Electromagnetic interference prediction modeling, prediction method and system

Abstract

The present invention provides an electromagnetic interference prediction modeling, prediction method and system, including: establishing a key cable harness model; establishing a grounding system model of a traction transformer and a traction motor; establishing an equivalent model of a traction motor based on the fact that when the frequency is high, the internal structure of the traction transformer and the traction motor will form a common mode path due to parasitic capacitance, and the conductor carrying a high-frequency common mode current will generate undesirable electromagnetic radiation; establishing a three-dimensional model of a car body, a rail and an axle counter magnetic head; connecting the above models according to the relationship between the corresponding entities of the model, and establishing an overall radiation model of the interference of the traction converter system to the axle counter. The model can more accurately describe the impact of the EMC interference generated by the traction power supply system of an intercity train on the axle counter.

Description

Technical Field

[0001] The present invention belongs to the technical field of simulation and emulation, and in particular relates to an electromagnetic interference prediction model building, prediction method and system. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Axle counters are widely used track section idle and occupied inspection equipment today. They are the most important aspect of railway transportation safety and play a decisive role in railway operation safety. Therefore, the failure of axle counters seriously affects the normal operation of trains and personnel safety.

[0004] In the past two years, the application of axle counters in urban rail trains with AC power supply in China has caused many electromagnetic compatibility problems. Therefore, it is very necessary to establish an electromagnetic interference prediction model for the traction power supply system of intercity trains to axle counters.

[0005] In the prior art, there is a system for measuring the magnetic field interference of relevant trains on the trackside axle counters. However, the above-mentioned measurement system is a direct measurement through signal collection and processing, which is a lagging measurement and cannot affect the electromagnetic compatibility design of intercity trains and axle counters. In other words, it does not fundamentally solve the electromagnetic compatibility problem between the axle counter and the train vehicle.

[0006] In addition, domestic scholars have done little research on the electromagnetic compatibility between axle counters and train vehicles, and the simulation calculation results are not accurate. For example, there is a semi-physical simulation of the magnetic field EMC of the axle counter of a rail transit vehicle, but the simulation does not really establish a model that matches the actual situation, making it difficult to obtain accurate simulation results. Summary of the invention

[0007] In order to solve the above problems, the present invention proposes a method for building an electromagnetic interference prediction model. The model established by the present invention can more accurately describe the impact of the EMC interference generated by the traction power supply system of the intercity train on the axle counter.

[0008] According to some embodiments, the present invention adopts the following technical solutions:

[0009] In a first aspect, a method for modeling an electromagnetic interference prediction model is disclosed, comprising:

[0010] Establish key cable harness models;

[0011] Establish grounding system model for traction transformer and traction motor;

[0012] Based on the fact that when the frequency is high, the internal structure of the traction transformer and the traction motor will form a common mode path due to parasitic capacitance, and the conductor carrying high-frequency common mode current will generate undesirable electromagnetic radiation, an equivalent model of the traction motor is established;

[0013] Establish three-dimensional models of car body, rails and axle counter magnetic head;

[0014] The above models are connected according to the relationship between the corresponding entities of the models to establish the overall radiation model of the traction inverter system's interference to the axle counter.

[0015] As a further technical solution, the overall radiation model of the interference of the traction converter system to the axle counter is established, including a loop on the input side of the traction converter and a loop on the output side of the traction converter.

[0016] As a further technical solution, the circuit on the input side of the traction converter includes a converter input cable model, a transformer equivalent model, a high-voltage cable model, a grounding system model, a rail model and a vehicle body model.

[0017] As a further technical solution, the circuit on the output side of the traction converter includes an output shielded cable model, a motor equivalent model, a grounding system model, a rail model and a vehicle body model.

[0018] As a further technical solution, in the circuit on the output side of the traction converter, the current excitation port is added between the traction converter and the traction converter housing;

[0019] The motor housing is connected to the grounding system through protective grounding, and the housing grounding of the equipment is connected to the vehicle body through the grounding wire;

[0020] The interference current is transmitted to the traction motor through the traction system cable, then reaches the motor housing through the distributed parameters, is connected to the shaft end through the protective grounding wire, flows in the entire grounding system composed of unshielded wires, and finally returns to the interference source through the vehicle body grounding socket.

