High-speed maglev train emergency braking safety control method

Abstract

The application relates to a high-speed maglev train emergency braking safety control method, which comprises the following steps: when the speed of the high-speed maglev train exceeds a maximum speed curve, simultaneously starting an emergency braking trigger process and an emergency braking curve preparation process; the emergency braking trigger process controls the high-speed maglev train to reduce the speed to below the maximum speed curve in the shortest time, and identifies whether the overspeed belongs to an occasional fault of a traction system, if yes, the emergency braking curve preparation process is cancelled, otherwise, an emergency braking execution process is executed; the emergency braking curve preparation process generates an emergency braking curve based on dynamic analysis; and the emergency braking execution process controls the emergency braking device of the train to stop the train to a target point of a current parking area in real time according to the prepared emergency braking curve by continuously tracking the position and speed of the train. Compared with the prior art, the application can control the high-speed maglev train to accurately and safely stop to a current target point under the condition of overspeed.

Description

Technical Field

[0001] This invention relates to the field of safety protection in high-speed maglev operation control systems, and in particular to a safety control method for emergency braking of high-speed maglev trains. Background Technology

[0002] Unlike traditional wheel-rail trains, high-speed maglev trains cannot stop at any point on the track during operation; they must stop at auxiliary parking areas or stations with power supply rails and evacuation passages. The operation control system achieves continuous train operation by adopting a stop point step control strategy. During normal operation, high-speed maglev trains are mainly subjected to three forces: (1) the positive or negative traction force from the linear synchronous motor (i.e., conventional braking force); (2) inherent resistances such as air resistance, electromagnetic eddy current resistance, and onboard power grid resistance; and (3) additional resistance introduced by the ramp. For a single run of the maglev train, the operation control system needs to notify the traction control system in advance of the set operating route and the maximum allowable speed limit. After preparing the traction curve, the traction control system drives the train to run under the specified route and speed limit conditions specified by the operation control system through the control converter, and finally stops at the parking point designated by the operation control system. When the train speed exceeds the maximum speed curve allowed by the operation control system, the trackside safety computer of the operation control system is responsible for cutting off traction, and the onboard safety computer of the operation control system is responsible for initiating emergency braking and controlling the train to stop at the current parking point.

[0003] Eddy current braking is activated when the train speed is above 10 km / h. At speeds not exceeding 150 km / h, the attraction of the eddy current electromagnet causes the wear plate to contact the guide rail, generating friction. Below 10 km / h, the eddy current braking force is negligible; therefore, the eddy current braking is deactivated, and the skid is lowered, relying on the friction between the skid and the rail to slide to the stopping area. Eddy current braking, wear plate braking, and skid braking together constitute the emergency braking force of the entire vehicle.

[0004] Emergency braking safety control is a complex control problem in the high-speed maglev operation control system, involving the integrated implementation of emergency braking devices such as eddy current braking, wear plates, and skids. The goal is to safely stop the train in the current stopping area (station or auxiliary stopping area ASA) and as close as possible to the target point (DP) of that stopping area. Although some scholars at home and abroad have conducted research on emergency braking related to high-speed maglev, for example, Chinese patent CN112706802A discloses a method and device for maglev train safety protection. By setting speed-related constraints, including instantaneous overspeed time thresholds and acceleration thresholds between two adjacent speed measuring points, the target position and speed parameters obtained through data fusion are acquired, and safety protection curves and train control curves are calculated to ensure that the maglev train stops safely on lines with power supply rails throughout. However, this method solves the problem of flexible parking, but cannot achieve precise parking in a designated area. Furthermore, when applied to engineering applications, there are still the following difficulties that need to be overcome: (1) It cannot achieve a feasible solution through iterative, learning, or simulation operation methods, but must provide an immediate and safe control method; (2) It cannot only consider normal operating conditions, but must consider the operating conditions under the most unfavorable safe braking conditions; (3) It cannot exceed the parking area and should be as close as possible to the target point of the parking area. Summary of the Invention

[0005] The purpose of this invention is to provide an emergency braking safety control method for high-speed maglev trains. This method can be deployed on an onboard safety computer, enabling high-speed maglev trains to accurately and safely stop at the current stopping point in case of overspeed.

