基于七电极电导率传感器的自容式采集系统设计-电子与通信工程专业论文.docx

华北电力大学硕士学位论文 华北电力大学硕士学位论文 I I 摘 要 海水的电导率是海洋研究过程中的一个重要参数，快速准确的电导率测量对 海洋研究、海洋资源开发等方面有着重要的意义。目前电导率测量主要有电极式 电导率传感器和电磁式电导率传感器两大类，其中七电极电导率传感器因其响应 速度快、精度高的优点而得到广泛的关注。本文通过查阅大量文献、研究国外相 关专利和设备，结合七电极电导率传感器自身特点和实际需求，设计了一套基于 七电极电导率传感器的自容式采集系统。 本文首先对七电极电导率传感器的基本原理和特点进行了阐述，然后根据传 感器本身物理特性以及高精度测量的要求，设计了满足低温漂、高精度的测量电 路。系统选取了大量的高精密、低温漂的器件，驱动信号和采集电路使用同一个 基准源，通过电路设计的合理性去抑制噪声和温漂对系统测量精度的影响；利用 CPU 控制驱动频率，相对传统方式，驱动的频率更加准确，且便于更改；采用模 数转换器实现对信号的高速采样，对采集到的数据利用数理统计和数字信号处理 等相关算法进行处理，能够有效的滤除噪声，进一步提高系统测量精度；系统中 采用实时时钟、大容量存储等集成电路芯片实现数据和相关信息的保存；在数据 的标定过程中，利用最小二乘法拟合曲线。 该采集系统通过标定和检验，达到了预期的精度要求，其他方面性能表现良 好，满足了自容式采集系统的设计要求。 关键字：七电极电导率传感器；电路设计；电导率测量 II II Abstract Conductivity of the seawater is an important parameter during the marine research process, fast and accurate conductivity measurement has important implications for marine research, marine resources development, etc. Currently there are two main categories conductivity measurement, they are electrode conductivity sensors and electromagnetic conductivity sensors. The conductivity sensor with 7 electrodes get widespread attention because of its fast response and high accuracy. Through access to a large number of documents, studies related foreign patents and equipment, with the characteristics and actual demand of the conductivity sensor with 7 electrodes, a self-contained measurement system is designed based on the conductivity sensor with 7 electrodes in this paper. Firstly, the basic principles and characteristics of the conductivity sensor with 7 electrodes are described in the paper. Then it is designed to meet the low temperature drift, high-precision measurement circuit, based on the physical characteristics of the sensor itself and the high-precision measurement requirements. The system selects a number of high-precision and low drift devices, the drive signal and acquisition circuit using the same reference source, to suppress the effects of noise and drift of the system measurement accuracy through rational design of circuits. Using the C