Device for simulating active EMI filtering of motor train unit traction system

Abstract

The utility model discloses a device for simulating active EMI filtering of a traction system of a motor train unit, which comprises a traction transformer, a traction converter, a traction motor and an active filter, and is characterized in that the traction transformer is linked with a pantograph, acquires 25KV / 50HZ alternating current from an alternating current contact network and transmits the alternating current to the primary side of the traction transformer; the secondary side of the traction transformer is connected with a traction converter, and the output end of the traction converter is connected with a traction motor; the active filter comprises a sampling circuit which is used for collecting a current signal of a main circuit between the traction transformer and the traction converter, and the current signal is amplified and then compensated to the main circuit. The electric signals adjusted by the active filter are adjusted into three-phase alternating current with low frequency and voltage amplitude in the main circuit through the traction converter, and then the three-phase alternating current is transmitted to a three-phase asynchronous motor side for motor driving. According to the utility model, the electromagnetic environment of the motor train unit traction system can be accurately simulated, and the electromagnetic interference in the operation process can be reduced.

Description

Technical Field

[0001] This utility model belongs to the field of electromagnetic compatibility testing for high-speed trains, and in particular relates to a device for simulating active EMI filtering in the traction system of a high-speed train. Background Technology

[0002] In recent years, the equipment contained in high-speed trains has become increasingly diversified, with continuous increases in traction current and power. High-power and electronic equipment are becoming more digitalized, intelligent, and integrated, leading to a more complex electromagnetic environment inside the train and intensified electromagnetic interference generated and received by the equipment. Electromagnetic interference refers to destructive electromagnetic effects generated by a system, which can cause permanent malfunctions and damage in severe cases. Therefore, electromagnetic interference problems increase the probability of safety accidents in high-speed trains. Researching and solving electromagnetic interference problems in high-speed trains has significant theoretical and practical implications.

[0003] Common EMI suppression measures for traction systems address the issue from three angles: cutting off the interference source, blocking the coupling path, and protecting sensitive equipment. Among these, cutting off the interference source is the most efficient and thorough solution, fundamentally resolving the electromagnetic interference problem.

[0004] Active EMI filters are widely used in the field of electromagnetic compatibility (EMI) of high-speed trains due to their small size and high efficiency. However, the structure and environment of the high-speed train traction system are relatively complex, and the experimental testing cost is high. Therefore, this paper designs an active EMI filter device for the high-speed train traction system to simulate the working environment of the traction system and the active EMI filter, and eliminates noise signals. This can provide effective data support for the research on electromagnetic interference problems of high-speed trains. Utility Model Content

[0005] The purpose of this invention is to provide a device for simulating the active EMI filtering of a high-speed train traction system, used to simulate the electromagnetic environment of the BTM equipment. It simulates the working environment of the high-speed train traction system and the electromagnetic interference elimination process.

[0006] This utility model is implemented as follows:

[0007] An active EMI filter for a simulated high-speed train traction system includes: a traction transformer, a traction converter, a traction motor, and an active filter. The traction transformer is connected to a pantograph, receiving 25kV / 50Hz AC power from an AC contact network and supplying it to the primary side. The secondary side of the traction transformer is connected to the traction converter, and the output of the traction converter is connected to the traction motor. The active filter includes a sampling circuit for acquiring the current signal of the main circuit between the traction transformer and the traction converter; the current signal is amplified and then compensated for in the main circuit.

[0008] Furthermore, the sampling circuit is a current transformer, with the primary side of the current transformer connected in series in the main circuit, and the secondary side of the current transformer connected in parallel with a resistor R1 for sampling.

[0009] Furthermore, the active filter also includes an amplifier circuit, which includes resistors R2 and R3. One end of resistor R2 is connected to one end of resistor R1, and the other end of resistor R2 is connected to the inverting input terminal of the amplifier. One end of resistor R3 is connected to the other end of resistor R1, and the other end of resistor R3 is connected to the non-inverting input terminal of the amplifier. The output terminal of the amplifier is connected to the base of two transistors, the emitters of the two transistors are connected together, and the collectors of the two transistors are grounded.

[0010] Furthermore, the two transistors include transistor Q1 and transistor Q2, wherein transistor Q1 is NPN type and transistor Q2 is PNP type.

[0011] Furthermore, the collector of transistor Q1 is connected to the positive power supply terminal of the amplifier, and the collector of transistor Q2 is connected to the negative power supply terminal of the amplifier.

