ETEL Doc. - Operation & Software Manual # DSC2P 903 / Ver. F / 3/6/05
Chapter C: System functions
Operation & Software Manual
Direct Drives & Systems
103
If the motor
PSA is not correct
, the motor will not give its maximum force. It can even happen that no force at
all is supplied, or even worse, the force is provided in the wrong direction.
If the motor phase shift is only between 1° to 5° off zero, the motor will still deliver around 95% of its nominal
force. A higher phase shift will significantly reduce the force.
You can see below that for a phase shift as bad as 90
°
to 270
°
off the correct value, a force is provided in the
wrong direction (with 180
°
the maximum force is provided in the wrong direction). In this case, the position loop
becomes unstable and the
motor speeds suddenly up in the wrong direction!
The expression used is:
“there is an inverted phase shift adjustment”.
This is the speed error v
e
which pushes the motor to speed up in the case of an inverted phase shift adjustment.
In a regular process, the position loop regulator usually tries to decrease v
e,
but as in our case the force F
provided by the motor is opposed to the reference force F
c
, the motor will move in the direction that tends to
increase v
e
rather than to decrease it.
12.7.1.4 Commutation look-up table parameters
The currents sent in the motor phases have a sinusoidal form. These types of current are calculated with the
current reference generator. It is important to remember that the motor look-up table has a sinusoidal function
period.
Parameter
K53
allows the user to have a repetitive adjustment after a homing:
• with an EnDat 2.1 encoder, parameter K53 is directly taken into account whatever the value of parameter
K52
(no homing is needed).
• AUT = 8 allows the user to find parameter K53 for all that K52 = 1 (refer to
for more information
about the AUT command).
Available on
DSC2P
DSC2V
DSCDP
DSCDL
DSCDM
K
Name
Value
Comment
K52
Look-up table mode
0
1
After a homing:
Leave out parameter K53
Replaces the phase shift adjustment by parameter K53
K53
Look-up table phase
adjustment
-
Motor phase shift adjustment value according to the ref. mark position
Bad phase shift adjustment
B-EMF in phase A
Force produced by phase A
phase shift
current in phase A
t
t
Phase shift error effect
phase shift
Force
+ 100%
- 100%
0
90°
180°
270°
360°