Temperature control using PID

HCM UNIVERSITY
OFTECHNOLOGY
FACULTY OF 
ELECTRICAL&ELECTRONICS 

 ENGINEERING
INSTRUCTOR: Dr.HUYNH THAI HOANG
Group15: 1.TRẦN NGUYÊN PHONG 41102558
2.ĐỖMINH KHÔI 41101673
3 ĐOÀN NGỌC MẠNH 41102019.
4.PHẠM ĐỨC TRỌNG 41103848
I I t d ti PID t ll. n ro uc on con ro ers
 The PID controller : most common form feedback.. In process 
control today, more than 95% of the control loops are of PID 
type, most loops are actually PI control. 
 Often combined with logic, sequential functions, selectors, and 
i l f ti bl k t b ild th li t d t tis mp e unc on oc s o u e comp ca e au oma on 
systems used for energy production, transportation, and 
manufacturing.
The transfer function of PID 
controller :
Where: Kp is the proportional gain
TI is the integral time
TD is the derivative time
BLOCK DIAGRAM OF PID CONTROL 
SYSTEM
Effect of increasing a parameter of PID controller
independently on closed-loop performance
Conclusion: PID controllers help speed up
response of system decrease settling time steady state, , -
error and POT.
II. Design system temperature controller by PID:
1.Transfer function of a thermal process:
Caculate the approximate transfer function
•The approximate transfer function of the
thermal process can be calculated by using the
equation:
•The input is the unit step signal then : 
•The approximate output is:
where:
•The Laplace transform of f(t) is:
•Applying the time delay theorem:
2. Manual tuning of PID controllers method:
 Set KI and KD to 0, gradually increase KP to the critical 
gain K-cr
 Set KP= Kcr / 2 
 Gradually increase KI until the steady-state error is 
eliminated in a sufficient time for the process (Note that . 
too much KI will cause instablility).
 Increase KD if needed to reduce POT and settling time. 
(Note that too much KD will cause excessive response and 
oveshoot).
3. Design system temperature controller
Where: 
* Using Manual tuning of PID controllers method:
 We have: 
 Kcr = 0.043
Chose: 
Kp = 0.021
KI = 0.0003
KD = 0.12
R lt i l tiesu s mu a on:
If t d POT d t i K wan ecrease an s, we ncrease d
Air Conditioning PID Control- 
System
 The heating and air-conditioning (HVAC) systems have huge
different characteristics in control engineering from chemical and
steel processes.
 One of the characteristics is that the equilibrium point (or the
operating point) usually varies with disturbances such as outdoor
temperature (or weather conditions) and thermal loads
Dynamic equation of the room’s temperature
Thus, the plant dynanmics including the
AHU and the sensor can be represented by,
Comparing to Equation 1, the plant gain 
(Kp) and the time constant (Tp) can be 
given by
Dynamic equation of the room’s humidity
the plant dynamics concerned with the
room humidity model can be represented
by,
Air-handling unit (AHU) model
Air brought back to the AHU from the room is 
called return air. 
 The portion of the return air discharged to the 
outdoor air is exhaust air and a large part of the , 
return air reused is recirculated air. 
Air brought in intentionally from the outdoor air is 
outdoor air. 
 The outdoor air and the recirculated air are mixed 
to form mixed air, which is then conditioned and 
Dynamics of the humidifier can be 
described by
Room temperature control system
Room humidity control system
REFERENCES
 Advanced PID Cotrol Karl J.Astrom
 Stability  Limit of  Room air Temperature of a VAV 
systems(1998).                           Matsubu.T.et al
 Stability of tempe(2009)          Yamakawa.Y.et al
Thank you!