A protection device and method for an electric locomotive and an electric locomotive

Abstract

This application discloses a protection device, method, and electric locomotive for electric locomotives, belonging to the field of rail transit technology. The device includes: a permanent magnet traction motor, a traction converter, a traction control unit, three sets of contactors connected in series, and controllable fuses, respectively connected to the three-phase cable between the traction converter and the permanent magnet traction motor. The fuse control unit controls the on / off state of the three controllable fuses and, upon receiving a first control command from the traction control unit, controls the three controllable fuses to turn off, thereby disconnecting the permanent magnet traction motor and the traction converter. The first control command indicates that the traction control unit sends a turn-off command to the three contactors, without receiving feedback contact action information from N contactors; N≥2. This device can provide more reliable protection for the electric locomotive when a fault occurs, and prevent further expansion and aggravation of the fault.

Description

Technical Field

[0001] This invention relates to the field of rail transit technology, and in particular to a protection device and method for an electric locomotive, as well as an electric locomotive. Background Technology

[0002] Permanent magnet traction motors are widely used in electric locomotives due to their advantages such as high efficiency, light weight, and low operating noise. However, since the rotor of a permanent magnet traction motor is energized by permanent magnets, when a permanent magnet traction motor malfunctions, problems such as large torque pulsation, no-load back electromotive force, and two-phase short circuits or grounding caused by the propagation of inter-turn short circuits can occur, posing a significant risk to the safe and stable operation of the electric locomotive.

[0003] In existing technology, to ensure the safe and stable operation of electric locomotives, a contactor is typically connected to each of the three-phase cables of the traction converter and the permanent magnet traction motor. When a fault is detected in the electric locomotive, the contactor is shut off to disconnect the connection between the traction converter and the permanent magnet traction motor, preventing further spread and aggravation of the fault, thus protecting the electric locomotive. However, during long-term use, contactors may fail due to factors such as loss of elasticity of internal springs, jamming of the actuating mechanism, mechanical wear, contact aging, and environmental factors. This means that when a fault occurs in the electric locomotive, the contactor may fail to shut off in time, failing to achieve the purpose of protecting the locomotive. Currently, there is no effective solution to this technical problem. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a protection device, method, and a locomotive for electric locomotives, so as to provide more reliable protection for the electric locomotive when a fault occurs and to prevent the fault from further escalating and aggravating. The specific solution is as follows: To address the aforementioned technical problems, the present invention provides a protection device for electric locomotives, comprising: Permanent magnet traction motors are used to provide power to electric locomotives; A traction converter is used to provide three-phase AC power to the permanent magnet traction motor; Three sets of contactors and controllable fuses connected in series are respectively connected to the three-phase cable between the traction converter and the permanent magnet traction motor to isolate the permanent magnet traction motor and the traction converter. The traction control unit is used to control the on / off state of the three contactors; The fuse control unit is used to control the on / off state of three controllable fuses, and upon receiving a first control command from the traction control unit, controls the three controllable fuses to turn off, thereby disconnecting the permanent magnet traction motor and the traction converter; the first control command indicates that the traction control unit sends a turn-off command to the three contactors, but has not received a command from N contactors to provide feedback on contact action information; N≥2.

[0005] Preferred options also include: Two current sensors are connected to any two phases of the cable between the three controllable fuses and the permanent magnet traction motor, respectively, to detect the current in the connecting cables.

[0006] Preferably, the traction control unit and the fuse control unit establish a communication connection via a hardwire.

[0007] Preferably, the traction control unit and the fuse control unit establish a communication connection via optical fiber or a controller area network.

[0008] To address the aforementioned technical problems, the present invention also provides an electric locomotive, including a protection device for an electric locomotive as disclosed above.

[0009] To address the aforementioned technical problems, the present invention also provides a protection method for electric locomotives, applied to the traction control unit in the aforementioned protection device for electric locomotives, comprising: Real-time monitoring of the operating status of electric locomotives; When a fault is detected in the electric locomotive, a shutdown command is sent to the three contactors; If no contact action information is received from N contactors, a first control command is sent to the fuse control unit to disconnect the permanent magnet traction motor and the traction converter using three controllable fuses; N≥2.

[0010] Preferred options also include: The circuit module in the traction converter used to convert DC power to AC power is identified as an inverter module. If the operating current of the inverter module is greater than a preset current and / or the operating voltage of the inverter module is greater than a preset voltage and / or the temperature value of the inverter module is greater than a preset temperature value and / or the speed of the permanent magnet traction motor is greater than a preset speed and / or the difference between the maximum torque and the minimum torque of the permanent magnet traction motor is greater than a preset torque, then the electric locomotive is determined to have malfunctioned.

