Design And Optimization Of The Magnetics Electromagnetic Property In Power Adapter

At present,the trends of adapter power supply are high power density,small size and high efficiency.With the development of semiconductor technology,such as Silicon carbide and gallium carbide MOSFET,adapter power supply can operate at higher frequency.With the improvement of operating frequency,the high-frequency effects of transformer winding become more serious,lead the eddy loss of transformer winding increasing and decreasing the efficiency of power adapter.Therefore,it is necessary to analyze and optimize the high-frequency effect of transformer.In order to resolve the high-frequency effect of transformer windings,this paper proposes interleave building of primary and secondary winding.Based on Maxwell's electromagnetic equations,analyze transformer windings' skin effect and proximity effect,and obtain Eddy current loss of windings.Using MAXWELL electromagnetic simulation software to analyze three type structure transformers,it is indicated that the interleaving of primary and secondary can decrease the loss of winding.The interleaving of transformer primary and secondary winding could increase the parasitic capacitance of transformer,and cause the EMI common current increase.For the EMI common current,adding shield winding between primary and secondary is proposed,then carry out experiment,and the results show that when the turns and phase of shield winding is same as secondary winding,and build entire core winding width,the performance of EMI is best.Electromagnetic compatibility is an important part of adapter development.The EMI filter inductance is an effective means to suppress conduction interference,however,the performance of EMI inductance is weaken by parasitic capacitance.In this paper,two optimizations are proposed to decrease parasitic capacitance: ? winding and adding compensation capacitance,and the analysis and experiment results show that the high-frequency performance of EMI inductor has been improved significantly,and adapter obtained more EMI conduction margins.