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Browse Prior Art Database

Variable Torque Constant Motor Driver

IP.com Disclosure Number: IPCOM000117361D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Glaess, DF: AUTHOR [+5]

Abstract

A motor driver design using a closed loop feedback feature to compensate for operating conditions by controlling the average torque constant of a motor to minimize power usage is disclosed. The average motor torque constant is controlled by varying the point in time that the windings are commutated.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Variable Torque Constant Motor Driver

      A motor driver design using a closed loop feedback feature to
compensate for operating conditions by controlling the average torque
constant of a motor to minimize power usage is disclosed.  The
average motor torque constant is controlled by varying the point in
time that the windings are commutated.

      This invention provides a method by which the torque constant
(Kt) of a motor can be varied under control of the spindle motor
driver.  This allows the designer to in "real time" tune the Kt for a
given operating condition, maximizing Kt.  The benefit is lower
average power for the population of files.

      The Figure shows the method invented to vary the average torque
constant of a motor.  A conventional motor controller will commutate
the motor at point A, commutating at this point yields the highest
average torque a motor can provide.  The Figure goes on to show how
by skewing the commutation point from Point A to point B, the average
Kt can be lowered.  There are motor controllers that presently
provide a digital input to control the commutation skew.  This skew
input is typically set once to maximize the torque of the motor.
There are several feedback control loops that can be used to
determine what value the skew should be set to for given operating
conditions.  One such method would be to monitor the drive current
requested by the speed control loop.  If the requested current
exceeds a predetermin...