Anti-skid control method for high-speed train

Abstract

The invention discloses an anti-skid control method for a high-speed train at a higher speed, which comprises the following steps of: firstly, acquiring basic information such as the speed and the axle load of the high-speed train in real time through a sensor, establishing a real-time analysis model by virtue of data, then calculating a real-time adhesion coefficient, and further judging the rail surface state of wheel-rail contact of the high-speed train; the optimal creep rate under the current rail surface condition is calculated based on the information, the traction or braking torque is adjusted through a control strategy by comparing the optimal creep rate with the actual creep rate in real time, anti-skid control adjustment is conducted, and the adhesion utilization rate and operation safety are improved. According to the method, for a high-speed train at a higher speed, the torque is changed through adhesion control, so that anti-skid control is carried out, the adhesion utilization rate and the operation safety are improved, and wheel skid and abnormal abrasion can be effectively restrained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rail transit, in particular to a method for anti-skid control of a high-speed train. BACKGROUND

[0002] At present, the highest operating speed of China's railway high-speed train set is 350 km / h. In the future, with the deepening of China's research, higher speed train sets will be introduced, which will greatly enhance urban connectivity, compress time and space distance, improve travel efficiency, increase travel comfort, and become a beautiful card on the road of revitalization.

[0003] Higher speed trains face various complex environmental factors during operation, such as slippery tracks, sharp acceleration and deceleration, and sudden climate changes, and the effective adhesion between the wheel and the rail will be significantly weakened, so the role of anti-skid control is particularly important. This control mainly monitors the friction between the train wheel and the track, and judges in real time whether the train is in a sliding state to control it. When the friction between the wheel and the track is detected to be reduced to a certain threshold, the anti-skid control will immediately intervene to automatically adjust the train's traction and braking system to prevent wheel skidding and avoid traction or braking wheel rail abrasion.

[0004] Optimal adhesion control is an advanced control strategy for improving the traction performance of trains under different operating conditions, especially in high-speed trains. Its core goal is to maximize the traction performance and braking safety of the train by reasonably controlling the adhesion between the wheel and the track, while avoiding wheel skidding or sliding. When implementing optimal adhesion control, the dynamic characteristics and operating environment of the train are considered, and the optimal control amount is calculated in real time to maintain the best adhesion during acceleration and braking. This method not only improves the stability and safety of the train in complex environments, but also improves energy efficiency and reduces energy consumption.

[0005] PID control and sliding mode control are both excellent control methods. PID control has lower computational complexity and is stable in linear systems, with slower dynamic response and sensitivity to parameter changes and disturbances, commonly used in traditional industrial scenarios; sliding mode control has higher computational complexity and is globally stable under the design of a reasonable sliding surface, with fast convergence, suitable for high dynamic systems, good robustness, and currently used in advanced field control. The advantage of sliding mode control will be greater than that of PID control in anti-skid control of high-speed trains at higher speeds. SUMMARY

[0006] In order to solve the problems in the prior art, the purpose of the present application is to provide a high-speed train anti-skid control method, which is aimed at high-speed trains at higher speeds, changes the torque through adhesion control, thereby performing anti-skid control, improves adhesion utilization rate and running safety, and can effectively inhibit wheel skidding and abnormal wear.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a high-speed train anti-skid control method, comprising the following steps:

[0008] Step 1: obtaining basic information that can be detected during the running of a high-speed train, and establishing a real-time analysis model according to the basic information;

[0009] Step 2: calculating a real-time adhesion coefficient according to the parameters of the high-speed train and the track and the analysis model;

[0010] Step 3: judging the track surface state of the wheel-rail contact of the high-speed train according to the basic information, the adhesion coefficient and the wheel-rail longitudinal creep rate;

[0011] Step 4: calculating an optimal creep rate corresponding to the peak point of the adhesion coefficient, i.e. an optimal creep threshold value;

[0012] Step 5: comparing the optimal creep rate with the actual creep rate, and adjusting the traction or braking torque through a control strategy to perform anti-skid control adjustment.

[0013] As a further improvement of the present application, in step 1, the establishment method of the analysis model is as follows:

[0014] Based on the vehicle-track coupling dynamics theory, a high-speed train vehicle-track coupling dynamics model considering wheelset flexibility is established; including a vehicle system dynamics model, a track system dynamics model and a wheel-rail interaction model.

