Railway train

Abstract

The rail train comprises a high-voltage backflow grounding platform, a low-voltage backflow grounding platform and a traction inverter arranged in a vehicle body, and a traction motor; wherein the high-voltage backflow grounding platform is arranged at a first end of the vehicle body, the low-voltage backflow grounding platform is arranged at a second end of the vehicle body, so that the high voltage and the low voltage are isolated; the distance between the first end and the second end is >10m; the shell of the traction inverter and the shell of the traction motor are directly connected, so as to shorten the electrical transmission path between the traction inverter and the traction motor.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of rail vehicle technology, and more particularly, to a rail train. BACKGROUND

[0002] With the acceleration of urbanization, the safety, stability and reliability of rail trains, as an important part of urban transportation, have attracted more and more attention. In a rail train, as the core components of the electrical system, the traction inverter and the traction motor are the key to ensure the normal operation of the train.

[0003] In the design of a rail train, to ensure the safety of the rail train, the electrical connection of the traction inverter and the traction motor is usually connected to the light rail through the shell of the traction motor, and the light rail is connected to the shell of the traction inverter through a grounding resistor.

[0004] In the process of implementing the present disclosure, the inventors have found that at least the following problems exist in the related art: the electrical transmission path from the traction motor to the traction inverter is relatively long, which increases the risk of electromagnetic interference and reduces the energy transmission efficiency. Moreover, the motor bearing voltage of the traction motor is relatively high, which causes damage to the motor bearing, shortens the service life of the motor, and reduces the operation safety of the rail train. SUMMARY

[0005] Therefore, the present disclosure provides a rail train, which includes: a high-voltage backflow grounding platform, a low-voltage backflow grounding platform and a traction inverter arranged in a vehicle body; and a traction motor; wherein the high-voltage backflow grounding platform is arranged at a first end of the vehicle body, and the low-voltage backflow grounding platform is arranged at a second end of the vehicle body, so as to isolate the high voltage and the low voltage; the distance between the first end and the second end is > 10 m; the shell of the traction inverter and the shell of the traction motor are directly connected, so as to shorten the electrical transmission path between the traction inverter and the traction motor.

[0006] According to an embodiment of the present disclosure, the rail train further includes a grounding resistor and a terminal grounding device, and the grounding resistor is arranged between the vehicle body and the terminal grounding device, so as to shorten the electrical transmission path between the vehicle body, the grounding resistor and the terminal grounding device.

[0007] According to an embodiment of the present disclosure, the material of the grounding resistor includes silicon carbide, and the inductance parameter of the grounding resistor is < 0.5 µH.

[0008] According to an embodiment of the present disclosure, the rail train further comprises: an auxiliary inverter and a high-voltage axle grounding end; wherein the electric transmission path between the high-voltage return flow grounding platform and the high-voltage axle grounding end, the electric transmission path between the high-voltage return flow grounding platform and the traction inverter, and the electric transmission path between the high-voltage return flow grounding platform and the auxiliary inverter are all equal.

[0009] According to an embodiment of the present disclosure, the capacity of the terminal grounding device is configured to be determined based on the return flow parameters between the high-voltage return flow grounding platform and the traction inverter, and the return flow parameters between the high-voltage return flow grounding platform and the auxiliary inverter.

[0010] According to an embodiment of the present disclosure, the ratio of the capacity of the high-voltage axle grounding end to the capacity of the terminal grounding device is configured to be 1:2-1:3.

[0011] According to an embodiment of the present disclosure, the wire between the high-voltage return flow grounding platform and the traction inverter is a return flow line, and the wire between the high-voltage return flow grounding platform and the auxiliary inverter is a return flow line.

[0012] According to an embodiment of the present disclosure, the rail train further comprises: a low-voltage axle grounding end, a direct-current load and an alternating-current load; wherein the low-voltage axle grounding end is connected with the low-voltage return flow grounding platform; and the direct-current load and the alternating-current load are both connected with the low-voltage return flow grounding platform.

[0013] According to an embodiment of the present disclosure, the ratio of the capacity of the low-voltage axle grounding end to the capacity of the terminal grounding device is configured to be 1:4-1:5.

