Gear transmission system electromechanical coupling modeling method and application

Abstract

This invention discloses a method and application for electromechanical coupling modeling of gear transmission systems. The steps are as follows: First, a 3D model is completed based on the 3D parameters of key components of the actual gearbox, and imported into Ansys Motion to establish a rigid-flexible coupling model of a single-stage fixed-axis gear transmission. Then, a three-phase asynchronous motor model is constructed based on Simulink, and dynamic coupling with the rigid-flexible coupling model is achieved through a speed-torque closed-loop interface to form an electromechanical coupling model. Subsequently, the frequency domain vibration response signals of the output gears under the two models are calculated respectively. Finally, the signals under normal and broken tooth fault states are compared and analyzed to obtain the influence law of the motor drive end and incorporate it into the diagnostic feature library. This method uses the finite element method to improve the realism of the model, clarifies the additional modulation sideband influence brought about by electromechanical coupling, improves the accuracy of fault diagnosis, provides a reliable reference for the safe maintenance of industrial equipment, and is both practical and economical.

Description

Technical Field

[0001] This invention belongs to the field of mechanical engineering technology, specifically relating to a method for electromechanical coupling modeling of gear transmission systems and its application. Background Technology

[0002] Gear drives are widely used in the transmission systems of equipment such as automobiles, wind turbines, and helicopters. They are an indispensable part of the power transmission process in the operation of equipment. However, gears generally work in harsh environments and for long periods of time, which can easily lead to gear failures, thereby reducing their working efficiency and even causing incalculable economic losses and serious consequences such as personal injury.

[0003] In the last century, equipment inspection and maintenance technologies were relatively backward, significantly hindering industrial production efficiency. Equipment monitoring methods were rudimentary, relying primarily on manual inspections and simple instrument testing. Many production lines lacked automatic monitoring systems. Operators relied on their experience to determine equipment malfunctions, and basic measuring instruments were essential. However, these instruments often provided only single numerical values, lacking systematic data analysis and comprehensive fault diagnosis capabilities. This information lag made timely and scientific maintenance planning difficult, resulting in prolonged equipment downtime and directly impacting production efficiency. Therefore, there is increasing focus on monitoring equipment operating status to ensure safe and stable operation. Accurate modeling of gear systems is a necessary prerequisite for studying gear frequency domain vibration response. To this end, many researchers employ various methods such as lumped parameter methods, phenomenological models, and finite element methods to model gear transmissions. Lumped parameter method and finite element method are currently the mainstream methods for dynamic modeling of gear transmission systems. Although the lumped parameter method is easier to model, its computational accuracy lags behind that of the finite element method. Furthermore, the lumped parameter method can only construct gear faults by modifying parameter values, while the finite element method can replicate actual fault characteristics during geometric modeling by observing actual gear fault conditions. Therefore, compared to the finite element method, using it to model gears can better reproduce the gear transmission situation.

[0004] However, most studies analyze the frequency domain vibration response obtained from their own established models. But these artificially assumed gear health conditions inevitably deviate from reality, especially models built using numerical methods such as lumped parameter methods, which often exhibit even greater deviations, ultimately affecting the accuracy of the diagnosis. Furthermore, most studies only model the gear transmission component and only set up the gear drive by providing numerical values, without considering the impact of the motor as the drive unit on the gear transmission component. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and application for electromechanical coupling modeling of gear transmission systems. The electromechanical coupling model constructed by this invention can effectively explore the impact of the motor as the driving end on the gear transmission part, improve the accuracy of fault diagnosis of gear transmission systems, protect the safe operation of equipment, and provide an important reference for practical industrial applications.

[0006] In a first aspect, the present invention proposes a method for electromechanical coupling modeling of a gear transmission system, comprising the following steps:

[0007] Step 1: Create a 3D model based on the 3D parameters of the input shaft, output shaft, input gear, and output gear in the actual gearbox; import the 3D model into Ansys Motion and establish a rigid-flexible coupling model of a single-stage fixed-axis gear transmission based on the finite element method. Step 2: Construct a three-phase asynchronous motor model based on Simulink as the drive end of the gear system. By defining a speed-torque closed-loop interface, realize the dynamic coupling between the three-phase asynchronous motor model and the rigid-flexible coupling model of a single-stage fixed-axis gear transmission, and construct an electromechanical coupling model. Step 3: Calculate the frequency domain vibration response signal of the output gear in the rigid-flexible coupling model and the electromechanical coupling model of the single-stage fixed-axis gear transmission, respectively; Step 4: Extract the frequency domain vibration response signals of the output gear under normal and broken tooth fault conditions for comparative analysis, obtain the influence law of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system, and include it in the diagnostic feature library as correction reference data for the next modeling.

[0008] Preferably, the three-dimensional modeling in step one includes: Three-dimensional modeling was completed based on the aforementioned three-dimensional parameters and the involute tooth profile drawing function in SolidWorks software; the four bearings required for transmission were simulated using the equivalent bearings provided by Ansys Motion. Specifically, for the three-dimensional model of tooth breakage, the model is quickly generated by matching the actual gear parameters with standardized fault feature library templates; the standardized fault feature library includes parameterized templates for different degrees and locations of tooth breakage.

