Axial gap electric machine with permanent magnets arranged between posts
An electric machine has a stator having an array of electromagnetic elements. A rotor is mounted on bearings and has an array of rotor posts. The rotor posts each have a length defining opposed ends and the array of rotor posts extends along the rotor in a direction perpendicular to the length of each of the rotor posts. The rotor has electromagnetic elements defining magnetic poles placed between the plurality of rotor posts. An airgap is formed between the rotor and the stator when they are in an operational position. A plurality of rotor flux restrictors are formed on the rotor, and each lies adjacent to one of the opposed ends of the rotor posts.
1. An electric machine comprising:
a stator having an array of electromagnetic elements;
a rotor mounted on a first bearing comprising an inner thrust bearing and a second bearing comprising an outer thrust bearing, the rotor having an array of rotor posts, each of the rotor posts having a length defining opposed ends and the array of rotor posts extending along the rotor in a direction perpendicular to the length of each of the rotor posts, and the rotor having electromagnetic elements arranged radially inward of the outer thrust bearing and radially outward of the inner thrust bearing defining magnetic poles placed between the plurality of rotor posts;
an airgap being formed axially between the rotor and the stator when the stator and the rotor are in an operational position; and
a plurality of rotor flux restrictors being formed on the rotor, each of the plurality of rotor flux restrictors each lying adjacent to one of the opposed ends of the rotor posts,
wherein the flux restrictors comprise a plurality of inner flux restrictors lying radially inward from the rotor posts and radially outward from the inner thrust bearing and further comprises a plurality of outer flux restrictors lying radially outward from the rotor posts and radially inward from the outer thrust bearings.
2. The electric machine of claim 1 in which the bearings further comprise:
a first bearing connecting the rotor and the stator, the first bearing being arranged to allow relative rotary motion of the rotor and the stator;
a second bearing connecting the rotor and the stator, the second bearing being arranged to allow relative rotary motion of the rotor and the stator; and
in which the array of rotor posts and the plurality of rotor flux restrictors lie on the rotor between the first bearing and the second bearing.
3. The electric machine of claim 2 in which the plurality of rotor flux restrictors further comprises a plurality of holes within the rotor.
4. The electric machine of claim 3 in which the plurality of rotor flux restrictors further comprises a plurality of blind holes.
5. The electric machine of claim 3 in which the plurality of rotor flux restrictors further comprises a plurality of through holes.
6. The electric machine of claim 2 in which:
the electric machine further comprises an axial electric machine,
the first bearing further comprises an inner thrust bearing,
the second bearing further comprises an outer thrust bearing, and
the electromagnetic elements of the stator and the electromagnetic elements of the rotor are arranged radially inward of the outer thrust bearing and radially outward of the inner thrust bearing, the inner thrust bearing and the outer thrust bearing being arranged to maintain the airgap against a magnetic attraction of the electromagnetic elements of the rotor and the electromagnetic elements of the stator.
7. The electric machine of claim 1 in which the each of the inner and outer flux restrictors are radially aligned in an alternating pattern relative to the rotor posts, so that the inner and outer flux restrictors are adjacent to every second rotor post.
8. The electric machine of claim 7 in which the inner and outer flux restrictors are adjacent to alternate rotor posts so that each rotor post is adjacent to only one of the inner flux restrictors or one of the outer flux restrictors.
9. The electric machine of claim 1 in which each of the inner and outer flux restrictors are radially aligned with the rotor posts, and the inner and outer flux restrictors are adjacent to each rotor post.
10. The electric machine of claim 1 in which for each rotor posts, the rotor post is adjacent to two inner flux restrictors and two outer flux restrictors.
11. The electric machine of claim 1 in which the plurality of inner flux restrictors and the plurality of outer flux restrictors each further comprise a plurality of holes having the same geometry.
12. The electric machine of claim 11 in which the plurality of holes having the same geometry further comprise a plurality of holes having a circular cross-section.
