Three-step power supply system and power supply control method thereof

Abstract

The application provides a three-step power supply system and a power supply control method thereof, the system comprising three converters, a trackside switch station and a control unit; the three converters are used for three-step power supply for two sections of relatively arranged tracks; the trackside switch station comprises a plurality of switches, one end of each switch being connected with a power supply section and the other end being connected with a converter corresponding to a current power supply section; the control unit is used for controlling the conduction and disconnection of each switch of the trackside switch station, realizing the power-on and power-off of each converter to the corresponding power supply section; wherein, when a train is at a preset distance Lv from a starting point of a next power supply section, the next power supply section is powered on, and when the train is at a preset distance Lv from an ending point of a current power supply section, the current power supply section is powered off; the preset distance Lv is obtained through the following formula: Lv=Vmax*△t*G; in the formula, Vmax is a maximum speed allowed to run on a current line, △t is a maximum current rising time required by the system, and G is a weight coefficient.

Description

Technical Field

[0001] This invention relates to the field of traction power supply technology, and in particular to a three-step power supply system and its power supply control method. Background Technology

[0002] In high-speed maglev power supply systems, the converter system supplies power to the ground linear motor via trackside power supply equipment. To reduce energy consumption during long-distance power transmission, most power supply strategies employ segmented power supply methods. Commonly used methods are two-step and three-step power supply. The two-step method uses two converters to alternately supply power to the ground linear motor, such as... Figure 1 As shown, the three-step method involves three converters alternately supplying power to the ground linear motor, such as... Figure 2 As shown.

[0003] As can be seen from the power supply diagram, in the two-step power supply method, after the power supply of the current linear motor section ends, there needs to be a certain time interval before the power supply to the next section can be completed. Therefore, there will be a loss of power supply thrust at the intermediate power supply section segmentation point. Therefore, in practical applications, the three-step method is more common than the two-step method.

[0004] Currently, some literature proposes that during the three-step power supply switching process, the thrust loss when the train enters the power supply zone can be reduced by energizing the power supply in advance. However, no specific algorithm for energizing the power supply in advance is given for different power supply zones and different train operating speeds. Summary of the Invention

[0005] This invention provides a three-step power supply system and its power supply control method, which can solve the technical problem of thrust loss during power supply switching in existing power supply methods.

[0006] According to one aspect of the present invention, a three-step power supply system is provided, the system comprising three converters, a trackside switch station, and a control unit;

[0007] Three converters are used to supply power to two opposing track sections using a three-step method. The first track is divided into several power supply sections, with each section in the middle having a length of ΔL, and the lengths of the two sections at both ends being less than or equal to ΔL. The first track is cyclically powered starting from the first power supply section, using the first converter, the third converter, and the second converter. The start and end points of each power supply section in the middle of the first track correspond to the midpoints of the corresponding power supply sections on the second track. The second track is also divided into several power supply sections, with each section in the middle having a length of ΔL, and the lengths of the two sections at both ends being less than or equal to ΔL. The second track is cyclically powered starting from the first power supply section, using the second converter, the first converter, and the third converter. The start and end points of each power supply section in the middle of the second track correspond to the midpoints of the corresponding power supply sections on the first track.

[0008] The trackside switch station includes several switches, one end of each switch is connected to the power supply section, and the other end is connected to the converter corresponding to the current power supply section.

[0009] The control unit is used to control the on and off of each switch in the trackside switching station, enabling each converter to power on and off its corresponding power supply section. Specifically, when the train is a preset distance Lv from the start point of the next power supply section, the next power supply section is powered on; when the train leaves the preset distance Lv from the end point of the current power supply section, the current power supply section is powered off. The preset distance Lv is obtained using the following formula:

[0010] Lv=Vmax*△t*G

[0011] In the formula, Vmax is the maximum speed allowed to operate on the current line, Δt is the maximum current rise time required by the system, and G is the weighting coefficient.

