Pantograph contact force switching control circuit and method, and railway train

Abstract

This invention relates to the field of rail train technology, providing a pantograph contact force switching control circuit and method, and a rail train. The circuit includes: a contact network power supply system identification circuit, which identifies the current contact network power supply system and outputs the identification result; the power supply system includes at least DC power supply and AC power supply; a switching control circuit, which outputs a switching command based on the power supply system identification result; a control terminal of an air circuit switching valve group electrically connected to the switching control circuit, which switches to a first or second working position according to the switching command; and first and second pressure setting valve groups, the input terminal of the first pressure setting valve group being connected to the first working position and outputting a first preset contact force required for DC power supply; the input terminal of the second pressure setting valve group being connected to the second working position and outputting a second preset contact force required for AC power supply, both output terminals being connected to the pantograph lifting airbag. This invention achieves dynamic adaptation of contact force when the train is running on a DC / AC hybrid line.

Description

Technical Field

[0001] This invention relates to the field of rail train technology, and in particular to a pantograph contact force switching control circuit and method, and a rail train. Background Technology

[0002] With the rapid development of railways, the simultaneous operation of DC and AC power supplies on the same line is becoming increasingly common, especially in cross-line operation scenarios such as urban and intercity railways. DC and AC power supplies differ significantly in electrical characteristics, vertical stiffness, and suspension methods, thus imposing different requirements on the pantograph-catenary contact force under different power supply systems: DC power supply sections require a larger contact force to ensure pantograph-catenary following and control the rate of line-off; AC power supply sections require a relatively smaller contact force to reduce pantograph-catenary wear and avoid fatigue damage to the contact wire.

[0003] In existing technologies, the pantograph lifting air chamber pressure is usually preset to a relatively fixed value when the train leaves the factory, and cannot be dynamically adjusted online according to the contact network power supply system of the operating section. When the train moves from an AC power supply section to a DC power supply section, or from a DC power supply section to an AC power supply section, the fixed pantograph-catenary contact force cannot simultaneously meet the optimal matching requirements of the two contact networks, which can easily lead to problems such as increased pantograph-catenary wear, increased disconnection rate, and frequent arcing events. Summary of the Invention

[0004] This invention provides a pantograph contact force switching control circuit and method, and a rail train, which realizes a contact force switching scheme with fast response, reliable control and simple structure, thereby realizing dynamic adaptation of contact force when the train is running on AC / DC hybrid power supply lines.

[0005] In a first aspect, the present invention provides a pantograph contact force switching control circuit, comprising: A power supply system identification circuit for overhead contact lines is used to identify the current power supply system of the overhead contact lines and output the power supply system identification result; wherein, the power supply system includes at least DC power supply and AC power supply; A switching control circuit is electrically connected to the contact network power supply system identification circuit and is used to output a switching command based on the power supply system identification result. A gas path switching valve assembly has a first working position and a second working position. The control terminal of the gas path switching valve assembly is electrically connected to the switching control circuit and is used to switch to the first working position or the second working position according to the switching command. A first pressure setting valve group and a second pressure setting valve group, wherein the input end of the first pressure setting valve group is connected to the first working position and is used to output the first preset contact force required for the DC power supply; the input end of the second pressure setting valve group is connected to the second working position and is used to output the second preset contact force required for the AC power supply; the output ends of the first pressure setting valve group and the second pressure setting valve group are both connected to the pantograph lifting airbag.

[0006] In some embodiments, the contact network power supply system identification circuit includes: The main identification sub-circuit is an electronic voltage transformer, used to acquire the mains voltage signal in real time and output the first power supply system identification result; The backup identification sub-circuit is used to independently identify the current power supply system of the overhead contact line and output the identification result of the second power supply system. A priority selection circuit is electrically connected to the main identification sub-circuit and the backup identification sub-circuit, respectively, and is used to use the first power supply system identification result as the final power supply system identification result when the output of the main identification sub-circuit is determined to be valid, and to use the second power supply system identification result as the final power supply system identification result when the output of the main identification sub-circuit is confirmed to be invalid.

[0007] In some embodiments, the pneumatic switching valve assembly is a two-position five-way solenoid valve; or... The pneumatic switching valve assembly includes a first two-position five-way solenoid valve and a second two-position five-way solenoid valve connected in series. The control coils of both valves are electrically connected to the switching control circuit. When both valves are switched to the same operating position, the corresponding pneumatic path is opened; or... The gas path switching valve group includes a first two-position five-way solenoid valve and a second two-position five-way solenoid valve connected in parallel. The control coils of the first two-position five-way solenoid valve and the second two-position five-way solenoid valve are electrically connected to the switching control circuit. The gas outlets of the first two-position five-way solenoid valve and the second two-position five-way solenoid valve are connected to the first pressure setting valve group and the second pressure setting valve group after being merged by a shuttle valve.

[0008] In some embodiments, it also includes: The pantograph holding interlock circuit includes a pantograph relay, the normally open contact of which is connected in series with the front end of the control terminal of the air circuit switching valve group, for allowing contact force switching control when the pantograph is raised and held. The pantograph solenoid valve is located at the front end of the air circuit of the air circuit switching valve group for controlling the opening and closing of the pantograph air circuit. The switching control circuit is a switching relay, whose coil is electrically connected to the contact network power supply system identification circuit. The normally open contact of the switching relay is connected in series with the first working position control coil of the gas path switching valve group, and the normally closed contact is connected in series with the second working position control coil of the gas path switching valve group.

[0009] In some embodiments, it also includes: A collaborative control signal output interface is electrically connected to the overhead contact line power supply system identification circuit, and is used to output the power supply system identification result to the train traction converter and the train braking system. The train traction converter is used to switch control parameters according to the power supply system identification result, and the train braking system is used to adjust the maximum electric braking force limit according to the power supply system identification result.

[0010] In some embodiments, it also includes: A time-delay holding circuit, electrically connected to both the overhead contact line power supply system identification circuit and the switching control circuit, is used to maintain the state of the switching control circuit for a preset duration when the mains voltage signal disappears; and / or, The grid voltage pre-identification circuit is electrically connected to the contact network power supply system identification circuit and the switching control circuit, respectively. It is used to predict the power supply system based on the establishment characteristics of the grid voltage signal during the pantograph raising process, and output the prediction result to the switching control circuit before the pantograph is fully raised, so that the air circuit switching valve group can switch to the corresponding working position in advance.

[0011] In some embodiments, it also includes: A contact wire type identification circuit is used to identify the type of the current contact wire and output the type identification result; wherein, the type includes at least rigid contact wire and flexible contact wire; The preset value determination unit is electrically connected to the overhead contact line power supply system identification circuit and the overhead contact line type identification circuit, respectively, and is used to determine the corresponding preset contact force as the first preset contact force or the second preset contact force based on at least one of the current overhead contact line power supply system, the current overhead contact line type, and the current train running speed.

[0012] In some embodiments, it also includes: An acceleration detection circuit, electrically connected to the switching control circuit, is used to predict the power supply restoration time based on the coasting time when the train enters the coasting state from the traction state according to the change in the train's acceleration, and to output a pre-trigger signal to the switching control circuit within a preset time before the power supply is restored.

[0013] In a second aspect, the present invention also provides a pantograph contact force switching control method, executed by the pantograph contact force switching control circuit described in the first aspect, comprising: Obtain the power supply system identification result output by the overhead contact system power supply system identification circuit; wherein, the power supply system identification result indicates whether the current overhead contact system is powered by DC or AC. When the power supply system identification result is DC power supply, the air path switching valve group is controlled to switch to the first working position, so that the air path supplies air to the pantograph lifting airbag through the first pressure setting valve group, and the first preset contact force is set in an open-loop manner. When the power supply system identification result is AC power supply, the air path switching valve group is controlled to switch to the second working position, so that the air path supplies air to the pantograph lifting airbag through the second pressure setting valve group, and the second preset contact force is set in an open-loop manner.

[0014] Thirdly, the present invention also provides a rail train, including the pantograph contact force switching control circuit as described in the first aspect.

