Lenze EVF9383 User Manual
Page 171
Operating mode
V/f characteristic control
6.8
6.8.1
l
6.8−7
EDSVF9383V EN 7.1−04/2012
In general the V/f characteristic control can be operated without any further
measures. The V/f characteristic control must only be optimised in case of
the following drive behaviour:
Drive behaviour
Remedy
Does not rotate concentrically at low
speeds, especially when operating
with long motor cables
Executing motor identification
Problems in case of high starting
duty (high mass inertia), in extreme
cases, the error message OC1 occurs
Adjusting the voltage increase (C0016).
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Set C0016 so that with an enabled controller and
5 ... 10 % of the rated speed an approx.
0.8−fold ... single rated motor current flows
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^ 6.8−6
The set voltage increase (C0016)
does not result in the desired current
flow (controller has problems at high
starting duty, error message OC1
during acceleration).
Adapting the voltage increase with boost correction
(
¶ 6.11−5)
Drive does not follow the speed
setpoint.
Reason: The current controller
intervenes in the rated field
frequency to limit the controller
output current to the maximum
current (C0022, C0023)
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Increasing acceleration / deceleration time
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Consider sufficient magnetising time of the motor.
the magnetising time amounts to 0.1 ... 2 s
depending on the motor power
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Increase permissible maximum current (C0022,
C0023)
For operation without speed
feedback (C0025 = 1):
Lack of speed stability at high load
(setpoint and motor speed are not
proportional anymore)
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Increase slip compensation (C0021). Important:
unstable drive due to overcompensation!
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In case of cyclic load impulses (e.g. centrifugal pump)
a smoother motor characteristic can be achieved by
smaller values in C0021 (maybe negative values)
Note: The slip compensation is only active for operation
without speed feedback.
Error messages OC1 or OC3 with
short acceleration times (C0012)
compared with the load (controller
cannot follow the dynamic
processes)
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Increase gain of the I
max
controller (C0075)
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Reduce integral−action time of the I
max
controller
(C0076)
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Increase acceleration time (C0012)
Mechanical resonances at certain
speeds
The function block NLIM1 serves to suppress those
speed ranges in which resonances occur (see chapter
"Function library").
Speed oscillations in no−load
operation at speeds >
1
/
3
rated
speed
The oscillation damping minimises speed oscillations
(see "Optimising operational performance" in chapter
"Commissioning")
Optimising V/f characteristic
control