Short-circuit fault detection method of permanent magnet traction system and related equipment

Abstract

The invention provides a short-circuit fault detection method of a permanent magnet traction system and related equipment, and the method comprises the steps: 1, collecting an electric signal of an output side of an inverter, and decomposing the electric signal to obtain a positive-sequence electric signal and a negative-sequence electric signal; step 2, calculating a detection value for performing short-circuit fault detection; 3, obtaining an original short-circuit fault detection result according to a difference value between the initial detection threshold value and the detection value; 4, if the original short-circuit fault detection result shows that the short-circuit fault occurs, controlling the three-level isolation controller to be closed, returning to execute the above steps, and if the new short-circuit fault detection result is the same as the original short-circuit fault detection result, determining the original short-circuit fault detection result as a final short-circuit fault detection result; otherwise, updating the initial detection threshold value according to a preset step, taking the middle detection threshold value as the initial detection threshold value in the step 3, and returning to execute the step 3. According to the invention, the accuracy of short-circuit fault detection can be improved.

Description

Technical Field

[0001] The present invention relates to a permanent magnet motor traction system, and specifically to a short-circuit fault detection method and related equipment for the permanent magnet traction system. Background Art

[0002] As one of the important components for energy conversion and power transmission in the traction drive system of rail transit vehicles, the normal operation of the traction motor directly affects the traction performance, acceleration capability and operation capability of the EMU, and is also one of the important factors to ensure the safe operation of the EMU. Among them, the permanent magnet synchronous traction motor has advantages over the asynchronous traction motor in terms of high efficiency and energy saving, high power density and high power factor. Its application in the rail transit industry at home and abroad has gradually expanded from the subway field to the high-speed EMU field.

[0003] There are many methods for detecting traction motor short-circuit faults, mainly based on electrical signal analysis (current and voltage signal analysis), model-based methods (state observer method, parameter identification method), artificial intelligence-based methods (neural network method, support vector machine method, fuzzy logic method, etc.) and methods based on other physical quantities (vibration signal analysis method, temperature monitoring method). At present, the rail transit industry mostly realizes online detection of traction motor inter-turn short-circuit faults based on the results of current signal analysis. The detection principle is that when an inter-turn short circuit occurs in the traction motor, the symmetry of the three-phase current will be destroyed, generating a negative sequence current component. By detecting and analyzing the magnitude of the negative sequence current, it can be determined whether the motor has an inter-turn short circuit fault.

[0004] However, the traditional method only relies on fixed thresholds to judge inter-turn short-circuit faults, which has limitations. In actual operation, the threshold cannot be updated and corrected in real time, affecting the accuracy of short-circuit fault detection. In addition, the influence of the inverter itself on fault diagnosis (such as reverse power influence and current waveform distortion) is not considered, which can easily lead to misjudgment and reduce the accuracy of short-circuit fault detection. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a short-circuit fault detection method and related equipment for a permanent magnet traction system, so as to improve the accuracy of short-circuit fault detection.

[0006] In a first aspect, the present invention provides a short-circuit fault detection method for a permanent magnet traction system, wherein the permanent magnet traction system comprises a permanent magnet synchronous motor and an inverter connected to the permanent magnet synchronous motor in three phases, and a three-level isolation controller is connected between the permanent magnet synchronous motor and the inverter. The method comprises the following steps:

[0007] Step 1, collecting the electrical signal at the output side of the inverter, and decomposing the electrical signal to obtain a positive sequence electrical signal and a negative sequence electrical signal; the electrical signal is a three-phase current signal or a three-phase voltage signal;

[0008] Step 2, calculating a detection value for short-circuit fault detection according to the positive-sequence electrical signal and the negative-sequence electrical signal;

[0009] Step 3, obtaining an original short-circuit fault detection result according to the difference between the initial detection threshold and the detection value; the initial detection threshold is determined by the positive-sequence electrical signal and the negative-sequence electrical signal of the permanent magnet traction system under normal operating conditions, and the original short-circuit fault detection result is whether a short-circuit fault occurs or not;

[0010] Step 4: If the original short-circuit fault detection result is that a short-circuit fault occurs, the three-level isolation controller is controlled to close, and the process returns to step 1 to step 3 to obtain a new short-circuit fault detection result. If the new short-circuit fault detection result is the same as the original short-circuit fault detection result, the original short-circuit fault detection result is determined as the final short-circuit fault detection result; otherwise, the initial detection threshold is updated according to a preset step to obtain an intermediate detection threshold, and the intermediate detection threshold is used as the initial detection threshold in step 3, and the process returns to step 3.