[0015] This invention abandons the complex traditional scheme of real-time monitoring of contact force and closed-loop feedback adjustment. It only requires identifying the power supply system of the overhead contact system and directly controlling the air circuit switching valve group to select the corresponding pressure setting valve group via hard-wired circuitry. This eliminates the need for continuous monitoring and iterative adjustment of the contact force, resulting in extremely fast switching response and eliminating the oscillation or overshoot problems associated with closed-loop control. Furthermore, the entire switching control circuit is composed of hardware components and their electrical connections, without relying on software algorithms or complex sensor networks, thus exhibiting higher anti-interference capabilities and operational reliability in the strong electromagnetic interference environment of rail transit. In addition, for example, to meet the needs of mixed DC and AC power supply operation in suburban urban railways, two independent pressure setting valve groups output different preset contact forces, enabling online dynamic switching of the train pantograph-catenary contact force according to the power supply system of the operating section. This ensures reliable matching between the pantograph and the catenary, reliable current collection under different power supply systems, and minimizes pantograph-catenary wear. It also ensures pantograph-catenary following performance in different power supply sections, extending the service life of the pantograph contactor and the overhead contact system, and reducing the rate of disconnection and the risk of arcing. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1This is a schematic diagram of the circuit principle of a pantograph contact force switching control circuit provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the air circuit principle corresponding to a pantograph contact force switching control circuit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the circuit principle corresponding to the contact network power supply system identification circuit in a pantograph contact force switching control circuit provided in an embodiment of the present invention; Figure 4 This is a flowchart illustrating a pantograph contact force switching control method provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0019] Figure 1 This is a schematic diagram of the circuit principle of a pantograph contact force switching control circuit provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the pneumatic circuit principle corresponding to a pantograph contact force switching control circuit provided in an embodiment of the present invention. Combined with... Figure 1 and Figure 2 A pantograph contact force switching control circuit includes a contact network power supply system identification circuit, a switching control circuit GVSR, a pneumatic switching valve group U02, a first pressure setting valve group U041, and a second pressure setting valve group U042. The contact network power supply system identification circuit is used to identify the current contact network power supply system and output the power supply system identification result; wherein, the power supply system includes at least DC power supply and AC power supply; the switching control circuit GVSR is electrically connected to the contact network power supply system identification circuit and is used to output a switching command according to the power supply system identification result; the pneumatic switching valve group U042 has a first pressure setting valve group U041 and a second pressure setting valve group U042. The first and second working positions are respectively connected. The control terminal of the air path switching valve group U02 is electrically connected to the switching control circuit GVSR, and is used to switch to the first or second working position according to the switching command. The input terminal of the first pressure setting valve group U041 is connected to the first working position and is used to output the first preset contact force required for DC power supply. The input terminal of the second pressure setting valve group U042 is connected to the second working position and is used to output the second preset contact force required for AC power supply. The output terminals of the first pressure setting valve group U041 and the second pressure setting valve group U042 are both connected to the pantograph lifting airbag.

[0020] Specifically, the pantograph contact force switching control circuit refers to the hardware circuit used to control the contact pressure between the pantograph and the overhead contact line of a railcar. It consists of multiple electronic components, relays, solenoid valves, pneumatic components, and their connections. It can change the air pressure output to the pantograph lifting airbag according to different overhead contact line power supply systems, thereby changing the contact force. The overhead contact line power supply system identification circuit refers to the hardware circuit module used to detect and determine whether the current overhead contact line is powered by DC or AC. Its output terminal outputs an electrical signal representing the determination result, i.e., the power supply system identification result. The power supply system refers to the type of electrical energy provided by the overhead contact line, which includes at least DC and AC power supply. DC power supply voltage is DC1500V or DC3000V, and AC power supply voltage is AC25kV or AC15kV.

[0021] The power supply system identification result refers to the electrical signal output by the contact network power supply system identification circuit. This signal can distinguish whether the current contact network is powered by DC or AC; for example, a high level indicates DC power supply, and a low level indicates AC power supply. The switching control circuit GVSR refers to the hardware circuit that receives the power supply system identification result and outputs a switching command based on that result. Its output terminal is connected to the control terminal of the pneumatic switching valve group U02. The switching command refers to the electrical signal output by the switching control circuit GVSR used to drive the pneumatic switching valve group U02.

[0022] The air path switching valve assembly U02 refers to a valve assembly used to change the flow path of compressed air. It has two different working positions: a first working position and a second working position, corresponding to DC power supply mode and AC power supply mode, respectively. The first working position refers to the working position of the air path switching valve assembly U02 in DC power supply mode. In this position, compressed air flows to the lifting air bladder via the first pressure setting valve assembly U041. The second working position refers to the working position of the air path switching valve assembly U02 in AC power supply mode. In this position, compressed air flows to the lifting air bladder via the second pressure setting valve assembly U042. The first pressure setting valve assembly U041 refers to a pneumatic component assembly used to adjust the compressed air pressure to the first preset contact force required for DC power supply, such as a first pressure regulating valve. The second pressure setting valve assembly U042 refers to a pneumatic component assembly used to adjust the compressed air pressure to the second preset contact force required for AC power supply, such as a second pressure regulating valve. The first preset contact force refers to a target contact force value preset for DC power supply, such as a specific value within the range of 70N to 140N, like 120N. The second preset contact force refers to a target contact force value preset for AC power supply, such as a specific value within the range of 60N to 90N, like 80N. The pantograph lifting airbag refers to the airbag-type actuator in the pantograph lifting mechanism, which can adjust the static lifting force of the pantograph on the contact wire by changing its internal air pressure, thereby changing the pantograph-contact wire contact force.

[0023] First, the overhead contact line power supply system identification circuit continuously detects the power supply system of the current train section. This circuit uses internal hardware logic to determine whether the current overhead contact line is powered by DC or AC, and outputs the result as an electrical signal. This power supply system identification result can be a high or low level signal; for example, a high level represents DC power supply, and a low level represents AC power supply. Then, the switching control circuit GVSR is electrically connected to the overhead contact line power supply system identification circuit and receives the identification result. Based on the received signal, the switching control circuit GVSR generates a corresponding switching command. For example, when it receives a high level representing DC power supply, the switching control circuit GVSR outputs a command to switch the pneumatic switching valve group U02 to the first operating position; when it receives a low level representing AC power supply, it outputs a command to switch the pneumatic switching valve group U02 to the second operating position.

[0024] The control terminal of the air path switching valve assembly U02 is electrically connected to the switching control circuit GVSR. Upon receiving a switching command, its internal valve core actuates, placing the air path switching valve assembly U02 in either the first or second operating position. Specifically, when the switching command requires DC power supply mode, the air path switching valve assembly U02 switches to the first operating position, at which time the input terminal of the first pressure setting valve assembly U041 is connected to the air source; when the switching command requires AC power supply mode, the air path switching valve assembly U02 switches to the second operating position, at which time the input terminal of the second pressure setting valve assembly U042 is connected to the air source. The input terminal of the first pressure setting valve assembly U041 is connected to the first operating position, and it has an internal pressure reducing mechanism, such as a pressure regulating spring and a diaphragm. When compressed air enters the first pressure setting valve assembly U041 from the first operating position, the first pressure setting valve assembly U041 reduces the input pressure and stabilizes it at the air pressure value corresponding to the first preset contact force, and then outputs it from its output terminal. Similarly, the input end of the second pressure setting valve group U042 is connected to the second working position. When compressed air enters, the second pressure setting valve group U042 reduces the pressure and outputs it after stabilizing the air pressure value corresponding to the second preset contact force.

[0025] The outputs of both the first pressure setting valve group U041 and the second pressure setting valve group U042 are connected to the pantograph lifting airbag. Therefore, when the train is in a DC power supply section, the lifting airbag receives the air pressure corresponding to the first preset contact force, and the pantograph presses against the contact wire with a larger first preset contact force to ensure good following performance; when the train is in an AC power supply section, the lifting airbag receives the air pressure corresponding to the second preset contact force, and the pantograph presses against the contact wire with a smaller second preset contact force to reduce pantograph-contact wire wear.

[0026] Therefore, this invention abandons the complex traditional scheme of real-time monitoring of contact force and closed-loop feedback adjustment. It only requires identifying the power supply system of the overhead contact system and directly controlling the air circuit switching valve group U02 to select the corresponding pressure setting valve group via a hard-wired circuit. This eliminates the need for continuous monitoring and iterative adjustment of the contact force, resulting in extremely fast switching response and eliminating the oscillation or overshoot problems associated with closed-loop control. Furthermore, the entire switching control circuit is composed of hardware components and their electrical connections, without relying on software algorithms or complex sensor networks, thus exhibiting higher anti-interference capabilities and operational reliability in the strong electromagnetic interference environment of rail transit. Additionally, for example, to meet the needs of mixed DC and AC power supply operation in suburban urban railways, two independent pressure setting valve groups output different preset contact forces, enabling online dynamic switching of the train pantograph-catenary contact force according to the power supply system of the operating section. This ensures reliable matching between the pantograph and the catenary, reliable current collection under different power supply systems, and minimizes pantograph-catenary wear. It also ensures pantograph-catenary following performance in different power supply sections, extending the service life of the pantograph contactor and the overhead contact system, and reducing the rate of disconnection and the risk of arcing.

