Irregular wheel wear detection method based on stator current analysis

Abstract

The invention relates to the technical field of railway electric traction transmission, in particular to an irregular wheel wear detection method based on stator current analysis, which comprises the following steps of: constructing an electromechanical coupling model of a high-speed train traction transmission system based on a traction variable-current driving model and a train-track coupling power model; secondly, based on an electromechanical coupling model, the influence of irregular wear of the wheel on electrical parameters in an electric driving system is analyzed, and the frequency relation between irregular wear excitation and the electrical parameters (stator harmonic current) is established; and by constructing a comb filter based on variable mode decomposition, accurate capture of wheel wear related harmonic waves in stator current is realized, so that irregular wear of the wheel is detected, additional installation of a sensor is not needed, the cost is low, the method is not liable to be interfered by the external environment, and the method has relatively good engineering applicability.

Description

Technical Field

[0001] This invention relates to the field of railway electric traction transmission technology, and in particular to a method for detecting irregular wheel wear based on stator current analysis. Background Technology

[0002] With the continuous increase in high-speed railway operating speeds, wheels need to withstand greater impact loads. In recent years, irregular wheel wear has gradually become a serious challenge for rail vehicles, with polygonal wear and wheel flat spots being the most prominent. Irregular wheel wear not only exacerbates the vibration and impact of the wheel-rail system, leading to accelerated fatigue aging of key components, but may also seriously threaten operational safety at higher speeds. Therefore, timely and accurate monitoring of wheel wear and implementation of corresponding maintenance measures will help reduce the risk of failure, extend vehicle service life, and ensure the safe and stable operation of high-speed railways.

[0003] Commonly used wheel wear monitoring methods are mostly based on the direct or indirect analysis of mechanical vibration signals (such as vertical axle box acceleration (ABA) signals). However, in the process of developing this invention, the applicant discovered that the acquisition of mechanical vibration signals is easily affected by complex external environments, leading to a decrease in the stability and reliability of monitoring results. Meanwhile, while some AI-based monitoring methods possess a certain degree of intelligent recognition capability, they are often highly dependent on training data, difficult to generalize to unseen scenarios, and lack physical interpretability. This makes it difficult for existing technologies to effectively monitor irregular wheel wear conditions. Summary of the Invention

[0004] The purpose of this application is to provide a method for detecting irregular wheel wear based on stator current analysis, thereby solving the aforementioned technical problems in the prior art.

[0005] This application is implemented as follows: This application provides a method for detecting irregular wheel wear based on stator current analysis, used to detect irregular wear on train wheels, characterized by the following steps: Step S100: Establish the traction converter drive system model and the train-track coupled dynamics model of the train, and integrate the traction converter drive system model and the train-track coupled dynamics model. Based on the input / output relationship between the electrical side and the mechanical side, construct a closed-loop feedback mechanism to form an electromechanical coupling model of the traction drive system. Step S200: Based on the electromechanical coupling model, obtain the time-frequency characteristics of electrical and mechanical parameters in the traction transmission system under irregular wheel wear excitation. The electrical parameters include stator current; the mechanical parameters include wheelset vibration acceleration, wheel-rail normal force, and rotor speed. Establish the mathematical relationship between irregular wheel wear and stator harmonic current. in, The frequency of the harmonic current; This is the motor's base frequency; Let n be the excitation frequency for irregular wear of the wheel, where n is a positive integer; In step S300, the harmonic components generated by irregular wear excitation are separated from the stator current by a comb filter to detect irregular wear of the wheel.

[0006] Furthermore, the traction converter drive system model includes a rectifier, an intermediate DC link, an inverter, and a traction motor; the train-track coupled dynamics model includes a train subsystem, a track subsystem, and a wheel-rail coupling subsystem.

