基于运算放大器的四线法并联式电流测试仪
发布时间：2018-05-25 21:09
本文选题：电流 + 并联 ； 参考：《河北大学》2017年硕士论文
【摘要】：随着社会的智能化和科学技术日新月异发展的年代,在日常的生活和学习中越来越多接触到新的电子产品,PCB电路板构成的产品在常规检测与维修工作上成了产品检验的有力的保障。批量检测电路板的好坏和电路电流的检测技术亟待进一步简便、快捷、精准的测量。通常电流测量时需要将测量仪表串联接入电路,或者将被测导线穿过测量磁环。因此,研究一种可以与导线并联测量电流的方法,在PCB等电流测量检测等场合可带来便利,具有实用意义。本研究通过分析常见几种电流测量方法,深入分析其适用场合和测量利弊,针对目前PCB电路板在线测量的市场现象,设计了一种低成本、可以与微小阻值导线并联测量导线中电流的方法和电路。本测试电路依托运算放大器的特性和工作方式,选用具备高增益、低失调的高精度型运算放大器为核心器件,设计实现了并联式电流测量方法。此种方法改变了在传统测量PCB板电流的检测方法会在某些特定的场合给测试的带来不便,使其在PCB电路板测试检修等较小电流情况实现不需要断开PCB铜箔线条即可测量电流。本文设计给出了一种并联式电流测量电路,包括基于OP177型精密运放的主测量电路,以及由取样电阻和IRF630型VMOS管等构成的测量电流量程扩展电路。论文对电路原理进行了详细分析和仿真。对元器件的遴选进行了分析对比。采用PROTEUS对设计的电路进行了仿真验证。仿真结果表明,当被测导线阻值在≥50mΩ时,2mA~200mA范围内电流测量误差≤4%,在3mA~200mA范围内电流测量误差㩳3%。实际搭建电路中当被测导线阻值在≥50mΩ时,2mA~200mA范围内电流测量误差≤6%,在4mA~200m A范围内电流测量误差㩳2%。测试表明,该电路可以实现并联电流的测量,测量误差及变化趋势和仿真结果基本相符。主要是由于仿真的环境为理想的环境下测量而实际测量电路的时候受实验设备、环境、人为读数等诸多因素的影响。
[Abstract]:With the society's intelligence and the rapid development of science and technology, In the daily life and study, more and more products made up of new electronic products, PCB circuit board, have become the powerful guarantee of product inspection in the routine inspection and maintenance work. The quality of the circuit board and the current detection technology need to be further simple, fast and accurate measurement. Current measurement usually involves connecting the instrument in series to the circuit or traversing the measuring ring. Therefore, it is of practical significance to study a method for measuring current in parallel with conductors, which can be used in PCB and other situations. Through analyzing several common current measurement methods, the paper deeply analyzes the applicable situation, advantages and disadvantages of the measurement, and designs a low cost for the current market phenomenon of online measurement of PCB circuit board. A method and circuit for measuring the current in a wire in parallel with a small resistance conductor. Based on the characteristics and working mode of the operational amplifier, this test circuit chooses the high gain and low offset high precision operational amplifier as the core device, and designs and implements the parallel current measurement method. This method changes the traditional method of measuring the current of PCB board, which will bring inconvenience to the test in some special occasions, and make it realize that the current can be measured without disconnecting the copper foil line of PCB in smaller current condition such as PCB circuit board test and repair. In this paper, a parallel current measuring circuit is designed, including the main measuring circuit based on OP177 precise operational amplifier, and the measuring current range expanding circuit composed of sampling resistor and IRF630 type VMOS transistor. The circuit principle is analyzed and simulated in detail. The selection of components is analyzed and compared. The designed circuit is verified by PROTEUS. The simulation results show that the error of current measurement is 鈮，
本文编号：1934663
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