| Nowadays,fossil energy is gradually in short supply,and the damage caused to the environment by excessive use of fossil energy is also severe,the use of clean energy to replace the traditional fossil energy has become a hot research topic in the world.At present,the number of automobiles in our country is very large.In the process of using fossil energy,the traditional vehicle will exhaust a lot of tail gas containing a large number of pollution components,which will cause serious environmental pollution.Therefore,Electric vehicle(EV)emerge as The Times require.At present,all countries are strongly supporting the research and promotion of EV,and EV charger as charging equipment are also widely concerned.EV charger contains a lot of power electronic devices,DC/DC converter as one of the most important equipment of the EV charger,in the process of work,the DC/DC converter will produce strong Electromagnetic interference(EMI),EMI on the DC/DC converter and other systems in the EV charger caused serious influence,thus reducing the Electromagnetic compatibility(EMC)and reliability of the EV charger.Therefore,this paper takes the DC/DC converter in the EV charger as the research object to study the EMI caused by it.The main research contents are as follows:(1)The composition and operation mode of DC/DC full bridge converter in EV charger are analyzed.The reason of EMI source in DC/DC converter is explained in detail.The common mode and differential mode path of EMI propagation in DC/DC converter are studied.(2)The EMI prediction model of DC/DC converter is built,and the converter is modularized to establish the equivalent circuit model for each module.By combining the EMI prediction model of the converter with the equivalent circuit model of each module,the corresponding simulation circuit is built to simulate the EMI generated by the converter,and the results are compared with the corresponding EMI standards.(3)Aiming at the EMI problem of DC/DC converter,considering the three elements of EMI,for the interference source,a voltage complementary DC/DC converter with clamp diode on the primary side of the converter is designed to suppress the EMI generated by the interference source.In the aspect of EMI propagation path,based on the principle of noise balance,the main transformer in the converter is added with the inverse winding to weaken the propagation of conducted EMI.The simulation analysis of the electromagnetic conduction interference produced by the converter after adopting the suppression method is carried out,and the results are compared with those before the suppression,which shows the correctness of the suppression method.(4)The mechanism and cause of electromagnetic radiation interference in DC/DC converter are analyzed in detail,and the corresponding model of electromagnetic radiation interference in the converter is simulated.Aiming at the radiated interference of the converter,the electromagnetic shielding and floating-point grounding are used to weaken the radiated interference,and the radiated interference model of the electromagnetic shielding is simulated.Through the comparative analysis of the field strength of the sensitive circuit before and after the suppression,the suppression effect of the electromagnetic shielding is verified. |
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