Abstract: The driver circuit (10) comprises a first triac or the like (11) for connection in series with the stator winding (5, 6) of the motor between the terminals (12, 13) of an alternating-current voltage supply, the gate of the first triac (11) being arranged for connection to an intermediate point (C) of the stator winding (5, 6) of the motor (M). A second triac or the like (15) is connected between the intermediate point (C) of the winding (5, 6) and the terminal (13) of the voltage supply to which the first triac (11) is connected. A control circuit (15-27) is connected to the gate of the second triac (15) such that, each time the motor (M) is connected to the voltage supply, it initially makes the second triac (15) conductive and consequently cuts off the first triac (11) for a predetermined initial period of time. and cuts off the second triac (15) and allows the first triac (11) to become conductive after this period of time.

Abstract: The system comprises sensors (PS) for detecting the angular position of the rotor (R) of the motor and a driver circuit (DC) arranged to control conduction in the controlled switches (SW) associated with the phases (W) of the motor and in a regulation switch (RSW) in predetermined manner in dependence on the position signals emitted by the sensors (PS). The regulation switch (RSW) is driven in an on/off manner by means of a square-wave signal. The system further comprises a protection circuit (PC) with a capacitor (C) connected to the control input of the regulation switch (RSW) so that the capacitor (C) is charged each time the regulation switch (RSW) is made conductive by the square-wave signal in operation, and with a control switch (T) connected between the control input of the regulation switch (RSW) and a pole (GND) of the direct-current supply and having a control input connected to the capacitor (C).

Abstract: The motor comprises a rotor with permanent magnets with at least one pair of poles, a stator having a winding wound around a magnetic circuit, position-detectors for providing driving signals in dependence on the angular position of the rotor, and a driver circuit for controlling the flow of current in the stator winding in dependence on the signals supplied by the position-detectors. The winding is divided into a first half-winding and a second half-winding wound around the magnetic circuit in opposite directions. The driver circuit comprises first and second controlled switches in series with the first stator half-winding and with the second stator half-winding, respectively, in respective circuit branches arranged in parallel between the supply terminals.

Abstract: A device for controlling a synchronous electric motor with a permanent magnet rotor. The device comprises a stator including a winding disposed around a stack of laminations and with which is associated a permanent magnet rotor. Controlled conductor devices are connected to the stator winding and to an AC source. One or more position sensors determine the application to the control inputs of the said controlled conductor devices of electrical control signals having to states which vary as a function of the angular position of the rotor. The arrangement is such that the current is caused to flow in the stator winding in a direction which depends only on the polarity of the voltage of the source and the instantaneous position of the rotor.

Abstract: The driver circuit (10) comprises a first triac or the like (11) for connection in series with the stator winding (5, 6) of the motor between the terminals (12, 13) of an alternating-current voltage supply, the gate of the first triac (11) being arranged for connection to an intermediate point (C) of the stator winding (5, 6) of the motor (M). A second triac or the like (15) is connected between the intermediate point (C) of the winding (5, 6) and the terminal (13) of the voltage supply to which the first triac (11) is connected. A control circuit (15-27) is connected to the gate of the second triac (15) such that, each time the motor (M) is connected to the voltage supply, it initially makes the second triac (15) conductive and consequently cuts off the first triac (11) for a predetermined initial period of time, and cuts off the second triac (15) and allows the first triac (11) to become conductive after this period of time.

Abstract: The system comprises sensors (PS) for detecting the angular position of the rotor (R) of the motor and a driver circuit (DC) arranged to control conduction in the controlled switches (SW) associated with the phases (W) of the motor and in a regulation switch (RSW) in predetermined manner in dependence on the position signals emitted by the sensors (PS). The regulation switch (RSW) is driven in an on/off manner by means of a square-wave signal. The system further comprises a protection circuit (PC) with a capacitor (C) connected to the control input of the regulation switch (RSW) so that the capacitor (C) is charged each time the regulation switch (RSW) is made conductive by the square-wave signal in operation, and with a control switch (T) connected between the control input of the regulation switch (RSW) and a pole (GND) of the direct-current supply and having a control input connected to the capacitor (C).