The generator device of electrical energy with permanent magnets, particularly for the supply of electrical loads and/or batteries of vehicles, connectable to at least a driving shaft of a motor, comprises: a rotor element rotating around an axis of rotation; a stator element contained inside the rotor element, or containing the rotor element, and coaxial to the rotor element, the stator element having a plurality of stator slots; a plurality of stator windings of a conductive material arranged at each of the stator slots and connected to a power supply line; a plurality of permanent magnets having a first side associated with the rotor element and a second side facing the stator element; wherein the permanent magnets are associated with the rotor element in a configuration of the Halbach array type to define a magnetic coupling to the stator windings wherein the magnetic field flow at the second side of each of the permanent magnets is substantially greater than the flow of the magnetic field at the first side of each of the permanent magnets.