高电压比平面磁集成变压器的共模电磁干扰噪声抑制和优化设计OA

High voltage-gain-range bidirectional DC-DC converters with high efficiency,high power density,and high reliability are vital for industrial applications.The transformer of such converters often has a high turn ratio.Due to multiple magnetic components,their volume proportion and losses are high.Therefore,the converter's power density and operational efficiency are affected.Magnetic component design based on printed circuit boards(PCBs)has been widely used in isolated bidirectional DC-DC converters due to its simple winding layout,low magnetic component losses,and low-profile design.However,for high-turn-ratio transformers,the large PCB copper area on the low-voltage side winding increases the parasitic capacitance between the primary and secondary windings of the isolation transformer,providing a coupling path for common-mode(CM)noise and causing severe electromagnetic interference(EMI).Therefore,the converter's electromagnetic compatibility(EMC)characteristics are affected. From the perspective of reducing the number of magnetic components,the magnetizing inductance can be easily incorporated into the transformer by adjusting the air gap,whereas the leakage inductance is typically designed separately.Using asymmetrically distributed windings,the air-gap magnetic resistance of the center core leg can be adjusted to generate controllable leakage inductance.However,with Litz wire,the winding structure becomes more complex because the windings are wound on both outer core legs.From the perspective of CM EMI noise suppression,adding an EMI filter at the converter input is a widely used approach.The CM choke coil effectively suppresses CM noise.However,the additional magnetic components affect the system's operating efficiency and power density.For PCB winding transformers with a turn ratio of 1,a winding-cancellation technique can minimize displacement current between the primary and secondary windings by configuring the windings to have equal potential.However,for high-turn-ratio transformers,the influence of each winding's potential distribution on the winding-cancellation design requires further analysis,and the layout of the cancellation windings under high-turn-ratio conditions has not yet been studied. This paper proposes a magnetic-integrated method for a symmetrical planar transformer based on the static electric potential(SEP)point construction.Based on the integration of magnetizing inductance,leakage inductance,and high-turn-ratio transformers,the winding cancellation technology is applied to design common-mode shielding for high-turn-ratio planar magnetic integrated transformers.Consequently,the system power density is effectively increased,CM EMI noise is suppressed,and the system EMC characteristics are improved.In addition,through the optimized design of symmetrical plane-integrated magnetic components,the number of symmetrical magnetic cores is determined to achieve the lowest system loss,an equal air-gap structure,and magnetic component size parameters,which improved system operating efficiency.