[0027] In some embodiments, the overhead contact line power supply system identification circuit includes: a main identification sub-circuit, which is an electronic voltage transformer, used to acquire the grid voltage signal in real time and output a first power supply system identification result; a backup identification sub-circuit, used to independently identify the current power supply system of the overhead contact line and output a second power supply system identification result; and a priority selection circuit, which is electrically connected to the main identification sub-circuit and the backup identification sub-circuit respectively, used to take the first power supply system identification result as the final power supply system identification result when the output of the main identification sub-circuit is determined to be valid, and to take the second power supply system identification result as the final power supply system identification result when the output of the main identification sub-circuit is confirmed to be invalid.

[0028] Specifically, the main identification sub-circuit refers to the sub-circuit that undertakes the primary identification task in the contact network power supply system identification circuit. Its identification result has the highest priority. The main identification sub-circuit is specifically an electronic voltage transformer. An electronic voltage transformer is a measuring device that uses electronic technology to acquire, transform, and output voltage signals. It has a built-in electrical control box that can automatically determine the power supply system based on the acquired grid voltage signal and output the corresponding level signal. The grid voltage signal refers to the voltage signal obtained by the pantograph from the contact network, including the instantaneous value of DC or AC voltage. The first power supply system identification result refers to the identification result output by the main identification sub-circuit, i.e., the electronic voltage transformer. The backup identification sub-circuit refers to the sub-circuit used to take over the identification task when the main identification sub-circuit fails or its output is invalid. Its identification result is the second power supply system identification result. The second power supply system identification result refers to the identification result output by the backup identification sub-circuit. The priority selection circuit refers to the hardware circuit used to determine whether the output of the main identification sub-circuit is valid and, based on the determination result, select whether to use the main identification result or the backup identification result.

[0029] The overhead contact line power supply system identification circuit internally includes a main identification sub-circuit, a backup identification sub-circuit, and a priority selection circuit. The main identification sub-circuit is an electronic voltage transformer. When the pantograph is raised, the electronic voltage transformer collects the grid voltage signal in real time. Its built-in electrical control box analyzes the form of the grid voltage signal: if DC voltage is detected, it is determined to be DC power supply, and a high level is output as the first power supply system identification result; if AC voltage is detected, it is determined to be AC ​​power supply, and a low level is output as the first power supply system identification result. The backup identification sub-circuit operates independently of the main identification sub-circuit, using a different principle to identify the power supply system and outputting a second power supply system identification result.

[0030] The priority selection circuit is electrically connected to both the main identification sub-circuit and the backup identification sub-circuit. This circuit first determines whether the output of the main identification sub-circuit is valid. Validity criteria can include whether the output level of the electronic voltage transformer is within a reasonable range, or whether there is a continuous signal output. When the output of the main identification sub-circuit is determined to be valid, for example, if the electronic voltage transformer is normally outputting a high or low level, the priority selection circuit uses the first power supply system identification result as the final power supply system identification result and outputs it to the switching control circuit. When the output of the main identification sub-circuit is determined to be invalid, for example, due to a fault in the electronic voltage transformer, signal loss, or abnormal output, the priority selection circuit automatically switches, using the second power supply system identification result as the final power supply system identification result.

[0031] Therefore, this embodiment of the invention establishes a redundant architecture with primary identification as the priority and backup identification as a fallback. Electronic voltage transformers directly measure the grid voltage signal, which is the most direct and accurate identification method, and thus is set as the highest priority. The backup identification sub-circuit takes over when the primary identification fails, ensuring uninterrupted identification functionality. Automatic hardware-level switching is achieved through a priority selection circuit, requiring no software intervention. This results in fast switching speeds, high reliability, and avoids the delays and failure risks associated with software judgment.

[0032] In some embodiments, the backup identification sub-circuit includes at least one of the following: a ground beacon identification sub-circuit for identifying the current power supply mode of the overhead contact system based on ground kilometer beacon signals or transponder signals; and a soft measurement identification sub-circuit for identifying the current power supply mode of the overhead contact system based on the harmonic characteristics of the electrical signals of the traction converter.

[0033] Specifically, the ground beacon identification subcircuit refers to a subcircuit that uses fixed location markers on the ground, such as kilometer markers and transponders, to identify the contact network power supply system. This subcircuit receives ground beacon signals and, based on a pre-stored track map, determines whether the section corresponding to each kilometer marker or transponder is powered by DC or AC to determine the current contact network power supply system. Ground kilometer marker signals refer to mileage markers or corresponding electronic signals placed beside the track, used to indicate the train's current kilometer position. Transponder signals refer to the radio beacon signals sent to the train by transponders placed in the middle of the track, which may contain information such as track parameters and temporary speed limits. For the ground beacon identification subcircuit, a track database is pre-stored, recording the contact network power supply system of the section corresponding to each kilometer marker or transponder. When a train passes a ground kilometer marker or transponder, the subcircuit receives the corresponding signal, queries the database based on the location information in the signal, determines whether the current location belongs to a DC or AC power supply section, and outputs the corresponding power supply system identification result.

[0034] The soft-sensor identification subcircuit is connected to the current or voltage sampling points of the traction converter to acquire the current or voltage waveforms on the converter input side in real time. When powered by DC, the converter input side exhibits a DC voltage superimposed with a small amount of ripple, with harmonic components concentrated at specific harmonic frequencies. When powered by AC, the input side is powered by industrial frequency AC, and the harmonic components include the fundamental frequency and its odd harmonics. The soft-sensor identification subcircuit performs a Fast Fourier Transform on the acquired electrical signal to extract the energy or peak characteristics of a specific frequency band. This is compared with pre-stored harmonic fingerprints for DC and AC power supplies to determine the current power supply mode and output the corresponding identification result.

[0035] Therefore, the ground beacon identification sub-circuit of this invention utilizes existing railway signaling infrastructure, providing accurate identification unaffected by weather and lighting conditions, making it a highly reliable backup identification method. The soft-measurement identification sub-circuit utilizes the inherent electrical signals of the traction converter, eliminating the need for additional hardware sensors and achieving low-cost power supply system identification. It also provides a completely heterogeneous redundant verification source for the identification system. The two backup identification sub-circuits can be used complementaryly, further improving the robustness and applicability of the identification system.

[0036] Figure 3 This is a schematic diagram of the circuit principle corresponding to the contact network power supply system identification circuit in a pantograph contact force switching control circuit provided in an embodiment of the present invention. Figure 3 As shown, taking the main identification sub-circuit in the overhead contact line power supply system identification circuit, namely the electronic voltage transformer, as an example, the electronic voltage transformer is used to collect the grid voltage signal in real time and output the electrical signal corresponding to the first power supply system identification result to the switching control circuit GVSR, such as a switching relay. Specifically, when the electronic voltage transformer determines that the current section is a DC power supply section, it controls the switching relay to be energized; when the electronic voltage transformer determines that the section is an AC power supply section, it controls the switching relay to be de-energized. Furthermore, Figure 1 and Figure 3 The switch GS shown is a ground protection switch that is normally closed.

[0037] In some embodiments, the overhead contact line power supply system identification circuit includes: a historical consistency evaluation circuit, used to record the historical identification results of each identification sub-circuit when a train passes through the same line section multiple times, and to calculate the historical consistency rate of each identification sub-circuit in the section; and an adaptive selection circuit, electrically connected to the historical consistency evaluation circuit, used to dynamically adjust the identification strategy according to the historical consistency rate of each identification sub-circuit: when the historical consistency rate of a certain identification sub-circuit is higher than a preset threshold, its priority is increased or its single identification result is adopted; when the historical consistency rates of multiple identification sub-circuits are all lower than the preset threshold, the section is marked as a disputed section, the sampling frequency of the main identification sub-circuit is increased, and a maintenance prompt is output.

