Motor NVH test method and test device

Abstract

This invention discloses a method and apparatus for testing the NVH (Noise, Vibration, and Harshness) of a motor. The method includes the following steps: S1: acquiring the motor's rotational speed data and multi-degree-of-freedom vibration signals during operation; S2: obtaining a set of characteristic orders based on the number of stator slots and rotor pole pairs, and extracting key orders from the set using a VKF filter; S3: extracting the total multi-degree-of-freedom energy of the key orders; S4: comparing the total multi-degree-of-freedom energy of the key orders with a preset energy threshold to determine whether the motor's NVH is abnormal. This invention can improve the accuracy and efficiency of locating abnormal NVH points in a motor.

Description

Technical Field

[0001] This invention relates to the field of motor noise testing technology, and in particular to a method and apparatus for testing motor NVH (noise, vibration, and harshness). Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in new energy vehicles, industrial drives, and home appliances due to their high efficiency, high power density, and good control performance. However, the vibration, noise, and harshness (NVH) performance of PMSMs is one of the key indicators for evaluating their quality.

[0003] Currently, permanent magnet synchronous motor drive systems typically employ vector control or direct torque control strategies, which heavily rely on accurate rotor position feedback signals. To obtain this signal, position sensors such as resolvers and photoelectric encoders, along with corresponding signal processing circuits, must be installed in the system. This drive method complicates the motor drive system structure, increasing system cost and potential failure points. More importantly, the non-ideal characteristics of sensors and their interface circuits, signal sampling errors, and insufficient mechanical coupling stiffness between the sensors and the motor body all introduce additional electromagnetic interference and mechanical vibration, causing significant native interference to the NVH performance of the motor body, making it difficult to assess the NVH generated solely by the motor body.

[0004] In existing motor NVH testing methods, the motor under test is typically fixed to a fixed bench using rigid fixtures and connected to a dynamometer or load motor. In this setup, multiple degrees of freedom of the motor are constrained. These highly constrained boundary conditions differ significantly from the elastic mounting boundary conditions of the motor in actual operation. In practical applications, such as in electric vehicles, the motor is suspended on the vehicle frame, and its vibrations are transmitted to the vehicle body through the suspension system—a dynamic process involving multiple degrees of freedom coupling. Therefore, traditional fixed bench testing methods, due to the mismatch in boundary conditions, cannot accurately simulate and evaluate the vibration transmission characteristics and NVH performance of the motor under actual operating conditions, leading to a significant deviation between the test results and the actual performance of the end product—in other words, insufficient test accuracy. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method and system for testing the NVH (Noise, Vibration, and Harshness) of motors, thereby improving the testing accuracy.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for testing the NVH (noise, vibration, and harshness) of a motor includes the following steps: S1: Acquire the motor's rotational speed data and multi-degree-of-freedom vibration signals during operation; S2: Obtain a set of characteristic orders based on the number of stator slots and rotor pole pairs of the motor, and extract key orders from the set of characteristic orders using a VKF filter; S3: Extract the total energy of multiple degrees of freedom of key orders; S4: Compare the total energy of the key order of multiple degrees of freedom with the preset energy threshold to determine whether the motor's NVH is abnormal.

[0007] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is as follows: An NVH testing device for an electric motor includes a frame, elastic ropes, a support, a tensile testing assembly, an acceleration sensor, and at least two symmetrically arranged traction ropes. The elastic rope is suspended inside the top of the frame, and the bracket is connected to the elastic rope; the two sides of the motor under test are respectively connected to the frame by a traction rope. One end of the tensile testing assembly is connected to the frame, and the other end of the tensile testing assembly is connected to the motor under test; The beneficial effects of this invention are as follows: By suspending the motor under test, multi-degree-of-freedom vibration and speed signals are collected, placing the motor in an unconstrained state. This simulates the dynamic response characteristics of the motor under actual operating conditions. Dynamic testing covers the NVH performance across the entire speed range of the motor, eliminating external interference and improving data acquisition accuracy. A set of characteristic orders is obtained based on the number of stator slots and rotor pole pairs, and this set is used as the input parameters of a VKF filter. Using the real-time speed signal as a reference, key orders and their energy relevant to the motor under test are accurately extracted from the complex broadband vibration signal. Furthermore, by combining characteristic data such as the number of stator slots and rotor pole pairs, abnormal points in the motor can be quickly and accurately located, thus accurately determining the source of motor vibration. Compared to traditional motor NVH testing methods, this invention fully simulates the motor's state under actual use and obtains the complete operating speed of the motor through variable-speed dynamic testing, improving the reliability of test results. Moreover, this invention offers higher accuracy and faster location of vibration sources and achieves quantitative judgment of motor NVH anomalies. Attached Figure Description

