基于FPGA的磁感应式电导率测量系统研究

he technique of magnetic induction conductivity measuring is a kind of measurement based on the principle of magnetic induction and aims at the electrical characteristics of object.This thesis studies and designs a kind of magnetic induction conductivity measuring system integrated excitation and phase detection on the basis of the principle of magnetic induction. We adopt DDS based on FPGA to design the excitation,and it elevates the capability and controllability of system, meanwhile, it reduces the volume of system and lays necessary foundations for the system integration. The technique of zero-crossing detection is adopted for the phase detection. And get the phase difference of the eddy current field and the exciting magnetic field.It simplifies the structure of system further. It has high steady and its maximum phase drift is 0.03 . We experiment on laying NaCl solution with different dimension and different conductivity at different positions in the surveyed area.The experiments turn out that this system is sensitive at the center of the surveyed area,and the value of the phase detection is different for different dimension and different conductivity which are in conformity with the principle of electromagnetic field. It can be used for conductivity measuring.