[0014] According to an embodiment of the present disclosure, the wire between the low-voltage return flow grounding platform and the auxiliary inverter is a load connection line, the wire between the low-voltage return flow grounding platform and the direct-current load is a load connection line, and the wire between the low-voltage return flow grounding platform and the alternating-current load is a load connection line.

[0015] According to an embodiment of the present disclosure, by setting the high-voltage return flow grounding platform at the first end of the car body and the low-voltage return flow grounding platform at the second end of the car body, the high-voltage system and the low-voltage system can be physically isolated, the mutual influence between the high-voltage return flow grounding platform and the low-voltage return flow grounding platform in the case of electrical failure of the rail train is reduced, and the safety of the rail train is ensured. Meanwhile, under the premise of ensuring the safety of the rail train, by directly connecting the shell of the traction inverter and the shell of the traction motor, the electric transmission path between the traction inverter and the traction motor is shortened, the electromagnetic interference is reduced, and the energy transmission efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which:

[0017] Figure 1 A structural schematic diagram of a rail train according to an embodiment of the present disclosure is schematically shown;

[0018] Figure 2 A structural schematic diagram of a traction inverter according to an embodiment of the present disclosure is schematically shown;

[0019] Figure 3 An installation position schematic diagram of a grounding resistor according to an embodiment of the present disclosure is schematically shown; and

[0020] Figure 4 A structural schematic diagram of a rail train according to another embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It is to be understood, however, that the description is merely exemplary and is intended to provide a thorough understanding of the present disclosure. The following description, given together with the accompanying drawings, is intended to provide a thorough understanding of the present disclosure. However, it is apparent that one or more embodiments can be implemented without the specific details, as is obvious to those skilled in the art. Moreover, in the following description, descriptions of well-known structures and techniques have been omitted to avoid unnecessarily obscuring the concept of the present disclosure.

[0022] The terms used herein are merely used to describe specific embodiments, and are not intended to limit the present disclosure. The terms "include", "comprise" and the like used herein indicate the presence of the described features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0023] All terms used herein, including technical and scientific terms, have meanings commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the specification, and should not be interpreted in an idealized or overly formal manner.

[0024] With the acceleration of urbanization, the safety, stability and reliability of rail trains, as an important part of urban transportation, have attracted more and more attention. In a rail train, the traction inverter and traction motor, as core components of the electrical system, are the key to ensuring the normal operation of the train.

[0025] In the design of a rail train, in order to ensure the safety of the rail train, the electrical connection of the traction inverter and the traction motor is usually connected to the optical track through the shell of the traction motor, and the optical track is connected to the shell of the traction inverter through a grounding resistor.

[0026] In the process of implementing the present disclosure, the inventors found that at least the following problems exist in the related art: the electrical transmission path from the traction motor to the traction inverter is long, which increases the risk of electromagnetic interference and reduces energy transmission efficiency. Moreover, the motor bearing voltage of the traction motor is high, which causes damage to the motor bearing, shortens the service life of the motor, and reduces the running safety of the rail train. The principle of generating the motor bearing voltage is as follows: in the long-distance electrical transmission path, the transmission cable and transmission line will cause common-mode voltage in the transmission signal. The common-mode voltage acts on the oil film of the motor bearing, and through the medium of the oil film, the bearing voltage is generated inside the motor bearing. When the bearing voltage caused by the common-mode voltage exceeds the breakdown voltage threshold of the oil film, the insulation performance of the oil film will be destroyed, and the surface of the motor bearing will have a transient discharge phenomenon, causing an electro-erosion effect, damaging the surface of the motor bearing, and causing the motor bearing to wear out or fail prematurely, thereby affecting the performance and service life of the entire motor.

[0027] Therefore, the embodiments of the present disclosure provide a rail train, by setting a high-voltage return ground platform at a first end of a vehicle body and a low-voltage return ground platform at a second end of the vehicle body, the high-voltage system and the low-voltage system can be physically isolated, the mutual influence between the high-voltage return ground platform and the low-voltage return ground platform under the condition of an electrical fault of the rail train is reduced, and the safety of the rail train is ensured. At the same time, under the premise of ensuring the safety of the rail train, by directly connecting the shell of the traction inverter and the shell of the traction motor, the electrical transmission path between the traction inverter and the traction motor is shortened, the electromagnetic interference is reduced, and the energy transmission efficiency is improved.

