Simulation And Design Of Eddy Current Sensor

Eddy Current Sensor(ECS) with its kinds of advantage is an nondestructive testing component,which has been applied extensively in engineering and science researches.However, the testing performances are sensitive to the material properties (such as resistivityρand relative permeabilityμr), which hampers eddy current sensor applied more conveniently and extensively. So, it is necessary and important to study on how to design the sensor measure circuit, which eliminates the sensitivity.In this thesis, the 3D Finite Element analysis of ECS is done. The new ECS measure circuit is designed, simulated, optimized and experiment. The research work conducted is outlined as following.1. Study on the 3D Finite Element simulation of ECSBased on the electromagnetic foundational theory, the modeling theory and process of Finite Element Method (FEM), two 3D finite element models of ECS are built by simplifying appropriately the original model, selecting the element type, meshing and defining the boundary conditions. After solving them, the results from the two models are compared, then, the effect that inputting frequency to the properties of ECS is revealed, which helps choose a suitable inputting frequency for the circuit2. Design of the new measure circuit of ECSBased on the theory about eliminating the sensitivity of testing performance to material properties, the new measure circuit is designed. The new one produces the outputting signal by converting the real party and the image party of the coil impedance, which get to the purpose of eliminating the sensitivity.3. Simulation and optimizing of the designed circuitThe functions of each module from the designed circuit are checked by the software named Multisim. Based on the results from the simulation, structures and parameters of some modules are optimized to be better.4. Experiment on the new measure circuitBased on the simulated and optimized circuit schematic sheet, a two-layer PCB of the circuit is made by the software named Protel DXP. After completing the PCB, the practical performances of all modules are tested by a digital oscillograph.