Design of PCB search coils for AC magnetic flux density measurement (original) (raw)
Related papers
Calibration Technique for Rotating PCB Coil Magnetic Field Sensors
Sensors and Actuators A: Physical, 2019
A high-accuracy calibration of inductive coil sensors based on Printed Circuit Board (PCB), commonly used in rotating coil field measurements of particle accelerator magnets, is presented. The amplitude and phase of signals with and without main field suppression are compared in order to simultaneously determine both the PCB rotation radius and the transverse offset of its plane from rotation center. The accuracy of planar wire placement on the PCB boards is exploited to create loops highly precise in area which rotate at different radii. Such an area reproducibility and circuit geometry allow the suppression of the fundamental field, enabling the calibration, as well as improving signal resolution and mitigating vibration effects. Furthermore, the calibration can be performed dynamically, insitu during measurements. Calibration accuracy is validated experimentally by referencing the PCB positions with a Coordinate Measuring Machine (CMM).
Sensors & Transducers, 2012
A theoretical and experimental comparison of optimized search coils based magnetometers, operating either in the Flux mode or in the classical Lenz-Faraday mode, is presented. The improvements provided by the Flux mode in terms of bandwidth and measuring range of the sensor are detailed. Theory, SPICE model and measurements are in good agreement. The spatial resolution of the sensor is studied which is an important parameter for applications in non destructive evaluation. A general expression of the magnetic sensitivity of search coils sensors is derived. Solutions are proposed to design magnetometers with reduced weight and volume without degrading the magnetic sensitivity. An original differential search coil based magnetometer, made of coupled coils, operating in flux mode and connected to a differential transimpedance amplifier is proposed. It is shown that this structure is better in terms of volume occupancy than magnetometers using two separated coils without any degradation ...
Performance analysis of miniaturized PCB coils for small-aperture magnet qualification
2015 IEEE SENSORS, 2015
The metrological performance of a magnetic field transducer, consisting of a fyberglass cylinder hosting three PCB coils with a diameter of 7.5 mm, is analyzed. The transducer aims at facing the more challenging goals expected in the near future of particle accelerators, involving magnet apertures smaller than 1 cm. Main intents are to gain useful feedback to designers for optimizing the manufacturing and improving the metrological performance of the transducer.
Rotating-Coil Measurement System for Small-Bore-Diameter Magnet Characterization
Sensors
Rotating-coil measurement systems are widely used to measure the multipolar fields of particle accelerator magnets. This paper presents a rotating-coil measurement system that aims at providing a complete data set for the characterization of quadrupole magnets with small bore diameters (26 mm). The PCB magnetometer design represents a challenging goal for this type of transducer. It is characterized by an aspect ratio 30% higher than the state of the art, imposed by the reduced dimension of the external radius of the rotating shaft and the necessity of covering the entire magnet effective length (500 mm or higher). The system design required a novel design for the mechanical asset, also considering the innovation represented by the commercial carbon fiber tube, housing the PCB magnetometer. Moreover, the measurement system is based primarily on standard and commercially available components, with simplified control and post-processing software applications. The system and its compon...
Sensors and Actuators A: Physical, 2008
The twisting of a pair of leads connecting to a search coil used for detection of magnetic field or flux density reduces errors due to stray magnetic fields. Although this method is commonly used, the influence of stray fields is often underestimated. This could lead to degradation of the accuracy of measurements. This paper presents an analysis of the influence of the quality of wire twisting and its possible influence on the signal-to-noise ratio. Twisted wires are approximated as a two-dimensional configuration, for which typical results of calculations are presented. The paper also reports the results from measurements using manually and machine-twisted pairs of wires. The analysis shows that the stray field influence can be reduced by up to 60% by proper twisting of a pair of wires connecting a sensor to measuring equipment.