[0011] Preferably, when two current sensors are connected to any two phases of the cable between the three controllable fuses and the permanent magnet traction motor, after sending the shutdown command to the three contactors, the method further includes: If contact action information is received from N contactors, it is determined whether the detection current of the two current sensors is less than the preset threshold. If not, the fuse control unit sends a second control command to the three controllable fuses to disconnect the line connection between the permanent magnet traction motor and the traction converter.

[0012] Preferably, after determining whether the detected currents of the two current sensors are both less than a preset threshold, the method further includes: If so, the three contactors are determined to be normally disconnected, and the step of real-time detection of the operating status of the electric locomotive continues.

[0013] Preferably, the preset threshold is set based on a first current and a second current; the first current is the current corresponding to a two-phase short circuit fault in the three contactors, and the second current is the current corresponding to a current backflow in the electric locomotive.

[0014] Beneficial Effects: Compared to existing technologies, the electric locomotive protection device provided by this invention, in addition to connecting contactors to the three-phase cables between the permanent magnet traction motor and the traction converter, also connects controllable fuses to the three-phase cables between the permanent magnet traction motor and the traction converter. When the electric locomotive malfunctions, besides using the traction control unit to disconnect the line connection between the permanent magnet traction motor and the traction converter, the fuse control unit can also disconnect the connection between the permanent magnet traction motor and the traction converter by blowing the controllable fuse upon receiving the first control command sent by the traction control unit. This completely eliminates the feedback path of the back electromotive force generated by the permanent magnet traction motor when the electric locomotive malfunctions, effectively protecting the devices and power modules on the connection lines between the permanent magnet traction motor and the traction converter, and thereby eliminating the safety hazards that exist when the contactors fail to shut off in time. Therefore, this protection device can provide more reliable protection for the electric locomotive when a malfunction occurs, and prevent the further expansion and aggravation of the malfunction.

[0015] Correspondingly, the electric locomotive protection method and electric locomotive provided by the present invention also have the above-mentioned beneficial effects. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present 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 only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 This is a structural diagram of the protection device for electric locomotives in the prior art; Figure 2 A structural diagram of a protection device for an electric locomotive provided in an embodiment of the present invention; Figure 3 A structural diagram of another protection device for an electric locomotive provided in an embodiment of the present invention; Figure 4 A flowchart illustrating a protection method for an electric locomotive provided in an embodiment of the present invention; Figure 5 A flowchart illustrating another protection method for electric locomotives provided in an embodiment of the present invention. Detailed Implementation

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

[0019] To enable those skilled in the art to more clearly understand the implementation principle of this invention, the structure of a protection device for electric locomotives in the prior art is first described here. Please refer to... Figure 1 , Figure 1 This is a structural diagram of the protection device for electric locomotives in the prior art. As... Figure 1 As shown, in the prior art, in order to ensure the safe and stable operation of electric locomotives, contactors Ka, Kb and Kc are usually connected to the three-phase cables of the traction converter and the permanent magnet traction motor M respectively. When a fault is detected in the electric locomotive, the connection between the traction converter and the permanent magnet traction motor M is disconnected by turning off contactors Ka, Kb and Kc, thereby preventing the further spread and aggravation of the fault.

[0020] When an electric locomotive operates at high speed, the back electromotive force (EMF) it generates is high, typically exceeding the rated voltage of the intermediate DC link. If the inverter module in the traction converter malfunctions and the contactor experiences a jamming problem, the back EMF generated by the permanent magnet traction motor will be injected back into the locomotive's DC link through the inverter module, damaging components and power switches in the DC link. Furthermore, if the contactor itself malfunctions, causing a phase-to-phase short circuit, the connection between the traction converter and the permanent magnet traction motor cannot be disconnected in time. This will also increase the torque pulsation of the permanent magnet traction motor, further exacerbating the locomotive's malfunction.