[0012] Furthermore, the emitters of the two transistors are connected to one end of resistor R5 and then to the inverting input of the amplifier via resistor R4. The other end of resistor R5 is connected to the non-inverting input of the amplifier via resistor R6.

[0013] Furthermore, the other end of resistor R4 is connected to capacitor C, the other end of capacitor C is grounded, and connected to the traction converter.

[0014] Compared with the prior art, the advantages of this utility model are:

[0015] This novel structure utilizes a model of the EMU traction system to simulate the electromagnetic environment during actual operation. It combines this model with a feedback-type current sampling and current compensation (FB-CSCC) active filter to simulate the process of injecting noise signals obtained by reverse amplification and sampling back into the main circuit for noise cancellation. This simulates the electromagnetic interference suppression process of the EMU as realistically as possible. The structure is simple and easy to implement. Attached Figure Description

[0016] Figure 1 This is a general structural diagram of an active EMI filter device for a high-speed train traction system according to this utility model;

[0017] Figure 2 This is a circuit diagram illustrating the circuit principle of an active EMI filter device for a high-speed train traction system according to this utility model. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.

[0019] See Figure 1 As shown, this utility model provides a device for active EMI filtering of a simulated EMU traction system; it includes: a traction transformer, a traction converter, a traction motor, and a sampling current compensation device that is an active filter feedback type current sampling current compensation device.

[0020] The traction transformer is connected to the pantograph, receiving 25kV / 50Hz AC power from the AC contact network and supplying it to the primary side. The secondary side of the traction transformer is connected to a traction converter, the output of which is connected to the traction motor. The active filter includes a sampling circuit for collecting the current signal of the main circuit between the traction transformer and the traction converter. The current signal is amplified and then compensated for in the main circuit. Based on the operating conditions of Chinese standardized EMUs, the 25kV / 50Hz AC power from the AC contact network is reduced to 1850V / 50Hz AC power.

[0021] Specifically, the traction transformer is connected to the pantograph, and obtains 25KV / 50HZ AC power from the AC contact network to the primary side of the traction transformer; the secondary side of the traction transformer is connected to the traction converter, and the output end of the traction converter is connected to the traction motor; the active filter includes a sampling circuit for collecting the current signal of the main circuit between the traction transformer and the traction converter, and the current signal is amplified and compensated to the main circuit.

[0022] The traction transformer in this application reduces the high voltage to an input voltage suitable for different EMU train sets. The traction transformer samples the voltage through an active filter, performs noise cancellation, and finally sends the voltage back to the traction converter, adjusting it to three-phase AC for motor drive.

[0023] In one embodiment, the active filter includes a sampling circuit for acquiring the current signal of the main circuit between the traction transformer and the traction converter. The current signal is amplified and compensated to the main circuit. The sampling circuit is a current transformer, with its primary side connected in series in the main circuit and a resistor R1 connected in parallel to the secondary side for sampling. Applying the principle of electromagnetic induction, the noise signal of the main circuit is sampled and transmitted to the secondary coil, forming a sampling stage with the resistor R1.

[0024] The design of the current transformer needs to ensure that the detection signal is not distorted. Taking into account the size constraints, the magnetic ring should be selected with high permeability as much as possible. Therefore, the relevant parameters for current activation are: turns ratio 50, load resistance 10Ω, magnetic core relative permeability 7912μ, and excitation inductance 9.2μH.

[0025] In one embodiment, the active filter further includes an amplifier circuit, which includes resistors R2 and R3. One end of resistor R2 is connected to one end of resistor R1, and the other end of resistor R2 is connected to the inverting input terminal of the amplifier. One end of resistor R3 is connected to the other end of resistor R1, and the other end of resistor R3 is connected to the non-inverting input terminal of the amplifier. The output terminal of the amplifier is connected to the base of two transistors, the emitters of the two transistors are connected together, and the collectors of the two transistors are grounded.

[0026] The secondary side of the current transformer is connected to the amplifier input through resistors R3 and R2. The amplification circuit must ensure that the main parameters of the selected amplifier do not interfere with the amplification effect. Therefore, the voltage feedback operational amplifier AD847 should be selected, with a gain-bandwidth product of 50MHz, a slew rate of 50, and a supply voltage of ±15V.

[0027] The amplifier comprises two transistors, Q1 and Q2, wherein Q1 is an NPN type and Q2 is a PNP type. The collector of transistor Q1 is connected to the positive power supply terminal of the amplifier, and the collector of transistor Q2 is connected to the negative power supply terminal of the amplifier. The emitters of both transistors are connected to one end of resistor R5, and then connected to the inverting input terminal of the amplifier through resistor R4. The other end of resistor R5 is connected to the non-inverting input terminal of the amplifier through resistor R6.