[0006] The objective of this invention can be achieved through the following technical solutions: A safety control method for emergency braking of a high-speed maglev train, the method includes an emergency braking triggering process, an emergency braking curve preparation process, and an emergency braking execution process. When the speed of the high-speed maglev train exceeds the maximum speed curve, the emergency braking triggering process and the emergency braking curve preparation process are started simultaneously. The emergency braking triggering process controls the high-speed maglev train to reduce its speed to below the maximum speed curve in the shortest possible time, and identifies whether the speeding is an occasional fault of the traction system. If it is an occasional fault, the emergency braking curve preparation process is canceled; otherwise, the emergency braking execution process is executed. The emergency braking curve preparation process generates an emergency braking curve based on dynamic analysis, and the calculated line range is from the current position of the train to the target point of the current stopping area. The emergency braking execution process, based on the emergency braking curve prepared during the emergency braking curve preparation process, continuously tracks the position and speed of the train and controls the train's emergency braking device in real time to bring the train to an emergency stop at the target point of the current stopping area.

[0007] The emergency braking triggering process specifically includes the following steps: When the speed of the high-speed maglev train exceeds the maximum speed curve, it is first assumed that the traction system is in an intermittent fault, traction is cut off, and a temporary traction cut-off time window is reserved. After confirming traction cutoff, 100% eddy current braking is initiated. If the speed of the high-speed maglev train is still higher than the maximum speed curve after the temporary traction cutoff time window has expired, it indicates that the speeding is not an occasional fault of the traction system, and the emergency braking control process is triggered. If the speed of the high-speed maglev train has not exceeded the maximum speed curve, the eddy current braking is deactivated, the traction power supply is connected, and a temporary traction connection time window is reserved. If the speed of the high-speed maglev train exceeds the maximum speed curve again within the temporary traction connection time window, it indicates that the speeding is not an occasional fault of the traction system. After traction is cut off, the emergency braking control process is triggered. If the speed of the high-speed maglev train does not exceed the maximum speed curve within the temporary traction connection time window, or if a signal for the target point of the parking area is received, the emergency braking curve preparation process is canceled and the emergency braking triggering process ends. That is, there is no need to implement emergency braking to stop the train at the target point of the current parking area.

[0008] The specific method for generating the emergency braking curve based on dynamic analysis is as follows: The resultant force on the high-speed maglev train under emergency braking conditions is determined by force analysis, and the resultant force formula is revised according to the most unfavorable condition assumption. Based on the revised resultant force formula, combined with relevant parameters of the maglev system, the deceleration process during train operation is deduced in reverse by taking the target point of the current parking area as the starting point and the current position of the center point of the high-speed maglev train as the ending point, and the emergency braking curve is calculated by reverse calculation.

[0009] The process of generating the emergency braking curve simultaneously satisfies the following assumptions: The high-speed maglev train is fully loaded. The tailwind speed is a preset fixed value; The worst-case scenario assumptions are: a predetermined number of brake magnets malfunction; icing occurs on the functional surfaces of the track; and a predetermined number of skids in each car are not deployed during gliding.

[0010] The formula for the resultant force is expressed as follows: ; in, For air resistance, The electromagnetic eddy current resistance on the guide rails on both sides of the track, The operating resistance of the vehicle-mounted DC generator, Add resistance to the ramp, For eddy current braking force, For the friction force of the wear plate, This refers to the friction force of the skid plate.

[0011] The revision of the resultant force formula based on the most unfavorable condition assumptions specifically includes: revising the air resistance by considering wind speed; revising the eddy current braking force and wear plate friction by considering the failure rate of the eddy current brake magnets in each car; and revising the skid plate friction by considering the skid failure rate in each car.

[0012] The data structure of the emergency braking curve is represented as an array of distance and speed point pairs, where the distance in the array is the distance between the train's center point and the target point in the current stopping area, and the speed in the array is the desired speed.

[0013] The control strategy for the emergency braking process is as follows: when the speed of the high-speed maglev train is higher than the preset speed, eddy current braking is activated, and the level of eddy current braking is controlled according to the distance between the high-speed maglev train and the target point and the desired speed; when the train speed is lower than the preset speed, the eddy current braking system is deactivated, a disembarkation control signal is output, and the train slides to the vicinity of the target point in the parking area by friction with a skid.