[0015] As a further improvement of the present application, the step 2 is as follows:

[0016] Firstly, a wheel-rail contact model is determined, and in the wheel-rail interaction model, the normal stress distribution in the contact patch is as follows:

[0017]

[0018] wherein ξ and η are the lateral coordinate and the longitudinal coordinate of the wheel when advancing, p z is the maximum wheel-rail contact pressure, which is calculated by the following formula:

[0019]

[0020] wherein a is a virtual penetration distance, E and u are the Young's modulus and Poisson's ratio of the wheel-rail material, respectively, x n is the contact patch front, yn and y m are the left and right boundaries of the contact patch, respectively;

[0021] The wheel-rail normal force is solved by integrating the normal contact stress distribution within the contact patch:

[0022]

[0023] The adhesion zone and the sliding zone within the contact patch are divided, and the tangential stress distribution is solved. The adhesion zone and the sliding zone within the contact patch are divided according to the following formula:

[0024]

[0025] In the adhesion zone, the wheel-rail tangential stress is represented as:

[0026]

[0027] In the sliding zone, k and λ are related to the creep rate and the spin. The wheel-rail tangential stress is represented as:

[0028]

[0029] where q xf and q yf are the wheel-rail tangential contact stress within the sliding zone, p0 is the maximum pressure value, and μ is the friction coefficient.

[0030] The variable friction coefficient model is used to modify the friction coefficient, which is expressed as:

[0031]

[0032] where μ0 is the maximum friction coefficient; v g is the relative sliding speed between the wheel and the rail; A k is the ratio of the friction coefficient corresponding to infinite creep to the maximum friction coefficient; B k is the friction force exponential decay coefficient.

[0033] The wheel-rail longitudinal and lateral creep forces and the spin moment are solved by integration:

[0034]

[0035] When the wheel slips, the formula for calculating the adhesion coefficient is as follows:

[0036]

[0037] where ξ is the adhesion coefficient; F Q is the traction or braking force; F d is the wheel-rail adhesion force; and Q is the wheel-rail normal force.

[0038] The wheel-rail adhesion coefficient is observed by an observer:

[0039]

[0040] where n is the number of wheelsets, is the observed wheel-rail adhesion force, and its expression is:

[0041]

[0042] The calculation formula of the operator is solved by the following equation:

[0043]

[0044] where is the equivalent traction or braking force at the rolling circle radius of the wheel; λ is the low-pass filter cutoff frequency of the observer; J c is the wheelset moment of inertia; ω n is the wheelset angular velocity; R c is the wheel radius.

[0045] As a further improvement of the present application, in step 3, the wheel-rail longitudinal creep rate is calculated by the wheelset forward speed and the wheelset rotational speed:

[0046]

[0047] where v n is the wheelset forward speed.

[0048] As a further improvement of the present application, step 5 is specifically as follows:

[0049] After the optimal creep threshold is calculated, the traction or braking torque needs to be adjusted in time to avoid wheel slip and make the wheel-rail longitudinal creep rate track the optimal creep threshold in real time. The control action on the traction or braking torque is only triggered when the wheel-rail longitudinal creep rate exceeds the optimal threshold. The sliding mode control algorithm formula is as follows:

[0050] s = |s n (t) | - |s o |

[0051] where s is the sliding surface, representing the error between the current creep rate and the optimal creep rate, s n (t) represents the current creep rate, and s o represents the optimal front creep rate.

[0052] The optimal adhesion traction or braking torque sliding mode control law is:

[0053]

[0054] Where, I wy is the wheelset rotational inertia, M v is the total mass of the vehicle body, sgn(s) uses a sign function to suppress high-frequency jitter, and q and k satisfy the following conditions:

[0055]

[0056] The present invention first collects basic parameters of the high-speed train and operating rail parameters. During operation, it then acquires measurable basic information such as vehicle speed and axle weight. Based on this information, a high-speed model is established. The adhesion coefficient is then calculated based on the train and track parameters and the model. Based on this existing and calculated data, the contact state is determined and the creep rate corresponding to the peak point of the adhesion coefficient, i.e., the optimal creep threshold, is calculated. After providing real-time feedback on the optimal creep threshold for the current rail adhesion characteristics, the control system implements a control strategy based on this dynamic threshold parameter, dynamically adjusting the traction / braking torque output to prevent wheel slip and keep the longitudinal creep rate near the optimal threshold in real time. This maximizes traction / braking adhesion, improves adhesion coefficient utilization, and reduces energy consumption. This method can calculate the optimal creep threshold under the current track surface adhesion characteristics in real time when a higher-speed train is running in a complex environment, and control traction / braking based on the optimal threshold, providing an anti-skid control method at higher speeds. Its application scope includes: 1. This method integrates the basic parameters of higher-speed trains with real-time operation data to construct an adhesion coefficient calculation model based on wheel-rail contact spot stress analysis; 2. Anti-skid control is adjusted in a timely manner based on the optimal creep threshold to match the adhesion characteristics under different climate and track surface conditions; 3. Based on the optimal creep threshold identified in real time, an anti-skid control strategy is used to dynamically adjust the traction / braking torque to keep the longitudinal creep rate near the target threshold.