[0028] The main components of the compensation circuit are resistor R5 and capacitor C. Considering that the maximum value of the injected current should be consistent with the maximum value of the original noise current, the value of resistor R4 is calculated to be 2.5Ω. The capacitor C should be selected according to the actual situation, taking the maximum capacitance value that is suitable for the size of the equipment space.

[0029] The processed noise signal is transmitted back to the main circuit through capacitor C for noise cancellation, thereby reducing the noise current, and then enters the traction converter stage for adjustment.

[0030] The noise signal sampled by the current transformer is transmitted to the amplification circuit. After processing by the amplification circuit, a compensation current with increased amplitude but opposite direction to the original noise is obtained. This compensation current passes through the capacitor C of the compensation circuit and is grounded together with the main circuit, thus transmitting the compensation current back to the traction circuit in the main circuit.

[0031] In the converter stage, the original noise signal is canceled out. The function of capacitor C here is to further filter out the DC signal in the compensation current.

[0032] The function of the traction converter is to realize the conversion and feedback of electrical energy, including PWM rectifier, Buck-Boost chopper circuit and PWM inverter.

[0033] See Figure 2 As shown, the traction converter is an existing component. Employing a two-level, four-quadrant PWM rectifier improves the overall system power factor and reduces current harmonic components. The two-level, four-quadrant PWM rectifier converts the AC output from the traction transformer into a 3600V intermediate DC bus voltage, with a switching frequency of 250Hz.

[0034] The Buck-Boost chopper circuit inside the traction converter adjusts the intermediate DC bus voltage to a DC voltage with an amplitude below 2800V. The LC filter in the intermediate DC circuit can eliminate the second harmonic to a certain extent.

[0035] The internal inverter stage of the traction converter adopts a three-phase two-level PWM inverter to adjust the DC voltage to a three-phase AC voltage with variable frequency for driving the traction motor. The traction motor is usually a three-phase asynchronous motor, and the working conditions are that the driving voltage must meet the requirements of variable frequency and voltage within 0 to 2800V.

[0036] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for simulating active EMI filtering in a high-speed train traction system, characterized in that, include: The system includes a traction transformer, a traction converter, a traction motor, and an active filter. The traction transformer is connected to a pantograph and receives 25kV / 50Hz AC power from the AC contact network, which is then supplied to the primary side of the traction transformer. The secondary side of the traction transformer is connected to the traction converter, and the output of the traction converter is connected to the traction motor. The active filter includes a sampling circuit for collecting the current signal of the main circuit between the traction transformer and the traction converter. The current signal is amplified and then compensated for in the main circuit.

2. The active EMI filter device for simulating a high-speed train traction system according to claim 1, characterized in that, The sampling circuit is a current transformer. The primary side of the current transformer is connected in series with the main circuit, and the secondary side of the current transformer is connected in parallel with a resistor R1 for sampling.

3. The active EMI filter device for a simulated EMU traction system according to claim 2, characterized in that, The active filter also includes an amplifier circuit, which includes resistors R2 and R3. One end of resistor R2 is connected to one end of resistor R1, and the other end of resistor R2 is connected to the inverting input terminal of the amplifier. One end of resistor R3 is connected to the other end of resistor R1, and the other end of resistor R3 is connected to the non-inverting input terminal of the amplifier. The output terminal of the amplifier is connected to the base of two transistors, the emitters of the two transistors are connected together, and the collectors of the two transistors are grounded.

4. The active EMI filter device for a simulated EMU traction system according to claim 3, characterized in that, The two transistors include transistor Q1 and transistor Q2, wherein transistor Q1 is NPN type and transistor Q2 is PNP type.

5. The active EMI filter device for a simulated EMU traction system according to claim 4, characterized in that, The collector of transistor Q1 is connected to the positive power supply terminal of the amplifier, and the collector of transistor Q2 is connected to the negative power supply terminal of the amplifier.

6. The active EMI filter device for a simulated EMU traction system according to claim 4, characterized in that, The emitters of the two transistors are connected to one end of resistor R5, and then connected to the inverting input of the amplifier through resistor R4. The other end of resistor R5 is connected to the non-inverting input of the amplifier through resistor R6.

7. The active EMI filter for a simulated high-speed train traction system according to claim 6, characterized in that, The other end of resistor R4 is connected to capacitor C, and the other end of capacitor C is grounded and connected to the traction converter.

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