[0014] During the emergency braking process, the important variables that need to be set include: a first distance variable, used to store the distance between the center point of the high-speed maglev train and the target point in the previous task processing cycle; a second distance variable, used to store the theoretically calculated distance between the center point of the train and the target point, calculated based on the emergency braking curve; a stability coefficient, used to control the frequency of adjusting the eddy current braking level, and when the deviation ratio between the theoretically calculated displacement and the actual displacement is lower than the stability coefficient, it is not necessary to adjust the eddy current braking level; and a control signal for the eddy current braking level, which controls the ratio of the actual braking force output to the maximum eddy current braking force by setting a set of values, where each value corresponds to a different level of eddy current braking.

[0015] The emergency braking execution process specifically includes the following steps: Output the control signal for the initial eddy current braking level; Set variable S to represent the distance between the center point of the high-speed maglev train and the target point in the current task processing cycle; set a first distance variable, a second distance variable, and a stability coefficient, wherein the initial value of the first distance variable is set to the distance between the train and the target point when entering the emergency braking execution process; When the next task processing cycle arrives, the distance between the train's center point and the target point is calculated and saved to variable S; based on variable S, the distance interval corresponding to the emergency braking curve is found, and the corresponding expected speed is determined; Based on the desired speed and distance range, calculate the ideal deceleration required when the train is at a distance S from the target point; The theoretical distance of the train is calculated based on the first distance variable, the calculated ideal deceleration, and the task processing cycle length, and stored in the second distance variable; the difference between the first distance variable and variable S is calculated to obtain the actual displacement, and the difference between the first distance variable and the second distance variable is calculated to obtain the theoretical displacement. Calculate the product of the difference between 1 and the stability coefficient and the theoretically calculated displacement. Adjust the control signal of the eddy current braking level according to the actual displacement and the magnitude of the product, and output it to the eddy current controller for eddy current braking control. Determine if the train's current speed is lower than the preset speed. If so, output a drop signal, turn off the eddy current brake, release the useful memory space occupied by the emergency braking curve, and end the emergency braking execution process. Otherwise, assign the value of variable S to the first distance variable and wait for the next task processing cycle.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention considers the operating conditions under the most unfavorable safe braking conditions and the problem of occasional faults in the traction system. It clearly decomposes the emergency braking process into an emergency braking triggering process, an emergency braking curve preparation process, and an emergency braking execution process. When the train speed exceeds the maximum speed curve, the emergency braking triggering process and the emergency braking curve preparation process are initiated simultaneously. Based on the line range from the train's current position to the target point of the current stopping area, dynamic analysis is performed to generate an emergency braking curve. During this process, occasional faults in the traction system are identified to avoid unnecessary braking. Finally, by continuously tracking the train's position and speed, emergency braking devices such as eddy current braking, wear plate braking, and skid braking are controlled in real time. Thus, under the consideration of the most unfavorable safe braking conditions, an immediate and safe control method is achieved to ensure that the train safely stops at the current stopping area without exceeding the stopping area range and is as close as possible to the target point of the stopping area. This solves the safety hazards and the jitter problem of eddy current braking level output in the prior art, and enables the train to stop accurately and safely at the current stopping point when the train is speeding. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a state diagram of the emergency braking triggering process of the present invention; Figure 3 A state diagram illustrating the preparation process of the emergency braking curve for this invention; Figure 4 This is a schematic diagram illustrating the derivation of the confidence interval from the train to the target point when using skid braking in this invention; Figure 5 This is a flowchart of the emergency braking execution process of the present invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0019] This embodiment provides a safety control method for emergency braking of a high-speed maglev train, such as... Figure 1 As shown, the method includes an emergency braking triggering process, an emergency braking curve preparation process, and an emergency braking execution process. When the speed of the high-speed maglev train exceeds the maximum speed curve, the emergency braking triggering process and the emergency braking curve preparation process are started simultaneously. The emergency braking trigger process controls the high-speed maglev train to reduce its speed to below the maximum speed curve in the shortest possible time, and identifies whether the speeding is due to an intermittent fault in the traction system. If it is an intermittent fault, the emergency braking curve preparation process is canceled; otherwise, the emergency braking execution process is executed. The emergency braking curve preparation process generates an emergency braking curve based on dynamic analysis, and the calculated line range is from the current position of the train to the target point of the current stopping area; The emergency braking execution process, based on the emergency braking curve prepared during the emergency braking curve preparation process, continuously tracks the position and speed of the train and controls the emergency braking device of the train in real time to bring the train to an emergency stop at the target point of the current stopping area.

