User`s manual

156 • Vacon apfiff09 marine
Tel. +358
6
Slip compensation in open loop control
The drive uses motor torque and motor nominal rpm to compensate slip. If the motor nominal rpm
is 1440 -> the nominal slip is 60 rpm. And when the motor torque is 50 % the slip is 30 rpm. To keep
the reference speed the drive must increase the output frequency by 1 Hz.
T
N
100 %
T
N
50 %
Freq. Out 51 Hz
Slip
Freq. Ref 50 Hz
”Shaft
Freq”
Closed Loop control
Closed loop control controls the motor using the exact information of the motor speed from the
encoder. Control mode selections 3 and 4 are closed loop control modes. Using these modes without
encoder board (and encoder) will result in encoder fault.