数字交流毫伏表初稿.doc

山东理工大学
毕业设计(论文)
题目: 数字交流毫伏表的设计

学院: 电子与电气工程学院
专业: 电子信息工程
毕业设计(论文)时间:二ОО九年二月日~ 六月日共十六周
摘要
在电量的测量中,电压,电流和频率是最基本的三个被测量。其中,电压量的测量最为经常。而且随着电子技术的发展,更需要测量弱电的电压,所以毫伏电压表就成为一种必不可少的测量仪器。另外,由于数字式仪器具有读数准确方便,精度高,误差小,灵敏度和分辨率高,测量速度快等特点,而倍受用户青睐。
本系统以交流毫伏表为核心,以低功耗单片机MCS-51为主控制器,通过数据采集系统采集数据,经设有运算放大电路和微型继电器的衰减模块输出,经衰减放大处理的模拟信号,其中一路信号通过真有效值直流(RMS-DC)变换,经12位快速逐次比较式A/D转换器AD574芯片转换,实时把模拟量转化为数字量;另一路信号经信号波形转换电路输出给单片机,经CPU进行计算、处理后,由七段数码LED显示出来,最终实现对被测输入信号的电压值和频率值显示测量。实际测试结果表明,本系统测量电压的频率范围100Hz~500KHz;测量电压的幅度范围100mV~100V;电压测量误差±5%±2个字;输入阻抗≥1MΩ,输入电容≤50pF;具有超量程自动报警断电功能,能有效应用于需要高精度、宽频率范围的交流电压测量等领域。
关键词:单片机,数字交流毫伏表,真有效值,智能量程转换
Abstract
In the measurement of electricity, voltage, current and frequency is the most basic measurement of the three. Among them, the voltage measurement of the volume of the most often. In addition, with the development of electronic technology, but also the need for weak measurements of voltage, so mV voltage meter has e an indispensable instrument. In addition, as a result of digital equipment to facilitate accurate readings with high precision, small error, high sensitivity and resolution to measure the characteristics of speed, and greatly favored customers.
MV of the system table to share as the core, low-power single-chip puter-based MCS-51 controller, data acquisition system through data collection, the operator has a micro-amplifier and the attenuation of the relay output module, with attenuation enlarge analog signal processing, in which the signal all the way through the DC True RMS (RMS-DC) conversion, after 12 parison fast A / D converter conversion AD574 chip, real-time analog to digital conversion for;another signal by the signal path waveform conversion circuit output to the microcontroller, calculated by the CPU and processed, by the Seven-Segment LED digital display, the ultimate realization of the measured value of the input signal voltage and frequency measurement value display. The actual test results show that the voltage of the system