Apparatus and method for intelligent control of the fan speed air-cooled condensers

摘要

A refrigeration system (10) has a compressor (12) that forces a refrigerant to flow in a loop between an evaporator (17) and a condenser (16). The present method controls the speed of a condenser fan (16) in response to the condenser temperature. In a first control state, the speed of the fan (16) is varied in response to the condenser temperature. In a second state, the fan (16) is turned on and off by a pulse width modulated signal that has a duty cycle which varies in response to the condenser temperature. A transition occurs from the first state to the second state when the fan (16) operates at the slowest possible speed for a predetermined period while the condenser temperature is below a desired value. A transition occurs from the second state to the first state when the duty cycle is at 100% for a given period and the condenser temperature is above the desired value.