Research On Immunity Test Of Cab Signalling Equipment Based On Virtual Instrument

With the improvement of train speed,train density and trainload,the locomotive power is enhanced unceasingly and traction current is also increasingly getting larger,which leads to worse electromagnetic environment.Signal equipment is vulnerable to interference in railway system.Due to signal equipment is an important guarantee for the safe operation of the railway,it is necessary to test the anti-interference ability of railway signal equipment in equipment manufacturing enterprises and railway operation sites.Considering the current needs in railway fields,Beijing Jiaotong University worked with related units to draft Technical Standards of China Railway Corporation,namely,Traction current immunity test method for railway signaling apparatus-Part Ⅱ:On-board track circuit receiving apparatus.Recently,traditionally manual test is adopted in the experiment of cab signaling equipment,which means not only heavy work,but also very difficult to put in practice and big artificial error.Therefore,the current study does some research on the following aspects:cab signal interference mechanism;test scheme of cab signal Immunity;software and hardware development of automatic test system and application verification of automatic test system.1.The thesis analyzes the mechanism that unbalanced traction current interfere to cab signaling equipment from the EMC three elements interference source;coupling channel and interference of cab signaling equipment.2.According to testing principle of unbalanced traction current from the provisions of relevant standards,the thesis determined the testing plans based on the comparative analysis three testing plans and research of the quantitative relationship among frequency,current and voltage.3.As for hardware of testing system,firstly,the overall hardware structure design of the cab signaling immunity test platform is carried out based on PXIe bus.Next,a voltage input conditioning circuit is designed for the lighting voltage of locomotive main engine.The voltage of 0-50V is linearly transformed into 0-5V voltage that can be detected by the acquisition card.Then,EMC of testing system is analyzed and designed from the perspective of grounding,electric shielding and magnetic shielding.Finally,the test precision of the system is verified.Stipulations that the performance indicators of test equipment in the standard of TB/T 3073 are as follows:The maximum deviation of frequency is ±1%;the maximum deviation of open-circuit output voltage is± 1%.and the results show that the system open-circuit output voltage error is up to 0.29%and the frequency error is up to 0.04%.4.The software of testing system is designed as a"three-tier"software structure,namely,top-layer main program,middle-layer test module and bottom-layer function module.During the process of testing,signal generator module,the host job status monitoring module and signal sample module execute in parallel and finish automatic test of each program and analyze playback of testing signal in time domain and frequency domain after testing.5.At last,after taking the testing system into practice,the test results reveal that the efficiency and accuracy of current system are greatly improved compared with the traditional testing system.