Patent ID: 6861819

Claim:
An electronic device for starting a permanent-magnet synchronous motor including a stator having a central axis and a permanent-magnet rotor having a reference axis separating the north from the south pole, and comprising: logic control means; at least one switch arranged in series between an external power supply source and a permanent-magnet synchronous motor; and sensor means suitable to determine the polarity and position of the rotor of said motor, wherein said logic control means are suitable to provide a driving signal for said switch means as a function of a signal that arrives from said sensor means and a voltage signal of said external power supply source, and wherein said sensor means are arranged at an angular position Φ SH , the angle Φ SH being determined so as to simultaneously satisfy the equations Φ 0 <Φ SH <(180+Φ 0 ) and (Φ R −θ L )<Φ SH <(180+Φ R −θ L ) where Φ 0 is the angle of the rotor reference axis to the central axis when the rotor is at rest, Φ R is the angle of the rotor reference axis to the central axis during operation of said rotor at the zero crossing point of the voltage of said external power supply source, and θ L is the phase shift between the voltage of said external power supply source and the current that circulates in the coils of the stator of said motor.