Stator segment step-changing control method and system

Abstract

The present invention provides a stator segment step-changing control method for a maglev train, comprising: in response to the train arriving at a step-changing point, determining a first current change rate and a second current change rate based on the current speed of the train, the length of the train and the weight of a single carriage, the motor back-electromotive force coefficient of a single carriage on one side and at unit speed of the train, and a characteristic time constant of a stator segment step-changing control system, wherein the first current change rate is proportional to the weight of the single carriage and inversely proportional to the current speed, the motor back-electromotive force coefficient and the characteristic time constant, and the second current change rate is proportional to the weight of the single carriage and inversely proportional to the motor back-electromotive force coefficient; and controlling the current drop and rise of the stator segment during the step-changing process according to the smaller one of the first current change rate and the second current change rate.

Description

Technical Field

[0001] The invention relates to a high-speed maglev transportation traction control system which adopts a ground long-stator linear motor to drive a maglev train, and in particular to a stator segment step-changing control method and system. Background Art

[0002] In order to improve power supply efficiency and reduce losses, the long-stator linear motor used for traction maglev trains adopts a segmented power supply method, that is, the motor stator along the line is divided into several small sections, and only the stator winding of the section where the train is located is energized. When the train crosses from one stator segment to another, the traction motor control unit switches the output current of the traction inverter from the previous stator segment to the next stator segment through the feeder cable to achieve the purpose of driving the train. This is achieved by controlling the vacuum contactors in the stator switch station arranged along the track line to alternately connect or disconnect. This method of switching the feed current from one stator segment to another is called the stator segment step-changing method.

[0003] The stator segments of the tracks on both sides are arranged in a staggered structure. When the train is not in a step-changing state, the tracks on both sides of the train are equivalent to having a linear motor working independently. When the train is in the step-changing process, the traction motor control unit calculates the appropriate step-changing time in real time according to the current position and speed of the train. First, the current of the stator segment that the vehicle is leaving is turned off and dropped to zero, and then the current of the stator segment that the vehicle is entering is turned on and increased. At this time, it is equivalent to only one side of the motor working normally, and the train traction will pulsate and decrease, which will cause power loss of the supply current on the stator segment and reduce passenger comfort.

[0004] In order to reduce power loss, the current on the stator segment should rise and fall as quickly as possible during the step-changing process. However, if the current changes too quickly, the traction force will change too drastically, which will affect the ride comfort. Therefore, how to limit the rate at which the stator segment current rises and falls during the step-changing process is one of the key technologies for the train to travel efficiently and smoothly between the stator segments. Summary of the invention

[0005] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0006] According to one aspect of the present invention, a stator segment step-changing control method for a train is provided, comprising:

[0007] In response to the train arriving at a step-changing point, determining a first current change rate and a second current change rate based on the current speed of the train, the length of the train and the weight of a single carriage, the motor back-EMF coefficient of a single carriage of the train on one side and at a unit speed, and a characteristic time constant of a stator segment step-changing control system, wherein the first current change rate is proportional to the weight of the single carriage and inversely proportional to the current speed, the motor back-EMF coefficient and the characteristic time constant, and the second current change rate is proportional to the weight of the single carriage and inversely proportional to the motor back-EMF coefficient; and

[0008] The current drop and rise of the stator segment during the step change process are controlled according to the smaller one of the first current change rate and the second current change rate.

[0009] In one example, the first current change rate k1 satisfies the constraint condition:

[0010]

[0011] The second current change rate k2 satisfies the constraint condition:

[0012]

[0013] Among them, U px is the motor back EMF coefficient, v is the current speed, t c is the characteristic time constant, m is the weight of the single carriage, L 车 is the train captain, J max is the maximum allowable value of the impact rate of the train.

[0014] In one example, the first current change rate k1 is The maximum value of the second current change rate k2 is The maximum value of .

[0015] In one example, the J max is set to 0.75.

[0016] In one example, the t c It is the time from when the traction motor control unit issues a command to disconnect the vacuum contactor of the stator switch station corresponding to the current stator segment to when the vacuum contactor of the stator switch station corresponding to the next stator segment performs a closing action and provides status feedback.

