Cogging reduction in permanent magnet machines
First Claim
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1. A permanent magnet motor comprising:
- a rotor having a plurality of permanent magnets defining a plurality of poles, each pole having a leading edge and a trailing edge; and
a stator having a plurality of teeth that are generally parallel to the permanent magnets, wherein the number of teeth is an integer multiple of the number of poles, and wherein when the leading edge of each pole aligns with a stator tooth the trailing edge of that pole is generally not aligned with a stator tooth.
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Abstract
A permanent magnet motor having a rotor and a stator and configured such that when the leading edge of each pole of the rotor aligns with a stator tooth the trailing edge of that pole is generally not aligned with a stator tooth.
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Citations
25 Claims
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1. A permanent magnet motor comprising:
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a rotor having a plurality of permanent magnets defining a plurality of poles, each pole having a leading edge and a trailing edge; and
a stator having a plurality of teeth that are generally parallel to the permanent magnets, wherein the number of teeth is an integer multiple of the number of poles, and wherein when the leading edge of each pole aligns with a stator tooth the trailing edge of that pole is generally not aligned with a stator tooth. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An electric motor, comprising:
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a rotor having a plurality of poles defined by permanent magnets, each of the poles having a flux field with a first flux edge and a second flux edge; and
a stator having winding slots separated by respective teeth, the number of teeth being an integer multiple of the number of poles, wherein at least one flux edge does not generally align with a tooth at the same time that another flux edge generally aligns with a tooth. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An electric motor comprising:
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a rotor having a plurality of permanent magnets defining a plurality of poles, each pole having a leading edge and a trailing edge, wherein the rotor is configured to rotate about a rotor axis of rotation; and
a stator having a plurality of teeth that are generally parallel to the rotor axis of rotation, wherein the number of teeth is an integer multiple of the number of poles, and wherein adjacent teeth are angularly spaced from one another by a predetermined pitch, and wherein the leading edge and the trailing edge of each pole are radially spaced from one another by an angle that is not an integer multiple of the pitch of the teeth. - View Dependent Claims (17, 18, 19, 20)
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21. A permanent magnet motor comprising:
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a rotor having a plurality of permanent magnets defining a plurality of poles, each pole having a leading edge and a trailing edge; and
a stator having a plurality of teeth that are generally parallel to the permanent magnets, wherein the number of teeth is an integer multiple of the number of poles, and wherein the leading and trailing edges of each pole are angularly disposed with respect to the stator teeth to reduce cogging torque.
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22. A method, comprising:
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providing a stator having a plurality of teeth separated by winding slots, wherein each tooth and an adjacent winding slot defines one tooth pitch; and
providing a rotor having a plurality of poles extending generally parallel to the teeth, each pole having a pole width, wherein the smallest difference in size between at least one pole width and an integer multiple of the tooth pitch is greater than 10% of the tooth pitch. - View Dependent Claims (23, 24, 25)
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Specification