Lenze EVS9332xP - Manual (Page 56)

Function library
Positioning control
3.4.2 Machine parameters
3−28
l
EDSVS9332P−EXT DE 2.0
3.4.2.1 Position encoder at material path
Purpose
The gearbox backlash and, if applicable, the slip between the drive, machine, and material path
should be eliminated to increase the accuracy of the calculation of an act. position value.
Function
l The position feedback is ensured by a separate position encoder (C0490) at the material path.
l 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.
l There is a ratio between the position encoder and the motor. This ratio is adjusted via the
"encoder/gearbox factor" (C1207/1, C1207/2). Nominator and denominator are entered
according to the speed ratio between the motor and position encoder.
C1207
ń1
C1207
ń2
+
n
motor
n
encoder
l The counting direction of the actual position value (GDC monitor, C1220/3) must increase with
clockwise rotation of the motor.
Condition: C1206 = 0 (position setpoint not inverted).
If this is not the case, the counting direction of the position encoder can be inverted as follows:
1. Exchanging the encoder tracks
2. Exchanging the polarity of the actual position (C1208)
Stop!
An opposing setting of the counting directions of the position setpoint and the actual position leads
to a positive feedback in the control loop with the consequence that the drive may overspeed.
l For software version
£ V2.1:
– 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
max
in an uncontrolled way (overspeed)!
– Therefore the position 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.
l For software version > V2.1:
With QSP only the motor encoder is evaluated automatically to stop the motor.