Investigation of Noise Reduction and SNR Enhancement in Search Coil Magnetometers at Low Frequencies
Here, a generalized induction coil sensor model, more generalized than other models, has been considered and the equivalent magnetic field of the coil thermal noise and the sensor signal to noise ratio are calculated theoretically based on the dimensions and geometry of the coil winding and its core. Our calculations indicate that the equivalent magnetic field of the thermal noise can be minimized by the coil to core weight ratio. Moreover, it is found that the sensor signal to noise ratio can be maximized with only a special value of core aspect ratio length to diameter of core ratio. The calculation results here exhibit good agreement with the experimentally measured noise data.
Design and Construction of Eddy Current Sensors with Rectangular Planar Coils
Eddy current sensors with rectangular planar coils were designed, constructed and characterized. The rectangular planar coils have a maximum testing area of 2.25 cm2 and an output impedance in the range of the entrance impedance of normal commercial equipment (5 to 200 Ohm). Two out of eight different windings have been studied so far, their electrical properties have been measured and calculated. In the characterization, sensor performance for three different eddy current applications has been checked, namely detection of surface and edge cracks and material sorting through resistivity assessment. The results were compared to those from a standard cylindrical probe. A frequency range between (0.3-2.0) MHz was selected for crack inspection . Special testing pieces were prepared from Zircaloy-4 blocks. Crack signal analysis showed good amplitude discrimination and rather poor phase discrimination. To test the resistivity response, a resistivity standard box and a Zircaloy-4 sample we...
Optimized Mini Search Coil Magnetometer Suited To Large Bandwidth Applications
2011
In the framework of a collaborative work with industry aiming at the development of a robust smal l size (1 cm) large bandwidth magnetometer, a theoretical and experimental comparison of optimized search coils b ased magnetometers, operating either in the Flux mode or in the classical Lenz-Faraday mode, is presented. The impr ovements provided by the Flux mode in terms of bandwidth and measuring range of the sensor are detailed. A compact original flux mode differential magnetometer is presented and detailed in terms of measurement rang e, bandwidth and transfer. Theory, SPICE model and measurements are in perfect agreement. Keywords-search coil sensor; differential magnetometer; transimpedance amplifier; biomedical and geomagnetic measurements; non destructive evaluation
Geometrical analysis of planar coil design for fluxgate magnetometer
Microsystem Technologies, 2010
This paper presents geometrical analysis on the design of planar coupled coils for use as magnetic sensors. Inductance and magnetic coupling of the coil are analyzed using field solver analyzer ASITIC. Effects of different coil parameters, such as winding number, spacing, and width are discussed in detail. As results, the coil design considers not only the inductance value and the height of magnetic coupling, but also the geometrical area consumed. The analysis is verified by experimental data from coupled coil fabricated using surface micromachining techniques. An outer coil area having a typical dimension of 1.8 9 1.8 mm 2 and a fix inner coil diameter of 500 lm was fabricated. Coupling factor of about 0.7 and self inductance of 12.7 nH were achieved, which show a reasonably good agreement with the simulated results. The coil platform developed offers an integrated solution for the design of fluxgate magnetometer.
Multilayer planar rectangular coils for eddy current testing: Design considerations
NDT & E International, 2009
Planar rectangular coils provide some interesting features different from those of pancake coils, such as good performance in conductivity measurement at high frequencies, high sensitivity to scratches and other shallow imperfections and the possibility of inspecting complex surfaces. The impedance of these coils has been modeled by different authors. A brief discussion of some analytical approaches in the literature is presented and calculations using the second-order vector potential approximation are introduced, aimed at the study of the influence of coil shape and size on the sensitivity to electrical conductivity of the substrate. Three cases were modeled, (A) coil in free space-inductance L 0 as a function of number of turns (n) and width of the spiral conductive lanes (c) for different coil inner shape factor (rr i ); (B) coil on a conductive substrate (Zircaloy-4)-impedance change, DZ, as a function of f?s, the product of the test frequency (f) and the substrate electrical conductivity (s) for different rr i and (C) coil sensitivity to small changes in s(Ds).