Study And Design Of The Ring-core Fluxgate Sensor With High Sensitivity

Magnetic sensors have been an essential function for numerous applications; precise geophysical instruments, detection of ferromagnetic objects such as weapons and vehicles, and so on. How to detect the magnitude and direction of weak magnetic field (10?11 to 10?4 T) plays an important role in this field. With a resolution of 0.1–10 nT and a high temperature stability(30ppm/℃), the fluxgate sensors serve for the precise measurement of the magnetic field.The reference papers about fluxgate sensors are studied. the working principle of single core and double core sensors have been stated, and the signal detection methods currently used in the flux-gate technique have been introduced: second harmonic,pulse amplitude,pulse interval and pulse width. Based on characteristics and requirements of weak magnetic field detection, a ring-core fluxgate sensor is designed and fabricated. A metallic ribbon of composition VITROVAC 6025Z is chosen as the magnetic ring-core and 15.625kHz square waveform is used as the excitation frequency. The second-harmonic fluxgate magnetometer has been tested in open-loop. Experimental results show sensitivity is 1.664×104 V/T.The finite element model of fluxgate is built by applicating the Finite Element Analysis Software ANSYS. And the second harmonic component of induced electromotive force is obtained by applicating the function of spectrum analysis in PSPICE9.0. The paper deduces the sensitivity of fluxgate sensor. The result of simulation provides an important basis for designing the structures of fluxgate sensors.