[0020] (1) Emergency braking triggering process The main task of the emergency braking triggering process is to reduce the train speed to below the maximum speed curve in the shortest possible time, identify whether the speeding is due to an occasional malfunction of the traction system, and decide whether to make an emergency stop to the current stopping point.

[0021] The emergency braking triggering process is implemented using a state diagram, such as... Figure 2 As shown. The entry condition for the emergency braking triggering process is that the train speed exceeds the maximum speed curve, which includes four key states: temporary disconnection state, formal traction disconnection state, temporary traction connection state, and formal traction connection state.

[0022] 1. Temporary disconnection status When the speed of the high-speed maglev train exceeds the maximum speed curve, it is assumed that the traction system is in an intermittent fault, traction is cut off, and a temporary traction cut-off time window is reserved.

[0023] After confirming traction cutoff, 100% eddy current braking is initiated. If the speed of the high-speed maglev train is still higher than the maximum speed curve after the temporary traction cutoff time window has expired, it enters the formal cutoff state; if the speed of the high-speed maglev train has not exceeded the maximum speed curve, it enters the temporary traction connection state.

[0024] 2. Formal traction disconnection status If the system enters the formal traction disconnection state, it indicates that the speeding incident was not an occasional malfunction of the traction system. If traction is engaged, traction disconnection will be executed first, followed by triggering the emergency braking control process.

[0025] 3. Temporary traction connection status Upon entering the temporary traction engagement state, the eddy current brake is immediately deactivated, traction power supply is activated, and a temporary traction engagement time window is maintained. If the train speed exceeds the maximum speed curve again within the temporary traction engagement time window, it indicates that the overspeeding is not an occasional fault of the traction system, and the train enters the formal traction disconnection state; conversely, if the train speed does not exceed the maximum speed curve, or a stop point step signal is received, the train enters the formal traction engagement state.

[0026] 4. Formal traction connection status Once the train enters the formal traction engagement state, the overspeeding behavior is characterized as an occasional traction system malfunction. The impact of this malfunction can be ignored. The preparation process for the emergency braking curve is cancelled, and the emergency braking triggering process is terminated. The emergency braking process that would stop the train in the current parking area is no longer implemented.

[0027] (2) Emergency braking curve preparation process The main task of the emergency braking curve preparation process is to calculate the emergency braking curve based on dynamic analysis.

[0028] The emergency braking curve preparation process is implemented using a state diagram, such as... Figure 3 As shown. The entry condition for the emergency braking curve preparation process is that the train speed exceeds the maximum speed curve, which includes three key states: initialization state, emergency braking curve calculation state, and emergency braking curve cancellation state.

[0029] 1. Initialization state Upon entering this state, variables are initialized and the storage space required for the emergency braking curve is allocated.

[0030] 2. Emergency Braking Curve Calculation Status Upon entering this state, the emergency braking curve is calculated based on dynamic analysis using the storage space allocated during initialization. Taking the target point of the current stopping area as the starting point (i.e., the calculation source point) and the current position of the train's center point as the ending point, the safe braking curve is calculated by reverse-engineering the deceleration process during train operation.

[0031] The safety braking curve requires high safety standards, and the probability of danger must be controlled within 10 per hour. -8Therefore, this embodiment makes the following assumptions when calculating the safe braking curve: a. The train was fully loaded; b. Downwind speed 25m / s; c. Four brake magnets are faulty (there are eight brake magnets in each car). d. Icing occurs on the functional surfaces of the track; e. During the gliding process, 5 skis were not deployed (each car has 16 skis).

[0032] Among them, c, d, and e are the most unfavorable assumptions.

[0033] Under emergency braking conditions, the maglev train experiences the resultant force of basic resistance, additional resistance, and emergency braking force. The basic resistance, which is the resistance generated when the train runs on open terrain or a straight, level road, includes air resistance. Electromagnetic eddy current resistance on the guide rails on both sides of the track and the operating resistance of the vehicle-mounted DC generator Additional resistance refers to the extra resistance generated when a train runs on non-open terrain or non-straight tracks. Here, we mainly consider the additional resistance caused by gradients. We can ignore the minor additional drag from curves and air resistance from tunnels. Emergency braking forces mainly include eddy current braking forces. Wear plate friction force Friction force of the skid The net force acting on a maglev train under emergency braking conditions is: .

