ABB ACS850 series, Manual

Page: 165 / 370

Parameters 165
19
19 Speed calculation Speed feedback, speed window, etc. settings.
19.01 Speed scaling Defines the terminal speed value used in acceleration and the
initial speed value used in deceleration (see parameter group
22 Speed ref ramp ). Also defines the rpm value that
corresponds to 20000 for fieldbus communication with ABB
Drives communication profile.
0 … 30000 rpm Acceleration/deceleration terminal/initial speed. 1 = 1 rpm
19.02 Speed fb sel Selects the speed feedback value used in control.
Estimated A calculated speed estimate is used. 0
Enc1 speed Actual speed measured with encoder 1. The encoder is
selected by parameter
90.01 Encoder 1 sel .
1
Enc2 speed Actual speed measured with encoder 2. The encoder is
selected by parameter
90.02 Encoder 2 sel .
2
19.03 MotorSpeed filt Defines the time constant of the actual speed filter, i.e. time
within the actual speed has reached 63% of the nominal
speed (filtered speed =
01.01 Motor speed rpm ).
If the used speed reference remains constant, the possible
interferences in the speed measurement can be filtered with
the actual speed filter. Reducing the ripple with filter may
cause speed controller tuning problems. A long filter time
constant and fast acceleration time contradict one another. A
very long filter time results in unstable control.
If there are substantial interferences in the speed
measurement, the filter time constant should be proportional
to the total inertia of the load and motor, in this case 10…30%
of the mechanical time constant
t
mech
= ( n
nom
/ T
nom
) × J
tot
× 2
π
/ 60, where
J
tot
= total inertia of the load and motor (the gear ratio
between the load and motor must be taken into account)
n
nom
= motor nominal speed
T
nom
= motor nominal torque
See also parameter 23.07 Speed err Ftime .
0.000 … 10000.000
ms Time constant of the actual speed filter. 1000 = 1 ms
19.06 Zero speed limit Defines the zero speed limit. The motor is stopped along
a speed ramp until the defined zero speed limit is reached.
After the limit, the motor coasts to stop.
0.00 … 30000.00
rpm Zero speed limit. 100 = 1 rpm
No. Name/Value Description FbEq