多功能接地电阻测试仪的设计

多功能接地电阻测试仪的设计(论文15000字)
摘要：接地电阻是接地系统中一项重要的技术指标，通常用接地电阻来衡量接地设施的有效性能，不同类型的接地系统对接地电阻有着不同的要求。科学准确地测量接地电阻是在实际工程实践中一项重要的任务。本文首先介绍了接地电阻的测量方法和意义，对目前市场上接地电阻测试仪产品进行了调研。在此基础上，以STM32F103C8T6作为主控，根据四线法测量接地电阻和土壤电阻率的原理，设计了一种多功能接地电阻测试仪。由DDS芯片AD9850设计正弦激励信号，利用LM324构建交流恒流源，程控放大器AD603设计信号调理电路，并利用AD637和主控内置ADC采集电压幅度信号。通过互感、整流滤波电阻分压的方法测量地电压。系统以LCD12864显示测量结果，通过独立按键进行测量模式选择与操作。测量结果可存储在本地，并可通过串口将测量结果发送至电脑。最后对系统进行了调试和测试，结果表明测量接地电阻精度较高，功能较丰富，为接地电阻测试仪的设计提供了一种新思路。
关键词：接地电阻；四线法；土壤电阻率；测量

Design of Multi - function Grounding Resistance Tester
Abstract:Grounding resistance is an important technical index in the grounding system. It is usually used to measure the effective performance of grounding facilities with grounding resistance. Different types of grounding systems have different requirements for grounding resistance. Scientific and accurate measurement of grounding resistance is an important task in practical engineering practice. In this paper, the measurement method and significance of grounding resistance are introduced, and the products of grounding resistance tester are researched. On this basis, STM32F103C8T6 as the main control, according to the four-wire method to measure the grounding resistance and soil resistivity principle, designed a multi-function grounding resistance tester. Designed by DDS chip AD9850 sinusoidal excitation signal, using LM324 to build AC constant current source, programmable amplifier AD603 design signal conditioning circuit, and use AD637 and master control built-in ADC to collect voltage amplitude signal. Through the mutual inductance, rectifier filter resistor divider method to measure the ground voltage. The system displays the measurement results with the LCD12864, and selects and operates the measurement mode with the independent keys. The measurement results can be stored locally and can be sent to the computer via the serial port. Finally, the system is debugged and tested. The results show that the measurement grounding resistance is high and the function is rich, which provides a new idea for the design of grounding resistance tester.
Keywords: grounding resistance; 4 rod-bed; soil resistivity; measure
 

目 录
1 绪论    1
1.1课题的研究对象及其意义    1
1.2接地电阻测量方法以及测量装置的发展    1
1.2.1接地电阻测量方法的发展    1
1.2.2接地电阻测量装置的发展    2
1.3 本文工作内容    3
2 设计方案论证    4
2.1 本设计的目的    4
2.2本设计的技术方案    5
2.2.1 单片机主控芯片的选择    5
2.2.3接地电阻与土壤电阻率测量回路的设计    6
2.2.4 地电压测量回路的设计    6
2.2.5 存储系统的设计    6
2.2.6 电源模块的设计    7
2.2.7LCD显示模块与按键的设计    7
3 系统硬件设计与实现    7
3.1主控模块电路    7
3.2正弦恒流源激励的设计    8
3.2.1正弦信号源电路的设计    8
3.2.2 正弦信号功率运放电路的设计    10
3.3接地电阻与土壤电阻率测量回路的设计    12
3.3.1程控增益电路的设计    12
3.3.2AD637真有效值检测电路的设计    13
3.4地电压测量回路的设计    14
3.5存储系统的设计    15
3.6 电源模块的设计    15
3.6.1 +5V电源的设计    16
3.6.2-5V电源的设计    16
3.6.3 3.3V电源的设计    17
3.7LCD显示模块与按键的模块设计    17
4系统软件设计    18
4.1接地电阻测试仪的主程序设计    18
4.2子程序设计    19
4.2.1AD9850子程序    19
4.2.2DAC7512N子程序    21
4.2.3LCD12864子程序    23
5系统调试    25
5.1软件调试    25
5.2硬件焊接、调试    25
5.2.1 电源调试    25
5.2.2 正弦信号产生电路与恒流源电路    25
5.2.3 真有效值检测电路    26
5.2.4 DA转换与测量电路    26
5.2.5 系统调试    26
6总结    26
参考文献    27
致谢    28