Browse Prior Art Database

Direct Access Storage Device Voice Coil Temperature Estimator and Limiter

IP.com Disclosure Number: IPCOM000113681D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Heminger, M: AUTHOR [+4]

Abstract

A method is described to control the temperature of a direct access storage device (DASD) actuator voice coil. Voice coil control current values are used to compute an estimate of coil temperature change, which is used to set the maximum seek profile velocity.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 55% of the total text.

Direct Access Storage Device Voice Coil Temperature Estimator and
Limiter

      A method is described to control the temperature of a direct
access storage device (DASD) actuator voice coil.  Voice coil control
current values are used to compute an estimate of coil temperature
change, which is used to set the maximum seek profile velocity.

      This method involves estimating the actuator voice coil
temperature change due to control current, and limiting the power
into the coil when the coil temperature may exceed a limit.  Much of
the current applied to the actuator voice coil during a seek results
in resistive heating effects, and may cause temperatures above the
coil design limit if high operation rates and seek power input were
maintained.  This method limits power input to the voice coil to
prevent device failure due to high coil temperatures, without
affecting seek performance of bursts of high operation rates when the
estimated temperature remains below limits.

      Given the amount of current (I) and the coil design resistance
(R), the power transferred to the voice coil can be estimated, and is
summed every servo sample period:
                   P = sum I sup 2 R

      The power transferred to the coil results in heating the coil.
A heat transfer rate (Q) and thermal time constant (tau) for the DASD
device are determined empirically.  The coil temperature (Tc) is
estimated once every thermal sample time (T), in this case...