摘要
为解决双向励磁涡流检测传感器的信号解调问题,设计了适用于低频范围的正交解调电路(包括移相器、模拟乘法器以及低通滤波器),并对电路各模块的特性进行了测试.通过在移相器中设置滑动变阻器调节两级运放的输入、输出阻抗,可以实现对10~30 k Hz内正弦信号的90°相移,测试了乘法器在工作频段内的直流偏置特性.将解调电路与双向励磁涡流检测传感器应用于钢块不同深度缺陷的检.结果表明:偏置电压基本不随工作频率而波动,进行差值补偿后,计算与电路输出结果的互相关系数为0.955 1,整体解调电路对信号解调的幅值误差小于13%,相位解调误差小于8%.可以检测出45号钢中深7 mm的槽型缺陷,且随着缺陷深度的增加,幅值和相位均呈增长趋势.
To solve the problem of two-directional eddy current signal demodulation,a quadrature demodulation circuit for low frequency range application was designed. The circuit includes a phase shifter,an analog multiplier and a low-pass filter. Their performances were tested in experiments. The circuit can shift the input signal（ in the frequency range of 10-30 k Hz） phase by 90° by adjusting the slide rheostat to modify the input and output impedance of the two-stage amplifier. The DC bias characteristics of the analog multiplier were also tested. Finally,the quadrature demodulation circuit together with the two-directional eddy current probe was applied for detecting notches with various depths in steel block. Results show that the DC bias voltage slightly fluctuates in its operation frequency range.The mutual correlation coefficient of the calculated and tested signal is about 0. 955 1 after amplitude compensation being applied to the tested signal. The relative error in amplitude and phase demodulation results obtained from the circuit is estimated as 13% and 8%,respectively. A notch with a depth of 7 mm can be detected,and both the demodulated amplitude and phase of the eddy current signal tend to approximation increase when the depth of the notches increases.
出处
《北京工业大学学报》
CAS
CSCD
北大核心
2018年第3期363-368,共6页
Journal of Beijing University of Technology
基金
国家自然科学基金资助项目(11402008
11527801
11132002)
北京市自然科学基金资助项目(3154030)
中国博士后科学基金(2014M560029)
关键词
双向涡流
正交解调
移相器
模拟乘法器
two-directional eddy current
quadrature demodulation
phase shifter
analog multiplier