[0007] Furthermore, a traction converter drive system model was built in MATLAB / Simulink, and a train-track coupled dynamics model was constructed in the commercial multibody dynamics software SIMPACK. The train-track coupled dynamics model includes vehicle dynamics models of the car body, two bogies, four wheelsets, four gearboxes, and four motors. The wheelset is modeled as a flexible body, and its modeling and modal analysis are performed in Ansys / APDL. Mode shapes of orders 7 to 25, with a frequency range covering up to 1000 Hz, are selected and imported into the vehicle dynamics model. The motor-gear transmission model includes a stator, rotor, drive gear, and driven gear. The track simulation is a dual-mass (sleeper-track bed) spring-damped model; The rail is simulated as an infinitely long Timoshenko beam supported by continuously elastic discrete points. The wheel-rail coupling subsystem is implemented through normal contact modeling and tangential contact modeling. The normal contact modeling is based on Hertz nonlinear elastic contact theory and is expressed as follows: (1) in For the wheel-rail normal force; The wheel-rail contact constant; It is the elastic compression between the wheel and the rail, which is determined by the vertical displacement of the wheel and the rail at the wheel-rail contact point; The tangential contact modeling is implemented using simplified Kalker theory to solve for the tangential stress generated by wheel-rail interaction, which can be expressed as follows: (2) in and These are the tangential stresses in the x (longitudinal) and y (lateral) directions, respectively. , and These are longitudinal, transverse, and spin creep rates, respectively. , and These are the longitudinal, transverse, and spin compliance coefficients, respectively, where a0 is the longitudinal coordinate of the particle with transverse coordinate y0 at the leading edge of the contact patch; Using the SIMAT interface between MATLAB and SIMPACK, the established traction converter drive system model and the train-track coupled dynamics model are integrated into the same simulation environment, and the traction converter drive system model is used to realize real-time control of the train-track coupled dynamics model.

[0008] Furthermore, the driving torque output by the traction converter drive system model is transmitted to the train-track coupled dynamics model via SIMAT and applied to the motor rotor; at the same time, the mechanical angular velocity of the motor rotor is fed back to the motor control module of the electric traction converter drive system model via SIMAT. Through the above bidirectional transmission, closed-loop feedback and real-time interaction between the traction converter drive system model and the train-track coupled dynamics model are realized.

[0009] Further, in step S200, the time-frequency characteristics of electrical and mechanical parameters in the traction transmission system under irregular wheel wear excitation are obtained by including the following steps, and a mathematical relationship between irregular wheel wear and stator harmonic current is established: Step S210: Irregular wheel wear is introduced into the train-track coupled dynamics model in the form of radius deviation. This irregular wear includes wheel flat spots and polygonal wheel wear. The excitation frequency corresponding to the wheel wear is then calculated as follows: in, The train's operating speed; The radius of the wheel; The wear order of the polygonal wheel; Step S220: Run the electromechanical coupling model. The output of the train-track coupled dynamics model includes wheelset vibration acceleration. ), wheel-rail normal force ( ) and rotor speed ( The mechanical parameters of the output mechanical parameters are analyzed by spectrum analysis and compared with those in formula (3). Perform corresponding matching to identify the transmission path and pattern of wheel wear excitation in the mechanical transmission system; Step S230: Extract key electrical parameters, including d-axis and q-axis currents and stator currents, from the motor control module; perform spectrum analysis on the extracted key electrical parameters, and establish a mapping relationship between wheel wear excitation and stator current based on rotor speed fluctuations, specifically including: Step S231, in the motor control module, the torque command value calculated based on the speed sub-fluctuation can be expressed as: (4) in, express The excitation angular frequency of the polygonal wheel. and These are the proportional and integral coefficients in the speed regulation module. This is the torque command value; ω r and These are the actual and set values ​​of the rotor speed, respectively. and The amplitude and phase of the torque command value fluctuation; Step S232: Calculate the d-axis and q-axis currents based on the torque command value. (5) in, and These are the reference values ​​for the d-axis and q-axis currents, respectively. For rotor self-inductance; The mutual inductance between the stator and rotor windings; This represents the number of pole pairs of the motor. This is the rotor flux command value; This determines that irregular wheel wear will introduce harmonics into the q-axis current, and the frequency is consistent with the excitation frequency of irregular wear. Step S233: Calculate the feedforward voltage based on the d-axis and q-axis currents. (6) in, The feedforward voltage is in the M coordinate system. The feedforward voltage is in the T-coordinate system; For stator resistance, Rotor resistance; For the self-sensing of the stator; Step S234: Substitute equation (4) into equation (6) and convert the feedforward voltage to a three-phase coordinate system. Then, the A-phase voltage of the motor stator can be expressed as: (7) in (8) (9) in, The fundamental frequency (angular frequency) of the motor stator current. Let be the rotation angle of the MT rotating coordinate system relative to the dq stationary coordinate system; This refers to the fundamental phase of phase A voltage; The phase angle of the rotor speed fluctuation; This represents the average rotor speed. The stator voltage contains harmonic components related to irregular wear of the wheels; Step S235: The vibration and impact caused by irregular wear will manifest as harmonic current in the stator current of the motor. Based on this, the frequency correspondence between the wheel irregular wear excitation and the stator harmonic current is determined as follows: (10) in, The frequency of the harmonic current; This is the motor's base frequency; The excitation frequency is the frequency of irregular wear of the wheel.