[0057] The beneficial effects of the present invention are:

[0058] 1. Based on advanced vehicle-track coupling dynamics theory, this paper establishes a high-speed train vehicle-track coupling dynamics model that takes wheelset flexibility into account. This model includes a vehicle system dynamics model, a track system dynamics model, and a wheel-rail interaction model, enabling more accurate simulation of wheel-rail interaction at higher speeds.

[0059] 2. At higher speeds, the present invention explores the changes in the adhesion coefficient and the wheel-rail longitudinal creep rate, which can better judge the rail surface state and further perform corresponding anti-slip control, increasing the accuracy of the model and improving calculation efficiency.

[0060] 3. At higher speeds, the present invention compares two different anti-skid control strategies. The results show that within the contact patch, sliding mode control produces lower normal contact stress than PID control. In terms of dynamic performance, sliding mode control produces smaller oscillation amplitudes of wheel-rail vertical force and wheel-axle lateral force than PID control. This suggests an anti-skid control method more suitable for higher speeds, effectively suppressing wheel slippage and improving adhesion utilization and driving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a flow chart of an embodiment of the present invention;

[0062] Figure 2 Schematic diagram of a high-speed train vehicle-track coupled dynamics model at higher speeds according to an embodiment of the present invention;

[0063] Figure 3 Schematic diagram of the wheel-rail spatial contact geometric relationship in an embodiment of the present invention;

[0064] Figure 4 Schematic diagram of the adhesion characteristic surface under different wheel-rail contact and speed conditions in an embodiment of the present invention;

[0065] Figure 5 This is a wheel-rail adhesion characteristic curve diagram of a 400 km / h or higher high-speed train according to an embodiment of the present invention;

[0066] Figure 6 This is a schematic diagram of the anti-skid control principle of an embodiment of the present invention;

[0067] Figure 7 Schematic diagram of wheel-rail normal contact stress distribution at stress peak using different anti-skid control strategies;

[0068] Figure 8 Schematic diagram for comparing dynamic performance using different anti-skid control strategies. DETAILED DESCRIPTION

[0069] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0070] Example

[0071] like Figure 1 As shown, a skid control method for high-speed trains at higher speeds, the specific steps are as follows:

[0072] S1, obtain the basic parameters and real-time operation data of high-speed trains.

[0073] S2, based on the information in S1, constructs an analysis model at higher speed. The high-speed train vehicle-track coupling dynamics model at higher speed is as follows: Figure 2 shown.

[0074] S3, calculate the adhesion coefficient according to the information of S1 and the model of S2, in which the wheel-rail contact model is determined first, such as Figure 3 As shown in the figure, thus the normal stress distribution in the contact patch in the wheel-rail interaction model is as follows:

[0075]

[0076] where ξ and η are the lateral coordinate and longitudinal coordinate of the wheel when advancing, p z is the maximum contact pressure of the wheel-rail, which can be calculated by the following formula:

[0077]

[0078] where a is the virtual penetration distance, E and u are the Young's modulus and Poisson's ratio of the wheel-rail material, x n is the front edge of the contact patch, y n and y m are the left and right boundaries of the contact patch, respectively.

[0079] The wheel-rail normal force can be solved by integrating the normal contact stress distribution in the contact patch:

[0080]

[0081] The adhesion zone and the sliding zone in the contact patch are divided, and the tangential stress distribution is solved, and the range of the adhesion zone and the sliding zone in the contact patch is divided according to the following formula:

[0082]

[0083] The wheel-rail tangential stress in the adhesion zone can be expressed as:

[0084]

[0085] In the sliding zone, k and λ are related to the creep rate and spin. The wheel-rail tangential stress can be expressed as:

[0086]

[0087] where q xf and q yf are the wheel-rail tangential contact stresses in the sliding zone solved by the FASTSIM wheel-rail creep model, p0 is the maximum pressure value, and μ is the friction coefficient.

