Analytical model for mutual inductance between two rectangular coils in driver pickup mode for eddy current testing

Wu, Dehui; Tianfu, He; Wang, Xiaohong; Lingxin, Su

doi:10.1080/10589759.2017.1299733

Cited by 9 publications

(3 citation statements)

References 22 publications

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“…It is from the induced voltage in the Rx (coil) that the status of the test sample is evaluated. However, the total field in the presence of a sample can be considered as a sum of the original field of the coil in the air plus a reflected field from the metal sample [11,32,33]. In presence of a sample to a Tx-Rx probe, there are self-couplings of both Tx (coil) and Rx (coil) through the sample ℒ1, ℒ2 and a mutual coupling of Tx and Rx (coils) through the sample ℳ (remote coupling).…”

Section: Analysis Of Equivalent Circuit Of Tx-rx Pec Probementioning

confidence: 99%

“…= jωL 2 + r 2 (8) The impedance change due to the mutual coupling of the sample and probe ΔZ bears the information about the sample [32]. Whereas, ZTR, the direct mutual impedance of Tx and Rx (coils), in addition to Rx (coil) self-impedance Z form an offset that masks the required information signal [11].…”

Section: Analysis Of Equivalent Circuit Of Tx-rx Pec Probementioning

confidence: 99%

“…1b. Because the resultant value of these two couplings (M and ℳ) depend on coil gap and liftoff [32], we optimized coil gap and lift-off to minimize the offset (M) due to direct coupling of Tx and Rx (coils) . At the optimal lift-off, for every coil gap, the defect detection sensitivity was maximized.…”

Section: Analysis Of Equivalent Circuit Of Tx-rx Pec Probementioning

confidence: 99%

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Investigation of Signal Conditioning for Tx-Rx PEC Probe at High Lift-Off Using a Modified Maxwell’s Bridge

2020

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Pulsed eddy current testing is widely used because of its richness in spectral components. However, the degrading sensitivity as lift-off increases poses a challenge to its application in thick insulation or buried structures and weld areas. In the transmitter-receiver probe, self-impedance (offset) of receiver coil dominates the output signal, reducing the signal-to-noise ratio, especially at high lift-off. This limits the subsequent amplification of the output signal by the signal conditioning circuit. In practice, bridge-based measurements are used to mitigate this challenge but result in small linear range inputoutput characteristics. Electromagnetic interference and stray capacitance effects also cause measurement errors. This paper investigates a modified Maxwell's inductance bridge based on operational amplifier configuration for high lift-off testing. The receiver coil self-impedance is removed to improve signal-tonoise ratio and to make output signal proportional to impedance change only. Experiments are performed to evaluate the performance of the circuit in crack detection. The results show improved signal-to-noise ratio with maximum linearity deviation of 0.30%, and a higher crack detection sensitivity at 30mm high lift-off, in comparison to the conventional bridge circuit with maximum linearity deviation of 0.53%.

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Section: Analysis Of Equivalent Circuit Of Tx-rx Pec Probementioning

confidence: 99%