Setting parameters
10/05 AWB8230-1541GB
68
Output voltage and voltage boost
If the mass inertia moment or static friction of the connected load
is high, the output voltage must be increased (boosted) beyond
the normal U/f component at low output frequencies. This
compensates for the voltage drop in the motor windings and can
be up to half of the motor’s nominal voltage. The voltage boost is
defined as a percentage value with parameters PNU A042 and
A043.
PNU A041 lets you select between a manual boost characteristic
(PNU A041 = 00) and automatic voltage boost (PNU A041 = 01.
Automatic voltage boost is added to the U/f characteristic value
depending on the current load (determined by current
measurement).
h
Operation at low speeds over a longer period can cause
overheating of the motor. If the boost value is too high,
the resulting higher current may cause a fault signal.
Figure 71: Voltage boost characteristics
Parameter settings for manual voltage boost:
A42 = 20 % of the output voltage
A43 = 10 % (= 5 Hz)
A44 = 00 (constant torque characteristic)
A45 = 100 % (output voltage = mains voltage)
[%]
U
f
[Hz]
0
5.0
25.0
50.0
PNU A042 = 20
PNU A043 = 10 %
100
PNU Name RUN b031
= 10
Value Function DS
A041 Voltage boost
characteristics
j j 00 Manual voltage boost 00
A241 01 Automatic boost
A042 Boost, manual
voltage boost
j j 0 – 20 % Setting the voltage increase with manual boost. 5.0
A242
A043 Boost,
transition
frequency for
maximum
voltage boost
j j 0 – 50 % Setting the frequency with the highest voltage boost as a percentage of
the base frequency (PNU A003).
3.0
A243
A044 U/f
characteristic
– – 00 Constant torque curve 00
01 Reduced torque curve
A045 U/f
characteristic,
output voltage
– – 20 – 100 % 100
If the rated motor voltage is lower than the mains voltage, enter the
mains voltage in PNU A082 (a page 67) and reduce the output
voltage in PNU A045 to the rated motor voltage.
Example: At 440 V mains voltage and 400 V rated motor voltage enter:
PNU 082 = 440 V, PNU A045 = 91 % (= 400/440 x 100 %).
0
100
20
[%]
U
f
[Hz]
A045
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