Danfoss VLT Midi Drive FC 280 Programming Guide

4.8 Parameters: 7-** Controllers
7-00 Speed PID Feedback Source
Option: Function:
NOTICE
This parameter cannot be
changed while the motor is
running.
Select feedback source for speed CL
control.
[1] 24V encoder
[6] Analog Input 53
[7] Analog Input 54
[8] Frequency input 29
[9] Frequency input 33
[20] * None
7-02 Speed PID Proportional Gain
Range: Function:
0.015* [0 -
1 ]
Enter the speed controller proportional gain. The
proportional gain amplies the error (that is the
deviation between the feedback signal and the
setpoint). This parameter is used with
parameter 1-00 Conguration Mode [0] Speed open
loop and [1] Speed closed loop control. Quick
control is obtained at high amplication. However,
if the amplication is too high, the process may
become unstable.
7-03 Speed PID Integral Time
Range: Function:
8
ms*
[2 -
20000
ms]
Enter the speed controller integral time, which
determines the time the internal PID control
takes to correct errors. The greater the error,
the more quickly the gain increases. The
integral time causes a delay of the signal and
therefore a dampening eect, and can be used
to eliminate steady-state speed error. Obtain
quick control through a short integral time,
though if the integral time is too short, the
process becomes unstable. An excessively long
integral time disables the integral action,
leading to major deviations from the required
reference, since the process regulator takes too
long to regulate errors. This parameter is used
with [0] Speed open loop, and [1] Speed closed
loop control set in parameter 1-00 Conguration
Mode.
7-04 Speed PID Dierentiation Time
Range: Function:
30
ms*
[0 -
200 ms]
Enter the speed controller dierentiation time.
The dierentiator does not react to constant
error. It provides gain proportional to the rate
7-04 Speed PID Dierentiation Time
Range: Function:
of change of the speed feedback. The quicker
the error changes, the stronger the gain from
the dierentiator. The gain is proportional with
the speed at which errors change. Setting this
parameter to 0 disables the dierentiator. This
parameter is used with parameter 1-00 Congu-
ration Mode [1] Speed closed loop control.
7-05 Speed PID Di. Gain Limit
Range: Function:
5* [1 -
20 ]
Set a limit for the gain provided by the dieren-
tiator. Since the dierential gain increases at higher
frequencies, limiting the gain may be useful. For
example, set up a pure D-link at low frequencies
and a constant D-link at higher frequencies. This
parameter is used with parameter 1-00 Conguration
Mode [1] Speed closed loop control.
7-06 Speed PID Lowpass Filter Time
Range: Function:
10
ms*
[1 -
100
ms]
NOTICE
Severe ltering can be detrimental to
dynamic performance.
This parameter is used with
parameter 1-00 Conguration Mode [1] Speed
closed loop.
Set a time constant for the speed control low-pass
lter. The low-pass lter improves steady-state
performance and dampens oscillations on the
feedback signal. This parameter is useful if there is
a great amount of noise in the system, see
Illustration 4.15. For example, if a time constant (τ)
of 100 ms is programmed, the cuto frequency for
the low-pass lter is 1/0.1=10 RAD/s.,
corresponding to (10/2 x π)=1.6 Hz. The PID
regulator only regulates a feedback signal that
varies by a frequency of less than 1.6 Hz. If the
feedback signal varies by a higher frequency than
1.6 Hz, the PID regulator does not react.
Practical settings of parameter 7-06 Speed PID
Lowpass Filter Time taken from the number of
pulses per revolutions from encoder:
Encoder PPR Parameter 7-06 Speed
PID Lowpass Filter Time
512 10 ms
1024 5 ms
2048 2 ms
4096 1 ms
Parameter Descriptions
VLT
®
Midi Drive FC 280
66 Danfoss A/S © 12/2015 All rights reserved. MG07C102
44

Danfoss VLT Midi Drive FC 280 Specifications

General

Brand	Danfoss
Model	VLT Midi Drive FC 280
Category	DC Drives
Language	English