A rotating electrical machine of the double stator configuration includes a rotor shaped as a hollow cylinder disposed concentrically between an outer stator and an inner stator. The rotor can include plurality of radially spaced magnet cavities configured to receive permanent magnetic bars. To provide sufficient stiffness and rigidity, the rotor may be made from fiber composite material. To simplify construction, the rotor can be assembled from a plurality of rotor segments radially arranged about an axis line in which the magnet cavities are disposed.