Danfoss VLT AutomationDrive FC 360 Programming Manual

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Danfoss VLT AutomationDrive FC 360 Programming Manual Manual pdf 67 page image

4.8 Parameters: 7-** Controllers4.8.1 7-0* Speed PID Ctrl.7-00 Speed PID Feedback SourceOption: Function:NOTICEThis parameter cannot bechanged while the motor isrunning.Select feedback source for Speed CLControl.[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] * None7-02 Speed PID Proportional GainRange: Function:0.015* [0 -1 ]Enter the speed controller proportional gain. Theproportional gain amplifies the error (i.e. thedeviation between the feedback signal and theset-point). This parameter is used with1-00 Configuration Mode [0] Speed open loop and[1] Speed closed loop control. Quick control isobtained at high amplification. However, if theamplification is too large, the process maybecome unstable.7-03 Speed PID Integral TimeRange: Function:8ms*[2 -20000ms]Enter the speed controller integral time, whichdetermines the time the internal PID controltakes to correct errors. The greater the error,the more quickly the gain increases. Theintegral time causes a delay of the signal andtherefore a dampening effect, and can be usedto eliminate steady state speed error. Obtainquick control through a short integral time,though if the integral time is too short, theprocess becomes unstable. An excessively longintegral time disables the integral action,leading to major deviations from the requiredreference, since the process regulator takes toolong to regulate errors. This parameter is usedwith [0] Speed open loop and [1] Speed closedloop control, set in 1-00 Configuration Mode.7-04 Speed PID Differentiation TimeRange: Function:30ms*[0 -200 ms]Enter the speed controller differentiation time.The differentiator does not react to constanterror. It provides gain proportional to the rateof change of the speed feedback. The quickerthe error changes, the stronger the gain fromthe differentiator. The gain is proportional withthe speed at which errors change. Setting thisparameter to zero disables the differentiator.This parameter is used withparameter 1-00 Configuration Mode [1] Speedclosed loop control.7-05 Speed PID Diff. Gain LimitRange: Function:5* [1 -20 ]Set a limit for the gain provided by the differen-tiator. Since the differential gain increases at higherfrequencies, limiting the gain may be useful. Forexample, set up a pure D-link at low frequenciesand a constant D-link at higher frequencies. Thisparameter is used with parameter 1-00 ConfigurationMode [1] Speed closed loop control.7-06 Speed PID Lowpass Filter TimeRange: Function:10ms*[1 -100ms]NOTICESevere filtering can be detrimental todynamic performance.This parameter is used with 1-00 Configu-ration Mode [1] Speed closed loop.Set a time constant for the speed control low-passfilter. The low-pass filter improves steady-stateperformance and dampens oscillations on thefeedback signal. This is an advantage if there is agreat amount of noise in the system, seeIllustration 4.19. For example, if a time constant (τ)of 100 ms is programmed, the cut-off frequencyfor the low-pass filter is 1/0.1= 10 RAD/s.,corresponding to (10/2 x π) = 1.6 Hz. The PIDregulator only regulates a feedback signal thatvaries by a frequency of less than 1.6 Hz. If thefeedback signal varies by a higher frequency than1.6 Hz, the PID regulator does not react.Practical settings of parameter 7-06 Speed PIDLowpass Filter Time taken from the number ofpulses per revolutions from encoder:Encoder PPR 7-06 Speed PIDLowpass Filter Time512 10 ms1024 5 ms2048 2 ms4096 1 msParameter Descriptions Programming GuideMG06C402 Danfoss A/S © Rev. 2014-03-31 All rights reserved. 654 4