Abstract
Rotating fields are the basis for most electric drives (induction and synchronous machines). First, the generation of a rotating field is discussed. As in the previous chapters, we start again from the basic electromagnetic laws. Both using a graphical depiction and a more mathematical method the rotating field generation is explained. Next, the emf is discussed. Finally, the torque on a (rotating) current layer in a (rotating) field is discussed.
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- 1.
Remark that the sign of \(j\gamma \) in Eq. 3.8 is opposite to that used in time phasors; more on that convention later on.
- 2.
One revolution of the rotor corresponds to \(2\pi \) mechanical radians and to \(2\pi .N_{p}\) electrical radians where \(N_{p}\) is the number of pole pairs; otherwise said the circumference of the rotor corresponds to \(2N_{p}\) pole pitches, i.e. \(2\pi r=2N_{p}\tau _{p}\) while each pole pitch corresponds to \(\pi \)electrical radians.
- 3.
Slots protect the windings but they also result in a useful spread of the forces on the iron.
- 4.
Actually, the notion mmf is, strictly spoken, always related to a closed field line but in machine theory it is also used in lieu of magnetic potential difference.
- 5.
In a diameter winding the coil width, i.e. the distance between entrance and exit conductors of a turn, is exactly one pole pitch.
- 6.
As mentioned above, in a diameter winding the coil diameter is equal to a pole pitch.
- 7.
In some winding arrangements m.
- 8.
- 9.
Give an interpretation of the last term?
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© 2018 Springer International Publishing AG
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Melkebeek, J.A. (2018). Rotating Field Machines: mmf, emf and Torque. In: Electrical Machines and Drives. Power Systems. Springer, Cham. https://doi.org/10.1007/978-3-319-72730-1_3
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DOI: https://doi.org/10.1007/978-3-319-72730-1_3
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Publisher Name: Springer, Cham
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Online ISBN: 978-3-319-72730-1
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