Three-in-one electric drive assembly multi-physical coupling NVH analysis optimization method

Abstract

The invention relates to the field of NVH (Noise Vibration and Harshness) of electric vehicles, in particular to a three-in-one electric drive assembly multi-physical coupling NVH analysis and optimization method, which comprises the following steps: S1, optimizing a permanent magnet synchronous motor; and S2, analyzing and optimizing the rotary transformer cover plate and the upper cover plate. According to the method, the permanent magnet synchronous motor is optimized, an electromagnetic model is established for calculation, tooth cutting slotting is performed on the stator of the permanent magnet synchronous motor in different conditions, noise generated by the permanent magnet synchronous motor is reduced, and a rotary transformer cover plate and an upper cover plate of the target permanent magnet synchronous motor are further analyzed and optimized; the noise transmitted by the permanent magnet synchronous motor is reduced by changing the material property and the material structure and adding the damping plate.

Description

Technical Field

[0001] The present invention relates to the field of NVH of electric vehicles, and in particular to a multi-physics coupling NVH analysis and optimization method for a three-in-one electric drive assembly. Background Art

[0002] Pure electric vehicles all use electric drive as a new drive system assembly. The assembly is a structural coupling system consisting of a motor, a controller, and a reducer, collectively referred to as a "three-in-one" electric drive system assembly. The complex electromagnetic, mechanical, and multi-physical coupling of the powertrain system makes NVH research a difficult and important issue. As the main source of NVH problems in electric vehicles, accurate modeling and optimization analysis of the powertrain system is very important.

[0003] At present, the optimization of vibration and noise of electric drive assembly mainly focuses on motor electromagnetic force excitation, motor torque pulsation and housing flexibility. However, there are relatively few studies on the correlation between the vibration and noise of the upper cover plate and the rotary transformer cover plate of the electric drive assembly and the vibration and noise of the electric drive assembly, and how to improve the overall NVH characteristics of the electric drive assembly through optimization from multiple physical perspectives. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a three-in-one electric drive assembly multi-physics coupling NVH analysis and optimization method.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a three-in-one electric drive assembly multi-physics coupling NVH analysis and optimization method, and the specific steps are as follows:

[0007] S1. Optimize the permanent magnet synchronous motor by calculating the air gap flux density of the motor through the electromagnetic force waves of the stator and rotor, and perform tooth cutting and slotting on the stator of the permanent magnet synchronous motor to reduce the noise generated by the permanent magnet synchronous motor;

[0008] S2. Analyze and optimize the rotary transformer cover and upper cover, increase the stiffness of the original rotary transformer cover and upper cover, and improve them into a multi-layer structure to reduce the Hertz in the resonance area; set damping plates at the original rotary transformer cover and upper cover to reduce the noise generated.

[0009] As a preferred technical solution of the present invention, step S1 further includes:

[0010] S11. Data collection: collecting the internal structure data of the target permanent magnet synchronous motor, including the number of motor pole pairs, the number of stator slots, the air gap permeance and the permanent magnet data;

[0011] S12. Establish an electromagnetic model for calculation, calculate the armature magnetic potential and permanent magnet magnetic potential of the permanent magnet synchronous motor through the collected data to obtain the air gap magnetic potential, and finally obtain the air gap electromagnetic field density; establish a function model through the data collected in S11 to calculate and obtain a specific electromagnetic force comparison data diagram;

[0012] S13. Determine the slot size, and calculate the stators with different slot depths according to the function model established in S12 to determine the target permanent magnet synchronous motor stator with slots of appropriate depth.

[0013] As a preferred technical solution of the present invention, step S2 further includes:

[0014] S21. Data collection, collecting material properties of the target permanent magnet synchronous motor's resolver cover and upper cover;

[0015] S22. Establish a model calculation for static loads, construct a model related to static loads, including the static stiffness and dynamic loads of the system, set a degree of freedom elastic damping system under the dynamic load, and construct a value in which the dynamic stiffness is equal to the static stiffness according to the dynamic stiffness of the damping system;

[0016] S23. Determine the materials of the resolver cover and the upper cover. According to the model of S22, construct dynamic stiffness comparison of the resolver cover and the upper cover under different selected material stiffnesses, so as to further improve the material selection for the resolver cover and the upper cover based on S11-S13.