13. The electric machine of claim 12 in which the circular cross-section of each of the plurality of holes has an equal size.
14. The electric machine of any of claim 1 in which the stator further comprises stator posts that form the electromagnetic elements of the stator, with slots between the stator posts, one or more electric conductors in each slot, each of the stator posts having a length defining opposed ends and the array of stator posts extending around the stator circularly in a direction perpendicular to the length of each of the posts and the stator further comprising a plurality of stator flux restrictors being formed on the stator, each of the plurality of stator flux restrictors lying adjacent to one of the opposed ends of the stator posts.
15. The electric machine of claim 1 in which the stator further comprises stator posts that form the electromagnetic elements of the stator, with slots between the stator posts, one or more electric conductors in each slot, the posts of the stator having a post height in mm, the stator and rotor together defining a size of the electric machine, the magnetic poles have a pole pitch S in mm, the size of the electric machine, pole pitch and post height being selected to fall within a region in a space defined by size, pole pitch and post height, the region being defined by either
1) a first union of:
a) a first surface defined by a first set of inequalities for a first size of electric machine;
b) a second surface defined by a second set of inequalities for a second size of electric machine; and
c) a set defined as containing all points lying on line segments having a first end point on the first surface and a second end point on the second surface;
the first set of inequalities and the second set of inequalities being respectively sets of inequalities A and B, or B and C, or C and D, in which the group of inequalities A is for a size of 25 mm, the group of inequalities B is for a size of 50 mm, the group of inequalities C is for a size of 100 mm, the group of inequalities D is for a size of 200 mm; or
2) a second union of a surface as defined by set of inequalities D and a corresponding set of all points with size greater than the surface but with pole pitch and post height corresponding to points within the surface;
where
A is selected from the group of sets of inequalities consisting of:
Set A1:
Post Height>
−1.070 * S + 2.002
for
0.572 < S < 1.189
1.175 * S + −0.667
for
1.189 < S < 2.269
13.502 * S − 28.637
for
2.269 < S < 2.500
Post Height<
−5.898 * S + 19.863
for
1.970 < S < 2.500
0.229 * S + 7.794
for
1.349 < S < 1.970
7.607 * S − 2.160
for
0.723 < S < 1.349
11.430 * S − 4.924
for
0.572 < S < 0.723
Set A2:
Post Height>
−1.340 * S + 2.305
for
0.619 < S < 1.120
1.100 * S − 0.429
for
1.120 < S < 2.074
3.830 * S − 6.082
for
2.074 < S < 2.269
Post Height<
−69.510 * S + 160.318
for
2.222 < S < 2.269
−3.430 * S + 13.492
for
1.667 < S < 2.222
2.830 * S + 3.056
for
1.133 < S < 1.667
8.650 * S − 3.545
for
0.619 < S < 1.133
Set A3:
Post Height>
−4.160 * S + 5.032
for
0.723 < S < 0.967
0.839 * S + 0.198
for
0.967 < S < 1.692
