Effects of lateral dimensions of the magnetic thin films on the characteristics of thin-film type orthogonal fluxgate sensors
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Fluxgate compass
Biasing
In this paper a double axis planar micro-Fluxgate magnetic sensor is presented. The ferromagnetic core material, the Vitrovac 6025 X, has been deposited on top of the coils with the DC-magnetron sputtering technique, a new type of procedure with respect the existing solutions in the field of Fluxgate sensor. This procedure allows us to obtain a core with the good magnetic properties of the amorphous ferromagnetic material, typical of a core 25 mum thick, but with a thickness of only 1 mum, typical of a core electrodeposited. The micro-Fluxgate has been realized in a 0.5 mum CMOS process using copper metal lines to realize the excitation coil and aluminum metal lines for the sensing coils. Applying a triangular excitation current of 18 mA peak at 100 kHz the magnetic sensitivity achieved is about 0.45 mV/muT, suitable for detecting the Earth's magnetic field (plusmn50 muT), while the linearity error is 1.15% of the full scale. The maximum angle error of the sensor, evaluating the Earth magnetic field, is 3.4deg. The power consumption of the sensor is about 13.7 mW
Fluxgate compass
Electromagnet
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We have adapted a new printed circuit board (PCB) technology to the fabrication of ultraflat and sensitive fluxgate magnetic field sensors. The two outer layers of the PCB stack compose the electrical windings of fluxgates, while the inner layer is made of a micro-patterned amorphous magnetic ribbon with extremely high relative magnetic permeability (/spl mu//sub r//spl ap/100 000). Two basic configurations were considered: one based on a toroidal magnetic core and the other on a rectangular core with and without an air gap. The field response and sensitivity of the fluxgate devices have been studied as a function of the gap length, the excitation current, and excitation frequency. Compared to fluxgate sensors of similar size, a relatively high sensitivity of 60 V/T was found at 30 kHz for a five-winding detection coil wound around a rectangular E-shaped magnetic core. This high performance is primarily attributable to the high-permeability magnetic core. The results clearly show the potential of this fluxgate device for application as a magnetic sensor.
Fluxgate compass
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Fluxgate sensor is a kind of magnetic sensor which is used in low magnetic field measurement. The key components are magnetic core and exciting current. Easy saturation magnetic core is required and square-wave current excitation is fed to exciting coil in order to make magnetic core operated at saturation region. In this paper, three kinds of ferrite core that had an operating frequency of 2-20 kHz were used in the experiment. Various kind of exciting current was fed to exciting coil and magnetic field detection capability was studied. Resulting of magnetic field measurement in range of 0-600 μT which were obtained from the proposed sensor was show in experiment.
Fluxgate compass
Search coil
Ferrite core
Saturation (graph theory)
Magnetic reactance
Electromagnet
Current sensor
Magnetic circuit
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A novel dual-core 3D CMOS fluxgate magnetic sensor, including device design, manufacturing process, frequency characterizations and measurement of earth magnetic field, is reported in this article. Our design concept that differs from recently developed planar CMOS fluxgate sensors realizes the implementation of conventional wire-winded fluxgate sensors on a silicon wafer and features miniature dimensions and simple post-CMOS process. The fabricated 3D fluxgate is implemented in a 2.5 mm × 2.5 mm chip and comprises two excitation solenoids enclosing the ferromagnetic cores by using wire-bonding technique, which enables a sufficient excitation field to saturate the magnetic cores. Experimental results revealed that the novel device is able to output a linear B-V diagram in the neighborhood of zero-magnetism point regardless of in- or quadrature-phases while operated at 5 V of excitation voltage and 25 kHz of excitation frequency. In addition, the noise analysis indicated the micro-fluxgate has low noise decreasing with the increasing excitation frequency, e.g., 17.03 nT/√Hz at 1 Hz and 1.92 nT/√Hz at 10 kHz. In conclusions, our proposed device not only has enhanced field-to-voltage transfer coefficient (4.7 V/T) and excellent linear B-V characterization, but also is volume-miniature and CMOS-compatible when compared with conventional fluxgate and planar fluxgate sensors.
Fluxgate compass
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We have developed a micro fluxgate magnetic sensor using new printed circuit board (PCB) technology. The fluxgate sensor consisted of five PCB stack layers including one layer of magnetic core and four layers of excitation and pick-up coils. The center layer as a magnetic core was made of micro patterned amorphous magnetic ribbon with an extremely high DC permeability of ~100,000, and the core had a rectangular ring shape. Four outer layers as an excitation and pickup coils had a planar solenoid structure. The amorphous magnetic core was easily saturated due to the high permeability, low coercive field, and closed magnetic path for the excitation field. The chip size of the fabricated sensing element was 7.3 × 5.7 mm2. Excellent linear response over the range of –100 μT to +100 μT was obtained with sensitivity of 780 V/T at excitation sine wave of 3 Vp-p and 360 kHz. A very low power consumption of ~8 mW was measured. This low power, small size, and high sensitive fluxgate sensor to measure a low magnetic field is very useful for various applications.
Fluxgate compass
Electromagnet
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Fluxgate compass
Ribbon
Permalloy
Electromagnet
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Fluxgate compass
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The magnetization state of a magnetic core can be adjusted and controlled by a dc bias coil. A significant voltage may be induced on the bias coil if the coil is coupled with a coil carrying alternative current through the magnetic core. In some practical applications, this induced voltage can cause significant problems. We designed a new type of orthogonally configured core structure to reduce or eliminate the induced voltage. In this design, a C-shape iron-core was orthogonally assembled with a closed iron-core. The closed iron-core was set through the gap of the C-shape core. The C-shape iron-core was wound with the working coil carrying alternative current, while the closed iron-core was with the dc bias coil. Under this configuration, the impedance of working coil could be controlled by applying different dc currents to the bias coil without the risk of inducing voltage on the coil. In our studies, computer simulations as well as laboratory experiments were conducted under different conditions. Test results show that the adjustable impedance range of the working coil is 27%. One of the potential applications for this technique is superconducting controllable reactor for power grids. In this paper, we will present the details of this study.
Coil noise
DC bias
Biasing
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This paper presents a new multistructure fluxgate magnetic sensor composed of Metglas ® Fe-based amorphous HB1 material. The core thickness of the fabricated structure is 0.0254 mm × 30 pieces, and its width is 5 mm. The magnetic loss of the fluxgate core is simulated through finite element analysis. The fluxgate sensor is experimentally analyzed over a frequency range 0.5-3 kHz. The sensor performance exploits the advantages of the multistructure core-shaped magnetic material as well as the second-harmonic operation mechanism. Excellent flux responses are detected for the triangular core sensor, which has different operating frequencies for magnetostriction variation, harmonic response, total harmonic distortion, noise level, sensor vibration, and sensitivity. The influence of magnetostriction, magnetic loss, and permeability in multiangled cores for different frequencies is analyzed. Our multistructure fluxgate sensor is suitable for various applications including power transformer and inverter for interior magnetic core fault detection, owing to its thin-film configuration, high sensitivity, high resolution, and low magnetic loss.
Fluxgate compass
Metglas
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