[0017] As a preferred technical solution of the present invention, in step S2, the multilayer structure is specifically a sandwich structure, the upper layer and the lower layer are both raw materials of the rotary transformer cover plate and the upper cover plate, and the middle layer is a vibration isolation and damping material.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1: The present invention optimizes the permanent magnet synchronous motor, establishes an electromagnetic model calculation, performs tooth cutting and slotting on the stator of the permanent magnet synchronous motor under different conditions, reduces the noise generated by the permanent magnet synchronous motor, and reduces the impact of noise from the noise source of the permanent magnet synchronous motor.

[0020] 2: The present invention further analyzes and optimizes the resolver cover plate and upper cover plate of the target permanent magnet synchronous motor, by changing their material properties and material structure and adding a damping plate, thereby reducing the noise transmitted by the permanent magnet synchronous motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 It is a "V+-" structure permanent magnet synchronous motor of the present invention;

[0023] Figure 2 It is a schematic diagram of the stator slotting structure of the present invention;

[0024] Figure 3 It is a schematic diagram of the comparison of 48-order electromagnetic forces of the present invention;

[0025] Figure 4 It is a schematic diagram of the reinforcement of the rotary transformer cover;

[0026] Figure 5 It is a schematic diagram of the upper cover reinforcement;

[0027] Figure 6 This is a schematic diagram of the comparison of dynamic stiffness of the rotary transformer cover;

[0028] Figure 7 It is a schematic diagram of the comparison of dynamic stiffness of the upper cover. DETAILED DESCRIPTION

[0029] Mechanical excitation and electromagnetic excitation are the main excitation sources that cause the vibration of the powertrain housing structure. In the powertrain system, electromagnetic excitation and mechanical excitation need to be considered comprehensively. The three-in-one electric drive system assembly of a certain electric vehicle was tested and analyzed to determine the main order of vibration noise caused by it. The main order noise is mainly generated in two aspects, one is the 8th order (mechanical noise caused by the excitation of the motor rotor unbalance), 24th order (0th order 24th frequency electromagnetic force generated by the interaction between the 5th and 7th order of the stator and the 5th and 7th order of the rotor) and 48th order (0th order 48th frequency electromagnetic force generated by the interaction between the 11th and 13th order of the stator and the 11th and 13th order of the rotor) electromagnetic vibration noise. One is from the reducer, which is a two-stage gear reducer. The first-stage gear ratio is 63 / 22 and the second-stage gear ratio is 69 / 17. Therefore, the orders of the gear howling noise are 22nd (reducer gear order), 5.94th (reducer main reduction order) and 11.88th.

[0030] Permanent magnet synchronous motors have been widely used in the fields of automobiles, household appliances, and ships due to their advantages such as high efficiency and high density. When designing the drive motors used in electric vehicles, high power density, lightweight and miniaturization, and wide range of speed regulation are pursued. Therefore, the motor structure is complex and the stiffness is low, which increases the difficulty of suppressing electromagnetic vibration noise. The main cause of motor vibration noise is the influence of the stator and rotor electromagnetic force waves, which are generated by the harmonic magnetic field of the stator and rotor air gap. Among them, the radial component is the main source of electromagnetic noise, and the tangential component is the secondary source of electromagnetic noise. The drive motor of this three-in-one electric drive system is an 8-level 48-slot permanent magnet synchronous motor, which adopts an electromagnetic scheme with a "V+1" permanent magnet structure, such as Figure 1 shown.

[0031] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0032] Example 1

[0033] The present invention provides a three-in-one electric drive assembly multi-physics coupling NVH analysis and optimization method, and the specific steps are as follows:

[0034] S1. Optimize the permanent magnet synchronous motor by calculating the air gap flux density of the motor through the electromagnetic force waves of the stator and rotor, and perform tooth cutting and slotting on the stator of the permanent magnet synchronous motor to reduce the noise generated by the permanent magnet synchronous motor;

[0035] S11. Data collection: collecting the internal structure data of the target permanent magnet synchronous motor, including the number of motor pole pairs, the number of stator slots, the air gap permeance and the permanent magnet data;

[0036] S12. Establish an electromagnetic model for calculation, calculate the armature magnetic potential and permanent magnet magnetic potential of the permanent magnet synchronous motor through the collected data to obtain the air gap magnetic potential, and finally obtain the air gap electromagnetic field density; establish a function model through the data collected in S11 to calculate and obtain a specific electromagnetic force comparison data diagram;

[0037] S13. Determine the slot size, and calculate the stators with different slot depths according to the function model established in S12 to determine the target permanent magnet synchronous motor stator with slots of appropriate depth.

