Intel Q9400S Design Guidelines - Page 59

Temperature

Page 59 highlights

Intel® Quiet System Technology (Intel® QST) Temperature - dPWM Figure 20. PID Controller Fundamentals Integral (time averaged) Actual Temperature Proportional Error Limit Temperature Derivative (Slope) + dPWM Time Fan Speed RPM For a PID algorithm to work, limit temperatures are assigned for each temperature sensor. For Intel QST, the TCONTROL for the processor and chipset are to be used as the limit temperature. The ME will measure the error, slope and rate of change using the equations below:  Proportional Error (P) = TLIMIT - TACTUAL  Integral (I) = Time averaged error  Derivative (D) = ΔTemp / ΔTime Three gain values are used to control response of algorithm.  Kp = proportional gain  Ki = Integral gain  Kd = derivative gain The Intel® Quiet System Technology (Intel® QST) Configuration and Tuning Manual provides initial values for the each of the gain constants. In addition it provides a methodology to tune these gain values based on system response. Finally the fan speed change will be calculated using the following formula: ΔPWM = -P*(Kp) - I*(Ki) + D*(Kd) Thermal and Mechanical Design Guidelines 59

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Intel® Quiet System Technology (Intel® QST)
Thermal and Mechanical Design Guidelines
59
Figure 20. PID Controller Fundamentals
Derivative (Slope)
Integral (time averaged)
Derivative (Slope)
Integral (time averaged)
Derivative (Slope)
Integral (time averaged)
Proportional
Error
Derivative (Slope)
Integral (time averaged)
RPM
Temperature
Time
+ dPWM
+ dPWM
-
dPWM
dPWM
Actual
Temperature
Actual
Temperature
Fan
Speed
Fan
Speed
Limit
Temperature
Limit
Temperature
For a PID algorithm to work, limit temperatures are assigned for each temperature
sensor. For Intel QST, the T
CONTROL
for the processor and chipset are to be used as the
limit temperature. The ME will measure the error, slope and rate of change using the
equations below:
Proportional Error (P) = T
LIMIT
– T
ACTUAL
Integral (I) = Time averaged error
Derivative (D) =
Δ
Temp /
Δ
Time
Three gain values are used to control response of algorithm.
Kp = proportional gain
Ki = Integral gain
Kd = derivative gain
The
Intel
®
Quiet System Technology (Intel
®
QST) Configuration and Tuning Manua
l
provides initial values for the each of the gain constants. In addition it provides a
methodology to tune these gain values based on system response.
Finally the fan speed change will be calculated using the following formula:
Δ
PWM = -P*(Kp) – I*(Ki) + D*(Kd)