5 Motor control (MCTRL)
5.4 V/f characteristic control (VFCplus)
174
Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23
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5.4.4 Remedies for undesired drive behaviour
Drive behaviour Remedy
Inadequate smooth running at low speeds, especially in
the case of operation with a long motor cable
Automatic motor data identification
( 141)
Problems in case of high starting duty (great mass
inertia)
Adapting the Vmin boost
( 166)
Drive does not follow the speed setpoint. The current controller intervenes in the set field
frequency to limit the controller output current to the
maximum current (C0022, C0023). Therefore:
• Prolong acceleration/deceleration times:
C00012:
Accel. time - main setpoint
C00013
: Decel. time - main setpoint
• Consider a sufficient magnetising time of the motor.
Depending on the motor power, the magnetising
time amounts to 0.1 ... 0.2 s.
• Increase the maximally permissible current:
C00022
: Imax in motor mode
C00023
: Imax in generator mode)
For operation without speed feedback (C00006
= 6):
Insufficient speed constancy at high load (setpoint and
motor speed are not proportional anymore)
•Increase slip compensation (C00021).
Important: Unstable drive due to overcompensation!
• With cyclic load impulses (e. g. centrifugal pump), a
smooth motor characteristic is achieved by smaller
values in C00021
(possibly negative values).
Note: The slip compensation is only active for operation
without speed feedback.
"Clamp operation active" error message (oC11):
Inverter cannot follow dynamic processes, i.e. too short
acceleration/deceleration times in terms of load ratios.
• Increase the gain of the I
max
controller (C00073/1)
• Reduce the reset time of the I
max
controller
(C00074/1
)
• Prolong the acceleration time (C00012
)
• Prolong the deceleration time (C00013
)
Motor stalling in the field weakening range
(adaptation especially required for small machines)
• Reduce the override point of field weakening
(C00080
)
• If motor power < inverter power:
Set C00022
to I
max
= 2 I
rated motor
• Reduce dynamic performance of setpoint generation
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