[0034] Regarding these mechanical formulas, empirical formulas commonly used by industry professionals and scholars are employed. Subsequently, the resultant force formulas are revised based on the worst-case scenario assumptions, including: revisions considering wind speed's impact on air resistance; revisions considering the failure rate of eddy current brake magnets in each car to affect eddy current braking force and wear plate friction; and revisions considering the skid failure rate in each car to affect skid plate friction. The specific implementation process is as follows: Air resistance without considering wind speed As shown in formula (1a), the unit is KN .

[0035] (1a) In the formula: For train speed, m / s ; This refers to the number of train cars.

[0036] Assuming the worst-case scenario, wind speed needs to be taken into account, i.e., a tailwind of 25. m / sTherefore, the formula used when calculating the emergency braking curve is the modified formula (1b) of formula (1a).

[0037] (1b) Electromagnetic eddy current resistance As shown in formula (2), the unit is KN .

[0038] (2) Operating resistance of vehicle-mounted DC generator As shown in formula (3), the unit is KN .

[0039] (3) The operating resistance of the on-board DC generator is a piecewise function. It can be ignored when the train speed is below 20 km / h; it is basically a fixed value between 20 km / h and 70 km / h; and it is inversely proportional to the speed when the train speed is above 70 km / h.

[0040] Additional resistance of ramps The calculation is shown in formula (4).

[0041] (4) In the formula: The weight of the train is in tons. The acceleration due to gravity is 9.8 m / s². 2 ; For in position The gradient value corresponding to the track section at that time. Under the worst-case scenario assumption, the train weight M is selected here as the weight of the train when fully loaded.

[0042] Eddy current braking force in emergency braking Wear plate friction force Friction force of the skid The calculation is expressed as shown in formulas (5) to (7).

[0043] Eddy braking force As shown in formula (5), the unit is KN .

[0044] (5) In the formula: -Number of train cars; w= / c , - Train speed (km / h) c - Characteristic speed value (empirical value is 200 km / h); - Effective percentage of braking units. Assuming the train has 5 carriages, each with 8 braking magnets, and assuming the worst-case scenario for safe braking (i.e., a total of 4 braking magnets fail), then... =0.9. This formula is used to calculate the maximum level of eddy current braking force. The actual output eddy current braking force during eddy current braking depends on the control signal for the eddy current braking level.

[0045] Wear plate friction force As shown in formula (6), the unit KN .

[0046] (6) In the formula: The coefficient of sliding friction; The pressure applied by the train to the brake wear plate; This represents the effective percentage of the braking units. Assuming the train has 5 carriages, each with 8 braking magnets, and assuming the worst-case scenario for safe braking (i.e., a total of 4 braking magnets fail), then... =0.9.

[0047] Friction of the skid plate As shown in formula (7), the unit is KN .

[0048] (7) In the formula: The coefficient of sliding friction; The effective sliding friction rate is the ratio of the number of suspension frames actually deployed to the total number of suspension frames.

[0049] As the final stage of emergency braking, the task of emergency braking is to deactivate eddy current braking when the train speed is less than 10 km / h and stop the train in the current stopping area by using a skid to bring it to a stop through the friction between the skid and the track. This requires consideration of two operating conditions: emergency braking under normal conditions and emergency braking under the most unfavorable conditions.

[0050] For emergency braking under normal conditions, i.e., the track surface is dry and all skids are effective, the empirical value of the average sliding friction coefficient is given when the maglev train is coasting at a speed less than 10 km / h. =0.24, effective sliding friction rate =1. Therefore, the braking distance of the train calculated according to kinematics is no greater than 2m.

[0051] For the most unfavorable emergency braking condition, i.e., the track surface is icy and five skids are not deployed during skid-assisted gliding, the empirical value of the average sliding friction coefficient for the maglev train when gliding at speeds less than 10 km / h is given. =0.024. Assuming the train has 5 carriages, and each carriage has 16 skis, then the effective sliding friction rate is... =75 / 80. Therefore, the braking distance of the train calculated according to kinematics is no greater than 18m.

[0052] Combining the two operating conditions, the average braking distance of the train is 10 meters. Therefore, when calculating the emergency braking curve, a position 10 meters from the target point is chosen as the landing condition. Figure 4 It can be deduced that when using skid braking at speeds less than 10 km / h, the confidence interval for the train to reach the target point is (-8m, 8m).