[0017] According to another aspect of the present invention, a stator segment step-changing control system for a train is provided, comprising:

[0018] A traction motor control unit is configured to:

[0019] In response to the train arriving at a step-changing point, a first current change rate and a second current change rate are determined based on the current speed of the train, the length of the train and the weight of a single carriage, the motor back-EMF coefficient of a single carriage of the train on one side and at a unit speed, and a characteristic time constant of the stator segment step-changing control system, wherein the first current change rate is proportional to the weight of the single carriage and inversely proportional to the current speed, the motor back-EMF coefficient and the characteristic time constant, and the second current change rate is proportional to the weight of the single carriage and inversely proportional to the motor back-EMF coefficient; and

[0020] The current drop and rise of the stator segment during the step change process are controlled according to the smaller one of the first current change rate and the second current change rate.

[0021] In one example, the first current change rate k1 satisfies the constraint condition:

[0022]

[0023] The second current change rate k2 satisfies the constraint condition:

[0024]

[0025] Among them, U px is the motor back EMF coefficient, v is the current speed, t c is the characteristic time constant, m is the weight of the single carriage, L 车 is the train captain, J max is the maximum allowable value of the impact rate of the train.

[0026] In one example, the first current change rate k1 is The maximum value of the second current change rate k2 is The maximum value of .

[0027] In one example, the J max is set to 0.75.

[0028] In one example, the t c It is the time from when the traction motor control unit issues a command to disconnect the vacuum contactor of the stator switch station corresponding to the current stator segment to when the vacuum contactor of the stator switch station corresponding to the next stator segment performs a closing action and provides status feedback.

[0029] According to another aspect of the present invention, a computer-readable medium is provided, on which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, the above method is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0031] Figure 1 A schematic diagram showing the relationship between devices of a traction control system in a two-step stator-stepping mode according to one aspect of the present invention is shown;

[0032] Figure 2 A schematic timing diagram of a stator segment step-changing process according to one aspect of the present invention is shown;

[0033] Figure 3 A schematic diagram showing a stator segment step-changing state according to one aspect of the present invention;

[0034] Figure 4 A schematic diagram showing a stator segment step-changing state according to one aspect of the present invention;

[0035] Figure 5 A schematic diagram showing a stator segment step-changing state according to one aspect of the present invention;

[0036] Figure 6 A schematic diagram showing a stator segment step-changing state according to one aspect of the present invention; and

[0037] Figure 7 A flow chart of a stator segment step changing method according to one aspect of the present invention is shown. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the aspects described below in conjunction with the accompanying drawings and specific embodiments are only exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0039] Figure 1 The equipment configuration and connection relationship of the high-speed maglev traction system using double-end power supply and two-step step-changing method are shown. Each traction substation contains two sets of traction converters, which pass through the stator switch stations arranged along the line and supply power to the stator segments on the left and right sides of the track through feeder cables. Several vacuum contactors are set in each stator switch station, and each stator switch station corresponds to an SSC (stator switch station control unit). All SSCs between the two traction substations form a communication ring network with the traction motor control units at both ends through optical fibers. They receive instructions from the traction motor control unit and control the action of the vacuum contactor in the corresponding stator switch station, thereby controlling the conduction and disconnection between each stator segment and the converter.

[0040] Figure 2FIG. 2 shows a timing diagram of a stator segment step-changing process according to an aspect of the present invention. Figure 2 As shown in the figure, taking the train center point as the reference point for analysis, the entire step-changing process can include six stages:

[0041] Phase 1), according to the current speed and position of the train, the traction motor control unit controls the converter to reduce the current of the stator segment where the current train is located to 0. Phase 1) takes t1;

[0042] Phase 2), the traction motor control unit issues a command to disconnect the vacuum contactor of the stator switch station corresponding to the current stator segment, and the stator switch station control unit receives the command. Phase 2) takes time t2;

[0043] In stage 3), the vacuum contactor of the stator switch station performs the disconnection action and performs status feedback. The time consumed in stage 3 is t3;

[0044] In stage 4), the traction motor control unit issues a command to close the vacuum contactor of the stator switch station corresponding to the next stator segment, and the stator switch station control unit receives the command. The time taken for stage 4 is t4;

[0045] Phase 5), the stator switch station vacuum contactor performs a closing action and performs status feedback, and the duration of Phase 5) is t5; and

[0046] In stage 6), the traction motor control unit controls the converter to increase the current of the next stator segment to the desired value. The time taken for stage 6 is t6.