[0021] As a further technical solution, the key cable harness model is mainly composed of cables between transformer and converter, cables between converter and motor, and cables in the grounding system;

[0022] Among them, the cables in the grounding system are composed of unshielded wires, and the cables between the traction transformer, traction converter and traction motor are composed of shielded cables. The thickness of the shielding layer is consistent, while the inner conductor radius is different from the outer diameter of the cable.

[0023] As a further technical solution, when establishing the grounding system model of the traction transformer and traction motor:

[0024] The negative pole of the primary side of the traction transformer is connected to the central relay terminal block through a grounding wire, and then divided into two paths to the left and right to reach the corresponding grounding terminal block, and then connected to the shaft end grounding device through a grounding wire to reach the rail;

[0025] This type of high-speed EMU also has a working ground connection between the cars, and the grounding that sends the traction current back to the traction substation is called the working grounding.

[0026] As a further technical solution, the motor housing of the traction motor is connected to the shaft end of the vehicle through a grounding wire, and the shaft end is electrically connected to the rail through a carbon brush and a grounding wire;

[0027] The car body is connected to the central relay terminal block through the car body grounding socket, grounding wire, and grounding resistor. It is also divided into two paths and connected to the corresponding grounding terminal blocks respectively to achieve the connection between the equipment and the rails. It also has the function of ensuring the safety of the car body potential, which is called protective grounding.

[0028] As a further technical solution, the common mode path is a common mode capacitor between the primary winding and the secondary winding;

[0029] The traction motor consists of a stator and a rotor. Its distributed capacitance is calculated using the electrostatic field equation, and its distributed inductance and resistance are calculated using three-dimensional finite element software simulation.

[0030] As a further technical solution, in the process of establishing a three-dimensional model of the car body, rails and axle counter magnetic head, multiple probes are placed in the model to simulate the disturbance patterns of the axle counter at different positions under the car.

[0031] In a second aspect, an electromagnetic interference prediction modeling system is disclosed, comprising:

[0032] The key cable harness model building module is configured to: build a key cable harness model;

[0033] The grounding system establishment module is configured to: model the grounding system model of the traction transformer and the traction motor;

[0034] The traction motor equivalent model establishment module is configured to: establish the traction motor equivalent model based on the fact that when the frequency is high, the internal structures of the traction transformer and the traction motor will form a common mode path due to parasitic capacitance, and the conductor carrying the high-frequency common mode current will generate undesirable electromagnetic radiation;

[0035] The three-dimensional model building module is configured to: build a three-dimensional model of a vehicle body, rails and an axle counter magnetic head;

[0036] The overall radiation model establishment module is configured to: connect the above models according to the relationship between the corresponding entities of the models, and establish an overall radiation model of the interference of the traction inverter system to the axle counter.

[0037] As a further technical solution, the establishment of the overall radiation model of the interference of the traction converter system to the axle counter includes a loop on the input side of the traction converter and a loop on the output side of the traction converter;

[0038] Wherein, in the loop on the output side of the traction converter, the current excitation port is added between the traction converter and the traction converter housing;

[0039] The motor housing is connected to the grounding system through protective grounding, and the housing grounding of the equipment is connected to the vehicle body through the grounding wire;

[0040] The interference current is transmitted to the traction motor through the traction system cable, then reaches the motor housing through the distributed parameters, is connected to the shaft end through the protective grounding wire, flows in the entire grounding system composed of unshielded wires, and finally returns to the interference source through the vehicle body grounding socket.

[0041] In a third aspect, a method for predicting electromagnetic interference radiated by rail is disclosed, comprising:

[0042] Based on the electromagnetic interference prediction model modeling method or system, an interference path model of the train traction power supply system is established;

[0043] Construct the transfer function from the common mode current of the converter input and output cables to the radiated magnetic field of the rail;

[0044] The product of the transfer function curve and the current amplitude spectrum of the cable port is calculated in the frequency domain to obtain the actual external electromagnetic radiation emission intensity of the rail.

[0045] As a further technical solution, when constructing the transfer function of the common-mode current of the converter input and output cables to the rail radiation magnetic field, the wide-band normalized transfer function curve of the system is obtained through three-dimensional simulation.

