Abstract: A driving apparatus drives a brushless motor that includes a plurality of windings. The apparatus comprises a plurality of switch half-bridges connected to a power line and to the windings, a memory adapted to contain a plurality of signal profiles to be cyclically applied to the plurality of windings of the motor, a multiplier for multiplying the profile values of the signals from the memory by a scale factor, a control circuit adapted to generate PWM signals for the switches of the plurality of switch half-bridges according to values output by the multiplier, a polarity detector configured to detect the polarity of the current passing trough at least one winding of the motor and a scale factor controller configured to modify the scale factor according to the detected current polarity and so as to make each signal profile to be applied to each winding of the motor either higher than the back-electromotive force or equal to the back-electromotive force generated by the motor.

Abstract: A driving apparatus for an electromagnetic load, said apparatus having at least one pair of first and second transistors arranged so as to form a current path with the electromagnetic load for discharging the current produced by the electromagnetic load. The first transistor has an inherent diode between the non-drivable terminals and the apparatus is configured to control switching of the pair of first and second transistors, to diode-connect the second transistor, with said first and second transistors switched off, so that the current produced by said electromagnetic load, crossing said inherent diode, creates an overvoltage between the terminals of the second diode-configured transistor such to exceed the conduction threshold voltage thereof.

Abstract: The method and a related device are for driving a brushless motor, according to which by acting solely on the control value, that is by reducing or increasing it, the driving mode eventually passes from a sinusoidal three-phase driving mode to a distorted square-wave three-phase driving mode for increasing or maximizing the voltage that may be supplied to each motor winding or vice versa. An effective drive voltage profile includes, cyclically, during each 60 electrical degree interval, profiles of re-constructed outphased complete drive waveforms including a first one stably in a saturated region, a second one exiting, at the beginning of the interval, a state of incipient saturation, and a third one reaching, at the end of the interval, a state of incipient saturation. In this way, by modifying the numerical control value it is possible to pass from a sinusoidal drive mode to a distorted drive mode of enhanced maximum peak value or vice versa.

Abstract: A device for the change of the driving mode of an electromagnetic load from a first operating mode with pulse width modulation to a second operating mode that is linear by means of switching circuits. During a first operating mode, each of two outputs has a voltage value ranging from a first reference voltage to a second reference voltage. The device adapted to synchronize a change command signal from a first operating mode to a second operating mode of the electromagnetic load with the signal representative of the flow of current circulating within the load at substantially its average value and adapted to generate a first command signal in response to the synchronization.

Abstract: A method and circuit to stop a spindle motor in the absence of the external supply voltage in which the spindle motor is structured to move a hard disk provided with at least one reading or writing head moved by a voice coil motor, the spindle motor provided with a plurality of coils. The method includes rectifying the backelectromotive force of the spindle motor to produce a braking current, driving the voice coil motor with at least a portion of the braking current until the speed of the spindle motor becomes lower than a predetermined stop speed, and, after the parking of the at least one reading or writing head of the voice coil motor, stopping the spindle motor by short-circuiting the coils of the spindle motor.

Abstract: Energy recovery during recirculation phases of the phase windings of a multiphase spindle motor is increased when all the MOSFETs of the output bridge stage associated therewith are turned off (tristated) for charging a hold capacitor. This is accomplished by allowing the recirculation of the motor currents through the same MOSFETs of the output bridge stage that are turned on during the current recirculation phases. Recirculation of the currents and the charging of the hold capacitor takes place through fully saturated power MOSFETs.

Abstract: An embodiment of a motor controller includes a motor driver and a signal conditioner. The motor driver is operable to generate a motor-coil drive signal having a first component at a first frequency, and the signal conditioner is coupled to the motor driver and is operable to alter the first component. For example, if the first component of the motor-coil drive signal causes the motor to audibly vibrate (e.g., “whine”), then the signal conditioner may alter the amplitude or phase of the first component to reduce the vibration noise to below a threshold level.

Abstract: A control circuit for a full-bridge-stage to drive an electric load includes PWM generation circuitry for generating first and second PWM signals so that a difference between duty-cycles of the PWM signals represents an amplitude of a drive current. A logic XOR gate is input with the first and second PWM signals and generates a logic XOR signal. A logic sampling circuit generates a logic driving command of a half-bridge of the full-bridge stage, a logic value of which corresponds to a sign of the drive current, by sampling one of the first and second PWM signals based upon active switching edges of the logic XOR signal. A second XOR gate is input with the logic XOR signal and the logic driving command and generates a third PWM driving signal of the other half-bridge of the full-bridge stage, a duty-cycle of which corresponds to the amplitude of the drive current.

Abstract: An apparatus is provided for powering at least one electric motor. The apparatus includes at least one driving device for driving the electric motor, a supply path positioned between a supply voltage generator and the at least one driving device, a first circuit, a control device, and a protection device for protecting against over-voltages. The first circuit is inserted in the supply path to enable and prevent the powering of the at least one driving device, and the control device controls at least the first circuit. The protection device includes a second circuit for detecting a current that flows in the supply path from the at least one driving device to the supply voltage generator, and a third circuit for selectively absorbing the current that is detected.

Abstract: The present invention refers to an apparatus for driving an electromagnetic load. The apparatus comprises a power stage comprising at least one first and one second transistor half-bridge and the electromagnetic load is arranged between the first and the second half-bridge. The apparatus comprises a first and a second device suitable for driving in linear modality respectively the first and the second half-bridge and another device suitable for driving in pulse width modulation modality the first half-bridge, first switch means suitable for connecting the first half-bridge to the first device or to the other device in response to a control signal, second switch means suitable for connecting the second half-bridge to the second device in response to the control signal.