[0038] Specifically, in step S1, the air gap magnetic field generated by the joint action of the rotor permanent magnet and the stator winding in the permanent magnet synchronous motor has the characteristics of changing continuously with time and space, and both are rotating magnetic fields. When the influence of the core magnetic resistance saturation is ignored, the product of the air gap magnetic potential and the air gap magnetic permeance is the air gap electromagnetic field density, which is:

[0039] B(θ,t)=f(θ,t)·Λ(θ,t) (1)

[0040] Where, B(θ, t): air gap electromagnetic field density; f(θ, t): air gap magnetic potential; Λ(θ, t): air gap magnetic permeability;

[0041] The expression of its air gap magnetic potential f(θ, t) is:

[0042] f(θ, t) = f v (θ,t)+f u (θ, t) (2)

[0043] In the formula, f v (θ, t): armature magnetic potential; f u (θ, t): magnetic potential of permanent magnet;

[0044] Its armature magnetomotive force f v (θ, t) is expressed as:

[0045]

[0046] In the formula, F v : Amplitude of the armature harmonic magnetomotive force; ω1 is the angular velocity of the current; The included angle between the stator winding magnetomotive force and the rotor permanent magnet magnetomotive force; v: Harmonic order of the armature magnetomotive force;

[0047] When the number of stator slots is an integer: v = (6k + 1)p, k = 0, ±1, ±2, ±3…, when the number of stator slots is a fraction: Where p: Pole pairs of the motor;

[0048] The permanent magnet magnetomotive force f μ (θ, t) is expressed as:

[0049]

[0050] In the formula, F μ : Amplitude of the permanent magnet harmonic magnetomotive force;

[0051] μ: Harmonic order of the permanent magnet magnetomotive force μ = (2k + 1)p, k = 1, 2, 3…

[0052] According to formulas (1 - 4), the air-gap magnetic density of the motor under sinusoidal excitation can be obtained as:

[0053] B(θ, t) = [f v (θ, t) + f u (θ, t)]·Λ(θ, t) (5)

[0054] The noise generated by the motor can be divided into electromagnetic noise, mechanical noise, and aerodynamic noise according to its main vibration sources. Electromagnetic noise comes from electromagnetic vibration, and electromagnetic vibration is excited by the exciting force wave generated by the action of the motor air-gap magnetic field on the motor iron core. And the main magnetic field in the air-gap of the permanent magnet synchronous motor is established by the magnetic flux density generated by the permanent magnet. Therefore, for the original "V + one" structure, the stator slotting "V + one (04)" scheme is carried out, as Figure 2 shown by the line coil. After the stator of the permanent magnet motor is slotted and cut, the air-gap of the slotted part is enlarged and is no longer a uniform air-gap. The electromagnetic force received is no longer perpendicular to the stator tooth surface, which reduces the transmission and radiation of the radial force wave to a certain extent; after building the modeling of steps S11 - S13 through the above process, after the stator is slotted and cut, the electromagnetic force of "V + one (04)" is simulated again through Maswell in Ansys. The results are as Figure 3As shown in the figure, it is obvious that the V+-(04) electromagnetic scheme has a significantly lower electromagnetic force in the entire speed range than the V+-48 order electromagnetic scheme.

[0055] Example 2

[0056] On the basis of Example 1, a step S2 is further designed, S2. The resolver cover plate and the upper cover plate are analyzed and optimized, the stiffness of the original resolver cover plate and the upper cover plate is increased, and the structure is improved into a multi-layer structure to reduce the Hertz in the resonance area; a damping plate is arranged at the original resolver cover plate and the upper cover plate to reduce the noise generated;

[0057] S21. Data collection, collecting material properties of the target permanent magnet synchronous motor's resolver cover and upper cover;

[0058] S22. Establish a model calculation for static loads, construct a model related to static loads, including the static stiffness and dynamic loads of the system, set a degree of freedom elastic damping system under the dynamic load, and construct a value in which the dynamic stiffness is equal to the static stiffness according to the dynamic stiffness of the damping system;

[0059] S23. Determine the materials of the resolver cover and the upper cover. According to the model of S22, construct dynamic stiffness comparison of the resolver cover and the upper cover under different selected material stiffnesses, so as to further improve the material selection for the resolver cover and the upper cover based on S11-S13.

