1. PID Control & ACS550 and ACH550

2. PID in every day life Cruise function in a car:
User sets the speed (Input = SetPoint = Reference)
Car measures (Feedback = Actual)
Car automatically minimizes the error (Deviation) between these two (Input and Feedback)
”…as a result is a smooth ride.”

3. PID: General Widely used in automation and process industries.
Applications:
Motor Speed Control
Pressure & Temperature Control
Flow Control
(Water) Level Control

4. PID: General Proportional-integral-derivative (PID) controller.
Control loop feedback method:
VSD (controller) compares the reference signal (input) to the actual signal (feedback) and controls the speed of the drive according to the difference (error) of these signals.

5. PID: General PID algorithm includes three different variables:
P(roportional): Proportional reaction to the error of the reference and measured signals: improves the rise time!
I(ntegral): Determines the accumumulated proportional offset over time: eliminates the steady state error!
D(erivative): Anticipated control: determines the slope of the error signal.
Reduces the overshoot of the integral component.

6. PID: General
The output (v) of the PID controller: P I D

7. Increasing variable’s value
PID: General
Effects of controllers (P, I, D):
When increasing the value of the variables…
CLOSE LOOP RESPONSE
Increasing variable’s value
RISE TIME
OVERSHOOT
SETTLING TIME
STEADY-STATE ERROR Kp
Decreases
Increases
Small Change KI
Eliminates KD
Decrease
None
Remember that the variables are dependent on each
other and thus by changing one value you might effect on the others!
The table above is only a good reference! ! !

8. PID: Tuning Traditional Ziegler-Nichols method:
Pure P controller (disable D and I)
Increase the gain untill the system oscillates (critical gain KC)
Read the oscillation period Tc
Calculate the values according to the table below:
Controller P I D
P 0.5KC
PI 0.4KC 0.8TC
PID 0.6KC 0.5TC 0.125TC

9. PID: General Control type by application: Level Control: Usually P
Flow & Pressure & Temperature Control: PI
Motor Speed Control: PID

10. PID: General Using PID can be served: SMOOTH AND FAST SYSTEM!!!
Fast response/rise time
No overshoot
Low steady-state error
SMOOTH AND FAST SYSTEM!!!

11. PID: General
Sometimes all three controllers are not needed to obtain a good response!
Depending on the system a good enough control can be achieved by using only PI controller!
Always keep the system as simple as possible!

12. PID: ACS550 PID functions available both on ACS550 and ACH550
ACS550: PID control
Groups:
40 (Process PID SET 1)
41 (Process PID SET 2) and
42 (EXT / TRIM PID)
Pre-defined PID control macro:
Set 9902
PID Assistant

13. PID: ACS550
PID control macro: (9902)

14. PID: ACH550 ACH550: PID controller is in every HVAC macro. Groups:
40 (Process PID SET 1)
41 (Process PID SET 2) and
42 (EXT / TRIM PID)
Macro selections:
Set 9902
PID Assistant

15. PID: ACS550 and ACH550
ACS550 and ACH550 schematic of reference signal using parameter group 40:
In order to use PID controller, parameter 1106 must set to EXT2 (19).

16. PID: ACS550 and ACH550 Parameters 4001-4009: Used to adjust the PID:
Param. 4001: GAIN
Param. 4002: INTEGRATION TIME
Param. 4003: DERIVATION TIME …

17. PID: ACS550 and ACH550 Rule of thumb in parameter setting:
PID GAIN (parameter 4001)
increase until the system starts to oscillate
right value is half of this
PID INTEG TIME (parameter 4002)
decrease until the system starts to oscillate
right value is 2*Ti

18. PID: Summary What is it for the customer?! Accurate:
Quality of the Process and Goods
Easiness: (PID Macro)
Time Savings
Extent in Use:
Compatibility
Maintenance & Support