| 摘要 |
The control system comprises: a switch (TR) in series with a winding (W) of the motor (M) between two terminals (A, B) which are connected to a supply of an alternating voltage (V), a first detector circuit (1) suitable for providing a signal (V) indicative of the sign and of the zero-crossings of the alternating supply voltage (V), a second detector means (2, 3) suitable for providing signals indicative of the sign and of the zero-crossings of the BEMF which is developed in the stator winding (W), and a control unit (MC) arranged to bring about the starting of the rotation of the rotor (R), starting from an initial position (Θ), in accordance with a procedure comprising the steps of: a) driving the switch (TR) in a manner such as to bring about the passage through the winding (W) of a first current pulse (I1) which starts with a first delay (t) relative to the immediately preceding zero-crossing of the supply voltage (V), b) checking if the BEMF (E) consequently developed in the winding (W) has a first zero-crossing within a predetermined period of time (T) which immediately precedes the third zero-crossing of the voltage (V) after the start of the first current pulse (I1), c) when the check provides a positive outcome, driving the switch (TR) in a manner such as to bring about the passage through the winding (W) of a second current pulse (I2) of opposite sign or direction to the first (I1), with a second predetermined delay (t2) relative to the third zero-crossing of the voltage (V), and then supplying to the winding (W) a voltage at the frequency of the supply, and d) when the check provides a negative outcome, repeating the procedure from the beginning starting from step a), reducing the duration of the first delay (t1) if the first zero-crossing of the BEMF (E) took place after the period of time (T) and increasing the duration of the first delay (t1) if the first zero-crossing of the BEMF (E) took place before the period of time (T). |
