News Column

Patent Issued for Method and Apparatus for Controlling a Motor

August 5, 2014



By a News Reporter-Staff News Editor at Journal of Technology -- A patent by the inventor Chung, Da-woon (Suwon-si, KR), filed on March 22, 2011, was published online on July 22, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8786974 is assigned to Seagate Technology International (Grand Cayman, KY).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The inventive concept relates to a method and apparatus for controlling a motor, and more particularly, to a method and apparatus for adaptively controlling a motor by considering a state of disturbance applied to a system.

"A disk drive is a type of data storage device. A disk drive rotates a disk using a spindle motor, and writes data into disk or reads data from the disk by using a head. The manner in which the spindle motor is controlled affects data reading and/or writing performance of the disk drive."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "Embodiments of the inventive concept provide a method of adaptively controlling a motor by considering a state of disturbance applied to a system. Embodiments of the inventive concept also provide an apparatus for adaptively controlling a motor by considering a state of disturbance applied to a system. Embodiments of the inventive concept also provide a disk drive using a method of adaptively controlling a motor that rotates a disk by considering a state of disturbance applied to a system. In addition, embodiments of the inventive concept provide a storage medium on which program code is recorded for executing a method of adaptively controlling a motor by considering a state of disturbance applied to a system.

"According to an aspect of the inventive concept, there is provided a method of controlling a motor in a head disk assembly. The method includes changing a frequency bandwidth of a frequency response characteristic in a motor control system according to a state of a disturbance applied to the motor control system, and controlling a speed of the motor by applying the changed frequency bandwidth to the motor control system.

"The motor may include a spindle motor for rotating a disk. Also, the method may further include determining the state of disturbance using at least one factor value based on at least one of a disturbance value detected by a shock detecting sensor, an amount of interference generated between a head and a disk, a difference between a measured speed of the motor and a target speed, and a jitter value of a spindle motor. The frequency bandwidth of the frequency response characteristic in the motor control system may be changed based on the determination.

"Changing the frequency bandwidth may include increasing the frequency bandwidth in proportion to an amplitude of the disturbance applied to the motor control system. Changing the frequency bandwidth may include setting the frequency bandwidth to a first frequency bandwidth when an amplitude of the disturbance applied to the motor control system exceeds an initially set threshold value, and otherwise setting the frequency bandwidth to a second frequency bandwidth, which is less than the first frequency bandwidth.

"Changing the frequency bandwidth may include setting the frequency bandwidth to a first frequency bandwidth while a disk drive having a ramp loading system is in a ramp loading period, and setting the frequency bandwidth to a second frequency bandwidth smaller than the first frequency bandwidth while the disk drive is in a data read or write operation period. Changing the frequency bandwidth may include setting the frequency bandwidth to a first frequency bandwidth until a first seek operation according to a ramp loading operation of a disk drive having a ramp loading system is completed, and setting the frequency bandwidth to a second frequency bandwidth smaller than the first frequency bandwidth after the first seek operation is completed.

"According to another aspect of the inventive concept, there is provided an apparatus for controlling a motor, including a speed detector for detecting a speed of the motor, multiple motor controllers, a selector, and a motor driver. Each of the motor controllers generates a speed control signal to reach a target speed based on the detected speed of the motor, according to frequency response characteristics of different frequency bandwidths. The selector selects one of the motor controllers based on a disturbance that generates a load variation of the motor. The motor driver generates a driving current based on the speed control signal generated by the motor controller selected by the selector, and applies the generated driving current to the motor.

"The selector may select a motor controller that has a frequency response characteristic of a relatively large frequency bandwidth that is proportional to an amplitude of the disturbance that generates the load variation of the motor.

"The motor controllers may include a first motor controller having a frequency response characteristic of a first frequency bandwidth, and a second motor controller having a frequency response characteristic of a second frequency bandwidth smaller than the first frequency bandwidth. The selector may select the first motor controller when an amplitude of the disturbance generating the load variation of the motor exceeds a threshold value, and may select the second motor controller when the amplitude of the disturbance generating the load variation of the motor does not exceed the threshold value. The amplitude of the disturbance generating the load variation of the motor exceeding the threshold value may result form a ramp loading executing condition in a disk drive having a ramp loading system.

"The selector may selects one of the motor controllers based on a state of the disturbance determined using at least one factor value based on at least one of a disturbance value detected by a shock detecting sensor, an amount of interference generated between a head and a disk, a difference between a measured speed of the motor and a target speed, and a jitter value of a spindle motor.

"According to another aspect of the inventive concept, there is provided an apparatus for controlling a motor, including a speed detector for detecting a speed of the motor, a subtractor for subtracting a speed error corresponding to a difference between the detected speed of the motor and a target speed, and a speed controller for generating a speed control signal corresponding to the speed error. The apparatus further includes a filter for changing a frequency bandwidth based on a disturbance generating a load variation of the motor, and for filtering and outputting the speed control signal according to a frequency response characteristic of the changed frequency bandwidth, and a motor driving unit for generating a driving current corresponding to the speed control signal filtered and output by the filter, and for supplying the driving current to the motor.

"The filter may include low pass filter. The filter may filter according to a frequency response characteristic of a first frequency bandwidth when an amplitude of the disturbance generating the load variation of the motor exceeds a threshold value, and may filter according to a frequency response characteristic of a second frequency bandwidth smaller than the first frequency bandwidth when the amplitude of the disturbance generating the load variation of the motor does not exceed the threshold value. The amplitude of the disturbance generating the load variation of the motor exceeding the threshold value may result from a ramp loading executing condition in a disk drive having a ramp loading system.

"According to another aspect of the inventive concept, there is provided a disk drive including a disk for storing information, a spindle motor for rotating the disk, and a spindle motor controller for changing a frequency bandwidth based on a disturbance condition generating a load variation of the spindle motor, and for generating a speed control signal based on a difference between a speed of the spindle motor and a target speed by applying a frequency response characteristic of the changed frequency bandwidth. The disk drive further includes a spindle motor driving unit for generating a driving current corresponding to the speed control signal and for applying the generated driving current to the spindle motor.

"The frequency bandwidth may be determined to be a first frequency bandwidth when the amplitude of the disturbance condition changing the load of the spindle motor exceeds a threshold value, and may be determined to be a second frequency bandwidth smaller than the first frequency bandwidth when the amplitude of the disturbance condition changing the load of the spindle motor does not exceed the threshold value.

"The spindle motor controller may determine the frequency bandwidth to be a first frequency bandwidth during a ramp loading executing period, where a head mounted on a ramp structure of the disk drive is moved onto the disk. The spindle motor controller may determine the frequency bandwidth to be in a second frequency bandwidth smaller than the first frequency bandwidth after the ramp loading executing period.

"According to another aspect of the inventive concept, there is provided a computer readable storage medium on which program code is recorded for executing a method of controlling a motor. The method includes changing a frequency bandwidth of a frequency response characteristic in a motor control system according to a state of disturbance applied to the motor control system, and controlling a speed of the motor by applying the changed frequency bandwidth to the motor control system."

URL and more information on this patent, see: Chung, Da-woon. Method and Apparatus for Controlling a Motor. U.S. Patent Number 8786974, filed March 22, 2011, and published online on July 22, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8786974.PN.&OS=PN/8786974RS=PN/8786974

Keywords for this news article include: Seagate Technology International.

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Source: Journal of Technology


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