A method and system for input over-current suppression of a four-quadrant rectifier of a motor train unit

Abstract

This invention discloses a method and system for suppressing input overcurrent in a four-quadrant rectifier of a high-speed train, comprising the following steps: acquiring the transformer secondary voltage, four-quadrant output voltage value, and four-quadrant input current value; acquiring the voltage difference between the four-quadrant output voltage setpoint and the four-quadrant output voltage value to obtain a target current value; acquiring a four-quadrant voltage adjustment signal; acquiring the output voltage value and acquiring a PWM pulse signal; and controlling the power switching device according to the PWM pulse signal. This invention uses the four-quadrant voltage adjustment signal to acquire a PWM pulse signal to control the power switching device, thereby maintaining the stability of the four-quadrant output voltage while ensuring that the four-quadrant input current does not exceed the protection value. It does not affect the normal control performance of the four-quadrant rectifier, does not require adjustment of control parameters, and ensures the response speed of the intermediate voltage, thus maintaining the stability of the intermediate voltage.

Description

Technical Field

[0001] This invention relates to the field of high-speed train circuit protection technology, and in particular to a method and system for suppressing input overcurrent of a four-quadrant rectifier in a high-speed train. Background Technology

[0002] The traction power of railway EMUs comes from a single-phase 25kV, 50Hz AC power supply to the overhead contact line. The four-quadrant rectifier of the EMU is a pulse width modulation converter, powered by a constant 50Hz, 25kV AC power supply, with a DC output. Its load is an AC motor controlled by an inverter. Its working principle involves adjusting the amplitude of the output DC voltage and the phase of the four-quadrant input current through pulse width control, ensuring the waveform of the input current is as consistent as possible with the power supply voltage, while maintaining a stable output DC voltage at the target value. During normal operation, the single-phase four-quadrant rectifier needs to adjust the pulses according to the locked grid frequency and phase to maintain normal operation. However, in actual use, the four-quadrant power supply relies on friction between the pantograph and the overhead contact line. Affected by line conditions and locomotive speed, the pantograph may temporarily disconnect from the contact line, or changes in wheel-rail adhesion conditions may cause fluctuations in the AC motor torque, leading to the four-quadrant input current exceeding the protection value. This could damage or restart the EMU's electrical equipment, affecting normal operation and causing economic losses.

[0003] In existing methods for suppressing overcurrent at the input of four-quadrant rectifiers, the four-quadrant current regulation loop performs proportional-integral calculations on the difference between the setpoint and actual value of the four-quadrant input current. This results in current overshoot during actual output, causing the current to exceed the protection value, leading to incomplete suppression of four-quadrant input current overcurrent. While reducing the regulation parameters of the four-quadrant rectifier current loop can be effective, the speed at which the input current tracks the rectifier directly affects the speed of intermediate voltage deviation adjustment. Therefore, fluctuations in the load or input power supply can cause significant fluctuations in the intermediate voltage, potentially leading to undervoltage or overvoltage faults. Summary of the Invention

[0004] This invention provides a method and system for suppressing input overcurrent in a four-quadrant rectifier of a high-speed train to overcome the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for suppressing input overcurrent in a four-quadrant rectifier of a high-speed train includes the following steps:

[0007] S1: Obtain the secondary voltage u of the transformer N Four-quadrant output voltage value u d Four-quadrant input current value i;

[0008] S2: Based on the four-quadrant output voltage value u d Obtain the four-quadrant output voltage setpoint u d * With the four-quadrant output voltage value u d The voltage difference between them is used to obtain the target current value i. cmd ;

[0009] S3 calculates the four-quadrant input current value i and the target current value i cmd Acquire four-quadrant voltage regulation signal C out ;

[0010] S4: According to the four-quadrant voltage adjustment signal C out Obtain the output voltage value U out ;

[0011] S5: Based on the output voltage value U out and the secondary voltage u of the transformer N The PWM pulse signal is acquired to control the power switching device according to the PWM pulse signal.