[0009] Preferably, the step one, which establishes a rigid-flexible coupling model of a single-stage fixed-axis gear transmission based on the finite element method, includes: Modeling the transmission system: The input gear is fixedly connected to the input shaft, and the output gear is fixedly connected to the output shaft, with binding constraints applied. Rotary pairs are set for the input shaft and output shaft in the ground reference frame, with their positions selected as the spatial centers of the corresponding gears. The tooth surface contact relationship between the transmission gears is established through general contact, and the corresponding contact parameters are set. At the same time, the gear transmission mode is defined through gear coupling, and the finite element simulation settings of the transmission system are completed. Configure the gearbox body: Use the REB Single function in the software to set the coupling, select the four base holes of the gearbox body as the coupling surface, select the origin of the model coordinate system as the coupling point, and then add a Fixed constraint to this coupling setting to complete the fixed constraint of the entire gearbox. The transmission and housing components are coupled: the Easy-Flex simulation software is used to perform modal analysis on the housing component, and the calculation file containing modal information is imported into the housing model, setting the housing as a flexible body; an equivalent bearing model is constructed using the general bearing function, connecting the outer ring of the bearing to the corresponding part of the housing and the inner ring to the transmission shaft, with the axial direction as the rotation direction, and the bearing characteristics are defined by setting the stiffness and damping parameters of the bearing; at the same time, according to the arrangement of sensors in the actual transmission system, the corresponding vibration signal output points are selected in the dynamic model and a reference coordinate system is established to complete the construction of a rigid-flexible coupling model for a single-stage fixed-axis gear transmission.

[0010] Step two, which involves building a three-phase asynchronous motor model based on Simulink, includes: Select the Asynchronous Machine module from the Simulink / Simscape Electrical library and set the key parameters according to the motor nameplate parameters; The Clark transformation is used to transform the three-phase stationary coordinate system. i a , i b and i c Projecting the variables onto the two-phase stationary α-β coordinate system, we obtain... I α and I β； The output of the Clark module I α and I β Input to the Park transform module and then output i d and i q , target speed ω ref and motor feedback speed ωm The error is calculated by comparing the results using an adder and then output through a speed PI controller. q Target value of shaft current i q_ref Complete the velocity loop construction; target value i q_ref Motor feedback i q Difference after calculus q Axis current PI controller output u q ,Finish q Shaft current loop construction; Given excitation current i d_ref Magnetic and feedback i d After comparing and subtracting d Axis current PI controller output u d Finish d Shaft current loop construction; Output u d and u q The three-phase voltage output from the inverse Park transformation module is injected into the Space Vector Generator module in the Simulink / Simscape Electrical library, outputting six PWM pulse signals. The Universal Bridge module is used as the inverter, with IGBT / diode type selected and connected to a DC power supply. The six PWM pulse signals are input into the inverter, and the three-phase voltage output by the inverter drives the asynchronous motor. The three-phase current output by the motor is transformed by Clark / Park and fed back to the current loop, and the output speed is fed back to the speed loop, forming a complete dual closed-loop vector control system. The three-phase asynchronous motor model has been completed.

[0011] Preferably, the dynamic coupling of the three-phase asynchronous motor model and the single-stage fixed-axis gear transmission rigid-flexible coupling model in step two constructs an electromechanical coupling model, specifically including: In Ansys Motion, the external input function of the overall gear transmission simulation model is defined using the SInput function and applied to the input shaft revolute joint as the driving function; the Z-direction vibration signal of the sensor point on the gearbox during gear operation is extracted using the S-Output function and output as an M-File file. Open the M-File in Simulink to obtain the encapsulation block containing the three-dimensional information and constraint information of the overall finite element simulation model; connect the constructed three-phase asynchronous motor model to the encapsulation block to complete the construction of the electromechanical coupling model.

[0012] Preferably, step three specifically includes: Calculate the frequency domain vibration response signal of a rigid-flexible coupling model of a single-stage fixed-axis gear transmission: In Ansys Motion, select the input shaft revolute joint, set its type to Motion Function, use the STEP function to set the input speed, and maintain this speed for 0.1 seconds until the end of the simulation; adjust the analysis step size to make the number of output points consistent with the sampling frequency, start the simulation to obtain the frequency domain vibration response signal; Frequency domain vibration response signal of computer-coupled model: The frequency domain vibration response signal is obtained by starting the simulation calculation in Simulink.

[0013] Preferably, the influence of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system specifically includes: Normal gear state: When the motor is not coupled, the frequency domain vibration response signal only includes the gear meshing frequency and its harmonics; after the motor is coupled, the torque of the gear system changes from steady-state excitation to dynamic excitation.

[0014] Tooth breakage fault state: When the motor is not coupled, the frequency domain vibration response signal contains tooth breakage fault modulation sidebands with meshing frequencies of all orders and full frequency band distribution, and forms an obvious resonance peak at the natural frequency of the gearbox; after coupling the motor, the amplitude of the fault sideband near the natural frequency changes regularly, and this change has a fixed correlation with the motor torque fluctuation frequency.

[0015] Secondly, the present invention also provides a gear transmission system electromechanical coupling simulation system, the simulation system comprising: The 3D modeling module performs 3D modeling based on the 3D parameters of the input shaft, output shaft, input gear, and output gear in the actual gearbox. A rigid-flexible coupling model of a single-stage fixed-axis gear transmission was established by importing the three-dimensional model into Ansys Motion and using the finite element method. The electromechanical coupling model is constructed by using a three-phase asynchronous motor model built in Simulink as the drive end of the gear system. By defining a speed-torque closed-loop interface, the dynamic coupling between the three-phase asynchronous motor model and the rigid-flexible coupling model of a single-stage fixed-axis gear transmission is realized, thus constructing the electromechanical coupling model. The data processing module calculates the frequency domain vibration response signal of the output gear in both the rigid-flexible coupling model and the electromechanical coupling model of a single-stage fixed-axis gear transmission. The diagnostic feature library extracts and compares the frequency domain vibration response signals of the output gear under normal and broken tooth fault conditions. It also obtains the influence law of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system and incorporates it into the diagnostic feature library.

[0016] Thirdly, the present invention also provides an electromechanical coupling simulation model of a gear transmission system, which is constructed using the electromechanical coupling modeling method for a gear transmission system described in the first aspect.