[0046] In a fourth aspect, a rail radiation electromagnetic interference prediction system is disclosed, comprising:

[0047] The interference path model building module is configured to: establish an interference path model of the train traction power supply system based on the electromagnetic interference prediction model modeling method or system;

[0048] The transfer function building module is configured to: build a transfer function from the common mode current of the converter input and output cables to the magnetic field radiated by the rail;

[0049] The calculation module is configured to calculate the product of the transfer function curve and the current amplitude spectrum of the cable port in the frequency domain to obtain the actual external electromagnetic radiation emission intensity of the rail.

[0050] As a further technical solution, in the calculation module, the radiation field strength F at the axle counter rad It is expressed as the following formula:

[0051]

[0052] Where R(ω,z) is the current element radiation factor, which is related to wiring parameters, frequency and observation point, I c (ω,0) is the port current amplitude, and D(ω,z) is the current distribution function on the cable, which is related to the distance z and the angular frequency ω.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] The electromagnetic interference prediction modeling method of the intercity train traction power supply system on the axle counter of the present invention can more accurately describe the influence of the EMC interference generated by the intercity train traction power supply system on the axle counter, and has a guiding role in the electromagnetic compatibility design of the intercity train and the axle counter.

[0055] The present invention takes into account the electromagnetic compatibility between the axle counter and the train vehicle, and the simulation calculation result of the calculated rail external electromagnetic radiation emission intensity has high accuracy.

[0056] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention.

[0057] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0059] Figure 1 An interference prediction flow chart for an implementation example of the present invention;

[0060] Figure 2(a)-Figure 2(b) This is a schematic diagram of the common mode EMI coupling path of an example implementation example of the present invention;

[0061] Figure 3 This is a schematic cross-sectional view of a sub-cable according to an embodiment of the present invention;

[0062] Figure 4 A schematic diagram of the grounding system of cars 2 and 3 of an embodiment of the present invention;

[0063] Figure 5 This is a schematic diagram of an equivalent model of a traction motor according to an embodiment of the present invention;

[0064] Figure 6 This is a schematic diagram of a three-dimensional model of a vehicle body according to an embodiment of the present invention;

[0065] Figure 7 This is a schematic diagram of the position of the axle counter model and the position of the probe in an embodiment of the present invention;

[0066] Figure 8 A block diagram of modeling the output side of a sub-converter according to an embodiment of the present invention;

[0067] Fig. 9 This is a schematic diagram of node connection of a sub-cable according to an embodiment of the present invention;

[0068] Fig.10 It is a schematic diagram of the connection of the sub-simulation circuit of an embodiment of the present invention;

[0069] Fig.11 This is a schematic diagram of simulation of input cables of a sub-converter according to an embodiment of the present invention;

[0070] Fig.12 This is a schematic diagram of a circuit of a model electric motor according to an embodiment of the present invention;

[0071] Fig.13 This is a schematic diagram of the simulation of the cable on the output side of the sub-traction converter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0072] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0073] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0074] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0075] Embodiment 1:

[0076] In this embodiment, a method and system for predicting electromagnetic interference radiated by rails are disclosed. The method for predicting electromagnetic interference radiated by rails includes:

[0077] Establish the interference path model of the train traction power supply system;

[0078] Construct the transfer function from the common mode current of the converter input and output cables to the rail radiation magnetic field. Based on the idea of ​​transfer function, the electromagnetic radiation emission of the traction converter system of the high-speed EMU is simulated and studied. The principle of transfer function is that when the load characteristics of the traction motor and the cable wiring are fixed, the current of any microelement dz on the cable is related to the current at the starting point. Now define I c (ω,z)=I c (ω,0)D(ω,z), where D(ω,z) is the current distribution function on the cable, which is related to the distance z and the angular frequency ω. The radiated field strength F at the axle counter rad It can be expressed as the following formula:

[0079]

[0080] In the formula, R(ω,z) is the current element radiation factor, which is related to the wiring parameters, frequency and observation point. According to the above formula, the electromagnetic field response amplitude F rad and the port current amplitude I c (ω,0) forms a linear system.

