Coordinating Cooling Fans

Abstract

In one example in accordance with the present disclosure a system for coordinating cooling fans in a housing includes a first fan for cooling a power supply; a second fan; a control board to provide a first pulsed wave modulated (PWM) signal to the second fan; and a logic element to provide a control signal to the first fan based on a second PWM signal from the power supply and a third PWM signal from the control board.

What is claimed is: 
     
         1 . A system for coordinating cooling fans, the system comprising:
 a first fan for cooling a power supply;   a second fan;   a control board to provide a first pulsed wave modulated (PWM) signal to the second fan; and   a logic element to provide a control signal to the first fan based on a second PWM signal from the power supply and a third PWM signal from the control board.   
     
     
         2 . The system of  claim 1 , further comprising a lookup table which indexes the third PWM signal to the first PWM signal. 
     
     
         3 . The system of  claim 1 , wherein the second PWM signal is independent of the third and first PWM signals. 
     
     
         4 . A system for coordinating cooling fans in a housing, the system comprising:
 a first fan;   an OR-logic element that outputs a control signal to the first fan;   a power supply to provide a first pulsed wave modulated (PWM) signal to the OR-logic; and   a controller to provide a second PWM signal to the OR-logic,   wherein the second PWM signal is used to increase a duty cycle applied to the first fan so as to prevent backflow in air circulation when a second fan is operated.   
     
     
         5 . The system of  claim 4 , wherein the OR-logic controls an electrical connection between the first fan and a power source to power the first fan. 
     
     
         6 . The system of  claim 4 , wherein the OR-logical element comprises a transistor. 
     
     
         7 . The system of  claim 4 , wherein the first pulsed width modulated signal has a lower duty cycle than the second PWM signal. 
     
     
         8 . The system of  claim 4 , wherein the first fan operates when the controller is unpowered. 
     
     
         9 . The system of  claim 4 , wherein the second PWM signal is provided on a line of a multiline connection between the controller and the power supply. 
     
     
         10 . The system of  claim 4 , wherein the OR-logic is within the power supply. 
     
     
         11 . A method for controlling a power supply unit (PSU) fan, the method comprising:
 providing a pulse width modulated (PWM) signal via a power line to regulate a speed of the fan, wherein the PWM signal is formed using a PWM signal from a power supply and a PWM signal from a control board.   
     
     
         12 . The method of  claim 11 , wherein the PWM signal from the control board varies based on an input to a second fan. 
     
     
         13 . The method of  claim 11 , wherein the PWM signal from the control board is regulated so as to prevent backflow of air through the power supply unit fan. 
     
     
         14 . The method of  claim 11 , wherein the PWM signal from the control board is provided on a channel of a multi-channel connector between the control board and the power supply. 
     
     
         15 . The method of  claim 11 , wherein the PWM signal is output by an OR-logic element receiving the PWM signal from a power supply and the PWM signal from a control board.