Research On Electromagnetic Compatibility Of High-power DC/DC Converters For Fuel Cell Vehicles

With the transformation of the automobile industry,a large number of power electronic devices are used in automobiles.T he proportion of automobile electronics in the whole vehicle is getting higher and higher,resulting in more and more serious electromagnetic compatibility problems.For fuel cell vehicles,the electromagnetic compatibility problem s are more prominent and serious due to the large number of high-frequency and high-current devices contained in the se vehicles.In this paper,electromagnetic compatibi lity of DC/DC converter,which one of the main sources of electromagnetic int erference in fuel cell vehicles,was studied.The specific research contents are as follows:(1)The geometric parameters of DC/DC converter and the experimental system were obtained by actual measurement.Then the electromagnetic radiation emission simulation model of the DC/DC converter and its connecting cable was established.The interference current data obtained by the conducted emission test was used as the Using the excitation source.The radiated electric field of the DC/DC converter was simulated and compared with the electric field strength at the reference point obtained by the radiation emission test.The results show that the error between simulation results and experimental results in high frequency i s only about 5d B,which verified the accuracy of the electromagnetic simulati on model of the DC/DC converter;(2)The crosstalk between the connecting cables wa s analyzed using the electromagnetic simulation model of the D C/DC converter that had been verified.Significant improvement was achieved,with a maximum reduction of about 40 d B under 1400 W load power,and a maximum reduction of 69 d B under 2800 W load power.In addition,the radiation immunity characteristics of the DC/DC converter were analyzed and studied.It wa s found that in the plane wave interference of30V/m～100V/m,the induced current on connecting cables was very small,only milliampere level,which would not affect the normal operation of the DC/DC converter.After adding the shielding layer,t he induced current on cable s was further reduce.It not only reduces the connecting cables to the outside electromagnetic interference,but also improves the overal l DC/DC converter anti-interference ability;(3)The radiated interference characteristics of the DC/DC converter in the vehicle environment were studied,and the surface current distribution of the metal shell of vehicle body at different frequency points was obtained.It was found that the connection cables of DC/DC converter were mainly located in the right front of the vehicle,resulting in the surface current on the metal shell of the vehicle body at the right front was larger than other parts.By observing the far field normalized direction diagram,it was found that the metal shell of the car body will hinder the electromagnetic radiation of the DC/DC converter,and the surface current on the metal shell of the car body will also cause secondary radia tion.In addition,the electric field and magnetic field intensity of the driver and passe nger head position in the car wer e analyzed.The results show that all of them meet GB 8702-2014 public exposure limit standard and would not cause adverse effects on human health.