[0028] Figure 1 A structural schematic diagram of a rail train according to an embodiment of the present disclosure is schematically shown.

[0029] As shown in Figure 1 , the rail train 100 includes a high-voltage return ground platform 111, a low-voltage return ground platform 112, and a traction inverter 113 arranged in a vehicle body 110, and a traction motor 120. The high-voltage return ground platform 111 is arranged at a first end of the vehicle body 110, and the low-voltage return ground platform 112 is arranged at a second end of the vehicle body 110, so that the high-voltage and the low-voltage are isolated. The distance between the first end and the second end is > 10 m. The shell of the traction inverter 113 and the shell of the traction motor 120 are directly connected to shorten the electrical transmission path between the traction inverter 113 and the traction motor 120.

[0030] According to an embodiment of the present disclosure, the high-voltage return ground platform 111 can provide a low-impedance electrical transmission path, which can be used to guide the high-voltage current to return to the power supply, and provide a current return path for the high-voltage system. The voltage level of the high-voltage system includes but is not limited to 750-1500V, and the high-voltage system can include a power supply system that provides power for the traction motor 120 and the traction inverter 113. The low-voltage return ground platform 112 can be used to provide a current return path for the low-voltage system, provide a current return path for the low-voltage system, and ensure the safe operation of the low-voltage electrical equipment to prevent electrical failure. The voltage level of the low-voltage system includes but is not limited to 110-380V, and the low-voltage system can include lighting systems, air conditioning systems, ventilation systems, etc.

[0031] According to an embodiment of the present disclosure, the traction inverter 113 can convert a direct-current power supply into an alternating-current power supply and transmit the alternating-current power supply to the traction motor 120 arranged outside the vehicle body 110, so that the traction motor 120 drives the rail train 100 to run.

[0032] According to an embodiment of the present disclosure, the shell of the traction inverter 113 and the shell of the traction motor 120 can be directly connected by a cable or a busbar.

[0033] According to an embodiment of the present disclosure, by arranging the high-voltage return ground platform 111 at the first end of the vehicle body 110 and the low-voltage return ground platform 112 at the second end of the vehicle body 110, the high-voltage system and the low-voltage system can be physically isolated, the mutual influence between the high-voltage return ground platform 111 and the low-voltage return ground platform 112 under the condition of electrical failure of the rail train 100 can be reduced, and the safety of the rail train 100 can be ensured. By arranging a distance > 10m between the first end and the second end, the electromagnetic interference between the high-voltage return ground platform 111 and the low-voltage return ground platform 112 can be reduced, the integrity and stability of the transmission current can be improved, and the safety of the rail train 100 can be ensured.

[0034] According to an embodiment of the present disclosure, under the premise of ensuring the safety of the rail train 100, the shell of the traction inverter 113 and the shell of the traction motor 120 are directly connected to shorten the electrical transmission path between the traction inverter 113 and the traction motor 120, reduce electromagnetic interference, and improve energy transmission efficiency. Moreover, based on the principle that electromagnetic interference is usually transmitted through the path with the smallest impedance, directly connecting the shell of the traction inverter 113 and the shell of the traction motor 120 can make the electromagnetic interference return to the source, i.e., the traction motor 120, so that the electromagnetic interference does not overflow into the vehicle body 110. In addition, directly connecting the shell of the traction motor 120 and the shell of the traction inverter 113 is conducive to reducing the motor bearing voltage, reducing the damage of bearing overcurrent, and prolonging the service life of the motor.

[0035] Figure 2A structural schematic diagram of a traction inverter is shown schematically according to an embodiment of the present disclosure.

[0036] As shown in Figure 2 , the traction inverter 113 includes an inverter module 1131, a wiring copper bar 1132, a filter capacitor CE, a resistor R, and a support capacitor C. The inverter module 1131 can convert a direct current power supply into an alternating current power supply for use by the traction motor. The inverter module 1131 can include a plurality of power semiconductor devices, such as Insulated Gate Bipolar Transistors (IGBTs). The filter capacitor CE can be used to smooth the alternating current output by the inverter module 1131, reduce voltage fluctuations, and improve the waveform of the alternating current output by the inverter module 1131. The filter capacitor CE can be connected with the inverter module 1131 and the wiring copper bar 1132 to form a circuit on the direct current side. The wiring copper bar 1132 can serve as a conductor for electrical connections and be responsible for transmitting current. The wiring copper bar 1132 can be used to connect components such as the inverter module 1131, the filter capacitor CE, and the resistor R. The support capacitor C can be used to improve the dynamic response of the inverter module 1131, provide additional energy storage, and help stabilize the direct current bus voltage. Figure 2 P in the formula represents the positive terminal of the support capacitor C, and N represents the negative terminal of the support capacitor C.