[0008] Figure 1 This is a partial structural schematic diagram of the motor NVH testing device in this invention; Figure 2 This is a schematic diagram of the permanent magnet motor in this invention; Figure 3 This is a schematic diagram of the motor NVH testing device in this invention; Figure 4 This is a time-domain vibration curve from the motor test results in this invention; Figure 5 This is a speed-time curve from the motor test results in this invention; Figure 6 This is a graph showing the relationship between rotational speed and amplitude in the motor test results of this invention.

[0009] Label Explanation: 1. Frame; 2. Elastic rope; 3. Load connector; 4. Tensile test assembly; 41. Drive component; 42. Tensile gauge; 5. Traction rope; 6. Permanent magnet motor; 61. Drive motor; 62. Generator; 63. Tachometer; 7. Motor under test. Detailed Implementation

[0010] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0011] The overall inventive concept of this invention is as follows: By acquiring the motor's time-domain signal, namely vibration signal and speed data, and combining it with the number of stator slots and rotor pole pairs, the VKF filter uses these as input parameters. The VKF filter performs multi-order extraction based on the input parameters to obtain the key order, acquires the total energy of the key order's multiple degrees of freedom, and compares this total energy with a preset threshold to determine whether the motor's NVH is abnormal. Furthermore, by combining the order of the energy abnormality with the number of stator slots and rotor pole pairs, the abnormal points of the motor's NVH can be located.

[0012] Reference Figures 1-3 A motor NVH testing device includes a frame 1, elastic ropes 2, a support 3, a tension testing component 4, an accelerometer, and at least two symmetrically arranged traction ropes 5. The elastic ropes 2 are suspended inside the top of the frame 1, and the support 3 is connected to the elastic ropes 2. The two sides of the motor under test 7 are connected to the frame 1 via traction ropes 5 respectively. One end of the tension testing component 4 is connected to the frame 1, and the other end is connected to the motor under test 7. The accelerometer is disposed on the outer surface of the motor under test 7. Preferably, two elastic ropes 2 are provided, and the two elastic ropes 2 are symmetrically arranged. It is understood that by connecting the motor under test 7 to the frame 1 through the elastic ropes 2 and traction ropes 5, the motor under test 7 is in an unconstrained state. The accelerometer acquires the rotational speed data of the motor under test 7. The tension testing component 4 is used to apply an axial load to the motor under test 7 and facilitates adjustment of the magnitude of the axial load.

[0013] In some embodiments, the tensile testing assembly 4 includes a drive unit 41 and a force gauge 42. The drive unit 41 is connected to the bottom of the frame 1, and the drive unit 41 and the load connector 3 are connected via the force gauge 42. By setting the force gauge 42, the magnitude of the axial load can be quickly obtained. Preferably, the drive unit is an electric push rod or an electric pull rod.

[0014] In some embodiments, the accelerometer of the motor under test 7 is electrically connected to a data acquisition card to acquire vibration data of the motor under test 7. Preferably, the accelerometer is a triaxial accelerometer. The accelerometer converts the vibration energy of the motor under test 7 into a voltage signal and transmits it to the data acquisition card. Optionally, the data acquisition card can be an N1-4462 board with a built-in anti-aliasing filter. A motor NVH testing method includes the following steps: S1: Acquire the speed data and multi-degree-of-freedom vibration signal of the motor under operating conditions; S2: Obtain a set of characteristic orders based on the number of stator slots and rotor pole pairs of the motor, and extract key orders from the set of characteristic orders using a VKF filter; S3: Extract the total multi-degree-of-freedom energy of the key orders; S4: Compare the total multi-degree-of-freedom energy of the key orders with a preset energy threshold to determine whether the NVH of the motor is abnormal.

[0015] Understandably, a set of characteristic orders is obtained based on the number of stator slots and rotor pole pairs. This set of characteristic orders is then combined with multi-degree-of-freedom vibration signals and speed acquisition signals, and used as input parameters for a VKF filter. Using the real-time speed signal as a reference, key orders and their energy relevant to the tested motor 7 are accurately extracted from the complex broadband vibration signal. Furthermore, by combining characteristic data of the motor such as the number of stator slots and rotor pole pairs, abnormal points in the motor can be quickly and accurately located, thus accurately determining the source of motor vibration.

