Curvature-related eddy-current losses in laminated axial flux machine cores

In this paper we present an axiperiodic quasi-static model to evaluatethe magnetic flux density distribution and power loss due to curvature related radialflux in the laminated core of axial flux machines. It is shown that the relatively loweffective permeability in the radial direction and the shielding effect of induced eddycurrents result in negligible radial flux density compared to the peak flux densities inthe axial and circumferential directions. This justifies the assumption of zero radialflux which simplifies electromagnetic modelling of axial flux machine cores. Themodel predicts that power loss due to curvature related radial flux is insignificantcompared to normal eddy current loss if the core permeability, core conductivity andnumber of poles are sufficiently high. A laboratory technique is proposed for thepractical detection of power loss due to curvature related radial flux