[0047] In the above-mentioned step-changing process, limited by the electrical and mechanical characteristics of the system, t2, t3, t4, and t5 are fixed values. The current drop time t1 of the front stator segment and the current rise time t2 of the rear stator segment depend on the current change rate of the step-changing process. Figure 2 Middle D r is the distance from the step-changing trigger point to the junction of the two stator segments, T is the total time from the triggering of the step-changing command to the end of the entire step-changing process, T = t1 + t2 + t3 + t4 + t5 + t6.

[0048] Passenger riding comfort is usually evaluated by the rate of change of acceleration, i.e., the impact rate J. In order to ensure comfort, the impact rate J cannot be greater than the threshold J. max .

[0049]

[0050] Ignoring the influence of line slope and other conditions, the acceleration can be calculated by the following formula (2):

[0051]

[0052] Where F L 、FR are the thrust of the left and right motors, F Z is the train resistance (negative value during acceleration and positive value during braking), N is the number of train sets, and m is the weight of a single car.

[0053] Without considering the influence of magnetic saturation and line parameter changes, that is, the traction force changes linearly with the coupling length of the on-board electromagnet and the stator segment, the motor thrust F X It can be calculated by the following formula:

[0054]

[0055] Where v is the train speed, I S is the stator segment current, U P is the motor back EMF, U px is the motor back electromotive force of a single car on one side and at unit speed, that is, the back electromotive force coefficient, and η is the ratio of the train length covering the current stator segment.

[0056] The resistance of the train mainly consists of three parts: air resistance, eddy current resistance and the braking force generated by the generator, which is only related to the number of train formations (fixed value) and speed. Since the stator segment step-changing time is much shorter than the train running time on a stator segment, the following description assumes that the train speed does not change during the step-changing process, and the stator segment current on the same side of the track is equal before and after the step-changing. Therefore, the train resistance has nothing to do with the acceleration change.

[0057] Assuming that the stator segment on the step-changing side is the left stator segment, and the current of the right stator segment remains unchanged during the step-changing process, substituting equations (2) and (3) into equation (1), it can be obtained that the step-changing process should satisfy the following formula:

[0058]

[0059] For the convenience of analysis, the following critical situation is considered: when the locomotive is at the stator segment boundary, the step change is triggered, and when all trains leave the previous stator segment, the whole step change process is completed. Figure 3 As shown, at this time there is v N =L 车 / T.

[0060] Several situations are described below. Since the step-changing process of the front and rear stator segments is completely symmetrical, all the following descriptions are based on the current drop process of the front stator segment.

[0061] (I) Train speed before step change v ≥ v N :

[0062] In case a, before the train enters the next stator section, the current in the previous stator section has dropped to zero. This situation can be explained by Figure 4 Shown. Figure 4It can be seen from the figure that during the current drop (the train runs from position ① to position ② during t1), the train is completely covered on the previous stator segment. At this time, D r Should be greater than or equal to the distance traveled by the train in the t1 period (the distance between position ① and position ②, equal to ) plus half the vehicle length (the distance between position ② and position ③, which is 1 / 2L 车 ), that is, the following relationship is satisfied:

[0063]

[0064] at this time:

[0065]

[0066] According to formula (4), it can be calculated that the current drop slope k should satisfy:

[0067]