[0081] The specific process is as attached Figure 1 As shown:

[0082] First, the port current Ic is obtained through the vehicle's conducted interference test;

[0083] Secondly, the broadband normalized transfer function curve of the system is obtained through three-dimensional simulation;

[0084] Finally, the product of the transfer function curve and the current amplitude spectrum of the cable port is calculated in the frequency domain to obtain the actual external electromagnetic radiation emission intensity of the rail.

[0085] Rail radiated electromagnetic interference prediction system includes:

[0086] Based on the above rail radiation electromagnetic interference prediction method, an interference path model of the train traction power supply system is established;

[0087] Construct the transfer function from the common mode current of the converter input and output cables to the radiated magnetic field of the rail;

[0088] The product of the transfer function curve and the current amplitude spectrum of the cable port is calculated in the frequency domain to obtain the actual external electromagnetic radiation emission intensity of the rail.

[0089] The transfer function obtained by simulation is added to the current data of the converter output cable obtained by test to obtain the magnetic field radiation intensity generated by the rail. It is compared with the limit value specified by the manufacturer to determine whether it will be disturbed.

[0090] Embodiment 2:

[0091] In this embodiment, a method for building an electromagnetic interference prediction model is disclosed. The method for building an electromagnetic interference prediction model includes:

[0092] Establish key cable harness models;

[0093] Establish grounding system model for traction transformer and traction motor;

[0094] Based on the fact that when the frequency is high, the internal structure of the traction transformer and the traction motor will form a common mode path due to parasitic capacitance, and the conductor carrying high-frequency common mode current will generate undesirable electromagnetic radiation, an equivalent model of the traction motor is established;

[0095] Build car body, rails and 3D models;

[0096] The above models are connected according to the relationship between the corresponding entities of the models to establish the overall radiation model of the traction inverter system's interference to the axle counter.

[0097] Before introducing the construction of the above model in detail, the interference coupling path of the traction system is analyzed first:

[0098] Intercity train vehicles contain two power units, and the power unit structure is consistent, so this example is analyzed based on a certain unit. The parasitic characteristics of the vehicle's traction system are significant, and the parasitic characteristics are mainly manifested as the impedance characteristics of parasitic inductance and parasitic capacitance at high frequencies. Some equipment without physical connection cannot be considered to be electrically insulated at high frequencies. The parasitic parameters mainly depend on the structural layout, such as the parasitic capacitance between the equipment housings and the facing area and distance. It is the common-mode EMI coupling path that can be transmitted to the rails and affect the axle counter magnetic head.

[0099] The traction converter generates transient voltage mutations at the input and output ports, and forms a current loop through the displacement current effect of the parasitic capacitance inside the system. Figure 2(a)-Figure 2(b) The figure shows the connection diagram of the traction converter system located in cars 1 and 2. The main parasitic capacitance includes the common mode capacitance C between the primary and secondary sides of the transformer. transfomer ; Parasitic capacitance C between cable and vehicle body cable ; Parasitic capacitance C between the IGBT bridge arm and the converter housing converter ; Parasitic capacitance C between motor winding and motor housing motor .

[0100] Figure 2(a)-Figure 2(b) The common-mode interference path on the input side of the converter is represented by a colored curve. Since the two phases on the input side are consistent, only the path of interference source A is shown in Figure 2(a)-Figure 2(b).

[0101] The main transmission pathways include:

[0102] ① Bridge arm at point A → Cable at the input side of the converter → C transfomer →Central terminal block→Grounding system→Rail→1 car body ground→C cable → Cable shielding layer on the converter input side → Converter housing → C converter →Bridge arm at point A;

[0103] ② Bridge arm at point A → Cable at the input side of the converter → C transfomer → Central terminal block → Grounding system → Rail → Car 1 body ground → Workshop connection line → Car 2 body ground → Converter grounding line → Converter housing → C converter →Bridge arm at point A;

[0104] ③ Bridge arm at point A → Cable at the input side of the converter → C transfomer → Central terminal block → Grounding system → Rail → Car body ground of car 2 → Converter grounding wire → Converter housing → C converter →Bridge arm at point A.