[0010] Furthermore, in step S300, a comb filter based on variable mode decomposition (VMD) is used to identify the characteristic frequency components of irregular wheel wear from the stator current in step S230.

[0011] Further, in step S300, a comb filter based on variable mode decomposition is used to identify the characteristic frequency components of irregular wheel wear from the stator current in step S230, specifically including: Step S310, decompose the stator current signal; the stator current signal extracted in step 230 The input is fed to the variable mode decomposition module, where it is decomposed into several modal components with finite bandwidths. The decomposition process minimizes the bandwidth of each mode and constrains their superposition to approximately equal the original signal. Stator current... It can be decomposed into (11) The objective functional form of VMD is: (12) in, The kth modal component of the stator current after VDM decomposition; The center frequency of the k-th mode; For Lagrange multipliers; As a penalty factor; The imaginary unit; The original stator current signal; K is the total number of modes; Step S320, reconstruct the spectrum; superimpose the spectra of the modal components decomposed into several finite bandwidths to obtain the coincident spectrum of the stator current, which can be expressed as: (13) in, The stator current spectrum; Indicates Fourier transform; Step S330, Stator target frequency set; Based on the frequency correspondence between the irregular wear excitation of the wheel and the stator harmonic current in step 230, i.e., equation (10), the target frequency set to be extracted is defined as follows: (14) in, Represents the target frequency set. This represents the frequency of irregular wear excitation, where p is the upper limit of the retained harmonic order; Step S340: Construct a combing frequency mask; using each frequency in the target frequency set as the center, construct a series of narrow passbands of equal width, with the passband width set to... Forming a makeup frequency mask , in, This is the frequency response function of the comb filter; This refers to the k-th discrete frequency point; For the target frequency; Where is the bandwidth of the narrowband channel; P is the number of target frequencies; Step S350, Spectrum filtering and signal extraction: The constructed comb mask is applied to the coincident spectrum signal of the stator current to achieve target frequency extraction.

[0012] (15) The time-domain signal i is obtained by performing an inverse Fourier transform on the filtered spectrum. h (t), the signal significantly retains the characteristic frequency components caused by polygonal wear; (16) in, This indicates the inverse Fourier transform.

[0013] Further, in step S300, the stator current signal extracted by the comb filter is combined with the fluctuation characteristics of the rotor speed to determine the target frequency to be extracted according to equation (10); accordingly, the harmonic components generated by the irregular wear excitation of the wheel are separated from the stator current.

[0014] Further, in step S300, the locomotive running speed is obtained, and the type of irregular wheel wear is determined by combining equation (3) and equation (10).

[0015] Furthermore, the irregular wear depth is determined based on the magnitude of the extracted harmonic current.

[0016] The technical solution provided in this application can achieve the following beneficial effects: This application analyzes the impact of irregular wheel wear on electrical parameters in an electric drive system based on an electromechanical coupling model, establishes the frequency relationship between irregular wear excitation and electrical parameters (stator harmonic current), and achieves accurate capture of wheel wear-related harmonics in the stator current by constructing a comb filter based on variable mode decomposition. This enables the detection of irregular wheel wear without the need for additional sensors, is low in cost, and is not easily affected by external environmental interference, thus having good engineering applicability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the traction converter drive system in this application; Figure 2 This is a schematic diagram of the train-track coupled dynamics model of this application; Figure 3 This is a schematic diagram of the electromechanical coupling model of the train traction drive system in this application; Figure 4 This is a time-domain diagram of the vertical acceleration of the wheelset in Embodiment 1 of this application. Figure 5 This is the vertical acceleration diagram (frequency domain) of the wheelset in Embodiment 1 of this application. Figure 6 This is a waveform diagram (time domain) of the wheel-rail normal force in Embodiment 1 of this application. Figure 7 This is a waveform diagram (frequency domain) of the wheel-rail normal force in Embodiment 1 of this application. Figure 8 This is the rotor speed diagram (time domain) in Embodiment 1 of this application; Figure 9 This is the rotor speed diagram (frequency domain) in Embodiment 1 of this application. Figure 10 This is the q-axis current diagram (time domain) in Embodiment 1 of this application; Figure 11 This is the q-axis current diagram (frequency domain) in Embodiment 1 of this application; Figure 12 This is the stator current diagram (time domain) of the motor in Embodiment 1 of this application; Figure 13 This is the stator current diagram (frequency domain) of the motor in Embodiment 1 of this application. Figure 14This is a polygonal wear-related frequency diagram of the stator current spectrum extracted in Embodiment 1 of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] In the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0021] The train traction drive system is essentially a complex closed-loop electromechanical coupling system. On the one hand, during actual train operation, the traction control system needs to collect and monitor electrical parameters in real time to ensure stable system operation. On the other hand, in the process of developing this application, the applicant discovered that the mechanical excitation caused by irregular wear such as polygonal wear of the wheels propagates step by step along the wheelset, gear transmission system, and rotor to the electrical side, ultimately causing fluctuations in electrical parameters (such as stator current). This propagation process provides a physical basis for wheel state sensing based on electrical signals. Therefore, if the wheel wear state can be sensed using existing electrical signals, no additional sensors are needed, which has good engineering feasibility and economy.

