Systems and methods for electronic expansion valve control
An HVAC system includes, an electronic expansion valve (EEV), and a controller in communication with the EEV. The controller determines a minimum EEV setpoint position value based on a comparison of a superheat error value to a setpoint error threshold. The controller determines a maximum EEV setpoint position value based on a comparison of a second superheat error value to a second setpoint error threshold. The controller calculates an average setpoint value based on the maximum EEV setpoint position value and the minimum EEV setpoint position value. The controller configures the EEV to a position corresponding to the average setpoint value and operate the EEV for a predetermined amount of time. The controller operates the EEV according to a PID algorithm.
1. A system comprising:
an electronic expansion valve configured to control a flow of refrigerant through a refrigerant line; and
an outdoor unit controller in communication with the electronic expansion valve, and configured to:
determine a first electronic expansion valve position value by recording a valve position value of the electronic expansion valve when a superheat of the refrigerant in the refrigerant line is determined to be at a minimum superheat value;
determine a second electronic expansion valve position value by recording the electronic expansion valve position value when the superheat of the refrigerant in the refrigerant line is determined to be at a maximum superheat value;
calculate an average electronic expansion valve position value based on the first electronic expansion valve position value and the second electronic expansion valve position value; and
control the electronic expansion valve to a position corresponding to the average electronic expansion valve position value for a predetermined amount of time.
2. The system of claim 1 , wherein the outdoor unit controller is further configured to:
retrieve a position of the electronic expansion valve corresponding to previous steady-state operation from a memory device; and
operate the electronic expansion valve at the retrieved position.
3. The system of claim 1 , wherein the outdoor unit controller is configured to control the electronic expansion valve according to a control loop feedback system, wherein the control loop feedback system is a proportional-integral-derivative algorithm.
4. The system of claim 1 , wherein the outdoor unit controller is configured to control the electronic expansion valve with a feedback control algorithm in response to a determination that the electronic expansion valve has been operated for at least a predefined amount of time at a predefined setting after being turned on.
5. The system of claim 4 , wherein the outdoor unit controller is configured to receive a current superheat value;
wherein the outdoor unit controller is configured to operate the electronic expansion valve with a feedback control algorithm in response to a determination that the current superheat value is less than a superheat setpoint.
6. The system of claim 1 , wherein the first electronic expansion valve position value is one of a plurality of electronic expansion valve position values;
wherein the second electronic expansion valve position value is a second one of the plurality of electronic expansion valve position values.
7. The system of claim 1 , wherein the outdoor unit controller is configured to determine the first electronic expansion valve position value by:
determining whether a first superheat value of a plurality of superheat values is a predefined amount less than a superheat setpoint;
determining whether a second superheat value of the plurality of superheat values is the predefined amount greater than the superheat setpoint after the first superheat value is the predefined amount less than the superheat setpoint; and
recording one of the plurality superheat values as the minimum superheat value in response to a determination that the first superheat value is the predefined amount less than the superheat setpoint and a determination that the second superheat value is the predefined amount greater than the superheat setpoint after the first superheat value is the predefined amount less than the superheat setpoint.
8. The system of claim 1 , wherein the outdoor unit controller is configured to determine the second electronic expansion valve position value by:
determining whether a first superheat value of a plurality of superheat values is a predefined amount greater than a superheat setpoint;
determining whether a second superheat value of the plurality of superheat values is the predefined amount less than the superheat setpoint after the first superheat value is the predefined amount greater than the superheat setpoint; and
recording one of the plurality superheat values as the maximum superheat value in response to a determination that the first superheat value is the predefined amount greater than the superheat setpoint and a determination that the second superheat value is the predefined amount less than the superheat setpoint after the first superheat value is the predefined amount greater than the superheat setpoint.