Research On An Automatic Static Calibration Device Of Eddy Current Sensors

This dissertation did some research on an automatic static calibration device of eddy current sensors theoretically and experimentally due to the need of calibrating eddy current sensors in the electric power industry.In chapter 1, the significance and the background of this research were presented. First, the features, the application and the calibration principle of eddy current sensors were introduced. Secondly, the research status about the static calibration device of eddy current sensors at home and abroad was analyzed. Finally, the purpose and the content of this dissertation were presented.In chapter 2, the overall design for an automatic static calibration device of eddy current sensors was researched. The specifications of this device was proposed, and then the overall structure was analyzed, and the design principle of this device was studied preliminarily.In chapter 3, the mechanical structure for the automatic static calibration device of eddy current sensors was studied. According to the functional requirements, the motion mechanism was first analyzed, and then the design method of the guide part, the motion part and the base in the device was studied. Secondly, the installing fixture of sensors to be calibrated was analyzed, and the design method of the multifunctional fixture, the adjusting mechanism of a zero point, and the locking mechanism were studied. Finally, the operation security of the device was analyzed.In chapter 4, the measurement and control system based on FPGA for the automatic static calibration device of eddy current sensors was studied. First, the design method of a closed-loop control module for the accurate motion positioning of a mechanical structure was studied. Secondly, the design method of a displacement measurement module for measuring displacement and controlling motor was studied. Thirdly, the design method of a voltage measurement module for converting the analog output from an eddy sensor into the digital signal was studied. Finally, the communication module for the data transmission between the measurement and control system and the PC was studied.In chapter 5, the software of a superior computer based on LabVIEW for the automatic static calibration device of eddy current sensors was studied. First, the whole structure of software was analyzed. Then, according to the different functions, the design method of the data transmition module, the data acceptance module and human-computer interface were studied respectively.In chapter 6, several experiments were conducted on the device. First, the driving and control module of the stepping motor for control precision was tested. Secondly, the displacement measuring module for measuring precision was tested. Thirdly, the measuring precision of the voltage measurement module, the stability of the constant voltage power supply and the stability of the constant current power supply were tested. Finally, the whole device was tested to verify the agreement with the technical specifications and the design requirement.In chapter 7, the achievements of the thesis were summarized briefly and the the further research work need to be done was expected.