Technology Option F01
08.2012
6SE7087-6QX70 (Version AN) Siemens AG
9-156
Compendium Motion Control
SIMOVERT MASTERDRIVES
9.8.7
Defining the actual value weighting factor (AVWF)
Commissioning step:
Check the resolution and value range of the actual position (P171):
In the factory setting, the resolution of the actual position value of the
motor encoder after shift division is 4096 steps per encoder revolution
[330.4]. This is adequate for most applications.
In some documents the german abreviation IBF may be used instead of
AVWF.
The following section describes exceptional circumstances where the
resolution has to be increased or reduced with P171 [330.3].
The resolution of the actual position on the encoder after shift division
and before multiplication by the AVWF P169/170 is 4096 increments
per encoder revolution in the factory setting. The rotor position KK090
[500 and 330.1] is resolved with 2
32
steps per encoder revolution. This
generates a positional value with 4096 increments per revolution as a
result of the shift division by 2
20
[330.4], due to the factory setting
P171 = 12, i.e. the resolution is 12 bits. You will find detailed
information on position detection in the section entitled "Position
sensing system for motor encoder".
Please note that although the actual position of the position sensing
system has a range of 2
32
LU, it is limited by the technology to a value
range of -999 999 999 ... +999 999 999 LU [815.4].
This resolution of the actual position value after shift division [330.3] of
4096 increments per motor revolution is exactly the same as the
resolution implemented by the measuring system with a 2-pole
resolver, and can virtually always remain unchanged when a resolver is
used. Only if extremely long traversing distances are involved, can it
become necessary to reduce the resolution (see following example):
Example where the position resolution must be reduced with
P171 < 12:
♦
LU = 1/4096th of an encoder revolution selected
♦
The traversing distance is over 244 000 encoder revolutions
♦
=> The traversing range would no longer fit into the range of 999
999 999 LU in this case (999 999 999 LU traversing range / 4096 LU
per encoder revolution = 244 140 encoder revolutions)
Resolution of the
actual position
NOTE
Resolution with
resolver
