交通信号灯防电磁干扰设计研究

发布时间：2018-10-10 13:17

【摘要】：随着生活水平的提高，人们更注重生活品质的提高。越来越多的人开始考虑购买车辆，交通压力日益严峻。传统的交通信号灯已经无法满足人们的需求，更多功能及性能复杂的交通信号灯出现在生活当中。由于其功能的复杂性，故障发生率明显提高。更多的故障来自于内部元器件，线路之间的电磁干扰。为了让交通信号灯更好的为社会服务,必须提高其抗干扰能力。本文首先概括了电磁兼容（EMC）的研究背景及国内外研究现状，详细介绍了电磁干扰三要素,干扰源，传播途径，敏感设备。抑制方法包括利用低辐射设计，电源线和信号线的隔离，设备的屏蔽,接地等，针对其干扰的不同，利用不同的抑制方法。然后通过实例CAN总线交通信号灯系统为研究对象，，利用PADS Logic软件设计其主要组成部分—CAN总线适配器原理图，对其关键部分，电源，复位电路，CAN总线，RS232接口电路等进行了详细的电磁兼容设计。在设计过程中，用到了大部分的电磁干扰抑制方法，包括接地，滤波，屏蔽等。同时对车流量测量节点的硬件等进行了电磁兼容设计。车流量检查系统用到3.3V电压，所以采用LM1804-33稳压芯片，把5V电压转换为稳定的3.3V电压。其次由于线圈传感器传递数据时，掺杂有大量的干扰信号，所正弦信号经过比较器LM393以及74HC14整形电路后输出稳定的波形，便于单片机采集。其次，利用PADS Layout绘制交通信号灯适配器PCB图，在绘制PCB时采用PADS独特的交互式布局布线方式，同时考虑电磁干扰的影响，合理设计PCB板。整体设计完毕后，利用PADS工具中的verify design来检查安全间距等规则冲突。最后介绍了集成电路正在向高速化和微型化发展，各种信号完整性问题出现在设计者面前。由Mentor Graphics公司开发的HyperLynx软件可以对PCB板信号完整性及电路实施优化,提高硬件电路的稳定性。文章中利用其子功能对过孔模型仿真，通过示波器发现过孔对电路延时，以及产生干扰等负面影响很大。所以必须采取有效的方法抑制其干扰，其次对双层板中主要存在串扰进行建模仿真。最后对整板进行电磁兼容测试，对不合理的地方改进。
[Abstract]:With the improvement of living standard, people pay more attention to the improvement of quality of life. More and more people are considering buying cars, and the traffic pressure is becoming more and more severe. Traditional traffic lights can not meet the needs of people, more functions and complex performance of traffic lights appear in life. Due to the complexity of its functions, the incidence of failures is significantly increased. More failures are due to electromagnetic interference between internal components and lines. In order to make traffic lights better serve the society, we must improve their anti-interference ability. In this paper, the research background of EMC (EMC) and the current research situation at home and abroad are summarized, and the three elements of EMI, interference source, propagation path and sensitive equipment are introduced in detail. The suppression methods include low radiation design, isolation of power line and signal line, shielding of equipment, grounding and so on. Different suppression methods are used for different interference. Then through the example of CAN bus traffic signal lamp system as the research object, using PADS Logic software to design its main component-CAN bus adapter schematic, for its key part, power supply, The reset circuit, CAN bus and RS232 interface circuit are designed in detail. In the design process, most of the electromagnetic interference suppression methods are used, including grounding, filtering, shielding and so on. At the same time, the EMC design of the hardware of the vehicle flow measurement node is carried out. The vehicle flow check system uses 3.3V voltage, so the 5V voltage is converted to a stable 3.3V voltage by using the LM1804-33 voltage stabilizer chip. Secondly, when the coil sensor transmits the data, there are a large number of interference signals, and the sinusoidal signal outputs a stable waveform after the comparator LM393 and 74HC14 shaping circuit, which is convenient for the single chip microcomputer to collect. Secondly, the PCB diagram of traffic signal adapter is drawn by PADS Layout, and the unique interactive layout and wiring mode of PADS is adopted in the drawing of PCB. At the same time, considering the influence of electromagnetic interference, the PCB board is designed reasonably. After the whole design is finished, the verify design in PADS tool is used to check the conflict of rules such as security spacing. Finally, it is introduced that integrated circuits are developing to high speed and miniaturization, and various signal integrity problems appear in front of designers. The HyperLynx software developed by Mentor Graphics Company can optimize the signal integrity and circuit of PCB board and improve the stability of hardware circuit. In this paper, we use its sub-function to simulate the perforation model, and find out by oscilloscope that the over-hole has a great negative effect on circuit delay, interference and so on. Therefore, effective methods must be taken to suppress the interference. Secondly, the main crosstalk in the bilayer plate is modeled and simulated. Finally, the whole board is tested for electromagnetic compatibility, and the unreasonable place is improved.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U491.51;TN03

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