[0021] To address the aforementioned technical problems, this invention provides a novel protective device for electric locomotives. Please refer to [link / reference]. Figure 2 , Figure 2 This is a structural diagram of a protection device for an electric locomotive provided in an embodiment of the present invention. The device includes: The permanent magnet traction motor M is used to provide power to the electric locomotive; Traction converter 10 is used to supply three-phase AC power to permanent magnet traction motor M; Three sets of contactors Ka, Kb, Kc connected in series and controllable fuses Qa, Qb, Qc are connected to the three-phase cable between the traction converter 10 and the permanent magnet traction motor M, respectively, to isolate the permanent magnet traction motor M and the traction converter 10. The traction control unit (TCU) is used to control the on / off state of three contactors, Ka, Kb, and Kc. The fuse control unit (FCU) controls the on / off states of three controllable fuses Qa, Qb, and Qc. Upon receiving the first control command from the traction control unit (TCU), it controls the three controllable fuses to turn off, thereby disconnecting the permanent magnet traction motor M from the traction converter 10. The first control command is used by the traction control unit (TCU) to send a turn-off command to the three contactors, without receiving feedback contact action information from N contactors; N≥2.

[0022] In the protection device for electric locomotives provided by this invention, in addition to connecting three contactors Ka, Kb, and Kc to the three-phase cable between the traction converter 10 and the permanent magnet traction motor M, three controllable fuses Qa, Qb, and Qc are also connected to the three-phase cable between the traction converter 10 and the permanent magnet traction motor M. The on / off states of the three contactors Ka, Kb, and Kc are controlled by the traction control unit, while the on / off states of the three controllable fuses Qa, Qb, and Qc are controlled by the fuse control unit (FCU).

[0023] When the traction control unit (TCU) detects a fault in the electric locomotive, it sends a shutdown command to three contactors Ka, Kb, and Kc to disconnect the circuit between the permanent magnet traction motor M and the traction converter 10. Under normal circumstances, if the TCU receives contact action information from the three contactors Ka, Kb, and Kc after sending the shutdown command, it indicates that all three contactors are open, and the circuit between the permanent magnet traction motor M and the traction converter 10 is open.

[0024] If the traction control unit (TCU) does not receive contact action information from two or more contactors, it indicates that at least two of the three contactors Ka, Kb, and Kc have failed to close in time, and the connection between the permanent magnet traction motor M and the traction converter 10 has not been disconnected in time. In this case, the TCU will send a first control command to the fuse control unit (FCU). When the FCU receives the first control command from the TCU, it will control the three controllable fuses Qa, Qb, and Qc to blow, thereby disconnecting the connection between the permanent magnet traction motor M and the traction converter 10.

[0025] Clearly, this configuration effectively uses controllable fuses to proactively disconnect the circuit between the permanent magnet traction motor M and the traction converter 10 when the contactor fails to shut off in time. This completely cuts off the feedback path of the back electromotive force generated by the permanent magnet traction motor M, providing a higher safety margin for the electric locomotive. Furthermore, in this application, the three controllable fuses Qa, Qb, and Qc can quickly disconnect the connection between the permanent magnet traction motor M and the traction converter 10 in the early stages of a locomotive malfunction. This effectively protects the components and power modules in the intermediate DC link inside the electric locomotive, significantly improving its safety performance.

[0026] Compared to existing technologies, the protection device for electric locomotives provided in this embodiment, in addition to connecting contactors to the three-phase cables between the permanent magnet traction motor and the traction converter, also connects controllable fuses to the three-phase cables between the permanent magnet traction motor and the traction converter. When the electric locomotive malfunctions, besides using the traction control unit to disconnect the line connection between the permanent magnet traction motor and the traction converter, the fuse control unit can also disconnect the connection between the permanent magnet traction motor and the traction converter by blowing the controllable fuse upon receiving the first control command sent by the traction control unit. This completely eliminates the feedback path of the back electromotive force generated by the permanent magnet traction motor when the electric locomotive malfunctions, effectively protecting the devices and power modules on the connection lines between the permanent magnet traction motor and the traction converter, and thereby eliminating the safety hazards that exist when the contactors fail to shut off in time. Therefore, this protection device can provide more reliable protection for the electric locomotive when a malfunction occurs, and prevent the further expansion and aggravation of the malfunction.

[0027] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. Please refer to [link / reference]. Figure 3 , Figure 3 This is a structural diagram of another protection device for an electric locomotive provided in an embodiment of the present invention. The protection device further includes: Two current sensors, A1 and B1, are connected to any two phases of the cable between the three controllable fuses Qa, Qb, Qc and the permanent magnet traction motor M, respectively, to detect the current in the connecting cables.

