Expansion valve position detection in refrigeration system
A refrigerated display case having a housing defining a temperature controlled space and a refrigeration system coupled to the housing is provided. The refrigeration system is configured to be operable to affect a temperature of the temperature controlled space. The refrigeration system includes an actuator, a controller, and a sensor. The controller is configured to continuously update a stored position of the actuator based on measurement of an electric current provided to the actuator, retrieve the stored position after a power failure, and restart control based on the stored position of the actuator. The sensor is configured to communicate with the controller.
1 . A method of calibrating an expansion valve controller comprising:
providing a first signal to an actuator;
detecting an electrical current supplied to the actuator;
storing a value of the electrical current to a non-volatile memory;
determining a first position of the actuator based on the electrical current;
detecting a magnitude change in the electrical current provided to the actuator by detecting that the electrical current is increasing;
detecting at least one spike in the electrical current;
storing the at least one spike in the non-volatile memory;
determining that the electrical current is decreasing to a first threshold;
determining, based on the at least one spike, that the actuator is in a second position of a plurality of discrete positions; and
storing the second position in the non-volatile memory.
2 . The method of claim 1 , further comprising:
positioning, responsive to the first signal, the actuator in a third position of the plurality of positions;
verifying that the actuator is in the third position based on at least the electrical current; and
storing the third position to the non-volatile memory.
3 . The method of claim 2 , further comprising:
providing a second signal to the actuator, the second signal configured to facilitate moving the actuator from the third position to a fourth position of the plurality of positions;
verifying that the actuator is transitioning from the third position to the fourth position based on at least the electrical current;
detecting at least one current spike while the actuator is transitioning from the third position to the fourth position;
storing the at least one current spike in the non-volatile memory;
determining that the actuator is in the fourth position based on at least the electrical current; and
storing the fourth position to the non-volatile memory.
4 . The method of claim 1 , wherein detecting the electrical current supplied to the actuator comprises:
detecting a magnitude change in the electrical current provided to the actuator by detecting that the electrical current is decreasing;
determining that the actuator is in a fifth position of the plurality of discrete positions based on the electrical current decreasing; and
store the fifth position in the non-volatile memory.
5 . The method of claim 1 , further comprising:
detecting a power failure of the expansion valve controller,
detecting a restoration of power following the power failure;
retrieving, responsive to the restoration of power following the power failure, the stored first position and the stored second position from the non-volatile memory; and
resuming operation of the actuator based on the stored first position and the stored second position.
6 . The method of claim 1 , wherein detecting the magnitude change in the electrical current provided to the actuator by detecting that the electrical current is increasing comprises detecting the electrical current increasing from a value between 0 A and 2 A to a value about 5 A.
7 . The method of claim 1 , wherein detecting the magnitude change in the electrical current provided to the actuator by detecting that the electrical current is decreasing comprises detecting the electrical current decreasing from a value about 5 A to a value between 0 A and 2 A.
8 . The method of claim 7 , wherein detecting the electrical current decreasing from the value about 5 A to the value between 0 A and 2 A indicates the actuator has stopped moving.
9 . The method of claim 2 , wherein detecting the electrical current supplied to the actuator comprises:
detecting a magnitude change in the electrical current provided to the actuator by detecting that the electrical current is decreasing;
determining that the actuator is in a fifth position of the plurality of discrete positions based on the electrical current decreasing; and
store the fifth position in the non-volatile memory.
10 . The method of claim 2 , further comprising:
detecting a power failure of the expansion valve controller,
detecting a restoration of power following the power failure;
retrieving, responsive to the restoration of power following the power failure, the stored first position and the stored second position from the non-volatile memory; and
resuming operation of the actuator based on the stored first position and the stored second position.
11 . An apparatus comprising a non-transitory computer readable medium configured to store instructions executable by at least one hardware processors to perform operations for calibrating an expansion valve controller, the operations comprising:
providing a first signal to an actuator;
detecting an electrical current supplied to the actuator;
storing a value of the electrical current to a non-volatile memory;
determining a first position of the actuator based on the electrical current;
detecting a magnitude change in the electrical current provided to the actuator by detecting that the electrical current is increasing;
detecting at least one spike in the electrical current;
storing the at least one spike in the non-volatile memory;
determining that the electrical current is decreasing to a first threshold;
determining, based on the at least one spike, that the actuator is in a second position of a plurality of discrete positions; and
storing the second position in the non-volatile memory.
12 . The apparatus of claim 11 , wherein the operations comprise:
positioning, responsive to the first signal, the actuator in a third position of the plurality of positions;
verifying that the actuator is in the third position based on at least the electrical current; and
storing the third position to the non-volatile memory.
13 . The apparatus of claim 12 , wherein the operations comprise:
providing a second signal to the actuator, the second signal configured to facilitate moving the actuator from the third position to a fourth position of the plurality of positions;
verifying that the actuator is transitioning from the third position to the fourth position based on at least the electrical current;
detecting at least one current spike while the actuator is transitioning from the third position to the fourth position;
storing the at least one current spike in the non-volatile memory;
determining that the actuator is in the fourth position based on at least the electrical current; and
storing the fourth position to the non-volatile memory.
14 . The apparatus of claim 11 , wherein the operation of detecting the electrical current supplied to the actuator comprises:
detecting a magnitude change in the electrical current provided to the actuator by detecting that the electrical current is decreasing;
determining that the actuator is in a fifth position of the plurality of discrete positions based on the electrical current decreasing; and
store the fifth position in the non-volatile memory.
15 . The apparatus of claim 11 , wherein the operations comprise:
detecting a power failure of the expansion valve controller,
detecting a restoration of power following the power failure;
retrieving, responsive to the restoration of power following the power failure, the stored first position and the stored second position from the non-volatile memory; and
resuming operation of the actuator based on the stored first position and the stored second position.
16 . The apparatus of claim 11 , wherein the operation of detecting the magnitude change in the electrical current provided to the actuator by detecting that the electrical current is increasing comprises detecting the electrical current increasing from a value between 0 A and 2 A to a value about 5 A.
17 . The apparatus of claim 11 , wherein the operation of detecting the magnitude change in the electrical current provided to the actuator by detecting that the electrical current is decreasing comprises detecting the electrical current decreasing from a value about 5 A to a value between 0 A and 2 A.
18 . The apparatus of claim 17 , wherein the operations of detecting the electrical current decreasing from the value about 5 A to the value between 0 A and 2 A indicates the actuator has stopped moving.
19 . The apparatus of claim 12 , wherein the operation of detecting the electrical current supplied to the actuator comprises:
detecting a magnitude change in the electrical current provided to the actuator by detecting that the electrical current is decreasing;
determining that the actuator is in a fifth position of the plurality of discrete positions based on the electrical current decreasing; and
store the fifth position in the non-volatile memory.
20 . The apparatus of claim 12 , wherein the operations comprise:
detecting a power failure of the expansion valve controller,
detecting a restoration of power following the power failure;
retrieving, responsive to the restoration of power following the power failure, the stored first position and the stored second position from the non-volatile memory; and
resuming operation of the actuator based on the stored first position and the stored second position.