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US 7,675,255 B2Granted
Back EMF reduction in a storage drive using pulse width modulation in a closed loop motor control system
AssigneeInternational Business Machines Corporation
InventorsAllen K. Bates, Nhan Xuan Bui, Reed A. Hancock, Louis P. Russo
Life of this patent
Estimating the term…
Abstract
A storage drive implements a method for a BEMF voltage reduction during a deceleration period of an electric motor of the storage drive. In operation, the electric motor is disconnected from a power supply during an entirety of the deceleration period of the electric motor to prevent any flow of a BEMF current into the power supply, and the electric motor is connected to a power return during a segment or an entirety of the deceleration period of the electric motor to dissipate any BEMF voltage within the electric motor.
Claims17
A method for a BEMF voltage reduction in a storage device including an electric motor, the method comprising:
- selectively coupling by a motor controller, a winding power output of a plurality of winding power outputs of a power supply to an associated winding of an electric motor of a storage device during a servo operation period of said electric motor;
- disconnecting by the motor controller, all of the windings of the electric motor from all of the winding power outputs of the power supply during an entirety of a deceleration period of the electric motor to prevent any flow of a BEMF current into the winding power outputs of the power supply;
- providing by a servo controller in electrical communication with the motor controller, a BEMF control signal to the motor controller during the entirety of the deceleration period of the electric motor, wherein the BEMF control signal is representative of a comparison of a desired decelerated velocity profile of the electric motor and an actual decelerated velocity of the electric motor;
- connecting by the motor controller, at least one winding of the electric motor to a power return during at least a first segment of the deceleration period of the electric motor based on the BEMF control signal, to dissipate any BEMF voltage within the at least one winding of the electric motor;
- and
- disconnecting by the motor controller, the electric motor windings from the power return during a second segment of the deceleration period of the electric motor based on the BEMF control signal.
3 more elements
A storage drive, comprising:
- a storage medium adapted to store data therein;
- an electric motor adapted to move the storage medium, said electric motor having a plurality of windings;
- a power supply having a plurality of winding power outputs, each winding power output being associated with a winding of an electric motor to supply power to the associated winding;
- a power return;
- a motor controller wherein the motor controller is operable to disconnect the windings of the electric motor from the winding power outputs of the power supply during an entirety of a deceleration period of the electric motor to prevent any flow of a BEMF current into the winding power outputs of the power supply;
- and
- a servo controller in electrical communication with the motor controller and operable to provide a BEMF control signal to the motor controller during the entirety of the deceleration period of the electric motor, wherein the BEMF control signal is representative of a comparison of a desired decelerated velocity profile of the electric motor and an actual decelerated velocity of the electric motor;
- wherein the motor controller is further operable to connect at least one winding of the electric motor to the power return during at least a first segment of the deceleration period of the electric motor based on the BEMF control signal, to dissipate any BEMF voltage within the at least one winding of the electric motor;
- and
- wherein the motor controller is further operable to disconnect the electric motor from the power return during a second segment of the deceleration period of the electric motor based on the BEMF control signal.
7 more elements
A storage drive for use with a power supply and a power return, comprising:
- a storage medium adapted to store data therein;
- an electric motor adapted to move the storage medium;
- a motor controller wherein the motor controller is operable to disconnect the electric motor from the power supply during an entirety of a deceleration period of the electric motor to prevent any flow of a BEMF current into the power supply;
- and wherein the motor controller is further operable to connect the electric motor to the power return during at least a first segment of the deceleration period of the electric motor to dissipate any BEMF voltage within the electric motor;
- and
- a servo controller in electrical communication with the motor controller and operable to provide a BEMF control signal to the motor controller during the entirety of the deceleration period of the electric motor,
- wherein the BEMF control signal is representative of a comparison of a desired decelerated velocity profile of the electric motor and an actual decelerated velocity of the electric motor;
- wherein the motor controller is operable to connect the electric motor to the power return during the first segment of the deceleration period of the electric motor based on the BEMF control signal;
- and
- wherein the motor controller is operable to disconnect the electric motor from the power return during a second segment of the deceleration period of the electric motor based on the BEMF control signal.
7 more elements
An article of manufacture comprising a computer readable storage medium having code executed by a processor for performing operations to reduce a BEMF voltage in a storage drive including an electric motor, the operations comprising:
- selectively coupling by a motor controller, a winding power output of a plurality of winding power outputs of a power supply to an associated winding of an electric motor of a storage device during a servo operation period of said electric motor;
- disconnecting by the motor controller, all of the windings of the electric motor from all of the winding power outputs of the power supply during an entirety of a deceleration period of the electric motor to prevent any flow of a BEMF current into the winding power outputs of the power supply;
- providing by a servo controller in electrical communication with the motor controller, a BEMF control signal to the motor controller during the entirety of the deceleration period of the electric motor, wherein the BEMF control signal is representative of a comparison of a desired decelerated velocity profile of the electric motor and an actual decelerated velocity of the electric motor;
- connecting by the motor controller, at least one winding of the electric motor to a power return during at least a first segment of the deceleration period of the electric motor based on the BEMF control signal, to dissipate any BEMF voltage within at least one winding of the electric motor;
- and
- disconnecting by the motor controller, the electric motor from the power return during a second segment of the deceleration period of the electric motor based on the BEMF control signal.
3 more elements
Dependencies are inferred from the claim text.