[0017] Fourthly, the present invention also provides an application of the electromechanical coupling simulation model of the gear transmission system as described in the third aspect, for simulating the dynamic operation of the gear transmission system.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes the involute tooth profile drawing function of SolidWorks software in the 3D modeling stage, combined with the precise 3D parameters of key components of the actual gearbox, to achieve accurate replication of the core structure of the transmission system. Simultaneously, in the rigid-flexible coupling model construction, only the gearbox body is set as a flexible body to capture dynamic response, while the other components are set as rigid bodies, balancing simulation accuracy and computational efficiency. Furthermore, through detailed optimizations such as equivalent bearing simulation and REB3 element constraint settings, the risk of model distortion is further reduced, making the constructed model more closely resemble the actual operating conditions of the transmission system.

[0019] This invention constructs a three-phase asynchronous motor model using Simulink and designs a speed-torque closed-loop interface to achieve dynamic coupling between the motor and gear transmission rigid-flexible coupling model, forming a closed-loop system for bidirectional energy interaction. It accurately reproduces the dynamic excitation effect of motor electromagnetic torque fluctuations on the gear transmission system, making the simulation scenario closer to the real-world operating conditions of integrated motor-gear operation in industrial settings. Furthermore, by calculating the frequency domain vibration response signals before and after the coupled motor's normal operation and under broken tooth fault conditions, the additional modulation sideband introduced by the motor drive end can be clearly separated, clarifying its difference from and correlation with gear fault characteristics. This allows the model to flexibly adapt to the parameter adjustment requirements of gearboxes of different specifications, while shortening the simulation cycle and making it more suitable for the needs of large-scale simulation analysis and rapid application in practical engineering. Attached Figure Description

[0020] Figure 1 Three-dimensional models of each component of the gear transmission system; Figure 2 This is a 3D model of the output gear; Figure 3 For gear transmission systems in finite element simulation; Figure 4 Constraint settings in finite element simulation; Figure 5 Diagrams of Clark transform and Park transform; Figure 6 This is an electromechanical coupling model of an electric motor-gear transmission built using Simulink. Figure 7 This is a gear meshing model; Figure 8 This is a comparison of the frequency domain signals of the electromechanical coupling model and the finite element transmission model under normal conditions. Figure 9 A comparison of the frequency domain signals of the electromechanical coupling model and the finite element transmission model under the broken tooth condition; Figure 10 This is a comparison of the frequency domain signals of the electromechanical coupling model and the finite element transmission model under the broken tooth condition. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] Example 1: This invention proposes a method for electromechanical coupling modeling of a gear transmission system, comprising the following steps: Step 1: Create a 3D model based on the 3D parameters of the input shaft, output shaft, input gear, and output gear in the actual gearbox; import the 3D model into Ansys Motion and establish a rigid-flexible coupling model of a single-stage fixed-axis gear transmission based on the finite element method. Step 2: Construct a three-phase asynchronous motor model based on Simulink as the drive end of the gear system. By defining a speed-torque closed-loop interface, realize the dynamic coupling between the three-phase asynchronous motor model and the rigid-flexible coupling model of a single-stage fixed-axis gear transmission, and construct an electromechanical coupling model. Step 3: Calculate the frequency domain vibration response signal of the output gear in the rigid-flexible coupling model and the electromechanical coupling model of the single-stage fixed-axis gear transmission, respectively; Step 4: Extract the frequency domain vibration response signals of the output gear under normal and broken tooth fault conditions for comparative analysis, obtain the influence law of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system, and include it in the diagnostic feature library as correction reference data for the next modeling.

[0023] In this embodiment, the three-dimensional modeling in step one includes: Three-dimensional modeling was completed based on the aforementioned three-dimensional parameters and the involute tooth profile drawing function in SolidWorks software; the four bearings required for transmission were simulated using equivalent bearings provided by Ansys Motion; specifically, such as Figure 1 As shown, firstly, based on the precise three-dimensional parameters of the input shaft, output shaft, input gear, and output gear obtained from the actual gearbox, a three-dimensional geometric model of the transmission system is constructed using SolidWorks software. The three-dimensional modeling of the four bearings used for transmission is omitted; instead, in subsequent simulation calculations, the equivalent bearing (General Bearing) provided by Ansys Motion is used to simulate the transmission effect of the bearings. This simplification significantly reduces the complexity of the model while ensuring a certain level of accuracy in the calculation results. For example, in this embodiment, as... Figure 2 As shown in Figure 2, in this embodiment, the input gear has 24 teeth, the output gear has 56 teeth, the module is 2 mm, the pressure angle is 20°, and the input shaft and output shaft are stepped shafts with specific diameters and lengths. The input shaft has a diameter of 25 mm and a length of 180 mm, and the output shaft has a diameter of 35 mm and a length of 220 mm. The transmission gear accurately reproduces the meshing tooth structure of the gear by using the above three-dimensional parameters and the modeling method of drawing involute tooth profiles in SolidWorks software.

[0024] Among them, such as Figure 2 As shown, for the three-dimensional model of tooth breakage fault, the model is quickly generated by matching the actual gear parameters by calling the standardized fault feature library template. The standardized fault feature library includes parameterized templates for different degrees of tooth breakage (such as 1 / 4 tooth breakage, 1 / 2 tooth breakage, and complete tooth breakage) and tooth breakage locations (such as the tooth tip region, tooth root region, and tooth surface middle region). In this embodiment, the template of complete tooth breakage type is selected, and the core parameters such as the number of teeth, module, and pressure angle of the input gear and the output gear are matched to automatically generate a three-dimensional model of a single tooth complete tooth breakage fault of the output gear.