[0037] Figure 3 A schematic diagram of the installation position of the grounding resistor is shown schematically according to an embodiment of the present disclosure.

[0038] As shown in Figure 3 , the rail train also includes a grounding resistor 130 and a terminal grounding device 140, and the grounding resistor 130 is arranged between the car body 110 and the terminal grounding device 140 to shorten the electrical transmission path between the car body 110, the grounding resistor 130, and the terminal grounding device 140.

[0039] According to an embodiment of the present disclosure, the rail train also includes a bogie 150, which can be used to connect the rail vehicle and the track. The traction motor 120 can be mounted on the bogie 150 to directly drive the rotation of the wheel set of the bogie 150. The terminal grounding device 140 can also be mounted on the bogie 150 to provide electrical grounding and ensure the safety of the electrical system.

[0040] According to an embodiment of the present disclosure, the grounding resistor 130 is arranged between the car body 110 and the terminal grounding device 140 and is close to the bogie 150. The car body 110, the grounding resistor 130, the terminal grounding device 140, the high-voltage return grounding platform 111, and the traction inverter 113 are sequentially electrically connected. Figure 3 The dashed line in the formula represents electrical connection through the working ground wire, and the solid line represents electrical connection through the protection ground wire.

[0041] According to an embodiment of the present disclosure, by arranging the grounding resistor 130 between the vehicle body 110 and the terminal grounding device 140, the electrical transmission path between the vehicle body 110, the grounding resistor 130 and the terminal grounding device 140 is shortened, the line impedance is reduced, the vehicle body voltage is reduced, and the damage of the vehicle body sensor caused by the over-high vehicle body voltage is reduced without increasing additional design.

[0042] According to an embodiment of the present disclosure, the material of the grounding resistor includes silicon carbide, and the inductance parameter of the grounding resistor is <0.5 µH.

[0043] According to an embodiment of the present disclosure, the silicon carbide has high electrical insulation and dielectric strength, which can improve the insulation performance of the grounding resistor and reduce the risk of grounding failure. Moreover, the silicon carbide has high high-frequency characteristics, which can reduce the high-frequency noise and electromagnetic interference in the rail train under high-frequency working conditions.

[0044] According to an embodiment of the present disclosure, a larger inductance value will introduce a larger impedance in a high-frequency signal, resulting in that the high-frequency signal cannot be effectively grounded, thereby generating common-mode interference in the electrical system.

[0045] According to an embodiment of the present disclosure, by setting the inductance parameter of the grounding resistor to be <0.5 µH, the high-frequency common-mode interference voltage can be minimized.

[0046] Figure 4 A structural schematic diagram of a rail train according to another embodiment of the present disclosure is schematically shown.

[0047] As shown in Figure 4 The rail train further includes an auxiliary inverter 114 and a high-voltage axle grounding end 160. The electrical transmission path between the high-voltage return grounding platform 111 and the high-voltage axle grounding end 160, the electrical transmission path between the high-voltage return grounding platform 111 and the traction inverter 113, and the electrical transmission path between the high-voltage return grounding platform 111 and the auxiliary inverter 114 are all equal.

[0048] According to an embodiment of the present disclosure, the installation positions of the traction inverter 113 and the auxiliary inverter 114 can be determined based on the marshalling form of the rail train. For example, in the case that the marshalling form of the rail train is four motored and two trailed, the traction inverter 113 can be installed on the four middle motor cars to ensure the efficiency of power transmission and the stability of vehicle operation. The auxiliary inverter 114 can be installed on the remaining two trailer cars. In the case that the marshalling form of the rail train is three motored and one trailed, the traction inverter 113 should be installed on the two middle motor cars and the head motor car, and the auxiliary inverter 114 can be installed on the remaining one trailer car.