[0028] Understandably, when an electric locomotive malfunctions, the traction control unit (TCU) sends a shutdown command to the three contactors Ka, Kb, and Kc. Normally, if these three contactors shut off correctly, the three-phase connection cable between the permanent magnet traction motor M and the traction converter 10 will be disconnected. At this point, the current in each phase connection cable between the permanent magnet traction motor M and the traction converter 10 will be less than a preset threshold. If the current in any phase connection cable between the permanent magnet traction motor M and the traction converter 10 exceeds the preset threshold, it indicates that one of the three contactors Ka, Kb, and Kc is falsely disconnected, which could potentially exacerbate the locomotive malfunction.

[0029] In this embodiment, in order to enable the staff to more clearly know the real-time operating status of the electric locomotive after the traction control unit (TCU) sends the shut-off command to the three contactors Ka, Kb, and Kc, two current sensors A1 and B1 are connected to any two phase cables between the three controllable fuses Qa, Qb, and Qc and the permanent magnet traction motor M. The current sensors A1 and B1 are used to detect the current in any two phase cables between the three controllable fuses Qa, Qb, and Qc and the permanent magnet traction motor M in real time.

[0030] It should be noted that in this embodiment, to reduce the cost of the electric locomotive protection device, two current sensors A1 and B1 are connected to any two phases of the cable between the three controllable fuses Qa, Qb, and Qc and the permanent magnet traction motor M. This is because in practical applications, the current detection values ​​on two phases of the cable are usually sufficient to determine whether the three contactors Ka, Kb, and Kc are properly turned off. Of course, to increase the accuracy of current detection, a current sensor can be connected to each of the three phases of the cable between the three controllable fuses Qa, Qb, and Qc and the permanent magnet traction motor M.

[0031] Obviously, the operating status of an electric locomotive can be determined by the current detected by two current sensors through the technical solution provided in this embodiment.

[0032] Based on the above embodiments, this embodiment further explains and optimizes the technical solution, and the traction control unit TCU and the fuse control unit FCU establish a communication connection through a hard wire.

[0033] In this embodiment, in order to improve the stability and reliability of the traction control unit (TCU) and the fuse control unit (FCU) during communication, the traction control unit (TCU) and the fuse control unit (FCU) establish a communication connection through a hard wire.

[0034] In addition, in practical applications, the traction control unit (TCU) and the fuse control unit (FCU) can also establish communication connections via optical fiber or Controller Area Network (CAN).

[0035] Because optical fiber not only has strong resistance to electromagnetic interference, making it more suitable for the operating environment of electric locomotives, but also has the advantages of low loss, small size and light weight, this configuration makes it easier to lay optical fiber on electric locomotives.

[0036] Controller Area Networks (CLANs) are inexpensive to build and have a complete error correction mechanism. Therefore, when the Traction Control Unit (TCU) and the Fuse Control Unit (FCU) communicate using a CLAN, the overall reliability of the TCU and FCU during the communication process can be further improved.

[0037] Accordingly, embodiments of the present invention also provide an electric locomotive, including a protection device for an electric locomotive as disclosed above.

[0038] The electric locomotive provided in this embodiment of the invention has the beneficial effects of the aforementioned protective device for an electric locomotive.

[0039] Please see Figure 4 , Figure 4 A flowchart illustrating a protection method for an electric locomotive provided in an embodiment of the present invention. This method is applied to a traction control unit in the aforementioned protection device for an electric locomotive. The method includes: Step S11: Real-time monitoring of the operating status of the electric locomotive; Step S12: When a fault is detected in the electric locomotive, a shutdown command is sent to the three contactors; Step S13: If no contact action information is received from N contactors, a first control command is sent to the fuse control unit to disconnect the permanent magnet traction motor and the traction converter using three controllable fuses; N≥2.

[0040] This embodiment specifically describes the control logic of the traction control unit in the electric locomotive protection device. In the electric locomotive protection device, the traction control unit first monitors the operating status of the electric locomotive in real time. When the traction control unit detects a fault in the electric locomotive, in order to prevent the fault from further aggravating and spreading, the traction control unit sends a shutdown command to the three contactors.

[0041] If the traction control unit does not receive contact action information from N contactors, it indicates that at least two of the three contactors have failed to close in time. In this situation, the electric locomotive faces a significant safety hazard. At this point, the traction control unit will send a first control command to the fuse control unit. Upon receiving this command, the fuse control unit will send a shut-off command to the three controllable fuses, thereby breaking the connection between the permanent magnet traction motor and the traction converter.