[0016] In some embodiments, the number of rotor pole pairs is P, 2P, 3P, and the number of stator slots is Z, 2Z, 3Z. Further, the sub-orders in both the order set of the rotor pole pairs and the order set of the stator slots are less than 30.

[0017] In some embodiments, the multi-degree-of-freedom vibration signal includes at least the vibration signals of the X-axis, Y-axis, and Z-axis, and the total multi-degree-of-freedom energy includes the energy of the X-axis, Y-axis, and Z-axis, to overcome the shortcomings of traditional single-axis motor NVH testing that is prone to missing detections. Since different faults may dominate vibrations in different directions during actual motor operation, selecting to acquire the energy of the X-axis, Y-axis, and Z-axis can comprehensively capture the vibration contribution in all directions, making the determination of vibration location more reliable.

[0018] In some embodiments, step S3 further includes S31: performing order analysis on key orders using short-time Fourier transform to obtain the vibration energy corresponding to each key order and obtaining a spectrum. The main purpose of order analysis using short-time Fourier transform is to convert the time-domain signal into a spectrum and obtain a spectrum. Specifically, the spectrum uses the order as the horizontal axis and the vibration energy of the corresponding order as the vertical axis. Obtaining the spectrum through short-time Fourier transform enables continuous tracking of NVH characteristics under variable speed conditions, accurately identifying the characteristic speed range where anomalies occur, and avoiding the limitations of single speed point testing. By observing the clarity of the target order spectral lines and the degree of background noise suppression in the spectrum, the extraction effect of the VKF filter can be intuitively verified. Furthermore, the variation law of energy of each characteristic order with speed / time can be observed. For example, the order with a sudden increase in energy at a specific speed can be identified, further accurately locating the operating point where anomalies occur. Specifically, the short-time Fourier transform is calculated using the following formula: Formula 1:

[0019] Where ω is the angular frequency and w(t) is the window function. For conjugate, τ is the width parameter, and t is the absolute time.

[0020] In some embodiments, step S3 further includes S32: extracting the corresponding order energy from the spectrum diagram to form an order tracking diagram and an energy diagram. The order tracking diagram clearly shows the energy change state of each order at different speeds, while the energy bar chart provides a clearer view of the energy value of each order. The formation of the order tracking diagram and energy diagram allows for a more intuitive presentation of NVH analysis results, enabling the analysis of NVH performance differences of the same motor under different conditions, and providing data support for motor condition adaptability assessment and design optimization.

[0021] In some embodiments, step S3 further includes S33: obtaining the total multi-degree-of-freedom energy of key orders based on the order tracking map and energy map, combined with the number of stator slots and rotor pole pairs of the motor. Specifically, the energy map is selected as an energy bar chart.

[0022] In some embodiments, step S33 includes extracting the order energy of the key order along the X, Y, and Z axes respectively, and summing the energy to obtain the total triaxial energy of the key order. Further, the total triaxial energy of the key order at different rotational speeds should be obtained. Specifically, taking a stator slot count of 12 and a rotor pole pair count of 8 as an example, the multiples or common multiples of the two are calculated to obtain the order with the larger energy as order 8. th 12 th 16 th and 24 thThis refers to the set of characteristic orders, which is used as input parameters into the VKF filter. The VKF filter then extracts the time-domain signals of the key orders based on the input parameters. Specifically, the total energy of the three axes is calculated using the following formula: Formula 2:

[0023] Where x, y, and z represent the vibration energy of the X-axis, Y-axis, and Z-axis, respectively.

[0024] In some embodiments, step S4 specifically involves comparing the total energy of the multiple degrees of freedom of the key order with a preset energy threshold; when the total energy of the multiple degrees of freedom is greater than the preset energy threshold, an NVH abnormality is determined, S1~S4 are repeated, and an alarm is issued; when the total energy of the multiple degrees of freedom is less than or equal to the preset energy threshold, an NVH normality is determined.

[0025] In some embodiments, step S1 involves suspending the motor 7 under test and acquiring its rotational speed data and multi-degree-of-freedom vibration signals during operation using an accelerometer and a data acquisition card. Specifically, the accelerometer and data acquisition card are attached to the surface of the motor 7 under test to accurately acquire its rotational speed and vibration data during operation.

