Methods and apparatuses for fault management in permanent magnet synchronous machines using the field reconstruction method

1. A method for detecting faults and optimizing phase currents in an electromechanical energy converter, the method comprising:

measuring a current of a phase of the electromechanical energy converter;

modeling the electromechanical energy converter with the current measurement input into a field reconstruction module;

calculating a flux linkage of the electromechanical energy converter;

comparing the flux linkage with a flux linkage from a no fault electromechanical energy converter; and

optimizing the current of the phase of the electromechanical energy converter in response to the comparison.

2. The method of claim 1 , further comprising simultaneously detecting faults and optimizing phase currents in all the phases of the electromechanical energy converter.

3. The method of claim 1 , wherein the electromechanical energy converter comprises a permanent magnet synchronous machine.

4. The method of claim 3 , wherein calculating the flux linkage of the electromechanical energy converter comprises:

finding magnetic field components due to the permanent magnets and the stator excitation in the middle of the airgap of the permanent magnet synchronous machine; and

finding the contribution of the magnetic field components passing through the stator tooth of the permanent magnet synchronous machine.

5. The method of claim 4 , wherein finding the contribution of the magnetic field components passing through the stator tooth of the permanent magnet synchronous machine is calculated according to the equation of:

B

proj

⁡

(

j

)

=

∑

i

=

1

K

⁢

{

B

n

,

i

⁢

cos

⁡

(

ϕ

i

-

θ

j

)

-

B

t

,

i

⁢

sin

⁡

(

ϕ

i

-

θ

j

)

}

where B proj (j) is the projected field contribution of the magnetic field components passing through the stator tooth; B n,i is the normal component of the magnetic field density; B t,i is the tangential component of the magnetic field density; φ i are the positions of the field components in the air gap; i=1 . . . K is the number of field components solutions in the airgap covering one stator tooth; φ j are the positions of the magnetic field projection axes; and j is the respective stator tooth order.

6. The method of claim 3 , wherein modeling the electromechanical energy converter with the current measurement input into a field reconstruction module comprises:

obtaining a normal flux density distribution at a rotor position due to the permanent magnet of the permanent magnet synchronous machine;

obtaining a tangential flux density distribution at the rotor position due to the permanent magnet of the permanent magnet synchronous machine;

reconstructing a flux density due to all the phases of the permanent magnet synchronous machine;

reconstructing the flux density in a layer of interest; and

repeating the modeling for all positions of the rotor of the permanent magnet synchronous machine.

7. The method of claim 1 , wherein optimizing the current of the phase of the electromechanical energy converter in response to the comparison comprises maximizing average torque, maximizing average torque with minimum torque ripple, or minimizing torque ripple.

8. An apparatus for detecting faults and optimizing phase currents in an electromechanical energy converter, the apparatus comprising:

one or more processors; and

one or more memory units coupled to the processors,

the apparatus being configured to:

measure a current of a phase of the electromechanical energy converter;

model the electromechanical energy converter with the current measurement input into a field reconstruction module;

calculate a flux linkage of the electromechanical energy converter;

compare the flux linkage with a flux linkage from a no fault electromechanical energy converter; and

optimize the current of the phase of the electromechanical energy converter in response to the comparison.

9. The apparatus of claim 8 , wherein the apparatus is further configured to simultaneously detect faults and optimize phase currents in all the phases of the electromechanical energy converter.

10. The apparatus of claim 8 , wherein the electromechanical energy converter comprises a permanent magnet synchronous machine.

11. The apparatus of claim 10 , wherein the apparatus being configured to calculate the flux linkage of the electromechanical energy converter comprises:

finding magnetic field components due to the permanent magnets and the stator excitation in the middle of the airgap of the permanent magnet synchronous machine; and

finding the contribution of the magnetic field components passing through the stator tooth of the permanent magnet synchronous machine.

12. The apparatus of claim 11 , wherein finding the contribution of the magnetic field components passing through the stator tooth of the permanent magnet synchronous machine is calculated according to the equation of:

B

proj

⁡

(

j

)

=

∑

i

=

1

K

⁢

{

B

n

,

i

⁢

cos

⁡

(

ϕ

i

-

θ

j

)

-

B

t

,

i

⁢

sin

⁡

(

ϕ

i

-

θ

j

)

}

where B proj (j) is the projected field contribution of the magnetic field components passing through the stator tooth; B n,i is the normal component of the magnetic field density; B t,i the tangential component of the magnetic field density; φ i are the positions of the field components in the air gap; i=1 . . . K is the number of field components solutions in the airgap covering one stator tooth; θ j are the positions of the magnetic field projection axes; and j is the respective stator tooth order.

13. The apparatus of claim 10 , wherein the apparatus being configured to model the electromechanical energy converter with the current measurement input into a field reconstruction module comprises:

obtaining a normal flux density distribution at a rotor position due to the permanent magnet of the permanent magnet synchronous machine;

obtaining a tangential flux density distribution at the rotor position due to the permanent magnet of the permanent magnet synchronous machine;

reconstructing a flux density due to all the phases of the permanent magnet synchronous machine;

reconstructing the flux density in a layer of interest; and

repeating the modeling for all positions of the rotor of the permanent magnet synchronous machine.

14. The apparatus of claim 8 , wherein the apparatus being configured to optimize the current of the phase of the electromechanical energy converter in response to the comparison comprises maximizing average torque, maximizing average torque with minimum torque ripple, or minimizing torque ripple.