PowerFlex Digital DC Drive User Manual -
Publication 20P-UM001C-EN-P - July 2008
C-22
Application Notes
Speed Zero Function
The Speed Zero Logic determines the behavior of the drive when the motor
is at zero speed. Refer to the Speed Adaptive and Speed Zero Logic block
diagram on
.
Configuring the Speed Zero Logic
It is possible to avoid drive creep when the motor is at zero speed by
disabling the Integral section of the Speed regulator. By default, the output
of the Integral portion of the Speed regulator is disabled (Par 123 [Spd Zero
I En] = 0 “Disabled”).
Important: If the speed regulator is disabled, the motor cannot receive a
load when it is stopped. Therefore this function is not suitable
for all applications!
Disable the output of the P gain of the Speed regulator by setting Par 126
[Spd Zero P Gain] to one of the following settings:
•
If the speed reference is above the value set in Par 106 [Ref Zero Level]:
Set Par 124 [Spd Ref Zero En] = 1 “Enabled”
•
If the speed reference and/or the reaction are above the value set in Par
106 [Ref Zero Level], set Par 124 [Spd Ref Zero En] = 0 “Disabled”
Par 124 [Spd Ref Zero En] is active only when Par 125 [Spd Zero P En] = 1
“Enabled”.
Set the P gain for zero speed:
•
If the P gain corresponds to the value set in Par 126 [Spd Zero P Gain],
then set Par 125 [Spd Zero P En] = 1 “Enabled”
•
If the P gain corresponds to the normal P gain, then set Par 125 [Spd
Zero P En] = 0 “Disabled”
The P gain at zero speed is set via Par 126 [Spd Zero P Gain] when Par 125
[Spd Zero P En] = 1 “Enabled”.
The threshold for the recognition of zero speed is determined by the value in
Par 106 [Ref Zero Level].
