Analysis of eddy current interaction between a parallel coil and a ferromagnetic pipe with remanence

• A method for analyzing the eddy current interaction between a parallel coil and a ferromagnetic pipe with a remanence is presented.
• A simpler expression for coil coefficient Cs of a parallel coil is deduced in the cylindrical coordinate system.
• We get expression for impedance change of the parallel coil.

Eddy current field excited by a parallel coil placed next to a ferromagnetic pipe with remanence is studied in this paper. The influence of the remanence is analyzed at first. The analytical solutions to the ferromagnetic pipe eddy current field are deduced by means of a second-order vector potential formalism, and the analytical expression for the impedance change of the excitation coil is constructed. Theoretical analysis of the influence for the remanence and the analytical solutions to the eddy current field are verified by experiments.