Electric Motor

• US 20140312745A1
• Filed: 02/12/2014
• Published: 10/23/2014
• Est. Priority Date: 08/12/2011
• Status: Abandoned Application

• Current Assignee: Aerovironment
• Original Assignee: Aerovironment
• Inventors: Nicoloff, William, Yu, QinZhong
• Application Number:
  US14/179,428
• Publication Number:
  US 20140312745A1
• Time in Patent Office: Days
• US Class Current: 310/67.R
• CPC Class Codes: H02K 1/17 Stator cores with permanent magnets
• CPC Class Codes: H02K 2213/03 Machines characterised by numerical values, ranges, mathematical expressions or similar information
• CPC Class Codes: H02K 29/03 with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
• CPC Class Codes: H02K 7/14 Structural association with mechanical loads, e.g. with hand-held machine tools or fans with fan or impeller for cooling the machine H02K9/06

Abstract

An asymmetric brushless direct current (DC) motor having a stator having a plurality of magnets and a rotor having a plurality of armatures where the vector sum of magnetic forces between each armature and each respective magnet is zero at every angular rotation position of the rotor with respect to the stator in the motor'"'"'s non-energized state.

Claims

1. A direct current (DC) motor apparatus, comprising:

a stator having a plurality of magnets; and

a rotor having a plurality of armatures, wherein a quantity of the plurality of armatures is less than a quantity of the plurality of magnets, each of the armatures of the plurality of armatures experiencing a vector magnetic force in response to its proximity to respective adjacent magnets of the plurality of magnets, and each of the armatures having a planar sidewall opposing a planar sidewall of an adjacent armature;

wherein the vector sum of magnetic forces between each armature and its respective adjacent magnets of the plurality of magnets is zero at every angular rotation position of the rotor with respect to the stator in the motor'"'"'s non-energized state.

2. The apparatus of claim 1, wherein each armature of the plurality of armatures comprises:

a forward-tapered end and an aft-tapered end, wherein each of the forward-tapered ends and each of the aft-tapered ends are configured to accept periodic near magnetic saturation as the armature rotates past the respective adjacent magnets of the plurality of magnets.

3. The apparatus of claim 2, wherein each armature of the plurality of armatures has a constant-radius face.

4. The apparatus of claim 3, wherein each magnet of the respective adjacent magnets of the plurality of magnets has a planar face in complementary opposition to the constant-radius face of each armature of the plurality of armatures.

5. The apparatus of claim 3, wherein the stator has between thirteen and nineteen magnets and the rotor has between twelve and eighteen armatures.

6. The apparatus of claim 2, wherein each armature of the plurality of armatures has a complementary face to each magnet of the respective adjacent magnets of the plurality of magnets, each complementary face selected from the group consisting of multi-planar, concave, and convex.

7. The apparatus of claim 2, wherein each armature of the plurality of armatures has a tapered root section.

8. The apparatus of claim 1, wherein the stator further comprises a back iron.

9. The apparatus of claim 8, wherein the back iron has inner angular sidewall portions to align each magnet of the plurality of magnets.

10. The apparatus of claim 1, wherein each magnet of the plurality of magnets is an electromagnet.

11. The apparatus of claim 1, wherein each armature of the plurality of armatures is comprised of alternating layers of a laminated electrical steel layer and an oxide film layer.

12. A DC motor apparatus, comprising:

a stator having a plurality of armatures, each of the armatures having a planar sidewall opposing a planar sidewall of an adjacent armature, and;

a rotor having a plurality of magnets, each of the magnets of the plurality of magnets experiencing a vector magnetic force in response to its proximity to respective adjacent armatures of the plurality of armatures, wherein a quantity of the plurality of magnets is less than a quantity of the plurality of armatures; and

wherein the vector sum of magnetic forces between each magnet and its respective adjacent armatures of the plurality of armatures is zero at every angular rotation position of rotor the with respect to the stator in the non-energized state of the motor.

