岩矿石电性参数测量的精密电流编码信号发送系统  

Precise current encoding signal transmitting system for measuring electrical parameters of rock and ore

作　　者：程辉 崔峻卿[1] 付国红 傅崧原 钟湘琴[1] CHENG Hui;CUI Junqing;FU Guohong;FU Songyuan;ZHONG Xiangqin(Engineering Research Center of Advanced Mining Equipment,Ministry of Education,Hunan University of Science and Technology,Xiangtan 411201,China;Guangxi Key Laboratory of Exploration for Hidden Metallic Ore Deposits,Guilin University of Technology,Guilin 541006,China)

机构地区：[1]湖南科技大学先进矿山装备教育部工程研究中心,湖南湘潭411201 [2]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541006

出　　处：《中南大学学报（自然科学版）》2021年第3期994-1003,共10页Journal of Central South University:Science and Technology

基　　金：国家重点研发计划项目(2018YFC0603900);国家自然科学基金资助项目(42074219)。

摘　　要：针对岩矿石电性参数测量工作中电阻率跨度大、所需测量频率范围宽、存在与电流密度相关的非线性效应等问题,研发一种用于测量岩矿石电性参数的精密电流编码信号发送系统。首先,对2种电流源实现方案进行可行性分析,确定电压−电流的转换方案,并给出MCU+FPGA架构系统框图;其次,详细分析电压−电流转换电路原理,通过改进输出反馈回路获取更大的输出阻抗;第三,理论分析电压−电流转换电路,在仿真分析直流特性和交流特性的基础上,推导出电路元件的参数取值条件,并总结仿真中出现误差的原因;最后,采用阻容模型对系统的直流特性和交流特性进行实验验证。研究结果表明:系统的信号输出频率范围为1.0×10^(−3)~1.0×10^(4)Hz;输出电流范围为1μA~20 mA,并可通过精密电位器实现连续电流可调输出,驱动负载阻抗范围为10Ω~10 MΩ;系统可精确控制流过岩矿石标本的电流密度,避免非线性效应产生;信号发送系统输出直流电流稳定度相对误差小于0.5%,在测量频带内,信号发送系统交变电流输出相对误差经标定后小于0.5%。该系统基于逆重复m序列输出精密编码电流信号具有较高的输出精度,产生的逆重复m序列电流信号满足测量频率要求,适合岩矿石电性参数测量实验。Obtaining accurate electrical parameters of rock and ore was difficult,due to the large resistivity span,wide frequency range and the nonlinear effects related to current density.To address these problems,a precise current signal transmitting system encoded by the Invert-Repeated m-Pseudorandom Binary sequence(IRmPRBS)was proposed.Firstly,the feasibility of two current source schemes was analyzed to determine the voltage-current conversion scheme and the system diagram of the MCU+FPGA structure was produced.Secondly,the output feedback circuit to increase the output impedance was improved.Thirdly,by simulating the characteristics of direct current(DC)and alternating current(AC),the parameters of the circuit elements and the reasons of the simulation errors were derived.Finally,the DC and AC characteristics of the system by the resistance capacitance model were verified.The results show that the output frequency range of the system is 1.0×10^(−3)−1.0×10^(4) Hz.The output current has a range of 1μA−20 mA,which can be continuously adjusted by a precision potentiometer to achieve a load impedance ranging from 10Ω−10 MΩ.The density of the current flowing through rock and ore can be accurately controlled to avoid nonlinear effect.The output DC current stability relative error of the transmitting system is less than 0.5%,and the output AC current relative error is less than 0.5%after calibration in the measurement frequency range.The system is based on IRmPRBS,so the output coded current signal has high accuracy.The generated current signal has a frequency range that is wide enough for electrical parameter measurement and is suitable for rock and ore electrical parameter measurement.

关 键 词：逆重复m序列 精密电流源 岩矿石 电性参数 发送系统 

分 类 号：P631.325[天文地球—地质矿产勘探]