[0038] Specifically, the historical consistency assessment circuit refers to the hardware or fixed logic circuit used to record the historical identification results of each identification sub-circuit when a train passes through the same line section multiple times, and to calculate the historical consistency rate of each identification sub-circuit in that section. Historical identification results refer to the records of the power supply system identification results output by each identification sub-circuit when the train has passed through a certain line section multiple times in the past. Historical consistency rate refers to the proportion of a particular identification sub-circuit whose identification result matches the final judgment result when passing through the same line section multiple times. The higher the consistency rate, the higher the reliability of the identification sub-circuit in that section. The adaptive selection circuit refers to the circuit electrically connected to the historical consistency assessment circuit, used to dynamically adjust the identification strategy based on the historical consistency rate of each identification sub-circuit. The preset threshold refers to a pre-set critical value used to determine whether the historical consistency rate is high enough, such as 90%. A disputed section refers to a line section where the historical consistency rates of multiple identification sub-circuits are all lower than the preset threshold, indicating that the identification results of each identification sub-circuit in that section are frequently inconsistent, indicating special interference or abnormal line data.

[0039] The historical consistency evaluation circuit has a built-in memory to record the identification results of each identification subcircuit each time the train passes through each line segment. For example, for segment A, the train passes through 100 times, and the ground beacon identification subcircuit outputs DC 98 times and AC 2 times; the soft measurement identification subcircuit outputs DC 95 times and AC 5 times. The historical consistency evaluation circuit calculates that the historical consistency rate of the ground beacon identification subcircuit in segment A is 98%, and the historical consistency rate of the soft measurement identification subcircuit is 95%. These statistical results are stored and continuously updated. The adaptive selection circuit is electrically connected to the historical consistency evaluation circuit and dynamically adjusts the identification strategy based on the historical consistency rate of each identification subcircuit: when the historical consistency rate of a certain identification subcircuit is higher than a preset threshold, such as 95%, the adaptive selection circuit increases the priority of that subcircuit, and may even use its single identification result as the final power supply system identification result for a period of time without voting or verification, thereby improving the response speed. When the historical consistency rates of multiple identification subcircuits are all below a preset threshold, for example, the consistency rate of the ground beacon identification subcircuit is 60% and the consistency rate of the soft measurement identification subcircuit is 55%, it indicates that there is a persistent identification conflict in this segment. The adaptive selection circuit marks this segment as a disputed segment and outputs a maintenance prompt, while increasing the sampling frequency of the main identification subcircuit in this segment to obtain more data to assist in the judgment.

[0040] In some embodiments, the gas path switching valve group U02 is a two-position five-way solenoid valve; or, the gas path switching valve group U02 includes a first two-position five-way solenoid valve and a second two-position five-way solenoid valve connected in series, the control coils of the first two two-position five-way solenoid valve and the second two-position five-way solenoid valve are electrically connected to the switching control circuit GVSR, and when the first two two-position five-way solenoid valve and the second two-position five-way solenoid valve are both switched to the same working position, the corresponding gas path is opened; or, the gas path switching valve group U02 includes a first two-position five-way solenoid valve and a second two-position five-way solenoid valve connected in parallel, the control coils of the first two two-position five-way solenoid valve and the second two-position five-way solenoid valve are electrically connected to the switching control circuit GVSR, and the outlets of the first two two-position five-way solenoid valve and the second two-position five-way solenoid valve are connected to the first pressure setting valve group U041 and the second pressure setting valve group U042 after being merged by a shuttle valve.

[0041] Specifically, such as Figure 2 As shown, a two-position five-way solenoid valve refers to an electromagnetically controlled directional valve with two working positions and five air ports, such as one inlet, two working ports, and two exhaust ports. By energizing one of its two control coils, the valve core can be moved to the corresponding working position, thereby changing the airflow direction. When de-energized, it can either maintain the last position or reset, depending on the design. Series connection refers to two solenoid valves connected end-to-end in the airflow path, meaning the outlet of the first valve is connected to the inlet of the second valve; the air source must pass through both valves sequentially to reach subsequent components. Parallel connection refers to two solenoid valves connected side-by-side in the airflow path, meaning the air source is simultaneously connected to the inlets of both valves, and the outlets of the two valves are combined through a merging element, such as a shuttle valve, for output. A shuttle valve is a pneumatic logic element with two inlets and one outlet. When either inlet has air pressure, the outlet also outputs air pressure; when both inlets have air pressure, the shuttle valve automatically selects the path with the higher pressure to conduct. The shuttle valve can implement OR logic.

[0042] like Figure 2 As shown, the pneumatic switching valve group U02 can be configured as a two-position five-way solenoid valve, with dual coil control and power-off retention. The switching command output by the switching control circuit GVSR directly controls the energization or de-energization of the coil of this two-position five-way solenoid valve. When DC power supply mode is required, the switching control circuit GVSR energizes the first working position control coil, and the two-position five-way solenoid valve switches to the first working position, with the pneumatic source flowing through the first working position to the first pressure setting valve group U041; when AC power supply mode is required, the second working position control coil is energized or the first working position control coil is de-energized, and the two-position five-way solenoid valve switches to the second working position, with the pneumatic source flowing to the second pressure setting valve group U042.

[0043] Alternatively, the pneumatic switching valve group U02 can be configured to include a first two-position five-way solenoid valve and a second two-position five-way solenoid valve connected in series. In this configuration, the two two-position five-way solenoid valves are connected in series in the pneumatic path. The output of the switching control circuit GVSR is simultaneously connected to the corresponding control coils of the two solenoid valves; for example, a DC power supply command simultaneously energizes the first operating position coils of both solenoid valves. The pneumatic path is fully open only when both solenoid valves are switched to the same operating position: the air source enters the first two-position five-way solenoid valve, flows out from its corresponding operating position outlet, enters the inlet of the second two-position five-way solenoid valve, and then flows out from the same operating position outlet of the second two-position five-way solenoid valve, finally reaching the corresponding pressure setting valve group. If either two-position five-way solenoid valve fails to switch to the correct position or becomes stuck, the pneumatic path will be blocked, preventing the incorrect output of the other operating position's pressure.

[0044] Alternatively, the pneumatic switching valve group U02 can be configured to include a first two-position five-way solenoid valve and a second two-position five-way solenoid valve connected in parallel. In this configuration, the two two-position five-way solenoid valves are connected in parallel in the pneumatic path. The output of the switching control circuit GVSR simultaneously controls the two two-position five-way solenoid valves to switch to the same operating position. The air source simultaneously enters the inlet of both two two-position five-way solenoid valves, and the outlets of the two two-position five-way solenoid valves at the same operating position are connected to the two inlets of the shuttle valve. The outlet of the shuttle valve is connected to the first pressure setting valve group U041 and the second pressure setting valve group U042. As long as at least one of the two two-position five-way solenoid valves is working normally and switched to the target operating position, the shuttle valve will output the air pressure for that path. If both paths have air pressure, the path with the higher pressure is selected. Therefore, even if one of the two-position five-way solenoid valves fails and cannot switch, the other two-position five-way solenoid valve can still ensure the pneumatic path is open.

[0045] Therefore, the single two-position five-way solenoid valve solution in this embodiment of the invention has a simple structure, lowest cost, and smallest footprint. The series dual-valve solution implements AND logic, requiring both valves to operate simultaneously for switching, greatly reducing the risk of erroneous switching due to a single valve jamming or coil failure. This aligns with the fault-oriented safety principle of rail transit and is suitable for scenarios with stringent safety requirements. The parallel dual-valve solution implements OR logic, allowing switching to be completed with the normal operation of either valve. This improves system availability and avoids the complete loss of switching function due to a single valve failure, making it suitable for scenarios requiring high availability.

[0046] In some embodiments, combined with Figure 1 and Figure 2The pantograph contact force switching control circuit also includes a pantograph raising and holding interlock circuit, which includes a pantograph raising relay PanUR. The normally open contact of the pantograph raising relay PanUR is connected in series with the front end of the control terminal of the air circuit switching valve group U02, and is used to allow contact force switching control when the pantograph is raised and held. The pantograph raising solenoid valve PanUV is set at the front end of the air circuit of the air circuit switching valve group U02, and is used to control the opening and closing of the air circuit for raising the pantograph. The switching control circuit GVSR is a switching relay, and its coil is electrically connected to the contact network power supply system identification circuit. The normally open contact of the switching relay is connected in series with the first working position control coil of the air circuit switching valve group U02, and the normally closed contact is connected in series with the second working position control coil of the air circuit switching valve group U02.

