Patent ID: 8672640

Claim:
A fan rotation speed control system for controlling a rotation speed of a fan, comprising: a fan rotation speed controller, coupled to the fan, for receiving a signal value to produce a driving voltage to the fan and detecting an actual rotation speed of the fan; and a master controller, coupled to the fan rotation speed controller, for providing the signal value and recalculating the signal value by comparing the actual rotation speed with a target rotation speed, wherein the master controller recalculates the signal value by performing a binary approximation method based on the actual rotation speed and the target rotation speed, wherein the master controller in the binary approximation method further sets at least one transition rotation speed, which equals to an average of the actual rotation speed and the target rotation speed; recalculates the signal value by interpolation based upon the transition rotation speed and the target rotation speed; provides a recalculated signal value to the fan rotation speed controller until the difference between the actual rotation speed and the target rotation speed is within a specific range; and then sends the recalculated signal values in progression until the actual rotation speed reaches the target rotation speed.