A simulation and prediction method for eccentric noise of traction motor rotor

Abstract

The application discloses a simulation and prediction method for eccentric noise of a traction motor rotor, and relates to the field of motor noise simulation and prediction. Specifically, the size of the dynamic clearance of the bearing at the transmission end and the non-transmission end of the rotating shaft of the traction motor under the uniform speed working condition is calculated; the eccentric force borne by the rotor is calculated and generated according to the calculation result; a transient dynamics model of the excitation force of the traction motor rotor is established and calculated, and the physical quantity related to the vibration excitation is obtained after the transient dynamics calculation converges; the time-domain physical quantity related to the vibration excitation is converted into the frequency-domain physical quantity; a vibration response analysis model of the stator shell of the traction motor is established, the frequency-domain physical quantity related to the vibration excitation is loaded onto the vibration response analysis model, and the vibration response result is calculated; a radiation noise model of the outer surface of the traction motor is established, and the vibration response result is used to calculate the radiation noise, i.e. the rotor eccentric noise. The application reduces the calculation time of the noise excitation physical quantity, and realizes the accurate prediction of the rotor eccentric noise.

Description

Technical Field

[0001] This invention relates to the field of motor noise simulation and prediction, specifically to a method for simulating and predicting rotor eccentricity noise in a traction motor. Background Technology

[0002] Rotor eccentricity noise is a significant component of the mechanical noise of a motor. Currently, the performance evaluation of traction motor rotor eccentricity noise is mainly completed through field test data combined with the experience of technicians, and corresponding improvement measures are proposed to achieve noise reduction. However, this method lacks specific research and analysis of the rotor eccentricity noise sound field distribution and noise source characteristics, making it impossible to propose noise reduction solutions during the traction motor design phase. It still requires lengthy testing and improvement processes to achieve the goal of traction motor noise reduction. Therefore, a method for predicting the performance of motor rotor eccentricity noise is needed to better address the problem of traction motor noise reduction optimization.

[0003] The rotor eccentricity noise of a traction motor is mainly caused by the unbalanced forces acting on the rotor during rotation, which are transmitted to the stator housing through the bearings, thus causing housing vibration and generating radiated noise. Currently, there is no perfect simulation calculation method for traction motor rotor eccentricity noise; at the same time, for complex engineering models such as traction motors, there are often difficulties such as long calculation time and complex model processing. Summary of the Invention

[0004] To address the issues of long calculation times and complex model processing in traction motor rotor eccentricity noise calculation, this invention provides a simulation prediction method for traction motor rotor eccentricity noise.

[0005] This invention is achieved through the following technical solution: a simulation prediction method for rotor eccentricity noise of a traction motor, comprising the following steps: 1) Calculate the dynamic clearance of the bearings at the transmission end and the non-transmission end of the traction motor under constant speed operating conditions; 2) Based on the calculation results of step 1), calculate the eccentric force acting on the rotor; 3) Establishment of the transient dynamic model of the traction motor rotor excitation force; 4) Calculation of transient dynamic model of traction motor rotor excitation force. After the transient dynamic calculation converges, the physical quantities related to vibration excitation are obtained. 5) Convert the time-domain physical quantities related to vibration excitation obtained in step 4) into frequency-domain physical quantities; 6) Establish a vibration response analysis model for the stator housing of the traction motor, load the frequency domain physical quantities related to vibration excitation in step 5) onto the vibration response analysis model, and calculate the vibration response results; 7) Establish a radiated noise model of the outer surface of the traction motor, and calculate the radiated noise, i.e., rotor eccentric noise, using the vibration response results obtained in step 6).

[0006] Compared with the prior art, the present invention has the following beneficial effects: The simulation prediction method for traction motor rotor eccentricity noise provided by the present invention considers the influence of dynamic clearance of traction motor bearing on the magnitude of rotor eccentricity force, separates the rotor model from the stator shell model, and transforms the time-domain physical quantities output in the transient model into frequency-domain excitations in the vibration response model, thereby reducing the calculation time of noise excitation physical quantities and realizing accurate prediction of rotor eccentricity noise. Attached Figure Description

[0007] Figure 1 This is a flowchart illustrating the principle of the prediction method described in this invention. Detailed Implementation

[0008] The present invention will be further described below with reference to specific embodiments.