[0047] Specifically, the pantograph raising and holding interlock circuit refers to a hardware circuit that ensures that contact force switching control is only permitted when the pantograph has been raised and is in a holding state. This circuit achieves the interlock function through the normally open contact of the pantograph raising relay PanUR connected in series. The pantograph raising relay PanUR is a relay used to control the pantograph raising action. Its coil is energized by raising commands, such as the pantograph raising button in the driver's cab or the pantograph raising command from the network control system, and raising conditions met, such as the protective grounding switch being in the working position, the main circuit breaker being open, no pantograph lowering command, or only one end of the pantograph being raised. After energization, the normally open contact of the pantograph raising relay PanUR closes. A normally open contact is a contact that is open when the relay coil is not energized and closes when the coil is energized. A normally closed contact is a contact that is closed when the relay coil is not energized and opens when the coil is energized. The pantograph raising solenoid valve PanUV is a solenoid valve used to control the opening and closing of the pantograph raising air circuit. It is located at the front end of the air circuit of the air circuit switching valve group U02, for example... Figure 2 As shown, the pantograph raising solenoid valve PanUV is located at the front end of the air path of the air path switching valve group U02. When the pantograph raising relay PanUR is energized, the pantograph raising solenoid valve PanUV is energized, the pantograph raising air path is opened, compressed air enters the pantograph air bag, and the pantograph rises.

[0048] A switching relay refers to a specific implementation of a switching control circuit (GVSR), where a single relay is used as the switching control circuit. The coil of the switching relay is electrically connected to the contact network power supply system identification circuit. Its normally open and normally closed contacts are used to control the first and second working positions of the pneumatic switching valve group U02, respectively. Figure 1 In the intermediate switching relay, the normally open contact is the upper contact, and the normally closed contact is the lower contact. (See reference.) Figure 1 and Figure 2 , Figure 1 The valve assembly PanURV in the middle is... Figure 2 The gas path switching valve group U02, such as the upper part of the two-position five-way solenoid valve U02, corresponds to the first working position, which is also the first pressure setting valve group U041. Figure 1The valve assembly PanUFV in the middle is... Figure 2 The lower half of the two-position five-way solenoid valve corresponds to the second working position, which is also the second pressure setting valve group U042.

[0049] The working process of the pantograph raising and holding interlock circuit is as follows: When the driver operates the pantograph raising button or the network system issues a pantograph raising command, and Figure 1 The pantograph raising mechanism is activated when the following conditions are met: the protective grounding switch is in the operating position, the main circuit breaker is open, the pantograph is not disconnected, there is no pantograph lowering command, and only one end of the pantograph is raised. After the pantograph raising relay PanUR is energized, its normally open contacts close. For example... Figure 1 As shown, the normally open contact is connected in series at the front end of the control terminal of the gas path switching valve group U02. This means that the output signal of the switching relay can only reach the control coil of the gas path switching valve group U02 when this normally open contact is closed. Simultaneously, the pantograph lifting solenoid valve PanUV is located at the front end of the gas path of the gas path switching valve group U02. After the pantograph lifting relay PanUR is energized, the pantograph lifting solenoid valve PanUV is energized, the pantograph lifting gas path is opened, and the pantograph is raised and held. Therefore, the contact force switching control is only allowed when the pantograph is successfully raised and held, preventing accidental switching of the gas path when the pantograph is not raised.

[0050] like Figure 1 As shown, after the pantograph raising relay (PanUR) is energized, one set of its normally open contacts closes, forming a self-holding path. Specifically, the control power supply passes through the judgment circuit where the pantograph lowering trigger condition is located, and then splits into two paths: one path returns to the coil of the pantograph raising relay (PanUR) through the closed normally open contacts of the pantograph raising relay (PanUR), i.e., the self-holding path, so that the pantograph raising relay (PanUR) remains energized after the pantograph raising button is released; the other path is connected in series with the coil of the pantograph raising solenoid valve (PanUV), and then grounded through the pantograph raising allow switch, so that the pantograph raising solenoid valve (PanUV) is energized. The pantograph lowering trigger condition is, for example, when the driver operates the pantograph lowering button to issue a pantograph lowering command, or when an emergency power failure condition is triggered. When the pantograph lowering trigger condition is met, the coil of the control pantograph raising relay (PanUR) is de-energized, all its normally open contacts open, causing the coil of the pantograph raising solenoid valve (PanUV) to be de-energized, the pantograph raising solenoid valve (PanUV) to close, cutting off the pantograph raising air path, the pantograph airbag is deflated, and the pantograph descends under the action of gravity. At the same time, because the normally open contact of the pantograph raising relay PanUR is open, the interlock contact connected in series at the front end of the control terminal of the air circuit switching valve group U02 is also open, and the contact force switching control circuit GVSR is disabled to ensure that there will be no malfunction during the pantograph lowering process.

[0051] After the pantograph self-holding circuit is established, the normally open contact of the pantograph relay PanUR closes. The switching relay, as the specific implementation of the switching control circuit GVSR, is as follows: The coil of the switching relay is electrically connected to the contact network power supply system identification circuit. When the contact network power supply system identification circuit outputs the DC power supply system identification result, the coil of the switching relay is energized. Figure 1 The normally open contact of the switching relay (upper contact) is closed, and the normally closed contact (lower contact) is open. This activates the valve group PanURV corresponding to the pneumatic switching valve group U02, energizing the first operating position control coil. The pneumatic switching valve group U02 switches to the first operating position, and the train operates under current supplied with, for example, a 120N contact force. When the identification result indicates AC power supply, the switching relay coil is de-energized. Figure 1 The normally open contact of the switching relay, i.e., the upper contact, is open, and the normally closed contact, i.e., the lower contact, is closed. The valve group PanUFV corresponding to the air circuit switching valve group U02 is turned on, the second working position control coil is energized, the air circuit switching valve group U02 is switched to the second working position, and the train runs with current supplied by, for example, a contact force of 80N.

[0052] See also Figure 2 The valve plate air intake is the starting point of the entire air circuit system, connecting to the vehicle's main air cylinder or air compressor to provide compressed air. The input of filter U01 is connected to the valve plate air intake, used to filter moisture, oil mist, and solid particles from the compressed air, ensuring the cleanliness of subsequent valve assemblies and the pantograph airbag, and extending their service life. The input of the pantograph lifting solenoid valve PanUV is connected to the output of filter U01, and is electrically controlled to control the opening and closing of the pantograph lifting air circuit. When the pantograph lifting relay PanUR is energized, the pantograph lifting solenoid valve PanUV opens, allowing compressed air to enter the subsequent air circuit; when lowering the pantograph, the pantograph lifting solenoid valve PanUV closes, cutting off the air supply. The input of the pantograph lifting throttle valve U03 is connected to the output of the pantograph lifting solenoid valve PanUV, used to adjust the pantograph lifting speed. By adjusting the opening of the throttle valve, the flow rate of compressed air entering the pantograph airbag can be controlled, thus allowing the pantograph to rise at an appropriate speed and avoiding impact on the contact wire.

[0053] The control coil of the air path switching valve assembly U02 is connected in series with the normally open and normally closed contacts of the switching relay, respectively, and the operating position is switched according to the energized and de-energized state of the switching relay. The input end of the first pressure setting valve assembly U041 is connected to the first operating position outlet of the air path switching valve assembly U02, and the output end is connected to the subsequent bow reduction throttle valve U05. The first pressure setting valve assembly U041 has a spring and diaphragm structure inside, which is used to stabilize the compressed air pressure at the air pressure value corresponding to the first preset contact force required for DC power supply. When the air path switching valve assembly U02 is in the first operating position, the compressed air is output after being regulated by the first pressure setting valve assembly U041.

[0054] The input end of the second pressure setting valve group U042 is connected to the second working position outlet of the air path switching valve group U02, and the output end is also connected to the subsequent lowering throttle valve U05. The second pressure setting valve group U042 is similar to the first pressure setting valve group U041, but the pressure setting value is different. It is used to output the air pressure value corresponding to the second preset contact force required for AC power supply. When the air path switching valve group U02 is in the second working position, the compressed air is output after being regulated by the second pressure setting valve group U042.

[0055] The input of the pantograph lowering throttle valve U05 is connected to the output of the first pressure setting valve group U041 and the second pressure setting valve group U042. The output is connected to the pantograph airbag to regulate the lowering speed. During lowering, the airbag's exhaust speed is limited by this valve to prevent the pantograph from falling rapidly and causing damage. The safety valve U06 has a set pressure of 4.5 bar, and its input is connected in parallel to the air path between the lowering throttle valve U05 and the pantograph airbag. When the air path pressure abnormally rises above 4.5 bar, the safety valve U06 automatically opens to release pressure, protecting the pantograph airbag and air path components from overpressure damage. The input of the pressure gauge U07 is also connected in parallel to the main air path to display the current air path pressure value in real time, allowing the driver or maintenance personnel to monitor the actual state of the pantograph-catenary contact force. The pantograph interface is at the end of the air path, connected to the pantograph lifting airbag. Regulated compressed air is sent into the airbag to generate the corresponding lifting force, thereby forming the required pantograph-catenary contact force.

