Tuning Speed Pid Control - Danfoss VLT AutomationDrive FC 300 Design Manual

Product Introduction Design Guide

3.4.5 Tuning Speed PID Control

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).
3 3
The value of 30-83 Speed PID Proportional Gain is dependent on the combined inertia of the motor and load. The selected
bandwidth can be calculated using the following formula:
Total inertia kgm 2 x par . 1 − 25
Par . 7 − 02 = x Bandwidth rad / s
Par . 1 − 20 x 9550
NOTICE!
1-20 Motor Power [kW] is the motor power in kilowatts. For example, 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 30-83 Speed PID Proportional Gain calculation against
the following formula. This is not required if using a high resolution feedback such as a SinCos feedback.
0.01 x 4 x Encoder Resolution x Par . 7 − 06
Par . 7 − 02 MAX =
2 x π
x Max torque ripple %
A good starting value for 7-06 Speed PID Lowpass Filter Time is 5 ms. A lower encoder resolution calls for a higher filter
value. Typically a max torque ripple of 3% is acceptable. For incremental encoders, the Encoder Resolution is found in either
5-70 Term 32/33 Pulses Per Revolution (24 V HTL on standard drive) or 17-11 Resolution (PPR) (5 V TTL on MCB102 Option).
Generally the practical maximum limit of 30-83 Speed PID Proportional Gain is determined by the encoder resolution and the
feedback filter time, but other factors in the application might limit the 30-83 Speed PID Proportional Gain to a lower value.
To minimize the overshoot, 7-03 Speed PID Integral Time could be set to approx. 2.5 s. Time varies with the application.
7-04 Speed PID Differentiation Time should be set to 0 until everything else is tuned. If necessary, finish the tuning by
adjusting this setting in small increments.
40 Danfoss A/S © Rev. 2014-02-10 All rights reserved. MG34S222