CN105890744A - Method for determining snakelike instability of rail vehicle - Google Patents

Abstract

A determination method for rail vehicle serpentine instability, including noise-assisted empirical mode (EEMD) decomposition, instantaneous frequency (and amplitude), generalized zero-crossing (GZC) frequency (and amplitude), and nonlinear index calculation method. If the train has a serpentine instability, the nonlinear index of the train will be enhanced, and the possible instability will be warned accordingly. The invention provides a new judging method for serpentine instability, which calculates the instantaneous frequency, instantaneous amplitude, zero-crossing average frequency (and amplitude) and nonlinear index, and judges whether the serpentine instability is based on the nonlinear index. The shortcoming of the unreliable determination method in the prior art is solved.

Description

A Judgment Method for Serpentine Instability of Rail Vehicles

technical field

The invention relates to a judging method, in particular to a judging method for a rail vehicle serpentine instability.

Background technique

Train safety is the primary consideration for train operation, so domestic and foreign manufacturers have designed different monitoring systems and equipment to monitor the train operating status. These detection systems and equipment widely use accelerometers and strain gauges to monitor key parts, including the monitoring of train safety indicators and stability indicators. However, at present, there is no national standard for judging train serpentine instability in China. Usually, such a processing method is adopted: carry out 0.5-10 Hz band-pass filtering on the lateral vibration acceleration of the train bogie. -10m/s^2, it is considered that the train is laterally unstable (serpentine instability). However, this method has a large filtering range, and the filtered signal may have signals other than the serpentine wave. The peak definition of the six continuous waves has no theoretical basis, and there may be misjudgment of the serpentine instability.

With the increase of train speed, the requirements for transportation safety are getting higher and higher, so it is particularly important to carry out early warning and control of train serpentine instability. Therefore, it is of great significance to use detection technology to monitor the running state of EMUs in real time, and to propose a new method for accurate early warning of possible serpentine instability.

Contents of the invention

The main purpose of the present invention is to solve the technical problem of how to judge the serpentine instability, and provide a method for judging the serpentine instability of a rail vehicle.

For realizing the above object, technical scheme of the present invention is:

A method for judging the serpentine instability of a rail vehicle. Two acceleration sensors arranged diagonally are arranged on the bogie, and the instantaneous frequency IF(t) and the average frequency of zero crossing IF _zc are respectively calculated for the lateral acceleration signals of the sensors at both ends of the bogie (t) and amplitude A _zc (t), through the instantaneous frequency IF (t), zero-crossing average frequency IF _zc (t) and amplitude A _zc (t) to calculate the nonlinear index INL, through the nonlinear The indicator INL judges whether the serpentine is unstable or not.

Further, according to the lateral acceleration signals of the sensors at both ends of the bogie, the serpentine characteristic wave c _j is extracted respectively, and the instantaneous frequency IF( _t ), the average frequency of zero-crossing point IF _zc (t) and the amplitude A _zc ( t).

Further, the noise-assisted EEMD empirical mode decomposition is performed on the lateral acceleration signal of the sensor at one end of the bogie to obtain multiple modal components c _i ;

Calculate the average frequency for each IMF And compare them with the theoretical serpentine frequency f _ci one by one, calculate

ε is the error tolerance;

If Δf _ci >ε, it is considered that there is no serpentine frequency component, and the EMU has no serpentine instability;

On the contrary, select the modal component c _j with the smallest Δf _ci as the serpentine characteristic wave.

Further, calculate instantaneous frequency IF (t), zero-crossing point average frequency IF _zc (t) and amplitude A _zc (t) to serpentine characteristic wave c _j ;

Calculate the nonlinearity index INL of the serpentine eigenwave c _j :

$\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; IF</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; IF</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \%</span>}$

Furthermore, the nonlinear index INL is calculated separately for the lateral acceleration signals of the sensors at both ends of the bogie. If the frequency of the serpentine characteristic wave of the lateral acceleration at both ends of the bogie is consistent and the nonlinear indexes of both are greater than the threshold, it is considered that the EMU has a serpentine failure. stable.

Further, the snake-like instability determination method is applied to the snake-like instability suppression system, and the snake-like instability suppression system includes a snake-like early warning and control module, which is used to judge whether the bogie is In a state of serpentine instability;

Traction motor speed control system, used to control the speed of the traction motor according to the judgment of the serpentine early warning and control module;

The signal output end of the serpentine early warning and control module is connected to the traction motor speed control system.

