Study Of Efficent Time Domain Methods For EMI Analysis Of Electronic Devices

With the development of wireless communication technology and pulse technology, space electromagnetic environment becomes increasingly complicated. The electronic devices under the complex electromagnetic environment are easily to be disturbed by the ambient electromagnetic waves. In order to ensure the safety work and better guide the electromagnetic protection design of electronic devices, a set of computation models and numerical methods is needed to be studied for the electromagnetic interference (EMI) analysis of electronic devices imminently. At present, the numerical methods used for the EMI analysis of electronic devices are still very challenging. Under such circumstances, efficient time domain hybrid methods are studied in this paper to simulate and analyze the field-line coupling problems and field-circuit mixed problems of electronic devices. Its academic contribution is briefly summarized as follows.(1) A fast calculation method for the coupling problem of long cables above the infinite ground is developed. Firstly, the crosstalk model of multiple emission lines to disturbed lines is set to analyze the crosstalk response characteristics of the loads at the terminal of disturbed lines. Then a novel fast calculation approach for excitation fields of long cables is proposed, which can avoid modeling the infinite ground directly. An efficient time domain hybrid method combined with transmission line (TL) equations, finite-difference time-domain (FDTD) method and the fast calculation approach is presented. It can be used for solving the coupling problem of long cables with hundred meters excited by ambient electromagnetic waves, and occupy less computation memory. And then the coupling principles of long cables excited by electromagnetic pulses are analyzed via this method. What's more, this method realizes the fast calculation for the coupling problem of long cables excited by multiple wideband radiation sources simultaneously. On this basis, the coupling model of shielded cables above the ground is established. The field-line coupling algorithm for shielded cables is studied. Then it is used to analyze the influence on the layer current and core wire responses of shielded cable with different grounding states.(2) Efficient time domain hybrid methods have been studied for the coupling problem of transmission lines in a shielded electronic device. Firstly, a novel time domain hybrid method combined finite integral method software with transmission line (TL) equations is proposed to simulate the coupling problem of transmission lines in a cavity with electrically large structures efficiently. Then a time domain hybrid method combined the FDTD method and transmission line (TL) equations (FDTD-TL), which can realize the rapid model of the cavity and achieve a strong synergism on the computations of space electromagnetic fields and transient responses on transmission lines. On this basis, the hybrid methods used for the coupling computations of long cables above the ground and transmission lines in cavity are modeled and packaged to form a field-line coupling effect simulation software.(3) The large-scale parallel computation of FDTD-TL method is realized. Firstly, the large-scale parallel FDTD method is studied based on the "J parallel Adaptive Structure Mesh applications Infrastructure" (JASMIN) framework. The accuracy of this method is verified by the coupling simulation of a 1kW microwave source case and a single multi-scale building. Then the FDTD-TL method combined with the large-scale parallel FDTD method is studied on the JASMIN framework to realize the parallel computation of the FDTD-TL method. Numerical examinations have verified the accuracy and efficiency of this parallel method. And then it is used to analyze the coupling properties of the electromagnetic leakage from the magnetron of the high power microwave source to internal transmission lines.(4) The coupling effects and electromagnetic protection of lumped loaded linear antenna excited by electromagnetic pulses are studied. A novel lumped element FDTD method with lumped elements in the FDTD grids is proposed, and combined with the fine wire FDTD method to simulate the coupling problem of the lumped loaded linear antenna. The influences on the current responses of the antenna by different types and pulse widths of ambient electromagnetic pulses are analyzed. It can provide theoretical foundation for the electromagnetic protection design of the antenna. Then a front door protection module is designed for the electromagnetic protection of a VHF antenna working in 50 MHz to 110 MHz. The circuit simulation software is used to design the filter circuit and protection module circuit. Then the physical objects of these circuits are produced for test to make them meet the requirements of indicators.(5) The novel time domain field-circuit hybrid methods applied for the EMI analysis of electronic devices are developed. Firstly, a novel hybrid method combined the FDTD-TL method with the circuit analysis method has been developed for the EMI analysis of penetrative lines terminated with lumped circuits in electronic device. In which the equivalent circuit models of the penetrative lines under excitation are extracted with Thevenin's theorem. Using the state variable approach with FDTD method, the EMI of the internal lumped circuit has been efficiently analyzed. Numerical examinations have verified the validity of this hybrid method and also demonstrated its capability for EMI filter protection design of the penetrative lines with the electronic device. Then an efficient hybrid method combined the novel time domain S parameter cascade (TD-SC) technique with the FDTD-TL method has been developed for the EMI analysis of transmission line network in electronic device. According to TD-SC technique, the transmission line network is decomposed into transmission lines and circuits. The effects of circuits to transmission lines are equivalent to the S parameters of circuits. Then the FDTD-TL method is used to obtain the transient responses on the transmission line network. The accuracy and efficiency of this hybrid method have been verified via several numerical examinations.