[0011] Optionally, decomposing the electrical signal to obtain a positive-sequence electrical signal and a negative-sequence electrical signal includes:

[0012] When the electrical signal is a three-phase current signal, the calculation formula is

[0013]

[0014] in, Represents the positive sequence current signal, Indicates the inverter output U-phase current, α indicates U-phase, α=e j120 =e -j240 , Indicates the inverter output V phase current, Indicates the inverter output W-phase current, α 2 =e j240 =e -j120 , Represents the negative sequence current signal, a, b, c represent the three phases U, V, W on the inverter output side;

[0015] When the electrical signal is a three-phase voltage signal, the calculation formula is

[0016]

[0017] in, Represents the positive sequence voltage signal, Indicates the inverter output UV line voltage, Indicates the inverter output VW line voltage, Indicates the inverter output UW line voltage.

[0018] Optionally, calculating a detection value for short-circuit fault detection according to the positive-sequence electrical signal and the negative-sequence electrical signal includes:

[0019] When the electrical signal is a three-phase current signal, the calculation formula is

[0020]

[0021] or

[0022]

[0023] or

[0024]

[0025] Get the detection value J K ; Wherein, F(·) represents the negative sequence current threshold which is linearly related to the speed, and V represents the speed of the permanent magnet synchronous motor;

[0026] When the electrical signal is a three-phase voltage signal, the calculation formula is

[0027]

[0028] or

[0029]

[0030] or

[0031]

[0032] Get the detection value J K .

[0033] Optionally, the calculation method of the initial detection threshold is the same as the calculation method of the detection value, which uses the positive sequence electrical signal and the negative sequence electrical signal of the permanent magnet traction system under normal operating conditions.

[0034] Optionally, an original short-circuit fault detection result is obtained according to a difference between an initial detection threshold and a detection value, including:

[0035] If the difference is greater than zero, the original short-circuit fault detection result is determined to be that a short-circuit fault has occurred; otherwise, the original short-circuit fault detection result is determined to be that no short-circuit fault has occurred.

[0036] Optionally, the initial detection threshold is updated according to a preset step to obtain an intermediate detection threshold, including:

[0037] By calculating the formula

[0038]

[0039] Get the intermediate detection threshold in, Represents the initial detection threshold.

[0040] Optionally, before decomposing the electrical signal, the short circuit fault detection method further includes:

[0041] For any two phase electrical signals in the electrical signal, respectively, based on the two phase electrical signals, calculate a theoretical value of the third phase electrical signal;

[0042] If the error between the theoretical value of the third phase electrical signal and the actual value of the collected third phase electrical signal is greater than a preset threshold, the third phase electrical signal is recollected until the error is less than or equal to the preset threshold.

[0043] In a second aspect, the present invention provides a short-circuit fault detection device for a permanent magnet traction system, comprising:

[0044] A feature extraction module is used to collect the electrical signal at the output side of the inverter and decompose the electrical signal to obtain a positive sequence electrical signal and a negative sequence electrical signal; the electrical signal is a three-phase current signal or a three-phase voltage signal;

[0045] A detection calculation module, used to calculate a detection value for short-circuit fault detection based on a positive-sequence electrical signal and a negative-sequence electrical signal;

[0046] A preliminary detection module is used to obtain an original short-circuit fault detection result according to the difference between the initial detection threshold and the detection value; the initial detection threshold is determined by the positive sequence electrical signal and the negative sequence electrical signal of the permanent magnet traction system under normal operating conditions, and the original short-circuit fault detection result is the occurrence of a short-circuit fault or the absence of a short-circuit fault;

[0047] The re-detection module is used to control the three-level isolation controller to close if the original short-circuit fault detection result is a short-circuit fault, return the execution feature extraction module to the preliminary detection module, and obtain a new short-circuit fault detection result. If the new short-circuit fault detection result is the same as the original short-circuit fault detection result, the original short-circuit fault detection result is determined as the final short-circuit fault detection result; otherwise, the initial detection threshold is updated according to the preset step to obtain the intermediate detection threshold, and the intermediate detection threshold is used as the initial detection threshold in the preliminary detection module, and the preliminary detection module is returned to execute.

