Electric machine of a magnetic circuit assembled in an unconventional way has got a stator core shaped in a form of a multi-layer helical cylinder made of magnetic sheets. The crosswise stator core steel sheets lamination with respect to the main magnetic axis causes a non-uniform distribution of the core flux along the radial direction. A coiled core presents a complex and non-homogeneous structure that is caused by nonmagnetic gaps between individual coils. Numerical analysis of the field distribution in such a laminated structure is very complex. This is an effect of different magnetic permeability of individual layers of a multi-layer ferromagnetic material. The paper presents the principle of creation of the equivalent core model, its constrains and necessary simplifications. The multi-layer structure is replaced by the equivalent tree-layer structure. The beginning of the model creation process is the machine magnetic circuit calculation based on its equivalent circuit. The magnetic circuit model of the machine is obtained thanks to the introduction of an equivalent stator core that is an equivalent two-layer ferromagnetic divided by a non-magnetic gap of an appropriate length. The model is convenient for the numerical analysis of a field distribution within the two-dimensional, longitudinal and crosswise, machine section.