[0053] Based on the revised resultant force formula and combined with relevant parameters of the maglev system, the target point of the current parking area is taken as the starting point (i.e. the calculation source point), and the current position of the center point of the high-speed maglev train is taken as the ending point. The deceleration process during the train operation is deduced in reverse, and the emergency braking curve is calculated by reverse calculation.

[0054] The data structure of the emergency braking curve is represented as an array of <distance, speed> point pairs, i.e., < , The array consists of point pairs, where distance refers to the distance between the train's center point and the target point in the current stopping area, and speed refers to the desired speed. The data format for the emergency braking curve is as follows: < , >、< , >……< , >、< , >…… The train's distance and speed are both 0 at the initial moment, that is... =0, =0. When performing reverse-engineering of the train operation, a relatively small computational time step is selected. Assume the train is on the... , No. The distance and speed corresponding to +1 task processing cycle are respectively < , > and < , > This indicates that the train experienced an incident from arrive The displacement, velocity from Become The kinematic equations governing the train's operation can then be expressed as: (8) In the formula, The current acceleration of the train is in m / s². 2 ; The revised combined force currently affecting the train; The train's current speed is in m / s; The speed at the next moment; To calculate the time step; The distance between the train and the target point at the current moment, in meters (m); This represents the distance between the train and the target point at the next moment.

[0055] 3. Emergency braking curve cancellation status After entering the emergency braking curve cancellation state, the calculation of the emergency braking curve stops, and the storage space allocated for the emergency braking curve during the initialization state is released. The emergency braking process to safely stop the maglev train in the current parking area is no longer implemented.

[0056] (3) Emergency braking execution process The emergency braking execution process is initiated by the emergency braking triggering process. Its main task is to continuously track the position and speed of the train and bring the train to an emergency stop at the current stopping point by controlling the emergency braking device in real time, based on the emergency braking curve data generated during the emergency braking preparation process.

[0057] The control strategy for emergency braking is as follows: When the high-speed maglev train's speed exceeds 10 km / h, eddy current braking is activated. The level of eddy current braking is controlled based on the distance between the high-speed maglev train and the target point, as well as the desired speed. The eddy current braking controller can output eight levels of eddy current braking force, i.e., levels 0-7. According to safety design principles, level 0 represents the maximum output of eddy current braking force, and level 7 represents zero output of eddy current braking force. When the train speed is below 150 km / h, the eddy current electromagnet is in complete contact with the guide rail, and the emergency braking force is composed of the eddy current braking force and the braking friction force generated by the brake wear plate. When the train speed is below 10 km / h, the eddy current braking system is deactivated, a disembarkation control signal is output, and the train slides to the vicinity of the target point in the stopping area via skid friction.

[0058] During the emergency braking process, the important variables that need to be set include: (1) the first distance variable S0, which is used to store the distance between the center point of the high-speed maglev train and the target point in the previous task processing cycle; (2) the second distance variable S1, which is used to store the theoretical calculated distance between the center point of the train and the target point calculated based on the emergency braking curve; and (3) the parameter variable k. s, representing the stability coefficient, is used to control the frequency of adjusting the eddy current braking level. Too frequent adjustments will significantly reduce comfort. When the ratio between actual displacements and theoretically calculated displacements is within [1-k...], the stability coefficient is determined. s ,1+k s When there is no need to adjust the eddy current braking level, for example, setting it to 0.1 represents 10%; (4) Variable u, which is a control parameter, represents the control signal of the eddy current braking level. Its value set is {0,1,2,3,4,5,6,7}. The ratio of the actual braking force output to the maximum eddy current braking force is (7-u) / 7.

[0059] The core algorithm of the emergency braking execution process is: setting the task processing cycle; in each task processing cycle, determining which emergency braking device to use, using a skid when the speed is no more than 10km / h, otherwise using eddy current braking; if eddy current braking is used, the main processing step is how to adjust the eddy current braking level.

[0060] like Figure 5 As shown, the emergency braking process specifically includes the following steps: S1, outputs the control signal u=0 for the initial eddy current braking level; S2 sets the variable S to represent the distance between the center point of the high-speed maglev train and the target point in the current task processing cycle, which needs to be tracked and calculated in each task processing cycle; the first distance variable S0 is set to store the distance between the train and the target point in the previous time cycle, with the initial value being the distance between the train and the target point when entering the emergency braking process; the second distance variable S1 is set to represent the ideal calculated distance obtained from the emergency braking curve; the parameter variable k is set. s , representing the stability coefficient, is used when the ratio of the deviation between the theoretically calculated displacement and the actual displacement is less than k. s There is no need to adjust the eddy current braking level; in this embodiment, it is set to 0.1.

