直流电法仪的研制
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摘要
电法勘探属于地球物理勘探领域，直流电阻率法是电法勘探的一个重要技术方法。它以地壳中地质体的电性质差异为基础，研究在人工施加激励电流的条件下，直流电场的空间分布规律，达到勘查资源和查明地质构造的目的。直流电法仪是应用直流电阻率法的勘探装备，包括测控主机、数据解释软件及电极、线缆等辅助设备。本文针对直流电法仪的测控主机部分，设计了一套采用车载蓄电池供电，将发射系统、接收系统、主控系统连同电源变换系统集成为一体的电法测量设备。
系统使用开关电源从蓄电池取电，得到高压直流信号，然后经过H桥电路形成正负相间的低频方波激励信号，并通过发射电极向地下发射。发射机和接收机分别检测发射电极中的发射电流和接收电极中的接收电压，由微控制器C8051F060对调理后的信号进行A/D采集，然后将测量结果通过RS-232C串口传输给PC机，由PC机完成数据的存储和处理工作。
仪器的电源系统方面，分别采用移相控制全桥软开关脉宽调制DC-DC变换器、Boost升压电路和负压电路、线性稳压电路等方案，以满足相应的400V高压、±15V及5V和3.3V等直流稳定电源的需求。其中移相全桥直流-直流变换器中，采用集成PWM控制器UCC3895组成控制电路，Boost升压电路采用集成直流-直流变换器MC34063作电路核心。仪器的控制系统应用PC机作上位机和微控制器作下位机的两级控制思想，PC机负责设置测量参数和命令，存储和处理测量数据等工作，微控制器C8051F060根据上位机设定的测量命令，完成对测量主机的控制和数据采集工作，两者通过RS-232C串口进行通信。
系统在提高测量精度，优化工作性能和增强稳定性方面作了许多工作。在电源方面，系统工作电源分为数字电源和模拟电源，同时数字地和模拟地分开，并采用一点接地方式，以降低数字电路对高精度模拟电路的干扰。控制系统中，微控制器通过光耦和被控制部分进行隔离，以降低功率电路对控制电路的影响。在激励信号方面，采用正负相间的低频方波信号，并在激励电流为零时测量自然电位，在激励电流不为零时，测量一组相反的激励电位，然后通过后续的数据处理，消除大地自然电位和电极极化电位差对测量结果的影响。在信号检测方面，采用霍尔电流传感器对发射电流进行隔离检测，以规避采用电阻采样法对被测系统的影响；在接收电压检测时，采用两级程控增益仪用放大器组成前置放大器，以抑制共模干扰，提高信噪比，并把被测信号放大到ADC的最佳量化区间，同时加入50Hz陷波电路，以抑制仪器在野外工作时常见的工频干扰。另外，系统的元器件均选用工业级工作温度，整个测量主机集成在同一个箱体中，以提高仪器在恶劣条件下的工作稳定性。
Electrical prospecting belong to the field of geophysical prospecting, and the DCresistivity method is an important method of electrical prospecting. Based on thedifference of the electrical properties of crustal geological, it research space distributionof the underground DC electric field under the artificial conditions of excitation current,to achieve the purpose of resources exploration and geological structures identification.Resistivity meter is a prospecting equipment based on DC resistivity method, includingmeasuring and control equipment, interpretation software and other ancillary equipmentsuch as electrodes, cables. In this paper, we design a earth resistivity measurementequipment which use a car battery as power supply, and the receiving system, the maincontrol system, together with the integration of power conversion system are integratedinto one single case.
The system uses a switching power supply to take power from the battery to get thehigh-voltage DC signal, then use the H-bridge circuit to form a low frequency squarewave excitation signal with an interval of positive and negative, which is launched tothe underground through the launching electrode. Transmitter and receiver detect theemission current and receiving voltage signal, which collected by the ADC of the MCUC8051F060, then it transport the measurement results to a PC via RS-232C serialtransmission where and the data storage and processing are completed.