[0048] In a third aspect, the present invention provides a terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the above method is implemented when the processor executes the computer program.

[0049] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program implements the above method when executed by a processor.

[0050] The beneficial effects of the present invention are:

[0051] The short-circuit fault detection method provided by the present invention, when the original short-circuit fault detection result is that a short-circuit fault occurs, controls the three-level isolation controller to close, disconnects the inverter, re-collects the electrical signal and performs detection to obtain a new short-circuit fault detection result; when the original short-circuit fault detection result and the new short-circuit fault detection result are the same, the original short-circuit fault detection result is determined as the final short-circuit fault detection result, which can effectively avoid the interference of the inverter on the short-circuit fault detection and improve the accuracy of the short-circuit fault detection; when the original short-circuit fault detection result and the new short-circuit fault detection result are different, the initial detection threshold can be updated, and the threshold can be updated and corrected in real time, which is conducive to improving the accuracy of the short-circuit fault detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a schematic structural diagram of a permanent magnet traction system in one embodiment of the present application;

[0053] Figure 2 This is a flow chart of a short circuit fault detection method in one embodiment of the present application;

[0054] Figure 3 This is a schematic diagram of the structure of a short-circuit fault detection device in one embodiment of the present application;

[0055] Figure 4 This is a schematic diagram of the structure of a terminal device in one embodiment of the present application. DETAILED DESCRIPTION

[0056] In response to the problem of low accuracy of traditional short-circuit fault detection methods, the present invention provides a short-circuit fault detection method and related equipment for a permanent magnet traction system, wherein, when the original short-circuit fault detection result is a short-circuit fault, the short-circuit fault detection method controls the three-level isolation controller to close, disconnects the inverter, re-collects the electrical signal and performs detection to obtain a new short-circuit fault detection result; when the original short-circuit fault detection result and the new short-circuit fault detection result are the same, the original short-circuit fault detection result is determined as the final short-circuit fault detection result, which can effectively avoid the interference of the inverter on the short-circuit fault detection and improve the accuracy of the short-circuit fault detection; when the original short-circuit fault detection result and the new short-circuit fault detection result are different, the initial detection threshold can be updated, and the threshold can be updated and corrected in real time, which is beneficial to improving the accuracy of the short-circuit fault detection.

[0057] To facilitate understanding, the structural principle of the permanent magnet traction system in the embodiment of the present invention is described below.

[0058] like Figure 1As shown, the permanent magnet traction system includes a permanent magnet synchronous motor 101 and an inverter 102 connected to the permanent magnet synchronous motor 101 in three phases, and a three-level isolation controller 103 is connected between the permanent magnet synchronous motor 101 and the inverter 102 .

[0059] The permanent magnet synchronous motor 101 is used as a driving motor to drive electric vehicles or rail transit, and uses permanent magnets to generate magnetic fields, so no current-excited windings are required. The main components of the permanent magnet synchronous motor 101 include a stator, a rotor, and a bearing.

[0060] The inverter 102 is a key device connecting the permanent magnet synchronous motor 101 and the power supply. It is responsible for converting the DC power supply or AC power supply into three-phase AC power suitable for the operation of the permanent magnet synchronous motor 101 and controlling the motor's operating parameters such as speed and torque.

[0061] The three-level isolation controller 103 is used to ensure electrical isolation, protection and control between the permanent magnet synchronous motor 101 and the inverter 102, in order to ensure the safety and reliability of the motor drive system.

[0062] The short-circuit fault detection method provided by the present invention is described below.

[0063] like Figure 2 As shown, the short circuit fault detection method includes steps 1 to 4.

[0064] Step 1: collect the electrical signal at the output side of the inverter, and decompose the electrical signal to obtain a positive sequence electrical signal and a negative sequence electrical signal.

[0065] In an embodiment of the present invention, the electrical signal is a three-phase current signal or a three-phase voltage signal. Correspondingly, the electrical signal can be collected by a current sensor or a voltage sensor.

[0066] In order to avoid detection errors caused by abnormal sampling of a single sensor signal, before decomposing the electrical signal, the short-circuit fault detection method provided by the present invention will also verify the collected electrical signal, and the verification process includes steps I to II.