[0088] The vehicle performs traction or braking operation under low adhesion contact conditions, which affects the wheel-rail friction coefficient, so a variable friction coefficient model is used to modify the friction coefficient, and its expression is:

[0089]

[0090] where μ0is the maximum friction coefficient; v g is the wheel-rail relative sliding speed; A k is the ratio of the friction coefficient corresponding to the infinite creep to the maximum friction coefficient; B k is the friction force exponential decay coefficient.

[0091] The wheel-rail longitudinal, lateral creep forces and spin moment can be solved by integration:

[0092]

[0093] When the wheel slips, the calculation formula of the adhesion coefficient is as follows:

[0094]

[0095] where ξ is the adhesion coefficient; F Q is the traction or braking force; F d is the wheel-rail adhesion force; Q is the wheel-rail normal force.

[0096] In the model, the wheel-rail adhesion coefficient is observed by an observer:

[0097]

[0098] where n is the wheelset number, is the wheel-rail adhesion force observation value, and its expression is:

[0099]

[0100] Operator The calculation formula of the operator is solved by the following equation:

[0101]

[0102] where, is the equivalent traction or braking force at the rolling circle radius of the wheel; λ is the low-pass filter cutoff frequency of the observer; J c is the wheelset moment of inertia; ω n is the wheelset angular velocity; R c is the wheel radius.

[0103] S4, based on the basic information of S1, the calculated adhesion coefficient of S3, the wheel-rail longitudinal creep rate is calculated again, and the wheel-rail longitudinal creep rate can be calculated by the wheelset forward speed and the wheelset rotation speed:

[0104]

[0105] where v n is the wheelset forward speed.

[0106] According to the above information, the rail surface state of the current wheel-rail contact is determined, as shown in FIG. 3, which is a curve of adhesion characteristics under different wheel-rail contact and speed conditions. Figure 4

[0107] S5, according to the information of S1, S3 and S4, the optimal creep rate corresponding to the peak point of the adhesion coefficient is calculated, as shown in FIG. 4, which is a curve of wheel-rail adhesion characteristics of a high-speed train at 400 km / h. Figure 5

[0108] S6, by comparing the optimal creep rate calculated in S5 with the actual creep rate, the adhesion control strategy is used to timely adjust the traction / braking torque to avoid wheel slip and make the wheel-rail longitudinal creep rate track the optimal creep threshold in real time. The control action of the traction / braking torque is only triggered when the wheel-rail longitudinal creep rate exceeds the optimal threshold. The sliding mode control algorithm is as follows:

[0109] s = |s n (t) - |s o | (17)

[0110] In the formula, s is a sliding surface, which represents the error between the current creep rate and the optimal creep rate. It is also taken as a target function, aiming to gradually approach the optimal creep rate, so as to improve the adhesion utilization rate and suppress wheel slip. s n (t) represents the current creep rate, and s o represents the optimal creep rate.

[0111] The optimal adhesion traction / braking torque sliding mode control law is:

[0112]

[0113] In the formula, Iwy is the rotational inertia of the wheelset, M v is the total mass of the vehicle body, and sgn(s) is a sign function used to suppress high-frequency jitter. The Lyapunov stability criterion is used as a constraint condition, and q and k need to satisfy the following conditions:

[0114]

[0115] The control principle is shown in FIG. 5. PID control and sliding mode control are used for optimal adhesion control, respectively. The effects of the two control strategies are compared, as shown in FIGS. 6 and 7. In the contact patch, the normal contact stress of the sliding mode control is lower than that of the PID control. In terms of dynamic performance, the amplitude of the wheel-rail vertical force and the wheel axle lateral force oscillation of the sliding mode control is smaller than that of the PID control. The effect of the sliding mode control is obviously better than that of the PID control. Figure 6 Figure 7 8

[0116] ​​​​​S7, judging whether to continue adjusting the traction or braking torque according to whether the real-time creep rate reaches the optimal creep rate.

[0117] S8, stopping the control of the traction or braking torque and keeping the current state.

[0118] The adhesion coefficient is one of the main factors affecting the safe operation of the high-speed train. In the embodiment, the error between the creep rate of the high-speed train in operation and the optimal creep rate is taken as a target function, aiming to improve the adhesion utilization rate and the operation safety, and effectively inhibit the wheel slip and abnormal wear.

[0119] The above-described embodiments only express the specific implementation of the present application, which is described in a more specific and detailed manner, but cannot be understood as a limitation on the patent scope of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application.

