Method for improving track signal compatibility of alternating-current drive locomotive

Abstract

A method for improving track signal compatibility of an alternating-current drive locomotive. Throughout the entire speed range of locomotive operation, control of an inverter of a traction converter is implemented using a combination of random switching frequency control and fixed switching frequency control, effectively avoiding a track harmonic current generated by IGBT chopper control, and thus suppressing the amplitude of the track harmonic current. The method solves the problem in the prior art that it is difficult to improve the track signal compatibility of the alternating-current drive locomotive.

Description

A method for improving the compatibility of track signals for AC transmission locomotives Technical Field

[0001] The present invention relates to the technical field of locomotives, and in particular to a method for improving the compatibility of track signals of an AC transmission locomotive. Background Art

[0002] Many developed countries (such as Australia) have long-standing lines, and some track circuit equipment is outdated and easily triggered by interference. Therefore, they have extremely high requirements for track signal compatibility. The maximum allowable track current is only 1 / 3 of the domestic and European standards, which are 300mA.

[0003] AC transmission locomotives are complex system equipment that integrates mechanical, power electronic and electrical equipment. Solving their track signal compatibility is a relatively complex technical issue. The measures currently commonly used to control the track signal compatibility of the entire vehicle mainly include: improving the emission and anti-interference capabilities of key electrical components (such as traction converter cabinets, auxiliary converter cabinets, resistance brake cabinets, and microcomputer network control systems); and optimizing the control methods such as vehicle equipment layout, wiring, and grounding.

[0004] However, given that the above measures are all technical measures related to physical structure, when the track signal compatibility of the entire vehicle does not meet the requirements of relevant standards, it is difficult to change the equipment layout of the entire vehicle. This leads to the difficult situation where it may be necessary to incur high costs to optimize the physical structure and electromagnetic performance of the core product, but the effect of the improvement cannot be determined.

[0005] Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a method for improving the compatibility of track signals of AC transmission locomotives, which solves the problems existing in the prior art such as the difficulty in improving the compatibility of track signals of AC transmission locomotives.

[0007] The technical solution adopted by the present invention to solve the above problems is:

[0008] A method for improving the compatibility of track signals of an AC transmission locomotive adopts a combination of random switching frequency control and fixed switching frequency control to control the inverter of a traction converter in the full speed range of the locomotive.

[0009] As an optimal technical solution, for the speed range 0~V1, random switching frequency PWM is used to control the inverter; for the speed range V1~V2, fixed switching frequency PWM is used to control the inverter; where V1 represents one of the locomotive speeds and V2 represents the second locomotive speed.

[0010] As an optimal technical solution, the dynamic braking control strategy of AC transmission locomotives adopts a direct resistance braking method: the IGBT chip is fully turned on, the energy generated by the traction motor is directly transmitted to the resistance braking device, and the intermediate DC link voltage value is determined by the dynamic braking power.

[0011] As a preferred technical solution, the circuit adopted in the resistance braking direct investment method includes: an IGBT chip, a diode D1, and a braking resistor R. One end of the IGBT chip is electrically connected to the positive pole DC+ of the intermediate DC circuit, the other end of the IGBT chip is electrically connected to the cathode of D1, the anode of D1 is electrically connected to the negative pole DC- of the intermediate DC circuit, and the two ends of the braking resistor R are electrically connected to the cathode and anode of D1.

[0012] As a preferred technical solution, the IGBT chip model is IBBM120S5.

[0013] As a preferred technical solution, an electromagnetic shielding structure is provided on the traction motor close to the axle side and / or the rail surface side.

[0014] As a preferred technical solution, the electromagnetic shielding structure is fixed on the motor base.

[0015] As a preferred technical solution, the electromagnetic shielding structure is fixed on the motor cylinder.

[0016] As a preferred technical solution, the electromagnetic shielding structure is a magnetic isolation plate.

[0017] As a preferred technical solution, the AC traction motor is a fully laminated motor.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) By adopting the method of the present invention, the amplitude of the track interference current generated during the operation of the locomotive can be reduced by 50%-70%;

[0020] (2) The method of the present invention is a method for improving the signal compatibility of locomotives based on vehicle-level software control, which is easy to implement and has low implementation cost;

[0021] (3) In order to reduce harmonics and amplitude, the present invention changes the resistance braking operating mode from IGBT chopping control to direct switching. The IGBT elements are fully turned on and there is no IGBT chopping. The direct switching of resistance braking means that the energy generated by the traction motor is directly transmitted to the resistance braking. The intermediate DC link voltage value is completely determined by the dynamic braking power. It effectively avoids the track harmonic current generated by IGBT chopping control, thereby suppressing the amplitude of the track harmonic current.

