| Aiming at the problem of coupling characteristics and protection of strong electromagnetic pulse(EMP),a double exponential nuclear EMP waveform with rising edge of 2.3±0.5ns and half width of 23±5ns is generated by the bounded wave EMP simulator.The coaxial line with different length,antenna with different angle,metal wire and magnetic ring antenna are used to couple in the electric field.Through the analysis of the coupled voltage waveform,the strong electromagnetic pulse coupling characteristics are obtained.The design scheme of protection for high electromagnetic pulse device is proposed.Surge protection device and electromagnetic pulse filter are combined for protection.The design process of EMP filter is described in detail.With the help of normalized filter,the third-order,fourth-order and fifth-order filter circuits are designed and tested in order to compare their actual effects.Finally,the PCI injection test of the strong electromagnetic pulse protection device is carried out through the electromagnetic pulse current simulation system.It lays a foundation for the research of strong electromagnetic pulse coupling and device protection.The results are as follows:(1)The voltage wave coupled by antenna and cable is bipolar wave.Before 200ns,the amplitude of oscillation is large and the frequency is higher.After 200ns,the amplitude of oscillation is small and the frequency is low.The frequency of antenna and cable coupling is mainly below 300MHz,and there are several energy peaks near 50MHz,150MHz and 200MHz.(2)The peak value of coupling voltage of coaxial cable is positively correlated with the length.The metal wire has no braided shielding layer,and the peak value of the voltage coupled to the cable is a magnitude larger than that of the coaxial cable.When the antenna is parallel to the electric field,the peak voltage is the largest,and the peak value of the coupling voltage is1.5-2 times that of the vertical field.When the electric field value is 35 k V/m,the peak value of the voltage coupled by 8.5cm metal wire is 282V and the coupling energy is 9.35×10-5J.(3)The open circuit voltage waveform of the electromagnetic pulse current simulation system tests the varistor,the transient suppression diode and the gas discharge tube.The peak value of the voltage limiting voltage of the varistor is similar to the voltage-sensitive voltage,and increases with the increase of the voltage-sensitive voltage.However,the peak voltage of the response waveform of the secondary and gas discharge tubes is not necessarily related to its own parameters,and the peak voltage is between 180-250V.The first stage SPD can use varistor and transient suppression diode in parallel,while the third stage SPD can use transient suppression diode alone.(4)The waveform and spectrum of cable coupling voltage with third-order,fourth-order,fifth-order filter circuit and without filter circuit are compared.Through the comparison,we can see that the effect of the filter circuit is obvious.Compared with the original coupling voltage peak,the coupling voltage peak is attenuated more than 50 times,and compared with only adding TVs tube,it is attenuated more than 10 times.In terms of frequency,after adding the filter circuit,the frequency is concentrated around 30m,and the frequency above 30m is partially attenuated.In the spectrum analysis,the third-order and fourth-order filter circuit is better than the fifth-order filter circuit. |
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