Analysis Of Main Leakage Magnetic Field Of Traction Traveling Wave Under Fault Condition Of High Speed Maglev Long Stator And Design Of Detection System

With the popularization and application of high-speed maglev train,the importance of its track gradually highlights.The particularity of high-speed maglev track is that it is a long stator of synchronous linear motor,which generates a traveling wave magnetic field to pull the train forward.The abnormal condition of the long stator,such as irregularity,cracking of the epoxy layer on the surface of the core,short-circuit between the core pieces,and damage or suspension of the traction cable may cause changes in the traveling wave magnetic field,affecting the running stability,safety and comfort of the train.Faced with the long-distance laying of track,a method of rapid judgment and positioning of the mounted high-speed maglev track fault is needed to improve the maintenance efficiency of the traffic.This paper focuses on the performance and detection method of traction traveling wave main leakage magnetic field under different abnormal conditions of long stator track.Firstly,in order to explore the behavior of the main leakage magnetic field of the traction traveling wave under different stator anomalies.In this paper,based on the analytical calculation method,it is concluded that the amplitude of the main leakage magnetic field of the traction traveling wave decreases with the increase of the hanging distance when the stator cable is hung,and the eddy current is affected when the stator core is short-circuited.However,when the stator segment is obviously deformed,the increase of the detection distance shows a large gradient attenuation.In addition,the finite element method is used to simulate and analyze the long stator track model.By setting different abnormal conditions,the performance law of traveling wave main leakage magnetic field is explored.The conclusion of the two methods is consistent,which provides a theoretical basis for judging the track anomaly based on traveling wave main leakage magnetic field detection.In order to realize the dynamic detection and judgment of the abnormal condition of the main leakage magnetic field of long stator traveling wave,a ‘2+1' detection method is proposed in this paper based on the analysis and simulation method.Aiming at the synchronous operation of the magnetic sensor with the main leakage magnetic field of the traction traveling wave,a "time domain self-comparison method" based on single Hall sensor is proposed;Considering the fixed relative position relationship between sensors in array layout,a "phase comparison method" based on Hall sensor array is proposed;Both methods can independently realize the magnetic field abnormality detection.In view of the fact that the non-uniform inter-chip short circuit anomaly of the core will break the symmetry of the traveling wave main leakage magnetic field in the direction of the core superposition,a "symmetric detection method" based on the symmetry of the transverse magnetic field of the stator is proposed to assist in detecting the short circuit between the core pieces and the lateral displacement of the track.The effectiveness of the above detection methods was verified by experiments and simulations.In order to realize the dynamic detection of abnormal conditions of long stator orbits,a scheme of long stator orbit anomaly detection system based on traveling wave main leakage magnetic field detection is proposed.In view of the weak signal of abnormal magnetic field and the existence of many external disturbances,this paper proposes to reduce the inherent measurement error of magnetic sensor,reduce the high-frequency interference of the detection system by chopper,the inherent white Gaussian noise of electronic system and magnetic flux leakage of suspended magnetic field by means of temperature compensation,low-pass filtering and cross-correlation filtering.Therefore,the anti-interference and signal-to-noise ratio of the magnetic field detection system are improved.Aiming at the problem of benchmark deviation caused by train vibration under dynamic detection mode,the vertical clearance change is detected by laser displacement sensor in real time,and the magnetic field measurement result is compensated by clearance data,which eliminates the influence of vibration.In addition,the abnormal condition of the long stator is often accompanied by the change of the stator temperature.The system uses the infrared sensor to detect the surface temperature of the long stator,and assists the detection of the abnormality of the long stator.