[0022] (4) The present invention adopts physical electromagnetic shielding measures, that is, a magnetic isolation plate is set on the axle side and rail surface side of the traction motor, and the magnetic isolation plate is fixed on the motor base or cylinder to eliminate or reduce the electromagnetic leakage of the traction motor, thereby reducing the induced current generated in the closed loop of the wheelset and rail due to electromagnetic leakage, thereby achieving the purpose of reducing the amplitude of the track interference current. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram showing the principle of track interference current formation;

[0024] Figure 2 is a schematic diagram of the switching frequency control strategy of the traction converter;

[0025] Figure 3 is a schematic diagram of the resistance braking control strategy;

[0026] Figure 4 is a schematic diagram of the position of the exposed core laminations of the motor (viewing angle 1);

[0027] Figure 5 is a schematic diagram of the position of the exposed core laminations of the motor (viewing angle 2);

[0028] Figure 6 is a schematic diagram of the installation of the magnetic isolation plate.

[0029] Markings and their corresponding names in the accompanying drawings: 1. axle side motor core laminations, 2. motor bottom motor core laminations, 3. motor top motor core laminations, 4. non-axle side motor core laminations. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0031] Example 1

[0032] As shown in Figures 1 to 6, the present invention is a method for improving the compatibility of track signals in AC transmission locomotives. It is a method for controlling signal compatibility based on vehicle-level software control. It can effectively solve the problems described in the background technology and can effectively control the track current amplitude generated by the closed-loop effect during locomotive operation to below 100mA, avoiding interference with the audio track circuit and the DPU (Data Pickup Unit) track circuit, so that the vehicle track signal compatibility meets the requirements of high international standards.

[0033] The amplitude of track interference current is an important indicator of the compatibility of track signals on AC locomotives. The amplitude of track interference current is mainly affected by common mode voltage, axle induced voltage, and electromagnetic field coupling induced voltage, as shown in Figure 1. The extent to which these three voltages affect track current is still unknown. Analysis shows that the main sources of track current are as follows:

[0034] (1) The common-mode voltage generated by the traction converter flows through the traction motor housing and bogie frame to the wheelset and finally to the track;

[0035] (2) The electromagnetic radiation of the traction motor is cut through the axle, generating an induced voltage on the axle, which flows directly to the track through the wheelset;

[0036] (3) A large AC current flows through the traction motor, motor cable and axle. This current generates electromagnetic radiation, which forms a voltage on the rail through near-field coupling, thereby generating a coupling current.

[0037] In general, track current is affected by both conduction and radiation.

[0038] The method for improving the compatibility of AC transmission locomotive track signals described in the present invention is a method for improving locomotive signal compatibility based on vehicle-level software control, which aims to reduce the amplitude of track interference current. The specific scheme is as follows:

[0039] 1. Traction converter inverter control strategy - random switching frequency PWM control + fixed switching frequency PWM control:

[0040] In the full speed range of the locomotive, the traction converter inversion adopts a control method that combines random switching frequency and fixed switching frequency.

[0041] The random switching frequency modulation strategy is to randomly change the switching frequency within a range, so that the harmonic components with larger amplitudes in the harmonic spectrum can be dispersed and the spectrum becomes sparse, thereby making the harmonic distribution along the frequency axis of the spectrum more continuous.

[0042] For speeds with large harmonic amplitudes (0-V1), random switching frequency PWM control is used to evenly distribute the harmonic components of the inverter's output voltage and current across a wide frequency band, suppressing large current spikes at the frequency multiplication. For speeds with harmonic amplitudes that meet requirements (V1-V2), fixed switching frequency PWM control is used. As shown in Figure 2, the random switching frequency f1>f3>f2, where f1 must be less than the maximum switching frequency the IGBT can withstand.

[0043] 2. Dynamic braking control strategy - direct injection:

[0044] For AC locomotives, the conventional control mode for resistance braking is to convert the locomotive's kinetic energy into electrical energy through the traction motor. This is achieved through IGBT chopper control in the traction converter. The IGBTs act as switching elements, and the duty cycle is adjusted to maintain a constant DC link voltage under varying braking power. This traditional resistance braking control mode results in high track harmonic current amplitudes.

