Physically, the system has a rotor magnet into four stator iron core coils. A pair of coils is excited when the other pair is open. The timing of the electric excitation of each pair of coils allows the rotor turn in steps of 90º. The coils are excited such a way that the rotor magnet turn 90º by the atraction of the non excited coils iron core, not by the field of the excited coils like on normal motors. A figure of the simulated system is presented:NOWARM