Design And EMI Analysis Of A 3.3kW On-board Charger

In face of the increasing severity of energy shortage and environment pollution,electric vehicle has become one of the effective solutions and the developing trend of automotive.On-board charger(OBC)is one of the facilities for battery charging and has the advantages of high power density and convenience for using,which makes it a necessity of electric vehicles.High efficiency and high power density are general requirements of the on-board facilities for vehicles.For this reason,the on-board charger should adopt efficient circuit topology suitable for high-efficiency operation.Electro-Magnetic Interference(EMI)standard is a compulsive requirement for a product to enter the market.However,due to the interaction of the internal circuits,the EMI effect of OBC is difficult to to analysis as well as satisfying the EMI standards.Choosing LLC converter as the main power circuit,the design of a 3.3kW OBC is fulfilled in this thesis.What's more,the electromagnetic disturbance of OBC is analyzed and discussed.Firstly,the the parameter of the LLC circuit in the charger is designed.The differential mode and common mode disturbance of OBC are also discussed.Based on the analysis,the sources of the differential mode disturbance and the common mode disturbance are pointed out.Then,the models of the passive components in the converter suitable for conducted EMI simulation are established by means of measurements.Based on the provided EMI simulation model,the equivalent circuit of the common mode disturbance of each sub-circuit is derived,as long as the simulation verification.The simulation model for the whole OBC is then obtained just combining the sub-circuits together.The comparision between the simulated and the measured EMI level of the circuit indicates that the predicted results have good accuracy before 10 M.Finally,the experimental results of the 3.3 kW OBC are presented including the key operation waveforms and the EMI performance measurements,which shows that the suppression method is feasible and the prototype meets the EMC standard.