【作者】 张宏侠；

【导师】 李青侠；

【作者基本信息】 华中科技大学 ， 电磁场与微波技术， 2007， 硕士

【摘要】 随着我国国民经济的不断进步和科技现代化的飞速发展,对汽车安全性提出了越来越高的要求。为此,我国自主研制和发展高性能、高可靠性的TPMS,其意义和影响非常深远。但目前国内研制的TPMS普遍存在稳定性和可靠性差的问题。影响信号传输的稳定性和可靠性的因数有很多,无线信号传输的稳定性是主要原因之一。本文针对该问题,研究TPMS射频系统,包括:1)TPMS发射、接收天线的建模及仿真。针对发射天线,提出动态天线的概念,定义动态天线由无线传感器天线、轮毂、车身、地面组成,同时建立了动态天线仿真模型。针对接收天线,建立车内接收天线天线模型,主要考虑车体对接收天线性能的影响。仿真结果显示:TPMS发射天线、接收天线不再保持各向同性,引起传输功率的起伏变化;他们各自方向图存在一些零点,这说明它们在某些方向上不辐射功率和不接收功率,将导致有时接收不到信号;发射天线的阻抗实时变化,这将给发射机的功率放大器和天线匹配带来问题。2)TPMS射频发射、接收电路的设计。TPMS的发射和接收电路采用模块化设计。重点讨论发射机动态天线匹配电路设计,本文采用了一种简单有效的折中方案来解决发射天线阻抗的实时变化给发射机的功率放大器和天线匹配带来的问题,即:取240°点阻抗来进行阻抗匹配设计,仿真结果显示其端口回波损耗在12~36dB之间变化,证明这种匹配方案是可行的。3)针对新设计的TPMS系统,给出了三种测试方案,即静态功率传输测试、动态数据传输测试和实际使用环境测试,来对新的TPMS系统性能进行评估。试验结果显示:采用新方案设计的TPMS系统,其信号功率传输提高了20~30dB;数据帧传输的正确率由61.4%提高到97.8%;满足实际使用的需要,证明新设计的TPMS系统性能有大幅度的提高。更多还原

【Abstract】 With the continuous progress of national economy and the rapid development of modern technology, the demand for car safety is increasing. So it is more significant for us to develop the TPMS with excellent performance and reliability by ourselves. However, now the stability and reliability of TPMS developed by our country is very poor. There are many reasons for the poor performance of signal transmission, but the un-stability of wireless signal is important one.This paper is focusing on the RF system of TPMS, the content is as below:1)Modeling and simulation of transmitter antenna and receiver antenna of TPMS. For the transmitter antenna, a dynamic antenna concept is introduced, which consists of a wireless sensor antenna, four wheels, and car structure; for the receiver antenna, a model used, which considers the influence of car body. The model of dynamic antenna is presented. The simulation results show the radiation of the receiver antenna and transmitter antenna is not the same on all the directions. This means that the transmission power will vary along the time; there are many nulls on the radiation pattern of the receiver antenna and transmitter antenna and there are no radiation power on these nulls, so the TPMS can’t receive the signal sometimes. At the same time, the resistance variation will introduce some difficulties for the matching between power amplifier and transmitter antenna.2)The circuit design of TPMS transmitter and receiver. The TPMS transmitter and receiver are designed by adopting special integrated circuit modules. we focus on the design of the matched circuit of transmitter dynamic antenna, a simple and practical matching case between power amplifier and transmitter antenna is presented to solve the problem due to the resistance variation of the dynamic antenna, that is, the resistance on the 240°is used to design the matched circuit. The simulation results show that the return loss of the antenna port varies between 12dB and 36dB. This proves that this case can be used for the matched circuit design.3)In order to test the system performance of new TPMS, three test methods are presented, that is, static power transmission test, dynamic data transmission test and real environments test. The test results show: for the new TPMS, the power of wireless signal transmission is increased about 20~30dB; the frame correct rate of receiving data is increased from 61.4% to 97.8%; the results of real environments test show that the frame correct rate of receiving data meets the requirement of the TPMS; these proved that the system performance of the new TPMS is improved greatly.更多还原