[0022] To address this, this application provides a method for detecting irregular wheel wear based on stator current analysis. Based on an electromechanical coupling model, it analyzes the impact of irregular wheel wear on electrical parameters in the electric drive system, establishing the frequency relationship between irregular wear excitation and electrical parameters (stator harmonic current). Furthermore, by constructing a comb filter based on variable mode decomposition, it achieves accurate capture of wheel wear-related harmonics in the stator current, thereby enabling the detection of irregular wheel wear. This method requires no additional sensor installation, is low-cost, and is not easily affected by external environmental interference, exhibiting good engineering applicability. Specific embodiments are described below.

[0023] Example 1 This embodiment uses the CRH3 high-speed train as the research object, with a traction power of 9600kW and a bogie axle arrangement of Bo-Bo. In this embodiment, polygonal wheel wear is imported into the train-track coupled dynamics model to illustrate the implementation process of the proposed method for monitoring irregular wheel wear.

[0024] The specific implementation process of this embodiment is as follows: Step 1: Taking into account the key parameters of the electrical and mechanical components of the high-speed train traction drive system, establish separate models for the traction converter drive system and the train-track coupled dynamics model. Then, integrate these two models and construct a closed-loop feedback mechanism based on the input / output relationship between the electrical and mechanical sides to form a complete electromechanical coupling model of the traction drive system. Specifically: (1) A traction converter drive system model was built in MATLAB / Simulink, including a rectifier, intermediate DC link, inverter, and traction motor (asynchronous motor). A two-level single-phase pulse rectifier was constructed, which adopted transient current control and pulse width modulation (PWM); a two-level three-phase inverter was constructed, which adopted field-oriented vector control and space vector pulse width modulation (SVPWM). The schematic diagram of the traction converter drive system model in this embodiment is shown below. Figure 1 As shown.

[0025] (2) Construct a high-speed train-track coupled dynamics model in the multibody dynamics software SIMPACK, such as Figure 2 As shown. This model includes: a train subsystem, a track subsystem, and a wheel-rail coupling subsystem. Specifically: (a) A vehicle dynamics model was constructed, comprising a car body, two bogies, four wheelsets, four gearboxes, and four motors. The wheelsets were modeled as flexible bodies, and their modeling and modal analysis were performed in Ansys / APDL. Mode shapes of orders 7 to 25, covering a frequency range up to 1000 Hz, were selected and imported into the vehicle dynamics model. The motor-gear transmission model included a stator, rotor, drive gear, and driven gear.

[0026] (b) The track is simulated as a dual-mass (sleeper-ballast)-spring-damped model, and the rail is simulated as an infinitely long Timoshenko beam supported by continuous elastic discrete points.

[0027] (c) The wheel-rail coupling model is implemented through normal contact modeling and tangential contact modeling.

[0028] Normal contact modeling is implemented based on Hertz nonlinear elastic contact theory, and can be expressed as follows: (17) in For the wheel-rail normal force; The wheel-rail contact constant; It is the elastic compression between the wheel and the rail, determined by the vertical displacement of the wheel and the rail at the wheel-rail contact point.

[0029] Tangential contact modeling is achieved using simplified Kalker theory, enabling the solution of tangential stresses generated by wheel-rail interaction, which can be expressed as follows: (18) in and These are the tangential stresses in the x (longitudinal) and y (lateral) directions, respectively. , and These are longitudinal, transverse, and spin creep rates, respectively. , and These are the longitudinal, transverse, and spin compliance coefficients, respectively, where a0 is the longitudinal coordinate of the particle with transverse coordinate y0 at the leading edge of the contact patch.