[0012] Preferably, the starting position of each power supply section of the first track is L1 + ΔL + (nx - 2) * ΔL;

[0013] In the formula, L1 is the length of the first power supply section of the first track, and nx is the segment number of the current power supply section based on the x-th converter, where x is 1, 2 or 3.

[0014] Preferably, the starting position of each power supply segment of the second track is L2+△L+(nx-2)*△L;

[0015] In the formula, L2 is the length of the first power supply section of the second track, and nx is the segment number of the current power supply section based on the x-th converter, where x is 1, 2 or 3.

[0016] According to another aspect of the present invention, a power supply control method for a three-step power supply system is provided, the method controlling the power supply of any of the aforementioned systems, the method comprising:

[0017] Determine the train's current location;

[0018] Determine the current power supply section based on the train's current location;

[0019] When the train is at a preset distance Lv from the starting point of the next power supply section, the control unit controls the switch in the trackside switch station connected to the next power supply section to turn on, so as to enable the strain gauge to power on the next power supply section in advance.

[0020] When the train leaves the predetermined distance Lv from the end of the current power supply section, the control unit controls the switch in the trackside switch station connected to the current power supply section to disconnect, so as to delay the power supply of the current supply section by the countercurrent.

[0021] By applying the technical solution of this invention, the distance for early power-on and delayed power-off is determined based on the maximum allowable operating speed of the current line and the maximum current rise time required by the system. Furthermore, based on the control unit's control of the trackside switching station, the converter is used to achieve early power-on and delayed power-off of the corresponding power supply section, thus minimizing thrust loss during power supply switching. This invention is applicable to a three-step power supply switching control program and program architecture for different speed requirements and different linear motor power supply sections. Under different power supply section lengths and speed requirement constraints, when using this program algorithm and program architecture, the thrust loss caused by power supply switching during power supply section switching is minimized, achieving power supply switching with minimal thrust loss. Attached Figure Description

[0022] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0023] Figure 1 A schematic diagram of a two-step power supply method in the prior art is shown;

[0024] Figure 2 A schematic diagram of a three-step power supply method in the prior art is shown;

[0025] Figure 3 A schematic diagram of a three-step power supply system according to an embodiment of the present invention is shown.

[0026] Figure 4 A schematic diagram of a three-step power supply system with early power-on and delayed power-off according to an embodiment of the present invention is shown;

[0027] Figure 5 A three-step control logic flowchart according to an embodiment of the present invention is shown;

[0028] Figure 6 A flowchart illustrating the step-switching control program architecture design according to an embodiment of the present invention is shown.

[0029] Figure 7 The diagram shows the simulation test effect of the three-step power supply switching method according to an embodiment of the present invention. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0033] like Figures 3-4 As shown, the present invention provides a three-step power supply system, the system comprising three converters, a trackside switch station, and a control unit;

[0034] Three converters are used to supply power to two opposing track sections using a three-step method. The first track is divided into several power supply sections, with each section in the middle having a length of ΔL, and the lengths of the two sections at both ends being less than or equal to ΔL. The first track is cyclically powered starting from the first power supply section, using the first converter, the third converter, and the second converter. The start and end points of each power supply section in the middle of the first track correspond to the midpoints of the corresponding power supply sections on the second track. The second track is also divided into several power supply sections, with each section in the middle having a length of ΔL, and the lengths of the two sections at both ends being less than or equal to ΔL. The second track is cyclically powered starting from the first power supply section, using the second converter, the first converter, and the third converter. The start and end points of each power supply section in the middle of the second track correspond to the midpoints of the corresponding power supply sections on the first track.

[0035] The trackside switch station includes several switches, one end of each switch is connected to the power supply section, and the other end is connected to the converter corresponding to the current power supply section; wherein, the number of switches is the same as the number of power supply sections;

[0036] The control unit is used to control the on and off of each switch in the trackside switching station, enabling each converter to power on and off its corresponding power supply section. Specifically, when the train is a preset distance Lv from the start point of the next power supply section, the next power supply section is powered on; when the train leaves the preset distance Lv from the end point of the current power supply section, the current power supply section is powered off. The preset distance Lv is obtained using the following formula:

[0037] Lv=Vmax*△t*G

[0038] In the formula, Vmax is the maximum speed allowed to operate on the current line, Δt is the maximum current rise time required by the system, and G is the weighting coefficient.

