Browse Prior Art Database

Variable Servo Sampling for Multiple Motor Speed Control

IP.com Disclosure Number: IPCOM000119112D
Original Publication Date: 1997-Nov-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 73K

Publishing Venue

IBM

Related People

Fukushima, Y: AUTHOR [+2]

Abstract

Disclosed is a motor control method which is controlled by a Micro Processing Unit (MPU) in a Hard Disk Drive (HDD). This method can optimize servo stability and MPU overhead by changing the servo sampling number for several motor speeds.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 74% of the total text.

Variable Servo Sampling for Multiple Motor Speed Control

      Disclosed is a motor control method which is controlled by a
Micro Processing Unit (MPU) in a Hard Disk Drive (HDD).  This method
can optimize servo stability and MPU overhead by changing the servo
sampling number for several motor speeds.

      If the servo sampling number in a revolution is fixed at
several motor speeds, the following two problems appear:
  1.  The servo becomes unstable at a slower speed.
  2.  The servo calculation overhead of the MPU is increased at a
       faster speed.

      To optimize servo stability and calculation overhead, the servo
sampling number in a revolution should be changed properly as
follows:
  1.  At a slower speed, the servo sampling number should be
       increased for servo stability.
  2.  At a faster speed, the servo sampling number should be
       decreased for MPU overhead reduction.

      Fig. 1 shows an example of a block diagram of an HDD.  Phase
signal (1) is generated from back Electromotive Force (EMF) of Motor
(2) by Motor Driver (3).  So, the number of this phase signal is
fixed as a  value in a revolution and it depends on the motor
specification.  For example, Fig. 2 shows a phase signal of a motor
of which specification  is 3-phase and 8-pole.  This shows the number
of phase pulse is four in  a revolution.  Triggered by this phase
signal, MPU starts the calculation  of motor servo.  Usually, this
...