Field weakening for BLDC stand mixer
A method for operating an appliance, such as a stand mixer appliance, is provided. In one example implementation, the method can include operating a motor of the stand mixer appliance in order to rotate a mixer shaft of the stand mixer appliance. The method can further include determining, via a controller of the stand mixer appliance, a difference between an operating parameter and an operating parameter threshold. The method can further include implementing, via the controller of the stand mixer appliance, a field-weakening operation to increase a speed of the motor based at least in part on the difference.
1. A method for operating a stand mixer appliance, the method comprising:
operating a motor of the stand mixer appliance in order to rotate a mixer shaft of the stand mixer appliance;
determining, via a controller of the stand mixer appliance, a difference between an operating parameter and an operating parameter threshold; and
implementing, via the controller of the stand mixer appliance, a field-weakening operation to increase a speed of the motor of the stand mixer appliance by adjusting a field-weakening current setpoint based at least in part on the difference between the operating parameter and the operating parameter threshold.
2. The method of claim 1 , wherein the field-weakening operation is configured to reduce the operating parameter by generating a stator flux in a stator of the motor.
3. The method of claim 1 , wherein implementing the field-weakening operation comprises:
determining, via the controller of the stand mixer appliance, the operating parameter exceeds the operating parameter threshold; and
responsive to determining the operating parameter exceeds the operating parameter threshold, adjusting, via the controller of the stand mixer appliance, the field-weakening current setpoint based at least in part on the difference between the operating parameter and the operating parameter threshold.
4. The method of claim 3 , wherein the field-weakening current setpoint comprises a negative d-axis current setpoint in a field-oriented control (FOC) scheme.
5. The method of claim 1 , wherein the motor is a brushless direct current (BLDC) motor.
6. The method of claim 1 , wherein:
the stand mixer appliance further comprises a motor drive; and
the operating parameter is a phase voltage of the motor drive.
7. The method of claim 6 , wherein the operating parameter threshold is based at least in part on a maximum phase voltage of the motor drive.
8. The method of claim 7 , wherein the operating parameter threshold is about ninety-five percent of the maximum phase voltage of the motor drive.
9. A motor assembly for a stand mixer, the motor assembly comprising:
a motor, the motor comprising at least a rotor;
a motor drive;
an inverter electrically coupled to an alternating current power supply and the motor;
a sensorless feedback system configured to obtain feedback measurements of one or more electrical characteristics from the motor; and
a controller operably coupled to the motor, the controller configured to:
operate the motor in order to rotate a mixer shaft of the stand mixer;
determine a difference between an operating parameter and an operating parameter threshold; and
implement a field-weakening operation to increase a speed of the motor of the stand mixer by adjusting a field-weakening current setpoint based at least in part on the difference between the operating parameter and the operating parameter threshold.
10. The motor assembly of claim 9 , wherein the motor is a brushless direct current (BLDC) motor.
11. The motor assembly of claim 9 , wherein the field-weakening current setpoint comprises a negative d-axis current setpoint in a field-oriented control (FOC) scheme.
12. The motor assembly of claim 9 , wherein the operating parameter threshold is based at least in part on a maximum phase voltage of the motor drive.
13. The motor assembly of claim 9 , wherein:
the motor further comprises a stator; and
the field-weakening operation comprises generating a stator flux based at least in part on a rotor flux; and
the stator flux generated in the field-weakening operation opposes the rotor flux.
14. A stand mixer appliance, comprising:
a base;
a head pivotally mounted to the base;
a motor disposed within the head;
a mixer shaft rotatably mounted on the head; and
a controller operably coupled to the motor, the controller configured to:
operate the motor in order to rotate the mixer shaft of the stand mixer;
determine a difference between an operating parameter and an operating parameter threshold; and
implement a field-weakening operation to increase a speed of the motor by adjusting a field-weakening current setpoint based at least in part on the difference between the operating parameter and the operating parameter threshold.
15. The stand mixer appliance of claim 14 , wherein the motor is a brushless direct current (BLDC) motor.
16. The stand mixer appliance of claim 14 , wherein the motor is a permanent magnet synchronous motor (PMSM).
17. The stand mixer appliance of claim 14 , wherein the field-weakening current setpoint comprises a negative d-axis current setpoint in a field-oriented control (FOC) scheme.
18. The stand mixer appliance of claim 14 , further comprising a motor drive, wherein the operating parameter is a phase voltage of the motor drive.
19. The stand mixer appliance of claim 18 , wherein the operating parameter threshold is based at least in part on a maximum phase voltage of the motor drive.