The Analysis Of Simulation And Experiment About EMI Of Switch Mode Power Supply PCB

Switch Mode Power Supply PCB is widely used in electronic products,its electromagnetic interference problem is getting more and more attention,the research on simulation methods for predicting the electromagnetic interference characteristics of Switch Mode Power Supply PCB is becoming more and more active.This article takes Switch Mode Power Supply PCB as the object and studies the simulation modeling methods in three different situations,in order to provide guidance for the prediction of the electromagnetic interference characteristics of power supply PCB,the specific research contents are as follows:(1)The design of DC/DC Switch Mode Power Supply PCB and simulation and experiment of near-field radiation characteristics.According to the principle of Switch Mode Power Supply,the PCB schematic diagram and circuit diagram with LM2578 as the core control device are designed,and their physical objects are obtained through board making,component welding and debugging;The simulation model is built in CST by using PCB circuit diagram,then its near-field radiation characteristics are calculated;The near-field radiation is measured by using the electric field near-field probe and spectrometer.Finally,the simulation results of near-field radiation characteristics are compared with the experimental results to verify the correctness of the simulation modeling method.(2)The design of AC/DC power supply PCB and equipment-level electromagnetic radiation simulation and experiment.The schematic diagram and circuit diagram of power supply PCB are designed with LM7805 as the core device,and the schematic diagram and circuit diagram of buzzer alarm circuit PCB are designed with LM358 as the core device,the physical object is obtained through board making,component welding and debugging,and then the two PCB and the designed shielding cavity are connected into equipment through cables;In the CST,the two PCB and the internal and external cables were modeled separately,and the simulation results of the electromagnetic radiation characteristics of the equipment were calculated and synthesized.At the same time,the test antenna was used to test the whole equipment in the microwave darkroom according to the relevant national test standard.Finally,the simulation and experiment results are compared to verify the rationality of the simulation modeling method.(3)Simulation analysis of the strong electromagnetic irradiation sensitivity for Switch Mode Power Supply PCB.The passive structure and circuit simulation model of strong electromagnetic radiation sensitivity for Switch Mode Power Supply PCB are established in CST by using the existing PCB circuit diagram;The irradiation sensitivity of resistance,inductance,and capacitance of different parameters on the PCB and the electric field response of the geometric center of the shielding shell were studied;The irradiation sensitivity of PCB connecting cables of different types and lengths is studied;The radiation sensitivity of PCB connecting cable of shielding layer with different structure,material and thickness was studied;it has guiding significance for the selection of components and connecting cables of electronic products in the environment of strong electromagnetic pulse.