Danfoss VLT Compressor Drive CDS 803 - Tuning the Drive Closed-Loop Controller; Manual PI Adjustment

Parameter Option Default Function
Parameter 8-01 Control Site [0] Digital and ctrl.word
[1] Digital only
[2] Controlword only
[0] Digital and
ctrl.word
Select if digital, bus, or a combination of both
should control the frequency converter.
Parameter 8-30 Protocol [0] FC
[2] Modbus RTU
[0] FC Select the protocol for the integrated RS485
port.
Parameter 8-32 Baud Rate [0] 2400 Baud
[1] 4800 Baud
[2] 9600 Baud
[3] 19200 Baud
[4] 38400 Baud
[5] 57600 Baud
[6] 76800 Baud
[7] 115200 Baud
[2] 9600 Baud Select the baud rate for the RS485 port.
Parameter 20-00 Feedback 1 Source [0] No function
[1] Analog Input 53
[2] Analog Input 54
[3] Pulse input 29
[100] Bus Feedback 1
[101] Bus Feedback 2
[0] No function Select which input is used as the source of
the feedback signal.
Parameter 20-01 Feedback 1
Conversion
[0] Linear
[1] Square root
[0] Linear Select how the feedback should be calculated
Table 2.3 Closed-loop Applications Set-up
2.6.7 Tuning the Drive Closed-loop
Controller
Once the frequency converter's closed-loop controller has
been set up, test the performance of the controller. Often,
its performance may be acceptable using the default
values of parameter 20-93 PI Proportional Gain and
parameter 20-94 PI Integral Time. However, sometimes it
may be helpful to optimize these parameter values to
provide faster system response while still controlling speed
overshoot.
2.6.8 Manual PI Adjustment
1. Start the compressor.
2. Set parameter 20-93 PI Proportional Gain to 0.3
and increase it until the feedback signal begins to
oscillate. If necessary, start and stop the
frequency converter or make step changes in the
setpoint reference to attempt to cause oscillation.
Next, reduce the PI proportional gain until the
feedback signal stabilizes. Then reduce the
proportional gain by 40–60%.
3. Set parameter 20-94 PI Integral Time to 20 s and
reduce it until the feedback signal begins to
oscillate. If necessary, start and stop the
frequency converter or make step changes in the
setpoint reference to attempt to cause oscillation.
Next, increase the PI integral time until the
feedback signal stabilizes. Then increase of the
integral time by 15–50%.
Product Overview
VLT
®
Compressor Drive CDS 803
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