[0012] Furthermore, in step S4, the output voltage value U is obtained. out The method is as follows:

[0013]

[0014] In the formula, i max The input current protection value for the four-quadrant rectifier control; i is the four-quadrant input current value; f is the four-quadrant rectifier control frequency; L is the transformer secondary inductance value; C out It is a four-quadrant adjustment signal.

[0015] An overcurrent suppression system based on a method for suppressing overcurrent input of a four-quadrant rectifier in a high-speed train includes a pulse generation module, an intermediate voltage control loop, a four-quadrant current regulation loop, and a four-quadrant current limiting loop.

[0016] The intermediate voltage control loop is used to adjust the transformer secondary voltage u. N Four-quadrant output voltage value u d Four-quadrant input current value i, obtain target current value i cmd ;

[0017] The four-quadrant current regulating loop is used to adjust the four-quadrant input current value i and the target current value i. cmd Acquire four-quadrant voltage regulation signal C out ;

[0018] The four-quadrant current limiting ring is used to limit the output voltage value u in the four quadrants. d and four-quadrant voltage regulation signal Cout Obtain the output voltage value U out ;

[0019] The pulse generation module is used to generate the pulse based on the output voltage value U. out and the secondary voltage u of the transformer N It acquires PWM pulse signals to control power switching devices.

[0020] Furthermore, the power switching device is a semiconductor power device.

[0021] Furthermore, the intermediate voltage control loop uses a DSP chip circuit.

[0022] Beneficial Effects: The present invention provides a method and system for suppressing overcurrent input in a four-quadrant rectifier for high-speed trains. It obtains the output voltage value through a four-quadrant voltage regulation signal, and then acquires a PWM pulse signal. The power switching devices are controlled according to the PWM pulse signal, thereby maintaining a stable four-quadrant output voltage while ensuring that the four-quadrant input current does not exceed the protection value. This solves the problem that existing four-quadrant rectifier control methods cause four-quadrant input current fluctuations exceeding the protection value when the input power supply voltage or output load fluctuates. It does not affect the normal control performance of the four-quadrant rectifier, does not require adjustment of control parameters, ensures the response speed of the intermediate voltage, and thus maintains the stability of the intermediate voltage. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a flowchart of the input overcurrent suppression method for the four-quadrant rectifier of a high-speed train according to the present invention;

[0025] Figure 2 This is a structural diagram of the input overcurrent suppression system of the four-quadrant rectifier of the EMU in an embodiment of the present invention;

[0026] Figure 3 This is a signal flow diagram of the input overcurrent suppression system of the four-quadrant rectifier of the EMU in an embodiment of the present invention;

[0027] Figure 4 This is an equivalent schematic diagram of the four-quadrant rectifier of the EMU in an embodiment of the present invention;

[0028] Figure 5This is a waveform diagram of the moment when the power grid voltage of the EMU changes abruptly in an embodiment of the present invention;

[0029] Figure 6 This is a four-quadrant input current waveform diagram in an embodiment of the present invention where the method of the present invention is not implemented;

[0030] Figure 7 This is a four-quadrant input current waveform diagram of the real-time method of the present invention in an embodiment of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This embodiment provides a method for suppressing input overcurrent in a four-quadrant rectifier of a high-speed train, such as... Figure 1 As shown, it includes the following steps:

[0033] S1: Obtain the secondary voltage u of the transformer through the signal acquisition circuit. N Four-quadrant output voltage value u d The four-quadrant input current value i, and the transformer side voltage u N Four-quadrant output voltage value u d The four-quadrant input current value i is transmitted to the DSP chip circuit; such as Figure 4 The diagram shown illustrates the equivalent principle of a four-quadrant rectifier for a high-speed train.