[0067] Step I: for any two-phase electrical signals in the electrical signal, respectively, based on the two-phase electrical signals, calculate the theoretical value of the third-phase electrical signal.

[0068] For example, the theoretical values ​​of the electrical signals are denoted as a(t), b(t), and c(t), and the phase difference between the electrical signals of each phase is 120 degrees. Then the theoretical values ​​of the electrical signals of each phase are a(t)=A cos(ωt), b(t)=A cos(ωt-120°), and c(t)=A cos(ωt+120°).

[0069] Step II: if the error between the theoretical value of the third phase electrical signal and the actual value of the collected third phase electrical signal is greater than a preset threshold, the third phase electrical signal is collected again until the error is less than or equal to the preset threshold.

[0070] If the error is greater than a preset threshold (such as 0.05), it means that the sensor collecting the third-phase electrical signal is abnormal and needs to be re-collected. If the error is greater than the preset threshold for multiple times, a new sensor is replaced to collect the third-phase electrical signal.

[0071] The following describes the process of decomposing the electrical signal to obtain the positive sequence electrical signal and the negative sequence electrical signal.

[0072] According to the different types of collected electrical signals, it is divided into case A and case B.

[0073] In case A, when the electrical signal is a three-phase current signal, the calculation formula is

[0074]

[0075] in, Represents the positive sequence current signal, Indicates the inverter output U-phase current, α indicates U-phase, α=e j120 =e -j240 , Indicates the inverter output V phase current, Indicates the inverter output W-phase current, α 2 =e j240 =e -j120 , Represents the negative sequence current signal, a, b, c represent the three phases U, V, W on the inverter output side;

[0076] Case B, when the electrical signal is a three-phase voltage signal, the calculation formula is

[0077]

[0078] in, Represents the positive sequence voltage signal, Indicates the inverter output UV line voltage, Indicates the inverter output VW line voltage, Indicates the inverter output UW line voltage.

[0079] Step 2: Calculate a detection value for short-circuit fault detection based on the positive-sequence electrical signal and the negative-sequence electrical signal.

[0080] Specifically, for case A, the formula

[0081]

[0082] or

[0083]

[0084] or

[0085]

[0086] Get the detection value J K ; Wherein, F(·) represents the negative sequence current threshold which is linearly related to the speed, and V represents the speed of the permanent magnet synchronous motor.

[0087] For case B, the formula

[0088]

[0089] or

[0090]

[0091] or

[0092]

[0093] Get the detection value J K .

[0094] It should be noted that the above method of judging the turn-to-turn short circuit by detecting the negative sequence current / voltage is simple to implement; the above method of using the ratio can more accurately reflect the turn-to-turn short circuit situation; the above method of combining the speed factor can better adapt to different working conditions, but it is necessary to establish an accurate linear relationship model. In practical applications, any of the above methods can be selected to calculate the detection value according to the working condition requirements.

[0095] Step 3: Obtain the original short-circuit fault detection result according to the difference between the initial detection threshold and the detection value.

[0096] The initial detection threshold is determined by the positive sequence electrical signal and negative sequence electrical signal of the permanent magnet traction system under normal operating conditions, and the original short circuit fault detection result is a short circuit fault or no short circuit fault. When the difference is less than zero, the original short circuit fault detection result is no short circuit fault, and when the difference is greater than zero, the original short circuit fault detection result is a short circuit fault.

[0097] In an embodiment of the present invention, the calculation method of the initial detection threshold is the same as the calculation method of the detection value, which uses the positive sequence electrical signal and the negative sequence electrical signal of the permanent magnet traction system in normal operation.

[0098] Step 4: If the original short-circuit fault detection result is a short-circuit fault, the three-stage isolation controller is controlled to close, and the process returns to step 1 to step 3 to obtain a new short-circuit fault detection result. If the new short-circuit fault detection result is the same as the original short-circuit fault detection result, the original short-circuit fault detection result is determined as the final short-circuit fault detection result. Otherwise, the initial detection threshold is updated according to the preset step to obtain an intermediate detection threshold, and the intermediate detection threshold is used as the initial detection threshold in step 3, and the process returns to step 3.

[0099] It should be noted that the purpose of controlling the three-level isolation controller to be closed is to avoid the interference of the inverter on the short-circuit fault detection and to improve the accuracy of the short-circuit fault detection.

