Research On The Key Technology Of Conducted Electromagnetic Compatibility In Electric Vehicle Driver System

With the continuous development of economy and society,environmental problems have received the attention of all countries around the world,and the requirements for environmental protection have become higher and higher.Because electric vehicle has the obvious advantage of energy conservation and environmental protection,it has a better development prospect.Power electronics are more widely used in electric vehicles than conventional ones,making their electromagnetic compatibility more complex.The most serious electromagnetic compatibility problem in electric vehicles is generated by the electric drive system,which is the main electromagnetic interference source.At present,electric vehicles are more difficult to meet the requirements of electromagnetic compatibility standard,mainly because the electromagnetic interference problem of electric drive system is too complicated.In addition,strong electromagnetic interference can endanger the safety of the car itself and negatively impact the external environment.Based on this,this paper focuses on related problems of conductive electromagnetic compatibility of the electric drive system in the electric vehicle.The main tasks are as follows:(1)On the basis of mastering the basic theory of electromagnetic compatibility and the structure and working principle of the electric drive system,this paper analyzes the mechanism of conduction electromagnetic interference of the electric drive system,and the main reason for generating the interference source is the quick conclusion of IGBT.In addition,the propagation coupling path of differential mode interference and common mode interference is studied in this paper.(2)With electric drive systems commonly used in switching power supply,for example,using current and voltage of the two kinds of typical conductive electromagnetic interference test method,respectively,measures the switch power supply under no-load and load conditions of conducted electromagnetic interference,analyzing the electromagnetic interference with the under different working conditions.Finally,the advantages and disadvantages of the two test methods of voltage method and current method are analyzed,and Suggestions are provided for the improvement of electromagnetic interference test technology.Because of the generality of these two test methods,electromagnetic interference test can be used for electric drive system or other components.(3)A method of measuring impedance with double current probes was investigated and tested.According to the research results,the impedance test method based on double current probe is more accurate than the previous impedance analyzer test method.Measured power due to the test method is a runtime impedance test,therefore,compared with using impedance analyzer test in power equipment under test conditions,this method has more real-time,and precision is more accurate.(4)On the basis of mastering the basic knowledge of immunity test and analyzing circuit impedance and the circuit current of injection,the method of laboratory testing with CDN and industrial testing method with current probes are studied.Switching power supply,for example,the correction factor is applied to the industrial environment after injection power,found the laboratory and industrial environment throughout the test frequency is very close loop current,showing a good alternative.This method can be used to establish a relationship between the test of conducted immunity in the laboratory and industrial environment,and the equivalent substitution can be achieved.This paper studies the components used in the electric drive system and verifies the correctness and versatility of the method by experiment and proves that it can be used in the test of electric drive system or other components.