涡流检测磁化管道时频率对线圈阻抗的影响

管道漏磁—涡流复合内检测是一种将漏磁传感器和涡流传感器集成在同一个探头壳体内,用霍尔传感器检测并量化缺陷,再用涡流传感器判定内外壁缺陷的方法。涡流线圈阻抗变化的影响因素有缺陷本身规格形状、缺陷处材料的磁特性以及线圈的激励频率。通过有限元仿真测量了不同激励频率下,涡流线圈经过管道内外壁的缺陷时,线圈的电感、电阻、阻抗和阻抗角的变化规律。结果表明,当线圈的激励频率在200kHz左右时,对内壁和外壁缺陷,线圈的电阻和阻抗角变化较大,而电感和阻抗的变化不明显。试验结果为进一步设计涡流检测电路奠定了基础。

Influence of Frequency on Coil Impedance during Eddy Current Detection of Magnetized Pipeline

The Magnetic leakage-eddy current composite technique used in pipeline inner inspection is to integrate the magnetic flux leakage sensor and the eddy current sensor into the same probe shell.Detection and quantification of defects were realized by Hall sensor and determination of inside and outside wall defects were whereas realized by eddy current sensors.The influence factors of the impedance change of the eddy current coil include the shape of the defect itself,the magnetic properties of the material in the defect and the frequency of excitation coil.In this paper,the variation rule of inductance,resistance,impedance and impedance angle of coil under different excitation frequency is simulated by finite element method and experimental method when eddy current coils pass through defects located inside and outside the tubes.The results show that when the excitation frequency of the coil is about200 kHz,the value of the resistance and the impedance angle of the coil is significantly different for the inside and outside defects under study,while the change of inductance value and impedance value is not obvious.The research results have laid a foundation for the further design of eddy current testing circuit.