Set Voltage Boost - Lenze i950 Commissioning Manual

13.4.5

Set voltage boost

As an alternative for the "Activate voltage vector control (Imin
stant, load independent voltage boost can be specified for low speeds (below the V/f rated
frequency) or for a motor standstill in order to optimise the starting performance.
WARNING!
Insufficient cooling of the motor due to longer operation at standstill.
If the motor is operated at standstill for a longer time - especially in case of smaller motors -
the motor can be destroyed by overtemperature!
▶ Connect the PTC thermistor (single sensor according to DIN 44081 or triple sensor according
to DIN 44082) or thermal contact (normally-closed contact)
ing.
^ 272
▶ Parameterise and activate the
NOTICE
The voltage boost is added to the function
ler).
^ 219
Only set one of the two "boost" functions.
Recommendation: voltage vector control
For magnetising the motor, consider a sufficient time from the controller enable
to the start of the speed ramp function generator. The bigger the motor the lon-
ger the time required for magnetisation. A motor with a power of 90 kW
requires up to 2 seconds.
Depending on the required starting torque, the voltage boost must be set so that the required
motor current will be available after controller enable.
The voltage boost can be calculated by multiplying the stator resistance by the rated mag-
•
netising current:
Spannung im Eckpunkt
Optionally, the voltage boost can be determined empirically by increasing the setting until
•
the rated magnetising current flows.
The voltage boost is added geometrically to the voltage of the characteristic:
•
Parameter
Address Name / setting range / [default setting]
0x2B06 Voltage boost
0.0 ... [0.0] ... 100.0 V
V/f characteristic control for asynchronous motor (VFC open loop)
4Motor overload monitoring
4Activate voltage vector control (Imin control-
Anlaufstrom ~ U
U U
U
Boost
0 0
Frequenz im Eckpunkt
0 0
2
U = U
Configuring the motor control
controller)" function, a con-
4Motor temperature monitor-
(i²*t).
^ 264
= ´
R I
Boost s mN
U U
Spannung im Eckpunkt
U U
Boost Boost
f 0 0
soll
0 0
+ 2
U
Kennlinie Boost
Info
Setting of the voltage boost for the voltage vector control.
Set voltage boost
f
soll
Frequenz im Eckpunkt
221