[0039] This invention determines the distance for early power-on and delayed power-off based on the maximum permissible operating speed of the current line and the maximum current rise time required by the system. It then uses the control unit to control the trackside switching station to enable the converter to perform early power-on and delayed power-off for the corresponding power supply section, achieving minimal thrust loss during power supply switching. This invention is applicable to three-step power supply switching control programs and architectures for different speed requirements and different linear motor power supply sections. Under different power supply section lengths and speed constraints, when using this algorithm and architecture, it minimizes thrust loss during power supply switching, achieving power supply switching with minimal thrust loss.

[0040] According to one embodiment of the present invention, the starting position of each power supply interval of the first track is L1 + ΔL + (nx - 2) * ΔL;

[0041] In the formula, L1 is the length of the first power supply section of the first track, and nx is the segment number of the current power supply section based on the x-th converter, where x is 1, 2 or 3.

[0042] Specifically, when x = 1, n1 is the segment number of the current power supply interval based on the first converter; when x = 2, n2 is the segment number of the current power supply interval based on the second converter; and when x = 3, n3 is the segment number of the current power supply interval based on the third converter.

[0043] According to one embodiment of the present invention, the starting position of each power supply interval of the second track is L2+△L+(nx-2)*△L;

[0044] In the formula, L2 is the length of the first power supply section of the second track, and nx is the segment number of the current power supply section based on the x-th converter, where x is 1, 2 or 3.

[0045] Specifically, when x = 1, n1 is the segment number of the current power supply interval based on the first converter; when x = 2, n2 is the segment number of the current power supply interval based on the second converter; and when x = 3, n3 is the segment number of the current power supply interval based on the third converter.

[0046] The present invention also provides a power supply control method for a three-step power supply system, the method controlling the power supply of any of the above-described systems, the method comprising:

[0047] Determine the train's current location;

[0048] Determine the current power supply section based on the train's current location;

[0049] When the train is at a preset distance Lv from the starting point of the next power supply section, the control unit controls the switch in the trackside switch station connected to the next power supply section to turn on, so as to enable the strain gauge to power on the next power supply section in advance.

[0050] When the train leaves the predetermined distance Lv from the end of the current power supply section, the control unit controls the switch in the trackside switch station connected to the current power supply section to disconnect, so as to delay the power supply of the current supply section by the countercurrent.

[0051] To gain a further understanding of the present invention, the following description is provided in conjunction with... Figures 3-7 The three-step power supply system and its power supply control method of the present invention will be described in detail.

[0052] In this embodiment, in order to reduce power loss during power supply switching, a power supply switching strategy of early power-on and delayed power-off is adopted at each power supply segment switching.

[0053] like Figure 4 As shown, taking the upper track in the diagram as an example, the power supply segmentation point between converter 1 and converter 2 is position b. During the process of converter 2 switching current to converter 1, converter 1 first starts to be powered on in advance at position a. Before the segmentation point position b, the output current of converter 1 rises to the maximum given current value (I_given). After passing the segmentation point position b, converter 2 gradually reduces the current to zero. During the process of converter 1 being powered on in advance and converter 2 being powered off in a delayed manner, the train is not within this segment. Therefore, the magnitude of the force on the train is always the maximum force brought by the maximum current provided by the two tracks, realizing the power supply switching with minimum thrust loss.

[0054] The three-step switching logic is executed based on the actual current position of the train and the stator end segment position parameter information. The start / stop command and output current command value of each converter are determined according to the distance length of early power-on and delayed power-off. When a converter stops supplying power, its output current command value is set to zero.

