In the present paper, the equivalence between the magnetic images method and
the classical variable separation method is set up. These methods are separately
applied to calculate the magnetic scalar potentials and the magnetic vector
potentials in the air-gap of some cylindrical synchronous machines, excited
by surface permanent magnets with radial and/or azimuthal magnetisation, and
without polar pieces. The rotor and the stator are assumed slotless, and the
whole electric machine non saturated. The expressions of the magnetic scalar
potentials of each method are interpreted, and their equivalence is established.
The Mayn purpose of this paper is then the demonstration that the magnetic
images method is applicable for the study of simplified synchronous machines.
The interest of the magnetic images use in comparison with the variable
separation method is shown.