Program features 45
The function is also available for scalar motor control with a frequency reference. The
input of the function is shown by 28.96 Frequency ref act 7.
Example
A fan has vibrations in the range of 540…690 rpm and 1380…1560 rpm. To make the
drive avoid these speed ranges,
• set the critical speeds function by turning on bit 0 of parameter 22.51 Critical
speed function, and
• set the critical speed ranges as in the figure below.
Settings
• Critical speeds: parameters 22.51…22.57 (page 223)
• Critical frequencies: parameters 28.51…28.57 (page 247).
Speed controller autotune
The speed controller of the drive can be automatically adjusted using the autotune
function. Autotuning is based on an estimation of the mechanical time constant
(inertia) of the motor and machine.
The autotune routine will run the motor through a series of acceleration/deceleration
cycles, the number of which can be adjusted by parameter 25.40. Higher values will
produce more accurate results, especially if the difference between initial and
maximum speeds is small.
The maximum torque reference used during autotuning will be the initial torque (ie.
torque when the routine is activated) plus 25.38, unless limited by the maximum
torque limit (parameter group 30 Limits) or the nominal motor torque (99 Motor data).
The calculated maximum speed during the routine is the initial speed (ie. speed when
the routine is activated) + 25.39, unless limited by parameter 30.12 or 99.09.
540
690
1380
1560
1Par. 22.52 = 540 rpm
2Par. 22.53 = 690 rpm
3Par. 22.54 = 1380 rpm
4Par. 22.55 = 1560 rpm
1234
22.01 Speed ref unlimited (rpm)
(output of function)
22.87 Speed reference act 7 (rpm)
(input of function)
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