[0105] The common-mode interference path on the output side of the converter is represented by another color curve. Similarly, only the main propagation path of the U-phase interference source is given:

[0106] ①U-phase bridge arm→Converter output side cable→C motor →Motor housing→Cable shielding layer on converter output side→Converter housing→C converter →U-phase bridge arm.

[0107] ②U-phase bridge arm→converter output side cable→C motor →1 shaft end→grounding system→2 car body ground→C cable → Cable shielding layer on the converter input side → Converter housing → C converter →U phase bridge arm;

[0108] ③U-phase bridge arm→converter output side cable→C motor →1 shaft end→grounding system→2 car body ground→converter ground wire→converter housing→C converter →U-phase bridge arm.

[0109] The following is a detailed introduction to the process of establishing a simulation model for the interference of the traction system on the axle counter:

[0110] According to the analysis of the interference coupling path, the models that need to be established mainly include two aspects. One is the loop on the input side of the traction converter. This interference coupling path includes the converter input cable, transformer equivalent model, grounding system model, rail model and car body model. The connection relationship between the models is shown in Fig. 9 Fig.10; The other part is the output side of the traction converter, which includes the converter output cable, motor equivalent model, grounding system model, rail model and vehicle body model. The main model of interference simulation modeling determined by the interference coupling path has a clear modeling idea and is convenient for partial model replacement according to the cable wiring conditions of different vehicles. It is targeted at fixed vehicles and has a certain degree of universality. The modeling contents of the two parts are the same except for the transformer model and the motor model. The specific modeling methods will be described in sequence below.

[0111] Key cables:

[0112] In order to obtain the electromagnetic radiation emission intensity of the vehicle traction converter system, it is necessary to establish a key cable harness model. The key cables of this type of train are mainly composed of converter input cables, converter output cables and cables in the grounding system. The cables in the grounding system are composed of unshielded wires with a radius of 4mm. The cables between the traction transformer, traction converter and traction motor are composed of shielded cables. The thickness of the shielding layer is consistent, all 0.375mm, while the inner conductor radius is different from the outer diameter of the cable. The inner conductor radius of the input side cable is larger, 7.670mm, and the overall outer diameter of the cable is 29.200mm. The outer diameter of the cable on the output side of the traction converter is slightly thinner than that on the input side. The specific parameters are shown in Table 1. In the electromagnetic simulation software, a three-dimensional model of the corresponding cable is established. The schematic diagram of the cable cross section is shown in the figure. Figure 3 shown.

[0113] Table 1 Cable structure parameters

[0114]

[0115] Grounding system:

[0116] Due to the traction transformer and traction motor in the traction converter system, a complete electrical link needs to be established during modeling, and the grounding of the traction transformer and traction motor needs to be designed. Therefore, a detailed analysis of the grounding system of the EMU is carried out. This type of high-speed EMU adopts a mixed grounding method, that is, the protective grounding and working grounding of the equipment are interconnected.

[0117] This example mainly describes a traction converter system, taking the traction converter system located in cars 1 and 2 as an example, so the grounding system structure of cars 1 and 2 is mainly analyzed. Figure 4As shown, the traction transformer is located in car 1, and the negative pole of the primary side is connected to the central relay terminal block through a grounding wire, which is divided into two paths to the left and right to reach the grounding terminal blocks 2 and 3, and then connected to the shaft end grounding device through a grounding wire to reach the rail. The working grounding of this type of high-speed EMU is also connected between the cars, such as the grounding terminal block 3 of car 2 and the grounding terminal block 2 of car 3 are connected through cables. This grounding that sends the traction current back to the traction substation is called working grounding. The traction motor is located in car 2, and the motor housing is connected to the shaft end of car 1 through a grounding wire. The shaft end is electrically connected to the rail through a carbon brush and a grounding wire. The car body is connected to the central relay terminal block through a car body grounding seat, a grounding wire, and a grounding resistor. It is also divided into two paths and connected to the grounding terminal blocks 1 and 4 respectively, realizing the connection between the equipment and the rail, and has the function of ensuring the safety of the car body potential, which is called protective grounding.