[0026] Embodiment 1 of the present invention is as follows: Reference Figures 1-3 A motor NVH testing device includes a frame 1, elastic ropes 2, a bracket 3, a tensile testing component 4, an accelerometer sensor, and two symmetrically arranged traction ropes 5. The elastic ropes 2 are suspended inside the top of the frame 1, and the bracket 3 is connected to the elastic ropes 2. The two sides of the motor under test 7 are connected to the frame 1 via traction ropes 5 respectively. One end of the tensile testing component 4 is connected to the frame 1, and the other end is connected to the motor under test 7. The accelerometer sensor is disposed on the outer surface of the motor under test 7. Preferably, two elastic ropes 2 are provided, and the two elastic ropes 2 are symmetrically arranged. The accelerometer sensor is electrically connected to an external terminal data acquisition card to enable the data acquisition card to acquire data. Specifically, the bracket 3 is engaged with the output shaft of the motor under test 7, or the bracket 3 clamps the output shaft of the motor under test 7.

[0027] In some embodiments, the tensile testing assembly 4 includes a drive member 41 and a force gauge 42. The drive member 41 is connected to the bottom of the frame 1, and the drive member 41 and the motor 73 under test are connected via the force gauge 42. By setting the force gauge 42, the magnitude of the axial load can be quickly obtained. Preferably, the drive member 41 is an electric push rod, an electric pull rod, or other linear drive mechanism.

[0028] In some embodiments, the motor under test 7 is electrically connected to the permanent magnet motor 6, and the permanent magnet motor 6 supplies power to the motor under test 7. Specifically, the permanent magnet motor 6 includes a drive motor 61, a generator 62, and a tachometer 63. The output shaft of the drive motor 61 is drively connected to the input end of the generator 62. The detection end of the tachometer 63 is positioned opposite to the output shaft of the drive motor 61 to acquire the rotational speed data of the output shaft of the drive motor 61. The generator 62 is electrically connected to the motor under test 7.

[0029] The working principle of this embodiment is as follows: The motor under test 7 is connected to the elastic rope 2, and the output shaft of the motor under test 7 is connected to the bracket 3. An axial load is applied to the motor under test 7 through the drive component 41, and the tension gauge 42 measures the axial load. When the axial load reaches the preset value, the drive component 41 stops running. The vibration data and speed data of the motor are obtained by the acceleration sensor and data acquisition card on the surface of the motor under test 7.

[0030] Embodiment 2 of the present invention is as follows: A method for testing the NVH (noise, vibration, and harshness) of a motor includes the following steps: S1: Suspend the motor under test 7 and acquire the motor's rotational speed data and multi-degree-of-freedom vibration signals during operation through an accelerometer and a data acquisition card; the multi-degree-of-freedom vibration signals include vibration signals of the X-axis, Y-axis and Z-axis; S2: Obtain a set of characteristic orders based on the number of stator slots and rotor pole pairs of the motor. Extract key orders from the set of characteristic orders using a VKF filter. Specifically, the VKF filter extracts key orders from the set of characteristic orders based on the speed data and multi-degree-of-freedom vibration signals obtained in step S1. The rotor pole pairs are P, 2P, and 3P, and the stator slots are 1, 2Z, and 3Z, where P, 2P, and 3P are all less than 30, and 1, 2Z, and 3Z are all less than 30. S3: Extract the total energy of multiple degrees of freedom for key orders; the total energy of multiple degrees of freedom includes the energy of the X-axis, Y-axis and Z-axis. S31: Perform order analysis on key orders using short-time Fourier transform, and obtain the vibration energy corresponding to each key order on the X-axis, Y-axis and Z-axis respectively. Use the order as the horizontal axis and the corresponding vibration energy as the vertical axis to create a spectrum diagram. S32: Extract the order energies from orders 1 to 30 from the spectrum diagram to form order tracking diagrams and energy diagrams from orders 1 to 30; S33: Based on the order tracking diagram and energy diagram, combined with the number of stator slots and rotor pole pairs of the motor, the order energy of the key order in the X-axis, Y-axis and Z-axis is extracted respectively, and the energy is summarized to obtain the total multi-degree-of-freedom energy of the key order. S4: Compare the total energy of the multi-degree-of-freedom in the key order with the preset energy threshold to determine whether the NVH of the motor is abnormal; when the total energy of the multi-degree-of-freedom is greater than the preset energy threshold, the NVH is determined to be abnormal, S1~S4 are repeated and an alarm is issued; when the total energy of the multi-degree-of-freedom is less than or equal to the preset energy threshold, the NVH is determined to be normal; where, in this embodiment, the total energy of the multi-degree-of-freedom is the total energy of the three axes.

