shown in the attached figure). Figure 1 and attached Figure 2 A second vibration acceleration sensor 7 is arranged at the middle diameter of the boss ring (as shown).

[0096] Step 3.2) The counterpoint position of each second vibration acceleration sensor 7 is used as the second excitation point 8, and a pulse normal excitation is applied at each second excitation point 8 using a force hammer, and each second excitation point 8 is excited in the three directions of X, Y, and Z, and the vibration acceleration signal of each second vibration acceleration sensor 7 position and the force signal at each second excitation point 8 are recorded; the positions of the second vibration acceleration sensor 7 and the second excitation point 8 are as shown in the attached figure. Figure 7 shown.

[0097] Step 3.3) Perform Fourier decomposition on the vibration acceleration signal and force signal obtained in step 3.2), divide the decomposed force signal point by point, and obtain the frequency domain response function (frequency range: 0 to 3000 Hz).

[0098] Step 3.4) Obtain the final frequency domain response curve according to the following formula;

[0099]

[0100] Where: H j (ω) is the frequency response value of the jth suspension installation point 4 at the frequency ω; a j (ω) is the vibration acceleration value of the jth suspension installation point 4 at the frequency ω, F j (ω) is the excitation load value of the jth suspension mounting point 4 at the frequency ω.

[0101] The final frequency domain response curve is shown in the attached figure. Figure 8shown.

[0102] Step 4) Calculate the dynamic stiffness of each suspension mounting point 4 of the all-in-one motor assembly.

[0103] The formula for calculating the dynamic stiffness curve (frequency range: 0-3000 Hz) based on the frequency domain response curve obtained in step 3) is:

[0104]

[0105] Where: K j (ω) is the dynamic stiffness value of the jth suspension installation point 4 at the frequency ω, H j (ω) is the frequency response value of the jth suspension installation point 4 when the frequency is ω.

[0106] The calculated dynamic stiffness results are shown in the attached Fig. 9 shown.

[0107] Step 5) performing a frequency domain response test of the all-in-one motor assembly;

[0108] Step 5.1) Arrange multiple third vibration acceleration sensors 9 on both side end faces and the middle interface of the all-in-one motor assembly. Specifically, arrange 4 third vibration acceleration sensors 9 on both side end faces of the all-in-one motor assembly, and arrange 5 third vibration acceleration sensors 9 on the middle interface. Use a hammer to hit the bottom center point of the middle interface of the all-in-one motor assembly (the third excitation point 10), and record the vibration acceleration signals of each third vibration acceleration sensor 9 and the force signal of the bottom center point of the middle interface of the all-in-one motor assembly. The position arrangement of the third vibration acceleration sensors 9 and the position arrangement of the third excitation point 10 on the all-in-one motor assembly is as shown in the attached figure. Fig.10 shown.

[0109] Step 5.2) Perform Fourier calculation on the vibration acceleration signal and force signal obtained in step 5.1) so that each signal is decomposed in the frequency domain.

[0110] Step 5.3) Divide the decomposed vibration acceleration signal and force signal point by point to obtain the frequency domain response function.

[0111] Step 5.4) Calculate the average value of multiple frequency domain response functions of the vibration acceleration signal and force signal in the frequency domain with a frequency interval of 1 Hz to obtain the final frequency domain response curve. The average value calculation formula is:

[0112]

[0113] Where: H r (ω) is the frequency response value of the installation point of the rth third vibration acceleration sensor 9 when the frequency is ω; a r(ω) is the vibration acceleration value of the installation point of the rth third vibration acceleration sensor 9 at the frequency ω, F r (ω) is the excitation load value of the installation point of the rth third vibration acceleration sensor 9 when the frequency is ω.

[0114] Step 5.5) uses the following formula to synthesize all the frequency domain response curves in step 5.4):

[0115]

[0116] Wherein: Hr(ω) is the frequency response value of the rth third vibration acceleration sensor 9 installation point when the frequency is ω, and Hsum(ω) is the composite value of the frequency response of all the third acceleration sensor installation points when the frequency is ω.

[0117] The synthesis result of frequency domain response curve is shown in the attached figure. Fig.11 shown.

[0118] Step 6) Modal frequency identification of the all-in-one motor assembly.

[0119] According to the frequency domain response curves of the installation points of the third vibration acceleration sensor 9 obtained in step 5), 50-order functions, 100-order functions and 150-order functions are used for fitting, and all roots on the denominators of the 50-order functions, 100-order functions and 150-order functions are calculated respectively. The fitting calculation formulas of the 50-order functions, 100-order functions and 150-order functions are the same as those in step 2). The roots obtained by the three fittings have the same value and are summarized (the same judgment basis: the roots of different fitting results have a frequency difference of <0.5 Hz). The values ​​of the first 4 smallest roots are recorded and recorded as the first, second, third and fourth modal frequencies of the all-in-one motor assembly. The first 4 modal frequencies calculated in this case are: 705 Hz, 824 Hz, 1247 Hz, 1308 Hz.

[0120] Step 7) Calculation and analysis of the dynamic stiffness performance of the all-in-one motor assembly.

