Abstract: A data storage device is disclosed comprising a first voice coil motor (VCM) comprising a first voice coil configured to actuate a first head over a first disk, and a second VCM comprising a second voice coil configured to actuate a second head over a second disk. The data storage device further comprises a spindle motor configured to rotate the first and second disk, wherein during a power failure the first and second disks rotating causes the spindle motor to generate a back electromotive force (BEMF) voltage. During the power failure, the BEMF voltage is applied to the first VCM and to the second VCM during a first interval. The BEMF voltage is monitored, and when the BEMF voltage falls below a first threshold, the BEMF voltage is disconnected from the first VCM and the second VCM during a second interval.

Abstract: A data storage device is disclosed wherein multiple voice coil motors (VCMs) are unloaded using a back electromotive force (BEMF) voltage generated by a spindle motor. A velocity and position of each VCM is measured, and a priority assigned to each VCM based on the measured velocity and position. During a delay interval, the BEMF voltage is used to apply a first brake voltage to a high priority VCM and to apply a second brake voltage to a low priority VCM, wherein the second brake voltage is lower than the first brake voltage. After the delay interval, the BEMF voltage is used to apply the first brake voltage to the high priority VCM and to apply a third brake voltage to the low priority VCM, wherein the third brake voltage is higher than the second brake voltage.

Abstract: The driving voltage of the motor is incremented a quantity proportional to the speed of the motor according to a proportionality factor that is adjusted to compensate the back electromotive force. A method includes open-loop voltage control of a DC motor having a certain design speed constant, through a driving signal that is determined for imparting a certain acceleration to the motor and by generating a driving voltage of an output power stage to which the winding of the motor is connected as a function of the driving signal.

Abstract: A method for determining an effective resistance of a voltage controlled DC motor having a nominal resistance includes driving the DC motor with a signal so that the DC motor has a targeted acceleration, and sensing an effective acceleration of the DC motor. The effective resistance of the DC motor is determined as a function of the nominal resistance, the targeted acceleration and the effective acceleration.

Abstract: A method of driving an electrical load having a complex electrical impedance, such as a voice-coil motor controlling the position of a read/write head in a data storage disk drive system, comprises providing a voltage-mode driver generating drive signals for the electrical load in response to drive commands. Compensated commands for the voltage-mode driver are generated filtering the drive commands, compensating for a phase shift between electrical quantities delivered to the electrical load. The voltage-mode drive thus emulates a conventional, but more expensive, current-mode drive. In a preferred embodiment, the method comprises estimating characteristic parameters of the electrical load during the operation, and adapting the filtering to the estimated characteristic parameters. The estimation comprises implementing a Kalman filtering algorithm, particularly an extended Kalman filtering.

Abstract: A method for determining an effective resistance of a voltage controlled DC motor having a nominal resistance includes driving the DC motor with a signal so that the DC motor has a targeted acceleration, and sensing an effective acceleration of the DC motor. The effective resistance of the DC motor is determined as a function of the nominal resistance, the targeted acceleration and the effective acceleration.

Abstract: The driving voltage of the motor is incremented a quantity proportional to the speed of the motor according to a proportionality factor that is adjusted to compensate the back electromotive force. A method includes open-loop voltage control of a DC motor having a certain design speed constant, through a driving signal that is determined for imparting a certain acceleration to the motor and by generating a driving voltage of an output power stage to which the winding of the motor is connected as a function of the driving signal.

Abstract: A method of driving an electrical load having a complex electrical impedance, such as a voice-coil motor controlling the position of a read/write head in a data storage disk drive system, comprises providing a voltage-mode driver generating drive signals for the electrical load in response to drive commands. Compensated commands for the voltage-mode driver are generated filtering the drive commands, compensating for a phase shift between electrical quantities delivered to the electrical load. The voltage-mode drive thus emulates a conventional, but more expensive, current-mode drive. In a preferred embodiment, the method comprises estimating characteristic parameters of the electrical load during the operation, and adapting the filtering to the estimated characteristic parameters. The estimation comprises implementing a Kalman filtering algorithm, particularly an extended Kalman filtering.