[0049] According to an embodiment of the present disclosure, after determining the installation positions of the traction inverter 113 and the auxiliary inverter 114, the high-voltage return ground platform 111 can be arranged at the first end of the vehicle body 110, and the low-voltage return ground platform 112 can be arranged at the second end of the vehicle body 110, i.e., the positions of the high-voltage return ground platform 111 and the low-voltage return ground platform 112 are determined so that the electrical transmission paths between the high-voltage return ground platform 111 and the high-voltage axle ground end, between the high-voltage return ground platform 111 and the traction inverter 113, and between the high-voltage return ground platform 111 and the auxiliary inverter 114 are all equal, so as to minimize the inductance of the electrical transmission paths, reduce the voltage drop and electromagnetic interference caused by the inductance.

[0050] As shown in Figure 4 The rail train further includes a low-voltage axle ground end 170, a direct-current load 115, and an alternating-current load 116. The low-voltage axle ground end 170 is connected to the low-voltage return ground platform 112. The direct-current load 115 and the alternating-current load 116 are both connected to the low-voltage return ground platform 112.

[0051] According to an embodiment of the present disclosure, the direct-current load 115 can include a control unit in the rail train. The alternating-current load 116 can include an air conditioner, a heater, a lighting device, and the like in the rail train. The connection between the direct-current load 115 and the low-voltage return ground platform 112, and the connection between the alternating-current load 116 and the low-voltage return ground platform 112 can be achieved through cables, wiring terminals, or other electrical connection components.

[0052] According to an embodiment of the present disclosure, the capacity of the terminal grounding device is configured to be determined based on the return parameters between the high-voltage return ground platform 111 and the traction inverter 113, and the return parameters between the high-voltage return ground platform 111 and the auxiliary inverter 114.

[0053] According to an embodiment of the present disclosure, the return parameters can include current, voltage, and frequency, which can be measured based on an ammeter, a voltmeter, and a frequency meter, respectively.

[0054] According to an embodiment of the present disclosure, determining the capacity of the terminal grounding device based on the return parameters between the high-voltage return ground platform 111 and the traction inverter 113, and the return parameters between the high-voltage return ground platform 111 and the auxiliary inverter 114 can ensure that the terminal grounding device can accurately match the actual demand of the grounding system, thereby improving the grounding efficiency and the overall performance of the grounding system.

[0055] According to an embodiment of the present disclosure, the ratio of the capacity of the high-voltage axle ground end 160 to the capacity of the terminal grounding device is configured to be 1:2-1:3. For example, the capacity of the terminal grounding device can be 200A, and the capacity of the high-voltage axle ground end 160 can be 100A.

[0056] According to an embodiment of the present disclosure, the high-voltage axle grounding end 160 can provide a grounding path for the high-voltage system of the rail train, ensuring that in the event of a fault in the circuit in the high-voltage system, the fault current can safely flow to the ground. For example, the traction inverter 113 can be connected to the high-voltage axle grounding end 160 through the high-voltage return grounding platform 111, and in the event of insulation damage to the traction inverter 113, the fault current can safely flow to the ground.

[0057] According to an embodiment of the present disclosure, the ratio of the capacity of the low-voltage axle grounding end 170 to the capacity of the terminal grounding device is configured to be 1:4-1:5. For example, the capacity of the terminal grounding device can be 200A, and the capacity of the low-voltage axle grounding end 170 can be 50A.

[0058] According to an embodiment of the present disclosure, the low-voltage axle grounding end 170 can provide a grounding path for the low-voltage system of the rail train, ensuring that in the event of a fault in the circuit in the low-voltage system, the fault current can safely flow to the ground. For example, the alternating current load 116 can be connected to the low-voltage axle grounding end 170 through the low-voltage return grounding platform 112, and in the event of a short circuit or overload of the alternating current load 116, the fault current safely flows to the ground.

[0059] According to an embodiment of the present disclosure, based on the proportional relationship between the capacity of the high-voltage axle grounding end 160 and the capacity of the terminal grounding device, and the proportional relationship between the capacity of the low-voltage axle grounding end 170 and the capacity of the terminal grounding device, the capacity balance of each part of the grounding system can be ensured, which is conducive to evenly distributing the grounding current in the entire electrical system, optimizing the distribution of current between the axle end grounding device and the terminal grounding device, reducing the dependence on a single grounding point, and improving the stability of the entire electrical system.

