Process Pid Control - Danfoss FC 300 Design Manual

FC 300 Design Guide
Tuning guidelines
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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 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 Max Torque Ripple 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.

Process PID Control

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The Process PID Control can be used to control application parameters that can be measured by a sensor (i.e.
pressure, temperature, flow) and affected by the connected motor through a pump, fan or otherwise.
The table shows the control configurations where Process Control is possible. When a Flux Vector
motor control principle is used, take care also to tune the Speed Control PID parameters. Refer to
the section about the Control Structure to see where the Speed Control is active.
Par. 1-00
Configuration
Mode
[3] Process
Note: The Process Control PID will work under the default parameter setting, but tuning the
parameters is highly recommended to optimize the application control performance. The two
Flux motor control principles are specially dependent on proper Speed Control PID tuning (prior
to tuning the Process Control PID) to yield their full potential.
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Introduction to FC 300
Par. 1-01 Motor Control Principle
U/f VVCplus
N.A. Process
MG.33.B6.22 - VLT is a registered Danfoss trademark
Flux sensorless Flux w motor feedb
Process & Speed Process & Speed