Abstract: Controller for a three-phase brushless D.C. motor has a full bridge circuit and an electronic control unit (ECU). The full bridge circuit has three branches each with switches connected to the motor windings. The switches are driven by signals from the ECU. The drive signals are arranged in two sets of three signals. The two sets are offset by 180 electrical degrees. The drive signals of each set are offset by 120 electrical degrees and each have an active portion, alternating with an inactive portion. The active portion includes an initial interval of pulsed activation, an intermediate interval of continuous activation, and a final interval of pulsed activation. The active portion of the drive signals is greater than 120 electrical degrees, with each initial interval of pulsed activation of a switch overlapping the final interval of the previously activated switch.

Abstract: The system has a driving circuit for the motor of the electric fan, coupled to the electrical system of a motor vehicle and having a plurality of controlled electronic switches, and an electronic control unit arranged to control the driving circuit in such a way as to cause the flow in the motor of a variable average current capable of producing a required speed of rotation, in accordance with a predetermined relationship or function. The control unit is designed to store a predetermined threshold of rotation speed, and to control the motor through the associated driving circuit in such a way that when the rotational speed of the motor exceeds the threshold the driving circuit causes electrical braking of the motor.

Abstract: A control circuit for an electric fan, has a MOSFET transistor connected essentially in series with the motor of an electric fan between the two terminals of a first D.C. voltage source and having its source terminal connected to the motor; a transistor driving stage, having an input intended to receive a pulse-width modulation control signal and an output connected to the gate terminal of the MOSFET transistor, and a bootstrap capacitor connected between a second D.C. voltage source and the source terminal of the MOSFET transistor. A controlled electronic switch having a parallel-connected diode for conducting current from the bootstrap capacitor to the motor is arranged between the bootstrap capacitor and the source terminal of the MOSFET transistor. The electronic switch has a control input or gate connected to the output of the transistor driving stage.

Abstract: Controller for a three-phase brushless D.C. motor has a full bridge circuit and an electronic control unit (ECU). The full bridge circuit has three branches each with switches connected to the motor windings. The switches are driven by signals from the ECU. The drive signals are arranged in two sets of three signals. The two sets are offset by 180 electrical degrees. The drive signals of each set are offset by 120 electrical degrees and each have an active portion, alternating with an inactive portion. The active portion includes an initial interval of pulsed activation, an intermediate interval of continuous activation, and a final interval of pulsed activation. The active portion of the drive signals is greater than 120 electrical degrees, with each initial interval of pulsed activation of a switch overlapping the final interval of the previously activated switch.

Abstract: The system has a driving circuit for the motor of the electric fan, coupled to the electrical system of a motor vehicle and having a plurality of controlled electronic switches, and an electronic control unit arranged to control the driving circuit in such a way as to cause the flow in the motor of a variable average current capable of producing a required speed of rotation, in accordance with a predetermined relationship or function. The control unit is designed to store a predetermined threshold of rotation speed, and to control the motor through the associated driving circuit in such a way that when the rotational speed of the motor exceeds the threshold the driving circuit causes electrical braking of the motor.

Abstract: A circuit comprises at least one electronic switch which is operatively connected to an inductive load, is intended to be driven by means of an on-off signal and, in an enabled condition, can connect the load to a direct-current voltage supply, at least one freewheeling circuit branch which comprises a diode and can recirculate the transient current which flows through the load each time the switch is disabled, and a filtering circuit connected between the diode and the voltage supply and comprising a parallel capacitor connected to the diode and a series inductor connected between the diode and the voltage supply. The freewheeling circuit branch and the filtering circuit are connected substantially in series with one another in a circuit branch which is operatively connected in parallel with the load.