【作者】 李旭；

【导师】 俞集辉；

【作者基本信息】 重庆大学 ， 电气工程， 2008， 博士

【摘要】 汽车内的干扰电磁场,主要来自发动机点火系统、发电机系统以及电动机和各种继电器触点的开闭等,而其中最强的电磁干扰源是点火系统。一方面,由于点火系统工作过程中所产生的电磁干扰的强度高,频率范围广。另一方面,随着汽车电子技术的不断发展,车载电子设备的不断增多,工作电平不断降低。这使得点火系统对车载设备的电磁危害大幅增加。所以,对汽车点火系统的电磁兼容性进行研究就具有极为重要的理论意义和工程价值。本论文在重庆市自然科学基金重点项目“汽车电气系统电磁兼容性研究”(NO. CSTC, 2006BA6015)的支持下,重点对汽车点火系统在工作过程中形成的电磁干扰进行了仿真和实验研究。主要内容如下:①基于“场—路”结合法对点火系统的传导电磁骚扰进行了仿真研究。根据点火系统各组件的电磁特性建立其等效电路模型,并运用电磁场数值法对各组件的物理模型进行计算以获得其等效电路模型所需的电参数。在此基础之上,联立各组件的等效电路模型构成了点火系统传导电磁骚扰的仿真模型。仿真和实验结果的对比,验证了方法的正确性。②基于FDTD法对点火系统的辐射电磁骚扰进行了仿真研究。以初级线缆和次级高压导线上的瞬变电压所形成的辐射电磁场为主要干扰源,通过建立适于电磁仿真的发动机点火系统和汽车整车的三维CAD实体模型,运用FDTD法对台架上点火系统的辐射电磁场,以及点火系统引起的整车辐射电磁场进行了仿真计算。仿真和实验结果的比较,证明了方法的正确性。③建立了点火系统与车内设备互连线缆间串扰问题的简化模型,提出了运用人工神经网络对串扰模型进行预测的方法。选择对串扰响应有影响的电磁骚扰参数作为输入预测因子,用基于误差反向传播的BP网络构造输入预测因子与串扰响应输出之间的映射关系,用电磁场数值法计算获得的训练样本集对构造好的BP网络进行训练,以获得串扰的BP预测模型。将串扰的BP预测结果和测试样本进行了比较,表明了该方法的有效性。并提出了相应的布线原则以抑制车内设备线缆间的串扰。④研究了汽车点火系统的辐射电磁场通过孔缝和线缆耦合对车内设备形成干扰的仿真方法。首先,运用孔缝衍射、场对线激励和含分布源传输线理论,获得了辐射场通过孔缝耦合形成对设备干扰的数学预测模型。然后,提出了一种求解辐射场通过场线耦合形成对设备干扰的等效替代模型。最后,仿真分析了辐射场的入射角度、设备孔缝的大小及连接线缆的长度对耦合干扰电压的影响。⑤对汽车点火系统电磁骚扰的抑制措施进行了理论分析,并针对部分抑制措施进行了实验测试。理论分析和测试结果表明,采用电阻型火花塞、线绕电阻型高压导线、加铁氧体及采用滤波可以有效降低点火系统的电磁骚扰。更多还原

【Abstract】 Electromagnetic interference (EMI) fields inside the automobile result from many sources such as petrolic engine ignition system, generator system, electromotor, and all kinds of relay switching. The primary EMI source is the engine ignition system. On one hand, the EMI produced by the petrolic ignition system is high intensity and has a broad-band spectrum. On the other hand, with the rapid development of automotive electronic technology, electronic components and modules are widely used in automobile nowadays, and the working voltages of electronic devices gradually decrease, it makes these devices more vulnerable to EMI. Therefore it is of great theoretical significance and practical value to investigate the electromagnetic compatibility (EMC) of petrolic ignition system. Supported by the Natural Science Foundation Project of Chongqing, China (NO. CSTC, 2006BA6015), the experiment and simulation method for the EMI of automotive ignition system is thoroughly investigated in this dissertation. The main contents are listed below:①Based on Field-Circuit combination method, the conducted electromagnetic disturbance of igniton system is simulated. According to each of the ignition system component’s electromagnetic properties to establish the equivalent circuits model for each component, and using electromagnetic numerical methods to calculate the physical model to obtain the electrical parameter for each circuit model, and then based on each circuit model to build the conducted electromagnetic disturbance model for the entire ignition system. Simulation and test results verify the correctness of the simulation.②The radiation electromagnetic disturbance of ignition system is simulated based on the finite difference time domain (FDTD) method. A three-dimensional model of the ignition system and the whole vehicle suitable for electromagnetic simulation is built using CAD techniques. Considering the transient interference current on the primary and ignition wire as the dominant radiation source and using the FDTD method, the radiation electromagnetic disturbance of the ignition system on platform, and inside the vehicle are calculated. Simulation and test results verify the correctness of the simulation.③The prediction of crosstalk coupling among interconnection wires is proposed using artificial neural networks. The input prediction features consist of those EMI parameters that have the influence on the crosstalk coupling. Using the back propagation (BP) training algorithm, the relationship between the input prediction features and the output crosstalk coupling response of the interconnection wires can be constructed. The learning sample set is obtained by the FDTD method. The effectiveness of the proposed method is verified by comparing the prediction values of the BP network and the test sample values. Finally, a wiring arrangement method is proposed for suppressing the crosstalk coupling inside the automobile.④The simulation method of the radiation EMI fields penetrating through the apertures and connection cables that interfered the electronic equipment is investigated. Based on the theory of aperture diffraction, field excitation to cable and transmission line theory with distributing source, the mathematical prediction model of the radiation EMI fields through the equipment aperture is described. Moreover, an equivalent substitution model for field to wire coupling of the radiation EMI fields coupling to the equipment external cable is presented. Finally, simulation was conducted on the impact of the incidence angle, the aperture size, and the cable length of the radiation EMI on the coupling interference voltage.⑤Electromagnetic disturbance suppressing methods of automotive ignition system are theoretical researched and some suppressing methods are also measured. Theoretical analysis and experimental results show that selection of resistor-type spark plug and ignition wire , add the ferrite and filter could reduce the electromagnetic disturbance of ignition system.更多还原