Helical windings (or zig-zag windings) are used in a number of applications, however in electrical machines mainly employed in low-power, high-speed PM brushless DC machines due to the cost-effectiveness of the winding type while maintaining reasonable performance. Typically, helical winding are used for low voltage applications due to their spiral form, which makes them most suitable for a small number of turns. In high-speed electrical machines such a low number of turns is applicable. It is apparent that high-speed PM machines suffer from rotor eddy-current losses, which in some cases may lead to PM demagnetization due to overheating. The performance of the machine is compromised by these losses, hence they have to be taken into account during the design procedure. There are many papers analyzing the magnetic field of these machines employing helical windings, however none of them present a simple and precise electromagnetic model of a machine with the helical winding. This paper presents an analytical approach to model the resulting three-dimensional magnetic field of the helical winding, taking into account eddy currents in the conducting media of the rotor. The model is verified with 3D FEM by means of comparing magnetic field and rotor eddy-current losses.