[0060] According to an embodiment of the present disclosure, the wire between the high-voltage return grounding platform 111 and the traction inverter 113 is a return line, and the wire between the high-voltage return grounding platform 111 and the auxiliary inverter 114 is a return line, as shown by the dashed line in FIG. 1. Figure 4

[0061] According to an embodiment of the present disclosure, the material of the return line can be a metal material with high electrical conductivity and high mechanical strength, such as copper and aluminum.

[0062] According to an embodiment of the present disclosure, the wire between the low-voltage return grounding platform 112 and the auxiliary inverter 114 is a load connection line, the wire between the low-voltage return grounding platform 112 and the direct current load 115 is a load connection line, and the wire between the low-voltage return grounding platform 112 and the alternating current load 116 is a load connection line, as shown by the solid line in FIG. 1. Figure 4

[0063] ​​According to embodiments of the present disclosure, the load connection line can be used to provide an electrical transmission path from the negative pole of the power supply to the load negative pole.

[0064] According to embodiments of the present disclosure, based on the design of the return line and the load connection line, clear electrical return paths can be provided for high-voltage systems and low-voltage systems, which helps to improve the stability and reliability of the rail train. Moreover, the arrangement of the return line and the load connection line helps to optimize the distribution of current in the rail train, reduce hot spots and current congestion, and reduce losses.

[0065] The above describes embodiments of the present disclosure. However, these embodiments are only for illustrative purposes, and are not intended to limit the scope of the present disclosure. Although each embodiment is described above separately, this does not mean that the measures in each embodiment cannot be advantageously used in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A rail train comprising: a high-voltage return-flow grounding platform, a low-voltage return-flow grounding platform, a traction inverter and an auxiliary inverter arranged in a car body; and a traction motor and a high-voltage axle grounding end; wherein the high-voltage return-flow grounding platform is arranged at a first end of the car body, and the low-voltage return-flow grounding platform is arranged at a second end of the car body, so that high voltage and low voltage are isolated; the distance between the first end and the second end is > 10 m, the electrical transmission path between the high-voltage return-flow grounding platform and the high-voltage axle grounding end, the electrical transmission path between the high-voltage return-flow grounding platform and the traction inverter, and the electrical transmission path between the high-voltage return-flow grounding platform and the auxiliary inverter are all equal; the shell of the traction inverter and the shell of the traction motor are directly connected to shorten the electrical transmission path between the traction inverter and the traction motor.

2. The railcar of claim 1, further comprising: a grounding resistor and a terminal grounding device, the grounding resistor is arranged between the car body and the terminal grounding device to shorten the electrical transmission path between the car body, the grounding resistor and the terminal grounding device.

3. The railcar of claim 2, wherein, The material of the grounding resistor includes silicon carbide, and the inductance parameter of the grounding resistor is < 0.5 µH.

4. The railcar of claim 2, wherein, The capacity of the terminal grounding device is configured based on the return-flow parameters between the high-voltage return-flow grounding platform and the traction inverter, and the return-flow parameters between the high-voltage return-flow grounding platform and the auxiliary inverter.

5. The railcar of claim 2, wherein, The ratio of the capacity of the high-voltage axle grounding end to the capacity of the terminal grounding device is configured to be 1:2-1:

3.

6. The railcar of claim 5, wherein, The wire between the high-voltage return-flow grounding platform and the traction inverter is a return-flow wire, and the wire between the high-voltage return-flow grounding platform and the auxiliary inverter is a return-flow wire.

7. The railcar of claim 1, further comprising: a low-voltage axle grounding end, a direct-current load and an alternating-current load; wherein the low-voltage axle grounding end is connected to the low-voltage return-flow grounding platform; the direct-current load and the alternating-current load are both connected to the low-voltage return-flow grounding platform.

8. The railcar of claim 7, wherein, The ratio of the capacity of the low-voltage axle grounding end to the capacity of the terminal grounding device is configured to be 1:4-1:

5.

9. The railcar of claim 7, wherein, The wire between the low-voltage return-flow grounding platform and the auxiliary inverter is a load connection wire, the wire between the low-voltage return-flow grounding platform and the direct-current load is a load connection wire, and the wire between the low-voltage return-flow grounding platform and the alternating-current load is a load connection wire.

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