User guide

5 Motor control (MCTRL)
5.4 V/f characteristic control (VFCplus)
84
Lenze · 8400 BaseLine C · Reference manual · DMS 1.6 EN · 01/2014 · TD05
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
5.4.3.2 Adapting the Vmin boost
The V
min
boost (C016) of the motor voltage serves to select a load independent magnetising current
which is required for asynchronous motors. The torque behaviour of the motor can be optimised by
adapting the setting in C016
.
The general linear and quadratic V/f characteristics are shown in the illustrations below. The illust-
rations show the impacts of the parameters used to adapt the characteristic shape.
[5-3] Representation of the linear V/f characteristic (on the left) and quadratic V/f characteristic (on the right)
 To set the V
min
boost, proceed as follows:
1. Operate motor in idle state at approx. 6 % of the rated motor speed.
2. Increase V
min
boost (C016) until the following motor current is reached:
Motor in short-time operation up to 0.5 n
N
• for self-ventilated motors: I
Motor
≈ I
N Motor
• for forced ventilated motors: I
Motor
≈ I
N Motor
Motor in continuous operation up to 0.5 n
N
• for self-ventilated motors: I
Motor
≈ 0.8 I
N Motor
• for forced ventilated motors: I
Motor
≈ I
N Motor
 Note!
The V
min
boost has an effect on output frequencies below the V/f base frequency (C015).
C00015
C00016
C00015
2
C00016
2
V[V]
out
f[Hz]
V
(100 %)
rmot
1/N/PE AC 264 V
3/PE AC 264 V
3/PE AC 550 V
1/N/PE AC 180 V
3/PE AC 100 V
3/PE AC 320 V
C00015
C00016
V[V]
out
f[Hz]
V
(100 %)
rmot
1/N/PE AC 264 V
3/PE AC 264 V
3/PE AC 550 V
1/N/PE AC 180 V
3/PE AC 100 V
3/PE AC 320 V
 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.