It was found out manually that for the magnetic flux density in the air-gap B=1,0T, the magneto-motive force required is F
w=968mA.
For the same mmf F
w, the result obtained by FEMM, using magnetic material with the same quality as in Table 1, is B=0,942T.
This is an average value. Actually the distribution of the flux density B along the pole face is not uniform, due to the fringing effect.
In the central part of the pole B is less than at the pole edges. However the error of the manual calculations does not exceed 6%.
In Fig. 2 based on the data taken from the FEMM solution, the picture of the fringing is depicted.
The actual distribution of the flux density along the pole face (line C; A; Al; Cl) is presented in Fig. 3.
It is worth mentioning that the distance between the corresponding points C; A and Al; Cl is 10 mm.
Table 1
| B[T] |
0 |
0,025 |
0,25 |
0,5 |
1,0 |
1,5 |
1,6 |
1,7 |
1,8 |
1,9 |
| H[A/m] |
0 |
10 |
100 |
200 |
400 |
600 |
700 |
800 |
1200 |
2000 |
When the driving mmf is doubled F
w=1936 mA, the result obtained by FEMM is B=1,453T.
. . .