Power system of the instrument use phase-shift control full-bridge ZVS PWM DC-DCconverter, boost circuits and vacuum circuit and linear regulator circuits to satisfy theneeds of400V high-voltage,±15V, and5V and3.3V DC Power Supply. Forphase-shifted full-bridge DC-DC converter, an integrated PWM controller UCC3895isused as the control core, and the boost circuit is implemented with a integrated DC-DCconverter MC34063. The instrument control system consists of two control layers,including a PC as upper computer and a MCU as lower computer. PC is responsible forsetting the measurement parameters and commands, and storage and processing ofmeasurement data, etc.; MCU C8051F060control the system and accomplish dataacquisition according to measurement command set by the upper computer, PC and MCU communicate through the RS-232C serial port.
The system does a lot of work to improve the measurement accuracy, optimizeperformance and enhance stability. In power system, working power is divided intodigital and analog power supply, the digital and analog ground are separate, usingone-point grounded to reduce the interference to the high-precision analog circuitscaused by the digital circuits. In the control system, the MCU and power circuit isisolated by optocouplers, in order to reduce the interference to the high-precision analogcircuits caused by the power circuit. The excitation signal use a low frequency squarewave excitation signal with an interval of positive and negative, to measuring thenatural potential when the excitation current is zero and a group of opposite excitationsignal when the excitation current is not zero, then through the subsequent dataprocessing to eliminate the interference to the measurement result caused by earthnatural potential and the electrode polarization potential. In signal detection system,using the Hall current sensor to complete insulation measurement, in order tocircumvent the influence to the system under test when using the resistance samplingmethod; in receiving voltage detection system, using two programmable gaininstrumentation amplifier as preamplifier to suppress common mode interference andimprove signal to noise ratio, and adjust the measured signal amplification to the bestADC quantization interval, a50Hz notch filter circuit is used to suppress the powerfrequency interference. In addition, the system components use industrial gradeoperating temperature level, and the entire measurement system are integrated in asingle box, in order to improve the stability of the instrument when work in harshconditions.
系统使用开关电源从蓄电池取电，得到高压直流信号，然后经过H桥电路形成正负相间的低频方波激励信号，并通过发射电极向地下发射。发射机和接收机分别检测发射电极中的发射电流和接收电极中的接收电压，由微控制器C8051F060对调理后的信号进行A/D采集，然后将测量结果通过RS-232C串口传输给PC机，由PC机完成数据的存储和处理工作。
仪器的电源系统方面，分别采用移相控制全桥软开关脉宽调制DC-DC变换器、Boost升压电路和负压电路、线性稳压电路等方案，以满足相应的400V高压、±15V及5V和3.3V等直流稳定电源的需求。其中移相全桥直流-直流变换器中，采用集成PWM控制器UCC3895组成控制电路，Boost升压电路采用集成直流-直流变换器MC34063作电路核心。仪器的控制系统应用PC机作上位机和微控制器作下位机的两级控制思想，PC机负责设置测量参数和命令，存储和处理测量数据等工作，微控制器C8051F060根据上位机设定的测量命令，完成对测量主机的控制和数据采集工作，两者通过RS-232C串口进行通信。
系统在提高测量精度，优化工作性能和增强稳定性方面作了许多工作。在电源方面，系统工作电源分为数字电源和模拟电源，同时数字地和模拟地分开，并采用一点接地方式，以降低数字电路对高精度模拟电路的干扰。控制系统中，微控制器通过光耦和被控制部分进行隔离，以降低功率电路对控制电路的影响。在激励信号方面，采用正负相间的低频方波信号，并在激励电流为零时测量自然电位，在激励电流不为零时，测量一组相反的激励电位，然后通过后续的数据处理，消除大地自然电位和电极极化电位差对测量结果的影响。在信号检测方面，采用霍尔电流传感器对发射电流进行隔离检测，以规避采用电阻采样法对被测系统的影响；在接收电压检测时，采用两级程控增益仪用放大器组成前置放大器，以抑制共模干扰，提高信噪比，并把被测信号放大到ADC的最佳量化区间，同时加入50Hz陷波电路，以抑制仪器在野外工作时常见的工频干扰。另外，系统的元器件均选用工业级工作温度，整个测量主机集成在同一个箱体中，以提高仪器在恶劣条件下的工作稳定性。
Electrical prospecting belong to the field of geophysical prospecting, and the DCresistivity method is an important method of electrical prospecting. Based on thedifference of the electrical properties of crustal geological, it research space distributionof the underground DC electric field under the artificial conditions of excitation current,to achieve the purpose of resources exploration and geological structures identification.Resistivity meter is a prospecting equipment based on DC resistivity method, includingmeasuring and control equipment, interpretation software and other ancillary equipmentsuch as electrodes, cables. In this paper, we design a earth resistivity measurementequipment which use a car battery as power supply, and the receiving system, the maincontrol system, together with the integration of power conversion system are integratedinto one single case.