Further, the serpentine instability suppression system also includes a lateral acceleration measurement module for measuring the lateral vibration acceleration of the bogie;

The signal output end of the lateral acceleration measurement module is connected with the signal input end of the serpentine early warning and control module;

The serpentine early warning and control module judges whether the bogie is in a serpentine instability state according to the data transmitted by the lateral acceleration measurement module.

Further, the traction motor speed control system includes a given speed control module, which is used to select the original given speed sp1 or the adjusted given speed sp2 according to the control signal k transmitted by the serpentine warning and control module and the adjusted given speed sp2. The final given speed sp2 is transmitted to the speed controller module;

The speed controller module is used to receive the given speed and actual speed, and transmit the given flux flux ^* and given torque Torque ^* to the DTC control module;

The DTC control module is used to receive the current I_ab and voltage V_abc transmitted by the traction motor measurement module, the given flux flux ^* and the given torque Torque ^* transmitted by the speed controller module, and send driving to the switching device of the traction motor inverter signal g;

The control signal output end and the given speed output end of the serpentine early warning and control module are respectively connected with the control signal input end and the given speed input end of the given speed control module, and the given speed control module's given speed The output end is connected with the given speed input end of the speed controller module, the actual speed input end of the speed controller module is connected with the traction motor speed output end, the given flux linkage output end of the speed controller module, given The torque output terminals are respectively connected with the given flux linkage input terminal and the given torque input terminal of the DTC control module, and the voltage and current input terminals of the DTC control module are respectively connected with the voltage and current output terminals of the traction motor measurement module, The drive signal output terminal of the DTC control module is connected with the traction motor inverter.

Further, the serpentine instability suppression system also includes a display module for displaying parameter changes of the rail vehicle serpentine instability suppression system;

The signal input end of the display module is respectively connected with the speed controller module, the output end of the traction motor speed, and the serpentine early warning and control module.

Further, the lateral acceleration measurement module includes a sensor module, a GPS module, a data acquisition module, a main control unit MCU module, and a data processing and analysis module;

The data acquisition module is respectively connected with the sensor module and the GPS module, and the main control unit MCU module is respectively connected with the data acquisition module, data processing and analysis module.

In summary, a method for judging the serpentine instability of a rail vehicle according to the present invention provides a new method for judging the serpentine instability, which calculates the instantaneous frequency, the instantaneous amplitude and the nonlinear index, and according to the nonlinear index Judging whether the serpentine is unstable or not solves the unreliable shortcoming of the judging method in the prior art.

Description of drawings

Fig. 1 is a serpentine instability direct torque control diagram of the present invention;

Fig. 2 is a schematic diagram of the results of the lateral acceleration measurement module of the present invention.

detailed description

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

The method for judging the serpentine instability of a rail vehicle according to the present invention is mainly used in a rail vehicle serpentine instability suppression system, and is used as a method for judging whether the rail vehicle is in a serpentine instability.

The rail vehicle serpentine instability suppression system includes a serpentine early warning and control module and a traction motor speed control system, and the signal output end of the serpentine early warning and control module is connected to the traction motor speed control system. The serpentine early warning and control module is used to judge whether the bogie is in a serpentine instability state, and the traction motor speed control system is used to control the speed of the traction motor according to the judgment of the serpentine early warning and control module. Whether the bogie is in a serpentine instability state is judged by the serpentine warning and control module. If it is in a serpentine instability state, the speed of the traction motor is controlled to decrease, which can effectively eliminate the serpentine instability of the rail vehicle.

In this embodiment, the serpentine early warning and control module uses the method of calculating the vibration nonlinear index to judge whether the bogie is in a serpentine instability, and realizes the direct control of the traction motor speed through the direct torque control (DTC) theory.

Specifically, as shown in Figure 1, the rail vehicle serpentine instability suppression system includes a serpentine early warning and control module, a lateral acceleration measurement module, a given speed control module, a speed controller module, and a DTC control module. The control signal output end and the given speed output end of the serpentine early warning and control module are respectively connected to the control signal input end and the given speed input end of the given speed control module, and the given speed output end of the given speed control module is connected to the speed The given speed input terminal of the controller module is connected, the actual speed input terminal of the speed controller module is connected with the speed output terminal of the traction motor, the given flux linkage output terminal and the given torque output terminal of the speed controller module are respectively connected with the DTC control The given flux linkage input terminal and given torque input terminal of the module are connected, the voltage and current input terminals of the DTC control module are respectively connected with the voltage and current output terminals of the traction motor measurement module, and the driving signal output terminal of the DTC control module is connected with the traction motor measurement module. Motor inverter connection.

