Rotary electric machine
In a rotor in which magnet slots arranged in a V shape so as to open toward the outer circumferential side and having permanent magnets inserted therein are formed in a two-layer structure in a radial direction, the magnet slots in each layer are composed of a pair of slots formed between a center bridge located at the center and respective ones of two radially-outer bridges located between the outer surface of the rotor and the respective slots. Of magnetic fluxes generated from the permanent magnets, magnetic fluxes excluding magnetic fluxes for magnetically saturating the bridges are defined as effective magnetic fluxes. The rotor is configured such that the effective magnetic flux generated from the permanent magnet on the radially outer side is not greater than half the effective magnetic flux generated from the permanent magnet on the radially inner side.
1. A rotary electric machine comprising:
a stator formed in a cylindrical shape, the stator having a plurality of teeth on an inner surface side thereof and having a coil wound through coil slots formed between the teeth adjacent to each other; and
a rotor formed in a columnar shape, an outer surface thereof being opposed to an inner surface of the stator with a gap therebetween, the rotor being rotatably provided around a rotation center axis, wherein
the rotor has magnet slots arranged in a V shape so as to open from the rotation center axis side toward an outer circumferential side such that the magnet slots are formed in a two-layer structure in a radial direction,
the magnet slots in each layer are composed of a pair of slots formed between a center bridge located at a center and respective ones of two radially-outer bridges located between the outer surface of the rotor and the respective slots, and a permanent magnet is inserted in each of the slots, and
where
in a first-layer permanent magnet which is the permanent magnet inserted in each of first-layer magnet slots which are the magnet slots on a radially outer side, a magnet width excluding a magnet width for magnetically saturating a first-layer center bridge which is the center bridge corresponding to the first-layer magnet slot and a magnet width for magnetically saturating a first-layer radially-outer bridge which is the radially-outer bridge corresponding to the first-layer magnet slot is defined as a first-layer effective magnet width, and a magnetic flux generated from the first-layer effective magnet width is defined as a first-layer effective magnetic flux, and
in a second-layer permanent magnet which is the permanent magnet inserted in each of second-layer magnet slots which are the magnet slots on a radially inner side, a magnet width excluding a magnet width for magnetically saturating a second-layer center bridge which is the center bridge corresponding to the second-layer magnet slot and a magnet width for magnetically saturating a second-layer radially-outer bridge which is the radially-outer bridge corresponding to the second-layer magnet slot is defined as a second-layer effective magnet width, and a magnetic flux generated from the second-layer effective magnet width is defined as a second-layer effective magnetic flux,
the first-layer effective magnetic flux is not greater than half the second-layer effective magnetic flux.
2. The rotary electric machine according to claim 1 , wherein
the following expression is satisfied:
W
1
-
a
×
B
s
B
m
1
-
b
2
×
B
s
B
m
1
≤
(
W
2
-
c
×
B
s
B
m
2
-
d
2
×
B
s
B
m
2
)
×
B
m
2
B
m
1
2
,
where W 1 is a magnet width of the first-layer permanent magnet inserted in one of the pair of slots composing the first-layer magnet slots, a is a width of the first-layer radially-outer bridge, b is a width of the first-layer center bridge, W 2 is a magnet width of the second-layer permanent magnet inserted in one of the pair of slots composing the second-layer magnet slots, c is a width of the second-layer radially-outer bridge, d is a width of the second-layer center bridge, B s is a saturation magnetic flux density of a rotor core forming the rotor, B m1 is a magnetic flux density of the first-layer permanent magnet, and B m2 is a magnetic flux density of the second-layer permanent magnet.
3. The rotary electric machine according to claim 2 , wherein
the following expression is satisfied:
W
2
2
+
c
2
×
B
s
B
m
2
-
d
4
×
B
s
B
m
2
<
L
×
B
s
B
m
2
,
where L is a shortest distance between the first-layer magnet slot and the second-layer magnet slot.
4. The rotary electric machine according to claim 3 , wherein
each of the first-layer permanent magnet and the second-layer permanent magnet is permanent magnets physically divided in a longitudinal direction of each magnet slot.
5. The rotary electric machine according to claim 3 , wherein
a magnetic flux density of the second-layer permanent magnet is greater than a magnetic flux density of the first-layer permanent magnet.