[0100] If the new short-circuit fault detection result is different from the original short-circuit fault detection result, it means that the inverter power device may be operating abnormally or the pulse signal link may be abnormal, resulting in unbalanced inverter output and misdiagnosis of the short-circuit fault.

[0101] The following describes the process of updating the initial detection threshold to obtain the intermediate detection threshold.

[0102] Specifically, by calculating the formula

[0103]

[0104] Get the intermediate detection threshold in, Represents the initial detection threshold.

[0105] It is worth mentioning that the present invention is conducive to improving the accuracy of short-circuit fault detection by updating and correcting the threshold in real time.

[0106] It should be noted that when the final short-circuit fault detection result is a short-circuit fault, the corresponding fault information can be sent to the driver terminal or the dispatching command center to maintain and repair the vehicle in a timely manner to avoid safety accidents. Since the permanent magnet synchronous motor uses permanent magnet excitation for the rotor, its no-load back electromotive force increases accordingly with the increase of the motor speed, resulting in that after the motor has a turn-to-turn short-circuit fault, even if the inverter is shut down and the isolation contactor is disconnected, the back electromotive force generated by the continuous operation of the vehicle driving the faulty motor to rotate will form a large short-circuit current at the short-circuit part, generating additional heat that causes the motor temperature to rise sharply and even cause a fire. Therefore, when a turn-to-turn short-circuit occurs in a permanent magnet synchronous traction motor, in addition to blocking the inverter and disconnecting the isolation switch, according to the motor back electromotive force characteristics, the train is required to run at a certain speed limit to the next station to change cars.

[0107] In summary, the short-circuit fault detection method provided by the present invention, when the original short-circuit fault detection result is that a short-circuit fault occurs, controls the three-level isolation controller to close, disconnects the inverter, re-collects the electrical signal and performs detection to obtain a new short-circuit fault detection result. When the original short-circuit fault detection result and the new short-circuit fault detection result are the same, the original short-circuit fault detection result is determined as the final short-circuit fault detection result, which can effectively avoid the interference of the inverter on the short-circuit fault detection and improve the accuracy of the short-circuit fault detection; when the original short-circuit fault detection result and the new short-circuit fault detection result are different, the initial detection threshold can be updated, and the threshold can be updated and corrected in real time, which is beneficial to improving the accuracy of the short-circuit fault detection.

[0108] The short-circuit fault detection device provided by the present invention is described below.

[0109] like Figure 3 As shown, the short circuit fault detection device 300 includes:

[0110] The feature extraction module 301 is used to collect the electrical signal at the output side of the inverter and decompose the electrical signal to obtain a positive sequence electrical signal and a negative sequence electrical signal; the electrical signal is a three-phase current signal or a three-phase voltage signal;

[0111] A detection calculation module 302, used to calculate a detection value for short-circuit fault detection according to the positive-sequence electrical signal and the negative-sequence electrical signal;

[0112] The preliminary detection module 303 is used to obtain an original short-circuit fault detection result according to the difference between the initial detection threshold and the detection value; the initial detection threshold is determined by the positive sequence electrical signal and the negative sequence electrical signal of the permanent magnet traction system under normal operating conditions, and the original short-circuit fault detection result is the occurrence of a short-circuit fault or the absence of a short-circuit fault;

[0113] The re-detection module 304 is used to control the three-level isolation controller to close if the original short-circuit fault detection result is a short-circuit fault, and return to execute the feature extraction module 301 to the preliminary detection module 303 to obtain a new short-circuit fault detection result. If the new short-circuit fault detection result is the same as the original short-circuit fault detection result, the original short-circuit fault detection result is determined as the final short-circuit fault detection result; otherwise, the initial detection threshold is updated according to the preset step to obtain an intermediate detection threshold, and the intermediate detection threshold is used as the initial detection threshold in the preliminary detection module 303, and the preliminary detection module 303 is returned to execute.

[0114] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are not related to the implementation method of the present application.

[0115] The examples are based on the same concept, and their specific functions and technical effects can be specifically referred to in the method embodiment section, which will not be repeated here. Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit, and the above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0116] like Figure 4 As shown, an embodiment of the present invention provides a terminal device, such as Figure 4 As shown, the terminal device D10 of this embodiment includes: at least one processor D100 ( Figure 4 Only one processor is shown in the figure), a memory D101, and a computer program D102 stored in the memory D101 and executable on the at least one processor D100, wherein the processor D100 implements the steps of any of the above-mentioned method embodiments when executing the computer program D102.