[0034] S2: The intermediate voltage control loop in the DSP chip circuit outputs the voltage value u according to the four quadrants. d Obtain the four-quadrant output voltage setpoint u d * With the four-quadrant output voltage value u d The voltage difference between them is used to obtain the target current value i. cmd ;

[0035] Specifically, in this embodiment, the four-quadrant output voltage setpoint u is obtained through the intermediate voltage control loop in the DSP chip circuit. d * With the four-quadrant output voltage value u d The deviation between them, i.e., the voltage difference, is fed into the proportional-integral (PI) stage in the intermediate voltage control loop to output the target current value i. cmd The methods used are conventional techniques in the field and will not be described in detail here.

[0036] S3: The four-quadrant current regulating loop adjusts the current based on the four-quadrant input current value i and the target current value i. cmd Acquire four-quadrant voltage regulation signal C out ;

[0037] Specifically, in this embodiment, the four-quadrant input current value i and the target current value i are compared. cmd After subtraction, proportional and integral operations are performed to obtain the four-quadrant voltage regulation signal C. out This is a standard technique and will not be described in detail here.

[0038] S4: According to the four-quadrant voltage adjustment signal C out The voltage is fed into a four-quadrant current limiting loop for limiting calculation to obtain the output voltage value U. out ;

[0039] Preferably, the output voltage value U is obtained. out The method is as follows:

[0040]

[0041] In the formula, i max The input current protection value for the four-quadrant rectifier control; i is the four-quadrant input current value; f is the four-quadrant rectifier control frequency; L is the transformer secondary inductance value; C out It is a four-quadrant adjustment signal;

[0042] S5: Based on the output voltage value U out and the secondary voltage u of the transformer N Obtain the PWM pulse signal;

[0043] Specifically, the output voltage value U out Then, after passing through the transformer secondary voltage u N The calculation involves determining the PWM pulse signal, which is then amplified by the drive circuit and transmitted to the power module circuit to drive the power switching devices for on / off switching. This ensures that the four-quadrant output voltage remains stable while the four-quadrant input current does not exceed the protection value. The method for calculating the PWM pulse signal is existing technology in the field and will not be described in detail here.

[0044] S6: Control the power switching device according to the PWM pulse signal.

[0045] This invention also discloses an input overcurrent suppression system for a four-quadrant rectifier of a high-speed train, such as... Figure 2 As shown, it includes a pulse generation module, an intermediate voltage control loop, a four-quadrant current regulation loop, and a four-quadrant current limiting loop;

[0046] The intermediate voltage control loop is used to control the transformer secondary voltage u acquired by the signal acquisition circuit. N Four-quadrant output voltage value u d Four-quadrant input current value i, obtain target current value i cmd ;

[0047] The four-quadrant current regulating loop is used to adjust the four-quadrant input current value i and the target current value i. cmd Acquire four-quadrant voltage regulation signal C out ;

[0048] The four-quadrant current limiting ring is used to adjust the signal C according to the four-quadrant voltage. out Obtain the output voltage value U out ;

[0049] The pulse generation module is used to generate the pulse based on the output voltage value U. out and the secondary voltage u of the transformer N It acquires PWM pulse signals to control power switching devices.

[0050] Specifically, such as Figure 3 As shown, in this embodiment, the secondary voltage of the transformer is obtained through a voltage transformer. The four-quadrant input current value and the four-quadrant output voltage value are obtained through a current sensor and a voltage sensor, respectively. The signal acquisition circuit sends the secondary voltage signal, four-quadrant input current signal, and four-quadrant output voltage signal acquired by the voltage transformer, current sensor, and voltage sensor to the DSP chip circuit to generate a switching signal. This signal is then sent to the drive circuit to generate a drive signal, which in turn drives the power switching device to turn on / off. The power switching device can be a semiconductor power device such as an IGBT or GTO. The signal acquisition circuit and the DSP chip circuit are PCB circuit boards, and the drive circuit is a dedicated drive circuit for semiconductor power devices such as IGBTs and GTOs.

[0051] This invention regulates the voltage signal C output by the four-quadrant rectifier by adding a four-quadrant current limiting loop. out This limitation ensures that the pulse switching signal generated by the four-quadrant rectifier control will not cause a four-quadrant input overcurrent fault.

