Theory and Modeling of Eddy Current Type Inductive Conductivity Sensors

Harms, Julius; Kern, Thorsten A.

doi:10.3390/i3s2021dresden-10103

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…It will be used for testing on sheet metal or other flat surfaces (different types of coil can be made for other applications). The coil, winding and dimensions are calculated using empirical formulas [4,5].…”

Section: A Inspection Coilmentioning

confidence: 99%

Development of an Electronic Instrument for Eddy Current Testing

Mesquita

Palma²,

Oliveira

2022

IJECER

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This article presents the development of a portable electronic variable frequency instrument for eddy current testing. Variations in the conductivity, permeability, or physical characteristics of non-ferromagnetic and ferromagnetic materials cause the impedance of the probe (or coil) connected to a Wheatstone bridge circuit to change. Impedance change causes bridge unbalance, which is indicated by analog and digital indicators on the front panel. The main applications of the equipment are: detection of cracks and surface faults in conductive materials, evaluation of the depths of detected discontinuities, classification of these materials through the variation of conductivity, and evaluation of the thickness of non-conductive layers on a conductive basis. Eddy current testing instruments are superior to equipment that does not use electromagnetic principles for the applications described above. The reason is due to the accuracy and ease of carrying out the inspection. The device developed in this work also has the advantage of the circuits simplicity, the low cost of the electronic components, and the ease of finding them in the market for eventual maintenance. Some test results performed are presented. The instrument performed well for the intended applications.

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Section: A Inspection Coilmentioning

confidence: 99%

Development of an Electronic Instrument for Eddy Current Testing

Mesquita

Palma²,

Oliveira

2022

IJECER

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“…Common non-contact sensors include optical (including laser and fiber optic) interferometric [ 1 ], capacitive [ 2 , 3 , 4 , 5 ], and eddy current [ 6 , 7 , 8 ] sensors. Optical interferometric displacement sensors are irreplaceable in specific applications due to their advantages, such as immunity to electromagnetic interference, large measurement distance and range, and lack of requirements on the target material.…”

Section: Introductionmentioning

confidence: 99%

Single-Ended Eddy Current Micro-Displacement Sensor with High Precision Based on Temperature Compensation

Xu,

Feng,

Liu

et al. 2024

Micromachines

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To measure the micro-displacement reliably with high precision, a single-ended eddy current sensor based on temperature compensation was studied in detail. At first, the principle of the eddy current sensor was introduced, and the manufacturing method of the probe was given. The overall design plan for the processing circuit was induced by analyzing the characteristics of the probe output signal. The variation in the probe output signal was converted to pulses with different widths, and then it was introduced to the digital phase discriminator along with a reference signal. The output from the digital phase discriminator was processed by a low-pass filter to obtain the DC component. At last, the signal was amplified and compensated to reduce the influence of temperature. The selection criteria of the frequency of the exciting signal and the design of the signal conditioning circuit were described in detail, as well as the design of the temperature-compensating circuit based on the digital potentiometer with an embedded temperature sensor. Finally, an experimental setup was constructed to test the sensor, and the results were given. The results show that nonlinearity exists in the single-ended eddy current sensor with a large range. When the range is 500 μm, the resolution can reach 46 nm, and the repeatability error is ±0.70% FR. Within the temperature range from +2 °C to +58 °C, the voltage fluctuation in the sensor is reduced to 44 mV after temperature compensation compared to the value of 586 mV before compensation. The proposed plan is verified to be feasible, and the measuring range, precision, and target material should be considered in real-world applications.

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Design and Potential Analysis of an Eddy Current Sensor for Inductive Conductivity Measurement in Fluids

Harms

Kern

2021

The 8th International Symposium on Sensor Science

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In the scope of this paper, a first exemplary eddy current sensor for seawater conductivity measurement is developed, based on the derived sensor theory of a previous work. By high-frequency excitation, eddy currents are induced in the fluid and are counter-fields measured with a sensing coil. The coil’s resonance point is used for amplification. The developed prototype is analyzed based on a derived transfer function and FEM simulations. The theory is validated using a prototype implementation. With conducted experiments on a sensor test bench, the characteristics are confirmed and disturbances identified. It is shown that frequencies exist where temperature influence is minimal. This work gives a perspective for a novel sensor to allow seawater conductivity measurement.

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Theory and Modeling of Eddy Current Type Inductive Conductivity Sensors

Cited by 3 publications

References 6 publications

Development of an Electronic Instrument for Eddy Current Testing

Development of an Electronic Instrument for Eddy Current Testing

Single-Ended Eddy Current Micro-Displacement Sensor with High Precision Based on Temperature Compensation

Design and Potential Analysis of an Eddy Current Sensor for Inductive Conductivity Measurement in Fluids

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