[0025] Preferred, such as Figure 3-4As shown, the complete 3D model is imported into the Ansys Motion multibody dynamics simulation environment, and a rigid-flexible coupling model of a single-stage fixed-axis gear transmission is established using the finite element method. Ansys Motion / Preprocessor software is opened to create a new model file, with MMKS units selected, and the constructed 3D gearbox model is imported. To further simplify the model complexity, improve computational efficiency, and enhance balance accuracy, a rigid-flexible coupling single-stage gear transmission system model is constructed using Ansys Motion based on multibody dynamics theory. In this model, only the gearbox body is considered a flexible body, and its modal flexibility is processed using the software's Easy-Flex technology to accurately capture the structural dynamic response. Other components such as gears and drive shafts are considered rigid bodies to reduce model complexity and computational resource consumption. Specific constraint settings are as follows: Modeling the transmission system: The input gear is fixedly connected to the input shaft, and the output gear is fixedly connected to the output shaft, with binding constraints applied. Rotary pairs are set for the input shaft and output shaft in the ground reference frame, with their positions selected as the spatial centers of the corresponding gears. The tooth surface contact relationship between the transmission gears is established through general contact, and the corresponding contact parameters are set. At the same time, the gear transmission mode is defined through gear coupling, and the finite element simulation settings of the transmission system are completed. The gearbox housing is configured as follows: The REB Single function in the software is used for coupling settings. The coupling surfaces are selected from the four base holes of the gearbox housing, and the coupling points are selected from the origin of the model coordinate system. A Fixed constraint is then applied to this coupling setting to complete the fixation constraint on the entire gearbox. The four bearing seats of the gearbox housing are selected as coupling surfaces, and the coupling points are the spatial centers of their respective bearings. Since the use of REB2 elements introduces additional stiffness, all REB elements described above are replaced with REB3 elements.

[0026] The transmission and gearbox components are coupled: the Easy-Flex simulation software is used to perform modal analysis on the gearbox component. During the analysis, the modal order is set to the first 20 to fully capture the dynamic characteristics of the gearbox within the operating frequency range. After the solution is completed, a calculation file (.mnf format) containing modal information such as natural frequencies and mode shapes is exported. This file is then imported into the gearbox model, and the system automatically switches the gearbox from rigid body properties to flexible body properties to ensure accurate simulation of the elastic deformation and vibration response of the gearbox under actual working conditions.

[0027] An equivalent bearing model is constructed using the General Bearing function. The outer ring of the bearing is connected to the corresponding part of the housing, and the inner ring is connected to the drive shaft. Specifically, the General Bearing function module built into Ansys Motion is called. Based on the bearing model parameters in the actual transmission system (a deep groove ball bearing 6205 is selected in this embodiment), the bearing characteristics are defined by setting the bearing stiffness and damping parameters. Preferably, the radial stiffness of the bearing is set to 3×10. 6 N / m, axial stiffness of 5×10 6 N / m, radial damping is 300 N s / m, axial damping is 400 N s / m; Through the component association function of the software, the outer ring of the bearing is fixedly connected to the preset bearing housing mounting surface on the gearbox, and the inner ring of the bearing is fixedly connected to the shoulder of the input shaft and the output shaft. The rotation direction of the bearing is clearly defined as axial, which is consistent with the direction of rotation of the gear transmission (clockwise), thereby accurately reproducing the supporting and transmitting function of the bearing. Meanwhile, referring to the sensor arrangement scheme in actual industrial equipment, one vibration signal output point (marked as Marker_1 and Marker_2) was selected above the front bearing seat and on the side of the rear bearing seat of the gearbox. The deviation between the output point position and the actual sensor mounting hole position does not exceed ±0.5 mm. A rectangular coordinate system was established with the geometric center of the gearbox as the origin, where the X-axis is along the input shaft axis, the Y-axis is perpendicular to the bottom surface of the gearbox and upward, and the Z-axis is perpendicular to the X-axis in the horizontal direction. The vibration signal output direction is set to the Z-axis direction (vertical direction) to ensure the consistency between the collected vibration signal and the actual monitoring data. Finally, the integrity of the transmission part, the gearbox part and the coupling relationship were checked through the constraint verification function of the software. After confirming that there were no constraint conflicts, component interference and other problems, the rigid-flexible coupling model of the single-stage fixed-axis gear transmission was completed.

[0028] It should be noted that, in constructing the motor model, the three-phase time-varying AC quantities directly controlled and fed into the three-phase stator windings are... i a , i b and i c This is extremely difficult, as decoupling is challenging and the vector direction changes are complex. To establish a mathematical model suitable for dynamic simulation of electromechanical coupling, this invention uses a dq-axis equivalent circuit to establish a motor model under ideal conditions, converting the three-phase time-varying AC quantities into... i d and i q Direct flow.

[0029] The specific implementation method for constructing a three-phase asynchronous motor model based on Simulink in step two is as follows: Clark transformation is used to transform the three-phase stationary coordinate system... i a , i b and i c Projecting the variables onto the two-phase stationary α-β coordinate system, we obtain... I α and I β The specific Clark conversion formula is shown below. This formula can be directly written and encapsulated using the Fcn module, and the three-phase current output by the motor can be input into the Clark conversion module.

[0030] ; Next, we will build the Park transform module, and then perform the Park transform... α - β Variable transformation in coordinate system to two-phase rotation d - q In the coordinate system, the specific Park transformation formula is shown below. This formula can also be directly written and encapsulated using the Fcn module, as follows: Figure 5 As shown, the output of the Clark module I α and I β Input to the Park transform module and then output i d and i q .

[0031] ; After completing the above two modules, the target rotational speed will be... ω ref and motor feedback speed ω m The error is calculated by comparing the results using an adder and then output through a speed PI controller. q Target value of shaft current i q_ref Complete the velocity loop construction.

[0032] target value i q_ref Motor feedback i q Difference after calculus q Axis current PI controller output u q ,Finish q Shaft current loop construction; Given excitation currenti d_ref Magnetic and feedback i d After comparing and subtracting d Axis current PI controller output u d Finish d Shaft current loop construction; Output u d and u q The three-phase voltage output from the inverse Park transformation module is injected into the Space Vector Generator module in the Simulink / Simscape Electrical library, outputting six PWM pulse signals. The Universal Bridge module is used as the inverter, with IGBT / diode type selected and connected to a DC power supply. The six PWM pulse signals are input into the inverter, and the three-phase voltage output by the inverter drives the asynchronous motor. The three-phase current output by the motor is transformed by Clark / Park and fed back to the current loop, and the output speed is fed back to the speed loop, forming a complete dual closed-loop vector control system. At this point, the three-phase asynchronous motor model has been completed, resulting in a motor-gear transmission electromechanical coupling model built in Simulink.

