Einschaltströme in Spulen mit leitendem permeablem Kern bei Berücksichtigung der induzierten Wirbelströme

The influence of eddy currents on the excitation winding impedance of solid and laminated salient pole synchronous machines

“…Nevertheless, in Dreyfus' work, the magnetic flux density does not result from the interaction between the exciting and the induced MMF, since the flux density distribution is a starting point in his analysis. More recently, Nethe [7] and Jäschke et al [8] have been able to determine the reflected impedance [9] of a winding wound on a ferromagnetic core by making use of very advanced analytical models. Both cited works investigate the subject approached by Dreyfus but from a different perspective.…”

“…In the present paper, a combination of the approaches of [6][7][8] is presented. By using some simplifying assumptions, the eddy current density and flux density in the salient pole rotor are first obtained as solutions of a differential problem as in [6].…”

“…By using some simplifying assumptions, the eddy current density and flux density in the salient pole rotor are first obtained as solutions of a differential problem as in [6]. Said solutions are then related to the main geometric dimensions of the electrical machine as in [7,8], in order to evaluate the AC-resistance and inductance of the excitation winding. Resistance and inductance determined by that way show their dependency on frequency enabling the correlation of their cut-off frequencies with the crosssectional shape of the rotor magnetic circuit and the thickness of its eventually laminated steel.…”

Eddy currents induced in a conducting rod of finite length by a coaxial encircling coil

“…Here, we determine the quasi-static field of a cylindrical coil of rectangular cross-section whose centre is at an arbitrary location on the axis of a finite length conductive rod (figure 1). The solution is a generalization of that given by Nethe [6] and uses a similar method, but is not confined to the even source case. The procedure, based on mode matching in a truncated domain, is easily adapted to deal with a finite layered rod or a finite tube.…”

“…Special solutions for the field excited by a coaxial coil encircling a finite rod have been found in this manner for the case where the coil current has even symmetry about the rod mid-plane, perpendicular to the axis. Both time harmonic and transient solutions have been determined [6].…”