Patent application number | Description | Published |
20080303458 | ENHANCEMENT OF THE EFFICIENCY OF ENERGY RECOVERY DURING SPINDLE MOTOR STEP-UP PHASES FOR PARKING THE R/W HEAD OF A DISK STORAGE DEVICE UPON EXTERNAL SUPPLY FAILURE - 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. | 12-11-2008 |
20090026990 | METHOD AND DEVICE FOR DRIVING A BRUSHLESS MOTOR WITH VOLTAGE WAVEFORM PREDISPOSED FOR A PROGRESSIVE AND AUTOMATIC SWITCHING FROM A THREE-PHASE SINUSOIDAL DRIVING TO A SQUARE WAVE THREE-PHASE DRIVING - 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. | 01-29-2009 |
20090033263 | METHOD AND RELATED CIRCUIT FOR DRIVING A SENSORLESS BRUSHLESS MOTOR - 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. | 02-05-2009 |
20100001667 | CONTROL CIRCUIT OF A FULL-BRIDGE STAGE - 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. | 01-07-2010 |
20100052585 | MOTOR CONTROLLER WITH DRIVE-SIGNAL CONDITIONING - 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. | 03-04-2010 |
20100244761 | DEVICE TO SYNCHRONIZE THE CHANGE OF THE DRIVING MODE OF AN ELECTROMAGNETIC LOAD - 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. | 09-30-2010 |
20100246051 | STOPPING METHOD FOR A SPINDLE MOTOR AND RELATED DEVICE - 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. | 09-30-2010 |
20110074374 | DRIVING APPARATUS FOR AN ELECTROMAGNETIC LOAD AND RELATED METHOD - 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. | 03-31-2011 |
20110156622 | DRIVING APPARATUS FOR ELECTRIC MOTOR AND RELATED METHOD - 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. | 06-30-2011 |
20120161678 | MANAGEMENT APPARATUS OF A ROTATING MOTOR AND AN ANNEXED LOAD DURING POWER LOSS - A management apparatus is described of a rotating motor and a load during power loss; the apparatus comprises a first switching circuit coupled with the rotating motor and a controller of said first switching circuit. The controller is configured to drive the first switching circuit so as to convert a back-electromotive force voltage developed in the rotating motor into a power supply voltage for the load. The first switching circuit is driven in accordance with a first duty cycle. The apparatus comprises a second switching circuit coupled with the load and driven in accordance with a second duty cycle. The controller is configured to vary said first and said second duty cycles to keep the power supply voltage for the load above or equal to a threshold voltage. | 06-28-2012 |
20150022128 | METHOD AND RELATED DRIVER OF A PERMANENT MAGNET SYNCHRONOUS ELECTRIC MOTOR - A method of driving a permanent magnet synchronous electric motor includes sensing or estimating a back electromotive force induced in at least a winding of the motor by the rotation of a rotor of the motor; and reading, from a memory, values of a first voltage waveform having a phase angle with respect to the back electromotive force. The method also includes generating a driving voltage corresponding to the sum of values of a control voltage, obtained as product of the values of the first voltage waveform by a first coefficient determined as a function of a desired value of motor torque, and values of a cancelation voltage of the back electromotive force. The method also includes applying the driving voltage at the motor winding. | 01-22-2015 |