Shark -new motor design concept for energy saving- applied to - VBN

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Chapter 2 Linear analysis of the Shark switched Reluctance Motor
If the length, l shk , of the Shark profile remains constant then the inductance and the energy gains
both increases with the increasing height, h shk , of the profiles.
energy gain
10
9
8
7
6
5
4
3
2
h shk /g=15 square profile
h shk /g=1
elliptic profile
trapezoid profile (k=0.3)
saw profile
square profile
elliptic profile
trapezoid profile (k=0.3)
saw profile
1
0 5 10 15 20
l /g
shk
25 30 35 40
Fig.2.22 Illustration of the energy gain variation as a function of the length and height of the Shark profile
According to this linearised analysis the square wave profile exhibits the best magnetic
performances compared to the other shapes of Shark teeth analysed. The best performances of the
square wave profile are obtained for large β , which is equivalent to a large ratio of the height to
the length of the profile. This may be seen in Fig.2.19, Fig.2.20, Fig.2.21 and Fig.2.22. This means
that the optimum Shark configuration comprises a square wave air gap whose teeth are as high and
narrow as possible. However, when selecting these dimensions there will be some limitations.
The height of the Shark teeth is limited as the presence of the Shark teeth reduces the available
winding area. In this project, the height h shk of the Shark profile was limited to about 20 [%] of the
height of the stator pole. For the SRM, with the dimensions given in Appendix B1, this limit is 4.5
[mm]. The length of the Shark tooth is limited by the lamination thickness. The shortest square
wave Shark tooth that could be built has the length lshk = 3 ⋅ llam
, where l lam is the thickness of the
lamination as shown in Fig.2.23.