Method for feeding an operating motor of a rolling shutter and a device for a driven rolling shutter

A method for powering an alternating current induction motor (MOT) used to lower or raise a movable element (LD) for closure, privacy, sun protection or screening in a building, by means of a reduction gear (GER) having a substantially different efficiency depending on whether the movable element drives or is driven by the motor, the movable element (LD) comprising a bottom end whose movements between an extreme bottom position and an extreme top position are caused by rotary movements of the motor (MOT), the electric motor being powered, in some periods, at reduced voltage, wherein the absolute value of slip of the motor, measuring the relative difference of speed relative to the speed at zero torque, remains less than the absolute value of slip of the motor when its rotor rotates at rated speed, at least so long as the movable closure element does not encounter an obstacle, the rated speed being defined as the speed of the rotor of the motor when the latter is powered at rated voltage and when the movable element exerts a maximum load.