[0052] Figure 5 , 6 7 are comparisons of the effects after implementing the technical solution of the present invention, wherein... Figure 5 It is the waveform at the moment of sudden voltage change in the power grid; Figure 6 The four-quadrant input current waveform does not implement the method of this invention; Figure 7 This is the four-quadrant input current waveform when implementing the method of this invention. As can be seen from the figure, the peak value of the four-quadrant input current without implementing the method of this invention exceeds 1500A during a sudden change in grid voltage. Figure 7 The method of this invention sets the four-quadrant current protection limit value to 1000A. After the implementation of this invention, when a sudden change in grid voltage occurs, the four-quadrant input current can be limited to within 1000A.

[0053] The beneficial effects of this invention are as follows:

[0054] 1. The overcurrent suppression method for the input of the four-quadrant rectifier of the EMU in this invention does not affect the normal control performance of the four-quadrant rectifier, does not require adjustment of control parameters, ensures the response speed of the intermediate voltage, and thus maintains the stability of the intermediate voltage.

[0055] 2. The overcurrent suppression method for the input of the four-quadrant rectifier of the EMU in this invention does not affect the normal operation of the four-quadrant rectifier, can limit the four-quadrant input current, avoid the occurrence of four-quadrant input overcurrent faults, ensure the normal operation of the EMU, and improve the reliability of the traction four-quadrant rectifier of the EMU.

[0056] 3. The overcurrent suppression method for the input of the four-quadrant rectifier of the EMU of the present invention does not require additional hardware costs, is easy to implement, and is easy to promote.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing input overcurrent in a four-quadrant rectifier of a high-speed train, characterized in that, Includes the following steps: S1: Obtain the secondary voltage of the transformer u N Four-quadrant output voltage values u d Four-quadrant input current values i ; S2: Based on the four-quadrant output voltage values u d Obtain the four-quadrant output voltage setpoint. u d * With the four-quadrant output voltage value u d The voltage difference between them is used to obtain the target current value. i cmd ; S3: Based on the four-quadrant input current values i With the target current value i cmd Obtain four-quadrant voltage regulation signals ; S4: Adjust the voltage signal according to the four quadrant voltage. Obtain the output voltage value ; Among them, the output voltage value is obtained. The method is as follows: In the formula, This is the protection value for the control input current of the four-quadrant rectifier. These are the four-quadrant input current values. f It is a four-quadrant rectifier controlling the frequency; L This is the value of the secondary inductance of the transformer; It is a four-quadrant adjustment signal; S5: Based on the output voltage value and the secondary voltage of the transformer u N The PWM pulse signal is acquired to control the power switching device according to the PWM pulse signal.

2. The overcurrent suppression system of the four-quadrant rectifier input overcurrent suppression method for high-speed trains according to claim 1, comprising a pulse generation module, characterized in that, Includes intermediate voltage control loop, four-quadrant current regulation loop, and four-quadrant current limiting loop; The intermediate voltage control loop is used to output voltage values ​​based on the four quadrants. u d Obtain the four-quadrant output voltage setpoint. u d * With the four-quadrant output voltage value u d The voltage difference between them is used to obtain the target current value. i cmd ; The four-quadrant current regulating loop is used to adjust the input current value in the four quadrants. i With the target current value i cmd Acquire four-quadrant voltage regulation signal ; The four-quadrant current limiting ring is used to adjust the signal according to the four-quadrant voltage. Obtain the output voltage value ; The pulse generation module is used to generate the pulse based on the output voltage value. and the secondary voltage of the transformer u N It acquires PWM pulse signals to control power switching devices.

3. The overcurrent suppression system of the four-quadrant rectifier input overcurrent suppression method for EMU trains according to claim 2, characterized in that, The power switching device is a semiconductor power device.

4. The overcurrent suppression system of the four-quadrant rectifier input overcurrent suppression method for high-speed trains according to claim 2, characterized in that, The intermediate voltage control loop uses a DSP chip circuit.

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