[0030] (3) Using SIMAT, the interface between MATLAB and SIMPACK, the traction converter drive system model (electrical subsystem) established in step 1 and the train-track coupled dynamics model (mechanical subsystem) established in step 2 are integrated into the same simulation environment, and the electrical subsystem is used to realize real-time control of the mechanical subsystem. Specifically: the driving torque output by the electrical subsystem is transmitted to the mechanical subsystem through SIMAT and applied to the motor rotor; at the same time, the mechanical angular velocity of the motor rotor is fed back to the motor control module of the electrical subsystem through SIMAT. Through the above bidirectional transmission, closed-loop feedback and real-time interaction between the electrical subsystem and the mechanical subsystem are realized. A schematic diagram of the electromechanical coupling model established in this step is shown below. Figure 3 As shown.

[0031] Step 2: Based on the electromechanical coupling model, analyze the time-frequency characteristics of the electrical and mechanical parameters in the traction drive system under the excitation of irregular wheel wear, and establish the mathematical relationship between irregular wheel wear and stator harmonic current. Specifically: (1) In the train-track coupled dynamics model, wheel polygonal wear is introduced in the form of radius deviation, with a wear depth of 0.05 mm and an order of 18. In this simulation, the locomotive speed is 261 km / h and the wheel radius is 0.43 m. The excitation frequency corresponding to wheel wear can be calculated as follows: (19) in, The train's operating speed; The radius of the wheel; Let be the order of polygonal wear on the wheel. Solving for the excitation frequency of the polygonal wear pattern yields the result. The frequency is 481.7 Hz.

[0032] (2) Running the electromechanical coupling model, the train-track coupled dynamics model outputs the wheelset vibration acceleration. Orbital normal force ( ), rotor speed ( ), and perform spectrum analysis on the above mechanical parameters, as shown below. Figures 4-9As shown. Then, the mechanical parameter fluctuation frequency and the polygonal wear excitation frequency are compared. By performing a corresponding matching, it can be observed that the wheel-rail vibration caused by the polygonal wear of the wheel is transmitted to the traction converter drive system through the gear transmission system, and finally transmitted in the form of rotor speed fluctuations. Furthermore, the frequency of these rotor speed fluctuations is consistent with... Consistent.

[0033] (3) Extract key electrical parameters such as d-axis and q-axis currents and stator currents from the motor control module; perform spectrum analysis on the above electrical parameters, and establish a mapping relationship between wheel wear excitation and stator current in conjunction with rotor speed fluctuations, specifically including: (a) In motor control, the torque command value calculated based on the speed sub-fluctuation can be expressed as: (20) Among them, express The excitation angular frequency of the polygonal wheel. and These are the proportional and integral coefficients in the speed regulation module. This is the torque command value; ω r and These are the actual and set values ​​of the rotor speed, respectively. and This refers to the amplitude and phase of the torque command value fluctuation.

[0034] (b) Calculate the d-axis and q-axis currents based on the torque command values: (twenty one) in, and These are the reference values ​​for the d-axis and q-axis currents, respectively. For rotor self-inductance; The mutual inductance between the stator and rotor windings; This represents the number of pole pairs of the motor. This is the rotor flux command value; This determines that irregular wheel wear introduces harmonics into the q-axis current, with the frequency matching the excitation frequency of the irregular wear. The calculated q-axis current and its spectrum are as follows. Figure 10 and Figure 11 As shown.

[0035] (c) The feedforward voltage is calculated based on the d-axis and q-axis currents. (twenty two) in, and The feedforward voltage is in the MT coordinate system; and For stator and rotor resistance; and For stator and rotor self-inductance; The mutual inductance between the stator and rotor windings; This represents the number of pole pairs of the motor.

[0036] (d) Substituting equation (20) into equation (22), and converting the feedforward voltage to a three-phase coordinate system, the stator A-phase voltage of the motor is calculated as follows: (twenty three) in (twenty four) (25) The fundamental frequency (angular frequency) of the motor stator current. Let be the rotation angle of the MT rotating coordinate system relative to the dq stationary coordinate system; This refers to the fundamental phase of phase A voltage; The phase angle of the rotor speed fluctuation; This represents the average rotor speed. Therefore, it can be concluded that the stator voltage contains harmonic components related to polygonal wear, i.e. , wait.

