Sensor-free optimal control of air-side economizer

Abstract

Systems and methods to regulate the amount of outdoor air that is introduced into a building. These systems and methods use the cooling coil control signal which is a function of the load on the cooling coil. These systems and methods utilize extremum seeking control logic to vary the flow of outdoor air into the building in response to these load determinations.

1 . A method for operating a system which regulates an amount of outdoor air that is introduced into a building and operates a mechanical temperature control device that varies temperature in the building, the method comprising:
 initiating a heating with minimum outdoor air state;   monitoring a heating control signal, a cooling control signal and a damper control signal;   performing a state comparison of the heating control signal, the cooling control signal and the damper control signal to a predetermined range of values; and   transitioning into a second state based on the comparison.   
   
   
       2 . The method as recited in  claim 1 , wherein the system includes a single sensor. 
   
   
       3 . The method as recited in  claim 2 , wherein the single sensor is a supply air temperature sensor. 
   
   
       4 . The method as recited in  claim 1 , wherein an extremum seeking control circuit is used for varying the flow of outdoor air into the building. 
   
   
       5 . The method as recited in  claim 1 , wherein the predetermined range of values is based on a geographic region. 
   
   
       6 . The method as recited in  claim 1 , wherein the predetermined range of values is based on a system maintenance. 
   
   
       7 . The method as recited in  claim 1 , wherein the predetermined range of values is based on a system configuration. 
   
   
       8 . The method as recited in  claim 1 , wherein the predetermined range of values is based on a system design. 
   
   
       9 . The method as recited in  claim 1 , wherein performing the state comparison of the heating control signal, the cooling control signal and the damper control signal to a predetermined range of values is initiated on a predetermined interval for at least the first state. 
   
   
       10 . The method as recited in  claim 9 , wherein the at least first state comprises the heating with minimum outdoor state, a free cooling state and a mechanical cooling with self-optimizing control state. 
   
   
       11 . A method for operating a system which regulates an amount of outdoor air that is introduced into a building and operates a mechanical temperature control device that varies temperature in the building, the method comprising:
 initiating a heating with minimum outdoor air state;   monitoring a heating control signal, a cooling control signal and a damper control signal;   performing a state comparison of the heating control signal, the cooling control signal and the damper control signal to a predetermined range of values;   transitioning into a second state based on the comparison; and   wherein the predetermined range of values includes: (i) the heating control signal is at a heating minimum value for five minutes or the cooling control signal is at a cooling minimum value for five minutes to transition to a free cooling state; (ii) the damper control signal at a damper minimum value for five minutes to transition to the heating with minimum outdoor air state; and (iii) the damper control signal at a damper maximum value for five minutes to transition to a mechanical cooling with self-optimizing control state.   
   
   
       12 . The method as recited in  claim 11 , wherein the system includes a single sensor. 
   
   
       13 . The method as recited in  claim 11 , wherein the single sensor is a supply air temperature sensor. 
   
   
       14 . The method as recited in  claim 11 , wherein an extremum seeking control circuit is used for varying the flow of outdoor air into the building. 
   
   
       15 . The method as recited in  claim 11 , wherein performing the state comparison of the heating control signal, the cooling control signal and the damper control signal to a predetermined range of values is initiated on a predetermined interval for at least the first state. 
   
   
       16 . The method as recited in  claim 15 , wherein the at least first state comprises the heating with minimum outdoor state, a free cooling state and a mechanical cooling with self-optimizing control state. 
   
   
       17 . A method for operating a system which regulates an amount of outdoor air that is introduced into a building and operates a mechanical temperature control device that varies temperature in the building, the method comprising:
 initiating a heating with minimum outdoor air state;   monitoring a heating control signal, a cooling control signal and a damper control signal;   performing a state comparison of the heating control signal, the cooling control signal and the damper control signal to a predetermined range of values;   transitioning into a second state based on the comparison; and   wherein the predetermined range of values includes: (i) the heating control signal is at a heating minimum value for a first predetermined interval or the cooling control signal is at a cooling minimum value for second predetermined interval to transition to a free cooling state; (ii) the damper control signal at a damper minimum value for a third predetermined interval to transition to the heating with minimum outdoor air state; and (iii) the damper control signal at a damper maximum value for a fourth predetermined interval to transition to a mechanical cooling with self-optimizing control state.   
   
   
       18 . The method as recited in  claim 15 , wherein the first predetermined interval, the second predetermined interval, the third predetermined interval and the fourth predetermined interval are configured to vary based on an user input. 
   
   
       19 . The method as recited in  claim 15 , wherein the first predetermined interval, the second predetermined interval, the third predetermined interval and the fourth predetermined interval are equal. 
   
   
       20 . The method as recited in  claim 15 , wherein the first predetermined interval, the second predetermined interval, the third predetermined interval and the fourth predetermined interval are configured to vary based on a system design. 
   
   
       21 . A space conditioning device comprising:
 an air-handling unit;   a means for cooling an air coupled to the air-handling unit;   a means for heating the air coupled to the air-handling unit;   a means for controlling the space conditioning device;   at least one means for controlling a flow of the air coupled to the means for controlling the space conditioning device and the air-handling unit;   wherein the means for controlling the space conditioning device in a start up stage initiates a heating with minimum outdoor air state; and   wherein the means for controlling the space conditioning device is configured to control the at least one means for controlling the flow of the air utilizing extremum logic.   
   
   
       22 . The space conditioning device as recited in  claim 21 , wherein the system includes a single sensor. 
   
   
       23 . The space conditioning device as recited in  claim 22 , wherein the single sensor is a supply air temperature sensor. 
   
   
       24 . The space conditioning device as recited in  claim 21 , wherein an extremum seeking control circuit is used for varying a flow of outdoor air into a building.