Research On Electromagnetic Compatibility Testing Technology And Method At The Component Level Of Electric Vehicles

With the increase of battery range and the improvement of drive and control system performance,electric vehicle has become a new trend in the development of automobile industry.Power semiconductor devices have the advantages of small volume,fast switching speed and high working voltage level.They are the core components of power converter and are widely used in electronic parts of electric vehicles.However,the high-speed switching action of power devices and the arrangement of many cables of electric vehicles have brought serious Electromagnetic Interference(EMI)problems,which affect the safe and stable driving of electric vehicles.Therefore,evaluating the Electromagnetic Compatibility(EMC)performance of electric vehicle parts,and then rectifying and improving the electromagnetic compatibility design is an important measure to improve the EMC performance of the equipment.This paper mainly studies the testing technology and testing methods in EMC design.The specific works are as follows:(1)The test technologies of some EMC test sub item test and EMC test purpose are analyzed.EMC sub item tests mainly includes immunity test and emission test,which respectively evaluate the anti-interference performance of power electronic devices and the intensity of Electromagnetic Interference emitted to the outside world.For the two types of tests,the corresponding test sub item test technology and test methods are analyzed according to different coupling paths.It is pointed out that the purpose of EMC test is to evaluate the EMC performance of power electronic devices and help rectify the EMC design to improve its performance.Sub item test can provide rough direction guidance for EMC,while noise source impedance test can accurately and efficiently guide filter design and help equipment improve EMC performance.(2)The test technology of Bulk Current Injection(BCI)substitution method is analyzed.Firstly,the test steps and details of high current injection substitution method are analyzed,which is divided into two steps: probe calibration and test;Secondly,taking the Controller Area Network(CAN)as an example,it is deduced from the theoretical analysis that using different CAN cards in the test will lead to deviations in the test results,and the correctness of the theory is verified by experiments,and it is concluded that it is beneficial to improve Engineering test experience for test accuracy;Finally,according to the test results of BCI test,it is concluded that the EMI performance of the equipment to be tested is weak in the low frequency band,which provides a guiding direction for its subsequent EMC design.(3)A noise source impedance measurement method based on Line Impedance Stabilization Network(LISN)is proposed.In order to measure the noise source impedance accurately,this paper analyzes different noise source impedance measurement methods,compares their characteristics,improves the traditional double current probe method,and puts forward a new on-line noise source impedance measurement method based on double LISNs.Firstly,based on the signal transmission and signal acquisition circuits of two LISNs,the principle of measurement method is analyzed;Secondly,the noise source impedance is calculated according to the attenuation of the collected signal;Finally,the correctness of the proposed method is verified by the impedance measurement of passive devices and active devices.Compared with traditional measurement methods,this method does not use current probe,so there is no measurement error caused by energy loss caused by probe coupling,which improves the measurement accuracy and can accurately guide the design of filter.