高灵敏度感应式磁传感器的研究

Research of high sensitivity inductive magnetic sensor

大地电磁测深需要较宽频率范围的感应式磁传感器来探测大深度范围,然而,随着频率的降低磁传感器的感应电压也随之降低;高频段由于磁性材料在磁化时存在趋肤效应,导致磁芯的有效面积变小,因此,提高磁芯的有效导磁率以及磁芯材料的有效面积是扩展频带提高传感器灵敏度的主要手段。采用高电阻率叠片磁芯并且在磁芯两侧附加磁通收集器的办法增加有效面积和有效导磁率从而提高传感器的灵敏度。标定结果表明传感器频率范围是0.001 Hz～10 kHz,在频率小于1 Hz的范围内灵敏度为0.24 V/(nT·Hz),频率高于1 Hz时,为0.75 V/nT,能够满足大深度范围探测的需要。

Magnetotelluric （MT） sounding requires a wide frequency-range magnetic sensor to enable large depth range detection. However, the inductive voltage decreases as frequency decreases, and the effective area of the mag- netic core reduces because of skin effect when magnetic material is magnetized at high frequency. So, improving the apparent permeability and effective area of the magnetic core is the main method to increase the sensitivity and expand the frequency band of the sensor. In this study a magnetic core made of high resistance laminated magnetic metal sheets is used and magnetic flux concentrators are added on both sides of the magnetic core, which increases the effec- tive area and apparent permeability of the magnetic core, and eventually increases the sensitivity of the sensor. Calibra- tion results indicate that the frequency range of the sensor is 0. 001 Hz - 10 kHz and its sensitivity is 0.24 V/ （ nT · Hz） below 1 Hz, and 0.75 V/nT above 1 Hz, which could meet the requirements of large depth range detection.