Research On The Electromagnetic Radiated Emission Of The Complete Vehicle Of Electric Multiple Unit

The radiated emission of the complete vehicle of high-speed Electric Multiple Unit(EMU)is a critical issue that determines the electromagnetic environment of the highspeed railway It is of great significance to study the electromagnetic radiated emission of the complete vehicle of electric multiple unit to improve the electromagnetic compatibility performance of EMU,and then improve the operating electromagnetic environment conditions of high-speed railway.The diversity of EMU models and the difference between the manufacturers and integrators of each component brings many difficulties in coordination.There are many radiated emission sources contributed to the radiated emission characteristics of complete vehicle of EMU and shows correlations among them,which makes the radiated emission characteristics of the EMU complex.The current research on the radiated emission of the EMU mainly focuses on the equipment of the EMU,and has not considered the EMU as a whole,so it is difficult to determine the key radiated source that causes the radiated emission of the complete vehicle to exceed the standard limit and take a global radiated emission suppression method.Both the study of the characteristics of the radiated emission of the EMU and the test verification of the effect of radiated emission suppression method need the support of on-site radiated emission test results,and one of the biggest problems the onsite radiated emission test facing is the influence of ambient electromagnetic noise,due to the interference of the ambient electromagnetic noise,it is difficult to obtain accurate radiated emission data of the whole vehicle.In view of the above-mentioned problems,this dissertation studies the radiated emission of the EMU from three aspects: the main radiated source characteristics,the on-site radiated emission test method and the radiated emission suppression method.The main research contents are as follows.(1)The main radiated sources of EMU research.According to the operation mechanism of the EMU,the dissertation studies the main radiated sources of EMU: the traction converter and the surface current of the EMU car body.Through the on-site tests,it is determined that the key radiated source of EMU which affects the radiated emission of the complete vehicle is the traction converter.The dissertation studies the electromagnetic radiated emission of the traction system and the shielding effectiveness of the equipment compartment that affects the external radiated emission level of the traction system;The dissertation studies the radiated emission characteristics of the surface current of the EMU car body.The focus is on the analysis of the radiated emission characteristics of the car body's induced surface current formed by the pantograph and catenaries off-line discharge of EMU and the over-voltage of car body during the over-phase period.It provides a theoretical reference for the study of the radiated emission characteristics of the complete vehicle of EMU and the optimization of the arrangement of sensitive equipments inside and outside the EMU.(2)The on-site radiated emission test method of EMU research.The dissertation proposes a test method of the radiated emission of the complete vehicle of EMU,which is suitable for the on-site environment.The core of the method is the ambient electromagnetic noise cancellation technology.Using the technology to process the collected radiation measurement data of complete vehicle,the method can suppress the ambient noise of data,and can receive the accurate value of the radiated emission of complete vehicle.The effectiveness of the proposed noise reduction method is verified by simulation data and on-site test data.The results show that the ambient noise can be suppressed by more than 30 d B after processing by the method.The dissertation realizes on-site measurement of the radiated emission of the EMU,and provides the necessary basis for the diagnosis and solution of electromagnetic compatibility problems of the EMU.(3)The on-site radiated emission test method of pantograph and catenaries off-line discharge research.Aiming at the problem that it is difficult to capture the pantograph and catenaries off-line discharge transient radiation by the current frequency sweep measurement method,a time-domain based test method is proposed.By constructing an optimized atomic library which is suitable for the extracting of the pantograph and catenaries off-line discharge transient radiation,the problem of poor accuracy and convergence of the existing time domain transient signal extraction method in extracting the pantograph and catenaries off-line discharge transient radiation is solved,and the accurate measurement of the pantograph and catenaries off-line discharge transient radiation on-site is realized,which provides a test solution for studying the radiated emission characteristics of it.(4)The radiated emission suppression method of EMU research.The dissertation proposes an electromagnetic radiation suppression method of EMU,aiming at the cable common mode current and car body induced surface current,which are the two main radiated sources in the EMU.The high-frequency common-mode current of the traction converter cable is suppressed by passive absorption method,and an active suppression scheme is proposed to suppress the low-frequency surface current coupled to the vehicle body by the high-voltage cable,so as to suppress the radiated emission of the complete vehicle of EMU and improve the radiated emission performance of the rolling stock from a global perspective.The research results have certain theoretical value and engineering application value for studying the radiated emission characteristics of the complete vehicle of EMU,optimizing the layout of sensitive equipment in the vehicle,and improving the electromagnetic compatibility performance of EMU.