大功率井—地电磁发射机远程外控技术研究

发布时间：2018-04-07 17:58

本文选题：频率域电磁发射机　切入点：DDS　出处：《中国地质大学(北京)》2017年硕士论文

【摘要】：井-地电磁勘探是一种有效的金属矿勘查方法,利用矿区己有的矿洞与巷道,采用井中发射、地表接收的方法,能有效地避免地表电磁干扰,增加勘探的精度。相对于传统的电磁发射机,本课题设计的井-地电磁发射机,采用了分体式远程控制的方案,即将发射机的控制模块与主回路分开,通过多芯屏蔽线缆连接。这种做法有诸多优点,其中最显著的是可以避免高压部分对低压控制部分的电磁干扰。本文主要介绍井-地电磁发射机中的低压控制部分的硬件电路和软件设计。本文所设计的电磁发射机主要应用CSAMT方法,发射频点范围为1OkHz～0.01Hz。传统频率域电磁发射机存在频点覆盖率低、在野外环境工作效率不高和同步发射性能差等问题。根据课题研制的发射机的技术指标要求,本文采用直接数字频率合成技术(DDS)与复杂可编程逻辑器件(CPLD)设计实现了发射机任意频率的供电波形合成功能;利用CPLD强大的逻辑运算能力,在常见的扫频功能的基础上增加了一种简单可靠的多频发射波形,提高了野外电磁勘探的工作效率;利用结合GPS信号的恒温晶振校准电路,设计实现了发射系统的高精度同步发射。概括而言,控制系统是以ARM+CPLD作为主控,外围电路主要有DDS、RTC、恒温晶振校准电路和无线模块等。系统中的软件设计主要包括频率表定时扫频程序设计、波形合成程序设计和发射脉冲与PPS信号同步程序设计,其中波形合成程序包含有单频、多频和m序列供电波形三种波形的程序设计。最后,系统进行了多次水槽试验和野外试验,其中水槽试验主要进行了发射机的供电波形测试、同步精度测试和上位机程序测试等,野外试验则主要测试了发射机的整体工作性能。结果表明,发射机合成的发射波形频点精度高、频率稳定性好、多频信号能量分布均匀、发射同步误差在纳秒级、死区时间设置合理,发射机长时间工作稳定,系统可靠性高,完全满足课题设计要求。
[Abstract]:Well-ground electromagnetic exploration is an effective method for the exploration of metal deposits. Using the existing mine holes and roadways in the mining area, adopting the method of in-hole launching and surface receiving, can effectively avoid the surface electromagnetic interference and increase the precision of exploration.Compared with the traditional electromagnetic transmitter, the well to ground electromagnetic transmitter designed in this paper adopts a separate remote control scheme, that is, the control module of the transmitter is separated from the main loop and connected by multi-core shielded cable.This approach has many advantages, the most significant of which is to avoid the electromagnetic interference of the high voltage part to the low voltage control part.This paper mainly introduces the hardware circuit and software design of low voltage control part in well-ground electromagnetic transmitter.The CSAMT method is mainly used in the electromagnetic transmitter designed in this paper. The frequency range of the transmitter is 1 OkHz0. 01 Hz.The traditional frequency domain electromagnetic transmitter has some problems, such as low frequency coverage, low efficiency in field environment and poor synchronous emission performance.According to the technical requirements of the transmitter developed in this paper, direct digital frequency synthesizer (DDS) and complex programmable logic device (CPLDD) are used to design and realize the power waveform synthesis function of the transmitter at any frequency.By using the powerful logic operation ability of CPLD, a simple and reliable multi-frequency transmitting waveform is added on the basis of common frequency-sweeping function, and the work efficiency of field electromagnetic exploration is improved, and the calibrating circuit of constant temperature crystal oscillator combined with GPS signal is used.The high precision synchronous launch of the launch system is designed and realized.To sum up, the control system is based on ARM CPLD. The peripheral circuits include DDS RTC, constant temperature crystal oscillator calibration circuit and wireless module.The software design of the system mainly includes the frequency table timing sweep program, the waveform synthesis program and the synchronous program of transmitting pulse and PPS signal, in which the waveform synthesis program includes single frequency.Program design of multi-frequency and m-sequence power supply waveforms.Finally, the system has carried out many water tank tests and field tests, in which the water tank test mainly carried out the transmitter power supply waveform test, synchronization accuracy test and host computer program testing, etc.Field tests mainly test the overall performance of the transmitter.The results show that the transmitter has the advantages of high frequency accuracy, good frequency stability, uniform energy distribution of the multi-frequency signal, the synchronization error in nanosecond level, reasonable dead-time setting, stable work for a long time, and high reliability of the system.Fully meet the project design requirements.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P631.325

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