[0060] In step S2, the multilayer structure is specifically a sandwich structure, the upper layer and the lower layer are both raw materials of the rotary transformer cover plate and the upper cover plate, and the middle layer is a vibration isolation and damping material.

[0061] For linear systems, stiffness is expressed as the ratio between the load force F acting on the system and its load deformation D. Just like the modal parameters of the system (vibration shape, frequency and damping), stiffness is also an inherent characteristic of the system and is not affected by external loads and responses.

[0062] Apply a static load to the system and measure the displacement response. The ratio of the two can be used to obtain the static stiffness of the system, which is expressed as follows:

[0063] K=F / D (6)

[0064] Where, K: static stiffness, unit N / mm; D: displacement response, unit mm; F: load, unit N.

[0065] When a dynamic load (load with frequency) is applied to the system

[0066] The dynamic stiffness of the system can be obtained by measuring the ratio of the two. The dynamic stiffness expression is derived as follows:

[0067] First, for a single-degree-of-freedom elastic damping system, its dynamic equation is:

[0068]

[0069] In order to solve equation (6), the displacement response x and the excitation force f are set as:

[0070]

[0071] Substituting the above formula (7) into formula (6), we can get the dynamic stiffness expression:

[0072]

[0073] In the formula, k d : is the dynamic stiffness, unit is N / mm;

[0074] From the dynamic stiffness expression, we can know that the dynamic stiffness is a function related to the excitation frequency. The stiffness value changes with the change of frequency ω and is no longer a fixed value. It contains real and imaginary parts, and its amplitude is:

[0075]

[0076] When the excitation frequency ω=0, equation (8) becomes:

[0077] k d =k

[0078] That is, at this time, the dynamic stiffness is equal to the static stiffness, so the static stiffness is a special case of dynamic stiffness. The dynamic stiffness is reflected in the change of stiffness with frequency, and the full frequency band is evaluated. The greater the dynamic stiffness, the smaller the vibration amplitude. Dynamic stiffness comprehensively considers the influence of mass, material elasticity, and damping. Its vibration displacement and vibration velocity are similar to the dynamic stiffness evaluation.

[0079] The dynamic stiffness in the automotive industry is widely used to evaluate the structural stiffness and suspension stiffness of the powertrain. The suspension points, motor reducer bearing chambers, stator assemblies, cover plates and other components in the electric drive system should not only be evaluated by modal frequency, but also by dynamic stiffness. That is, dynamic stiffness is an important physical quantity that describes the degree of response of an object to external forces.

[0080] Since the resolver cover and upper cover in the electric drive assembly are thin plate structures, the axial bending stiffness is weak and it is easy to generate axial bending mode vibration under the action of the exciting force. In order to suppress the vibration of the housing end cover, it is necessary to enhance the stiffness of the resolver cover structure. And based on the Optistiuct card in Hypermesh, the resolver cover structure is optimized and enhanced, such as Figure 4 , 5As shown. It can be clearly seen from the simulation results that after the resolver cover plate is strengthened, the vibration amplitude point at 2000 Hz is significantly reduced, and the peak values of the vibration amplitudes at 5200 Hz and 8000 Hz disappear, indicating that the dynamic stiffness of the resolver cover plate is significantly enhanced. After the upper cover plate is strengthened, its dynamic stiffness is slightly enhanced, the peak point of the vibration amplitude at 900 Hz is reduced, and the peak point of the vibration amplitude at about 1700 Hz is reduced, as Figure 6 、 Figure 7 shown.

[0081] At the same time, regarding the influence of different materials on the resolver cover plate, the vibration and noise optimization performance will be compared by changing the materials. The original resolver cover plate material is ordinary aluminum alloy, and the raw material will be changed to a composite solution of a "sandwich" material with a spacer material.

