Design And Implementation Of New Eddy Current Displacement Sensor Unrelated With The Material Properties

Eddy current displacement detection is one of the important applications of nondestructive detection technology. With the advantages of non-contact, high sensitivity, and low cost, it is developing rapidly in recent years, and it has been widely applied in industrial applications. But according to the principle of eddy current testing, the materials with different conductivity and permeability have different effects on eddy current effect, and it will lead to different test results. When the different materials are detected, the system needs to re-calibrate, which not only reduced the interchangeability of the device, but also greatly increased the workload. Therefore, developing an equipment which can detect materials with different electromagnetic properties is very important. Based on previous research, a displacement device which can detect nonmagnetic materials with different conductivity is designed in this paper. Compared to the previous design of the program, this detection system has a wider range of application in terms of the conductivity of materials. The main works are summarized as follows:(1) The finite element model of the eddy current sensor is built, and according to finite element analysis, the real and imaginary parts of the impedance of the probe coil are decomposed. By observing the relationship between coil’s impedances and data processing, the entire implementation scheme of the detection system is proposed. The simulation results were analyzed and processed to provide data support for circuit design.(2) After proposing the implementation scheme, the entire system is designed. In terms of hardware circuit, the circuit design, simulation and debugging are carried out based on modular thinking. Using mixed analog-digital design, the microcontroller is the core, which completes the control of the system and the data processing. The microcontroller program is written in C programming language. In order to ensure the stability and anti-interference of the system, the production of PCB circuit is completed.(3) After the completion of the system design, experimental platform is set up. Six non-magnetic materials are measured, and the impedance of the coil under different materials and displacement are obtained. The experimental values and simulation values are compared to reduce errors. Finally, test several data of six materials under different displacements, record test results and analyze the results.Through the test results, it can be seen that this displacement detection system can detect different non-magnetic materials, and its measurement is broadened and its usefulness in engineering is improved.