20-82 PID Start Speed [RPM]
Range:
Function:
Size
related
*
[ 0 -
par. 4-13
RPM]
When the frequency converter is first
started, it initially ramps up to this output
speed in Open Loop Mode, following the
active Ramp Up Time. When the output
speed programmed here is reached, the
frequency converter will automatically
switch to Closed Loop Mode and the PID
Controller will begin to function. This is
useful in applications in which the driven
load must first quickly accelerate to a
minimum speed when it is started.
NOTE
This parameter will only be visible if
is set to
[0] RPM
.
20-83 PID Start Speed [Hz]
Range:
Function:
Size
related
*
[ 0 -
par.
4-14
Hz]
When the frequency converter is first
started, it initially ramps up to this output
frequency in Open Loop Mode, following
the active Ramp Up Time. When the output
frequency programmed here is reached, the
frequency converter will automatically
switch to Closed Loop Mode and the PID
Controller will begin to function. This is
useful in applications in which the driven
load must first quickly accelerate to a
minimum speed when it is started.
NOTE
This parameter will only be visible if
is set to
[1] Hz
.
20-84 On Reference Bandwidth
Range:
Function:
5 %
*
[0 -
200 %]
When the difference between the feedback and
the setpoint reference is less than the value of
this parameter, the frequency converter’s display
will show “Run on Reference”. This status can be
communicated externally by programming the
function of a digital output for
[8] Run on
Reference/No Warning
. In addition, for serial
communications, the On Reference status bit of
the frequency converter’s Status Word will be
high (1).
The
On Reference Bandwidth
is calculated as a
percentage of the setpoint reference.
3.15.7 20-9* PID Controller
This group provides the ability to manually adjust this PID
Controller. By adjusting the PID Controller parameters the
control performance may be improved. See section PID in
the
VLT Refrigeration Drive FC 103 Design Guide
for
guidelines on adjusting the PID Controller parameters.
20-91 PID Anti Windup
Option: Function:
[0]
Off
[0] Off
The integrator will continue to change value
also after output has reached one of the extremes.
This can afterwards cause a delay of change of the
output of the controller.
[1]
*
On
[1] On
The integrator will be locked if the output of
the built in PID controller has reached one of the
extremes (min or max value) and therefore not able to
add further change to the value of the process
parameter controlled. This allows the controller to
respond more quickly when it again can control the
system.
20-93 PID Proportional Gain
Range:
Function:
0.50
*
[0 - 10 ] The proportional gain indicates the number of
times the error between the set point and the
feedback signal is to be applied.
If (Error x Gain) jumps with a value equal to what is set in
20-14 Maximum Reference/Feedb.
the PID controller will try
to change the output speed equal to what is set in
4-13 Motor Speed High Limit [RPM]
but in practice of course limited by this setting.
The proportional band (error causing output to change
from 0-100%) can be calculated by means of the formula
(
1
Proportional Gain
)
× (
Max Reference)
NOTE
Always set the desired for
20-14 Maximum Reference/Feedb.
before setting the values for the PID controller in
parameter group 20-9*.
Parameter Description
VLT
®
Refrigeration Drive Programming Guide
MG16H102 - VLT
®
is a registered Danfoss trademark
119
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