Xiang Yike, Tytko Grzegorz, Luo Yao, Makowska Jolanta
State Key Laboratory of Power Grid Environmental Protection, School of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, China.
School of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, China.
Materials (Basel). 2025 May 20;18(10):2376. doi: 10.3390/ma18102376.
This work presents a system developed to determine changes in the impedance of an eddy current probe placed above a conductive disc containing two layers of different diameters. In the first step, an analytical model was derived with an employment of the truncated region eigenfunction expansion (TREE) method. The final formula for the probe impedance change was presented in a closed form, which makes it possible to implement it in any programming language or computer algebra system. The mathematical model was implemented in MATLAB and used to design probes and to determine the optimal test parameters. In the next step, two eddy current probes with a single coil with different geometric dimensions were constructed. Impedance measurements were carried out using an LCR meter for three sets of double-layer discs. The tested discs were made of materials with different electrical conductivities. The upper and lower layers of the disc also differed in terms of the geometric dimensions, i.e., the diameter and thickness. The tests were performed for the operating frequency of the probe ranging from 1 kHz to 10 kHz. In all cases, a very good agreement was obtained between the measurement and the calculation results. Both the error in the changes in resistance and the error in the changes in reactance did not exceed 3.5%.
这项工作展示了一个开发的系统，用于确定放置在包含两层不同直径的导电圆盘上方的涡流探头的阻抗变化。第一步，采用截断区域本征函数展开（TREE）方法推导了一个分析模型。探头阻抗变化的最终公式以封闭形式给出，这使得它可以在任何编程语言或计算机代数系统中实现。该数学模型在MATLAB中实现，并用于设计探头和确定最佳测试参数。下一步，构建了两个具有不同几何尺寸的单线圈涡流探头。使用LCR仪表对三组双层圆盘进行了阻抗测量。测试圆盘由具有不同电导率的材料制成。圆盘的上层和下层在几何尺寸方面也有所不同，即直径和厚度。在探头1 kHz至10 kHz的工作频率范围内进行了测试。在所有情况下，测量结果与计算结果都取得了非常好的一致性。电阻变化的误差和电抗变化的误差均未超过3.5%。