As shown in Figure 2, the lateral acceleration measurement module is used to measure the lateral vibration acceleration of the bogie, and the signal output end of the lateral acceleration measurement module is connected to the signal input end of the snake warning and control module. The lateral acceleration measurement module includes a sensor module, a GPS module, a data acquisition module, a main control unit MCU module, a data processing and analysis module, and a data storage unit. The data acquisition module is connected with the sensor module and the GPS module respectively, and the main control unit MCU module is connected with the The data collection module, the data processing and analysis module, and the data storage unit are connected.

Two acceleration sensors are installed diagonally above the spring tube of the bogie frame to measure the lateral acceleration of the bogie. Data communication is carried out between the GPS module and the MCU module of the main control unit through the RS-232 serial port. Through the GPS module, it can be determined at what speed and where the nonlinear index of the train is obtained. The data acquisition module uses the A/D conversion chip to realize the acquisition of the analog signal of the bogie acceleration. The data processing and analysis module is used to analyze and process the characteristics of serpentine instability.

The data acquisition module and GPS module are packaged in an iron box and fixed in the equipment compartment under the EMU. The acceleration sensor adopts a strain acceleration sensor, and its sampling frequency is set to 1000Hz by default. The GPS test parameters are the speed and position of the train, and its sampling frequency is set to 10Hz by default.

The output ends of the two measuring points (ydd1, ydd2) of the lateral acceleration measurement module are respectively connected to the two input ends of the snake warning and control module, and the lateral vibration accelerations ydd1 and ydd2 of the two measuring points are transmitted to the snake warning and control module. The control module performs the next calculation.

The serpentine early warning and control module uses the method of calculating the vibration nonlinear index to judge whether the bogie is in a serpentine instability. The calculation of the vibration nonlinear index includes the following steps:

(1) Perform noise-assisted EEMD empirical mode decomposition on the lateral acceleration signal of the sensor at one end of the bogie to obtain multiple modal components c _i ;

(2) Calculate the average frequency for each IMF And compare them with the theoretical serpentine frequency f _ci one by one, calculate

ε is the error tolerance;

If Δf _ci >ε, it is considered that there is no serpentine frequency component, and the EMU has no serpentine instability;

Conversely, choose the modal component c _j with the smallest Δf _ci as the serpentine characteristic wave;

(3) Calculate the instantaneous frequency IF(t), the generalized zero-crossing (GZC) frequency IF _zc (t) and the amplitude A _zc (t) of the serpentine characteristic wave c _j ;

(4) Calculate the nonlinear index INL of the serpentine characteristic wave c _j :

$\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; IF</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; IF</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \%</span>}$

(5) Repeat (1) to (4) for the lateral vibration acceleration of the other sensor at the opposite end of the bogie;

(6) If the frequency of the serpentine characteristic wave of the lateral acceleration at two opposite corners of the bogie is consistent and the nonlinear indexes of both are greater than the threshold, it is considered that the EMU has a serpentine instability.

The above-mentioned new snake-like instability determination method calculates the instantaneous frequency, instantaneous amplitude and nonlinear index, and judges whether the snake-like instability is unstable or not according to the nonlinear index, which solves the unreliable shortcoming of the prior art judgment method.

The control signal output end and the given speed output end of the serpentine early warning and control module are respectively connected with the control signal input end and the given speed input end of the given speed control module. After the calculation and judgment of the serpentine warning and control module through the above steps, if the bogie is in a serpentine instability state, it sends the control signal k and the adjusted given speed sp2 to the given speed control module.

The given speed control module is used for switching between the original given speed sp1 and the adjusted given speed sp2. If the train is running stably, the original given speed sp1 will be transmitted to the speed controller module; if the train is in a serpentine instability state, after receiving the control signal k, the given speed control module will adjust the given speed sp2 is transmitted to the speed controller module as a given speed N ^* .