The system uses a switching power supply to take power from the battery to get thehigh-voltage DC signal, then use the H-bridge circuit to form a low frequency squarewave excitation signal with an interval of positive and negative, which is launched tothe underground through the launching electrode. Transmitter and receiver detect theemission current and receiving voltage signal, which collected by the ADC of the MCUC8051F060, then it transport the measurement results to a PC via RS-232C serialtransmission where and the data storage and processing are completed.
Power system of the instrument use phase-shift control full-bridge ZVS PWM DC-DCconverter, boost circuits and vacuum circuit and linear regulator circuits to satisfy theneeds of400V high-voltage,±15V, and5V and3.3V DC Power Supply. Forphase-shifted full-bridge DC-DC converter, an integrated PWM controller UCC3895isused as the control core, and the boost circuit is implemented with a integrated DC-DCconverter MC34063. The instrument control system consists of two control layers,including a PC as upper computer and a MCU as lower computer. PC is responsible forsetting the measurement parameters and commands, and storage and processing ofmeasurement data, etc.; MCU C8051F060control the system and accomplish dataacquisition according to measurement command set by the upper computer, PC and MCU communicate through the RS-232C serial port.
The system does a lot of work to improve the measurement accuracy, optimizeperformance and enhance stability. In power system, working power is divided intodigital and analog power supply, the digital and analog ground are separate, usingone-point grounded to reduce the interference to the high-precision analog circuitscaused by the digital circuits. In the control system, the MCU and power circuit isisolated by optocouplers, in order to reduce the interference to the high-precision analogcircuits caused by the power circuit. The excitation signal use a low frequency squarewave excitation signal with an interval of positive and negative, to measuring thenatural potential when the excitation current is zero and a group of opposite excitationsignal when the excitation current is not zero, then through the subsequent dataprocessing to eliminate the interference to the measurement result caused by earthnatural potential and the electrode polarization potential. In signal detection system,using the Hall current sensor to complete insulation measurement, in order tocircumvent the influence to the system under test when using the resistance samplingmethod; in receiving voltage detection system, using two programmable gaininstrumentation amplifier as preamplifier to suppress common mode interference andimprove signal to noise ratio, and adjust the measured signal amplification to the bestADC quantization interval, a50Hz notch filter circuit is used to suppress the powerfrequency interference. In addition, the system components use industrial gradeoperating temperature level, and the entire measurement system are integrated in asingle box, in order to improve the stability of the instrument when work in harshconditions.
