Research on Inductance Calculations for Degaussing Windings of a Double-Layer Steel Cylinder

Abstract

The inductance of degaussing windings is an important parameter for the dynamic current adjustment and overvoltage analysis of ship degaussing systems. This inductance depends on not only the shape, location, and turns of windings, but also on the distribution of the surrounding magnetic medium and its eddy current effect, leading to the difficulty of determining the self- and mutual inductances. To solve this problem, an AC inductance calculation method of degaussing windings considering the eddy current effect was first proposed. The relevant factors affecting calculation accuracy were then analyzed to provide a theoretical basis for the inductance calculation. Aiming at the accurate inductance calculation of a double-layer steel cylinder, a 3D numerical simulation model was established by ANSYS for frequency domain analysis at four different current frequencies (DC, 100 Hz, 1 kHz, and 10 kHz). The relationship between the current frequency and the mesh division in the shell thickness direction was analyzed. Effects of the outer shell on the inductance calculation and its mechanism were also analyzed. The comparative results of the measured and calculated inductance values show that the relative errors are less than 20%. Moreover, the maximum mutual inductance arrives at $21.6~\mu \text{H}$ , indicating a considerable value of the mutual inductance, which cannot be ignored at low-frequency equivalent circuit analysis.

Keywords

• Ship degaussing
• inductance calculation
• eddy current
• current frequency
• accuracy