2.8.10 Tuning the Drive Closed-loop Controller
Once the drive’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 PID Proportional Gain (par. 20-93) and PID Integral Time (par. 20-94). However, in some cases it may be helpful
to optimize these parameter values to provide faster system response while still controlling speed overshoot.
2.8.11 Manual PID Adjustment
1. Start the motor
2. Set par. 20-93 (PID Proportional Gain) to 0.3 and increase it until the feedback signal begins to oscillate. If necessary, start and stop the drive
or make step changes in the setpoint reference to attempt to cause oscillation. Next reduce the PID Proportional Gain until the feedback signal
stabilizes. Then reduce the proportional gain by 40-60%.
3. Set par. 20-94 (PID Integral Time) to 20 sec. and reduce it until the feedback signal begins to oscillate. If necessary, start and stop the drive
or make step changes in the setpoint reference to attempt to cause oscillation. Next, increase the PID Integral Time until the feedback signal
stabilizes. Then increase the Integral Time by 15–50%.
4. Par. 20-95 (PID Differential Time) should only be used for very fast-acting systems. The typical value is 25% of the PID Integral Time (par.
20-94). The differential function should only be used when the setting of the proportional gain and the integral time has been fully optimized.
Make sure that oscillations of the feedback signal are sufficiently dampened by the low-pass filter for the feedback signal (par 6 16, 6 26, 5 54
or 5 59, as required).
VLT
®
AQUA Drive Design Guide 2 Introduction to the VLT AQUA Drive
MG.20.N5.22 - VLT
®
is a registered Danfoss trademark
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