Lenze 8615E - Manual (Page 75)

73
4 Closed-loop speed control
For a number of applications, the accuracy which can be obtained
with open-loop speed control is often not sufficient. To avoid a
speed reduction which occurs when an asynchronous motor is
loaded, you can select a configuration with a PI controller. The
appropriate configuration depends on the way of set-value input
and the actual value input you want to use.
Closed-loop speed control:
Code Parameter Meaning Acceptance
Set-value 1 Set-value 2 Actual value
C005 -11- Terminals 7/8 (bipolar) or
LECOM (bipolar) or keypad
(bipolar) Terminals 1/2
(bipolar) Terminals 3/4
analog feedback [SH + PRG]
-13- Terminals 7/8 (bipolar) or
LECOM (bipolar) or keypad
(bipolar) Terminals 1/2
(bipolar) Input X5
Digital frequency (2-
track)
-14- * Input X8
Digital frequency (2-track) Terminals 1/2
(bipolar) Input X5
Digital frequency (2-
track)
-15-* Input X5
Digital frequency (2-track) Terminals 1/2
(bipolar) Input X8
Pulse encoder (2-
track)
* According to the configuration selected, set-value 1 or the feedback can be
output via the digital frequency output X9.
4.1 Analog feedback
If you use a DC tachogenerator, you should know the maximum
tacho voltage to be expected. You can calculate this tacho voltage
from the ratings of the tacho and the maximum drive speed.
Connect the tacho to input X1/terminals 3, 4, and select the position
of the switch S1, which is required for the maximum tacho voltage
(see page 29).
4.2 Digital feedback
If you use an incremental encoder for feedback, first select the input
for this encoder under code C025. To enter the encoder constant,
two steps are necessary in general:
•
Select the closest value under C026.
•
Compensate the difference under C027.
Encoder constant =
Pulses per revolution of the encode
Pole pair number of the motor
Adjustment (C027) =
Constant (C026)
Encoder constant
Code Parameter Meaning Acceptance
C025 -10-
-11- Incremental encoder input X5
Incremental encoder input X8 SH + PRG
C026 -1-
-2-
-3-
-4- 512 Increments/revolution
1024 Increments/revolution
2048 Increments/revolution
4096 Increments/revolution SH + PRG
C027 1.000
-5.000...+5.000 Signal gain ON-LINE