EC590
Function parameters description
EC590
Function parameters description
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5.5.2 Torque Boost
The torque compensation function compensates for insufficient torque production at low
frequency.
Function Code
Parameter Name
Default
F3-01
Torque boost
Setting Range
Model
dependent
0.0%: No torque boost 0.1% to 30%
F3-02
Cut-off frequency of torque
boost
50.00 Hz
0.00 Hz to max. frequency
F3-01 compensates for insufficient torque production by boosting output voltage of the AC drive.
But very large setting will result in motor overheat and AC drive overcurrent.
●
On starting a heavy load and insufficient torque is experienced, increase the torque boost in
F3-01.
●
Decrease this parameter on light loads to avoid overheating the motor.
F3-02 sets the cutoff frequency. The torque boost function is disengaged when the output fre-
quency exceeds the cutoff point.
5.5.3 Current Limit Control
When output current exceeds the value set in F3-18 during acceleration, constant running or de
-
celeration, current limit is enabled and output frequency starts to drop. Until output current recovers
below the current limit level, output frequency starts to rise to target frequency again.
Figure 5-20 Current limit
Output current
Output frequency
Set frequency
Time
time
Accelerate
process
Constant speed
process
Decelerate
process
150
%
Function Code
Parameter Name
Default
F3-18
Current limit level
Setting Range
Model
dependent
50% to 200%
F3-19
Current limit selection
1
0: Disabled
1: Enabled
F3-20
Current limit gain
20
0 to 100
F3-21
Compensation factor of
speed multiplying current
limit
0
50% to 200%
In high frequency area, motor drive current is small. Bigger motor speed dip is caused by current
limit level compared with below rated frequency. To improve motor running characteristic, you can
lower current limit level above rated frequency.
The current limit function above rated frequency helps to improve acceleration performance in
the applications, such as centrifuge, where high running frequency and several times of field weak-
ening are required, and load inertia is large.
The current limit level above rated frequency = (fs/fn) x k x LimitCur.
●
fs: running frequency
●
fn: rated motor frequency
●
k: compensation factor of speed multiplying current limit level (F3-21)
●
LimitCur: current limit level (F3-18)
Figure5-21 Current limit above rated frequency
rated
frequency
Twice of rated
fruquency
Current limit level
above rated frequency
Frequency
Current
Note
● Current limit level 150% indicates 1.5 times of rated current of the AC drive.
● For high-power motor with carrier frequency below 2 kHz, lower the current
limit level. This is because the overcurrent fast prevention function is enabled in
advance of the current limit function due to increase of pulsating current, which
will result in insufficient torque output.
