Lenze 8400 TopLine - Manual (Page 184)

5 Motor control (MCTRL)
5.5 V/f characteristic control - energy-saving (VFCplusEco)
184
Lenze · 8400 TopLine · Reference manual · DMS 6.0 EN · 06/2014 · TD05/TD14
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5.5.5 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)
Reduce the influence of the Eco function by increasing
the minimum voltage V/f ( C00977 ) if necessary.
Problems in case of high starting duty (great mass
inertia)
1.Set motor control VFCplus with linear characteristic
( C00006 = 6).
2. Adapting the Vmin boost . ( 166)
3.Again set motor control VFCplusEco ( C00006 = 11).
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
• Make adaptations for the Eco function:
• Improving the behaviour at high dynamic load
changes . ( 182)
• Adapting the slope limitation for lowering the Eco
function . ( 183)
• Optimising the cos/phi controller . ( 183)
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):
Controller 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 )
• Reduce the reset time of the I
max
controller ( C00074 )
• Prolong the acceleration time ( C00012 )
• Prolong the deceleration time ( C00013 )
• Make adaptations for the Eco function:
• Improving the behaviour at high dynamic load
changes . ( 182)
• Adapting the slope limitation for lowering the Eco
function . ( 183)
Motor stalling in the field weakening range
(adaptation especially required for small machines)
• If motor power < inverter power:
Set C00022 to I
max
= 2 I
rated motor
• Reduce dynamic performance of setpoint generation
• Make adaptations for the Eco function:
• Improving the behaviour at high dynamic load
changes . ( 182)
• Adapting the slope limitation for lowering the Eco
function . ( 183)
Speed variations in no-load operation for speeds > 1/3
rated speed.
Minimise speed oscillations with oscillation damping
( C00234 ).