引文
[1]刘天佑.地球物理勘探理论[M].北京：地质出版社
[2]刘国兴.电法勘探原理与方法[M].北京：地质出版社
[3]程志平.电法勘探教程[M].北京：冶金工业出版社
[4]李志武.电法勘探仪器的发展[J].地球物理勘探
[5]李晓斌，张贵宾，贾正元.新型分布式高密度电法仪器发展瞻望[J].地质装备
[6]煤炭科学研究院地质勘探分院. DZ-1型数字直流电法仪[J].煤炭科学技术，1987
[7] PASI Instruments&Software. Earth resistivity meter16GL[OL].www.pasigeophysics.com
[8]凤凰地球物理公司. V8多功能电法仪施工简明手册[OL].www.hengda-century.com
[9]布朗M..开关电源设计指南[M].徐德鸿，译.北京：机械工业出版社，2004
[10]张建荣.直流开关电源的软开关技术[M].北京：科学出版社，2003
[11]郑国青，华伟.新型相移PWM控制器UCC3895的应用[J].电子产品世界，2002
[12]许婷，李宏.移相型PWM控制器UCC3895[J].国外电子元器件，2007
[13]张哲，沈虹，王晓寰.基于UCC3895的移相全桥变换器的设计[J].电源技术应用，2006
[14]方波.大功率高频开关电源控制器研究[D].西安：西安理工大学，2006
[15]李昌林.电动汽车车载充电系统的设计与实现[D].武汉：武汉理工大学，2008
[16]郑湘渝.软开关ZVS DC/DC全桥变换器的设计[D].西安：西安理工大学，2005
[17]关国辉.移相全桥软开关高频高压交流电源的设计[D].大连：大连理工大学，2007
[18]马明.直流开关电源及其智能监控系统的研究[D].西安：西安理工大学，2010
[19]楚斌. IR2110功率驱动集成芯片应用[J].电子工程师，2004
[20]宁殿艳，张仲礼，王继矿，汪凯斌，李超.基于ARM Cortex-M3内核矿井直流电法仪的研制[J].西安科技大学学报
[21]管奕.高密度电阻率法测试系统的研究[J].吉林地质，1995
[22]朱栋华，马斌，黄宽，叶健.基于80C552的高密度电阻率法测量系统设计[J].沈阳建筑工程学院学报，2003
[23]付国良.基于桥路级联技术的大功率高密度电法发射装置的研制[D].长春：吉林大学，2009
[24]吴凯.中功率电性源电磁发射机的硬件研制[D].北京：中国地质大学，2011
[25]张贤涛.不接触电极测量仪发射机的研制[D].长春：吉林大学，2006
[26]吕超.分布式井-地电位测量仪接收机的研究与设计[D].长春：吉林大学，2006
[27]张志伟.大深度三维高密度电阻率法接收装置的研制与实验[D].长春：吉林大学，2010
[28]梁冰.高密度电法仪器测控系统设计[D].长春：吉林大学，2010
[2]刘国兴.电法勘探原理与方法[M].北京：地质出版社
[3]程志平.电法勘探教程[M].北京：冶金工业出版社
[4]李志武.电法勘探仪器的发展[J].地球物理勘探
[5]李晓斌，张贵宾，贾正元.新型分布式高密度电法仪器发展瞻望[J].地质装备
[6]煤炭科学研究院地质勘探分院. DZ-1型数字直流电法仪[J].煤炭科学技术，1987
[7] PASI Instruments&Software. Earth resistivity meter16GL[OL].www.pasigeophysics.com
[8]凤凰地球物理公司. V8多功能电法仪施工简明手册[OL].www.hengda-century.com
[9]布朗M..开关电源设计指南[M].徐德鸿，译.北京：机械工业出版社，2004
[10]张建荣.直流开关电源的软开关技术[M].北京：科学出版社，2003
[11]郑国青，华伟.新型相移PWM控制器UCC3895的应用[J].电子产品世界，2002
[12]许婷，李宏.移相型PWM控制器UCC3895[J].国外电子元器件，2007
[13]张哲，沈虹，王晓寰.基于UCC3895的移相全桥变换器的设计[J].电源技术应用，2006
[14]方波.大功率高频开关电源控制器研究[D].西安：西安理工大学，2006
[15]李昌林.电动汽车车载充电系统的设计与实现[D].武汉：武汉理工大学，2008
[16]郑湘渝.软开关ZVS DC/DC全桥变换器的设计[D].西安：西安理工大学，2005
[17]关国辉.移相全桥软开关高频高压交流电源的设计[D].大连：大连理工大学，2007
[18]马明.直流开关电源及其智能监控系统的研究[D].西安：西安理工大学，2010
[19]楚斌. IR2110功率驱动集成芯片应用[J].电子工程师，2004
[20]宁殿艳，张仲礼，王继矿，汪凯斌，李超.基于ARM Cortex-M3内核矿井直流电法仪的研制[J].西安科技大学学报
[21]管奕.高密度电阻率法测试系统的研究[J].吉林地质，1995
[22]朱栋华，马斌，黄宽，叶健.基于80C552的高密度电阻率法测量系统设计[J].沈阳建筑工程学院学报，2003
[23]付国良.基于桥路级联技术的大功率高密度电法发射装置的研制[D].长春：吉林大学，2009
[24]吴凯.中功率电性源电磁发射机的硬件研制[D].北京：中国地质大学，2011
[25]张贤涛.不接触电极测量仪发射机的研制[D].长春：吉林大学，2006
[26]吕超.分布式井-地电位测量仪接收机的研究与设计[D].长春：吉林大学，2006
[27]张志伟.大深度三维高密度电阻率法接收装置的研制与实验[D].长春：吉林大学，2010
[28]梁冰.高密度电法仪器测控系统设计[D].长春：吉林大学，2010