Patent ID: 8222856
Filing Date: 2012-07-17
Classification: H02P

Abstract:
1. A control system (CS), without position sensors, for a synchronous, rotary electric motor (M), comprising: an electronic switch (TR) operatively connected in series with a stator winding (W) of the motor (M) between a first terminal and a second terminal (A, B) which are intended to be connected to a supply of an alternating voltage (V), first detector means suitable for providing an electrical signal (Vzc) indicative of the sign and of the zero-crossings of the alternating supply voltage (V), second detector means suitable for providing signals indicative of the sign and of the zero-crossings of the back-electromotive force which is developed in the stator winding (W) in operation, and control means (MC) connected to the electronic switch (TR) and to the first and second detector means and arranged to bring about the starting of the rotation of the rotor (R), starting from a predetermined initial position (θ a) driving the electronic switch (TR) in a manner such as to bring about the passage through the stator winding (W) of a first current pulse (I b) checking if the back-electromotive force (E) consequently developed in the stator winding (W) has a first zero-crossing within a predetermined period of time (T) which immediately precedes the third zero-crossing of the supply voltage (V) after the start of the first current pulse (I c) when the above-mentioned check provides a positive outcome, driving the electronic switch (TR) in a manner such as to bring about the passage through the stator winding (W) of a second current pulse (I d) when the check provides a negative outcome, repeating the procedure of step a) given above from the beginning, reducing the duration of the first delay (t