[0117] Specifically, when the processor D100 executes the computer program D102, step 1 is executed to collect the electrical signal on the output side of the inverter, and decompose the electrical signal to obtain a positive-sequence electrical signal and a negative-sequence electrical signal; step 2 is to calculate the detection value for short-circuit fault detection based on the positive-sequence electrical signal and the negative-sequence electrical signal; step 3 is to obtain the original short-circuit fault detection result based on the difference between the initial detection threshold and the detection value; step 4 is to control the three-level isolation controller to close if the original short-circuit fault detection result is a short-circuit fault, and return to execute steps 1 to 3 to obtain a new short-circuit fault detection result. If the new short-circuit fault detection result is the same as the original short-circuit fault detection result, the original short-circuit fault detection result is determined as the final short-circuit fault detection result; otherwise, the initial detection threshold is updated according to the preset step to obtain an intermediate detection threshold, and the intermediate detection threshold is used as the initial detection threshold in step 3, and the process returns to execute step 3. Among them, when the original short-circuit fault detection result is a short-circuit fault, the three-level isolation controller is controlled to close, the inverter is disconnected, the electrical signal is re-collected and detected, and a new short-circuit fault detection result is obtained. When the original short-circuit fault detection result and the new short-circuit fault detection result are the same, the original short-circuit fault detection result is determined as the final short-circuit fault detection result, which can effectively avoid the interference of the inverter on the short-circuit fault detection and improve the accuracy of short-circuit fault detection; when the original short-circuit fault detection result and the new short-circuit fault detection result are different, the initial detection threshold can be updated, and the threshold can be updated and corrected in real time, which is conducive to improving the accuracy of short-circuit fault detection.

[0118] The processor D100 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0119] In some embodiments, the memory D101 may be an internal storage unit of the terminal device D10, such as a hard disk or memory of the terminal device D10. In other embodiments, the memory D101 may also be an external storage device of the terminal device D10, such as a plug-in hard disk, a smart memory card (SMC, SmartMedia Card), a secure digital (SD, Secure Digital) card, a flash card (Flash Card), etc. equipped on the terminal device D10. Further, the memory D101 may also include both an internal storage unit of the terminal device D10 and an external storage device. The memory D101 is used to store an operating system, an application program, a boot loader (BootLoader), data and other programs, such as the program code of the computer program, etc. The memory D101 may also be used to temporarily store data that has been output or is to be output.

[0120] An embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented.

[0121] An embodiment of the present application provides a computer program product. When the computer program product runs on a terminal device, the terminal device can implement the steps in the above-mentioned method embodiments when executing the computer program product.

[0122] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0123] One or more embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of the present application should be included in the protection scope of the present application.

Claims

1. A short-circuit fault detection method for a permanent magnet traction system, wherein the permanent magnet traction system comprises a permanent magnet synchronous motor and an inverter connected to the permanent magnet synchronous motor in three phases, and a three-level isolation controller is connected between the permanent magnet synchronous motor and the inverter, characterized in that: The short circuit fault detection method comprises: Step 1, collecting the electrical signal at the output side of the inverter, and decomposing the electrical signal to obtain a positive sequence electrical signal and a negative sequence electrical signal; the electrical signal is a three-phase current signal or a three-phase voltage signal; Step 2, calculating a detection value for short-circuit fault detection according to the positive-sequence electrical signal and the negative-sequence electrical signal; Step 3, obtaining an original short-circuit fault detection result according to the difference between the initial detection threshold and the detection value; the initial detection threshold is determined by the positive-sequence electrical signal and the negative-sequence electrical signal of the permanent magnet traction system under normal operating conditions, and the original short-circuit fault detection result is whether a short-circuit fault occurs or not; Step 4: If the original short-circuit fault detection result is that a short-circuit fault occurs, the three-level isolation controller is controlled to close, and the steps 1 to 3 are returned to be executed to obtain a new short-circuit fault detection result. If the new short-circuit fault detection result is the same as the original short-circuit fault detection result, the original short-circuit fault detection result is determined as the final short-circuit fault detection result; otherwise, the initial detection threshold is updated according to a preset step to obtain an intermediate detection threshold, and the intermediate detection threshold is used as the initial detection threshold in step 3, and the step 3 is returned to be executed.

