小电阻精确测量系统设计毕业设计word格式.doc

毕业设计（论文） 题 目：小电阻精确测量系统设计 学 院：电气与电子工程学院 专 业： 电子信息工程 学生姓名： 指导教师： 毕业设计（论文）时间：二〇一〇年三月一日～六月二十日 共十六周摘 要 在电路测试过程中常常会碰到由于忽略某些小电阻的影响引起实验数据与理论值之间存在较大误差的情况，从而影响测试效果。例如电感器、变压器中往往存在铜电阻，地铁铁轨的电阻，扬声器连接线的电阻，过电流保护电路中的检测电阻等。所以测量这些小电阻是电子测量中的一个常见课题。 由于小电阻数值较小，一般的指针万用表无法测量出来；通常实验室里会用电桥进行测量，但电桥操作手续较烦，又不能直接读出被测电阻阻值。鉴于此，我们采用了MSP430F149单片机作为控制核心，利用单片机的优势设计了该测量系统。该测量系统可直接从LED数码管上读出所测得的电阻值，测量范围从几mΩ到1Ω之间，同时可以把测试的数据进行储存，然后经串行口送入上位机，通过上位机的强大功能，可以对所测得的数据进行分析、处理。该测试仪的测量精度高达±0.05%，并采用四端测量法，电阻值不受引线长短及接触电阻的影响。不仅测量简便，读数直观，且测量精度、分辨率也高于一般电桥。可用于实验室、研究所，尤其适用于工作现场。 关键词: 四端测量法，小电阻，恒流源，MSP430系列单片机 Abstract In the circuit the testing process often encountered little resistance as the impact of neglect caused by some experimental data with large error between the theoretical value, and thereby affect the testing results. For example, inductors, transformers, there is often copper resistance, the resistance of the MTR tracks, the speaker cables resistance, over-current protection circuit in the detection of resistance and so on. Therefore, measuring the small resistance is a common electronic measurement topic. As the low resistance value smaller pointer multimeter to measure the general out; usually will power the laboratory to measure the bridge, but bridge over trouble operating procedures, can not directly read the measured resistances. In view of this, we use a MSP430F149 microcontroller as the control, using of the advantages of single chip design of the measurement system. The measuring system can control directly from the LED digital read out the measured resistance value, measuring range from a few mΩ between1Ω, while the test data can be stored, and then into the PC via serial port, through the PCs power, can be measured by the analysis of the data, processing. The testers measurement accuracy up to ± 0.05%, and the use of four-terminal measurement, the resistance from lead length and contact resistance. Measured not only simple, intuitive readings, and measurement