Switching Power Supply Pcb Circuit Electromagnetic Radiation

Switched mode power supplies (SMPS) which switching frequencies extend from tens kilohertz to one megahertz can produce high frequency harmonics that may cause electromagnetic interference (EMI). EMI couples to sensitive equipments inside and outside of system with the result that electromagnetic compatibility of system was depressed.The key step of design for electromagnetic compatibility of system is realizing characteristics of interference source. This dissertation focuses on modeling technique of electromagnetic interference (EMI) for power converts of SMPS that includes following modeling works for: power semiconductors, passive component (resistance, capacitance, inductance, and printed trace), and radiated emission of three basic circuit topologies.Firstly, the component models of SMPS as the foundation were built.The printed traces were modeled as Microstrip line or coplanar stripline. High useful frequency model of PIN diode was adopted for EMI simulation, which was modeled on simulation software named Saber by using MAST program.Secondly, the SMPS model for EMI analysis was modeled on Saber and result in the time as well as frequency domain were analyzed. With the simulation result the characteristics of radiation source were researched and radiation model was built.The models of three topological circuits were given to simulate the near field of current on PCB trances, which are consisted of resistance, capacitance, inductance and diode at high frequency range. Analytical representation of the electromagnetic near field for each model was deduced from Maxwell's equations, with which software for EMC prediction can be used to predict radiation field. Radiation field of Boost SMPS was simulated and analyzed.In the end, the coupling of nuclear electromagnetic pulse to transmission line was researched.The EMP generated by a high altitude nuclear detonation can cover a continent exposing communications and other electronic equipment to a potentially damaging or functionally disrupting environment. The model of the high-altitude EMP (or HEMP) coupling to transmission line was built with the theory of transmission line. Through research, the frequency response and some conclusions were concluded.