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Damping Technique for Stepper Motor Chopper Drivers

IP.com Disclosure Number: IPCOM000120256D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Grady, PE: AUTHOR

Abstract

Disclosed is a method of stepper motor control that increases rotor damping when used with fixed current chopper drivers. The method is effective during motor acceleration, deceleration, and slewing, especially at mid frequency stepping rates that normally exhibit uncontrollable rotor oscillations. This method is an extension of damping techniques that short one of the motor windings when stopping at a particular pole (*). The back EMF of the shorted winding produces a current which dampens the rotor oscillations. By properly timing the state advances, the shorted winding technique can also be used while the stepping motor is running, not only on the last step. The amount of damping depends on the motor parameters, the circuit resistance, and the duration of each shorting cycle.

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Damping Technique for Stepper Motor Chopper Drivers

      Disclosed is a method of stepper motor control that
increases rotor damping when used with fixed current chopper drivers.
The method is effective during motor acceleration, deceleration, and
slewing, especially at mid frequency stepping rates that normally
exhibit uncontrollable rotor oscillations.  This method is an
extension of damping techniques that short one of the motor windings
when stopping at a particular pole (*).  The back EMF of the shorted
winding produces a current which dampens the rotor oscillations.  By
properly timing the state advances, the shorted winding technique can
also be used while the stepping motor is running, not only on the
last step.  The amount of damping depends on the motor parameters,
the circuit resistance, and the duration of each shorting cycle.

      Table 1 lists the phase states necessary to use the damping
technique with any combination of half stepping and full stepping
with either one or two phases energized.  The table contains the
eight states normally associated with four-phase stepping motors,
plus four additional states for damping.  Although states 4, 8, 12,
and 16 are identical to states 3, 5, 11, and 15, respectively, they
are included so that modulo 16 arithmetic can be used for phase
advances. See Table 1.

      The damping states must not be activated until after the
current in the non-energized winding decays to zero; otherwise, an
uncontroll...