[0033] Furthermore, the electromechanical coupling model is constructed by defining a speed-torque closed-loop interface. From the perspective of energy conversion, the energy transfer between the motor and gear system is that the motor consumes electrical energy to ultimately generate mechanical energy, and the mechanical system absorbs kinetic energy to ultimately consume electrical energy.

[0034] Specifically, the electromagnetic torque signal output by the three-phase asynchronous motor model is applied as a driving load to the input shaft of the gear transmission finite element model; simultaneously, the output speed signal of the gear transmission finite element model under load is fed back to the control system of the three-phase asynchronous motor model as its load input. Thus, the electrical dynamic characteristics of the motor side and the mechanical dynamic characteristics of the gear transmission side influence each other, forming a closed-loop system of bidirectional energy interaction, which can accurately simulate the electromechanical coupling effect between the motor drive end and the gearbox under actual working conditions.

[0035] In this embodiment, the dynamic coupling of the three-phase asynchronous motor model and the rigid-flexible coupling model of the single-stage fixed-axis gear transmission in step two constructs an electromechanical coupling model. Specifically, this includes: the electromagnetic torque signal output by the three-phase asynchronous motor model is applied as a driving load to the input shaft of the gear transmission finite element model; simultaneously, the output speed signal of the gear transmission finite element model under load is fed back to the control system of the three-phase asynchronous motor model as its load input. Thus, the electrical dynamic characteristics of the motor side and the mechanical dynamic characteristics of the gear transmission side influence each other, forming a closed-loop system of bidirectional energy interaction, which can accurately simulate the electromechanical coupling effect between the motor drive end and the gearbox under actual working conditions. The specific implementation method is as follows: In Ansys Motion, the external input function of the overall gear transmission simulation model is defined through the SInput function, and it is applied to the input shaft revolute joint as the driving function; the vibration signal in the Z direction of the sensor point on the gearbox during gear operation is extracted through the S-Output function, and ACCZ(Marker_1) is selected in the function library to specify the required coordinate system to extract the output signal in the Z direction; after the settings are completed, the M-File is output using the Co-Simulator function item built into the software; Open the M-File in Simulink to obtain the encapsulated block containing the 3D information and constraint information of the overall finite element simulation model; connect the constructed three-phase asynchronous motor model to this encapsulated block to complete the electromechanical coupling model construction, as shown below. Figure 6 As shown.

[0036] Preferably, the calculation principles of the finite element simulation model and electromechanical coupling simulation model in step three are as follows, specifically including: To calculate the frequency domain vibration response signal of a rigid-flexible coupling model of a single-stage fixed-axis gear transmission: In Ansys Motion, select the input shaft revolute joint, set its type to Motion Function, and set the input speed by setting the step function - STEP function. It is worth noting that the speed unit in Ansys Motion is rad / T, so you need to convert the unit yourself before setting it. The specific function is STEP(TIME,x1,x2,x3,x4), which means that time is used as the reference unit for variable change. The speed changes from 0 rad / T to x4 rad / T within the time interval 0-x3 s, and then maintains this speed for the set simulation duration after x3 s. The analysis step size is adjusted to make the number of output points consistent with the sampling frequency, and the simulation calculation is started to obtain the frequency domain vibration response signal. Preferably, in this example, the STEP function is STEP(TIME,0,0,0.1,83.77580), the speed changes from 0 rad / T to 83.77580 rad / T (800RPM) within the time interval 0-0.1 seconds, and maintains this speed for the set simulation duration after 0.1 seconds, thus completing the gear transmission power level setting. In the Simulation module, set the simulation duration to 11 seconds and the sampling frequency to 40000Hz. At the same time, it is necessary to set the analysis step size to ensure that the number of output points is consistent with the set sampling frequency. Thus, the simulation calculation of the dynamic model of the single-stage fixed-axis gear transmission system is completed.

[0037] Frequency domain vibration response signal of the computer-coupled model: As in the example above, after setting up the dynamic model of the single-stage fixed-axis gear transmission system, the three-phase asynchronous motor model is connected to the package block. Then, in Simulink, the simulation duration is set to 11 seconds (which needs to be consistent with Ansys), and the analysis step size is set to 2.5 × 10⁻⁶. -5 Simulation calculations were performed using a fixed step size, thus completing the simulation calculations for the electromechanical coupling model.

[0038] Preferably, the influence of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system specifically includes: performing frequency domain comparative analysis on the frequency domain vibration response signal. The analysis revealed that after coupling the motor, modulation sidebands appeared in the spectrum, spaced at intervals of the motor's electromagnetic torque fluctuation frequency, as shown in the attached figure. Figure 8 As shown, this is due to the introduction of dynamic excitation rather than steady-state excitation by the motor as the driving end. The vibration response of the gear transmission system is mainly affected by the meshing stiffness and external excitation. When the motor is used as the driving end, the electromagnetic torque of the motor... Te Instead of being a constant value, it fluctuates over time, which causes the torque input to the gear system to become a dynamic excitation.