[0121] Step 7.1) Calculate the total modal value of the all-in-one motor assembly according to the following formula;

[0122]

[0123] Wherein: U1 is the first-order modal frequency of the controller upper cover 1, L1 is the first-order modal frequency of the controller lower cover 2, T1 is the first-order modal frequency of the resolver cover 3, E1 is the first-order modal frequency of the all-in-one motor assembly, E2 is the second-order modal frequency of the all-in-one motor assembly, E3 is the third-order modal frequency of the all-in-one motor assembly, and E4 is the fourth-order modal frequency of the all-in-one motor assembly; the total modal value calculated in this case is: Fre=6.73.

[0124] Step 7.2) Calculate the total dynamic stiffness of each suspension mounting point 4 according to the following formula;

[0125]

[0126] Where: KK is the total dynamic stiffness of each mounting point 4; the total dynamic stiffness calculated in this case is: KK = 4.23. Step 7.3) Calculate the stiffness performance coefficient of the all-in-one motor assembly according to the following formula:

[0127] PerFFre+KK

[0128] Where: Per is the stiffness performance coefficient of the all-in-one motor assembly;

[0129] Step 7.4) Evaluate the stiffness performance of the all-in-one motor assembly based on the stiffness performance coefficient of the all-in-one motor assembly.

[0130] The stiffness performance coefficient of the all-in-one motor assembly calculated in this case is: Per = 10.96. The calculated coefficient is put into the scoring table to score the stiffness performance of the all-in-one motor assembly. The specific scoring table is shown in Table 1. The evaluation of the stiffness performance of the all-in-one motor assembly in this case is: good.

[0131] Table 1: Stiffness performance rating table of all-in-one motor assembly

[0132] score 1 point 2 points 3 points 4 points 5 points scope <5 5～7 7～9 9～11 >11 evaluate Very bad High risk qualified good excellent

[0133] Compared with the prior art, the present invention provides a method for quantifying the stiffness characteristics of an all-in-one motor assembly, which can quickly and effectively evaluate the product performance of the all-in-one motor assembly. The present invention achieves target positioning in the early stage of all-in-one motor assembly product development, providing an important basis for product optimization. The present invention can achieve rapid iteration of the all-in-one motor assembly without the support of test bench and vehicle resources, thereby shortening the development cycle, identifying risk issues in advance, and saving vehicle testing costs.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for analyzing the dynamic stiffness performance of an all-in-one motor assembly for a vehicle, characterized in that: The sub-components of the all-in-one motor assembly include a controller upper cover, a controller lower cover, and a resolver cover. The method includes the following steps: Step 1) performing a frequency domain response test of each subcomponent of the all-in-one motor assembly; Step 2) identifying the modal frequencies of each subcomponent of the all-in-one motor assembly; Step 3) performing a frequency domain response test of each mounting point of the all-in-one motor assembly; Step 4) Calculate the dynamic stiffness of each mounting point of the all-in-one motor assembly; Step 5) performing a frequency domain response test of the all-in-one motor assembly; Step 6) Modal frequency identification of the all-in-one motor assembly; Step 7) Calculation and analysis of the dynamic stiffness performance of the all-in-one motor assembly.

2. The dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle according to claim 1, characterized in that: Step 1) includes the following steps: Step 1.1) a first vibration acceleration sensor is arranged at the geometric center point of each subcomponent of the all-in-one motor assembly, and then a plurality of first excitation points are evenly arranged on a circle with the first vibration acceleration sensor as the center and the first set value as the radius, and a pulse normal excitation is applied at each first excitation point using a force hammer, and the vibration acceleration signal of the first acceleration sensor position of each subcomponent and the force signal at the first excitation point are recorded; Step 1.2) Perform Fourier calculation on the vibration acceleration signal and force signal obtained in step 1.1) so that each signal is decomposed in the frequency domain; Step 1.3) Divide the decomposed vibration acceleration signal and the force signal point by point to obtain a frequency domain response function; Step 1.4) Calculate the average value of multiple frequency domain response functions of the vibration acceleration signal and force signal in the frequency domain with a frequency interval of 1 Hz to obtain the final frequency domain response curve. The average value calculation formula is: Where: H i (ω) is the frequency response value of the ith subcomponent at frequency ω; a i (ω) is the vibration acceleration value of the ith subcomponent at frequency ω, F i (ω) is the excitation load value of the i-th subcomponent at frequency ω.

3. The dynamic stiffness performance analysis method of the all-in-one motor assembly for a vehicle according to claim 2, characterized in that: In step 2), according to the frequency domain response curve of each subcomponent obtained in step 1), 50-order function, 100-order function and 150-order function are respectively used for fitting, and all roots on the denominator of 50-order function, 100-order function and 150-order function are respectively calculated, all roots are respectively fitted with 50-order function, 100-order function and 150-order function, and the minimum value of all roots is found, the minimum value of all roots of the controller upper cover plate is used as the first-order modal frequency of the controller upper cover plate, the minimum value of all roots of the controller lower cover plate is used as the first-order modal frequency of the controller lower cover plate, and the minimum value of all roots of the resolver cover plate is used as the first-order modal frequency of the resolver cover plate.

