4.8 Parameters: 7-** Controllers
4.8.1 7-0* Speed PID Ctrl.
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
[2]
MCB 102
[3]
MCB 103
[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 amplifies the error (that is the
deviation between the feedback signal and the
setpoint). This parameter is used with
parameter 1-00 Configuration Mode
[0] Speed open
loop
and
[1] Speed closed loop
control. Quick
control is obtained at high amplification. However,
if the amplification 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 effect, 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 Configuration
Mode
.
7-04 Speed PID Differentiation Time
Range:
Function:
30
ms
*
[0 -
200 ms]
Enter the speed controller differentiation time.
The differentiator does not react to constant
error. It provides gain proportional to the rate
of change of the speed feedback. The quicker
the error changes, the stronger the gain from
the differentiator. The gain is proportional with
the speed at which errors change. Setting this
parameter to zero disables the differentiator.
This parameter is used with
parameter 1-00 Configuration Mode
[1] Speed
closed loop
control.
7-05 Speed PID Diff. Gain Limit
Range:
Function:
5
*
[1 -
20 ]
Set a limit for the gain provided by the differen-
tiator. Since the differential 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
[1] Speed closed loop
control.
7-06 Speed PID Lowpass Filter Time
Range:
Function:
10
ms
*
[1 -
100
ms]
NOTICE
Severe filtering can be detrimental to
dynamic performance.
This parameter is used with
parameter 1-00 Configuration Mode
[1] Speed
closed loop
.
Set a time constant for the speed control low-pass
filter. The low-pass filter 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
. For example, if a time constant (τ)
of 100 ms is programmed, the cutoff frequency for
the low-pass filter 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
taken from the number of
pulses per revolutions from encoder:
Parameter Descriptions
VLT
®
AutomationDrive FC 360
68
Danfoss A/S © 7/2015 All rights reserved.
MG06C602
4
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