2.713 * S − 2.973
for
1.692 < S < 1.939
Post Height<
−53.233 * S + 105.506
for
1.879 < S < 1.939
−1.406 * S + 8.122
for
1.465 < S < 1.879
3.898 * S + 0.353
for
1.035 < S < 1.465
7.535 * S − 3.412
for
0.723 < S < 1.035
B is selected from the group of sets of inequalities consisting of:
Set B1:
Post Height>
0.254 * S + 0.462
for
0.319 < S < 3.667
2.665 * S + −8.380
for
3.667 < S < 5.000
Post Height<
−18.282 * S + 96.357
for
4.500 < S < 5.000
−4.663 * S + 35.071
for
2.738 < S < 4.500
2.585 * S + 15.227
for
1.447 < S < 2.738
16.013 * S − 4.204
for
0.319 < S < 1.447
Set B2:
Post Height>
0.269 * S + 0.456
for
0.380 < S < 3.016
3.051 * S − 7.936
for
3.016 < S < 4.167
Post Height<
−14.766 * S + 66.309
for
3.667 < S < 4.167
−3.952 * S + 26.654
for
2.315 < S < 3.667
3.108 * S + 10.310
for
1.278 < S < 2.315
14.542 * S − 4.303
for
0.389 < S < 1.278
88.444 * S − 33.051
for
0.380 < S < 0.389
Set B3:
Post Height>
0.191 * S + 0.626
for
0.472 < S < 2.181
2.135 * S − 3.613
for
2.181 < S < 3.095
53.475 * S − 162.511
for
3.095 < S < 3.175
Post Height<
−5.095 * S + 23.450
for
2.222 < S < 3.175
0.805 * S + 10.339
for
1.381 < S < 2.222
10.251 * S − 2.706
for
0.572 < S < 1.381
24.420 * S − 10.810
for
0.472 < S < 0.572
C is selected from the group of sets of inequalities consisting of:
Set C1:
Post Height>
0.322 * S + 0.359
for
0.233 < S < 6.667
2.202 * S − 12.179
for
6.667 < S < 8.333
Post Height<
−25.555 * S + 219.122
for
7.778 < S < 8.333
−5.585 * S + 63.794
for
4.000 < S < 7.778
3.214 * S + 28.600
for
1.793 < S < 4.000
21.749 * S − 4.633
for
0.233 < S < 1.793
Set C2:
Post Height>
0.277 * S + 0.593
for
0.250 < S < 5.182
2.342 * S − 10.111
for
5.182 < S < 7.222
Post Height<
−13.149 * S + 101.763
for
6.111 < S < 7.222
−4.885 * S + 51.265
for
3.333 < S < 6.111
4.291 * S + 20.680
for
1.520 < S < 3.333
20.788 * S − 4.395
for
0.251 < S < 1.520
161.000 * S − 39.588
for
0.250 < S < 0.251
Set C3:
Post Height>
0.277 * S + 0.591
for
0.278 < S < 4.425
1.916 * S − 6.663
for
4.425 < S < 6.111
Post Height<
−21.337 * S + 135.438
for
5.556 < S < 6.111
−4.985 * S + 44.588
for
3.175 < S < 5.556
2.749 * S + 20.031
for
1.560 < S < 3.175
18.321 * S − 4.260
for
0.278 < S < 1.560
and
D is selected from the group of sets of inequalities consisting of:
Set D1:
Post Height>
0.257 * S + 0.327
for
0.208 < S < 7.778
1.977 * S − 13.044
for
7.778 < S < 9.444
Post Height<
−36.195 * S + 347.445
for
8.889 < S < 9.444
−5.777 * S + 77.062
for
4.833 < S < 8.889
1.950 * S + 39.718
for
2.222 < S < 4.833
20.301 * S + −1.058
for
0.389 < S < 2.222
34.481 * S + −6.574
for
0.208 < S < 0.389
Set D2:
Post Height>
0.322 * S + 0.359
for
0.233 < S < 6.667
2.202 * S + −12.179
for
6.667 < S < 8.333
Post Height<
−25.555 * S + 219.122
for
7.778 < S < 8.333
−5.585 * S + 63.794
for
4.000 < S < 7.778
3.214 * S + 28.600
for
1.793 < S < 4.000
21.749 * S + −4.633
for
0.233 < S < 1.793
Set D3:
Post Height>
0.212 * S + 0.600
for
0.264 < S < 4.833
3.017 * S + −12.960
for
4.833 < S < 6.667
Post Height<
−12.356 * S + 89.531
for
5.556 < S < 6.667
−4.551 * S + 46.170
for
3.175 < S < 5.556
3.850 * S + 19.496
for
1.502 < S < 3.175
19.751 * S + −4.387
for
0.264 < S < 1.502
