Variable Speed Outdoor Fan Control

Abstract

A method and apparatus for setting the speed of a fan during operation of an HVAC system are provided. The HVAC system may comprise a heat exchanger, a fan, and a sensor disposed within an outdoor unit of the HVAC system. A controller coupled to the fan and sensor may receive a first signal from the sensor indicating one or more ambient air temperature values and determine a desired speed setting of the fan using at least the one or more ambient air temperatures indicated by the first signal. The controller may further generate a control signal based on the desired speed setting and transmit the control signal to the first fan.

1 . An apparatus, comprising:
 a heat exchanger disposed within an outdoor unit of an HVAC system;   a fan disposed within the outdoor unit and configured to cause movement of ambient air within the outdoor unit when operating;   a sensor configured to sense ambient air temperatures; and   a controller operably coupled to the fan and the sensor, the controller comprising a memory having instructions configured to:
 receive a first signal from the sensor, the first signal indicating one or more ambient air temperature values; 
 determine a desired speed setting of the fan using at least the one or more ambient air temperatures indicated by the first signal; 
 generate a control signal based on the desired speed setting, the control signal configured to drive the fan at the desired speed; and 
 transmit the control signal to the first fan. 
   
     
     
         2 . The apparatus of  claim 1 , wherein the desired speed setting corresponds to a desired rate of ambient air movement within the outdoor unit. 
     
     
         3 . The apparatus of  claim 1 , wherein the desired speed setting is determined using at least a first correlation equation relating the one or more ambient air temperature values indicated by the first signal to a corresponding speed setting of the fan. 
     
     
         4 . The apparatus of  claim 3 , wherein the first correlation equation comprises a linear equation relating ambient air temperatures to speed settings of the fan. 
     
     
         5 . The apparatus of  claim 1 , wherein the desired speed setting is determined using a lookup table relating ambient air temperatures to speed settings of the fan. 
     
     
         6 . The apparatus of  claim 1 , wherein the fan comprises an electronic commutation motor. 
     
     
         7 . The apparatus of  claim 1 , wherein the first sensor is a thermistor. 
     
     
         8 . The apparatus of  claim 1 , further comprising:
 a first compressor and a second compressor, the first and second compressors operable independently from one another;   wherein the controller is operably coupled to each of the first and second compressors and the instructions are further configured to:
 determine an operating status for each of the first compressor and the second compressor; and 
 if the first compressor is operating while the second compressor is not operating, determine the desired speed setting of the fan using at least a first correlation equation relating the one or more ambient air temperature values indicated by the first signal to a corresponding speed setting of the fan; and 
 if both the first and second compressors are operating, determine the desired speed setting of the fan using at least a second correlation relating the one or more ambient air temperature values indicated by the first signal to a corresponding speed setting of the fan. 
   
     
     
         9 . A method, comprising:
 receiving, at a controller of an HVAC system, a first signal from a first sensor indicating one or more ambient air temperature values;   determining, using the controller, a desired speed setting of a fan coupled to an outdoor unit of the HVAC system using at least the one or more ambient air temperatures indicated by the first signal;   generating, using the controller, a control signal for at least setting a speed of the fan to the desired speed setting; and   transmitting, using the controller, the control signal to the fan.   
     
     
         10 . The method of  claim 9 , wherein the desired speed setting is the speed setting of the fan corresponding to a desired rate of ambient air movement within the outdoor unit. 
     
     
         11 . The method of  claim 9 , wherein the desired speed setting of the fan is determined using at least a first correlation equation relating at least the ambient air temperatures indicated by the first signal to a corresponding speed setting of the fan. 
     
     
         12 . The method of  claim 11 , wherein the first correlation equation comprises a linear equation relating ambient air temperatures to speed settings of the fan. 
     
     
         13 . The method of  claim 9 , wherein the desired speed setting of the fan is determined using first a lookup table relating ambient air temperatures to speed settings of the fan. 
     
     
         14 . The method of  claim 9 , wherein the fan comprises an electronic commutation motor. 
     
     
         15 . The method of  claim 9 :
 wherein the HVAC system further comprises a first compressor and a second compressor, the first and second compressors operable independently from one another and the controller is operably coupled to each of the first compressor and the second compressor; and   wherein the method further comprises:
 determining the operating status for each of the first compressor and the second compressor; and 
 if the first compressor is operating while the second compressor is not operating, determining the desired speed setting of the fan using at least a first correlation equation relating the one or more ambient air temperature values indicated by the first signal to a corresponding speed setting of the fan; and 
 if both the first and second compressors are operating, determining the desired speed setting of the fan using at least a second correlation relating the one or more ambient air temperature values indicated by the first signal to a corresponding speed setting of the fan. 
   
     
     
         16 . A computer-readable medium comprising instructions configured, when executed by a processor to:
 receive a first signal from a sensor, the first signal indicating one or more ambient air temperature values;   determine, using at least the one or more ambient air temperatures indicated by the first signal, a desired speed setting of a fan using at least the one or more ambient air temperatures indicated by the first signal;   generate a control signal based on the desired speed setting, the control signal configured to drive the fan at the desired speed; and   transmit the control signal to the first fan.   
     
     
         17 . The computer-readable medium of  claim 16 , wherein the desired speed setting corresponds to a desired rate of ambient air movement within the outdoor unit. 
     
     
         18 . The computer-readable medium of  claim 16 , wherein the desired speed setting is determined using at least a first correlation equation relating the one or more ambient air temperature values indicated by the first signal to a corresponding speed setting of the fan. 
     
     
         19 . The computer-readable medium of  claim 18 , wherein the first correlation equation comprises a linear equation relating ambient air temperatures to speed settings of the fan. 
     
     
         20 . The computer-readable medium of  claim 16 , wherein the desired speed setting is determined using a lookup table relating ambient air temperatures to speed settings of the fan.