The speed controller module is used to receive the given speed and actual speed, and transmit the given flux flux ^* and given torque Torque ^* to the DTC control module. According to the adjusted given rotational speed sp2 (given rotational speed N ^* ), the speed controller module outputs the given flux linkage Flux ^* to the DTC control module through the flux linkage look-up table, and the speed controller module compares the given rotational speed sp2 with the actual value of the traction motor After the speed (N) is compared (N ^* -N), the given torque Torque ^* is output to the DTC control module through the PI regulator.

The DTC control module is used to receive the current I_ab and voltage V_abc transmitted by the traction motor measurement module, the given flux flux ^* and given torque Torque ^* transmitted by the speed controller module, and send drive signals to the switching devices of the traction motor inverter g.

The DTC control module calculates the actual flux linkage and actual torque according to the current I_ab and voltage V_abc transmitted by the received traction motor measurement module, and takes the difference between the given flux linkage Flux ^* and given torque Torque ^* and the actual flux linkage and actual torque Values, through the torque and flux linkage hysteresis comparators respectively, are input into the voltage switch vector table together with the flux linkage sector, and the appropriate voltage vector is selected to control the switching device of the traction motor inverter by sending the driving signal g.

The present invention realizes the direct control of the traction motor speed through the direct torque control (DTC) theory. Compared with the prior art which can only reduce the lateral vibration of the train, the present invention reduces the running speed of the train and can eliminate the serpentine instability .

The rail vehicle serpentine instability suppression system also includes a display module. The display system is used to display the parameter changes of the rail vehicle serpentine instability suppression system, including current, speed, flux linkage, electromagnetic torque, reference torque, measured acceleration, linear indicators, etc. The signal input end of the display module is respectively connected with the speed controller module, the output end of the traction motor speed, and the serpentine early warning and control module.

A method for suppressing serpentine instability of a rail vehicle utilizing the above-mentioned device, comprising the steps of:

Step 1. The serpentine early warning and control module calculates the vibration nonlinear index according to the measured lateral vibration acceleration of the bogie to determine whether the bogie is in a serpentine instability state.

Step 2. If the bogie is in the state of serpentine instability, a reference speed lower than the current speed of the traction motor is given, and the traction motor is controlled to reduce the speed to reduce the running speed of the rail vehicle.

Specifically, if the bogie is in a serpentine instability state, the serpentine early warning and control module transmits the control signal k and the adjusted given speed sp2 to the given speed control module, and the given speed control module transmits the adjusted given speed The rotational speed sp2 is transmitted to the speed controller module.

According to the given rotational speed sp2, the speed controller module outputs the given flux flux ^* to the DTC control module through the flux linkage look-up table, and the speed controller module compares the given rotational speed sp2 with the actual rotational speed of the traction motor and outputs the given through the PI regulator Torque Torque ^* to DTC control module.

The DTC control module calculates the actual flux linkage and actual torque according to the current I_ab and voltage V_abc transmitted by the received traction motor measurement module, and takes the difference between the given flux linkage Flux ^* and given torque Torque ^* and the actual flux linkage and actual torque Values, through the torque and flux linkage hysteresis comparators respectively, are input into the voltage switch vector table together with the flux linkage sector, and the appropriate voltage vector is selected to control the switching device of the traction motor inverter by sending the driving signal g.

As mentioned above, a similar technical solution can be derived in combination with the content of the solution given in the accompanying drawings. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention are still within the scope of the technical solutions of the present invention.

Claims (10)