[0037] (e) This invention focuses on the structure of voltage source inverters. Vibration shocks caused by irregular wear will manifest as harmonic currents in the motor stator current. Based on this, the frequency correspondence between the wheel irregular wear excitation and the stator harmonic current can be determined as follows: (26) in, The frequency of the harmonic current; This is the motor's base frequency; Let n be the excitation frequency of irregular wheel wear, and n be a positive integer. The time-frequency characteristics of the A-phase stator current signal extracted from the electromechanical coupling model are as follows: Figure 12 and Figure 13 As shown, it can be observed that the polygonal wear excitation frequency couples with the motor's fundamental frequency to generate harmonic current.

[0038] Step 4: Establish a comb filter based on Variational Mode Decomposition (VMD) to identify the characteristic frequency components of irregular wheel wear from the stator current in Step 3. Specifically, this includes: (a) Decompose the stator current signal. The stator current signal extracted in step 3... The input is fed to the variable mode decomposition module, where it is decomposed into several mode components with finite bandwidths. The decomposition process minimizes the bandwidth of each mode and constrains their superposition to approximately equal the original signal. Stator current Don't break it down into (27) The objective functional form of VMD is: (28) in, The kth modal component of the stator current after VDM decomposition; The center frequency of the k-th mode; For Lagrange multipliers; As a penalty factor; The imaginary unit; The original stator current signal; K is the total number of modes; (b) Reconstructing the spectrum. The coincident spectrum of the stator current is obtained by superimposing the spectra of the above modal components, which can be expressed as: (29) in, The stator current spectrum, This represents the Fourier transform.

[0039] (c) Stator target frequency set. Based on the frequency correspondence between the irregular wheel wear excitation and the stator harmonic current in step 3, i.e., equation (10), the target frequency set to be extracted is defined as follows: (30) in, Represents the target frequency set; This indicates the frequency of the irregular wear excitation; p is the upper limit of the retained harmonic order.

[0040] (d) Constructing a combing frequency mask. Using each frequency in the target frequency set as the center, construct a series of narrow passbands of equal width, with the passband width set to... To form a comb-shaped frequency mask .

[0041] in, This is the frequency response function of the comb filter; This refers to the k-th discrete frequency point; For the target frequency; is the bandwidth of the narrowband channel; P is the number of target frequencies.

[0042] (e) Spectral filtering and signal extraction. The constructed comb mask is applied to the coincidence spectrum signal of the stator current to achieve target frequency extraction.

[0043] (31) Performing an inverse Fourier transform on the filtered spectrum yields the time-domain signal i containing the polygonal wear excitation frequency.h (t), the signal significantly retains the characteristic frequency components caused by polygonal wear; (32) in, This indicates the inverse Fourier transform.

[0044] Step 5: Apply the comb filter constructed in Step 4 to the stator current signal extracted in Step 3, and combine it with the fluctuation characteristics of the rotor speed to... and Substituting into equation (30), the target frequency to be extracted is determined. Based on this, the harmonic components generated by the irregular wear excitation of the wheel are separated from the stator current, such as... Figure 14 As shown. Subsequently, based on the locomotive's operating speed of 261 km / h, and combining equations (19) and (30), it can be determined that the wheels exhibit polygonal wear.

[0045] It should be noted that, in this document, 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. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting irregular wear of a train wheel based on stator current analysis, for detecting irregular wear of a train wheel, characterized by, The method comprises the following steps: Step S100, a traction converter drive system model of a train, a train-track coupling dynamics model are established, and the traction converter drive system model and the train-track coupling dynamics model are integrated, a closed-loop feedback mechanism is constructed according to the input / output relationship of the electrical side and the mechanical side, and an electromechanical coupling model of the traction transmission system is formed; Step S200, based on the electromechanical coupling model, time-frequency characteristics of electrical parameters and mechanical parameters in the traction transmission system under irregular wear excitation of a wheel are obtained, the electrical parameters include stator current, and the mechanical parameters include wheelset vibration acceleration, wheel-rail normal force and rotor speed; a mathematical relationship between irregular wear of the wheel and stator harmonic current is established, wherein, is the harmonic current frequency; is the motor fundamental frequency; is the excitation frequency of the irregular wear of the wheel, n is a positive integer; Step S300, a harmonic component generated by irregular wear excitation is separated from the stator current through a comb filter, and detection of irregular wear of the wheel is realized.