[0118] The key parameters in the grounding system are shown in Table 2:

[0119] Table 2 Grounding system related parameters

[0120]

[0121] Common mode load:

[0122] Through the analysis of the common-mode coupling path, it can be seen that the interference source is generated in the traction converter and reaches the terminal equipment through the cables between the traction transformer and the traction converter and between the traction converter and the traction motor. At low frequencies, the parasitic effects of the equipment cannot be reflected. However, when the frequency is high, the internal structure of the traction transformer and the traction motor will form a common-mode path due to parasitic capacitance, and the conductors carrying high-frequency common-mode current will generate undesirable electromagnetic radiation EMI problems.

[0123] The common mode path of the traction transformer is the common mode capacitance C between the primary winding and the secondary winding. transfomer , which is mainly related to the equivalent distance between the primary and secondary sides of the traction transformer and the relative area between the equivalent layers. Generally, the parasitic capacitance here is in the pF level, and the calculation formula can be written as:

[0124]

[0125] Where ε0 is the dielectric constant of air, ε r is the relative dielectric constant of the insulating material, A is the relative area between layers of the transformer, and d is the equivalent distance between layers. According to the actual situation of the high-speed EMU and the parasitic parameter formula, C transfomer The value is 44.25pF, which serves as the common-mode path of the traction transformer.

[0126] The traction motor consists of a stator and a rotor, and its structure is relatively complex. Its distributed capacitance is obtained through the electrostatic field equation, and the distributed inductance and resistance are obtained through three-dimensional finite element software simulation. The common mode equivalent circuit is as follows: Figure 5 The physical meanings and values ​​of the corresponding parameters are shown in Table 3.

[0127] Table 3 Physical meaning and value of components

[0128]

[0129]

[0130] Overall radiation model of traction inverter system's interference to axle counter:

[0131] The traction converter is the main interference source of the traction converter system. The common-mode current exists in two paths: the converter input side and the converter output side. Since the transfer function method is calculated in the frequency domain, it is impossible to consider the phase relationship between the input side current and the output side current at the same time. Therefore, the vehicle radiation model is divided into two simulations: the converter input side and the output side. Finally, the worst result is considered, that is, the radiation field is in phase, and the simulation result with the maximum radiation intensity is obtained.

[0132] The sub-technical scheme of the embodiment of the present invention is aimed at this simulation modeling demand. The active part obtains interference through testing, and the data is relatively accurate; the passive part obtains the transfer function through simulation; then the result is obtained by multiplying the data of the two parts, and the result is relatively accurate; the model structure parameters are easy to adjust according to the actual situation, and after the transfer function of the model is simulated using the transfer function method, it is only necessary to test the current data of the existing vehicle and combine it with the transfer function to obtain the prediction result.

[0133] The 3D model of the vehicle body is established in the 3D view, and the models of vehicles 1 to 4 are established. Since the small structures on the vehicle body have little effect on the radiation emission of the whole vehicle, the bolts, nuts and other parts on the vehicle body, as well as some small hole structures are ignored, and only the body structure and skirt are considered. Figure 6 The rail model and the axle counter magnetic head model also use three-dimensional models, and the probe positions are placed according to international standards, such as Figure 7 In order to study the disturbance law of the axle counter at different positions under the vehicle, a total of 6 probes are placed in the model, as shown in Figure 7 Indicated by the arrow.

[0134] The modeling block diagram of the traction converter output side is as follows: Figure 8 As shown in the figure, the frame is the current excitation port, which is added between the traction converter and the traction converter housing. The motor housing is connected to the grounding system through protective grounding, and the housing grounding of the equipment is connected to the vehicle body through the grounding wire. The cable model after considering the grounding system is shown in the attached figure. Fig. 9As shown: the numbers are the cable node numbers, the curves are the unshielded grounded cables, and also include the shielded cables of the traction converter system. The interference current is transmitted to the traction motor through the traction system cables, and then reaches the motor housing through the distributed parameters, connected to the shaft end through the protective grounding wire, flows in the entire grounding system composed of unshielded wires, and finally returns to the interference source through the vehicle body grounding socket.

