Design And Evaluation Of A 3D Full-Wave Electromagnetic Model For Electrostatic Discharge Of Human Metals

Electrostatic discharge(ESD)is a serious source of hazard,which generates high voltage,large current and radiated electromagnetic field during the discharge process.It will have a serious impact on the life of electronic equipment or devices,and even lead to irreversible damage.Therefore,studying the discharge characteristics of human electrostatic discharge will provide a necessary theoretical basis for electrostatic protection work.Based on the current research status,firstly basing on the IEC standard ESD current waveform,a simpler expression of double exponential function is proposed,and the corresponding equivalent circuit is established.Based on the equivalent circuit,a printed circuit board(PCB)electrostatic generator controlled by mercury switch was developed,and its effectiveness was verified by time domain test;based on the IEC61000-4-2 standard,the 3ctest electrostatic gun was tested Waveform calibration is carried out,and a method for circuit modeling based on the physical structure and impedance parameters of the electrostatic gun is proposed.The simulation results in the time and frequency domains verify the accuracy of the proposed method.Secondly,a human body metal discharge model is established in 3D electromagnetic simulation software,and the material of the human body model is designed.And the parasitic parameters of the human body model are extracted,and its equivalent circuit model is established.The ESD current waveform and radiation field of the human body model are simulated by the method of field-circuit combination,and their accuracy is verified by comparing with the existing test results.Based on the established equivalent circuit model,a compact 3D electrostatic generator model based on human body and a PCB board-level electrostatic generator are designed.All of these generators can generate current waveforms based on human body metal electrostatic discharge,which can be used for practical electrostatic immunity tests.Next,a time-domain magnetic field sensor is designed for the radiation field generated by the electrostatic gun during the discharge process.A time-domain compensation method is proposed to compensate for the low-frequency compensation,and its accuracy is verified by 3D electromagnetic simulation.The radiation magnetic field generated by the 3ctest electrostatic gun under different discharge voltage levels was tested,and the radiation field generated by the switching action of the electrostatic gun was considered.Based on the method of IEC 61000-4-2,a semi-circular loop was designed.The coupling voltage of the semi-circular loop at different voltage levels was measured.During direct discharge,the radiated magnetic field is linearly proportional to the discharge voltage level.During air discharge,due to the instability of air breakdown,the repeatability of the radiated magnetic field waveform is poor.From the perspective of the rate of change of the radiation field,the discharge at the low voltage level is higher than the discharge at the high voltage level,and the rate of change of the radiation field generated by the switch action of the electrostatic gun may be higher than that of the discharge at the same voltage level.Finally,based on the magnetic field sensor,a current probe is designed.A calibration device is established in the 3D electromagnetic software,and the calibration platform is actually built.The accuracy is verified by the comparison of simulation and test results.The bandwidth of this current probe can reach 8M-1GHz,and it can be used for the test of electrostatic discharge current waveform.The designed current probe is used to simulate the discharge current waveform generated by the compact electrostatic generator model of the human body.At the same time,the discharge current waveform generated by the electrostatic gun at different voltage levels is actually tested and compared with the recovery waveform of the current probe.Through the low-frequency compensation in the time domain,this current probe can better restore the current waveform of the entire frequency band.The innovations in this dissertation are summarized as follows:1)A method for circuit modeling combined with the physical structure and impedance characteristics of the electrostatic gun is proposed,and a high-precision equivalent circuit model is established for the domestic 3ctest electrostatic gun.2)The material design of the human body model is carried out by a block method,and the designed human body model more accurately replaces the actual human body characteristics.At the same time,when simulating the radiation field of the human body model,a field-circuit combination method is used to embed the circuit model of the arc in the 3D human body model.The air breakdown discharge current and radiation field simulation results are basically consistent with the test results.3)Different from the traditional electrostatic gun with IEC standard current waveform,a three-dimensional model of the electrostatic generator is established that conforms to the discharge characteristics of the real human body,and the real object is made by using the PCB board and the mercury switch.The discharge current test results at a charging voltage of 500V are in line with expectations.