Cooling fan control device and control method thereof

Abstract

Disclosed herein are a cooling fan driving control device and a control method thereof non-linearly controlled to a duty ratio (%) of a PWM signal. The cooling fan driving control device includes a cooling fan control device including a temperature sensor, a microprocessor unit generating a PWM signal corresponding to a temperature measured by the temperature sensor, and a cooling fan driving unit driving the cooling fan according to a duty ratio of the PWM signal, comprising: a duty ratio detection unit receiving the PWM signal from the microprocessor unit to detect the duty ratio (%) of the PWM signal; and a duty ratio control device comparing the duty ratio (%) detected from the duty ratio detection unit with a predetermined threshold value, controlling the duty ratio (%) of the PWM signal according to the comparison results, and then, outputting the controlled PWM signal to the cooling fan driving unit.

What is claimed is: 
     
         1 . A cooling fan control device including a temperature sensor, a microprocessor unit generating a PWM signal corresponding to a temperature measured by the temperature sensor, and a cooling fan driving unit driving the cooling fan according to a duty ratio of the PWM signal, comprising:
 a duty ratio detection unit receiving the PWM signal from the microprocessor unit to detect the duty ratio (%) of the PWM signal; and   a duty ratio control device comparing the duty ratio (%) detected from the duty ratio detection unit with a predetermined threshold value, controlling the duty ratio (%) of the PWM signal according to the comparison results, and then, outputting the controlled PWM signal to the cooling fan driving unit.   
     
     
         2 . The cooling fan control device according to  claim 1 , wherein the duty ratio control device controls the duty ratio (%) of the PWM signal by comparing the duty ratio (%) detected from the duty ratio detection unit with the predetermined threshold value and adding and subtracting the predetermined duty ratio control value to and from the detected duty ratio (%) of the PWM signal according to the comparison results. 
     
     
         3 . The cooling fan control device according to  claim 1 , wherein the duty control device adds the duty ratio control value to the detected duty ratio (%) of the PWM signal when the duty ratio (%) detected from the duty ratio detection unit is a predetermined first threshold value or more; and
 subtracts the duty ratio control value from the detected duty ratio (%) of the PWM signal when the duty ratio (%) detected from the duty ratio detection unit is a predetermined second threshold value or less,   the first threshold value being larger than the second threshold value.   
     
     
         4 . The cooling fan control device according to  claim 3 , wherein the first threshold value is any one of 70% to 90%,
 the second threshold value is any one of 10% to 30%, and   the duty ratio control value is any one of 1% to 10%.   
     
     
         5 . The cooling fan control device according to  claim 1 , further comprising a PWM signal generation unit generating a new PWM signal by receiving the PWM signal from the duty ratio control device and changing a frequency of the PWM signal according to a predetermined frequency value. 
     
     
         6 . The cooling fan control device according to  claim 5 , wherein the PWM signal generation unit performs a function of setting the duty ratio (%) of the PWM signal to a lowest threshold value when the duty ratio (%) of the PWM signal received from the duty ratio control device is a predetermined lowest threshold value or less. 
     
     
         7 . A cooling fan speed control method, comprising:
 (a) receiving a PWM signal generated corresponding to temperature measured by a temperature sensor;   (b) detecting a duty ratio (%) of the PWM signal;   (c) comparing the duty ratio (%) detected at the detecting of the duty ratio with a predetermined first threshold value;   (d) when the duty ratio (%) detected at the comparing of the duty ratio is below the predetermined first threshold value, comparing it with the predetermined second threshold value; and   (e) generating a new PWM signal by changing the frequency of the PWM signal according to the predetermined frequency value when the duty ratio (%) exceeds the predetermined second threshold value at the comparing of the duty ratio (%),   wherein the first threshold value is larger than the second threshold value.   
     
     
         8 . The cooling fan speed control method according to  claim 7 , further comprising: at the comparing of the duty ratio, when the detected duty ratio (%) is the predetermined first threshold value or more, adding the predetermined duty ratio control value to the detected duty ratio (%) of the PWM signal; and
 generating a new PWM signal by changing a frequency of the controlled PWM signal according to a predetermined frequency value.   
     
     
         9 . The cooling fan speed control method according to  claim 7 , further comprising: at the comparing, when the detected duty ratio (%) is the predetermined second threshold value or less,
 subtracting the predetermined duty ratio control value from the detected duty ratio (%) of the PWM signal;   comparing the controlled duty ratio (%) of the PWM signal with a lowest threshold value; and   generating a new PWM signal by changing the fixed frequency of the PWM signal according to the predetermined frequency value when the controlled duty ratio (%) of the PWM signal exceeds the lowest threshold value.   
     
     
         10 . The cooling fan speed control method according to  claim 9 , further comprising:
 fixing the controlled duty ratio (%) of the PWM signal to a lowest threshold value when the controlled duty ratio (%) of the PWM signal is the lowest threshold value; and   generating the new PWM signal by changing the controlled frequency of the PWM signal according to the predetermined frequency value.