时间域航空电磁法双波形发射电路研制

发布时间：2018-03-18 04:22

本文选题：航空电磁法　切入点：发射系统　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：时间域航空电磁法(Time-domain Airborne Electromagnetic Method)是一种高速有效的地质勘测方法。此方法使用直升飞机或者固定翼飞机搭载电磁发射系统和接收系统。由于航空电磁勘测可以高空飞行勘测,克服勘测地形带来的困难,所以时间域航空电磁法广泛应用在地质调查,矿产资源勘测、环境评价等方面。现阶段,国际上电磁发射系统可以提供的电流波形主要包括:梯形波,方波,半正弦波和三角波,但发射系统只可以发射一种电流波形,无法兼顾其他电流波形的优点,针对这一问题本文研究的发射电路可以提供双极性半正弦波和双极性三角波,这样可以兼顾两种发射波形的优点。本文主要参考了国际上先进的航空电磁法发射系统的发射电流参数,以此参数作为发射电流参数标准设计双波形发射电路。本文设计的发射电路结构主要包括三角波发射电路、半正弦波发射电路,开关切换电路、发射线圈四部分,三角波发射电路和半正弦波发射电路共用发射线圈,为避免两电路之间相互影响,在发射线圈与发射电路之间加入了开关切换电路。发射半正弦波的电路采用串联谐振方法,电流在电容与发射线圈之间振荡产生正弦波,半正弦波发射电路需要低压电源供电,为了兼容这一设计方案,三角波发射电路前端加入了Boost升压电路,为储能电容充电使其电压上升,由于电容容量大,三角波发射电路的功率小,充电后的储能电容可视为高压恒压大功率电源,利用此电源为发射线圈供电可以产生上升沿与下降沿线性度高对称性好的三角波。为了保证发射电路的安全稳定运行,在发射电路中加入了相应的保护电路,为了减小过冲电流,加入了去过冲电路。本文首先使用仿真软件对发射电路进行仿真测试,验证其可行性,仿真软件使用MATLAB。之后搭建电路,对电路整体进行测试,根据测试结果改进与优化电路参数,使得发射电流波形质量更高。本文叙述了设计发射电路的过程以及期间应该注意的问题,发射电路设计研制成功后,对发射电路的参数进行了测试,实际测得半正弦波电流峰值为2000A,最大输出磁矩为648000Am2,脉冲宽度为4ms,三角波电流峰值为200A,最大输出磁矩为64800Am2,脉冲宽度为1.95ms,整体的发射频率为12.5Hz,可以调整发射频率,测试结果均达到设计要求。发射电路与接收系统联机调试,接收机采集on-time信号噪声幅值与哈密地区野外飞行实验中双极性梯形波CHTEM-I系统接收磁场波形衰减曲线噪声幅值相当,所以双波形发射系统可以进行on-time采集。在最后对所完成实验工作做了总结,针对发射电路的不足之处,给出了下一步工作的几点建议。
[Abstract]:Time-domain Airborne Electromagnetic method is a high speed and effective geological survey method. This method uses helicopter or fixed-wing aircraft to carry electromagnetic launch system and receiving system. In order to overcome the difficulties caused by topographic survey, time-domain aero-electromagnetic method is widely used in geological survey, mineral resources survey, environmental evaluation and so on. At this stage, The current waveforms that can be provided by electromagnetic emission systems in the world mainly include trapezoid waves, square waves, semi-sine waves and triangular waves. However, the transmitting system can only transmit one current waveform, which cannot take into account the advantages of other current waveforms. Aiming at this problem, the transmission circuit studied in this paper can provide bipolar half-sine wave and bipolar triangle wave. In this way, the advantages of the two emission waveforms can be taken into account. This paper mainly refers to the emission current parameters of the advanced airborne electromagnetic launch system in the world. In this paper, the structure of the transmission circuit consists of three parts: triangle wave transmitting circuit, half sine wave transmitting circuit, switching circuit, transmitting coil. The triangle wave transmitting circuit and the half sine wave transmitting circuit share the transmitting coil. In order to avoid the interaction between the two circuits, a switch switching circuit is added between the transmitting coil and the transmitting circuit. The series resonant method is used to transmit the half sine wave. The current oscillates between the capacitor and the transmitting coil to produce sinusoidal waves. The semi-sinusoidal transmission circuit needs a low-voltage power supply. In order to be compatible with this design, the Boost boost circuit is added to the front end of the triangular wave transmitting circuit. Because of the large capacitance capacity and the low power of the triangle wave transmitting circuit, the energy storage capacitor after charging can be regarded as a high voltage constant voltage and high power supply. In order to ensure the safe and stable operation of the transmitting circuit, the corresponding protection circuit is added to the transmitting circuit, which can produce a triangle wave with high symmetry between the rising edge and the descending edge by using this power supply to supply the transmitting coil. In order to reduce the overshoot current, the circuit is added. Firstly, the emulation software is used to test the emitter circuit to verify its feasibility, and the simulation software uses MATLAB.After setting up the circuit, the whole circuit is tested. According to the test results, the circuit parameters are improved and optimized to improve the quality of the emission current waveform. This paper describes the process of designing the transmitting circuit and the problems that should be paid attention to during the design. After the design and development of the transmission circuit is successful, The parameters of the transmitting circuit are tested. The measured peak value of semi-sinusoidal current is 2000A, the maximum output magnetic moment is 648000Am2, the pulse width is 4ms, the peak value of triangular wave current is 200A, the maximum output magnetic moment is 64800Am2, the pulse width is 1.95ms. the overall emission frequency is 12.5 Hz. The test results are all up to the design requirements. The transmission circuit is on-line debugged with the receiving system, and the noise amplitude of the on-time signal collected by the receiver is equivalent to the noise amplitude of the attenuation curve of the received magnetic field waveform of the bipolar trapezoidal wave CHTEM-I system in the field flight experiment in Hami area. In the end, the experimental work is summarized, and some suggestions for the next work are given in view of the inadequacies of the transmitting circuit.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P631.326

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