重庆大学
硕士学位论文
姓名：李飞
申请学位级别：硕士
专业：电气工程
指导教师：汪泉弟
2010-05
摘要现代汽车标志
伴随着现代电子技术的进步以及汽车电子技术的发展，越来越多的电子产品在汽车上得到广泛的使用，这些电子产品在增加汽车的经济性，安全性和舒适性的同时，也使得汽车的电磁兼容问题变得更为复杂，汽车电磁兼容成为现代汽车设计中必须考虑的问题。雨刮电机是为车内的重要电磁干扰源，它对汽
车的电磁兼容性有重要影响，其表现在：一方面，雨刮电机在工作过程中产生强度较高且频带很宽的电磁干扰；另一方面，车载电子设备的增多以及工作电平的不断降低，使得雨刮电机对车载设备的耦合干扰大幅增加，而且雨刮电机也是导致汽车零部件或整车无法通过相关EMC强制法规的重要原因。所以，汽车雨刮电机的电磁兼容性研究具有重大的科研价值和现实意义。本论文在国家自然科学基金项目“汽车电磁兼容预测与电磁干扰抑制关键技术研究”(编号：50877081)及重庆市自然科学基金重点资助项目“汽车电气系统电磁兼容性研究”（NO.CSTC，2006BA6015）的支持下，重点研究了汽车雨刮电机在工作过程中产生的传导干扰，辐射干扰，以及相关的抑制措施，并分别进行了仿真与实验验证，主要工作内容如下：
①对汽车雨刮系统的运行原理，雨刮电机的基本结构，以及仿真所涉及电磁场理论等进行了分析，为本文的研究工作奠定了理论基础
②对雨刮电机间歇档的传导干扰进行了仿真研究，重点分析雨刮电机的间歇档工作状态。在深入分析间歇档传导干扰产生机理的基础上，以实测获得间歇档传导干扰源—电机断开的瞬态电压脉冲；考虑绕组之间以及绕组与机壳间等分布电磁参数的影响，结合电机绕组高频等效电路模型，建立了雨刮电机传导干扰的仿真模型。在此基础上对电机间歇档的传导干扰进行仿真研究。
③分析了雨刮电机辐射干扰的产生机理及传输路径，结合信号与系统理论，通过仿真计算出的电机辐
射系统传递函数和实验测取的电机端部电压，得到整车雨刮电机电磁辐射干扰的仿真模型，从而将复杂问题得以简化处理。在此基础上对整车级雨刮电机的辐射干扰进行了仿真研究，并在重庆市电磁兼容工程技术研究中心的电波暗室进行了实验测试。仿真与实测结果取得了比较好的吻合，表明了建模方法及仿真模型的正确性。
④对常用的抑制干扰措施：屏蔽，滤波，接地进行了理论分析，由此并结合实际提出了改进雨刮电机电磁兼容性，降低其电磁干扰的有效措施。
⑤分析了铁氧体滤波器的滤波原理，考虑高频下铁氧体扼流圈分布电感及绕组间耦合电容等分布电磁参数的影响，并结合阻抗分析仪实测等效电路参数，建立了其高频等效电路模型。在此基础上，最终建立了铁氧体滤波器的高频等效电路模型。以间歇档为
例，对滤波器抑制效果仿真并做进一步特性分析。
⑥分别以高速档和低速档为例对滤波器效果进行实验测试。实验结果与仿真在趋势上及抑制特性上表现趋于一致，表明仿真及建模方法的正确性。
关键词：电磁兼容，雨刮电机，传导干扰，辐射干扰，铁氧体，汽车
ABSTRACT
With the development of modern electronics and automotive electronics technology ，more and more electronic products are widely used in cars.Although these electronic products make vehicles economic, safety and comfort , automotive EMC issues become more and more complex,.Automotive EMC must be considered in modern car’s designed The wiper system is important source in EMC to in automobile. It has a major impact to automotive EMC.On one hand, wiper motor can produce electromagnetic interference which has high and wide band during normal working time. On the other hand, Wiper Motor increase substantial interference to equipments in vehicles while electronic components and modules are widely used in automobile nowadays, and the working voltage of electronic devices gradually decrease .Wiper Motor is also an important reason that vehicle can not satisfy stringent EMC criteria.so it is has an important value and practical significance for us to research automobile EMC of window wiper system
Supported by the National Natural Science Foundation “the prediction of Automotive EMC and research to the key technologies of electromagnetic interference suppression”（NO: 50877081），Natural Science Foundation Project of Chongqing, The EMC Study of Auto Electrical System (NO: CSTC, 2006BA6015), conducted EMI and radiated EMI which is producted by wiper motor in working time, and the associated suppression measures, are considered as the focuses, then simulation and experiments are conducted, the main work is listed below:
① The principle of automotive’s wiper system,the basic structure of wiper motor, and electromagnetic theory involved in simulation, are all analyzed ,which establish the theoretical foundation to the research.
②The conducted EMI to Wiper Motor Intermittent stall is simulated .The working of intermittent stall is the key . The mechanism of generating conducted EMI in intermittent stall is analyzed deeply，and the conduction EMI source – transient pluse voltage,which productes while motor is disconnected, is measured. Combine high-frequency equivalent circuit model of motor windings when the impact of high-frequency electromagnetic parameters is considered ,the simulation model of motor conducted EMI is established On this basis, wiper motor ‘s conducted EMI in intermittent stall is predicted.
③The mechanism of radiation EMI and radiation path was analyzed , wiper motor’s
radiation EMI model in vehicle-level can be get according to calculating radiation transfer function of wiper motor and measuring the conducted voltage of wiper motor.On this basis ,the simulation to wiper motor’s radiated EMI was done in the level of vehicle.And the radiated EMI are measured in an anechoic chamber which is located in the research center of EMC, Chongqing. Simulation is consistent with experimental results ,which indicate that the modeling and the method of simulation are correct.
④ The commonly measures of suppressing EMI which is shielding, filtering, grounding are analysed, then effective measures to improve wiper motor ‘s EMC environment and reduce EMI are instructed.
⑤ The filtering theory of ferrite filters is analysed . Considering the impact of ferrite choke’s distributed inductance and winding‘s couple capacitance, which are the distribution electromagnetic parameters in high-frequency, high-frequency equivalent circuit model is established, which is combined with equivalent circuit parameters we can get by impedance analyzer .On this basis, high-frequency ferrite filter equivalent circuit model is established ,then a simulation and further characterization’s analysis are intruducted in the example of intermittent stall.
⑥Experiments to the filter is operated in the example of wiper motor’s high-speed stall and low-speed stall.The experimental is consistent with the simulation from the trend and the feature of rejection , which shows that the method to simulate and model is corrent.
Keywords: electromagnetic compatibility, DC motors, conducted EMI, radiated EMI, Ferrite ,automobile
发布评论