2. The short circuit fault detection method according to claim 1, characterized in that: Decomposing the electrical signal to obtain a positive-sequence electrical signal and a negative-sequence electrical signal includes: When the electrical signal is a three-phase current signal, the calculation formula is in, Represents the positive sequence current signal, Indicates the inverter output U-phase current, α indicates U-phase, α=e j120 =e -j240 , Indicates the inverter output V phase current, Indicates the inverter output W-phase current, α 2 =e j240 =e -j120 , represents the negative sequence current signal, a, b, c represent the three phases U, V, W on the inverter output side; When the electrical signal is a three-phase voltage signal, the calculation formula is in, Represents the positive sequence voltage signal, Indicates the inverter output UV line voltage, Indicates the inverter output VW line voltage, Indicates the inverter output UW line voltage.

3. The short circuit fault detection method according to claim 2, characterized in that: The calculating, according to the positive-sequence electrical signal and the negative-sequence electrical signal, a detection value for short-circuit fault detection comprises: When the electrical signal is a three-phase current signal, the calculation formula is or or Get the detection value J K ; Wherein, F(·) represents the negative sequence current threshold value which is linearly related to the rotation speed, and V represents the rotation speed of the permanent magnet synchronous motor; When the electrical signal is a three-phase voltage signal, the calculation formula is or or Get the detection value J K .

4. The short circuit fault detection method according to claim 3, characterized in that: The calculation method of the initial detection threshold is the same as the calculation method of the detection value, which uses the positive sequence electrical signal and the negative sequence electrical signal of the permanent magnet traction system in normal operating state.

5. The short circuit fault detection method according to claim 4, characterized in that: The obtaining of an original short-circuit fault detection result according to the difference between the initial detection threshold and the detection value comprises: If the difference is greater than zero, it is determined that the original short-circuit fault detection result is that a short-circuit fault occurs; otherwise, it is determined that the original short-circuit fault detection result is that a short-circuit fault does not occur.

6. The short circuit fault detection method according to claim 5, characterized in that: The updating of the initial detection threshold according to a preset step to obtain an intermediate detection threshold includes: By calculating the formula Get the intermediate detection threshold in, represents the initial detection threshold.

7. The short circuit fault detection method according to claim 1, characterized in that: Before decomposing the electrical signal, the short circuit fault detection method further includes: For any two phase electrical signals in the electrical signals, respectively, based on the two phase electrical signals, calculate a theoretical value of the third phase electrical signal; If the error between the theoretical value of the third phase electrical signal and the actual value of the collected third phase electrical signal is greater than a preset threshold, the third phase electrical signal is recollected until the error is less than or equal to the preset threshold.

8. A short-circuit fault detection device for a permanent magnet traction system, the permanent magnet traction system comprising a permanent magnet synchronous motor and an inverter connected to the permanent magnet synchronous motor in three phases, a three-level isolation controller connected between the permanent magnet synchronous motor and the inverter, characterized in that: include: A feature extraction module, used for collecting the electrical signal at the output side of the inverter, and decomposing the electrical signal to obtain a positive sequence electrical signal and a negative sequence electrical signal; The electrical signal is a three-phase current signal or a three-phase voltage signal; A detection calculation module, used to calculate a detection value for short-circuit fault detection according to the positive-sequence electrical signal and the negative-sequence electrical signal; A preliminary detection module, used for obtaining an original short-circuit fault detection result according to a difference between an initial detection threshold and the detection value; the initial detection threshold is determined by a positive-sequence electrical signal and a negative-sequence electrical signal of the permanent magnet traction system under normal operating conditions, and the original short-circuit fault detection result is whether a short-circuit fault occurs or not; A re-detection module is used to control the three-stage isolation controller to close if the original short-circuit fault detection result is a short-circuit fault, return to execute the feature extraction module to the preliminary detection module, and obtain a new short-circuit fault detection result; if the new short-circuit fault detection result is the same as the original short-circuit fault detection result, the original short-circuit fault detection result is determined as the final short-circuit fault detection result; otherwise, the initial detection threshold is updated according to a preset step to obtain an intermediate detection threshold, and the intermediate detection threshold is used as the initial detection threshold in the preliminary detection module, and the preliminary detection module is returned to execute.

9. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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