2. The irregular wheel wear detection method based on stator current analysis according to claim 1, characterized in that, The traction converter drive system model comprises a rectifier, an intermediate direct current link, an inverter and a traction motor; and the train-track coupling dynamics model comprises a train subsystem, a track subsystem and a wheel-rail coupling subsystem.

3. The irregular wheel wear detection method based on stator current analysis according to claim 2, characterized in that, A traction converter drive system model is built in MATLAB / Simulink, and a track train-track coupling dynamics system model is constructed in a commercial multi-body dynamics software SIMPACK; the train-track coupling dynamics model comprises a vehicle dynamics model of a car body, two bogies, four wheelsets, four gearboxes and four motors; The wheelset is modeled as a flexible body, modeling and modal analysis of which are realized in Ansys / APDL; modal vibration modes of 7-25 orders and in a frequency range covering 1000 Hz are selected and imported into the vehicle dynamics model; the motor-gear transmission model comprises a stator, a rotor, a driving gear and a driven gear; The track is simulated as a double-mass (sleeper-track bed) spring damping model; The rail is simulated as an infinite Timoshenko beam supported by discrete points in a continuous elastic manner; The wheel-rail coupling subsystem is realized through normal contact modeling and tangential contact modeling; the normal contact modeling is realized based on Hertz nonlinear elastic contact theory and is expressed as (1) wherein is the wheel-rail normal force; is the wheel-rail contact constant; is the elastic compression between the wheel and the rail, determined by the vertical displacement of the wheel and the rail at the wheel-rail contact point; The tangential contact modeling is realized by simplified Kalker theory, realizes solving of tangential stress generated by wheel-rail interaction, and is expressed as (2) where and are the tangential stresses in the x (longitudinal) and y (transverse) directions, respectively; , and are the longitudinal, transverse and spin creep rates, respectively; , and are the longitudinal, transverse and spin compliance coefficients, respectively, and a0is the longitudinal coordinate of the point on the leading edge of the contact patch corresponding to a transverse coordinate of y0. The established traction converter drive system model and the train-track coupling dynamics model are integrated into the same simulation environment by using an interface SIMAT between MATLAB and SIMPACK, and the traction converter drive system model realizes real-time control of the train-track coupling dynamics model.

4. The irregular wheel wear detection method based on stator current analysis according to claim 3, characterized in that, The driving torque output by the traction converter drive system model is transmitted to the train-track coupling dynamics model through SIMAT and is applied to the motor rotor; meanwhile, the mechanical angular velocity of the motor rotor is fed back to the motor control module of the electric traction converter drive system model through SIMAT, and through the above-mentioned bidirectional transmission, closed-loop feedback and real-time interaction between the traction converter drive system model and the train-track coupling dynamics model are realized.

5. The irregular wheel wear detection method based on stator current analysis according to any one of claims 1-4, characterized in that, In step S200, the time-frequency characteristics of the electrical and mechanical parameters in the traction drive system under the wheel irregular wear excitation are obtained by including the following steps, and the mathematical relationship between the wheel irregular wear and the stator harmonic current is established: Step S210, the wheel irregular wear is introduced in the form of radius deviation in the train-track coupling dynamics model, the irregular wear includes wheel flat and wheel polygonal wear, and the excitation frequency corresponding to the wheel wear is solved, which can be calculated as: （3） wherein, is the train running speed; is the wheel radius; is the wheel polygonal wear order; Step S220, run the electromechanical coupling model, the train-track coupling dynamics model outputs mechanical parameters including wheelset vibration acceleration ( ), wheel-rail normal force ( ) and rotor speed ( ); perform frequency spectrum analysis on the output mechanical parameters, and correspondingly match with in formula (3) to identify the transmission path and rule of wheel wear excitation in the mechanical transmission system; Step S230, the key electrical parameters including d-axis current, q-axis current and stator current are extracted from the motor control module; the extracted key electrical parameters are subjected to frequency spectrum analysis, and the mapping relationship between the wheel wear excitation and the stator current is established in combination with the rotor speed fluctuation, which specifically includes: Step S231, in the motor control module, the torque command value calculated according to the rotor speed fluctuation can be expressed as (4) wherein, denotes the excitation frequency of the polygon of the wheel, and are proportional and integral coefficients in the speed regulation module, is a torque command value; ω r and are the actual and set values of the rotor speed, respectively; and are the amplitude and phase of the torque command value fluctuation. Step S232, according to the torque command value, the d-axis and q-axis currents are calculated: (5) wherein, and are d-axis and q-axis current reference values, respectively; is a rotor self-inductance; is a mutual inductance of stator and rotor windings; is a number of motor pole pairs; is a rotor flux command value; Thus it is determined that the wheel irregular wear will introduce harmonics in the q-axis current, and the frequency is consistent with the irregular wear excitation frequency; Step S233, the feedforward voltage is calculated according to the d-axis and q-axis currents (6) wherein, is the feed-forward voltage in the M coordinate system, is the feed-forward voltage in the T coordinate system; is the stator resistance, is the rotor resistance; is the stator self-inductance; Step S234, substituting formula (4) into formula (6), and converting the feedforward voltage to the three-phase coordinate system, then the motor stator A-phase voltage can be expressed as (7) Wherein (8) (9) wherein, is the fundamental frequency of the stator current of the electric machine, is the rotation angle of the MT rotating coordinate system to the dq stationary coordinate system; is the fundamental phase of the A-phase voltage; is the phase angle of the rotor speed fluctuation; is the average value of the rotor speed; The stator voltage contains harmonic components related to the wheel irregular wear; Step S235, the vibration impact caused by the irregular wear will be reflected in the form of harmonic current in the motor stator current, based on this, the frequency correspondence relationship between the wheel irregular wear excitation and the stator harmonic current is determined as: (10) wherein, is the harmonic current frequency; is the motor fundamental frequency; is the excitation frequency of the irregular wear of the wheel.

