Danfoss VLT AutomationDrive FC 300 Design Manual page 36

FC 300 Design Guide
Introduction to FC 300
The following tuning guidelines are relevant when using one of the Flux motor control principles in
applications where the load is mainly inertial (with a low amount of friction).
The value of par. 7-02 Speed PID Proportional Gain is dependent on the combined inertia of the motor
and load, and the selected bandwidth can be calculated using the following formula:
Note: Par. 1-20 is the motor power in [kW] (i.e. enter '4' kW instead of '4000' W in the formula). A practical
value for the Bandwidth is 20 rad/s. Check the result of the par. 7-02 calculation against the following
formula (not required if you are using a high resolution feedback such as a SinCos or Resolver feedback):
A good start value for par. 7-06 Speed PID Lowpass Filter Time is 5 ms (lower encoder resolution calls for a
higher filter value). Typically a MaxTorqueRipple of 3 % is acceptable. For incremental encoders, the Encoder
Resolution is found in either par. 5-70 (24V HTL on standard drive) or par. 17-11 (5V TTL on MCB102 Option).
Generally the practical maximum limit of par. 7-02 is determined by the encoder resolution and the feedback
filter time but other factors in the application might limit par. 7-02 Speed PIDProportional Gain to a lower value.
To minimize overshoot, par. 7-03 Speed PIDIntegral Time could be set to ap-
prox. 2.5 s (varies with the application).
Par. 7-04 Speed PID Differentiation Time should be set to 0 until everything else is tuned. If necessary,
finish the tuning by experimenting with small increments of this setting.
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