Process Pid Control - Danfoss FC 300 Design Manual

FC 300 Design Guide
3.3.2. Tuning PID speed 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).
The value of par. 7-02 proportional gain is dependent on the combined inertia of the motor and
load, and the selected bandwidth can be calculated using the following formula:
Par
. 7 − 02 =
Note: Par. 1-20 is the motor power in [kW] (i.e., enter '4' kW instead of '4,000' 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):
Par
. 7 − 02
A good start value for par. 7-06
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 the par. 7-02
Gain
to a lower value.
To minimize the overshoot, par. 7-03
application).
Par. 7-04
the tuning by experimenting with small increments of this setting.

3.3.3. Process PID Control

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
vmotor 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 Configu-
ration Mode
[3] Process
Note: 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 dependant on proper speed control PID tuning (prior to tuning the process
control PID) to yield their full potential.
Total inertia k gm
Par
. 1 − 20
x x Encoder Resolution x par
0.01 4
=
MAXIMUM
Speed Filter Time
Integral Time
Differential Time
should be set to 0 until everything else is tuned. If necessary, finish
Par. 1-01 Motor Control Principle
U/f
N.A.
MG.33.B9.22 - VLT ® is a registered Danfoss trademark.
2
x Par
. 1 − 25
x Bandwidth rad
x
9550
x
2 π
is 5 ms (lower encoder resolution calls for a
could be set to approx. 2.5 s (varies with the
Flux sensorless
VVC plus
Process Process & Speed
3. Introduction to FC 300
s
/
. 7 − 06
x Max torque ripple
Proportional
Flux w/ enc. feedb
Process & Speed
3
%
35