Research On Electromagnetic Protection Method For Power Port Of Electronic Equipment

Power electronic equipment is very sensitive when it is impacted by lightning and surge.The transient overvoltage and large current generated by it may cause equipment components to fail after being damaged,causing immeasurable losses.In order to prevent equipment power ports and devices from being damaged by lightning,a surge protector(Surge Protection Device,SPD)is needed for overvoltage protection.Firstly,the thesis studies the physical and electrical characteristics of the gas discharge tube(GDT).Based on the simulation of PSpice software,combined with the 1.2/50-8/20μs wave impact test,a model of nonlinear resistance and voltage control switch is proposed.The GDT model also shows the comparison between the experimental test and simulation results of the voltage with time,the impulse discharge voltage,and the rise time with the impulse voltage change rate of 2k V,3k V,and 6k V.Secondly,in order to solve the problem of the cooperation style between the GDT and metal oxide varistor(MOV)in SPD under the lightning surge impact,the thesis analyzes the nonlinear volt-ampere characteristics of the GDT and the MOV.The connection model diagram of the wire at one point is established which uses the method of wave process theory.The relationship between wave impedance,current and voltage phasor is derived through the established model,and the incident,reflection,and refraction currents of MOV and GDT single devices and combined forms and their occurrence time are calculated,and the experiments and simulations are performed.The calculations were compared and analyzed.By discussing the problem of SPD coordination,the thesis designs the protection circuit model of power port of communication base station monitoring equipment and control system,which includes two parts: the first level protection circuit of AC220 V power line and the second level protection circuit of DC / DC power module,the first level protection circuit adopts three design schemes,and the three schemes are compared and analyzed from the aspects of device selection and withstand voltage capability;The twostage protection circuit adopts the composite design method of one-stage current relief and two-stage pressure relief.The transient analysis of the protection circuit,high-frequency filtering analysis in common mode and differential mode,and insertion loss analysis are carried out.The results show that the integrated protection circuit solves the problem of high current discharge between multi-level protections of power port,and has good surge suppression effect.