[0031] In summary, this invention discloses a method and apparatus for testing the NVH (Noise, Vibration, and Harshness) of a motor. The motor under test (7) is tested in a suspended manner to fully simulate the actual usage scenario of the motor. Dynamic testing is adopted, covering the NVH performance of the motor across its entire speed range, making the acquired vibration and speed data more accurate. The vibration data, speed data, and the number of stator slots and rotor pole pairs of the motor are used as input parameters for a VKF filter to extract key orders and their triaxial total energy, improving analysis efficiency. The pure orders after filtering by the VKF filter are analyzed by short-time Fourier transform, converting the time-domain signal into a spectrum, extracting the triaxial total energy of key orders, and combining preset thresholds to analyze whether there are anomalies in the key orders. If anomalies are found, the NVH anomaly points of the motor can be located through the orders with anomalies, making the analysis more accurate.

[0032] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for testing the NVH (Noise, Vibration, and Harshness) of a motor, characterized in that, Includes the following steps: S1: Acquire the motor's rotational speed data and multi-degree-of-freedom vibration signals during operation; S2: Obtain a set of characteristic orders based on the number of stator slots and rotor pole pairs of the motor, and extract key orders from the set of characteristic orders using a VKF filter; S3: Extract the total energy of the multi-degree-of-freedom of the key orders; S4: Compare the total energy of the multi-degree-of-freedom in the key order with a preset energy threshold to determine whether the NVH of the motor is abnormal.

2. The method for testing the NVH (Noise, Vibration, and Harshness) of a motor according to claim 1, characterized in that, The multi-degree-of-freedom vibration signal includes at least the vibration signals of the X-axis, Y-axis and Z-axis, and the total multi-degree-of-freedom energy includes the energy of the X-axis, Y-axis and Z-axis.

3. The method for testing the NVH (Noise, Vibration, and Harshness) of a motor according to claim 1, characterized in that, Step S3 further includes S31: performing order analysis on the key orders through short-time Fourier transform, obtaining the vibration energy corresponding to each key order, and obtaining a spectrum diagram.

4. The motor NVH testing method according to claim 3, characterized in that, Step S3 further includes S32: extracting the corresponding order energy from the spectrum diagram to form an order tracking diagram and an energy diagram.

5. The motor NVH testing method according to claim 4, characterized in that, Step S3 further includes S33: Based on the order tracking diagram and energy diagram, the total energy of multiple degrees of freedom of the key order is obtained by combining the number of stator slots and rotor pole pairs of the motor.

6. The method for testing the NVH (Noise, Vibration, and Harshness) of a motor according to claim 5, characterized in that, Step S33 includes extracting the order energy of the key order along the X-axis, Y-axis, and Z-axis respectively, and summing the energy to obtain the total energy of the key order across the three axes.

7. The method for testing the NVH (Noise, Vibration, and Harshness) of a motor according to claim 1, characterized in that, Specifically, step S4 involves comparing the total energy of the multiple degrees of freedom of the key order with a preset energy threshold. When the total energy of the multi-degree-of-freedom is greater than the preset energy threshold, NVH is determined to be abnormal.

8. The method for testing the NVH (Noise, Vibration, and Harshness) of a motor according to claim 1, characterized in that, The rotor has P, 2P, and 3P pole pairs, and the stator has Z, 2Z, and 3Z slots.

9. The method for testing the NVH (Noise, Vibration, and Harshness) of a motor according to claim 1, characterized in that, Step S1 involves suspending the motor under test and acquiring its rotational speed data and multi-degree-of-freedom vibration signals during operation using an accelerometer and a data acquisition card.

10. A testing apparatus applied in the motor NVH testing method according to any one of claims 1 to 9, characterized in that, It includes a frame, elastic ropes, support, tensile testing components, acceleration sensors, and at least two symmetrically arranged traction ropes; The elastic rope is suspended inside the top of the frame, and the bracket is connected to the elastic rope; the two sides of the motor under test are respectively connected to the frame through a traction rope. One end of the tensile testing assembly is connected to the frame, and the other end of the tensile testing assembly is connected to the motor under test; The acceleration sensor is mounted on the outer surface of the motor being tested.

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