| With the development of science and technology,people's life has entered the information age,and power electronic technology has been widely used in various fields.And power electronic technology is constantly developing towards high frequency,high speed,miniaturization and integration.With the continuous improvement of power electronic technology,a large number of modern power electronic devices are used in electronic equipment such as computers and switching power supplies to strive for high frequency,high speed and miniaturization,and the electromagnetic compatibility problem brought by this is also becoming more and more prominent.Therefore,it is very important for circuit designers to analyze and optimize electromagnetic compatibility characteristics in the process of circuit board design.In this thesis,a flyback switching power supply circuit board is taken as an example to study the electromagnetic compatibility characteristics of the circuit board.Firstly,this thesis briefly analyzes the basic structure and working principle of switching power supply,analyzes the working methods,advantages and disadvantages of several common topology structures of switching power supply,and analyzes the two feedback control modes of voltage control and current control of flyback switching power supply.The mechanism of electromagnetic interference of flyback switching power supply is analyzed.Secondly,the main interference source of the flyback switching power supply is determined through analysis,and the acquisition method of the high-frequency parameter model of the devices involved in the simulation and the acquisition method of the interference source excitation are determined.For the high-frequency transformer,the simulation model cannot be accurately established in the Power SI simulation software.For this practical problem,the field-circuit combination method is adopted,that is,the excitation waveform of the high-frequency transformer is obtained from the circuit point of view with PSpice software,and then the electric field radiation intensity and magnetic field radiation intensity are simulated in the Power SI software.Thirdly,the electromagnetic radiation simulation model of the circuit board is established in Power SI software,and the electric field radiation intensity and magnetic field rad iation intensity at different frequencies are obtained by simulation.By applying external interference,the sensitive frequency of the switch tube and the induced voltage of the pin at different frequencies are obtained by simulation;Finally,several methods commonly used in electromagnetic compatibility design are analyzed,and based on the principles of electric field coupling and magnetic field coupling,the layout of the circuit board is optimized,and the optimized circuit board is simulated and analyzed.The results show that the optimized circuit board has better electromagnetic compatibility,which verifies the effectiveness of the method. |
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