Section 8. PID controller
8.2. Limitation of saturation and SLEEP function
When the positive or negative error of regulating is kept some
time it can result in saturation of the PID controller. To prevent this
phenomenon, it is necessary to limit output value of the controller:
•
the lowest output value - par. 2.67 (by default 0.0 %)
•
the highest output value - par. 2.66 (by default 100.0 %)
Function SLEEP of the PID controller enables to shut down automatically
the motor when output value of the PID controller which is simultaneously
the reference of frequency is kept on minimum determined by par. 2.67,
during a time determined by par. 2.70. The drive will be blocked in this
case. Unblocking will occur automatically when one from below conditions
will be fulfilled:
–
the output of a controller will achieve value higher than value par. 2.67 + par. 2.71
–
the error will be higher than par. 2.71
Functioning of limitation and SLEEP blocking is shown in fig. 8.4.
9. Reeler calculator
MFC710 has built-in application of reeler calculator RC (see fig. 9.1).
Application adapts motor's torque to current roller diameter, so that rolling up could be performed with constant force.
For determining current diameter of a roller there is necessary an information about linear speed of rolled medium. In
presented example linear speed signal is obtained from frequency converter which cooperates simultaneously in
production line.
52
Frequency converter MFC710 type. TWERD Power Electronics
Fig. 8.3 - Reaction of a controller to error jump
at the input of the PID controller at the broken
off back coupling on speed
Fig. 8.4 - Illustration of limiting of the PID controller and SLEEP blocking
Fig. 9.1 - Functioning of reeler calculator
Par. 2.70
BLOCK. (STOP)
Par. 2.71
Par. 2.66
Par. 2.67
Output of PID-regulator
Value of OutPID can be read from par. 0.33
time
