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1、Classified Index: TP273U.D.C: 681.5Dissertation for the Master Degree of EngineeringSTUDY ON FAR FIELDELECTROMAGNETIC RADIATION MODELAND SIMULATION OF A FLYBACK POWERSUPPLYCandidate： Supervisor：Academic Degree Applied for：Speciality：Affiliation：Date of Defence：Degree Conferring Institution：Kejian Ji
2、 Asso. Prof. Junping HeMaster of EngineeringElectrical EngineeringShenzhen Graduate SchoolDecemeber, 2010Harbin Institute of Technology哈尔滨工业大学工学硕士学位论文摘要开关电源在工作过程中会产生高幅值、快变化的电流和电压，不仅会在其周围产生强烈的电磁干扰(EMI)，还会通过导线将辐射向远处发射出去。该远场电磁辐射常会对周围其它无线电电路的正常工作产生不良影响、也易造成辐射发射认证测试失败。因此对开关电源辐射辐射特性进行研究具有重要的理论意义和实际应用价值。本文
3、对一台单端反激开关电源的远场电磁辐射机理进行分析，建起简化辐射模型，并对其辐射特性、影响因素及作用进行了仿真、具体考察了远场电磁辐射的影响因素及作用。本文主要研究内容如下：(1) 在电子设备远场电磁辐射干扰机理分析的基础上，针对反激开关电源实际结构，分析了其远场电磁辐射干扰发射的特点和基本机理。高频开关状态下的开关管产生高幅值、快变化的电压、电流，其产生电磁辐射源并通过导线发射出去。(2) 辨识反激开关电源远场电磁辐射的影响因素，即导线放置方式、导线长度、电网阻抗特性以及地平面等因素。提取出反激开关电源远场电磁辐射发射简化模型，并利用有限元仿真软件 Ansoft HFSS 建立反激开关电源远场
4、电磁辐射 3D 仿真模型。(3) 建立了不同条件下的远场电磁辐射模型，进行仿真，得到方向图和场强图的仿真结果，并分析其对远场电磁辐射特性不同的作用。(4) 对简单激励条件下，导线的远场电磁辐射进行实测，并通过实测与仿真的比较对模型进行初步验证。本研究有助于帮助设计人员认清远场电磁辐射的规律，指导电源 EMI 设计，继而降低开关电源辐射干扰发射，促进开关电源早期的 EMC 设计。关键词：开关电源；远场电磁辐射；有限元仿真；RFI 预测-I-哈尔滨工业大学工学硕士学位论文AbstractThe current and voltage, whose amplitudes are high, and
5、rates of changes are fast, will be produced, when the switching-mode power supply(SMPS) is working. The current and voltage, whose amplitudes are high, and rates of changes are fast, can not only produce strong EMI problem around the circuit, but also emit out through the cables which add to the PCB
6、. The far field radiation uaually interfer the other radio circuit which is around it, and the radiation will produce RFI filture. So it is important to study the Far-field radiation mode of the SMPS. It will have theoretical and practical use. In this paper, the Far-field electromagnetic radiation
7、mechanism is studied among a Flyback power supply, and the model of the Flyback Power Supply is bulit up. Anter that, the radiation characters and effectors are also simulated and studied. In this paper, the main works of this paper as follows: The far field electromagnetic radiation interference me
8、chanism in electronic circuit is introduced, the character and mechanism of a actural Flyback power supply is analyzed. The High amplitude and quick changes voltage and current will produce Electromagnetic Interference, and the interference will emit out by the cables. Some effecters of the SMPS rad
9、iation are identified, such as the length of cables and the position of the cables and the impedance between L/N and PE and the earth. A simple radiation model of Flyback power supply is bulit, and a 3D model is bulit in Ansoft HFSS. The factors, such as the position of the cables, the length of the
10、 cables, the impedance of the cables and the ground etc, are studied. And the models under different condiction are builed. The effects are also studied. Different experiments are designed under different condiations with a simple exciation. The results of the simulation are compared with the experi
11、ments, and the feasibility is verified. The paper will help designers get a clear understanding of the nature of electromagnetic radiation, to guide EMI design of SMPS, then reduce radiated interference and for EMC early to provide a reference for design.Keywords: switching-mode power supply, far-fi
12、eld electromagnetic radiation, FEM simulation, RFI prediction-II-哈尔滨工业大学工学硕士学位论文目录摘要 . IAbstract.II目录 . III第 1 章 绪 论 . 11.1 课题的研究目的及意义. 11.1.1 研究目的 . 11.1.2 电磁辐射的危害 . 21.1.3 研究意义 . 21.2 开关电源远场电磁辐射国内外研究现状. 31.2.1 远场电磁辐射干扰的背景 . 31.2.2 开关电源远场电磁辐射仿真研究的国内外现状分析 . 41.3 本文主要研究内容. 7第 2 章 单端反激开关电源及其远场电磁辐射机理分析 . 82.1 单端反激开关电源及其辐射发射. 8 2.2 电子设备远场电磁辐射主要原理. 102.3 单端反激开关电源远
