Electric motor with asymmetric design for improved operation

Patent metadata

Field	Value
Publication number	US-10218234-B2
Application number	US-201615367351-A
Country	US
Kind code	B2
Filing date	Dec 2, 2016
Priority date	Dec 2, 2016
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

An electric motor in which at least one of the rotor and the stator has an asymmetric design is disclosed. The electric motor is divided into a number of segments, where each segment has an equal number of windings and an equal number of poles. The physical construction of each pole within a segment is identical and the number of turns of each winding within a segment is identical. The asymmetry is formed by varying the physical construction of the either the rotor or the stator within one segment from the corresponding construction of the rotor or stator in the other segments. The asymmetries are designed to improve one or more operating characteristics such as sensorless performance, torque ripple, or cogging torque in the motor.

First claim

We claim:

1. A permanent magnet machine, comprising:
a stator in the permanent magnet machine having a plurality of windings, wherein each winding includes a plurality of turns of an electrical conductor;
a rotor in the permanent magnet machine having a plurality of poles, wherein each pole includes a magnetic structure operable to interact with a current conducted in the plurality of windings to cause rotation of the rotor;
a plurality of segments defined within the permanent magnet machine, wherein;
each of the plurality of segments is defined from a center axis of the permanent magnet machine to an outer periphery of the permanent magnet machine and spans an angular distance around the permanent magnet machine equal to an angular distance spanned by each of the other segments,
the plurality of windings in the stator are distributed within each of the plurality of segments such that an equal number of windings are located within each of the plurality of segments,
the plurality of poles in the rotor are distributed within each of the plurality of segments such that an equal number of poles are located within each of the plurality of segments,
each winding, selected from the equal number of windings located within one of the plurality of segments, has an equal number of turns as the other windings within the corresponding segment, and
a physical construction of each pole, selected from the equal number of poles located within one of the plurality of segments, is the same;

a first asymmetry located in the rotor, wherein the first asymmetry is defined by a first physical construction of each pole located in a first segment, the first segment selected from the plurality of segments, being different than a second physical construction of the poles in other segments selected from the plurality of segments; and
a second asymmetry located in the stator and within one of the plurality of segments of the permanent magnet motor.

2. The permanent magnet machine of claim 1 wherein a number of segments included in the plurality of segments is equal to a greatest common divisor between a number of slots and a number of poles in the permanent magnet machine.

3. The permanent magnet machine of claim 2 wherein:
a first distance is defined between a first pole and a second pole, wherein the first pole and the second pole are selected from the plurality of poles and the first pole and the second pole together define a pole pair,
a second distance is defined between the center axis of the permanent magnet machine and the pole pair,
the first distance and the second distance for each pole pair within each of the plurality of segments is the same, and
the first asymmetry is defined by at least one of the first distance and the second distance within the first segment being different than the first distance and the second distance within each of the other segments.

4. The permanent magnet machine of claim 2 wherein:
each of the plurality of poles includes a magnet spanning a distance around the rotor,
the distance for each of the plurality of poles within each of the plurality of segments is the same,
the first asymmetry is defined by the distance for each of the plurality of poles within the first segment being different than the distance for each of the plurality of poles within each of the other segments.

5. The permanent magnet machine of claim 3 wherein the pole pairs in each of the plurality of segments includes a primary magnetic structure and the first asymmetry is defined by a secondary magnetic structure included within at least one of the plurality of poles in the first segment.

6. The permanent magnet machine of claim 2 wherein:
the stator includes a plurality of slot openings,
each slot opening, selected from the plurality of slot openings, located within one of the plurality segments is identical,
each slot opening, selected from the plurality of slot openings, located within a second segment, the second segment selected from the plurality of segments, includes a difference from each slot opening in other segments than the second segment selected from the plurality of segments, and
the second asymmetry is defined by the difference in each slot opening in the second segment and each slot opening in the other segments.

7. The permanent magnet machine of claim 2 wherein:
each winding, selected from the plurality of windings, located within one of the plurality segments is identical,
each winding, selected from the plurality of windings, located within a second segment, selected from the plurality of segments, includes a difference from each winding, selected from the plurality of windings, located in other segments than the second segment, and
the second asymmetry is defined by the difference in each winding in the second segment and each winding in the other segments.

8. The permanent magnet machine of claim 7 wherein the second asymmetry is further defined by a first number of turns for each winding in the second segment being different than a second number of turns for each winding in the other segments.

9. A permanent magnet machine comprising:
a stator in the permanent magnet machine having a plurality of windings;
a rotor in the permanent magnet machine having a plurality of poles;
a plurality of segments defined within the permanent magnet machine, wherein:
a number of segments present in the permanent magnet machine is equal to a greatest common divisor between a number of slots in the stator and a number of poles in the rotor,
the plurality of windings in the stator are distributed within each of the plurality of segments such that an equal number of windings are located within each of the plurality of segments,
the plurality of poles in the rotor are distributed within each of the plurality of segments such that an equal number of poles are located within each of the plurality of segments,
each winding, selected from the equal number of windings located within one of the plurality of segments, is the same as the other windings within the corresponding segment, and
each of the poles, selected from the equal number of poles located within one of the plurality of segments, has a physical construction that is the same as the other poles within the corresponding segment;

a first asymmetry located in the rotor; and
a second asymmetry located in the stator, wherein:
each winding within a first segment, selected from the plurality of segments, includes a difference from each winding in other segments selected from the plurality of segments, and
the second asymmetry is defined by the difference in each winding within the first segment and each winding in the other segments.

10. The permanent magnet machine of claim 9 wherein:
each of the plurality of windings includes a number of turns,
the number of turns for each of the plurality windings located within one segment, selected from the plurality of segments, is the same, and
the second asymmetry is defined by a first number of turns provided for each winding in the first segment being different than a second number of turns provided for each winding in the other segments.

11. The permanent magnet machine of claim 10 , wherein the first asymmetry is defined by a first physical construction of each pole in a second segment, selected from the plurality of segments, being different than a second physical construction of each pole in segments other than the second segment.

12. The permanent magnet machine of claim 11 wherein:
a first distance is defined between a first pole and a second pole, wherein the first pole and the second pole are selected from the plurality of poles and

Assignees

• Rockwell Automation Tech Inc

Inventors

• Sun Xikai
• Wei Kun
• Sizov Gennadi
• Liu Jingbo

Classifications

• H02K1/276 Primary

  Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] · CPC title

• H02K1/08

  Salient poles · CPC title

• H02K1/2766

  having a flux concentration effect · CPC title

• H02K21/16 Primary

  having annular armature cores with salient poles (with homopolar co-operation H02K21/20) · CPC title