Abstract: A method of driving a sensorless brushless motor in PWM mode includes tristating a winding during a time window for detecting a zero-cross of the back electromotive force induced in the winding by rotation of a rotor, monitoring voltage of the tristated winding during an unmasked portion of the time window, and detecting during the time window a zero-cross event of the induced back electromotive force. The method includes verifying whether the zero-cross event occurred during the unmasked portion, modifying for the next cycle the duration of the time window and/or of the unmasked portion thereof based upon the verification, defining a safety interval in the unmasked time window, modifying the duration of the time window and/or of the unmasked portion thereof depending on whether the zero-cross event has been detected during the safety interval.

Abstract: The method and a related device are for driving a brushless motor, according to which by acting solely on the control value, that is by reducing or increasing it, the driving mode eventually passes from a sinusoidal three-phase driving mode to a distorted square-wave three-phase driving mode for increasing or maximizing the voltage that may be supplied to each motor winding or vice versa. An effective drive voltage profile includes, cyclically, during each 60 electrical degree interval, profiles of re-constructed outphased complete drive waveforms including a first one stably in a saturated region, a second one exiting, at the beginning of the interval, a state of incipient saturation, and a third one reaching, at the end of the interval, a state of incipient saturation. In this way, by modifying the numerical control value it is possible to pass from a sinusoidal drive mode to a distorted drive mode of enhanced maximum peak value or vice versa.

Abstract: Energy recovery during recirculation phases of the phase windings of a multiphase spindle motor is increased when all the MOSFETs of the output bridge stage associated therewith are turned off (tristated) for charging a hold capacitor. This is accomplished by allowing the recirculation of the motor currents through the same MOSFETs of the output bridge stage that are turned on during the current recirculation phases. Recirculation of the currents and the charging of the hold capacitor takes place through fully saturated power MOSFETs.

Abstract: A method of preventing concurrent or quasi-concurrent commutations of a pair of phase shift modulation (PSM) drive signals of an output bridge stage driving an electrical load includes establishing a threshold level of a programmed current level to be transmitted though the electrical load. The method also includes, if the programmed current level is lower than the threshold level, enhancing a time offset between commutation edges of the pair of PSM drive signals by a minimum time.

Abstract: A method for sensing a back electromotive force induced in a winding of a voice coil electro-mechanical actuator controlled in a discontinuous mode by alternating conduction phases to off-phases includes sensing voltage at terminals of the winding during an off-phase The winding is driven during a conduction phase immediately preceding the off-phase to invert, during a final portion of the conduction phase before entering an off-phase, a direction of flow of the current through the winding.

Abstract: The invention relates to a system for controlling the power dissipated by a power stage working in mixed Linear/PWM mode, for driving an electromagnetic load, the power stage comprising a power amplifier incorporating a bridge-like circuit, with a half bridge controlled in PWM mode and another half bridge controlled in linear mode, respectively by a converter block and by an error amplifier and wherein the electromagnetic load is crossed by a current and generates an electromotive force, the control system further comprising a first amplifier of a voltage drop, calculated on a sensing resistance of the electromagnetic load, whose output signal is further applied by a second amplifier. Advantageously, according to the invention, the Linear half bridge is controlled directly by an input voltage drawn from an input node outside the current control loop.

Abstract: A method for sensing a back electromotive force induced in a winding of a voice coil electro-mechanical actuator controlled in a discontinuous mode by alternating conduction phases to off-phases includes sensing voltage at terminals of the winding during an off-phase The winding is driven during a conduction phase immediately preceding the off-phase to invert, during a final portion of the conduction phase before entering an off-phase, a direction of flow of the current through the winding.

Abstract: A system controls the speed of a Voice Coil Motor (VCM) in order to perform the ramp loading of hard disk heads with low noise. This system includes a generator for generating a discontinuous PWM drive signal to a power stage. A sampling block is clocked by a synchronization signal issued from the generator and receives as an input a signal related to the electromotive force (Bemf) provided by the VCM motor. An adder node placed at the sampling block output receives a signal related to a reference electromotive force (Bemf_ref). A filtering block placed downstream of the adder node generates a power supply voltage signal to the power stage. The control system further includes a control block having at least one voltage divider and controlled switches. The control block is input the signal issued from the filtering block and control signals from the generator block to selectively operate the controlled switches and set the value of the power-on signal of the power stage.

Abstract: The present invention refers to an apparatus for driving an electromagnetic load. The apparatus comprises a power stage comprising at least one first and one second transistor half-bridge and the electromagnetic load is arranged between the first and the second half-bridge. The apparatus comprises a first and a second device suitable for driving in linear modality respectively the first and the second half-bridge and another device suitable for driving in pulse width modulation modality the first half-bridge, first switch means suitable for connecting the first half-bridge to the first device or to the other device in response to a control signal, second switch means suitable for connecting the second half-bridge to the second device in response to the control signal.

Abstract: An apparatus is provided for powering at least one electric motor. The apparatus includes at least one driving device for driving the electric motor, a supply path positioned between a supply voltage generator and the at least one driving device, a first circuit, a control device, and a protection device for protecting against over-voltages. The first circuit is inserted in the supply path to enable and prevent the powering of the at least one driving device, and the control device controls at least the first circuit. The protection device includes a second circuit for detecting a current that flows in the supply path from the at least one driving device to the supply voltage generator, and a third circuit for selectively absorbing the current that is detected.