[0135] In the circuit design, a model is established according to the actual structure, and each module is connected. The excitation source is added between the input cable of the traction inverter and its casing ground. The input cable shielding layer is connected to the inverter casing, so the input cable shielding layer in the circuit is equivalent to the inverter casing, which is grounded through the equivalent impedance of the grounding cable. The front end of the transformer is connected to the central terminal block, and the rear end is connected to the inverter input cable. The shielding layer of the inverter input cable is also connected to the transformer casing, so the inverter input cable connected to the inverter node can be regarded as the transformer casing, which is grounded through the grounding cable, and the inverter output cable is connected to the motor model. The grounding resistance of the two cars is grounded through the grounding socket. The transformer of car 1 is grounded, and the car body is grounded through the equivalent impedance of the workshop connecting line to the common grounding point of car 2.

[0136] Embodiment three:

[0137] Based on the method of the second embodiment, a modeling system for predicting the interference of the common mode current input to the axle counter of the converter is disclosed, including:

[0138] The key cable harness model building module is configured to: build a key cable harness model;

[0139] The grounding system establishment module is configured to: model the traction transformer and grounding system models;

[0140] The module for establishing the equivalent model of the traction transformer is configured as follows: based on the fact that when the frequency is high, the internal structure of the traction transformer will form a common mode path due to parasitic capacitance, and the conductor carrying the high-frequency common mode current will generate undesirable electromagnetic radiation;

[0141] The three-dimensional model building module is configured to: build a three-dimensional model of a vehicle body and rails;

[0142] The overall radiation model establishment module is configured to: connect the above models according to the relationship between the corresponding entities of the models, and establish the overall radiation model of the interference of the common mode current input of the traction converter on the axle counter, such as Figure 10-11 .

[0143] In this implementation example, the specific implementation process of the system can refer to the implementation process of the relevant method in the second implementation example, which will not be repeated here.

[0144] Embodiment 4:

[0145] Based on the method of the first embodiment, a rail radiation electromagnetic interference prediction system is disclosed, comprising:

[0146] The interference path model building module is configured to: establish an interference path model of the train traction power supply system based on the electromagnetic interference prediction model modeling method;

[0147] The transfer function building module is configured to: build a transfer function from the common mode current of the converter input and output cables to the magnetic field radiated by the rail;

[0148] The calculation module is configured to calculate the product of the transfer function curve and the current amplitude spectrum of the cable port in the frequency domain to obtain the actual external electromagnetic radiation emission intensity of the rail.

[0149] In this implementation example, the specific implementation process of the system can refer to the implementation process of the relevant method in the first implementation example, which will not be repeated here.

[0150] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0151] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0152] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0153] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0154] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0155] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A method for modeling an electromagnetic interference prediction model, characterized in that: include: Establish key cable harness models; Establish grounding system model for traction transformer and traction motor; Based on the fact that when the frequency is high, the internal structure of the traction transformer and the traction motor will form a common mode path due to parasitic capacitance, and the conductor carrying high-frequency common mode current will generate undesirable electromagnetic radiation, an equivalent model of the traction motor is established; Establish three-dimensional models of car body, rails and axle counter magnetic head; The above models are connected according to the relationship between the corresponding entities of the models to establish the overall radiation model of the traction inverter system's interference to the axle counter; The establishment of the overall radiation model of the interference of the traction converter system to the axle counter includes a loop on the input side of the traction converter and a loop on the output side of the traction converter; In the circuit on the output side of the traction converter, the current excitation port is added between the traction converter and the traction converter housing; The motor housing is connected to the grounding system through protective grounding, and the housing grounding of the equipment is connected to the vehicle body through the grounding wire; The interference current is transmitted to the traction motor through the traction system cable, then reaches the motor housing through the distributed parameters, is connected to the shaft end through the protective grounding wire, flows in the entire grounding system composed of unshielded wires, and finally returns to the interference source through the vehicle body grounding socket.

2. The electromagnetic interference prediction modeling method according to claim 1, characterized in that: The key cable harness model is composed of cables between transformer and converter, cables between converter and motor, and cables in the grounding system; Among them, the cables in the grounding system are composed of unshielded wires, and the cables between the traction transformer, traction converter and traction motor are composed of shielded cables. The thickness of the shielding layer is consistent, while the inner conductor radius is different from the outer diameter of the cable.

