User`s manual

apfiff09 marine vacon • 159
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7.8.1 U/f Settings
U/f settings are mainly used in open loop control modes with the exception of the Field weakening
point voltage that is also used in closed loop control mode as a limit for voltage. U/f settings are
used to control the voltage level that are applied to the motor at different frequencies and different
load situations.
U
N
Linear
Programmable
Zero point voltage
Mid point
frequency
Mid point voltage
F
N
FWP
FWP Voltage
Torque Boost
Squared
What changes are required to start with load from 0 Hz?
 First set the motor nominal values (Parameter group 2.1).
Option 1: Automatic functions
Step 1: Make identification with rotating motor
Step 2 (If needed): Activate speed control or U/f optimization (Torque boost).
Step 3 (If needed): Activate both speed control and U/f optimization.
Option 2: Manual tuning
Step 1:
Run the motor using 2/3 of motor nominal frequency as the frequency reference. Read
the motor current in the monitoring menu or use NCDrive for monitoring. This current
shall be set as the motor magnetization current.
Change the U/f curve ratio selection to programmable (= 2).
Run the motor with zero frequency reference and increase the motor zero point voltage
until the motor current is approximately same as the motor magnetising current. (If the
motor is in a low frequency area for only short periods, it is possible to use up to 65 % of
the motor nominal current).