6. The irregular wheel wear detection method based on stator current analysis according to claim 5, characterized in that, In step S300, the characteristic frequency components of the wheel irregular wear are identified from the stator current in step S230 by using a comb filter based on variable mode decomposition.

7. The irregular wheel wear detection method based on stator current analysis according to claim 6, characterized in that, In step S300, the characteristic frequency components of the wheel irregular wear are identified from the stator current in step S230 by using a comb filter based on variable mode decomposition (VMD), which specifically includes: Step S310, decompose the stator current signal; the stator current signal extracted in step 230 is decomposed into a plurality of modal components with limited bandwidths input into a variable mode decomposition module, and decomposed into a plurality of modal components with limited bandwidths; the decomposition process minimizes the bandwidth of each mode and constrains the superposition of the modes to be approximately equal to the original signal; the stator current decomposable into (11) The objective functional form of VMD is (12) wherein, is the kth modal component of the stator current after decomposition by the VDM; is the center frequency of the kth mode; is the Lagrange multiplier; is the penalty factor; is the imaginary unit; is the original stator current signal; K is the total number of modes; Step S320, reconstruct the frequency spectrum; the frequency spectrum of the stator current is obtained by superimposing the frequency spectrum of the modal components decomposed into several finite bandwidths, which can be expressed as: (13) wherein is the stator current spectrum; denotes the Fourier transform; Step S330, stator target frequency set; according to the frequency correspondence relationship between the wheel irregular wear excitation and the stator harmonic current in step 230, i.e. formula (10), the target frequency set to be extracted is defined as: (14) wherein, represents a target frequency set; represents an irregular wear excitation frequency; p is the upper limit of the retained harmonic order; Step S340, construct a comb frequency mask; a series of narrow band-pass bands with equal width are constructed with each frequency in the target frequency set as the center, and the width of the band-pass band is set as , form a comb frequency mask wherein, is a frequency response function of a comb filter; is the kth discrete frequency point; is a target frequency; is a bandwidth of a narrow band channel; P is a number of target frequencies; Step S350, frequency spectrum filtering and signal extraction; the constructed comb mask is applied to the composite frequency spectrum signal of the stator current to realize target frequency extraction; (15) Inverse Fourier transforming the filtered spectrum to obtain a time domain signal i h (t), which signal significantly retains the characteristic frequency components caused by polygonal wear; (16) wherein denotes an inverse Fourier transform.

8. The irregular wheel wear detection method based on stator current analysis according to claim 7, characterized in that, In step S300, the stator current signal extracted by the comb filter is combined with the fluctuation characteristics of the rotor speed to determine the target frequency to be extracted according to formula (10); accordingly, the harmonic components generated by the wheel irregular wear excitation are separated from the stator current.

9. The irregular wheel wear detection method based on stator current analysis according to claim 8, characterized in that, In step S300, the locomotive running speed is obtained, and the type of wheel irregular wear is determined in combination with formula (3) and formula (10).

10. The irregular wheel wear detection method based on stator current analysis according to claim 9, characterized in that, Based on the amplitude of the extracted harmonic current, the depth of irregular wear is determined.

Images