[0039] When the finite element simulation model is coupled with the motor, an additional modulation frequency is introduced into the gear vibration response spectrum signal. The principle is that although there are many transmission components in a fixed-axis gear transmission system, the main part is gear transmission, and the overall dynamic vibration is mainly generated by the meshing of the transmission gears. Under steady-speed conditions, the single-stage fixed-axis gear meshing model can be simplified as shown in the attached figure. Figure 7 As shown. Among them, r 1 and r 2 represents the base circle radii of the input gear and the output gear, respectively. n 1 and n 2 represents the rotational speeds of the input gear and the output gear, respectively. T 1 and T 2 represents the torque acting on the two gears respectively; k ( t () represents the time-varying nonlinear meshing stiffness in the direction of the meshing line, which is the main source of excitation for the overall transmission system; C For the meshing damping of the gear pair; e ( t ) is a stationary displacement error function, which is the error between the actual meshing point and the theoretical meshing point of the gear caused by the fault; x 1( t ), x 2( t The input and output gears are respectively displaced along the line of meshing. The dynamic equations at their meshing points are: ; In the formula, x ( t The value represents the relative displacement of the gears along the line of meshing. x ( t ) = x 1( t )- x 2( t ), M For equivalent mass, E This represents the average elastic deformation of the gear after being subjected to a load; F represents the excitation exerted on the gear transmission system by the external load during normal operation, specifically equal to... F 0= T / R , f im ( tThe force is the impact-type fault excitation force, and the pulse sequence is the force generated when the gear passes through the fault point. From the dynamic model of the gear meshing point, it can be seen that external loads have a significant impact on the dynamic characteristics of the gear meshing point, and the excitation generated by gear meshing is the main source of the dynamic vibration response of the overall gear transmission system. Therefore, it is inferred that external loads have a non-negligible influence on the vibration response of the overall gear transmission system. Under normal meshing conditions, e ( t )and f im ( t Since both are 0, the dynamic equation at the meshing point can be further simplified to: ; In the formula, the left side represents the linear system, and the right side represents the excitation force. x ( t ) k 1( t The term ) represents a nonlinear term, which makes it difficult to obtain an exact solution to the equation. Based on the frequency preservation property of linear systems, the above equation can be further decomposed into a linear excitation component and a nonlinear excitation component.

[0040] ; ; Linear excitation force -Ek 1( t Due to time-varying meshing stiffness k 1( t The periodic variation of the excitation force produces a response frequency that is the meshing frequency and its higher-order harmonics. For the nonlinear coupling term, the excitation force... x ( t ) k 1( t ), by vibration response x ( t ) and stiffness k 1( t The product of time domain products and frequency domain products. By the principle that time domain product equals frequency domain convolution, we can obtain... x ( t ) spectrum and k 1( t Convolving the spectrum of the motor with the frequency of gears yields an integer multiple harmonic of the meshing frequency. Therefore, the total response spectrum under normal conditions before coupling the motor exhibits a clear amplitude spectrum containing only the meshing frequency and its harmonics. Previous studies based on the lumped parameter method defined the input torque as a steady-state excitation, assigning it a constant and neglecting it. However, in reality, changes in the electrical characteristics of the motor can affect the gear transmission.

[0041] Coupled with a finite element simulation model, torque fluctuations are introduced at the input. This is because when a motor acts as a drive source, its output electromagnetic torque is not absolutely constant but exhibits inherent fluctuations. These fluctuations mainly originate from the motor's inherent characteristics, such as cogging effect, magnetic field distortion, and current harmonics, and their frequency is usually related to the motor's rotational frequency or its harmonics. In this case, the input torque... T in ( t ) is a time variable, specifically: T in ( t ) = T+ΔT ( t ),in T For average torque, ΔT ( t ) represents the torque ripple component. ΔT ( t The motivation generated F mT Vibration response of gear transmission system x ( t Coupling occurs, generating new nonlinear terms. F mT k 1( t After convolution, the two signals ultimately produce a modulated signal in the vibration spectrum. This manifests as a spectral structure modulated by torque fluctuations appearing on both sides of the meshing frequency in the original spectrum calculated by the finite element simulation model, as shown in the attached figure. Figure 8 The electromechanical coupling model shown exhibits additional sidebands such as 87.3 Hz and 116.4 Hz in its spectrum.

[0042] When a broken tooth exists on the gear, a significant impact phenomenon occurs in the time domain, with intervals equal to the reciprocal of the output gear's rotational frequency. The main frequency components are the meshing frequencies, modulation sidebands distributed across the entire frequency band due to the broken tooth fault, and resonance peaks formed by modulation from the flexible housing. To further analyze the impact of the coupled motor on the vibration response of the gear transmission system, the vibration response simulation results of the finite element gear transmission dynamics model under broken tooth fault are compared with the locally enlarged simulation results of the motor-gear transmission system, as shown in the attached figure. Figure 9-10 As shown. The main frequency components are the gear meshing frequency and its harmonics. At the natural frequency of the flexible gearbox, the amplitude of the modulation sideband caused by the broken tooth fault is excited to form a resonance peak. The main frequency characteristics are no different from the finite element simulation results. The spectrum contains modulation sidebands spaced at the rotational frequency of the faulty gear, and a resonance peak is formed near the natural frequency. Since the fault itself has introduced a large number of modulation sidebands spaced at rotational frequencies, the modulation sidebands caused by the electromagnetic torque fluctuation of the motor are partially masked, but the coupled model can still reflect them. ΔT ( tThe modulation effect on the resonant band, such as the change in the amplitude of the sideband near the natural frequency.

[0043] In summary, from the perspective of gear transmission mechanism, it is clear that when the motor acts as the driving end, the external excitation of the gear transmission system is no longer a static excitation, but a dynamic excitation influenced by the electromagnetic torque of the motor. The additional frequency components in the spectrum are modulation sidebands caused by the electromagnetic torque of the motor. This analytical principle provides new technical support for improving the accuracy of fault diagnosis and condition monitoring of gear transmission systems. In other words, the influence of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system includes: Normal gear state: When the motor is not coupled, the frequency domain vibration response signal only contains the gear meshing frequency and its various harmonics; After coupling the motor, the torque of the gear system changes from steady-state excitation to dynamic excitation. Broken tooth fault state: When the motor is not coupled, the frequency domain vibration response signal contains the meshing frequencies of various orders and the broken tooth fault modulation sideband distributed throughout the frequency band, and forms a significant resonance peak at the natural frequency of the gearbox; After coupling the motor, the amplitude of the fault sideband near the natural frequency changes regularly, and this change has a fixed correlation with the motor torque fluctuation frequency.

