| With the characteristics of energy saving and environmental protecting,electric vehicles have become the most promising products in the automotive industry.Unlike traditional cars,however,electric vehicles,powered by on-board power and driven by electric motors,have to deal with electromagnetic interference.With the continuous compression of the volume of components,the increasing degree of integration,and the complexity of the external electromagnetic environment,it is more necessary to analysis of the electromagnetic compatibility(EMC)of electric vehicles,the formation of the basic method and effective measures to suppress electromagnetic interference.This paper focuses on the interference research and suppression of the three-in-one assembly of electric vehicles,and analyzes the determination method of the source of electromagnetic interference,the electromagnetic crosstalk between components and the suppression problem.The main work of this paper is as follows:Electromagnetic interference analysis and modeling is carried out for on-board charger(OBC),DC/DC and power distribution unit(PDU)contained in the triad assembly to solve the conduction interference problem of each component.Firstly,the structures of OBC and DC/DC are analyzed according to the electromagnetic interference theory,and the parallel interleaving boost topology and full bridge topology are determined to meet the requirements of resistance to electromagnetic interference.An optimized average current control method is proposed to form a closed loop control circuit with voltage stabilizing effect.Secondly,according to the transmission line principle,the structure of PDU and its internal wiring arrangement is analyzed,and the interference suppression method based on frequency domain response proposed.Finally,the experimental platform of conducting interference in three parts is built,and the experimental results are compared with the simulation results to verify the correctness and effectiveness of the prediction model.Aiming at the problem of locating the interference sources in the charging process of the three-in-one assembly,a research method of finding the source of interference in reverse is proposed.Build a charging system simulation circuit composed of OBC,DC/DC and battery.The main factors affecting the output voltage stability of the charging system were determined by Monte Carlo analysis,and a large number of simulation data were processed by the principle of statistics and fitting,and Pareto statistical graph is drawn.The interference source is determined by the first few items with high values in Pareto statistical graph,and the numerical value and selection of the interfering parts are adjusted according to the fitting curve.The EMI curve is suppressed and meets the requirements of the national standard.In order to solve the problem of excessive radiation interference caused by three-in-one assembly,the radiation interference and suppression of three-in-one assembly were studied.First,the vehicle model is built.According to the principle of equivalent antenna,the external interference of the three-in-one assembly is added to the vehicle model in the form of antenna radiation,and the electromagnetic field simulation is conducted to obtain the spatial electromagnetic field distribution generated by the three-in-one assembly.Secondly,the radiation interference experiment platform of the three-in-one assembly is built to measure the radiation interference value of the three-in-one assembly,and the main frequency band exceeding the interference limit is determined by comparing with the national standard.The cross talk relation between conduction interference and radiation interference is determined.Finally,the filtering and buffering circuits are designed,and the safety capacitance is added to cover the copper foil of the device to complete the suppression of radiation interference.The feasibility of the above method of radiation interference suppression is verified by experiments. |
PDF Full Text Request