1. a rail vehicle serpentine instability judging method is characterized in that: bogie is provided with two acceleration sensors that are arranged at opposite angles, calculates respectively instantaneous frequency IF (t) to bogie two ends sensor lateral acceleration signal, Zero-crossing average frequency IF _zc (t) and amplitude A _zc (t), through the instantaneous frequency IF (t), zero-crossing average frequency IF _zc (t) and amplitude A _zc (t) to calculate the nonlinear index INL , judging whether the serpentine is unstable or not by the nonlinear index INL. 2. A method for judging serpentine instability of a rail vehicle according to claim 1, characterized in that: according to the lateral acceleration signals of the sensors at both ends of the bogie, respectively extract the serpentine characteristic wave _cj , and calculate according to the serpentine characteristic wave _cj Instantaneous frequency IF(t), zero-crossing average frequency IF _zc (t) and amplitude A _zc (t). 3. A method for judging the serpentine instability of a rail vehicle according to claim 2, characterized in that: the noise-assisted EEMD empirical mode decomposition is carried out to the lateral acceleration signal of the sensor at one end of the bogie to obtain a plurality of modal components c _i ; Calculate the average frequency for each IMF And compare them with the theoretical serpentine frequency f _ci one by one, calculate ε is the error tolerance; If Δf _ci >ε, it is considered that there is no serpentine frequency component, and the EMU has no serpentine instability; On the contrary, select the modal component c _j with the smallest Δf _ci as the serpentine characteristic wave. 4. according to claim 2 or 3 described a kind of rail vehicle serpentine instability judging method, it is characterized in that: calculate instantaneous frequency IF (t), zero-crossing average frequency IF _zc (t) to serpentine characteristic wave c _j and amplitude A _zc (t); Calculate the nonlinearity index INL of the serpentine eigenwave c _j : $\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; IF</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; IF</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}}_{\mathrm{<span\; class="notranslate">\; z</span>}\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \%</span>}$ 5. A method for judging a rail vehicle serpentine instability according to claim 2 or 3, characterized in that: the nonlinear index INL is calculated respectively for the lateral acceleration signals of the sensors at both ends of the bogie, if the lateral acceleration at both ends of the bogie snakes If the frequency of the shape characteristic wave is consistent and the nonlinear indexes of both are greater than the threshold, it is considered that the EMU has a serpentine instability. 6. A method for judging serpentine instability of a rail vehicle according to claim 1, characterized in that: the method for judging serpentine instability is applied to a serpentine instability suppression system, and the serpentine instability suppression system includes The serpentine warning and control module is used to determine whether the bogie is in a serpentine instability state according to the serpentine instability determination method; Traction motor speed control system, used to control the speed of the traction motor according to the judgment of the serpentine early warning and control module; The signal output end of the serpentine early warning and control module is connected to the traction motor speed control system. 7. a kind of rail vehicle serpentine instability judging method according to claim 6, is characterized in that: described serpentine instability suppressing system also comprises lateral acceleration measurement module, is used for measuring the lateral vibration acceleration of bogie; The signal output end of the lateral acceleration measurement module is connected with the signal input end of the serpentine early warning and control module; The serpentine early warning and control module judges whether the bogie is in a serpentine instability state according to the data transmitted by the lateral acceleration measurement module. 8. A method for judging serpentine instability of a rail vehicle according to claim 6, characterized in that: the traction motor speed control system includes a given speed control module for transmitting according to the serpentine early warning and control module The control signal k and the adjusted given speed sp2 are selected to be transmitted to the speed controller module by using the original given speed sp1 or the adjusted given speed sp2; The speed controller module is used to receive the given speed and actual speed, and transmit the given flux flux ^* and given torque Torque ^* to the DTC control module; The DTC control module is used to receive the current I_ab and voltage V_abc transmitted by the traction motor measurement module, the given flux flux ^* and the given torque Torque ^* transmitted by the speed controller module, and send driving to the switching device of the traction motor inverter signal g; The control signal output end and the given speed output end of the serpentine early warning and control module are respectively connected with the control signal input end and the given speed input end of the given speed control module, and the given speed control module's given speed The output end is connected with the given speed input end of the speed controller module, the actual speed input end of the speed controller module is connected with the traction motor speed output end, the given flux linkage output end of the speed controller module, given The torque output terminals are respectively connected with the given flux linkage input terminal and the given torque input terminal of the DTC control module, and the voltage and current input terminals of the DTC control module are respectively connected with the voltage and current output terminals of the traction motor measurement module, The drive signal output terminal of the DTC control module is connected with the traction motor inverter. 9. A method for judging serpentine instability of rail vehicle according to claim 6, characterized in that: the suppression system of serpentine instability also includes a display module for displaying parameters of the serpentine instability suppression system of rail vehicle Variety; The signal input end of the display module is respectively connected with the speed controller module, the output end of the traction motor speed, and the serpentine early warning and control module. 10. a kind of rail vehicle serpentine instability judging method according to claim 7, is characterized in that: described lateral acceleration measurement module comprises sensor module, GPS module, data acquisition module, main control unit MCU module, data processing and analysis module; The data acquisition module is respectively connected with the sensor module and the GPS module, and the main control unit MCU module is respectively connected with the data acquisition module, data processing and analysis module.