[0056] Therefore, the pantograph raising and holding interlock circuit in this embodiment of the invention ensures the safety of the contact force switching control. Contact force switching is only allowed when the pantograph is raised and held in a stable state, preventing erroneous switching during pantograph raising or lowering that could lead to gas path abnormalities. Furthermore, the pantograph raising solenoid valve PanUV is located at the front end of the gas path of the gas path switching valve group U02, forming a two-stage control. The pantograph raising solenoid valve PanUV controls the on / off state of the main gas path, while the gas path switching valve group U02 controls the direction of the gas path. This hierarchical design ensures that there is no gas pressure downstream of the entire gas path switching valve group U02 when the pantograph is lowered, reducing the risk of leakage and extending component life. Simultaneously, the normally open and normally closed contacts of the switching relay directly drive the two working position control coils of the gas path switching valve group U02, achieving a hardware-level mutually exclusive control. The two working positions cannot be energized simultaneously, fundamentally avoiding the possibility of the solenoid valve being in an intermediate, uncertain state.

[0057] In some embodiments, the pantograph contact force switching control circuit further includes a smooth switching transition valve group. The output terminals of the first pressure setting valve group U041 and the second pressure setting valve group U042 are connected to the lifting airbag via the smooth switching transition valve group. The smooth switching transition valve group is used to make the pressure output to the lifting airbag gradually change from the current contact force to the target contact force at a preset rate of change when the air circuit switching valve group U02 switches to the working position.

[0058] Specifically, the smooth switching transition valve assembly refers to a valve assembly component used to ensure a smooth change in pantograph contact force during the switching process, avoiding abrupt changes. The smooth switching transition valve assembly is connected in series between the pressure setting valve assembly and the lifting airbag, and can control the rate of pressure change. The preset change rate refers to a pre-set value of pressure change per unit time; this rate can be set to a fixed value or vary with factors such as speed, depending on actual needs. The current contact force refers to the actual contact force value currently output by the lifting airbag before the switching action occurs. The target contact force refers to the desired contact force value after the switching is completed, i.e., the first preset contact force or the second preset contact force.

[0059] The outputs of the first pressure setting valve group U041 and the second pressure setting valve group U042 are not directly connected to the lifting airbag. Instead, they first pass through a smooth switching transition valve group, and then from there to the lifting airbag. For example, when the air path switching valve group U02 switches from the first working position to the second working position, the air pressure of the lifting airbag needs to change from the air pressure value corresponding to the current contact force to the air pressure value corresponding to the target contact force. If the switch is performed directly, the air path switching valve group U02 will instantly and completely conduct the output air pressure of the other pressure setting valve group to the lifting airbag, causing a step-like change in the contact force. This sudden change will impact the pantograph's mechanical structure and cause the pantograph-catenary system to detach instantly or be subjected to excessive impact.

[0060] The function of the smooth switching transition valve assembly is to intervene in control during the switching process. It receives control signals from the switching control circuit GVSR. When it detects that the air path switching valve assembly U02 has started to switch, it does not immediately transfer all the air pressure to the pantograph lifting airbag. Instead, it gradually increases or decreases the output air pressure at a preset rate of change. For example, if the preset rate of change is 1 N / s, the current contact force is 80 N, and the target contact force is 120 N, then the smooth switching transition valve assembly will linearly increase the output pressure from 80 N to 120 N within 10 seconds, causing the pantograph to rise slowly.

[0061] Therefore, this embodiment of the invention eliminates the abrupt change in contact force during switching by adding a smooth switching transition valve group, avoiding mechanical impact on the pantograph-catenary system, reducing fatigue damage to the pantograph and catenary, and extending equipment life. Simultaneously, it reduces the risk of arcing or disconnection caused by sudden changes in contact force during switching, especially during high-speed switching, where a smooth transition maintains stable contact between the pantograph and catenary, improving current collection quality. The preset change rate can be dynamically adjusted according to train speed, track conditions, etc., ensuring smooth switching while completing the switching within a limited distance, demonstrating good engineering adaptability.

[0062] In some embodiments, the pantograph contact force switching control circuit further includes: a cooperative control signal output interface, which is electrically connected to the overhead contact line power supply system identification circuit and is used to output the power supply system identification result to the train traction converter and the train braking system; the train traction converter is used to switch control parameters according to the power supply system identification result, and the train braking system is used to adjust the maximum electric braking force limit according to the power supply system identification result.

[0063] Specifically, the coordinated control signal output interface refers to the hardware interface circuit used to extract the power supply system identification result signal from the overhead contact system power supply system identification circuit and simultaneously output it to the train traction converter and the train braking system. Control parameters refer to the internal setpoints required for the traction converter to operate under different power supply systems, including but not limited to rectifier control mode, switching frequency, modulation strategy, voltage setpoint, and current limit. The train braking system refers to the system used to control train deceleration and stopping, including electric braking and air braking; here, it refers to the electric braking component. The maximum electric braking force limit refers to the maximum electric braking force value that the braking system is allowed to output. Under different overhead contact system conditions, the electric braking force is limited by the absorption capacity of the overhead contact system or the pantograph-catenary bearing capacity.

[0064] The overhead contact line power supply system identification circuit, while outputting the power supply system identification result to the switching control circuit, also simultaneously sends the identification result to the train traction converter and the train braking system via the coordinated control signal output interface. For the train traction converter, when the power supply system identification result is DC power supply, the traction converter automatically switches to DC control mode, for example, adjusting the control strategy of the four-quadrant rectifier to uncontrolled rectification or pulse width modulation rectification, setting the corresponding DC bus voltage target value, and adjusting the switching frequency to adapt to DC ripple characteristics. When the identification result is AC power supply, the traction converter switches to AC control mode, for example, enabling the grid-side harmonic suppression algorithm and adjusting the grid-side voltage amplitude and phase synchronization control parameters. This synchronous switching ensures that the traction converter always adapts to the current power supply system in the optimal way, improving power conversion efficiency. For the train braking system, when the power supply system identification result is DC power supply, the braking system knows that the current contact network is DC power supply, and its contact network has a strong ability to absorb braking energy, which allows for a larger electric braking force limit. When the identification result is AC power supply, the braking system takes into account the energy absorption limit of the AC contact network and the impact on the pantograph and contact network, and appropriately reduces the maximum electric braking force limit, and prioritizes the use of air braking to supplement it, so as to avoid excessive electric braking force causing pantograph and contact network arcing or contact network overvoltage.

[0065] Therefore, this embodiment of the invention achieves coordinated control of the mechanical and electrical systems. A single power supply system identification signal simultaneously drives the switching of contact force and traction converter parameters, ensuring consistency of electromechanical states and avoiding the risk of runaway due to asynchronous system switching. The maximum electric braking force limit is dynamically adjusted according to the power supply system, fully utilizing the regenerative braking capability of the DC power supply line while avoiding pantograph-catenary damage to the AC power supply line caused by excessive electric braking force.

[0066] In some embodiments, the pantograph contact force switching control circuit further includes: a time delay holding circuit, electrically connected to the contact network power supply system identification circuit and the switching control circuit respectively, for maintaining the state of the switching control circuit for a preset duration when the grid voltage signal disappears; and / or, a grid voltage pre-identification circuit, electrically connected to the contact network power supply system identification circuit and the switching control circuit respectively, for predicting the power supply system based on the establishment characteristics of the grid voltage signal during the pantograph raising process, and outputting the prediction result to the switching control circuit before the pantograph is fully raised, so that the air circuit switching valve group switches to the corresponding working position in advance.

[0067] Specifically, the delay-holding circuit refers to a hardware circuit used to maintain the state of the switching control circuit for a preset duration when the grid voltage signal disappears. The disappearance of the grid voltage signal refers to the situation where the train enters a de-energized section, such as the neutral section of an AC power supply line or when the pantograph is briefly disconnected from the grid, and the electronic voltage transformer cannot detect normal grid voltage. The preset duration refers to a pre-set time length, which must be greater than the maximum duration for the train to pass through the de-energized section. The grid voltage pre-identification circuit refers to a hardware circuit that, during the pantograph raising process, uses the establishment characteristics of the grid voltage signal, such as the rise rate and zero-crossing characteristics, to pre-determine the power supply system. The prediction result refers to the power supply system judgment result output by the grid voltage pre-identification circuit before the pantograph is fully raised.

