Methods of magnetizing and controlling a variable-flux memory motor

1. A method for magnetizing a soft magnet in a rotor of a variable-flux memory motor (VFMM), the method comprising:

measuring a back electromotive force generated by the soft magnet;

determining a real-time magnetization state of the soft magnet based on the measured back electromotive force;

determining a first pulse based on a difference between an ideal magnetization state and the real-time magnetization state of the soft magnet,

wherein the first pulse has a duration of equal to or more than 0.1 millisecond (ms) and equal to or less than 2 ms; and

applying the first pulse to a stator winding of the VFMM to set a magnetization state of the soft magnet to a first magnetization state when the first pulse ends.

2. The method of claim 1 , wherein the duration of the first pulse is equal to or less than 1 ms.

3. The method of claim 1 , wherein the duration of the first pulse is equal or greater than 0.3 ms.

4. The method of claim 1 , wherein

the duration of the first pulse is less than 1 ms, and

one or more consecutive pulses with a duration of equal to or more than 0.3 ms and less than 1 ms magnetize the soft magnet.

5. The method of claim 1 , wherein

the duration of the first pulse is equal to or more than 1 ms, and

only the first pulse magnetizes the soft magnet.

6. The method of claim 1 , wherein the soft magnet is AlNiCo.

7. The method of claim 1 , wherein the soft magnet is AlNiCo-9.

8. The method of claim 1 , wherein a shape of the first pulse is triangular.

9. The method of claim 1 , further comprising:

generating a second pulse of electric current that has a duration of equal to or more than 0.1 ms and equal to or less than 2 ms; and

applying the second pulse to the stator winding of the VFMM to set the magnetization state of the soft magnet to a second magnetization state when the second pulse ends,

wherein the second magnetization state is higher than the first magnetization state.

10. The method of claim 1 , further comprising:

generating a plurality of consecutive pulses of electric current that each has a duration of equal to or more than 0.1 ms and equal to or less than 2 ms; and

applying the plurality of consecutive pulses to the stator winding of the VMM to set the magnetization state of the soft magnet to a target magnetization state when the plurality of consecutive pulses ends,

wherein the target magnetization state is higher than the first magnetization state.

11. A method of controlling the magnetization state of the soft magnet of the VFMM comprising the method according to claim 1 , the method of controlling the magnetization state of the soft magnet of the VFMM further comprising:

receiving a command to change the magnetization state of the soft magnet;

determining the ideal magnetization state of the soft magnet based on the command;

and

sending the first pulse to the stator winding of the VFMM to adjust the real-time magnetization state of the soft magnet to the first magnetization state such that an absolute value of the difference between the ideal magnetization state and the first magnetization state falls within a predetermined threshold.

12. A method of automatically controlling the magnetization state of the soft magnet of the VFMM comprising the method according to claim 1 , the method of automatically controlling the magnetization state of the soft magnet of the VFMM further comprising:

measuring a speed of the VFMM;

determining a requested torque of the VFMM;

determining the ideal magnetization state of the soft magnet based on the speed and the requested torque of the VFMM;

and

sending the first pulse to the stator winding of the VFMM to adjust the real-time magnetization state to the first magnetization state such that an absolute value of the difference between the ideal magnetization state and the first magnetization state falls within a predetermined threshold.

13. A method of magnetizing a soft magnet of a variable-flux memory motor (VFMM), the method comprising:

measuring a speed of the VFMM;

determining a requested torque of the VFMM;

determining an ideal magnetization state of the soft magnet based on the speed and the requested torque of the VFMM;

measuring a back electromotive force generated by the soft magnet;

determining a real-time magnetization state of the soft magnet based on the measured back electromotive force;

determining a first pulse based on a difference between the ideal magnetization state and the real-time magnetization state of the soft magnet; and

sending the first pulse to a stator winding of the VFMM to adjust the real-time magnetization state to a first magnetization state such that an absolute value of the difference between the ideal magnetization state and the first magnetization state falls within a predetermined threshold,

wherein the VFMM is magnetized to a level using pulses of durations of less than 5 millisecond (ms).

14. The method of claim 13 , wherein the soft magnet is AlNiCo.

15. The method of claim 13 , wherein the soft magnet is AlNiCo-9.

16. The method of claim 13 , wherein a shape of the first pulse is triangular.