Process Pid Control - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide
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 Bandwith 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 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 the par. 7-02 Proportional Gain to a lower value.
To minimize the overshoot, par. 7-03 Integral Time could be set to approx. 2.5 s (varies with the application).
Par. 7-04 Differential 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 be affected by the connected motor through a pump, fan or otherwise.
The table shows the control configurations where the 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 optimise the application control performance. The two
Flux motor control principles are specially dependant on proper Speed Control PID tuning (prior
to tuning the Process Control PID) to yield their full potential.
Process PID Control diagram
Introduction to FC 300
Par. 1-01 Motor Control Principle
U/f VVCplus
N.A. Process
MG.33.B4.02 - VLT is a registered Danfoss trademark
Flux Sensorless Flux w/ enc.
feedb
Process & Speed Process & Speed
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