Low-frequency eddy current testing using HTS coil driven by PWM inverter

Teruyoshi Sasayama, Keiji Enpuku

Research output: Contribution to journalArticle

Abstract

When testing ferromagnetic materials such as iron, low-frequency eddy-current testing (LF-ECT) is used to avoid the skin effect. However, the drawback of LF-ECT is that the signal becomes weak at low frequencies. Furthermore, when the specimen is covered with protective materials, the signal becomes even weak, owing to the large lift-off. To overcome these drawbacks, we utilize a high-temperature superconducting (HTS) coil and a pulse-width modulation (PWM) inverter in the LF-ECT method. Using an HTS coil and a PWM inverter, strong currents are conducted, and the change in the coil resistance can be easily measured. The small impedance change of the HTS coil is detected by using a Maxwell bridge. The result demonstrates that a steel plate thickness of up to 20 mm can be estimated based upon the measurements of the change in the coil resistance, even when the lift-off is 98 mm.

Original languageEnglish
Pages (from-to)1275-1282
Number of pages8
JournalInternational Journal of Applied Electromagnetics and Mechanics
Volume59
Issue number4
DOIs
Publication statusPublished - Jan 1 2019

Fingerprint

Eddy current testing
pulse duration modulation
eddy currents
Pulse width modulation
coils
low frequencies
Skin effect
Ferromagnetic materials
Steel
Temperature
Iron
ferromagnetic materials
Testing
Superconducting coils
steels
impedance
iron

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

Cite this

Low-frequency eddy current testing using HTS coil driven by PWM inverter. / Sasayama, Teruyoshi; Enpuku, Keiji.

In: International Journal of Applied Electromagnetics and Mechanics, Vol. 59, No. 4, 01.01.2019, p. 1275-1282.

Research output: Contribution to journalArticle

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