[0055] like Figure 3As shown, in the three-step power supply strategy, the three converters form a group (right track #1 converter first segment power supply_left track #2 converter first segment power supply_right track #3 converter first segment power supply). The three converters alternately supply power to the tracks on both the left and right tracks. Therefore, the first step is to determine the switching position in the step-switching control strategy. The variables used are: △L: segment distance; L1: length of the first segment power supply section on the right track in the upward direction, supplied by converter #1; L2: length of the first segment power supply section on the left track in the upward direction, supplied by converter #2; L3: longest distance along the entire line; Lv: distance calculated based on the maximum allowable operating speed of the line for early or delayed power-on or power-off.

[0056] (1) The first section of power supply for converter #1 (the first section of section #1 on the right track). The variable n1 represents which section of power supply interval of converter #1. Here it is the first section of power supply interval of converter #1, n1 = 1. The starting position of this power supply section is 0 meters and the ending position of this section is L1 meters. Therefore, the starting position of power-on is 0 meters and the ending position of power-off is (L1 + Lv) meters.

[0057] (2) The first section of power supply for converter #2 (the first section of section #2 on the left track). The variable n2 represents which section of power supply interval of converter #2. Here it is the first section of power supply interval of converter #2, n2 = 1. The starting position of this power supply section is 0 meters and the ending position of this section is L2 meters. Therefore, the starting position of power-on is 0 meters and the ending position of power-off is (L2 + Lv) meters.

[0058] (3) The first section of power supply for converter #3 (the first section of section #3 on the right track). The variable n3 represents which section of power supply interval for converter #3. Here, it is the first section of power supply interval for converter #3, n3 = 1. The starting position of this power supply section is (L1) meters, and the ending position of this section is (L1 + n3 * △L) meters. Therefore, the starting position of power-on is (segment starting position - Lv) meters, and the ending position of power-off is (segment ending position + Lv) meters.

[0059] (4) The second section of power supply for converter #1 (left track), variable n1 represents which power supply section of converter #1. Here it is the second power supply section of converter #1, n1 = 2. The starting position of this power supply section is (L2 + (n1 - 2) * △L) meters, and the ending position of this section is (L2 + (n1 - 1) * △L) meters. Therefore, the starting position of power-on is (starting position of section - Lv) meters, and the ending position of power-off is (ending position of section + Lv) meters.

[0060] (5) The second section of power supply for converter #2 (right track), variable n2 represents which power supply section of converter #2. Here it is the second power supply section of converter #2, n2 = 2. The starting position of this power supply section is (L1 + △L + (n2 - 2) * △L) meters, and the ending position of this section is (L1 + △L + (n2 - 1) * △L) meters. Therefore, the starting position of power-on is (segment starting position - Lv) meters, and the ending position of power-off is (segment ending position + Lv) meters.

[0061] (6) The second section of power supply for converter #3 (left track), variable n3 represents which power supply section of converter #3. Here it is the second power supply section of converter #3, n3 = 2. The starting position of this power supply section is (L2 + △L + (n3 - 2) * △L) meters, and the ending position of this section is (L2 + △L + (n3 - 1) * △L) meters. Therefore, the starting position of power-on is (segment starting position - Lv) meters, and the ending position of power-off is (segment ending position + Lv) meters.

[0062] (7) The above six points explain the determination of the power-on and power-off positions of the converter in different power supply segments. (1) to (3) respectively indicate the position determination of the first power supply segment of converter 1#-2#-3#, with the power supply segments located on the right track-left track-right track respectively; (4) to (6) respectively indicate the position determination of the second power supply segment of converter 1#-2#-3#, with the power supply segments located on the left track-right track-left track respectively; when the power supply segment is located on the left track, the starting position of the power supply segment is (L2+△L+(nx-2)*△L) meters. The end position of a segment is (L2+△L+(nx-1)*△L) meters, then the power-on start position is (segment start position-Lv) meters, and the power-off end position is (segment end position+Lv) meters; when the power supply segment is located on the right track, the segment start position of this power supply segment is (L1+△L+(nx-2)*△L) meters, the segment end position is (L1+△L+(nx-1)*△L) meters, then the power-on start position is (segment start position-Lv) meters, and the power-off end position is (segment end position+Lv) meters; where nx represents the nth power supply segment of converter x.

