
Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23
167
5
Motor control (MCTRL)
5.4
V/f characteristic control (VFCplus)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
How to set the V
min
boost:
1. Operate motor in idle state at approx. 6 % of the rated motor speed.
2. Increase V
min
boost (
) until the following motor current is reached:
Motor in short-time operation up to 0.5 n
rated
• for self-ventilated motors: I
motor
≈
I
rated motor
• for forced ventilated motors: I
motor
≈
I
rated motor
Motor in continuous operation up to 0.5 n
rated
• for self-ventilated motors: I
motor
≈
0.8 I
rated motor
• for forced ventilated motors: I
motor
≈
I
rated motor
5.4.3.3
Optimising the Imax controller
Using the Lenze setting of the current limitation controller, the drive is stable:
Most applications do not require optimisation.
The setting of the current limitation controller must be adapted if
• power control including great moments of inertia is performed.
• Recommendation: Increase of the reset time Ti (
) of the I
max
controller.
• vibrations occur in the V/f control (V encoder) mode during the intervention of the
current limitation controller.
• Recommendation: Increase of the reset time Ti (
) of the I
max
controller.
• overcurrent errors (e.g. OC3) occur due to load impulses or too high acceleration ramps.
• Recommendation: Reduction of the gain Vp (
) and reset time Ti (
I
max
controller.
Note!
V
min
boost is automatically calculated by the motor parameter identification using the
data specified on the motor nameplate so that a no-load current of approx. 0.8 I
rated
motor
results at the slip frequency of the machine.
V/f control (V encoder)
If V/f control (V encoder) is selected, we recommend a decidedly lower V
min
boost:
• In this case, select a V
min
boost which ensures that approx. 50 % of the rated motor
current flows at slip frequency when the motor is idling.
Parameters
Info
Lenze setting
Value Unit
VFC: Vp Imax controller
0.25
VFC: Ti Imax controller
65 ms