[0009] A simulation prediction method for rotor eccentricity noise of a traction motor, the process is as follows: Figure 1 As shown: It includes the following steps: 1) Calculate the dynamic clearance of the bearings at the transmission end and the non-transmission end of the traction motor under constant speed operating conditions; The theoretical value of bearing dynamic clearance is calculated based on the bearing dynamic clearance calculation formula in the instruction manual corresponding to the specific bearing model. If the parameters related to the bearing dynamic clearance calculation cannot be determined by calculation or experiment, then the empirical value is taken and a floating range is given before it is used in the calculation. In this embodiment, the empirical value is taken and a floating range of ±20% is given before it is used in the calculation.

[0010] 2) Based on the calculation results of step 1), calculate the eccentric force acting on the rotor; specifically: The rotor geometric model was imported into the ANSYS finite element analysis software, and corresponding material properties were assigned to all components to obtain the rotor's mass parameters. m The unit is kg; the eccentric force load in the time domain is generated in MATLAB software according to equation (1). Fx , Fy The unit is N; the rotor geometry model includes all rotating components; (1) In equation (1), e This represents the rotor mass eccentricity, in meters; it is obtained from the bearing dynamic clearance calculation results in step 1). w This represents the angular frequency corresponding to the motor speed, in rad / s. t The time is expressed in seconds (s), and the duration is... tThe time domain eccentric force is calculated to consist of a set of harmonic loads with a phase difference of one-quarter of the cycle length, and the harmonic frequency is the angular frequency of the motor speed.

[0011] 3) Establishment of the transient dynamic model of the traction motor rotor excitation force; A transient dynamic model of the traction motor rotor is established based on its structural form. The rotor includes all rotating parts except the bearings. Except for the shaft connected to the bearing, which retains a solid structure mesh, the remaining parts and geometry are replaced by mass points. The radial mechanical behavior of the bearings is simulated using nonlinear spring elements. The rotor geometry model was imported into the Transient Structure module of ANSYS finite element software. The parts of the shaft that mate with the bearings at the drive end and non-drive end were retained and meshed using a structural mesh. All other components were replaced with mass points. Two sets of mutually perpendicular nonlinear springs were set in the radial plane at the shaft-bearing mating positions at the drive end and non-drive end to simulate the radial mechanical behavior of the bearings. The stiffness of the springs was the radial stiffness of the bearings, input in the form of displacement-force. The orientation of the bearing springs at the drive end was parallel to that at the non-drive end.

[0012] 4) Calculation of the transient dynamic model of the traction motor rotor excitation force. After the transient dynamic calculation converges, the physical quantities related to the vibration excitation are obtained; specifically: The time-domain eccentric force load calculated in step 2) is applied to the transient dynamic model of the traction motor rotor as a remote force. The loading position of the remote force should be the total centroid position of the rotor. The centroid position of the rotor is located on the geometric center line of the rotor shaft along the axial direction. Its specific position on the center line of the shaft is calculated by the centroid theorem. First, the centroid positions of the rotor rotating parts of different materials are calculated, and then the total centroid position of all rotating parts is calculated. After the calculation is completed, the physical quantity related to vibration excitation output is the time-domain response force of the nonlinear springs at the drive end and non-drive end of the shaft.

[0013] 5) Convert the time-domain physical quantities related to vibration excitation obtained in step 4) into frequency-domain physical quantities. First, the time-domain spring response force output in step 4) needs to be interpolated to meet the requirements of the analysis frequency in the calculation results of the vibration response analysis model. Perform DFT transformation on the two sets of bearing spring response forces after interpolation to convert the time-domain physical quantities related to vibration excitation into frequency-domain physical quantities, including the transmission end and the non-transmission end, to obtain the real and imaginary amplitudes in the frequency domain and retain their phase information.