[0061] S3, when the next task processing cycle T (default 200ms) is reached, calculate the distance between the train center point and the target point and save it to variable S; find the distance interval corresponding to the emergency braking curve based on variable S. , Determine the corresponding expected speed. , Since the point-to-point array of the emergency braking curves is sorted by distance, a standard binary search method is used here to improve search efficiency.

[0062] S4, according to the calculation formula Calculate the ideal deceleration required when the distance between the train and the target point is S; S5, according to the calculation formula Calculate the theoretical distance of the train and store it in the second distance variable S1; calculate the difference between the first distance variable S0 and variable S to obtain the actual displacement (S0-S); calculate the difference between the first distance variable S0 and the second distance variable S1 to obtain the theoretical displacement (S0-S1).

[0063] S6, if (S0-S)<(1-k) s If (S0-S1) > (1+k), it indicates that the braking force is too large. Further checks are needed to determine if u is less than 7. If u < 7, then u = u + 1; if (S0-S1) > (1+k), then u = u + 1. s If the braking force is too small, we need to further determine whether u is greater than 0. If u>0, then u=u-1; otherwise, u remains unchanged.

[0064] S7 outputs the eddy current braking level u to the eddy current controller.

[0065] S8: Determine if the current speed of the train is not greater than 10km / h. If not, assign the current distance S of the train to S0, i.e., S0=S, and then jump to step S3 to wait for the next task processing cycle. If yes, output the derailment signal, turn off the eddy current brake, release the useful memory space occupied by the emergency braking curve, and the process ends.

[0066] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A safety control method for emergency braking of a high-speed maglev train, characterized in that, The method includes an emergency braking triggering process, an emergency braking curve preparation process, and an emergency braking execution process. When the speed of the high-speed maglev train exceeds the maximum speed curve, the emergency braking triggering process and the emergency braking curve preparation process are started simultaneously. The emergency braking triggering process controls the high-speed maglev train to reduce its speed to below the maximum speed curve in the shortest possible time, and identifies whether the speeding is an occasional fault of the traction system. If it is an occasional fault, the emergency braking curve preparation process is canceled; otherwise, the emergency braking execution process is executed. The emergency braking curve preparation process generates an emergency braking curve based on dynamic analysis, and the calculated line range is from the current position of the train to the target point of the current stopping area. The emergency braking execution process, based on the emergency braking curve prepared during the emergency braking curve preparation process, continuously tracks the position and speed of the train and controls the emergency braking device of the train in real time to bring the train to an emergency stop at the target point of the current stopping area. The emergency braking triggering process specifically includes the following steps: When the speed of the high-speed maglev train exceeds the maximum speed curve, it is assumed that the traction system is in an intermittent fault, traction is cut off, and a temporary traction cut-off time window is reserved. After confirming traction cutoff, 100% eddy current braking is initiated. If the speed of the high-speed maglev train is still higher than the maximum speed curve after the temporary traction cutoff time window has expired, it indicates that the speeding is not an occasional fault of the traction system, and the emergency braking control process is triggered. If the speed of the high-speed maglev train has not exceeded the maximum speed curve, the eddy current braking is deactivated, the traction power supply is connected, and a temporary traction connection time window is reserved. If the speed of the high-speed maglev train exceeds the maximum speed curve again within the temporary traction connection time window, it indicates that the speeding is not an occasional fault of the traction system. After traction is cut off, the emergency braking control process is triggered. If the speed of the high-speed maglev train does not exceed the maximum speed curve within the temporary traction connection time window, or if a signal for the target point of the parking area is received, the emergency braking curve preparation process is canceled and the emergency braking triggering process ends. That is, there is no need to implement emergency braking to stop the train at the target point of the current parking area.

2. The emergency braking safety control method for a high-speed maglev train according to claim 1, characterized in that, The specific method for generating the emergency braking curve based on dynamic analysis is as follows: The resultant force on the high-speed maglev train under emergency braking conditions is determined by force analysis, and the resultant force formula is revised according to the most unfavorable condition assumption. Based on the revised resultant force formula, combined with relevant parameters of the maglev system, the deceleration process during train operation is deduced in reverse by taking the target point of the current parking area as the starting point and the current position of the center point of the high-speed maglev train as the ending point, and the emergency braking curve is calculated by reverse calculation.

