NFO
Drives
AB
2021
201013
‐
2
Operating
and
Installation
Manual
28
Default setting of
Kp-speed
is 2.00 and
Ti-speed
is 1.00 sec, which works during most operating conditions. Loads
with high inertial torque, or motors with multiple poles may need to have
Kp-speed
and / or
Ti-speed
adjusted. The
following guidelines may be helpful when adjusting:
First, set the regulator so it works more or less purely as a P-regulator. This is done by setting the maximum time
(
Ti-speed
) for the integrator amplification.
Start motor at low P amplification (
Kp-speed
). Increase the P amplification carefully until its control becomes
unstable and/or shows a tendency to over-react to control signals (indicated by a rotor speed overrun after a
setspeed change). Then reduce P amplification until the control is stable again.
At maximum integration time, it will take longer than necessary for the motor to achieve the specified speed
(setspeed). Reduce the integration time (
Ti-speed
) carefully, which is indicated by the fact that the speed control
sets itself faster at the correct speed. If the integration time selected is too short, this will show up as an unstable
response to speed changes with overruns in speed regulation. Select the integration time that gives the fastest
response but without speed oscillations.
Kp -sp d
e
s
Ti-sp d
1
Sp eed
setp oint
Power
elec tronic s
a nd
m otor
m od el
Estim a ted spee d a c tua l value
-
+
+
Integ ra tor
c om p onent
Fig. 11. Speed regulator
If you have any doubts or problems, please contact NFO Drives AB.
5.8.8 Frequency sleep setting
This function is to minimize power consumption when running motor at low speed. When both setpoint frequency
and actual frequency are within the interval 0 –
Fsleep
the motor is released. The motor is started again when the
setpoint frequency is outside the interval 0 – (
Frq Sleep
+ 0.5Hz). This setting applies to all modes (
Freque
and
Speed
).
The default value of 0.0Hz disables this function.
Example: Fan application regulated by a temperature setpoint.
Frq Sleep
= 5.0Hz
The motor runs at 30Hz. When a drop in temperature below actual setpoint, the inverter’s setpoint updates to
4.0Hz. The inverter will now slow the motor down according to retardation ramp until 5Hz where it will release the
motor. The inverter will not start the motor again until setpoint is set above 5.5 Hz.
5.8.9 Frequency
bypass
The function is used to avoid operating inverter within a selected frequency range (frequency bypass). Two
parameters are used to set the frequency range:
Bypass-fr
sets the frequency's mid-frequency and
Bypass-BW
sets the bandwidth. This function is disabled when both
Bypass-fr
and
Bypass-BW
are set to 0.0 Hz.
If the inverter is accelerating (or decelerating) towards a setpoint value and the actual rotor speed enters the
bypass window, the inverter will use fastest possible acceleration (or deceleration) until the rotor speed is outside
the bypass window.
3006469-2022-04