[0068] The time-delay holding circuit is connected in series between the overhead contact line power supply system identification circuit and the switching control circuit. When the train enters a de-energized section, the grid voltage signal output by the electronic voltage transformer disappears. Without the time-delay holding circuit, the switching control circuit might mistakenly switch the pneumatic switching valve group back to its default operating position (e.g., AC position) due to the loss of the drive signal, causing unnecessary changes in the pantograph contact force within the de-energized section. The function of the time-delay holding circuit is to start timing at the moment the grid voltage signal disappears and maintain the original state of the switching control circuit for a preset duration. When the train leaves the de-energized section and grid voltage is restored within the preset duration, the state of the switching control circuit remains unchanged, preventing erroneous switching. If the train remains in a de-energized state for an extended period, the time-delay holding circuit is allowed to change its state; in this case, the train is generally considered to have entered a fixed de-energized section.

[0069] The grid voltage pre-identification circuit is connected in parallel to the contact network power supply system identification circuit and is also electrically connected to the switching control circuit. In the initial stage of pantograph raising, i.e., before the pantograph is fully raised and the grid voltage is being established, traditional electronic voltage transformers require a certain amount of time to stabilize and output the identification result. The grid voltage pre-identification circuit utilizes the transient characteristics of the grid voltage signal to predict in advance. When the DC-powered grid voltage is established, the voltage rises monotonically from 0 to the rated value with a smooth waveform; when the AC-powered grid voltage is established, the voltage rises sinusoidally from 0, exhibiting zero-crossing points and alternating polarities. By detecting parameters such as the voltage rise rate and zero-crossing characteristics, the grid voltage pre-identification circuit outputs the prediction result to the switching control circuit before the pantograph is fully raised, causing the pneumatic switching valve group to switch to the corresponding operating position in advance. Once the pantograph is fully raised and the electronic voltage transformer outputs a stable identification result, the system uses the stable result as the standard.

[0070] Therefore, the delay-holding circuit in this embodiment of the invention avoids erroneous switching caused by the disappearance of grid voltage when the train passes through a power-deprived section. The grid voltage pre-identification circuit enables advanced switching, further shortening the total time from identification to switching completion, ensuring that the contact force is ready as soon as the train enters the section with the new power supply system, thus avoiding pantograph-catenary anomalies caused by switching lag. The two circuits complement each other; the pre-identification circuit solves the switching delay problem, and the delay-holding circuit solves the erroneous operation problem in power-deprived areas, together forming a complete solution for dealing with grid voltage anomalies.

[0071] In some embodiments, the pantograph contact force switching control circuit further includes: a catenary type identification circuit, used to identify the current catenary type and output the type identification result; wherein the type includes at least rigid catenary and flexible catenary; and a preset value determination unit, electrically connected to the catenary power supply system identification circuit and the catenary type identification circuit respectively, used to determine the corresponding preset contact force as a first preset contact force or a second preset contact force according to at least one of the current catenary power supply system, the current catenary type, and the current train running speed.

[0072] Specifically, the overhead contact line type identification circuit refers to the hardware circuit module used to identify whether the current overhead contact line is rigid or flexible. Rigid overhead contact lines use a busbar structure with high vertical stiffness; flexible overhead contact lines use a dropper suspension structure with low vertical stiffness. The type identification result refers to the electrical signal output by the overhead contact line type identification circuit, indicating whether the current overhead contact line is rigid or flexible. The preset value determination unit refers to the circuit unit electrically connected to both the overhead contact line power supply system identification circuit and the overhead contact line type identification circuit, used to determine the corresponding preset contact force based on at least one of the power supply system, overhead contact line type, and train speed. Train speed refers to the instantaneous speed of the train, which can be obtained through a speed sensor or speed measuring radar.

[0073] The overhead contact system power supply system identification circuit outputs the power supply system identification result, and the overhead contact system type identification circuit independently outputs the type identification result. The preset value determination unit simultaneously receives both identification results and determines the preset contact force according to preset rules or a lookup table. For example, the following correspondence can be established: DC power supply and rigid overhead contact system correspond to a larger first preset contact force, such as 120N; DC power supply and flexible overhead contact system correspond to a medium value, such as 100N; AC power supply and flexible overhead contact system correspond to a smaller second preset contact force, such as 80N; AC power supply and rigid overhead contact system correspond to a medium-to-small value, such as 90N.

[0074] The preset value determination unit can further incorporate train speed as a third dimension. When the speed is high, a speed-related compensation amount is added to the base value to counteract the aerodynamic lift force. The determined preset contact force is output to either the first or second pressure setting valve group as the final target pressure for setting.

[0075] Therefore, this embodiment of the invention achieves joint identification and decision-making regarding power supply system and catenary type, covering more complex real-world line scenarios, such as combinations of DC power supply with flexible catenary and AC power supply with rigid catenary, thus improving the adaptability of the solution to different lines. Through the preset value determination unit, the preset contact force can be flexibly adjusted according to multiple dimensions to achieve refined control and further optimize pantograph-catenary matching.

[0076] In some embodiments, the pantograph contact force switching control circuit further includes: an acceleration detection circuit electrically connected to the switching control circuit, used to predict the power supply restoration time based on the coasting time when the train enters the coasting state from the traction state according to the train's acceleration change, and to output a pre-trigger signal to the switching control circuit within a preset time before the power supply is restored.

[0077] Specifically, the acceleration detection circuit refers to the hardware circuit used to detect the instantaneous acceleration of the train, implemented based on an acceleration sensor. Traction state refers to the state where the train's traction system outputs power, and the train accelerates or moves at a constant speed. Coasting state refers to the state where the train's traction system stops outputting power, and the train coasts due to inertia, decelerating. Coasting time refers to the time elapsed from entering the coasting state to the resumption of traction or stopping. Power restoration moment refers to the moment when the train exits a power-deprived section or regains power. Pre-trigger signal refers to the electrical signal output within a preset time before power restoration, used to prepare for switching commands in advance.

[0078] When a train operates on a hybrid AC / DC line, it will pass through sections without power, such as the neutral section of an AC line. Upon entering a section without power, the traction system loses power, the train loses traction, and generates negative acceleration under the influence of resistance. The acceleration detection circuit monitors the train's acceleration changes in real time. When the acceleration changes from zero or a positive value to a negative value and persists for a certain period, combined with the traction system power failure signal, it can be determined that the train has entered a coasting state from traction mode. After entering the coasting state, the system predicts the duration of coasting based on pre-stored line data, such as the length of the section without power, the current speed, or through machine learning algorithms, thereby estimating the approximate time when power will be restored. Within a preset time before the predicted power restoration time, the acceleration detection circuit outputs a pre-trigger signal to the switching control circuit. Upon receiving the pre-trigger signal, the switching control circuit pre-positions the switching relay to the state corresponding to the power supply mode to be restored. When the grid voltage is actually restored, the air circuit switching valve assembly is already in the correct operating position, and the contact force is immediately adapted, avoiding pantograph-catenary abnormalities caused by switching delays.

[0079] Therefore, this embodiment of the invention utilizes train dynamics as a predictive means for power-deprived sections, eliminating the need for high-precision positioning or ground beacons and reducing system costs. It achieves pre-switching before power restoration, eliminates the identification and processing delays after grid voltage restoration, and ensures that contact force switching and power restoration are completed synchronously, further improving the timeliness of switching and pantograph-catenary tracking.

[0080] In summary, this invention achieves for the first time the identification of the power supply system of the overhead contact line by the train, and for the first time online switching control of the pantograph-catenary contact force within a single line, ensuring pantograph-catenary following throughout the entire line's operating section. Simultaneously, this invention introduces for the first time a two-position five-way solenoid valve on the pantograph valve plate, employing dual-coil control and featuring a power-off retention function, ensuring safety and reliability. The pantograph raising solenoid valve (PanUV) and the contact force switching solenoid valve are controlled separately. The pantograph raising solenoid valve (PanUV) is used for pantograph raising and lowering control, while the contact force switching solenoid valve is used for AC / DC contact pressure adjustment. Furthermore, the front end of the switching control circuit GVSR is connected in series with the pantograph raising and holding signal, i.e., the normally open contact of the pantograph raising relay (PanUR). Contact force switching control is only permitted when the pantograph is raised and held, ensuring the safety of the control logic.

