Danfoss VLT HVAC Basic Drive FC 101 Design Manual page 31

Introduction to VLT® HVAC B...
2.7.8 Tuning the Drive Closed Loop
Controller
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Once the frequency converter's closed loop controller has
been set up, the performance of the controller should be
tested. In many cases, its performance may be acceptable
using the default values of 20-93 PI Proportional Gain and
20-94 PI Integral Time. However, in some cases it may be
helpful to optimize these parameter values to provide
faster system response while still controlling speed
overshoot.
2.7.9 Manual PI Adjustment
1. Start the motor.
2. Set 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 set-point 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 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 set-point 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%.
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VLT HVAC Basic Drive Design Guide
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MG18C402 - VLT is a registered Danfoss trademark