16. An electric machine comprising:
a stator having an array of electromagnetic elements;
a rotor mounted on bearings, the rotor having an array of rotor posts, each of the rotor posts having a length defining opposed ends and the array of rotor posts extending along the rotor in a direction perpendicular to the length of each of the rotor posts, and the rotor having electromagnetic elements defining magnetic poles placed between the plurality of rotor posts;
an airgap being formed between the rotor and the stator when the stator and the rotor are in an operational position; and
a plurality of rotor flux restrictors being formed on the rotor, each of the plurality of rotor flux restrictors each lying adjacent to one of the opposed ends of the rotor posts,
wherein the stator further comprises stator posts that form the electromagnetic elements of the stator, with slots between the stator posts, one or more electric conductors in each slot, the posts of the stator having a post height in mm, the stator and rotor together defining a size of the electric machine, the magnetic poles have a pole pitch S in mm, the size of the electric machine, pole pitch and post height being selected to fall within a region in a space defined by size, pole pitch and post height, the region being defined by either
1) a first union of:
a) a first surface defined by a first set of inequalities for a first size of electric machine;
b) a second surface defined by a second set of inequalities for a second size of electric machine; and
c) a set defined as containing all points lying on line segments having a first end point on the first surface and a second end point on the second surface;
the first set of inequalities and the second set of inequalities being respectively sets of inequalities A and B, or B and C, or C and D, in which the group of inequalities A is for a size of 25 mm, the group of inequalities B is for a size of 50 mm, the group of inequalities C is for a size of 100 mm, the group of inequalities D is for a size of 200 mm; or
2) a second union of a surface as defined by set of inequalities D and a corresponding set of all points with size greater than the surface but with pole pitch and post height corresponding to points within the surface;
where
A is selected from the group of sets of inequalities consisting of:
Set A1:
Post Height >
−1.070 * S + 2.002
for
0.572 < S < 1.189
1.175 * S + −0.667
for
1.189 < S < 2.269
13.502 * S − 28.637
for
2.269 < S < 2.500
Post Height <
−5.898 * S + 19.863
for
1.970 < S < 2.500
0.229 * S + 7.794
for
1.349 < S < 1.970
7.607 * S − 2.160
for
0.723 < S < 1.349
11.430 * S − 4.924
for
0.572 < S < 0.723
Set A2:
Post Height >
−1.340 * S + 302.305
for
0.619 < S < 1.120
1.100 * S − 0.429
for
1.120 < S < 2.074
3.830 * S − 6.082
for
2.074 < S < 2.269
Post Height <
−69.510 * S + 160.318
for
2.222 < S < 2.269
−3.430 * S + 13.492
for
1.667 < S < 2.222
2.830 * S + 3.056
for
1.133 < S < 1.667
8.650 * S − 3.545
for
0.619 < S < 1.133
Set A3:
Post Height >
−4.160 * S + 5.032
for
0.723 < S < 0.967
0.839 * S + 0.198
for
0.967 < S < 1.692
2.713 * S − 2.973
for
