Figure 22. Pid Controller Fundamentals - Intel QX9770 - Core 2 Extreme Quad-Core Processor Design Manual

Intel® Quiet System Technology (Intel® QST)

Figure 22. PID Controller Fundamentals

For a PID algorithm to work limit temperatures are assigned for each temperature
sensor. For Intel QST the T
limit temperature. The ME will measure the error, slope and rate of change using the
equations below:
• Proportional Error (P) = T
• 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
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
Integral (time averaged) Integral (time averaged) Integral (time averaged) Integral (time averaged)
CONTROL
LIMIT
®
Quiet System Technology (Intel
Actual Actual
Temperature Temperature
Limit Limit
Proportional Proportional Proportional Proportional
Temperature Temperature
Error Error Error Error
Derivative (Slope) Derivative (Slope) Derivative (Slope) Derivative (Slope)
Time
Fan Fan
Speed Speed
for the processor and chipset are to be used as the
– T
ACTUAL
®
QST) Configuration and Tuning Manual
59