[0063] (8) Following the pattern of (4) to (6), and in accordance with the pattern of alternating distribution of the power supply segments on the right track, left track, right track, etc., the starting position and ending position of the power supply segment are determined, thereby obtaining the starting position of power-on and the ending position of power-off.

[0064] (9) Due to the uncertainty of the line length, first ensure that the power supply segment in the middle part of the left and right tracks has a fixed power supply length △L meters. The lengths of the power supply segments at both ends, except for the middle segment, may not be consistent with △L, similar to the power-on and power-off position determination of the first power supply section of converter #1 and the first power supply section of converter #2 described in (1) and (2) respectively. Here, as Figure 4 The power supply segment layout diagram shown assumes that the last power supply section corresponding to converters #1 and #2 is △L meters long, while the length of the power supply section corresponding to converter #3 is not the same as △L meters. Therefore, according to the rule summarized in section (8), the upper and lower power supply positions of the last power supply segments of the left and right tracks are solved respectively. Based on the power supply allocation of three converters as a group, assuming the last two power supply sections are the xth power supply sections of converters #2 and #3, then n2 = n3 = x. The power supply section of converter #2 is located on the right track, so the starting position of this power supply section is (L1 + △L + (n2 - 2) * △L) meters, and the ending position of this section is (L1 + △L + (n2 - 1) * △L) meters. Therefore, the starting position for power-on is (segment starting position - Lv) meters, and the ending position for power-off is (segment ending position + Lv) meters. The power supply section of converter #3 is located on the left track, so the starting position of this power supply section is (L2 + △L + (nx - 2) * △L) meters, and the ending position of this section is (L3) meters. Therefore, the starting position for power-on is (segment starting position - Lv) meters, and the ending position for power-off is (segment ending position + Lv) meters.

[0065] The above completes the determination of the step-change position and power-on / off position of all power supply sections along the entire line.

[0066] Lv: The distance for early power-on or delayed power-off, calculated based on the maximum permissible operating speed of the line. The specific calculation formula is shown below:

[0067] Lv = Vmax * Δt * G, where Vmax is the maximum speed allowed for the line to operate at, in m / s; Δt is the maximum current rise time required by the system, usually in milliseconds; and G is the weighting coefficient, typically 1.5.

[0068] When a train leaves a section, if the distance the train has traveled (the distance the locomotive has traveled from the section point) is greater than (1.5*Ltrain) meters after the section point, the current needs to be unloaded to within a certain current value Idel_max, where Ltrain is the train length, which is generally (1.5*Ltrain). <Lv。

[0069] like Figure 5As shown, it is a three-step control logic flow chart. (1) First, judge that different converters correspond to different power supply intervals. After determining the power supply interval corresponding to the converter, within the power supply interval, first judge whether the converter starts to work; (2) When the head of the train is less than Lv meters away from the starting position of the section, or when the head of the train is less than Lv meters away from the ending position of the section, the associated switch station corresponding to the current converter closes, and the working state of the converter is maintained, and at the same time, a given current value is output; (3) In the delayed power-off stage, when the running distance of the train (the distance of the head of the train from the section point) is greater than (1.5*Ltrain) meters after the position of the section point, the output current command value is within Idel_max.

[0070] Next, the three-step control program architecture design is carried out.

[0071] According to the three-step control logic design flow chart, the step-changing control program design is carried out. Similarly, for Figure 3 the three-step power supply line schematic diagram shown, from Figure 3 it can be seen that the lengths of the middle power supply sections are all △L, and there are power supply sections with different lengths at both ends of the line. The step-changing control modules Transform_cnv01, Transform_cnv02, and Transform_cnv03 for the power supply sections with equal length △L of the 1#, 2#, and 3# converters are established respectively; at the same time, the step-changing control modules Transform_cnv01_01, Transform_cnv02_01, and Transform_cnv03_01 for the power supply sections with different lengths of the 1#, 2#, and 3# converters are established; a total of six different modules are established, corresponding to the power supply sections with length △L and the power supply sections with length not △L of the three converters.