3. The emergency braking safety control method for a high-speed maglev train according to claim 2, characterized in that, The process of generating the emergency braking curve simultaneously satisfies the following assumptions: The high-speed maglev train is fully loaded. The tailwind speed is a preset fixed value; The worst-case scenario assumptions are: a predetermined number of brake magnets malfunction; icing occurs on the functional surfaces of the track; and a predetermined number of skids in each car are not deployed during gliding.

4. The emergency braking safety control method for a high-speed maglev train according to claim 2, characterized in that, The formula for the resultant force is expressed as follows: ； in, For air resistance, The electromagnetic eddy current resistance on the guide rails on both sides of the track, The operating resistance of the vehicle-mounted DC generator, Add resistance to the ramp, For eddy current braking force, For the friction force of the wear plate, This refers to the friction force of the skid plate.

5. The emergency braking safety control method for a high-speed maglev train according to claim 4, characterized in that, The revision of the resultant force formula based on the worst-case assumptions specifically includes: revising the air resistance by considering wind speed; revising the eddy current braking force and wear plate friction by considering the failure rate of the eddy current brake magnets in each car; and revising the skid plate friction by considering the skid failure rate in each car.

6. The emergency braking safety control method for a high-speed maglev train according to claim 1, characterized in that, The data structure of the emergency braking curve is represented as an array of distance and speed point pairs, where the distance in the array is the distance between the train's center point and the target point in the current stopping area, and the speed in the array is the desired speed.

7. The emergency braking safety control method for a high-speed maglev train according to claim 1, characterized in that, The control strategy for the emergency braking process is as follows: when the speed of the high-speed maglev train is higher than the preset speed, eddy current braking is activated, and the level of eddy current braking is controlled according to the distance between the high-speed maglev train and the target point and the desired speed; when the train speed is lower than the preset speed, the eddy current braking system is deactivated, a disembarkation control signal is output, and the train slides to the vicinity of the target point in the parking area by friction with a skid.

8. The emergency braking safety control method for a high-speed maglev train according to claim 1, characterized in that, During the emergency braking process, the important variables that need to be set include: a first distance variable, used to store the distance between the center point of the high-speed maglev train and the target point in the previous task processing cycle; a second distance variable, used to store the theoretically calculated distance between the center point of the train and the target point, calculated based on the emergency braking curve; a stability coefficient, used to control the frequency of adjusting the eddy current braking level, and when the deviation ratio between the theoretically calculated displacement and the actual displacement is lower than the stability coefficient, it is not necessary to adjust the eddy current braking level; and a control signal for the eddy current braking level, which controls the ratio of the actual braking force output to the maximum eddy current braking force by setting a set of values, where each value corresponds to a different level of eddy current braking.

9. The emergency braking safety control method for a high-speed maglev train according to claim 8, characterized in that, The emergency braking execution process specifically includes the following steps: Output the control signal for the initial eddy current braking level; Set variable S to represent the distance between the center point of the high-speed maglev train and the target point in the current task processing cycle; set a first distance variable, a second distance variable, and a stability coefficient, wherein the initial value of the first distance variable is set to the distance between the train and the target point when entering the emergency braking execution process; When the next task processing cycle arrives, the distance between the train's center point and the target point is calculated and saved to variable S; based on variable S, the distance interval corresponding to the emergency braking curve is found, and the corresponding expected speed is determined; Based on the desired speed and distance range, calculate the ideal deceleration required when the train is at a distance S from the target point; The theoretical distance of the train is calculated based on the first distance variable, the calculated ideal deceleration, and the task processing cycle length, and stored in the second distance variable; the difference between the first distance variable and variable S is calculated to obtain the actual displacement, and the difference between the first distance variable and the second distance variable is calculated to obtain the theoretical displacement. Calculate the product of the difference between 1 and the stability coefficient and the theoretically calculated displacement. Adjust the control signal of the eddy current braking level according to the actual displacement and the magnitude of the product, and output it to the eddy current controller for eddy current braking control. Determine if the train's current speed is lower than the preset speed. If so, output a drop signal, turn off the eddy current brake, release the useful memory space occupied by the emergency braking curve, and end the emergency braking execution process. Otherwise, assign the value of variable S to the first distance variable and wait for the next task processing cycle.

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