4. The method for analyzing dynamic stiffness performance of an all-in-one motor assembly for a vehicle according to claim 1, characterized in that: Step 3) includes the following steps: Step 3.1) Arrange a second vibration acceleration sensor at the middle diameter of the boss ring of each suspension mounting point of the all-in-one motor assembly; Step 3.2) The counterpoint position of each second vibration acceleration sensor is used as the second excitation point, and a pulse normal excitation is applied at each second excitation point using a force hammer, and each second excitation point is excited in three directions of X, Y, and Z, and the vibration acceleration signal of each second vibration acceleration sensor position and the force signal at each second excitation point are recorded; Step 3.3) performing Fourier decomposition on the vibration acceleration signal and force signal obtained in step 3.2), dividing the decomposed force signal point by point to obtain a frequency domain response function; Step 3.4) Obtain the final frequency domain response curve according to the following formula; Where: H j (ω) is the frequency response value of the jth suspension installation point at the frequency ω; a j (ω) is the vibration acceleration value of the jth suspension installation point at the frequency ω, F j (ω) is the excitation load value of the jth suspension installation point at the frequency ω.

5. The method for analyzing dynamic stiffness performance of an all-in-one motor assembly for a vehicle according to claim 4, characterized in that: In step 4), the formula for calculating the dynamic stiffness curve based on the frequency domain response curve obtained in step 3) is: Where: K j (ω) is the dynamic stiffness value of the jth suspension installation point at the frequency ω, H j (ω) is the frequency response value of the jth suspension installation point at the frequency ω.

6. The method for analyzing dynamic stiffness performance of an all-in-one motor assembly for a vehicle according to claim 1, characterized in that: Step 5) includes the following steps: Step 5.1) Arrange multiple third vibration acceleration sensors on both side end surfaces and the middle interface of the all-in-one motor assembly, hit the bottom center point of the middle interface of the all-in-one motor assembly with a hammer, and record the vibration acceleration signals of each third vibration acceleration sensor and the force signal of the bottom center point of the middle interface of the all-in-one motor assembly; Step 5.2) Perform Fourier calculation on the vibration acceleration signal and force signal obtained in step 5.1) so that each signal is decomposed in the frequency domain; Step 5.3) Divide the decomposed vibration acceleration signal and the force signal point by point to obtain a frequency domain response function; Step 5.4) Calculate the average value of multiple frequency domain response functions of the vibration acceleration signal and force signal in the frequency domain with a frequency interval of 1 Hz to obtain the final frequency domain response curve. The average value calculation formula is: Where: H r (ω) is the frequency response value of the installation point of the rth third vibration acceleration sensor when the frequency is ω; a r (ω) is the vibration acceleration value of the installation point of the rth third vibration acceleration sensor at the frequency ω, F r (ω) is the excitation load value of the installation point of the rth third vibration acceleration sensor at the frequency of ω; Step 5.5) uses the following formula to synthesize all the frequency domain response curves in step 5.4): Where: H r (ω) is the frequency response value of the installation point of the rth third vibration acceleration sensor at the frequency ω, H sum (ω) is the composite value of the frequency response of all the third acceleration sensor installation points at the frequency ω.

7. The method for analyzing dynamic stiffness performance of an all-in-one motor assembly for a vehicle according to claim 6, characterized in that: In step 6), according to the frequency domain response curves of each third vibration acceleration sensor installation point obtained in step 5), 50-order function, 100-order function and 150-order function are used for fitting, and all roots on the denominator of the 50-order function, 100-order function and 150-order function are calculated respectively. The roots obtained by three fittings have the same value and are summarized. The values ​​of the first 4 smallest roots are recorded and recorded as the first, second, third and fourth modal frequencies of the all-in-one motor assembly.

8. The method for analyzing dynamic stiffness performance of an all-in-one motor assembly for a vehicle according to claim 7, characterized in that: Step 7) includes the following steps: Step 7.1) Calculate the total modal value of the all-in-one motor assembly according to the following formula; Wherein: U1 is the first-order modal frequency of the upper cover of the controller, L1 is the first-order modal frequency of the lower cover of the controller, T1 is the first-order modal frequency of the resolver cover, E1 is the first-order modal frequency of the all-in-one motor assembly, E2 is the second-order modal frequency of the all-in-one motor assembly, E3 is the third-order modal frequency of the all-in-one motor assembly, and E4 is the fourth-order modal frequency of the all-in-one motor assembly; Step 7.2) Calculate the total value of the dynamic stiffness of each suspension installation point according to the following formula; Where: KK is the total value of the dynamic stiffness of each suspension installation point; Step 7.3) Calculate the stiffness performance coefficient of the all-in-one motor assembly according to the following formula: Per=FFre+KK Where: Per is the stiffness performance coefficient of the all-in-one motor assembly; Step 7.4) Evaluate the stiffness performance of the all-in-one motor assembly based on the stiffness performance coefficient of the all-in-one motor assembly.

Images