3. The electromagnetic interference prediction modeling method according to claim 1, characterized in that: When modeling the grounding system of the traction transformer and traction motor: The negative pole of the primary side of the traction transformer is connected to the central relay terminal block through a grounding wire, and then divided into two paths to the left and right to reach the corresponding grounding terminal block, and then connected to the shaft end grounding device through a grounding wire to reach the rail; The working grounding of high-speed EMUs is also connected between the cars, and the grounding that sends the traction current back to the traction substation is called working grounding.

4. The electromagnetic interference prediction modeling method according to claim 3, characterized in that: Also includes: The motor housing of the traction motor is connected to the shaft end of the vehicle through a grounding wire, and the shaft end is electrically connected to the rail through a carbon brush and a grounding wire; The car body is connected to the central relay terminal block through the car body grounding socket, grounding wire, and grounding resistor. It is also divided into two paths and connected to the corresponding grounding terminal blocks respectively to achieve the connection between the equipment and the rails. It also has the function of ensuring the safety of the car body potential, which is called protective grounding.

5. An electromagnetic interference prediction modeling system, characterized in that: include: The key cable harness model building module is configured to: build a key cable harness model; The grounding system establishment module is configured to: model the grounding system model of the traction transformer and the traction motor; The traction motor equivalent model establishment module is configured to: establish the traction motor equivalent model based on the fact that when the frequency is high, the internal structures of the traction transformer and the traction motor will form a common mode path due to parasitic capacitance, and the conductor carrying the high-frequency common mode current will generate undesirable electromagnetic radiation; The three-dimensional model building module is configured to: build a three-dimensional model of a vehicle body, rails and an axle counter magnetic head; The overall radiation model establishment module is configured to: connect the above-mentioned models according to the relationship between the entities corresponding to the models, and establish an overall radiation model of the interference of the traction inverter system to the axle counter; The establishment of the overall radiation model of the interference of the traction converter system to the axle counter includes a loop on the input side of the traction converter and a loop on the output side of the traction converter; Wherein, in the loop on the output side of the traction converter, the current excitation port is added between the traction converter and the traction converter housing; The motor housing is connected to the grounding system through protective grounding, and the housing grounding of the equipment is connected to the vehicle body through the grounding wire; The interference current is transmitted to the traction motor through the traction system cable, then reaches the motor housing through the distributed parameters, is connected to the shaft end through the protective grounding wire, flows in the entire grounding system composed of unshielded wires, and finally returns to the interference source through the vehicle body grounding socket.

6. A method for predicting electromagnetic interference radiated by rails, characterized in that: include: Establishing an interference path model of the train traction power supply system based on any electromagnetic interference prediction model modeling method of claims 1-4 or the system described in claim 5; Construct the transfer function from the common mode current of the converter input and output cables to the radiated magnetic field of the rail; The product of the transfer function curve and the current amplitude spectrum of the cable port is calculated in the frequency domain to obtain the actual external electromagnetic radiation emission intensity of the rail.

7. The method for predicting rail radiated electromagnetic interference according to claim 6, characterized in that: When constructing the transfer function from the common-mode current of the converter input and output cables to the rail radiation magnetic field, the wide-band normalized transfer function curve of the system is obtained through three-dimensional simulation.

8. Rail radiated electromagnetic interference prediction system, characterized by: include: An interference path model building module is configured to: establish an interference path model of a train traction power supply system based on any electromagnetic interference prediction model building method of claims 1 to 4 or the interference path model building method of claim 5; The transfer function building module is configured to: build a transfer function from the common mode current of the converter input and output cables to the magnetic field radiated by the rail; The calculation module is configured to calculate the product of the transfer function curve and the current amplitude spectrum of the cable port in the frequency domain to obtain the actual external electromagnetic radiation emission intensity of the rail.

9. The rail radiation electromagnetic interference prediction system according to claim 8, characterized in that: In the calculation module, the radiation field strength at the axle counter F rad It is expressed as the following formula: In the formula, R ( ω , z ) is the current element radiation factor, which is related to wiring parameters, frequency and observation point. is the port current amplitude, D ( ω , z ) is the current distribution function on the cable, and is related to the distance z With angular frequency ω Related.

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