13. The apparatus of claim 12, wherein each armature of the plurality of armatures comprises:

a forward-tapered end and an aft-tapered end, wherein each of the forward-tapered ends and each of the aft-tapered ends are configured to accept periodic near magnetic saturation as the magnets rotate past the respective adjacent armature of the plurality of armatures.

14. The apparatus of claim 13, wherein each armature of the plurality of armatures has a constant-radius face.

15. The apparatus of claim 14, wherein each magnet of the respective adjacent magnets of the plurality of magnets has a planar face in complementary opposition to the constant-radius face of each armature of the plurality of armatures.

16. The apparatus of claim 14, wherein the stator has between thirteen and nineteen armatures and the rotor has between twelve and eighteen magnets.

17. The apparatus of claim 13, wherein each armature of the plurality of armatures has a complementary face to each magnet of the respective adjacent magnets of the plurality of magnets, each complementary face selected from the group consisting of multi-planar, concave, and convex.

18. The apparatus of claim 13, wherein each armature of the plurality of armatures has a tapered root section.

19. The apparatus of claim 12, wherein the stator further comprises a back iron.

20. The apparatus of claim 19, wherein the back iron has inner angular sidewall portions to align each magnet of the plurality of magnets.

21. The apparatus of claim 12, wherein each magnet of the plurality of magnets is an electromagnet.

22. The apparatus of claim 12, wherein each armature of the plurality of armatures is comprised of alternating layers of a laminated electrical steel layer and an oxide film layer.

23. The apparatus of claim 12, further comprising:

a motor shaft driven by said rotor; and

a sensor rotatably driven by said motor shaft;

wherein the zero vector sum of magnetic forces between each magnet and its respective adjacent armatures results in a “

cogless”

rotation of the sensor on the motor shaft.

24. A method comprising:

communicating a plurality of magnetic fields between a respective plurality of armatures on a rotor and respective pairs of magnets on a stator for each armature; and

balancing the plurality of magnetic fields about the rotor as the rotor is rotated so that the vector sum of magnetic forces on the plurality of armatures is approximately zero as the rotor is rotated a complete revolution in its non-energized state;

wherein the motor is substantially “

cogless”

as the rotor turns in its non-energized state.

25. An unmanned aerial vehicle (UAV) sensor apparatus, comprising:

a UAV;

a brushless direct current (DC) motor coupled to the UAV, the DC motor further comprising;

a stator having a plurality of magnets; and

a rotor having a plurality of armatures, wherein a quantity of the plurality of armatures is less than a quantity of the plurality of magnets, each of the armatures of the plurality of armatures experiencing a vector magnetic force in response to its proximity to respective adjacent magnets of the plurality of magnets, and each of the armatures having a planar sidewall opposing a planar sidewall of an adjacent armature;

wherein the vector sum of magnetic forces between each armature and its respective adjacent magnets of the plurality of magnets is zero at every angular rotation position of the rotor with respect to the stator in the motor'"'"'s non-energized state; and

a sensor coupled to the motor in a direct-drive configuration;

wherein the sensor is driven directly by the motor so that an angular rotation of the rotatable shaft, Δ

φ

, results in the same angular rotation Δ

φ

of the sensor.

26. The apparatus of claim 25, wherein each armature of the plurality of armatures comprises:

a forward-tapered end and an aft-tapered end, wherein each of the forward-tapered ends and each of the aft-tapered ends are configured to accept periodic near magnetic saturation as the armature rotates past the respective adjacent magnets of the plurality of magnets.

27. The apparatus of claim 25, wherein each armature of the plurality of armatures has a face shape selected from the group consisting of multi-planar, concave, and convex.

28. An unmanned aerial vehicle (UAV) sensor apparatus, comprising:

a UAV;

a direct-drive motor coupled to the UAV; and

a sensor coupled to the direct-drive motor, the direct-drive motor configured to angularly drive the sensor.

29. The apparatus of claim 28, wherein the direct-drive motor is coupled to the UAV through a support.