Electric machine

1. An electric machine having a sator and rotor, the stator comprising;

circumferentially spaced posts defining slots between the posts,

conductive elements arranged around the posts, and

each conductive element defining a respective electrical flow path that extends through a respective selection of the slots in order of circumferential arrangement of the slots of the respective selection of the slots, the respective selection of the slots either being consecutive slots of the stator or not being consecutive slots of the stator, and extending in alternating opposition directions through successive slots of the respective selection of slots;

in which the posts have a post height in mm, and the electric machine firther comprising:

the rotor having electricmagnetic element definging magnetic poles, the rotor being arranged to move relative to the sator;

an airgap between the stator and the rotor;

the stator and the rotor together defining a size of the electric machine;

the magnetic poles having 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 set of inequalities A is for a size of 25mm , the set of inequalities B is for a size of 50 mm, the set of inequalities C is for a size of 100mm, the set 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.

2. The electric machine of claim 1 in which the respective selections of slots each consist of consecutive slots in a respective sector of the stator.

3. The electric machine of claim 1 in which the for at least some of the conductive elements, the conductive element is not present in every third slot in a respective sector of the stator.

4. The electric machine of claim 1 in which the conductive elements are spaced from at least a segment of the radial end portions of the posts to define axial flow paths adjacent to the radial end portions of the posts.

5. The electric machine of claim 1 in which at least some of the conductive elements are spaced circumferentially from at least some posts that define slots through which the at least some of the conductive elements extend.

6. The electric machine of claim 1 further comprising electrical connections between axially adjacent conductor elements to serially connect the electrical flow paths of the axially adjacent conductor elements.

7. The stator of claim 1 in which, at least for some conductive element, the conductive element has an end turn around a corresponding post and a portion within a slot and the conductive element at the end turn has a first width in a direction away from the corresponding post and the portion within the slot has a second width in a direction away from the corresponding post and the first width is greater than the second width.

8. The stator of claim 7 in which the first width is constant around the end turn.

9. The stator of claim 1 in which the conductive elements each form single layers around the posts, measured in a direction away from the posts.