Position Encoder At Material Path - Lenze 9300 System Manual

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7.5.2.1
L

Position encoder at material path

Purpose
The gearbox backlash and the slip between drive, machine, and material should be eliminated to
increase the accuracy of the calculation of an act. position value.
Function
•
The feedback is ensured by a separate position encoder (C0490) at the material web.
•
The speed is fed back through an encoder mounted to the motor shaft (C0495).
Tip!
For defining the dimension of a unit (e.g. mm, cm), machine parameters are entered as if the position
encoder was mounted to the motor shaft.
•
There is a ratio between the position encoder and the motor. This ratio is adjusted via the
"encoder/gearbox factor" (C1207/1, C1207/2). Counter and denominator are entered
according to the speed ratio between motor and position encoder.
•
The counting direction of the actual position value (GDC monitor, C1220/3) must increase with
CC rotation of the motor.
If this is not the case, the counting direction of the position encoder can be inverted as follows:
1. Changing the encoder track
2. Changing the polarity of the actual position value (C1208)
Stop!
An opposing setting of the counting directions of the position setpoint and the actual position value
leads to a positive feedback in the control loop with the consequence that the drive may race.
•
≤
For software version
– Inverting the counting direction via the actual value polarity (C1208) is not considered while
executing the QSP function.This could lead to a positive feedback in the position control
loop when the QSP or FAIL-QSP function is activated. The drive could accelerate to its
speed limit n in an uncontrolled way ("race")!
max
– Therefore the positioning controller must be switched off during the update of the QSP
function (MCTRL-QSP-OUT = HIGH). In the case of QSP it is not enough to only switch the
input MCTRL-PHI-ON = LOW. The analog input MCTRL-P-ADAPT = 0% must be switched
e.g. by means of the function block ASW via MCTRL-QSP-OUT.
•
For software version > V2.1:
With QSP only the motor encoder is automatically evaluated to stop the motor.
Stop!
Increasing the ratio between the position encoder and the motor shaft reduces the resolution of the
position information. This can have a negative effect on the stability of the control loop!
C1207∕1
=
C1207∕2
V2.1:
EDSVS9332P-D21 EN 3.0
Function library
n
Motor
n
Encoder
7-33