Research On Multi-channel And Composite-frequency Calibration Technique For Eddy-current Sensors

In this dissertation, some researches on multi-channel and composite-frequency calibration technique for eddy-current sensors were made, which was associating with the national electric power enterprise project named as "Development of eddy-current sensors and their testing software".In chapter 1,the purpose and significance of the dissertation were presented. First, the principle of eddy-current sensors and common calibration methods were introduced. Second, the present research status of dynamic calibration system for vibration measuring sensors at home and abroad was given so as to point out the development trend of dynamic calibration for eddy-current sensors. At last, the main research content and aim of the dissertation were emphasized.In chapter 2, a whole design of multi-channel and composite-frequency calibration system for eddy-current sensors was studied. A multi-channel and composite-frequency calibration system for eddy-current sensors with the comparison method based on a standard acceleration sensor was analyzed in the respects of structure and principle. Especially, its hardware structure was designed.In chapter 3, a multi-channel dynamic calibration technique for eddy-current sensors was studied. Based on the principle and feature of the multi-channel dynamic calibration technique for eddy-current sensors, the fixture and induction disk in the multi-channel dynamic calibration system were analyzed and designed. Particularly, in the respects of interaction of multi-channel inducted eddy currents and dynamic performance of the induction disk, design principle of the induction disk was studied.In chapter 4, a composite-frequency calibration technique for eddy current sensors was studied. First, the principle, optimization method and data acquisition technique of composite-frequency calibration were analyzed, then the amplitude of composite-frequency vibration curve was modulated in order to design a vibration-level-adjustment algorithm. According to the analysis of requirements, multi-channel and composite-frequency calibration software for eddy current sensors was made, and the details of self-checking module, information-input module, parameter-set module and testing module were given.In chapter 5, the developed multi-channel and composite-frequency calibration system for eddy current sensors was experimentally studied. The dynamic test of the induction disk was done and analyzed. Through the experiment of multi-channel dynamic calibration, the influence of multi-sensor calibration and installation of sensors on sensitivity calibration was analyzed. Also researches on composite-frequency calibration for eddy current sensors were done, with comparison of the accuracy of the fixed frequency calibration method. The experimental results indicate that the multi-channel and composite-frequency calibration system can reduce the calibration time and improve efficiency in the condition of guaranteeing the accuracy.In chapter 6, the achievements and future research work were put forwards.