Electronic device for regulating and controlling the delivery of yarn coming from feed units of textile machines

Electronic device for regulating and controlling the delivery of yarn (18) coming from yarn storage units of textile machines, said electronic device comprising at least one local power supply (38) for supplying electric power and means for varying the r.p.m. of a motor (23) so as to keep it synchronised, according to an adjustable scale factor, with the speed of the textile machine to which said device is connected, wherein said motor (23) is, a D.C. brushless motor and said means for varying the r.p.m. of the motor (23) comprise an electronic circuit, which includes at least one microcontroller (21) that controls the r.p.m. of the motor (23) and the currents (I1, I2, I3) circulating in the phases of said motor (23), characterised in that said D.C. brushless motor has three windings, which can be powered at any time to let the rotor of said motor (23) travel depending on a prefixed position of the rotor, so that, with three combinations of use in one direction of said motor windings, said combinations providing for just two windings to be powered at a time, three further intermediate switching combinations can be utilised, wherein, alternately, one winding is connected to the positive pole of said power supply (38) and the other two windings are simultaneously connected to the negative pole of said power supply (38), or vice versa, to obtain six switchings for each motor pole corresponding to six equidistant angular shifts of said rotor.