[0072] According to the position range of the train operation, different program modules are sequentially invoked for step-changing control. The design process of the three-step power supply controller program architecture is as Figure 6 shown.

[0073] In Figure 6 it, the design and application of six different functions are elaborated in detail:

[0074] (1) For the power supply sections with different lengths of the 1# converter, when the current position s(t) of the train operation < L1, the program module Transform_cnv01_01 is called, and according to Figure 3 the description of the distance range between the corresponding power-on starting position and the power-off ending position, the step-changing control design is carried out according to the Figure 5 control logic flow chart in it.

[0075] (2) For different lengths of power supply sections of the 2# converter, when the current position of the train s(t) < L2, call the Transform_cnv02_01 program module. According to Figure 3 the description of the distance range between the corresponding power-on start position and the power-off end position, perform the step-changing control design according to the Figure 5 control logic flowchart in it;

[0076] (3) For different lengths of power supply sections of the 3# converter, when the current position of the train s(t) < L3, call the Transform_cnv03_01 program module. According to Figure 3 the description of the distance range between the corresponding power-on start position and the power-off end position, perform the step-changing control design according to the Figure 5 control logic flowchart in it;

[0077] (4) For the power supply sections of the 1# converter with the same length △L, call the Transform_cnv01 program module. As can be seen from the schematic diagram of the three-step power supply line layout Figure 3 , the distance difference between the start positions of the power supply sections with the same length is (1.5 * △L) meters. ① First, calculate the relative distance s0(t) between the current train position after subtracting L2 and the start position of the first power supply section powered by the 1# converter, using the current position of the train s(t) - L2 = s0(t); ② Divide the relative distance s0(t) by (1.5 * △L) and take the integer K, then K is the number of segments of the current equal-length power supply section corresponding to the 1# converter; ③ Then subtract K integer multiples of (1.5 * △L) meters from the calculated relative distance s0(t) to obtain the current position of the train within the current power supply section; ④ According to the distance range between the power-on start position and the power-off end position, perform the step-changing control design according to the Figure 5 control logic flowchart in it;

[0078] (5) For the power supply sections of the 2# converter with the same length △L, call the Transform_cnv02 program module. From the schematic diagram of the three-step power supply line layout Figure 3It can be seen that the distance difference between the starting positions of power supply sections of the same length is (1.5*△L) meters. ① First, calculate the relative distance s0(t) between the current train position after subtracting (L1+△L) and the starting position of the first power supply section powered by converter #2. The current position of the train is s(t) - (L1+△L) = s0(t); ② Divide the relative distance s0(t) by (1.5*△L) and round down to K. K is the number of sections of the current equal-length power supply zone corresponding to converter #2; ③ Subtract (1.5*△L) meters, which is an integer multiple of K, from the calculated relative distance s0(t) to obtain the current position of the train within the current power supply zone; ④ According to the distance range between the power-on start position and the power-off end position in Table 1, according to... Figure 5 The control logic flowchart in the diagram is used to design step-change control.

[0079] (6) For the same length △L power supply section of converter #3, call the Transform_cnv03 program module to obtain the power supply line layout diagram of the three-step method. Figure 3 It can be seen that the distance difference between the starting positions of power supply sections of the same length is (1.5*△L) meters. ① First, calculate the relative distance s0(t) between the current train position (excluding L1) and the starting position of the first power supply section powered by converter #3. Use the current position of the train s(t) - L1 = s0(t); ② Divide the relative distance s0(t) by (1.5*△L) and round down to K. K is the number of sections in the current equal-length power supply zone corresponding to converter #1; ③ Subtract (1.5*△L) meters, an integer multiple of K, from the calculated relative distance s0(t) to obtain the current position of the train within the current power supply zone; ④ According to the distance range between the power-on start position and the power-off end position in Table 1, according to... Figure 5 The control logic flowchart in the diagram is used to design the step-change control.

