Research On Conduction Immunity Simulation And Evaluation Method Based On Bulk Current Injection Technique

Bulk current injection technology is an important means to evaluate the electromagnetic interference suppression ability of aircraft electrical and electronic equipment in the conduction immunity test and evaluation system.Its test methods and test results have been widely recognized in related fields.At present,the design of airborne equipment needs to be repeatedly modified and tested before finalize production in order to meet the requirements of the corresponding immunity standard,which has the problems of long cycle and high cost.Therefore,it is necessary to build an equivalent model for the conduct immunity test process.As the model can carry out a certain "pre-experiment" in the design stage,so as to find the electromagnetic protection design defects as far as possible in the design stage,improve the efficiency of immunity test.Conducted immunity test environment is taken as research objects.Firstly,based on the lumped parameter circuit theory,the lumped parameter circuit model of the current injection probe was established,and the quantitative relationship between the geometric configuration of the current injection probe and the circuit parameters was deduced.Three typical cables,unshielded cable,shielded cable and wire harness,were selected as test cables.Combined with transmission line theory and link parameter cascading idea,an equivalent analytical model of coupling between current injection probe and interconnected cables was established,and the coupling voltage of cable terminal load was calculated.Secondly,with the help of CST’s microwave laboratory,a three-dimensional numerical simulation model of current probe and typical wiring harness was established.The simulation environment was set according to the conduction immunity test environment,and the coupling voltage of cable terminal load was calculated by using the field-circuit coordination simulation method.Then,an experimental verification platform was designed and built,and the results of mathematical analytical model and numerical simulation model were compared with the results of experimental verification to fully verify the effectiveness of the model.Finally,the immunity of different types of aeronautic cables is evaluated and analyzed,and the influences of cable laying process,terminal load and wiring harness configuration on terminal load response of cables are studied.The results show that the analytical model and numerical simulation model of the current injection probe proposed in this paper are reasonable,and both the analytical model and the numerical simulation model can accurately simulate the electromagnetic characteristics of the real current injection probe.The equivalent model of coupling between current injection probe and cable can accurately characterize the electromagnetic coupling process,and the simulation environment basically covers the requirements of conduction immunity test.Finally,the relationship between the typical laying process of aviation cables and the terminal response is analyzed,and the relevant conclusions can lay a certain research foundation for the virtual conduction immunity test.