[0082] The composite solution will be tested on a test bench and compared with the original solution. Under the WOT condition, the results show that compared with the original solution for the resolver cover plate "sandwich" composite solution Y vibration, the original resonance bands at 2500 - 3000 Hz and 4000 - 4500 Hz disappear; the resonance band at about 1600 Hz is significantly weakened, and the resonance region at 8500 - 9000 Hz under 2000 - 8000 rpm is significantly weakened, which significantly improves the NVH performance of the electric drive assembly.

[0083] Damping helps to reduce the ability of the structure to transmit vibration. Regarding the vibration and noise of its upper cover plate, a damping plate can be added to reduce its vibration and noise, and at the same time, a feasibility test is carried out for verification. Comparing the upper cover plate with damping solution and the original cover plate through a test bench test, under the WOT condition, the resonance bands at 816 Hz and 2057 Hz disappear, the 24th order and 48th order are significantly weakened, and the resonance region at 7500 Hz - 9000 Hz is significantly weakened, which significantly improves the NVH performance of the electric drive assembly.

[0084] To sum up, integrating the "V + one (04)" stator slotting, the resolver cover plate composite material, and the upper cover plate with damping into the same electric drive assembly, and conducting a multi - physical - field coupled vibration and noise vehicle test. Through the analysis of the vehicle test results, it can be obtained that under the WOT condition, from the near - field of the motor and the waterfall plot in the vehicle, it can be clearly seen that the 5.94th order, 11.88th order, 22nd order, 48th order of the reducer and the 8th order, 24th order, 48th order of the motor are significantly weakened first. And the resonance bands at 1000 Hz and 1800 Hz in the near - field and the resonance band at 1000 Hz in the vehicle are significantly weakened.

[0085] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A three-in-one electric drive assembly multi-physics coupling NVH analysis and optimization method, characterized in that: The specific steps are as follows: S1. Optimize the permanent magnet synchronous motor by calculating the air gap flux density of the motor through the electromagnetic force waves of the stator and rotor, and perform tooth cutting and slotting on the stator of the permanent magnet synchronous motor to reduce the noise generated by the permanent magnet synchronous motor; S2. Analyze and optimize the rotary transformer cover and upper cover, increase the stiffness of the original rotary transformer cover and upper cover, and improve them into a multi-layer structure to reduce the Hertz in the resonance area; set damping plates at the original rotary transformer cover and upper cover to reduce the noise generated.

2. The three-in-one electric drive assembly multi-physics coupling NVH analysis and optimization method according to claim 1 is characterized in that: Step S1 also includes: S11. Data collection: collecting the internal structure data of the target permanent magnet synchronous motor, including the number of motor pole pairs, the number of stator slots, the air gap permeance and the permanent magnet data; S12. Establish an electromagnetic model for calculation, calculate the armature magnetic potential and permanent magnet magnetic potential of the permanent magnet synchronous motor through the collected data to obtain the air gap magnetic potential, and finally obtain the air gap electromagnetic field density; establish a function model through the data collected in S11 to calculate and obtain a specific electromagnetic force comparison data diagram; S13. Determine the slot size, and calculate the stators with different slot depths according to the function model established in S12 to determine the target permanent magnet synchronous motor stator with slots of appropriate depth.

3. The three-in-one electric drive assembly multi-physics coupling NVH analysis and optimization method according to claim 2 is characterized in that: Step S2 also includes: S21. Data collection, collecting material properties of the target permanent magnet synchronous motor's resolver cover and upper cover; S22. Establish a model calculation for static loads, construct a model related to static loads, including the static stiffness and dynamic loads of the system, set a degree of freedom elastic damping system under the dynamic load, and construct a value in which the dynamic stiffness is equal to the static stiffness according to the dynamic stiffness of the damping system; S23. Determine the materials of the resolver cover and the upper cover. According to the model of S22, construct dynamic stiffness comparison of the resolver cover and the upper cover under different selected material stiffnesses, so as to further improve the material selection for the resolver cover and the upper cover based on S11-S13.

4. The three-in-one electric drive assembly multi-physics coupling NVH analysis and optimization method according to claim 1 is characterized in that: In step S2, the multilayer structure is specifically a sandwich structure, the upper layer and the lower layer are both raw materials of the rotary transformer cover plate and the upper cover plate, and the middle layer is a vibration isolation and damping material.

Images