Claims

1. A high-speed train anti-skid control method, characterized in that: The following steps are involved: Step 1: Obtain basic information that can be detected during the operation of the high-speed train, and establish a real-time analysis model based on the basic information; Step 2: Calculating a real-time adhesion coefficient based on the parameters of the high-speed train and the track and the analysis model; Step 3: Determine the rail surface state of the high-speed train wheel-rail contact based on the basic information, adhesion coefficient, and wheel-rail longitudinal creep rate; Step 4: Calculate the optimal creep rate corresponding to the peak point of the adhesion coefficient, that is, the optimal creep threshold; Step 5: Compare the optimal creep rate with the actual creep rate, adjust the traction or braking torque through the control strategy, and perform anti-slip control adjustment.

2. The anti-skid control method for high-speed trains according to claim 1, characterized in that: In step 1, the method for establishing the analysis model is as follows: Based on the vehicle-track coupling dynamics theory, a high-speed train vehicle-track coupling dynamics model considering wheelset flexibility is established; it includes a vehicle system dynamics model, a track system dynamics model and a wheel-rail interaction model.

3. The anti-skid control method for high-speed trains according to claim 2, characterized in that: The step 2 is specifically as follows: First, the wheel-rail contact model is determined. In the wheel-rail interaction model, the normal stress distribution within the contact patch is as follows: Among them, ξ and η are the horizontal and longitudinal coordinates of the wheel when it moves forward, respectively, and p z is the maximum wheel-rail contact pressure, which is calculated by the following formula: Where a is the virtual penetration distance, E and u are the Young's modulus and Poisson's ratio of the wheel and rail material, respectively, and x n is the contact patch front, y n and y m are the left and right boundaries of the contact patch, respectively; The wheel-rail normal force is solved by integrating the normal contact stress distribution within the contact patch: The adhesion zone and sliding zone within the contact patch are divided to solve the tangential stress distribution. The adhesion zone and sliding zone within the contact patch are divided according to the following formula: In the adhesion zone, the wheel-rail tangential stress is expressed as: In the sliding zone, k and λ are related to creep rate and spin. The wheel-rail tangential stress is expressed as: Where q xf and q yf is the wheel-rail tangential contact stress in the sliding zone, p0 is the maximum pressure value, and μ is the friction coefficient; The variable friction coefficient model is used to correct the friction coefficient, and its expression is: Where μ0 is the maximum friction coefficient; v g is the relative sliding speed of wheel and rail; A k B is the ratio of the friction coefficient corresponding to infinite creep to the maximum friction coefficient; k is the friction exponential attenuation coefficient; The wheel-rail longitudinal and transverse creep forces and spin moments are solved by integration: When the wheel slips, the adhesion coefficient is calculated as follows: Where ξ is the adhesion coefficient; F Q is the traction or braking force; F d is the wheel-rail adhesion; Q is the wheel-rail normal force; The wheel-rail adhesion coefficient is observed by the observer: Where n is the number of wheel pairs, is the observed value of wheel-rail adhesion, and its expression is: Operator The calculation formula is obtained by solving the following equation: Where, is the equivalent traction or braking force at the radius of the wheel rolling circle; λ is the cutoff frequency of the observer low-pass filter; J c is the wheelset moment of inertia; ω n is the wheelset rotation angular velocity; R c is the wheel radius.

4. The anti-skid control method for a high-speed train according to claim 3, characterized in that: In step 3, the wheel-rail longitudinal creep rate is calculated using the wheelset forward speed and wheelset rotational speed: Where, v n is the forward speed of the wheelset.

5. The anti-skid control method for high-speed trains according to claim 4, characterized in that: The step 5 is specifically as follows: After calculating the optimal creep threshold, the traction or braking torque needs to be adjusted in a timely manner to prevent wheel slip and ensure that the wheel-rail longitudinal creep rate tracks the optimal creep threshold in real time. The control effect on the traction or braking torque is only triggered when the wheel-rail longitudinal creep rate exceeds the optimal threshold. The sliding mode control algorithm formula is as follows: s=|s n (t)|-|s o | Where s is the sliding surface, which represents the error between the current creep rate and the optimal creep rate, and s n (t) represents the current creep rate, s o represents the optimal front creep rate; The optimal adhesion traction or braking torque sliding mode control law is: Where, I wy is the wheelset rotational inertia, M v is the total mass of the vehicle body, sgn(s) uses a sign function to suppress high-frequency jitter, and q and k satisfy the following conditions:

Images