Lenze 9400 - Manual (Page 183)

Lenze · Servo-Inverter 9400 HighLine · Reference manual · DMS 10.0 EN · 11/2013 · TD05/06
183
5 Motor interface
5.6 V/f control (VFCplus)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
5.6.1.2 Setting the voltage boost
C00960 and the MI_dnBoostSet_n input of the motor interface serve to define a constant, load
independent voltage boost at low speeds (below the V/f rated frequency) or at motor standstill to
optimise the starting performance.
Depending on the required starting torque, the voltage boost must be set so that the required
motor current will be available after controller enable (starting current ~ V
min
).

Tip!
The required voltage can be calculated by multiplying the stator resistance by the rated
magnetising current:
Optionally, the voltage can be determined empirically by increasing the value for the
voltage boost until the rated magnetising current flows.
• Via the input MI_dnBoostSet_n the voltage has to be selected in [%] relating to the rated motor
voltage ( C00090 ).
• In C00960 , however, the voltage must be set directly in [V].
• Only positive voltage values can be selected, negative values are limited to 0 V.
• Both selections are added:
• The resulting voltage V
Boost
is added geometrically to the characteristic voltage:

Stop!
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 thermal contact (NC contact), PTC, or KTY of the motor and activate the
motor temperature monitoring of the controller.
• Operate self-ventilated motors with a blower, if required.

Note!
When device types > BF7 are used, the voltage boost only functions in a restricted way
due to the hardware properties!
U
min
R
S
I
mN
⋅ =
U
Boost
MI_dnBoostSet_n C00090
100 %
-------------------- C00960 + ⋅ =
U U
Characteristic
2
U
Boost
2
+ =