[0042] It is easy to see that by using three controllable fuses to disconnect the circuit between the permanent magnet traction motor and the traction converter, the feedback path of the back electromotive force generated by the permanent magnet traction motor is completely eliminated. This provides more reliable protection for the electric locomotive and prevents the fault from further expanding and aggravating.

[0043] Clearly, the technical solution provided in this embodiment can provide more reliable protection for electric locomotives.

[0044] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation, the above protection method further includes: The circuit module in the traction converter used to convert DC to AC is identified as the inverter module. If the operating current of the inverter module is greater than the preset current and / or the operating voltage of the inverter module is greater than the preset voltage and / or the temperature value of the inverter module is greater than the preset temperature value and / or the speed of the permanent magnet traction motor is greater than the preset speed and / or the difference between the maximum torque and the minimum torque of the permanent magnet traction motor is greater than the preset torque, then the electric locomotive is determined to have malfunctioned.

[0045] This embodiment provides a method for diagnosing faults in electric locomotives. The determination of whether a fault has occurred in the electric locomotive is primarily based on assessing the operating status of the inverter circuit in the traction converter.

[0046] Specifically, the circuit module in the traction converter used to convert DC to AC power can be named the inverter module. If the operating current of the inverter module is detected to be greater than the preset current, it indicates that the inverter module has an overcurrent fault; if the operating voltage of the inverter module is detected to be greater than the preset voltage, it indicates that the inverter module has an overvoltage fault; if the temperature of the inverter module is detected to be greater than the preset temperature, it indicates that the inverter module has an overtemperature fault.

[0047] In addition, if the speed of the permanent magnet traction motor is detected to be greater than the preset speed, it indicates that the permanent magnet traction motor may have a risk of back electromotive force overvoltage, which will affect the safe operation of the electric locomotive. If the difference between the maximum torque and the minimum torque of the permanent magnet traction motor is detected to be greater than the preset torque, it indicates that the electric locomotive has a serious torque pulsation problem, which will seriously affect the safe and stable operation of the electric locomotive. In practical applications, if one or more of the above fault conditions occur, it can be determined that the electric locomotive has malfunctioned, and it is necessary to disconnect the line connection between the permanent magnet traction motor and the traction converter.

[0048] Obviously, the technical solution provided in this embodiment can be used to determine whether an electric locomotive has malfunctioned.

[0049] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. Please refer to [link / reference]. Figure 5 , Figure 5 This is a flowchart illustrating a protection method for an electric locomotive provided in an embodiment of the present invention. In a preferred embodiment, when two current sensors are connected to any two phases of the cable between the three controllable fuses and the permanent magnet traction motor, after sending a shutdown command to the three contactors, the method further includes: Step S14: If contact action information is received from N contactors, determine whether the detection current of the two current sensors is less than the preset threshold. Step S15: If not, send a second control command to the three controllable fuses through the fuse control unit to disconnect the line connection between the permanent magnet traction motor and the traction converter.

[0050] Please see Figure 3 The protection device of the electric locomotive shown has two current sensors connected to any two phases of the cable between the three controllable fuses and the permanent magnet traction motor. If the traction control unit sends a shut-off command to the three contactors, it receives contact action information from N contactors. To determine whether the three contactors have truly disconnected the line connection between the permanent magnet traction motor and the traction converter, it can further determine whether the detected current of the two current sensors is less than a preset threshold.

[0051] If the detected currents of the two current sensors are not both less than the preset threshold, it indicates that at least one of the current sensors has a detected current greater than or equal to the preset threshold, suggesting a "false shutdown" contactor or other special fault in the electric locomotive. In this case, the traction control unit can send a second control command to the fuse control unit. When the fuse control unit receives the second control command, it sends shutdown commands to the three controllable fuses, thereby disconnecting the circuit between the permanent magnet traction motor and the traction converter.

[0052] Please continue reading Figure 5 The above steps, after determining whether the detected currents of both current sensors are less than a preset threshold, also include: Step S16: If yes, then it is determined that the three contactors are normally disconnected, and the step of real-time detection of the operating status of the electric locomotive continues.

[0053] If the detected current of both current sensors is less than the preset threshold, it means that there is no "false shutdown" contactor, the three contactors are normally disconnected, and the connection line between the permanent magnet traction motor and the traction converter is in a disconnected state. In this case, step S11 can be continued: real-time detection of the operating status of the electric locomotive.

[0054] In a preferred embodiment, the preset threshold is set based on a first current and a second current; the first current is the current corresponding to a two-phase short circuit fault in the three contactors, and the second current is the current corresponding to a current backflow in the electric locomotive.

