Single phase field oriented control for a linear compressor
A method for operating a linear compressor of an appliance, such as a refrigerator appliance, is provided. In one example implementation, the method can include operating a motor of the linear compressor in order to drive a rotor of the motor. The method can further include obtaining, via a controller of the linear compressor, one or more feedback measurements of one or more electrical characteristics of the motor. The method can further include controlling, based at least in part on the one or more feedback measurements, the motor of the linear compressor using a single-phase vector-like control scheme.
1. A method for operating a linear compressor of an appliance, the method comprising:
operating a motor of the linear compressor in order to drive a rotor of the motor,
obtaining, via a controller of the linear compressor, one or more feedback measurements of one or more electrical characteristics of the motor; and
controlling, based at least in part on the one or more feedback measurements, the motor of the linear compressor using a single-phase control scheme by:
adjusting, via the controller, a d-axis current setpoint based at least in part on the one or more feedback measurements;
adjusting, via the controller, a q-axis current setpoint based at least in part on the one or more feedback measurements; and
adjusting, via the controller, a DC current setpoint based at least in part on the one or more feedback measurements.
2. The method of claim 1 , wherein controlling the motor using the single-phase control scheme further comprises:
determining, via the controller, a target current trajectory;
determining, via the controller, a trajectory difference between the target current trajectory and the one or more feedback measurements; and
responsive to determining the trajectory difference, adjusting, via the controller, a voltage setpoint based at least in part on the trajectory difference.
3. The method of claim 1 , wherein controlling the motor using the single-phase control scheme further comprises:
determining, via the controller, a field-weakening current difference between the d-axis current setpoint and a d-axis current component of the feedback measurements;
determining, via the controller, a stroke current difference between the q-axis current setpoint and a q-axis current component of the feedback measurements; and
determining, via the controller, a capacity current difference between the DC current setpoint and a DC current component of the feedback measurements.
4. The method of claim 3 , wherein controlling the motor using the single-phase control scheme further comprises:
adjusting, via the controller, a d-axis voltage setpoint based at least in part on the field-weakening current difference;
adjusting, via the controller, a q-axis voltage setpoint based at least in part on the stroke current difference; and
adjusting, via the controller, a DC voltage setpoint based at least in part on the capacity current difference.
5. The method of claim 1 , wherein the one or more feedback measurements comprises measurements indicative of a phase angle of magnetic flux of the rotor.
6. The method of claim 5 , wherein the controller comprises a sensored feedback system, the sensored feedback system configured to obtain one or more feedback measurements of the one or more electrical characteristics of the motor.
7. The method of claim 5 , wherein the controller comprises a sensorless feedback system, the sensorless feedback system configured to obtain one or more feedback measurements of the one or more electrical characteristics of the motor.
8. The method of claim 7 , wherein the sensorless feedback system comprises a back-electromotive force (back-EMF) observer.
9. A linear compressor defining an axial direction and a vertical direction, the linear compressor for an appliance comprising:
a cylindrical casing defining a compressor chamber;
a piston positioned within the compressor chamber and being movable along the axial direction;
a motor operably coupled to the piston; and
a controller operably coupled to the motor, the controller configured to:
operate the motor in order to drive a rotor of the motor;
obtain one or more feedback measurements of one or more electrical characteristics of the motor, the one or more feedback measurements comprising measurement indicative of a phase angle of magnetic flux of the rotor; and
control the motor using a single-phase control scheme based at least in part on the one or more feedback measurements.
10. The linear compressor of claim 9 , wherein the controller is further configured to:
determine a target current trajectory;
determine a trajectory difference between the target current trajectory and the one or more feedback measurements; and
adjust a voltage setpoint based at least in part on the trajectory difference.
11. The linear compressor of claim 9 , wherein the controller is further configured to:
adjust a d-axis current setpoint based at least in part on the one or more feedback measurements;
adjust a q-axis current setpoint based at least in part on the one or more feedback measurements; and
adjust a DC current setpoint based at least in part on the one or more feedback measurements.
12. The linear compressor of claim 11 , wherein the controller is further configured to:
determine a field-weakening current difference between the d-axis current setpoint and a d-axis current component of the feedback measurements;
determine a stroke current difference between the q-axis current setpoint and a q-axis current component of the feedback measurements; and
determine a capacity current difference between the DC current setpoint and a DC current component of the feedback measurements.
13. The linear compressor of claim 12 , wherein the controller is further configured to:
adjust a d-axis voltage setpoint based at least in part on the field-weakening current difference;
adjust a q-axis voltage setpoint based at least in part on the stroke current difference; and
adjust a DC voltage setpoint based at least in part on the capacity current difference.
14. The linear compressor of claim 9 , wherein the piston is a reciprocating piston.
15. The linear compressor of claim 9 , wherein the motor is a single-phase linear motor.
16. The linear compressor of claim 9 , wherein the controller comprises a sensorless feedback system, the sensorless feedback system being configured to obtain the one or more feedback measurements of one or more electrical characteristics of the motor.
17. An appliance, comprising:
a cabinet defining an internal chamber;
a door rotatably mounted to the cabinet to provide selective access to the internal chamber;
a linear compressor, the linear compressor having a piston movable in a negative axial direction toward a compressor chamber and a positive axial direction away from the compressor chamber;
a motor operably coupled to the piston;
an inverter configured to supply a variable frequency waveform to the motor; and
a controller operably coupled to the motor, the controller configured to:
operate the motor in order to drive a rotor of the motor;
obtain one or more feedback measurements of one or more electrical characteristics of the motor;
determine a target current trajectory;
determine a trajectory difference between the target current trajectory and the one or more feedback measurements; and
adjust a voltage setpoint based at least in part on the one or more feedback measurements.
18. The appliance of claim 17 , wherein:
the piston is a reciprocating piston; and
the motor is a single-phase linear motor.
19. The appliance of claim 17 , wherein the appliance is a refrigerator appliance.