[0068] In case b, when the train enters the next stator section, the current in the previous stator section has not yet dropped to zero. Figure 5 As shown. Figure 5 It can be seen that during the current drop process (the train runs from position ① to position ③ during t1), the train does not always cover the previous stator segment completely. At this time, D r Should be less than the distance traveled by the train in the t1 period (the distance between position ① and position ③, equal to ) plus half the vehicle length (the distance between position ③ and position ④, which is 1 / 2L 车 ), that is, the following relationship is satisfied:

[0069]

[0070] For the convenience of analysis, the t1 time period is divided into two sections. In the ta time period, the train is completely covered on the previous stator section. At this time, η=1, and the current drop slope k should also satisfy equation (7). In the tb time period, the train begins to enter the next stator section. At this time, the coupling length between the train and the previous stator section is the total length of the train minus the length of the train entering the next stator section at this time, that is, N*L 车 -v*t), then there is

[0071]

[0072] Where t a is the time it takes for the train to travel from position ① to position ②, because the distance from position ① to position ② is equal to D r Subtract the distance from position ② to position ④ (half the vehicle length), so we have t a =(Dr-1 / 2L车 ) / v.

[0073] D r The length is equal to the distance the train runs in the t1 period (the train speed v multiplied by the current drop time I0 / k) plus the distance from position ③ to position ④ (the train speed v multiplied by 1 / 2t c ). Let t c =t2+t3+t4+t5, which is a fixed value. Substituting the above formula (9) into formula (4), we can calculate that the current drop slope k should satisfy:

[0074]

[0075] (ii) Train speed v before step change < v N hour

[0076] In this case, the train has entered the next stator segment before the current of the previous stator segment decreases, such as Figure 6 As shown. Figure 6 It can be seen that during the current drop process (during t1, the train runs from position ① to position ②), the train has not completely covered the previous stator segment. At this time, the coupling length between the train and the previous stator segment is the total length of the train minus the length of the train entering the next stator segment at this time. At this time, the length of the train entering the next stator segment is half of the train length minus D r , i.e. 1 / 2L 车 -Dr, then

[0077]

[0078] In this case, based on the above formula (4), the current falling slope k can be calculated to also satisfy the above formula (10).

[0079] In summary, under the condition that the train impact rate does not exceed the limit value, the current change slope k during the two-step step change process should satisfy the relationship in Table 1 below.

[0080] Table 1 The range of current change slope k during step change

[0081]

[0082] According to the above calculation results, in practical applications, for different vehicle models and operating scenarios, according to relevant vehicle parameters, linear motor parameters and operating parameters, the maximum values ​​of the two k values ​​in the above table can be calculated respectively, and then the smaller one can be taken as the basis to control the stator segment current to increase or decrease, so as to ensure that the step change time is as short as possible while meeting the ride comfort indicators.

[0083] Figure 7A flow chart of a stator segment phasing method 700 according to an aspect of the present invention is shown.

[0084] like Figure 7 As shown, the method 700 may include step 710, wherein, in response to the train reaching a step change point, a first current change rate and a second current change rate are determined.

[0085] Specifically, the first current change rate and the second current change rate can be determined based on the current speed of the train, the length of the train and the weight of a single car, the motor back-EMF coefficient of a single car on one side of the train and at unit speed, and the characteristic time constant of the stator segment step-changing control system, wherein the first current change rate is proportional to the weight of a single car, and inversely proportional to the current speed, the motor back-EMF coefficient and the characteristic time constant, and the second current change rate is proportional to the weight of a single car, and inversely proportional to the motor back-EMF coefficient.

[0086] According to a specific embodiment, the first current change rate k1 satisfies the constraint condition: The second current change rate k2 satisfies the constraint condition: Where U px is the motor back EMF coefficient, v is the current speed, t c is the characteristic time constant, m is the weight of a single carriage, L 车 is the train conductor, J max is the maximum permissible value of the impact rate of the train. Here, t c It is the time from when the traction motor control unit issues a command to disconnect the vacuum contactor of the stator switch station corresponding to the current stator segment to when the vacuum contactor of the stator switch station corresponding to the next stator segment performs a closing action and provides status feedback.

