Lenze 8400 motec - Manual (Page 126)

5 Motor control (MCTRL)
5.8 Sensorless vector control (SLVC)
126 Lenze · 8400 motec · Reference manual · DMS 4.1 EN · 08/2013 · TD05
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5.8.5 Remedies for undesired drive behaviour
Drive behaviour Remedy
Deviation between no-load current and magnetising
current or bad speed or torque accuracy.
Adapt the motor magnetising inductance ( C00092 ) for
no-load operation.
• If the no-load current is greater than the magnetising
current ( C00095 ) at 0.5-fold rated motor speed, the
magnetising inductance must be reduced until the
no-load current and the magnetising current have the
same values.
• Otherwise, the magnetising inductance must be
increased.
Tendency of the correction of C00092:
PN: Rated motor power
Insufficient speed constancy at high load: Setpoint and
motor speed are not proportional anymore.
Caution: Overcompensation of the settings mentioned
under " Remedy" may result in unstable behaviour!
Via the slip compensation ( C00021 ), the speed stability
under high loads can be affected:
• If n
act
> n
slip
, reduce the value in C00021
• If n
act
< n
slip
, increase the value in C00021
Unstable control with higher speeds. • Check the setting of the magnetising inductance
( C00092 ) by comparing the current consumption in
no-load operation with the rated magnetising current
( C00095 ).
• Optimise oscillation damping ( C00234 ).
"Short circuit" (OC1) error messages at short acceleration
time ( C00012 ) in proportion to the load (controller
cannot follow the dynamic processes).
Increase the acceleration ( C00012 )/deceleration (
C00013 ) time.
Mechanical resonance at certain speeds. The L_NSet_1 function block masks out those speed
ranges that include resonance.
Speed variations in no-load operation for speeds > 1/3
rated speed.
Minimise speed oscillations with oscillation damping
( C00234 ).
Drive runs unstable. Check set motor data (nameplate data and equivalent
circuit diagram data).
 Motor selection/Motor data ( 82)
Setpoint speed and actual speed differ strongly.
0,37 22 90
C0092
-15 %
+15 %
0
P [kW] N