基于SiC MOSFET同步Buck DC-DC变换器的宽频混合EMI滤波器设计OA北大核心CSTPCD

The high dv/dt and di/dt are generated by power electronic devices,such as SiC MOSFETs and GaN MOSFETs,during power converter switching,causing serious electromagnetic interference(EMI)problems.Therefore,EMI filter design has become a hot spot in EMI research.The traditional passive EMI filter(PEF)can effectively reduce EMI generated by DC-DC converters.Because of safety restrictions on the Y capacitor,a large-volume common-mode(CM)choke is usually used to suppress low-frequency EMI.Then,active EMI filters(AEF)are efficacious in improving the power density of power converters due to their excellent low-frequency EMI attenuation characteristics.According to the high-frequency EMI attenuation characteristics of PEF and low-frequency EMI attenuation characteristics of AEF,hybrid EMI filters(HEF)have become the mainstream for EMI suppression.Because of the demand for high power density,the size and weight of the electronic components of HEF must be considered by standardizing HEF design. Firstly,an EMI model of the synchronous Buck DC-DC converter is proposed.Common-mode(CM)and differential-mode(DM)noise source impedance models are analyzed,and CM and DM impedances are determined.Then,the CM/DM noise source of the synchronous Buck DC-DC converter is measured using a line impedance stabilization network(LISN).Secondly,according to the insertion loss(IL)requirements,a hybrid EMI filter design method is proposed.Based on the EMI model of the synchronous Buck DC-DC converter,an HEF topology is selected,and the parameters of HEF components are quantitatively designed to achieve the required IL.Finally,the topologies of PEF and AEF are analyzed,and their IL is obtained theoretically.The topology and IL of HEF are studied for the filter design. The results show that CM noise dominates in the synchronous Buck DC-DC converter,and CL structure and π-type PEF structure effectively suppress CM and DM noises,respectively.The current-sensing current-compensating(CSCC)AEF is selected to further suppress CM noise based on noise source impedance and load impedance characteristics.Under selected parameter values of HEF components,the calculated passive DM IL and hybrid CM IL meet HEF design requirements.The experimental results show that the EMI noise suppression effect is better with the addition of the hybrid EMI filter,achieving an average suppression of nearly 35 dB across the frequency band(150 kHz～30 MHz).Adding an HEF into a power converter decreases system efficiency by an average of 1.24%. The following conclusions can be drawn:combined with CM and DM noise source circuit models of the synchronous Buck DC-DC converter,CM and DM impedance characteristics can be obtained.Through the theoretical analysis of IL of the HEF circuit topology,the design process of the hybrid EMI filter is presented,and the parameters of EMI filter components can be quantitatively designed.The proposed broadband design method of HEF can meet the EMC standard and improve the power density of the system,which has high engineering application value.