[0044] This invention utilizes the finite element method to establish a gear transmission model, improving the accuracy and reliability of the model. This makes the constructed model closer to the actual transmission system, enhancing the accuracy and reliability of fault diagnosis and providing an important reference for maintaining equipment safety in practical industrial applications.

[0045] This invention starts with the frequency signal of the signal to explore the additional modulation sideband residue caused by the electromechanical coupling model, thereby clarifying the impact of the motor as the driving end on the vibration response of the gear transmission system, improving the accuracy of fault diagnosis, ensuring the safe operation of equipment, and improving the actual industrial economic benefits.

[0046] Example 2: The present invention also provides a gear transmission system electromechanical coupling simulation system, the simulation system comprising: The 3D modeling module performs 3D modeling based on the 3D parameters of the input shaft, output shaft, input gear, and output gear in the actual gearbox. A rigid-flexible coupling model of a single-stage fixed-axis gear transmission was established by importing the three-dimensional model into Ansys Motion and using the finite element method. The electromechanical coupling model is constructed by using a three-phase asynchronous motor model built in Simulink as the drive end of the gear system. By defining a speed-torque closed-loop interface, the dynamic coupling between the three-phase asynchronous motor model and the rigid-flexible coupling model of a single-stage fixed-axis gear transmission is realized, thus constructing the electromechanical coupling model. The data processing module calculates the frequency domain vibration response signal of the output gear in both the rigid-flexible coupling model and the electromechanical coupling model of a single-stage fixed-axis gear transmission. The diagnostic feature library extracts and compares the frequency domain vibration response signals of the output gear under normal and broken tooth fault conditions. It also obtains the influence law of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system and incorporates it into the diagnostic feature library.

[0047] In Example 3, the present invention also provides an electromechanical coupling simulation model of a gear transmission system, which is constructed using the electromechanical coupling modeling method for a gear transmission system described in the first aspect.

[0048] Example 4: The present invention also provides an application of the electromechanical coupling simulation model of the gear transmission system as described in the third aspect, for simulating the dynamic operation of the gear transmission system.

[0049] Preferably, the application examples of the electromechanical coupling simulation model of the gear transmission system of the present invention are as follows: Machine tool spindle transmission system simulation: Applied to CNC lathe spindle transmission scenarios, the model simulates the dynamic operation of the spindle gear under motor drive during normal meshing and tooth breakage faults, and outputs data such as speed fluctuation, meshing vibration, and electromagnetic torque changes, providing simulation support for debugging machine tool spindle fault early warning algorithms.

[0050] Wind turbine gearbox operation simulation: For small wind turbine gear transmission systems, the model is used to reproduce the coordinated operation of the motor and gearbox under different wind speeds, analyze the impact of motor torque fluctuations on gear meshing losses, and guide the structural optimization design of wind turbine gearboxes, but is not limited to this.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the statement "comprising a…" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0052] Although the description of the invention has been given in conjunction with the specific embodiments described above, it will be apparent to those skilled in the art that many substitutions, modifications, and variations can be made based on the foregoing. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. A method for electromechanical coupling modeling of a gear transmission system, characterized in that, Includes the following steps: Step 1: Create a 3D model based on the 3D parameters of the input shaft, output shaft, input gear, and output gear in the actual gearbox; Import the 3D model into Ansys Motion and establish a rigid-flexible coupling model of a single-stage fixed-axis gear transmission based on the finite element method. Step 2: Construct a three-phase asynchronous motor model based on Simulink as the drive end of the gear system. By defining a speed-torque closed-loop interface, realize the dynamic coupling between the three-phase asynchronous motor model and the rigid-flexible coupling model of a single-stage fixed-axis gear transmission, and construct an electromechanical coupling model. Step 3: Calculate the frequency domain vibration response signal of the output gear in the rigid-flexible coupling model and the electromechanical coupling model of the single-stage fixed-axis gear transmission, respectively; Step 4: Extract the frequency domain vibration response signals of the output gear under normal and broken tooth fault conditions for comparative analysis, obtain the influence law of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system, and include it in the diagnostic feature library as correction reference data for the next modeling.

2. The electromechanical coupling modeling method for a gear transmission system according to claim 1, characterized in that, The three-dimensional modeling in step one includes: The three-dimensional model was completed based on the aforementioned three-dimensional parameters and the involute tooth profile drawing function in SolidWorks software; the four bearings required for transmission were simulated using the equivalent bearings provided by Ansys Motion. Specifically, for the three-dimensional model of tooth breakage, the model is quickly generated by matching the actual gear parameters with standardized fault feature library templates; the standardized fault feature library includes parameterized templates for different degrees and locations of tooth breakage.

3. The electromechanical coupling modeling method for a gear transmission system according to claim 2, characterized in that, Step one, which establishes a rigid-flexible coupling model of a single-stage fixed-axis gear transmission based on the finite element method, includes: Modeling the transmission system: The input gear is fixedly connected to the input shaft, and the output gear is fixedly connected to the output shaft, with binding constraints applied. Rotary pairs are set for the input shaft and output shaft in the ground reference frame, with their positions selected as the spatial centers of the corresponding gears. The tooth surface contact relationship between the transmission gears is established through general contact, and the corresponding contact parameters are set. At the same time, the gear transmission mode is defined through gear coupling, and the finite element simulation settings of the transmission system are completed. Configure the gearbox body: Use the REB Single function in the software to set the coupling, select the four base holes of the gearbox body as the coupling surface, select the origin of the model coordinate system as the coupling point, and then add a Fixed constraint to this coupling setting to complete the fixed constraint of the entire gearbox. The transmission and housing components are coupled: the Easy-Flex simulation software is used to perform modal analysis on the housing component, and the calculation file containing modal information is imported into the housing model, setting the housing as a flexible body; an equivalent bearing model is constructed using the general bearing function, connecting the outer ring of the bearing to the corresponding part of the housing and the inner ring to the transmission shaft, with the axial direction as the rotation direction, and the bearing characteristics are defined by setting the stiffness and damping parameters of the bearing; at the same time, according to the arrangement of sensors in the actual transmission system, the corresponding vibration signal output points are selected in the dynamic model and a reference coordinate system is established to complete the construction of a rigid-flexible coupling model for a single-stage fixed-axis gear transmission.

