THORLABS ITC1 Series, Operation Manual

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© 2018 Thorlabs GmbH 22
ITC1xx
4.7 PID Adjustment
A temperature control loop works comparably slow. Regulation oscillations have a period in the
range of seconds.
The PID adjustment will optimize the dynamic behavior. The ITC1xx temperature controller al-
lows the three control loop parameters P, I and D to be set independently from 5% to 100%.
Example of a PID adjustment
Pre-condition:
All limit values are set correctly, all polarities are correct, all set and relevant calibration values
are entered, ambient temperature is about 20 °C.
·
Switch off the I share ( switch S4 to OFF).
·
Set the P, I and D share to minimum (turn P5, P6 and P7 fully counter clockwise).
·
Observe the actual temperature T
ACT
or the actual thermistor resistance R
ACT
( ST1 pin
C10 ) and switch on the temperature controller.
P share
·
Change the set temperature repeatedly between about 18 °C and 22 °C while observing
the settling behavior of the actual temperature.
·
Increase the P share gradually. Higher values will increase the settling speed, too high
values lead to regulation oscillations.
·
The P share has been set correctly if after only 2-3 overshoots the actual temperature re-
mains stable close to the set temperature.
D share
·
Change the set temperature repeatedly between about 18 °C and 22 °C while observing
the settling behavior of the actual temperature.
·
Increase the D share gradually. Higher values will decrease the amplitude of the over-
shoots.
·
The D share is set correctly when the actual temperature remains stable close to the set
temperature after a minimum of overshoots.
I share
·
Turn on the I share (switch S4 to ON).
·
Change the set temperature repeatedly between about 18 °C and 22 °C while observing
the settling behavior of the actual temperature.
·
Increase the I share gradually. Higher values will accelerate the settling to the set temper-
ature.
·
The I share is set correctly when the actual temperature reaches the set temperature in
shortest time without overshoots.
Note
In case of a high thermal load, the adjustment ranges of the I and D shares might be insuffi-
cient. The adjustment range can be increased by using
additional foil capacitors : C73 for the D
share and C75,C76 and C77 for the I share, typically 0.47 µF to 3.3 µF.