The Development Of Multi-variable Magnetic Sensor And Its Simple Applications

In this paper we discussed the behavior of a coil with a magnetic core under a magnetic field and connected with an ac signal, By the property of magnetic field induced change of permeability, which may be called magnetopermeability (MP) imitating the definition of dc giant magnetoresistance (GMR). The field induced change of inductance and the field induced change of the equivalent capacitance, ac resistance and impedance caused by that in the coil have been observed. Based on this, multiparameter magnetic-field sensitive sensor has been developed. Based on the behavior of magnetoimpedance caused by the multiparameter magnetic-field sensitive, a new equipment of dc current monitoring with the coil has been designed.By means of adding a loss film, which is placed at one end and vertical to the centre axis of the coil, all of those field induced changes of the parameters can approach or exceed 40% under a field less than 1600 Oe and with a signal frequency of 10 kHz. A spiral coil with a magnetic core shows the manifold and highly sensitive effects of magnetic field susceptivity participated by an ac signal with a higher frequency. When the signal frequency is at 100 kHz, The ML can reach about 58% and the estimated value of GMI can reach about 89% under a field of H= 300 mT, On the other hand, the magnetic field to reach the saturation value is about 50 mT. Thus the area 0 _ H _ 50 mT can be named as sensitive area. In addition, the effect above can exist in the whole range of temperature below the Curie point of the ferrite Tc = 755 KCompared to similar effect obtained from many intrinsic characteristics of materials,. the effect caused by that in the coil is not only strong, but output stability. The effect here is not simply stems from the intrinsic characteristics of materials, but materials will be passed into the sensor portfolio acquired. Sensors made of such a coil have Highly sensitive, simple structure, low-cost and can be expected to be applied in many fields. The sensor show giant magnetoimpedance (GMI) with a higher frequency, and this effect can be used conveniently to fabricate dc current monitoring equipments. The present equipment has an enough sensitivity to be an ammeter or a current controlling unit. In addition, if using a suitable relay to replace the voltmeter in the present equipment, a new device of overflow protection with higher sensitivity and efficiency can be fabricated.Compared with earlier studies, the selectivity of the material is not strong. Most of the use of magnetic materials can be observed that the giant magnetoimpedance and magnetocapacitance effects. The giant magnetoimpedance and magnetocapacitance effects can be observed in a wide frequency range, and not dependent on the skin effect. resonance phenomenon of magnetopermeability appearance in a high frequency, so magnetoimpedance and magnetocapacitance have a drastic changes. Positive and negative magnetoimpedance can be observed in a certain frequency range.