屏蔽腔体内微带电路的电磁干扰分析

发布时间：2018-04-21 13:36

本文选题：微带线 + 非均匀FDTD　；参考：《西南交通大学》2017年硕士论文

【摘要】：随着现代电子设备的小型化、集成化,印制电路板(PCB)成为电子电气设备的重要组成部分,并且置于屏蔽腔体内,而电路板上各元器件之间通过微带线进行连接以实现信息和能量的交换;然而,由于集成电路板的尺寸日益缩小,其上所含电子元件的数目却越来越多,以至于微带线的布局更加紧凑,布线的间距越来越窄。由于强电磁脉冲的频谱越来越宽,干扰范围愈加广泛,电磁环境变得日益复杂。虽然印制电路板处于屏蔽腔体中,外界的强电磁脉冲仍然能够穿过孔缝通过PCB板上的微带线耦合进入电路,对电子元件和设备电路造成损坏和干扰。因此,分析屏蔽腔体内印制电路的电磁耦合问题具有十分重要的意义。论文首先对时域有限差分法(FDTD)的基本原理做了介绍,并结合非均匀网格划分原理和多网格集总元件FDTD方法形成一种混合算法对微带电路的电磁干扰问题进行解决,建立电磁波空间照射平行耦合微带线的电磁干扰模型,由于微带电路上的微带线和集总元件为精细结构,在计算空间的大区域采用粗网格剖分,然后在靠近微带电路的区域采用渐变步长,网格渐变到微带电路,对微带电路板部分采用细网格剖分。考虑到实际电子元件的尺寸比细网格大,即集总元件需跨过多个网格,因此,在非均匀网格基础上应用集总元件多网格FDTD算法来模拟连接的集总元件,实现微带电路板电磁耦合分析的快速计算。通过与均匀FDTD算法及商业仿真软件相比较,验证混合算法的正确性。其次,计算和分析了简单微带电路的电磁干扰特性。利用非均匀FDTD混合算法分别分析了空间电磁波极化角α、微带线线间距d、微带线线长l、微带线宽度w的变化对平行双线微带电路端接负载上耦合电压的影响。得到了自由空间里微带电路的一些电磁耦合规律。最后,现代电子设备的集成电路大都处于屏蔽腔体中,考虑屏蔽腔体对微带电路的电磁干扰影响。建立了平面波照射下屏蔽腔体内微带电路的电磁干扰模型,通过与商业仿真软件仿真结果对比验证了混合算法的正确性,然后分析了屏蔽腔体的屏蔽效果、微带线线间距d、微带线的宽度w以及PCB板的摆放位置变化对微带电路的电磁干扰影响,得到负载电阻上感应电压的变化规律,结果显示,由于微带电路结构变化导致的电磁干扰特性在自由空间里和屏蔽腔体中一致。
[Abstract]:With the miniaturization and integration of modern electronic equipment, PCB (printed circuit board) becomes an important part of electronic and electrical equipment, and is placed in the shielding chamber. The components on the circuit board are connected by microstrip wires to exchange information and energy; however, because the size of the integrated circuit board is shrinking, the number of electronic components on the circuit board is increasing. So that the layout of the microstrip line is more compact, the spacing of the wiring is becoming narrower and narrower. Because the spectrum of strong electromagnetic pulse is wider and wider, the electromagnetic environment becomes more and more complex. Although the printed circuit board is in the shielded cavity, the external strong electromagnetic pulse can still be coupled through the aperture through the microstrip line on the PCB board, causing damage and interference to the electronic components and the circuit of the equipment. Therefore, it is of great significance to analyze the electromagnetic coupling of printed circuit in shielded cavity. In this paper, the basic principle of FDTD (finite difference time-domain method) is introduced, and a hybrid algorithm is formed to solve the electromagnetic interference problem of microstrip circuits by combining the principle of non-uniform mesh generation and the multi-grid lumped element FDTD method. The electromagnetic interference model of parallel coupled microstrip lines irradiated by electromagnetic waves in space is established. Due to the fine structure of microstrip lines and lumped elements on microstrip circuits, coarse grids are used in large areas of computing space. Then, in the area near the microstrip circuit, the gradual step size is adopted, the grid is gradually changed to the microstrip circuit, and the microstrip circuit board is subdivided into fine meshes. Considering that the size of the actual electronic component is larger than that of the fine grid, that is, the lumped element needs to cross more than one mesh, the lumped element multi-grid FDTD algorithm is applied to simulate the connected lumped element based on the non-uniform grid. The fast calculation of electromagnetic coupling analysis of microstrip circuit board is realized. The correctness of the hybrid algorithm is verified by comparison with uniform FDTD algorithm and commercial simulation software. Secondly, the electromagnetic interference characteristics of a simple microstrip circuit are calculated and analyzed. The effects of spatial electromagnetic wave polarization angle 伪, microstrip line spacing d, microstrip line length l and microstrip line width w on the coupling voltage at the termination load of parallel two-wire microstrip circuits are analyzed using the nonuniform FDTD hybrid algorithm, respectively. Some electromagnetic coupling laws of microstrip circuits in free space are obtained. Finally, the integrated circuits of modern electronic equipment are mostly in the shielding cavity, considering the influence of shielding cavity on the electromagnetic interference of microstrip circuit. The electromagnetic interference model of the microstrip circuit in the shielded cavity under plane wave irradiation is established. The correctness of the hybrid algorithm is verified by comparing the simulation results with the commercial simulation software, and then the shielding effect of the shielding cavity is analyzed. The effect of the microstrip wire spacing d, the width w of the microstrip line and the position change of the PCB board on the electromagnetic interference of the microstrip circuit is obtained. The variation of the inductive voltage on the load resistance is obtained. The results show that, The electromagnetic interference (EMI) characteristics due to the structural changes of microstrip circuits are consistent with those in the shielded cavity in free space.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN03;TN41

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