EMC Characteristics Analysis And The Model Research Of Electric Vehicle Traction Battery

Domestic automobile industry has made great progress in recent years, but thestudy of automotive electromagnetic compatibility is still lagging behind. In recentyears, environmental problems highlighted. Electric vehicle is an important way toalleviate the problem. So the related technology needs further breakthrough. In view ofthe present research status of domestic automobile electromagnetic compatibility, thispaper researched the EMC characteristics of the traction battery, which is the mainelectromagnetic interference coupling node of electric vehicle. This article embarksfrom the EMC characteristic of traction battery, and typically researched the frequencymodel of batteries’ ac impedance characteristics, and then applied it to the EMC modelof vehicle. The main research contents are as follows.1) The main interference sources and coupling paths of high voltage system werefound through the simulation of practical work of electric vehicle’s high-voltageelectrical system: The main interference source of the EV high voltage system isthe motor controller and the DC/DC converter. Traction battery is directlyconnected with the DC/DC converter and the motor controller, and thus becomethe coupling path for the interference. Impedance characteristical of tractionbattery directly affect the propagation of interference.2) The analysis and research on the impedance spectroscopy of traction battery madethe factors in each domain clear. And this paper established models of battery ineach domain. At low frequencies (about some mHz)，impedance measurementsmainly show the mass transport effects. As frequency increase, the effect ofpolarization become to make difference. The skin effect shows an influence atfrequencies of above several kHz.3) As for the running condition of EV, this paper analyzed the influence oftemperature, battery aging and state of charge on battery impedance. And alsoestablished the function equation of different correction factor so as to constructbattery models under different factors.4) As for conducted interference, this paper studied high-frequency models ofbattery by different meathead. Based on frequency domain analysis, highfrequency mathematical models of batteries was established. And based on timedomain analysis, this paper constructed high-frequency circuit models of batteries. What’s more, based on vector fitting meathead high-frequency circuit models ofbatteries were also built. The correction of models were verified by thecomparison of model values and measured values. In the end different modelswere analyst and compared.5) This paper discussed the application of battery impedance model in vehicleelectromagnetic compatibility simulation. And a method of getting interferencesource was introduced. Couping interference model of the traction battery wasestablished and simulated in Saber, and the results were analyst in time andfrequency domain.