[0014] 6) Establish a vibration response analysis model for the stator housing of the traction motor. Load the frequency domain physical quantities related to vibration excitation in step 5) onto the vibration response analysis model and calculate the vibration response results. The vibration response model calculation method for the stator housing adopts harmonic response analysis based on the modal superposition method. The geometric model of the traction motor stator housing is imported into the ANSYS Modal module. The stator housing is a stationary part after removing rotating parts. A modal calculation model is established based on its structural form, and the mating parts are connected by linear contact. The modal solution order is set so that the highest natural frequency in the modal results is greater than 1.5 times the highest analysis frequency required in the vibration response results. The modal calculation results and finite element model are transferred to the harmonic response module in the ANSYS Harmonic Response module to obtain the harmonic response model of the traction motor stator housing. The real and imaginary amplitude loads of the spring response force obtained in step 5) in the frequency domain are applied to the bearing housing that mates with the bearing on the motor stator housing. The loading position and direction of the response force at the drive end and the non-drive end are consistent with the position and direction of the spring element in the transient dynamics of the traction motor rotor.

[0015] 7) Establish a radiated noise model of the outer surface of the traction motor, and calculate the radiated noise, i.e., rotor eccentricity noise, using the vibration response results obtained in step 6); The outer surface of the motor is meshed, and an air domain finite element model is established on its outer side. The motor vibration response obtained in step 6) is applied to the boundary element mesh on the motor surface through boundary conditions. The prediction results of the traction motor rotor eccentric vibration radiation noise in the frequency domain are calculated, and information such as noise spectrum and cloud map are output.

[0016] The scope of protection claimed by this invention is not limited to the specific embodiments described above. Moreover, for those skilled in the art, this invention can have various modifications and alterations. Any modifications, improvements, and equivalent substitutions made within the concept and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A simulation prediction method for rotor eccentricity noise of a traction motor, characterized in that: Includes the following steps: 1) Calculate the dynamic clearance of the bearings at the transmission end and the non-transmission end of the traction motor under constant speed operating conditions; 2) Based on the calculation results of step 1), calculate the eccentric force acting on the rotor; 3) Establishment of the transient dynamic model of the traction motor rotor excitation force; Specifically, a transient dynamic model of the traction motor rotor is established based on its structural form. The rotor includes all rotating parts except the bearings. Except for the shaft connected to the bearing, which retains a solid structure mesh, the remaining parts and geometry are replaced by mass points. The radial mechanical behavior of the bearings is simulated using nonlinear spring elements. The rotor geometry model was imported into the Transient Structure module of ANSYS finite element software. The parts of the shaft that mate with the bearings at the drive end and non-drive end were retained and meshed using a structural mesh. All other components were replaced with mass points. Two sets of mutually perpendicular nonlinear springs were set in the radial plane at the shaft-bearing mating positions at the drive end and non-drive end, respectively, to simulate the radial mechanical behavior of the bearings. The stiffness of the springs was the radial stiffness of the bearings, input in the form of displacement-force. The orientation of the bearing springs at the drive end was parallel to that at the non-drive end. 4) Calculation of transient dynamic model of traction motor rotor excitation force. After the transient dynamic calculation converges, the physical quantities related to vibration excitation are obtained. Specifically, the time-domain eccentric force load calculated in step 2) is applied to the transient dynamic model of the traction motor rotor as a remote force. The loading position of the remote force should be the total center of mass of the rotor. The center of mass of the rotor is located along the axial direction on the geometric center line of the rotor shaft. Its specific position on the center line of the shaft is calculated using the center of mass theorem. First, the center of mass positions of the rotor rotating parts made of different materials are calculated, and then the total center of mass position of all rotating parts is calculated. The physical quantities related to vibration excitation output after calculation are the nonlinear spring response forces in the time domain of the shaft drive end and non-drive end. 5) Convert the time-domain physical quantities related to vibration excitation obtained in step 4) into frequency-domain physical quantities; 6) Establish a vibration response analysis model for the stator housing of the traction motor, load the frequency domain physical quantities related to vibration excitation in step 5) onto the vibration response analysis model, and calculate the vibration response results; Specifically, the frequency domain physical quantities related to vibration excitation in step 5) are loaded onto the vibration response analysis model to obtain the vibration response results; the vibration response model calculation method for the stator shell adopts harmonic response analysis based on the modal superposition method. The geometric model of the traction motor stator housing is imported into the ANSYS Modal module. The stator housing is a stationary part after removing rotating parts. A modal calculation model is established based on its structural form, and the mating parts are connected by linear contact. The modal solution order is set so that the highest natural frequency in the modal results is greater than 1.5 times the highest analysis frequency required in the vibration response results. The modal calculation results and finite element model are transferred to the harmonic response module in the ANSYS Harmonic Response module to obtain the harmonic response model of the traction motor stator housing. The real and imaginary amplitude loads of the spring response force obtained in step 5) in the frequency domain are applied to the bearing housing that mates with the bearing on the motor stator housing. The loading position and direction of the response force at the drive end and the non-drive end are consistent with the position and direction of the spring element in the transient dynamics of the traction motor rotor. 7) Establish a radiated noise model of the outer surface of the traction motor, and calculate the radiated noise, i.e., rotor eccentric noise, using the vibration response results obtained in step 6).