[0055] In this embodiment, the preset threshold is set based on a first current and a second current. The first current refers to the current corresponding to a two-phase short circuit in the three contactors, while the second current refers to the current corresponding to current recovery in the electric locomotive. Furthermore, the preset threshold is set based on the smaller of the first and second currents, which further ensures the accuracy and reliability of the determination result when the contactor is falsely turned off.

[0056] Clearly, the technical solution provided in this embodiment is equivalent to introducing a judgment mechanism of control command + feedback information + current detection into the electric locomotive, so as to ensure that the electric locomotive can more safely and reliably disconnect the line connection between the permanent magnet traction motor and the traction converter when a fault occurs. This eliminates the safety hazards that exist when relying solely on contactor feedback information to judge the line connection between the permanent magnet traction motor and the traction converter.

[0057] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0058] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0059] The present invention has provided a detailed description of a protection device and method for an electric locomotive, as well as an electric locomotive. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A protective device for an electric locomotive, characterized in that, include: Permanent magnet traction motors are used to provide power to electric locomotives; A traction converter is used to provide three-phase AC power to the permanent magnet traction motor; Three sets of contactors and controllable fuses connected in series are respectively connected to the three-phase cable between the traction converter and the permanent magnet traction motor to isolate the permanent magnet traction motor and the traction converter. The traction control unit is used to control the on / off state of the three contactors; The fuse control unit is used to control the on / off state of three controllable fuses, and upon receiving a first control command from the traction control unit, controls the three controllable fuses to turn off, thereby disconnecting the permanent magnet traction motor and the traction converter; the first control command indicates that the traction control unit sends a turn-off command to the three contactors, but has not received a command from N contactors to provide feedback on contact action information; N≥2.

2. The protection device for an electric locomotive according to claim 1, characterized in that, Also includes: Two current sensors are connected to any two phases of the cable between the three controllable fuses and the permanent magnet traction motor, respectively, to detect the current in the connecting cables.

3. The protection device for an electric locomotive according to claim 1, characterized in that, The traction control unit and the fuse control unit establish a communication connection via a hard wire.

4. The protection device for an electric locomotive according to claim 3, characterized in that, The traction control unit and the fuse control unit establish a communication connection via optical fiber or a controller area network.

5. An electric locomotive, characterized in that, Includes a protective device for an electric locomotive as described in any one of claims 1 to 4.

6. A protection method for an electric locomotive, characterized in that, A traction control unit applied in a protection device for an electric locomotive according to any one of claims 1 to 4, comprising: Real-time monitoring of the operating status of electric locomotives; When a fault is detected in the electric locomotive, a shutdown command is sent to the three contactors; If no contact action information is received from N contactors, a first control command is sent to the fuse control unit to disconnect the permanent magnet traction motor and the traction converter using three controllable fuses; N≥2.

7. The protection method for an electric locomotive according to claim 6, characterized in that, Also includes: The circuit module in the traction converter used to convert DC power to AC power is identified as an inverter module. If the operating current of the inverter module is greater than a preset current and / or the operating voltage of the inverter module is greater than a preset voltage and / or the temperature value of the inverter module is greater than a preset temperature value and / or the speed of the permanent magnet traction motor is greater than a preset speed and / or the difference between the maximum torque and the minimum torque of the permanent magnet traction motor is greater than a preset torque, then the electric locomotive is determined to have malfunctioned.

8. A protection method for an electric locomotive according to claim 6, characterized in that, When two current sensors are connected to any two phases of the cable between the three controllable fuses and the permanent magnet traction motor, after sending the shutdown command to the three contactors, the process further includes: If contact action information is received from N contactors, it is determined whether the detection current of the two current sensors is less than the preset threshold. If not, the fuse control unit sends a second control command to the three controllable fuses to disconnect the line connection between the permanent magnet traction motor and the traction converter.

9. A protection method for an electric locomotive according to claim 8, characterized in that, After determining whether the detected currents of the two current sensors are both less than a preset threshold, the method further includes: If so, the three contactors are determined to be normally disconnected, and the step of real-time detection of the operating status of the electric locomotive continues.

10. A protection method for an electric locomotive according to claim 8, characterized in that, The preset threshold is set based on a first current and a second current; the first current is the current corresponding to a two-phase short circuit fault in the three contactors, and the second current is the current corresponding to a current backflow in the electric locomotive.

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