[0080] Therefore, according to Figure 6 The program architecture design flowchart can realize three-step step-by-step power supply control on lines with different segment power supply lengths and different operating speed requirements according to different location requirements, and minimize the thrust loss caused by step-by-step power supply.

[0081] Simulation tests were conducted using the three-step power supply control algorithm and program architecture proposed in this invention. The test results are as follows: Figure 7 As shown. By Figure 7As can be seen, after converter #1 is energized at position a, it reaches its maximum current output before the power supply switching point at position b, ensuring stable power supply from converter #1 once the train enters its power supply area (the area after position b). Simultaneously, after the train fully enters converter #1's power supply area, converter #2 is energized later, preventing thrust loss due to the current drop in converter #2 during the transition from position b to position c. Therefore, the three-step power supply control logic and program proposed in this paper are effective and feasible, minimizing thrust loss during the three-step power supply switching process.

[0082] In summary, this invention provides a three-step power supply system and its power supply control method. Based on the train's operating speed, the segmentation of linear motor power supply, and the buffer time for power-on and power-off, the controller program architecture and control algorithm are designed. This system can be used as an independent module for position identification and application, ensuring the matching of the train's operating position with the operation of different power supply zones, and achieving minimum thrust loss during power supply switching. This invention is applicable to different operating speeds and different power supply zone scenarios, achieving minimum thrust loss during power supply switching.

[0083] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0084] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0085] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0086] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A three-step power supply system, characterized in that, The system includes three converters, a trackside switch station, and a control unit; Three converters are used to supply power to two opposing track sections using a three-step method. The first track is divided into several power supply sections, with each section in the middle having a length of ΔL, and the lengths of the two sections at both ends being less than or equal to ΔL. The first track is cyclically powered starting from the first power supply section, using the first converter, the third converter, and the second converter. The start and end points of each power supply section in the middle of the first track correspond to the midpoints of the corresponding power supply sections on the second track. The second track is also divided into several power supply sections, with each section in the middle having a length of ΔL, and the lengths of the two sections at both ends being less than or equal to ΔL. The second track is cyclically powered starting from the first power supply section, using the second converter, the first converter, and the third converter. The start and end points of each power supply section in the middle of the second track correspond to the midpoints of the corresponding power supply sections on the first track. The trackside switch station includes several switches, one end of each switch is connected to the power supply section, and the other end is connected to the converter corresponding to the current power supply section. The control unit is used to control the on and off of each switch in the trackside switching station, enabling each converter to power on and off its corresponding power supply section. Specifically, when the train is a preset distance Lv from the start point of the next power supply section, the next power supply section is powered on; when the train leaves the preset distance Lv from the end point of the current power supply section, the current power supply section is powered off. The preset distance Lv is obtained using the following formula: Lv=Vmax*△t*G In the formula, Vmax is the maximum speed allowed to operate on the current line, Δt is the maximum current rise time required by the system, and G is the weighting coefficient.

2. The system according to claim 1, characterized in that, The starting position of each power supply section of the first track is L1 + △L + (nx - 2) * △L; In the formula, L1 is the length of the first power supply section of the first track, and nx is the segment number of the current power supply section based on the x-th converter, where x is 1, 2 or 3.

3. The system according to claim 1, characterized in that, The starting position of each power supply section of the second track is L2+△L+(nx-2)*△L; In the formula, L2 is the length of the first power supply section of the second track, and nx is the segment number of the current power supply section based on the x-th converter, where x is 1, 2 or 3.

4. A power supply control method for a three-step power supply system, characterized in that, The method provides power supply control for the system according to any one of claims 1-3, the method comprising: Determine the train's current location; Determine the current power supply section based on the train's current location; When the train is at a preset distance Lv from the starting point of the next power supply section, the control unit controls the switch in the trackside switch station connected to the next power supply section to turn on, so as to enable the strain gauge to power on the next power supply section in advance. When the train leaves the predetermined distance Lv from the end of the current power supply section, the control unit controls the switch in the trackside switch station connected to the current power supply section to disconnect, so as to delay the power supply of the current supply section by the countercurrent.

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