[0087] In one example, the first current change rate k1 is The maximum value of the second current change rate k2 is The maximum value of J is used to achieve the fastest step-changing speed. max Take 0.75m / s 3 .

[0088] The method 700 may include step 720 , wherein the current drop and the current increase of the stator segment during the step change process are controlled according to the smaller one of the first current change rate and the second current change rate determined above.

[0089] The smaller one of the first current change rate and the second current change rate determined in this way completes the current drop and increase as quickly as possible to complete the step change process while ensuring passenger comfort.

[0090] Although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or concurrently with other actions from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art.

[0091] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A stator segment step-changing control method for a maglev train, comprising: In response to the maglev train reaching a step-changing point, determining a first current change rate and a second current change rate based on the current speed of the maglev train, the length of the maglev train and the weight of a single carriage, the motor back-EMF coefficient of a single carriage of the maglev train on one side and at unit speed, and a characteristic time constant of a stator segment step-changing control system, wherein the first current change rate is proportional to the weight of the single carriage and inversely proportional to the current speed, the motor back-EMF coefficient and the characteristic time constant, and the second current change rate is proportional to the weight of the single carriage and inversely proportional to the motor back-EMF coefficient; and The current drop and increase of the stator segment during the step change process are controlled according to the smaller one of the first current change rate and the second current change rate.

2. The stator segment step-changing control method according to claim 1, characterized in that: The first current change rate k1 satisfies the constraint condition: The second current change rate k2 satisfies the constraint condition: Among them, U px is the motor back EMF coefficient, v is the current speed, t c is the characteristic time constant, m is the weight of the single carriage, L 车 is the length of the maglev train, J max is the maximum allowable value of the impact rate of the maglev train.

3. The stator segment step-changing control method according to claim 2, characterized in that: The first current change rate k1 is The maximum value of the second current change rate k2 is The maximum value of .

4. The stator segment step-changing control method according to claim 2, characterized in that: The J max is set to 0.

75.

5. The stator segment step-changing control method according to claim 2, characterized in that: The c It is the time from when the traction motor control unit issues a command to disconnect the vacuum contactor of the stator switch station corresponding to the current stator segment to when the vacuum contactor of the stator switch station corresponding to the next stator segment performs a closing action and provides status feedback.

6. A stator segment step-changing control system for a maglev train, comprising: A traction motor control unit is configured to: In response to the maglev train reaching a step-changing point, determining a first current change rate and a second current change rate based on the current speed of the maglev train, the length of the maglev train and the weight of a single carriage, the motor back-EMF coefficient of a single carriage of the maglev train on one side and at unit speed, and the characteristic time constant of the stator segment step-changing control system, wherein the first current change rate is proportional to the weight of the single carriage and inversely proportional to the current speed, the motor back-EMF coefficient and the characteristic time constant, and the second current change rate is proportional to the weight of the single carriage and inversely proportional to the motor back-EMF coefficient; and The current drop and increase of the stator segment during the step change process are controlled according to the smaller one of the first current change rate and the second current change rate.

7. The stator segment step-changing control system according to claim 6, characterized in that: The first current change rate k1 satisfies the constraint condition: The second current change rate k2 satisfies the constraint condition: Among them, U px is the motor back EMF coefficient, v is the current speed, t c is the characteristic time constant, m is the weight of the single carriage, L 车 is the length of the maglev train, J max is the maximum allowable value of the impact rate of the maglev train.

8. The stator segment step-changing control system according to claim 7, characterized in that: The first current change rate k1 is The maximum value of the second current change rate k2 is The maximum value of .

9. The stator segment step-changing control system according to claim 7, characterized in that: The J max is set to 0.

75.

10. The stator segment step-changing control system according to claim 7, characterized in that: The c It is the time from when the traction motor control unit issues a command to disconnect the vacuum contactor of the stator switch station corresponding to the current stator segment to when the vacuum contactor of the stator switch station corresponding to the next stator segment performs a closing action and provides status feedback.

11. A computer-readable medium having computer-executable instructions stored thereon, wherein when the computer-executable instructions are executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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