2. The simulation prediction method for rotor eccentricity noise of a traction motor according to claim 1, characterized in that: In step 1), the theoretical value of the bearing dynamic clearance is calculated based on the bearing dynamic clearance calculation formula in the instruction manual corresponding to the specific bearing model; if the parameters related to the bearing dynamic clearance calculation cannot be determined by calculation or experiment, then the empirical value is taken and a floating range is given before participating in the calculation.

3. The simulation prediction method for rotor eccentricity noise of a traction motor according to claim 1, characterized in that: Step 2) specifically involves: importing the rotor geometric model into the ANSYS finite element analysis software, assigning corresponding material properties to all components, and obtaining the rotor's mass parameters. m The unit is kg; In MATLAB software, the eccentric force load in the time domain is generated according to equation (1). Fx , Fy The unit is N; the rotor geometry model includes all rotating components; （1） In equation (1), e This represents the rotor mass eccentricity, in meters; it is obtained from the bearing dynamic clearance calculation results in step 1). w This represents the angular frequency corresponding to the motor speed, in rad / s. t The time is expressed in seconds (s), and the duration is... t At least 1 second.

4. The simulation prediction method for rotor eccentricity noise of a traction motor according to claim 3, characterized in that: Step 5) Specifically, the time-domain spring response force output in step 4) needs to be interpolated to meet the frequency requirements of the vibration response analysis model calculation results. The two sets of interpolated bearing spring response forces are then subjected to DFT transformation to convert the time-domain physical quantities related to vibration excitation into frequency-domain physical quantities, including the transmission end and the non-transmission end, to obtain the real and imaginary amplitudes in the frequency domain and retain their phase information.

5. The simulation prediction method for rotor eccentricity noise of a traction motor according to claim 4, characterized in that: Step 7) specifically involves calculating the radiated noise, i.e., the rotor eccentricity noise, using the vibration response results obtained in step 6). The outer surface of the motor is divided into surface meshes, and an air domain finite element model is established on its outer side. The motor vibration response obtained in step 6) is applied to the boundary element mesh on the motor surface through boundary conditions. The prediction results of the traction motor rotor eccentric vibration radiation noise in the frequency domain are calculated, and the noise spectrum and cloud map are output.

6. The simulation prediction method for rotor eccentricity noise of a traction motor according to claim 2, characterized in that: In step 1), if the parameters related to the dynamic clearance of the bearing cannot be determined by calculation or experiment, empirical values ​​are taken and given a fluctuation range of ±20% before being included in the calculation.

7. The simulation prediction method for rotor eccentricity noise of a traction motor according to claim 3, characterized in that: In step 2), the calculated eccentric force in the time domain consists of a set of harmonic loads with a phase difference of one-quarter of the cycle length, and the harmonic frequency is the angular frequency of the motor speed.

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