[0045] In order to reduce harmonics and amplitude, the present invention changes the resistance braking operating condition from IGBT chopping control to direct control. The IGBT elements are fully turned on and there is no IGBT chopping. The direct control of resistance braking means that the energy generated by the traction motor is directly transmitted to the resistance braking device. The intermediate DC link voltage value is completely determined by the dynamic braking power. It effectively avoids the track harmonic current generated by IGBT chopping control, thereby suppressing the amplitude of the track harmonic current.

[0046] 3. Traction motor electromagnetic shielding:

[0047] Currently, AC traction motors are generally fully laminated. The motor housing does not fully enclose the core laminations, leaving some laminations exposed. See Figures 4 and 5 for specific locations. During operation, electromagnetic leakage occurs through the four locations shown in Figures 4 and 5 (axle-side motor core lamination 1, motor core lamination 2 at the bottom of the motor, motor core lamination 3 at the top of the motor, and motor core lamination 4 at the non-axle side), generating induced currents in the closed loop between the wheelset and rails.

[0048] Considering that electromagnetic leakage on the axle side and the bottom of the motor has the greatest impact on the track current, the present invention adopts physical electromagnetic shielding measures, that is, a magnetic isolation plate is set on the axle side and the rail surface side of the traction motor, and the magnetic isolation plate is fixed on the motor base or cylinder (installation diagram is shown in Figure 6), thereby eliminating or reducing the electromagnetic leakage of the traction motor, thereby reducing the induced current generated in the closed loop of the wheelset and rail due to electromagnetic leakage, and achieving the purpose of reducing the amplitude of the track interference current.

[0049] By adopting the method of the present invention, the amplitude of the track interference current generated during the operation of the locomotive can be reduced by 50%-70%.

[0050] The method of the present invention is a method for improving the signal compatibility performance of a locomotive mainly based on vehicle-level software control, which is easy to implement and has low implementation cost.

[0051] As described above, the present invention can be preferably implemented.

[0052] All features disclosed in all embodiments in this specification, or steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0053] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Based on the technical essence of the present invention and within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement of the above embodiment shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for improving the compatibility of track signals of AC transmission locomotives, characterized in that: In the full speed range of the locomotive, the control of the inverter of the traction converter adopts a combination of random switching frequency control and fixed switching frequency control.

2. A method for improving the compatibility of AC transmission locomotive track signals according to claim 1, characterized in that: For the speed range 0 to V1, the inverter is controlled by random switching frequency PWM; for the speed range V1 to V2, the inverter is controlled by fixed switching frequency PWM; Among them, V1 represents the first locomotive speed, and V2 represents the second locomotive speed.

3. A method for improving the compatibility of AC transmission locomotive track signals according to claim 1, characterized in that: The dynamic braking control strategy of AC transmission locomotives adopts a direct resistance braking method: the IGBT chip is fully turned on, the energy generated by the traction motor is directly transmitted to the resistance braking device, and the intermediate DC link voltage value is determined by the dynamic braking power.

4. A method for improving the compatibility of AC transmission locomotive track signals according to claim 3, characterized in that: The circuit used in the resistance braking direct investment method includes: IGBT chip, diode D1, and braking resistor R. One end of the IGBT chip is electrically connected to the positive pole DC+ of the intermediate DC circuit, and the other end of the IGBT chip is electrically connected to the cathode of D1. The anode of D1 is used to be electrically connected to the negative pole DC- of the intermediate DC circuit. The two ends of the braking resistor R are electrically connected to the cathode of D1 and the anode of D1.

5. A method for improving the compatibility of track signals of AC transmission locomotives according to claim 4, characterized in that: The IGBT chip model is IBBM120S5.

6. A method for improving the compatibility of track signals of an AC transmission locomotive according to any one of claims 1 to 5, characterized in that: An electromagnetic shielding structure is provided on the traction motor close to the axle side and / or the rail surface side.

7. A method for improving the compatibility of AC transmission locomotive track signals according to claim 6, characterized in that: The electromagnetic shielding structure is fixed on the motor base.

8. A method for improving the compatibility of track signals of AC transmission locomotives according to claim 6, characterized in that: The electromagnetic shielding structure is fixed on the motor cylinder.

9. A method for improving the compatibility of AC transmission locomotive track signals according to claim 6, characterized in that: The electromagnetic shielding structure is a magnetic isolation plate.

10. The method for improving the compatibility of AC transmission locomotive track signals according to claim 1, characterized in that: The AC traction motor is a fully laminated motor.

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