6. The rotary electric machine according to claim 2 , wherein
the following expression is satisfied:
0.45
≤
θ
m
1
θ
m
2
≤
0.62
(
120
deg
≤
θ
m
2
≤
140
deg
)
,
where θ m1 is a first-layer magnet pole arc angle which is an angle between a pair of lines connecting the rotation center axis and respective V-shape-inner-side corners of sides of the first-layer magnet slots that are in contact with the first-layer radially-outer bridges, and θ m2 is a second-layer magnet pole arc angle which is an angle between a pair of lines connecting the rotation center axis and respective V-shape-inner-side corners of sides of the second-layer magnet slots that are in contact with the second-layer radially-outer bridges.
7. The rotary electric machine according to claim 6 , wherein
each of the first-layer permanent magnet and the second-layer permanent magnet is permanent magnets physically divided in a longitudinal direction of each magnet slot.
8. The rotary electric machine according to claim 4 , wherein
a magnetic flux density of the second-layer permanent magnet is greater than a magnetic flux density of the first-layer permanent magnet.
9. The rotary electric machine according to claim 2 , wherein
arc angles of the teeth of the stator are set such that, when one of the teeth of the stator is located on an extension line of a line connecting the rotation center axis and a V-shape-inner-side corner of a side of the first-layer magnet slot that is in contact with the first-layer radially-outer bridge, another one of the teeth of the stator is located on an extension line of a line connecting the rotation center axis and a V-shape-inner-side corner of a side of the second-layer magnet slot that is in contact with the second-layer radially-outer bridge.
10. The rotary electric machine according to claim 9 , wherein
a number of slots per pole per phase of the stator is 2, and the stator has, at ends of the respective teeth, protruding brims so that widths of the teeth are expanded, and
the following expressions are satisfied:
θ s1 ≤θ m1 ≤θ s2 and θ s3 ≤θ m2 ≤θ s4 ,
where
θ m1 is a first-layer magnet pole arc angle which is an angle between a pair of lines connecting the rotation center axis and respective V-shape-inner-side corners of sides of the first-layer magnet slots that are in contact with the first-layer radially-outer bridges, in the rotor, and θ m2 is a second-layer magnet pole arc angle which is an angle between a pair of lines connecting the rotation center axis and respective V-shape-inner-side corners of sides of the second-layer magnet slots that are in contact with the second-layer radially-outer bridges, in the rotor,
θ s1 is an angle between lines connecting the rotation center axis and respective protrusion ends, of the brims of two teeth across one tooth, that are on the one tooth side, and θ s2 is an angle between lines connecting the rotation center axis and respective protrusion ends of the brims that are on sides far from the one tooth, and
θ s3 is an angle between lines connecting the rotation center axis and respective protrusion ends, of the brims of two teeth across three teeth centered at the one tooth, that are on the one tooth side, and θ s4 is an angle between lines connecting the rotation center axis and respective protrusion ends of the brims that are on sides far from the one tooth.
11. The rotary electric machine according to claim 10 , wherein
each of the first-layer permanent magnet and the second-layer permanent magnet is permanent magnets physically divided in a longitudinal direction of each magnet slot.
12. The rotary electric machine according to claim 10 , wherein
a magnetic flux density of the second-layer permanent magnet is greater than a magnetic flux density of the first-layer permanent magnet.
13. The rotary electric machine according to claim 9 , wherein
each of the first-layer permanent magnet and the second-layer permanent magnet is permanent magnets physically divided in a longitudinal direction of each magnet slot.
14. The rotary electric machine according to claim 9 , wherein
a magnetic flux density of the second-layer permanent magnet is greater than a magnetic flux density of the first-layer permanent magnet.
15. The rotary electric machine according to claim 2 , wherein
each of the first-layer permanent magnet and the second-layer permanent magnet is permanent magnets physically divided in a longitudinal direction of each magnet slot.
16. The rotary electric machine according to claim 2 , wherein
a magnetic flux density of the second-layer permanent magnet is greater than a magnetic flux density of the first-layer permanent magnet.
17. The rotary electric machine according to claim 1 , wherein
each of the first-layer permanent magnet and the second-layer permanent magnet is permanent magnets physically divided in a longitudinal direction of each magnet slot.
18. The rotary electric machine according to claim 17 , wherein
a magnetic flux density of the second-layer permanent magnet is greater than a magnetic flux density of the first-layer permanent magnet.
19. The rotary electric machine according to claim 1 , wherein
a magnetic flux density of the second-layer permanent magnet is greater than a magnetic flux density of the first-layer permanent magnet.