4. The electromechanical coupling modeling method for a gear transmission system according to claim 3, characterized in that, Step two, which involves building a three-phase asynchronous motor model based on Simulink, includes: Select the Asynchronous Machine module from the Simulink / Simscape Electrical library and set the key parameters according to the motor nameplate parameters; The Clark transformation is used to transform the three-phase stationary coordinate system. i a , i b and i c Projecting the variables onto the two-phase stationary α-β coordinate system, we obtain... I α and I β； The output of the Clark module I α and I β Input to the Park transform module and then output i d and i q , target speed ω ref and motor feedback speed ω m The error is calculated by comparing the values ​​using an adder and then output through a speed PI controller. q Target value of shaft current i q_ref Complete the velocity loop construction; target value i q_ref Motor feedback i q Difference after calculus q Axis current PI controller output u q ,Finish q Shaft current loop construction; Given excitation current i d_ref Magnetic and feedback i d After comparing and subtracting d Axis current PI controller output u d Finish d Shaft current loop construction; Output u d and u q The three-phase voltage output from the inverse Park transformation module is injected into the Space Vector Generator module in the Simulink / SimscapeElectrical library, outputting six PWM pulse signals. The Universal Bridge module is used as the inverter, with IGBT / diode type selected and connected to a DC power supply. The six PWM pulse signals are input into the inverter, and the three-phase voltage output by the inverter drives the asynchronous motor. The three-phase current output by the motor is transformed by Clark / Park and fed back to the current loop, and the output speed is fed back to the speed loop, forming a complete dual closed-loop vector control system. The three-phase asynchronous motor model has been completed.

5. The electromechanical coupling modeling method for a gear transmission system according to claim 4, characterized in that, The dynamic coupling of the three-phase asynchronous motor model and the single-stage fixed-axis gear transmission rigid-flexible coupling model in step two constructs an electromechanical coupling model, specifically including: In Ansys Motion, the external input function of the overall gear transmission simulation model is defined using the SInput function and applied to the input shaft revolute joint as the driving function; the Z-direction vibration signal of the sensor point on the gearbox during gear operation is extracted using the S-Output function and output as an M-File file. Open the M-File in Simulink to obtain the encapsulation block containing the three-dimensional information and constraint information of the overall finite element simulation model; connect the constructed three-phase asynchronous motor model to the encapsulation block to complete the construction of the electromechanical coupling model.

6. The electromechanical coupling modeling method for a gear transmission system according to claim 5, characterized in that, Step three specifically includes: To calculate the frequency domain vibration response signal of a rigid-flexible coupling model of a single-stage fixed-axis gear transmission: In Ansys Motion, select the input shaft revolute joint, set its type to Motion Function, use the STEP function to set the input speed, and maintain this speed for 0.1 seconds until the end of the simulation; adjust the analysis step size to make the number of output points consistent with the sampling frequency, and start the simulation to obtain the frequency domain vibration response signal; Frequency domain vibration response signal of computer-coupled model: The frequency domain vibration response signal is obtained by starting the simulation calculation in Simulink.

7. The electromechanical coupling modeling method for a gear transmission system according to claim 6, characterized in that, The influence of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system specifically includes: Normal gear state: When the motor is not coupled, the frequency domain vibration response signal only includes the gear meshing frequency and its harmonics; after the motor is coupled, the torque of the gear system changes from steady-state excitation to dynamic excitation. Tooth breakage fault state: When the motor is not coupled, the frequency domain vibration response signal contains tooth breakage fault modulation sidebands with meshing frequencies of all orders and full frequency band distribution, and forms an obvious resonance peak at the natural frequency of the gearbox; after coupling the motor, the amplitude of the fault sideband near the natural frequency changes regularly, and this change has a fixed correlation with the motor torque fluctuation frequency.

8. A gear transmission system electromechanical coupling simulation system, characterized in that, The simulation system includes: The 3D modeling module performs 3D modeling based on the 3D parameters of the input shaft, output shaft, input gear, and output gear in the actual gearbox. A rigid-flexible coupling model of a single-stage fixed-axis gear transmission was established by importing the three-dimensional model into Ansys Motion and using the finite element method. The electromechanical coupling model is constructed by using a three-phase asynchronous motor model built in Simulink as the drive end of the gear system. By defining a speed-torque closed-loop interface, the dynamic coupling between the three-phase asynchronous motor model and the rigid-flexible coupling model of a single-stage fixed-axis gear transmission is realized, thus constructing the electromechanical coupling model. The data processing module calculates the frequency domain vibration response signal of the output gear in both the rigid-flexible coupling model and the electromechanical coupling model of a single-stage fixed-axis gear transmission. The diagnostic feature library extracts and compares the frequency domain vibration response signals of the output gear under normal and broken tooth fault conditions. It also obtains the influence law of the three-phase asynchronous motor model as the driving end on the frequency domain vibration response signal of the gear transmission system and incorporates it into the diagnostic feature library.

9. A simulation model of electromechanical coupling in a gear transmission system, characterized in that, The model is constructed using the electromechanical coupling modeling method for a gear transmission system as described in any one of claims 1-7.

10. The application of the electromechanical coupling simulation model of the gear transmission system as described in claim 9, characterized in that, Used to simulate the dynamic operation of gear transmission systems.

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