Effects of permeability of magnetic materials on errors of the T-Ω method

The error inherent in the T-Ω method due to cancellation between the current vector potential T and gradΩ terms is investigated by solving typical models. The cancellation error is examined using not only an axisymmetric simple model but also a three-dimensional one. The effect of permeability on the error of the T-Ω method is quantitatively examined using the simple model under DC and AC excitations. The errors in single precision and double precision are also investigated, and the allowable range of permeability is discussed. The magnetic field of the IEEJ model analyzed, and the calculated results are compared with measured ones. It is concluded that, although in general the error increases with the increase in permeability, the magnitude of the error is negligibly small if the calculation is carried out in double precision