Fan power supply control system

Abstract

A fan power supply control system includes a power supply module, a power control circuit, a signal control circuit, a PWM generator. The power supply is adapted to input a power signal to a fan. The power control circuit is between the power supply module and the fan and adapted to connect or disconnect the power supply module to the fan. The signal control circuit is connected the power supply module to the power control circuit and adapted to switch on or off the power control circuit. The PWM generator is adapted to generate a predetermined cycle square signal according to the power signal, to intermittently switch on or off the signal control circuit, and a switch on/off state of the power control circuit is synchronous with the signal control circuit.

What is claimed is: 
     
         1 . A fan power supply control system comprising:
 a power supply module adapted to input a power signal to a fan; and   a power control circuit being between the power supply module and the fan, and the power control circuit adapted to connect or disconnect the power supply module to the fan;   a signal control circuit connected the power supply module to the power control circuit, and the signal control circuit adapted to switch on or off the power control circuit; and   a pulse width modulation (PWM) generator adapted to generate a predetermined cycle square signal according to the power signal, to intermittently switch on or off the signal control circuit, and a switching on/off state of the power control circuit being synchronous with the signal control circuit.   
     
     
         2 . The fan power supply control system of  claim 1 , further comprising a filtering circuit electrically connected to the power supply module and the power control circuit, wherein the filtering circuit is adapted to filter the power signal. 
     
     
         3 . The fan power supply control system of  claim 2 , wherein the filtering circuit comprises a first capacitor, a first end of the first capacitor is electrically connected to a positive electrode of the power supply module, and a second end of the first capacitor is grounded. 
     
     
         4 . The fan power supply control system of  claim 1 , wherein the power control circuit comprises a first resistor and a second capacitor, and the first resistor and the second capacitor are in parallel. 
     
     
         5 . The fan power supply control system of  claim 4 , wherein the power control circuit further comprises a first MOSFET, and a source electrode of the first MOSFET is electrically coupled to a first end of the first resistor, a grid electrode of the first MOSFET is electrically connected to a second end of the first resistor and the signal control circuit, and the drain electrode of the first MOSFET is connected to fan. 
     
     
         6 . The fan power supply control system of  claim 5 , wherein the signal control circuit is a second MOSFET, a drain electrode of the second MOSFET is electrically connected to the grid electrode of the second MOSFET, a grid electrode of the second MOSFET is electrically connected to a second resistor, and a source electrode of the second MOSFET is grounded. 
     
     
         7 . The fan power supply control system of  claim 6 , wherein a first end of the second resistor is coupled to the PWM generator and the grid electrode of the second MOSFET, and the second end of the second resistor is connected to a work voltage. 
     
     
         8 . The fan power supply control system of  claim 5 , further comprising a charging and discharging circuit connected to the first MOSFET and the fan, wherein the charging and discharging comprises a third resistor, a diode, a third capacitor, and the a fourth capacitor, and the third resistor, the diode, the third capacitor and the fourth capacitor are in parallel. 
     
     
         9 . The fan power supply control system of  claim 8 , wherein a positive electrode of the diode is grounded, and the negative electrode of the diode is connected to the drain electrode of the first MOSFET. 
     
     
         10 . The fan power supply control system of  claim 6 , wherein the power signal has a current spike, the PWM generator is adapted to generate a low level signal to switch off the second MOSFET when the power signal is in the current spike. 
     
     
         11 . A fan power supply control system comprising:
 a power supply module adapted to input a power signal to a fan; and   a power control circuit being between the power supply module and the fan;   a signal control circuit connected the power supply module to the power control circuit; and   a PWM generator adapted to generate a predetermined cycle square signal according to the power signal, to intermittently switch on or off the signal control circuit,   wherein the signal control circuit is switched on when the PWM generator generates a high level signal, and the power control circuit switches on to connect the power supply module to the fan; the signal is switched off when the PWM generator generates a low level signal, and the power control circuit is switched off to disconnect the power supply module from the fan.   
     
     
         12 . The fan power supply control system of  claim 11 , further comprising a filtering circuit electrically connected to the power supply module and the power control circuit, wherein the filtering circuit is adapted to filter the power signal. 
     
     
         13 . The fan power supply control system of  claim 12 , wherein the filtering circuit comprises a first capacitor, a first end of the first capacitor is electrically connected to a positive electrode of the power supply module, and a second end of the first capacitor is grounded. 
     
     
         14 . The fan power supply control system of  claim 11 , wherein the power control circuit comprises a first resistor and a second capacitor, and the first resistor and the second capacitor are in parallel. 
     
     
         15 . The fan power supply control system of  claim 14 , wherein the power control circuit further comprises a first MOSFET, and a source electrode of the first MOSFET is electrically coupled to a first end of the first resistor, a grid electrode of the first MOSFET is electrically connected to a second end of the first resistor and the signal control circuit, and the drain electrode of the first MOSFET is connected to fan. 
     
     
         16 . The fan power supply control system of  claim 15 , wherein the signal control circuit is a second MOSFET, a drain electrode of the second MOSFET is electrically connected to the grid electrode of the second MOSFET, a grid electrode of the second MOSFET is electrically connected to a second resistor, and a source electrode of the second MOSFET is grounded. 
     
     
         17 . The fan power supply control system of  claim 16 , wherein a first end of the second resistor is coupled to the PWM generator and the grid electrode of the second MOSFET, and the second end of the second resistor is connected to a work voltage. 
     
     
         18 . The fan power supply control system of  claim 15 , further comprising a charging and discharging circuit connected to the first MOSFET and the fan, wherein the charging and discharging comprises a third resistor, a diode, a third capacitor, and the a fourth capacitor, and the third resistor, the diode, the third capacitor and the fourth capacitor are in parallel. 
     
     
         19 . The fan power supply control system of  claim 18 , wherein a positive electrode of the diode is grounded, and the negative electrode of the diode is connected to the drain electrode of the first MOSFET. 
     
     
         20 . The fan power supply control system of  claim 16 , wherein the power signal has a current spike, the PWM generator is adapted to generate a low level signal to switch off the second MOSFET when the power signal is in the current spike.