Answer / www.islamqa.com

Actually we can make it simple:

# P:
it's a controller gain which modify the controller o/p
proportional to the error.

# I:
it's a controller gain which modify the controller o/p
proportional to the integral of the error.

# D:
it's a controller gain which modify the controller o/p
proportional to error rate of change.



We have 4 parameters in our control loop to focus on:
1 - the rise time: the period of time during which the pv
get 90% of the desired sp value
2 - max overshoot
3 - settling time: the period of time during which the pv
get the desired sp value and saturate.
4 - error/offset

we can get it clear from this pic:
http://controls.ame.nd.edu/ame437/S2003/hw1/specifications.j
pg

Now we will take a look about the effect of each controller
gain on these parameters:

# P gain:
decrease rise time
increase max.overshoot
increase settling time
decrease error (but not eliminate)


# I gain:

decrease rise time
increase max.overshoot
increase settling time
eliminate error.


# D gain:

no effect on rise time
decrease max.overshoot
decrease settling time
decrease error.

the previous is guidelines to be in background while
dealing with PID,but they are not sharp limits.

Regards,

Ahmed Sabry
Control and Instrumentation Engineer
GPC - General Petroleum Company
ahmedsabry.online@gmail.com
CELL.: 00 2 0121367310

Answer / moody from egypt

PID CONTROLLER is aproportional integral differential
controller that may b used at any electrical control
application as the response of any system is resulting from
the multiplication of any gain "prop" , diffrentiate
it"diff" and then integrate it.
PSS is the most device at which we design it by PID
either with FLC or using POLE PLACEMENT.
u can make asmall pid using OPERATIONAL AMPLIFIER
OR SIMPLE RLC CIRCUIT.

Answer / hasan mehdi

For PID controller the actuating signal consists of
proportional error signal added with derivative and
integral of the error signal. There fore the actuating
signal for PID control is
ea (t)=e(t)+Td de(t)/dt + Kt}e(t)dt

Answer / sudhir prajapati

Its a one type of feedback system. PID controller try to
correct the error between a measured process variable and
desired set point by calculating and then it generates the
corrective action accordingly

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