Permanent magnet dynamoelectric rotating machine and electric vehicle equipped with the same
First Claim
Patent Images
1. A permanent magnet electric machine comprising:
- a stator provided with windings thereon; and
a rotor disposed with an air gap between the stator and the rotor, and having a plurality of permanent magnets embedded along a circumference thereof, with spacing between adjacent magnets;
whereina circumferential extent of surfaces of the permanent magnets facing the stator is selected so that an induced voltage in the machine has a waveform which approximates a sinusoidal waveform; and
an angle θ
whose sides are radii of the rotor passing through opposite circumferential ends of a surface of each permanent magnet facing the stator satisfies one of the expressions;
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +α
,
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +β
;
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +γ
where n is a natural number, τ
s is a slot pitch of slots in the stator, α
is an angle formed by a tooth, of the stator, β
is an angle formed by a slot of the stator, and γ
is an angle formed by an opening of each slot.
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Abstract
A permanent magnet electric machine comprises a stator provided with windings and a rotor disposed with an air gap between the stator and the rotor. A plurality of permanent magnets are arranged along and fixed to the circumference of the rotor. The angular circumferential extent of a surface of each permanent magnet facing the stator is determined so that an induced voltage in the machine has a waveform that approximates a sinusoidal waveform, to suppress the peak of the induced voltage.
72 Citations
14 Claims
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1. A permanent magnet electric machine comprising:
-
a stator provided with windings thereon; and a rotor disposed with an air gap between the stator and the rotor, and having a plurality of permanent magnets embedded along a circumference thereof, with spacing between adjacent magnets;
whereina circumferential extent of surfaces of the permanent magnets facing the stator is selected so that an induced voltage in the machine has a waveform which approximates a sinusoidal waveform; and an angle θ
whose sides are radii of the rotor passing through opposite circumferential ends of a surface of each permanent magnet facing the stator satisfies one of the expressions;
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +α
,
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +β
;
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +γwhere n is a natural number, τ
s is a slot pitch of slots in the stator, α
is an angle formed by a tooth, of the stator, β
is an angle formed by a slot of the stator, and γ
is an angle formed by an opening of each slot.
-
-
2. A permanent magnet electric machine comprising:
-
a stator provided with windings thereon; and a rotor disposed with an air gap between the stator and the rotor, and having a plurality of permanent magnets embedded along a circumference thereof, with spacing between adjacent magnets;
whereina circumferential extent of surfaces of the permanent magnets facing the stator is selected so that an induced voltage in the machine has a waveform which approximates a sinusoidal waveform; each permanent magnet is partially embedded in a core of the rotor and has a portion which projects at least to the circumference of the rotor; and an angle θ
whose sides are radii of the rotor passing through opposite circumferential ends of said portion of each permanent magnet which projects at least to the circumference of the rotor satisfies the expression;
space="preserve" listing-type="equation">θ
≈
(n+0.5)×
τ
.sub.swhere n is a natural number and τ
s is a slot pitch of slots in the stator.
-
-
3. A permanent magnet electric machine comprising:
-
a stator provided with windings thereon; and a rotor disposed with an air cap between the stator and the rotor, and having a plurality of permanent magnets embedded along a circumference thereof, with spacing between adjacent magnets;
whereina circumferential extent of surfaces of the permanent magnets facing the stator is selected so that an induced voltage in the machine has a waveform which approximates a sinusoidal waveform; and an angle θ
whose sides are radii of the rotor passing through opposite circumferential ends of a surface of each permanent magnet facing the stator satisfies the expression;
space="preserve" listing-type="equation">θ
≈
(n+0.5)×
τ
.sub.swhere n is a natural number and τ
s is the pitch of slots in the stator.
-
-
4. A permanent magnet electric machine comprising:
-
a stator provided with windings thereon; and a rotor disposed with an air gap between the stator and the rotor, and having a plurality of permanent magnets embedded along a circumference thereof, with spacing between adjacent magnets;
whereina circumferential extent of surfaces of the permanent magnets facing the stator is selected so that an induced voltage in the machine has a waveform which approximates a sinusoidal waveform; the stator has forty-eight slots; the permanent magnets form eight poles; an angle whose sides are radii of the rotor passing through opposite circumferential ends of a surface of each permanent magnet which is nearer to the stator, is in the range of 26±
1°
measured in mechanical degrees; andan angle whose sides are radii of the rotor passing through opposite circumferential ends of a surface of each permanent magnet which is farther from the stator is in the range of 36+/-1°
measured in mechanical degrees.
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5. A permanent magnet electric motor comprising:
-
a stator having an electrical winding arranged in slots thereof; and a rotor which is rotatable within said stator and has a plurality of permanent magnets partially embedded in a core thereof and projecting at least to an outer circumference of said core, adjacent an inner circumference of said stator, whereby magnetic flux of said permanent magnets links said windings of said stator; wherein an angle θ
which defines a circumferential angular extent of a portion of each of said permanent magnets which projects at least to said outer circumference of said core satisfies the expression;
space="preserve" listing-type="equation">θ
≈
(n+0.5)×
τ
.sub.swhere n is an integer and τ
s is a slot pitch of the slots in said stator.
-
-
6. A permanent magnet electric motor comprising:
-
a stator having electrical windings arranged in slots thereof; and a rotor which is rotatable within said stator and has a plurality of permanent magnets embedded on an outer circumference thereof adjacent an inner circumference of said stator, whereby magnetic flux of said permanent magnets links said windings on said stator; wherein an angle θ
which defines a circumferential angular extent of a radially outer surface of each of said permanent magnets satisfies the expression;
space="preserve" listing-type="equation">θ
≈
(n+0.5)×
τ
.sub.swhere n is an integer and τ
s is a slot pitch of the slots in said stator. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A permanent magnet electric machine comprising:
-
a stator provided with windings thereon; and a rotor disposed with an air gap between the stator and the rotor, and having a plurality of permanent magnets fixed along a circumference thereof; wherein an angle θ
which defines an angular extent of an outer surface of each of said permanent magnets satisfies one of the expressions;
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +α
;
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +β
;
or
space="preserve" listing-type="equation">θ
≈
n×
τ
.sub.s +γwhere n is a natural number, τ
s is the pitch of slots in a slot stator, α
is an angle formed by a tooth of the stator, β
is an angle formed by a slot of the stator, and γ
is an angle formed by an opening of each slot. - View Dependent Claims (13, 14)
-
Specification