1.692 < S < 1.939
Post Height <
−53.233 * S + 105.506
for
1.879 < S < 1.939
−1.406 * S + 8.122
for
1.465 < S < 1.879
3.898 * S + 0.353
for
1.035 < S < 1.465
7.535 * S − 3.412
for
0.723 < S < 1.035
B is selected from the group of sets of inequalities consisting of:
Set B1:
Post Height >
0.254 * S + 0.462
for
0.319 < S < 3.667
2.665 * S + −8.380
for
3.667 < S < 5.000
Post Height <
−18.282 * S + 96.357
for
4.500 < S < 5.000
−4.663 * S + 35.071
for
2.738 < S < 4.500
2.585 * S + 15.227
for
1.447 < S < 2.738
16.013 * S − 4.204
for
0.319 < S < 1.447
Set B2:
Post Height >
0.269 * S + 0.456
for
0.380 < S < 3.016
3.051 * S − 7.936
for
3.016 < S < 4.167
Post Height <
−14.766 * S + 66.309
for
3.667 < S < 4.167
−3.952 * S + 26.654
for
2.315 < S < 3.667
3.108 * S + 10.310
for
1.278 < S < 2.315
14.542 * S − 4.303
for
0.389 < S < 1.278
88.444 * S − 33.051
for
0.380 < S < 0.389
Set B3:
Post Height >
0.191 * S + 0.626
for
0.472 < S < 2.181
2.135 * S − 3.613
for
2.181 < S < 3.095
53.475 * S − 162.511
for
3.095 < S < 3.175
Post Height <
−5.095 * S + 23.450
for
2.222 < S < 3.175
0.805 * S + 10.339
for
1.381 < S < 2.222
10.251 * S − 2.706
for
0.572 < S < 1.381
24.420 * S − 10.810
for
0.472 < S < 0.572
C is selected from the group of sets of inequalities consisting of:
Set C1:
Post Height >
0.322 * S + 0.359
for
0.233 < S < 6.667
2.202 * S − 12.179
for
6.667 < S < 8.333
Post Height <
−25.555 * S + 219.122
for
7.778 < S < 8.333
−5.585 * S + 63.794
for
4.000 < S < 7.778
3.214 * S + 28.600
for
1.793 < S < 4.000
21.749 * S − 4.633
for
0.233 < S < 1.793
Set C2:
Post Height <
0.277 * S + 0.593
for
0.250 < S < 5.182
2.342 * S − 10.111
for
5.182 < S < 7.222
Post Height >
−13.149 * S + 101.763
for
6.111 < S < 7.222
−4.885 * S + 51.265
for
3.333 < S < 6.111
4.291 * S + 20.680
for
1.520 < S < 3.333
20.788 * S − 4.395
for
0.251 < S < 1.520
161.000 * S − 39.588
for
0.250 < S < 0.251
Set C3:
Post Height <
0.277 * S + 0.591
for
0.278 < S < 4.425
1.916 * S − 6.663
for
4.425 < S < 6.111
Post Height >
−21.337 * S + 135.438
for
5.556 < S < 6.111
−4.985 * S + 44.588
for
3.175 < S < 5.556
2.749 * S + 20.031
for
1.560 < S < 3.175
18.321 * S − 4.260
for
0.278 < S < 1.560
and
D is selected from the group of sets of inequalities consisting of:
Set D1:
Post Height <
0.257 * S + 0.327
for
0.208 < S < 7.778
1.977 * S − 13.044
for
7.778 < S < 9.444
Post Height >
−36.195 * S + 47.445
for
8.889 < S < 9.444
−5.777 * S + 77.062
for
4.833 < S < 8.889
1.950 * S + 39.718
for
2.222 < S < 4.833
20.301 * S + −1.058
for
0.389 < S < 2.222
34.481 * S + −6.574
for
0.208 < S < 0.389
Set D2:
Post Height <
0.322 * S + 0.359
for
0.233 < S < 6.667
2.202 * S + −12.179
for
6.667 < S < 8.333
Post Height >
−25.555 * S + 219.122
for
7.778 < S < 8.333
−5.585 * S + 63.794
for
4.000 < S < 7.778
3.214 * S + 28.600
for
1.793 < S < 4.000
21.749 * S + −4.633
for
0.233 < S < 1.793
Set D3:
Post Height <
0.212 * S + 0.600
for
0.264 < S < 4.833
3.017 * S + −12.960
for
4.833 < S < 6.667
Post Height >
−12.356 * S + 89.531
for
5.556 < S < 6.667
−4.551 * S + 46.170
for
3.175 < S < 5.556
3.850 * S + 19.496
for
1.502 < S < 3.175
19.751 * S + −4.387
for
0.264 < S < 1.502