[0081] Figure 4 This is a schematic flowchart of a pantograph contact force switching control method provided in an embodiment of the present invention. The pantograph contact force switching control method can be executed by the pantograph contact force switching control circuit provided in this embodiment of the invention, for example, by a switching control circuit. Figure 4 As shown, the pantograph contact force switching control method includes the following steps: S101. Obtain the power supply system identification result output by the contact network power supply system identification circuit; wherein, the power supply system identification result indicates whether the current contact network is powered by DC or AC.

[0082] S102. When the power supply system identification result is DC power supply, the control air circuit switching valve group is switched to the first working position so that the air circuit supplies air to the pantograph lifting airbag through the first pressure setting valve group, and sets the first preset contact force in an open-loop manner.

[0083] S103. When the power supply system identification result is AC power supply, the control air circuit switching valve group is switched to the second working position so that the air circuit supplies air to the pantograph lifting air bag through the second pressure setting valve group, and sets the second preset contact force in an open-loop manner.

[0084] Specifically, setting in an open-loop manner means that when setting the contact force, it does not rely on real-time feedback monitoring of the actual contact force value, but directly outputs a control signal based on a preset correspondence, i.e., DC power supply corresponds to the first preset contact force and AC power supply corresponds to the second preset contact force, so that the air circuit and pressure setting valve group execute the preset force value.

[0085] For DC power supply, the switching control circuit GVSR executes DC power supply mode, outputting a control signal to energize the switching relay, causing the air path switching valve group U02 to switch to the first working position. After the first working position is activated, compressed air flows through the first pressure setting valve group U041, which adjusts the air pressure to the value corresponding to the first preset contact force, and then sends it to the pantograph's lifting airbag. Throughout the process, the actual pressure of the lifting airbag is not monitored to ensure the target value; output accuracy is only guaranteed by the mechanical characteristics of the pressure setting valve group, hence it is called open-loop setting. For AC power supply, the switching control circuit GVSR executes AC power supply mode, outputting a control signal to switch the air path switching valve group U02 to the second working position. Compressed air flows through the second pressure setting valve group U042, outputting the air pressure corresponding to the second preset contact force to the lifting airbag, also in an open-loop setting manner.

[0086] Therefore, the open-loop setting in this embodiment of the invention avoids problems such as sensor noise, delay and PID (Proportional-Integral-Derivative) parameter tuning, resulting in fast switching speed, no overshoot and no oscillation, making it particularly suitable for discrete and deterministic switching scenarios between AC and DC.

[0087] This invention also provides a rail train, including the pantograph contact force switching control circuit described in the above embodiments, and therefore possesses the beneficial effects described in the above embodiments, which will not be repeated here. Exemplarily, the rail train may be, for example but not limited to, a suburban railway train, an intercity EMU, or a mainline EMU on a specific line.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pantograph contact force switching control circuit, characterized in that, include: A power supply system identification circuit for overhead contact lines is used to identify the current power supply system of the overhead contact lines and output the power supply system identification result; wherein, the power supply system includes at least DC power supply and AC power supply; A switching control circuit is electrically connected to the contact network power supply system identification circuit and is used to output a switching command based on the power supply system identification result. A gas path switching valve assembly has a first working position and a second working position. The control terminal of the gas path switching valve assembly is electrically connected to the switching control circuit and is used to switch to the first working position or the second working position according to the switching command. A first pressure setting valve group and a second pressure setting valve group, wherein the input end of the first pressure setting valve group is connected to the first working position and is used to output the first preset contact force required for the DC power supply; the input end of the second pressure setting valve group is connected to the second working position and is used to output the second preset contact force required for the AC power supply; the output ends of the first pressure setting valve group and the second pressure setting valve group are both connected to the pantograph lifting airbag.

2. The pantograph contact force switching control circuit according to claim 1, characterized in that, The contact wire power supply system identification circuit includes: The main identification sub-circuit is an electronic voltage transformer, used to acquire the mains voltage signal in real time and output the first power supply system identification result; The backup identification sub-circuit is used to independently identify the current power supply system of the overhead contact line and output the identification result of the second power supply system. A priority selection circuit is electrically connected to the main identification sub-circuit and the backup identification sub-circuit, respectively, and is used to use the first power supply system identification result as the final power supply system identification result when the output of the main identification sub-circuit is determined to be valid, and to use the second power supply system identification result as the final power supply system identification result when the output of the main identification sub-circuit is confirmed to be invalid.

3. The pantograph contact force switching control circuit according to claim 1, characterized in that, The pneumatic switching valve assembly is a two-position five-way solenoid valve; or... The pneumatic switching valve assembly includes a first two-position five-way solenoid valve and a second two-position five-way solenoid valve connected in series. The control coils of both valves are electrically connected to the switching control circuit. When both valves are switched to the same operating position, the corresponding pneumatic path is opened; or... The gas path switching valve group includes a first two-position five-way solenoid valve and a second two-position five-way solenoid valve connected in parallel. The control coils of the first two-position five-way solenoid valve and the second two-position five-way solenoid valve are electrically connected to the switching control circuit. The gas outlets of the first two-position five-way solenoid valve and the second two-position five-way solenoid valve are connected to the first pressure setting valve group and the second pressure setting valve group after being merged by a shuttle valve.

4. The pantograph contact force switching control circuit according to claim 1, characterized in that, Also includes: The pantograph holding interlock circuit includes a pantograph relay, the normally open contact of which is connected in series with the front end of the control terminal of the air circuit switching valve group, for allowing contact force switching control when the pantograph is raised and held. The pantograph solenoid valve is located at the front end of the air circuit of the air circuit switching valve group for controlling the opening and closing of the pantograph air circuit. The switching control circuit is a switching relay, whose coil is electrically connected to the contact network power supply system identification circuit. The normally open contact of the switching relay is connected in series with the first working position control coil of the gas path switching valve group, and the normally closed contact is connected in series with the second working position control coil of the gas path switching valve group.

5. The pantograph contact force switching control circuit according to any one of claims 1-4, characterized in that, Also includes: A collaborative control signal output interface is electrically connected to the overhead contact line power supply system identification circuit, and is used to output the power supply system identification result to the train traction converter and the train braking system. The train traction converter is used to switch control parameters according to the power supply system identification result, and the train braking system is used to adjust the maximum electric braking force limit according to the power supply system identification result.

6. The pantograph contact force switching control circuit according to any one of claims 1-4, characterized in that, Also includes: The delay holding circuit is electrically connected to the contact network power supply system identification circuit and the switching control circuit, respectively, and is used to maintain the state of the switching control circuit for a preset time when the grid voltage signal disappears; And / or, The grid voltage pre-identification circuit is electrically connected to the contact network power supply system identification circuit and the switching control circuit, respectively. It is used to predict the power supply system based on the establishment characteristics of the grid voltage signal during the pantograph raising process, and output the prediction result to the switching control circuit before the pantograph is fully raised, so that the air circuit switching valve group can switch to the corresponding working position in advance.

7. The pantograph contact force switching control circuit according to any one of claims 1-4, characterized in that, Also includes: A contact wire type identification circuit is used to identify the type of the current contact wire and output the type identification result; wherein, the type includes at least rigid contact wire and flexible contact wire; The preset value determination unit is electrically connected to the overhead contact line power supply system identification circuit and the overhead contact line type identification circuit, respectively, and is used to determine the corresponding preset contact force as the first preset contact force or the second preset contact force based on at least one of the current overhead contact line power supply system, the current overhead contact line type, and the current train running speed.

8. The pantograph contact force switching control circuit according to any one of claims 1-4, characterized in that, Also includes: An acceleration detection circuit, electrically connected to the switching control circuit, is used to predict the power supply restoration time based on the coasting time when the train enters the coasting state from the traction state according to the change in the train's acceleration, and to output a pre-trigger signal to the switching control circuit within a preset time before the power supply is restored.

9. A method for switching control of pantograph contact force, characterized in that, Performed by the pantograph contact force switching control circuit as described in any one of claims 1-8, comprising: Obtain the power supply system identification result output by the overhead contact system power supply system identification circuit; wherein, the power supply system identification result indicates whether the current overhead contact system is powered by DC or AC. When the power supply system identification result is DC power supply, the air path switching valve group is controlled to switch to the first working position, so that the air path supplies air to the pantograph lifting airbag through the first pressure setting valve group, and the first preset contact force is set in an open-loop manner. When the power supply system identification result is AC power supply, the air path switching valve group is controlled to switch to the second working position, so that the air path supplies air to the pantograph lifting airbag through the second pressure setting valve group, and the second preset contact force is set in an open-loop manner.

10. A rail train, characterized in that, Includes the pantograph contact force switching control circuit as described in any one of claims 1-8.

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