Flux-switching machine

Abstract

The present invention relates to a flux-switching machine, including a stator having phase windings and field coils, wherein, in the machine, at least one field coil is arranged in a pair of notches separated by at least three teeth.

Claims

1. A flux-switching machine comprising a stator bearing phase windings and excitation windings, wherein: each excitation winding comprises a first conductor and a second conductor, the first conductor of at least one excitation winding is arranged in a first groove, the second conductor of the at least one excitation winding is arranged in a second groove, and the first groove and the second groove are separated by at least three teeth.

2. The machine as claimed in claim 1, the grooves of the pair of grooves being separated by three teeth.

3. The machine as claimed in claim 1, said machine being a single excitation machine.

4. The machine as claimed in claim 1, comprising a single phase winding per groove.

5. The machine as claimed in claim 1, the teeth on the rotor and/or on the stator not being skewed longitudinally.

6. The machine as claimed claim 1, the number of teeth on the rotor n.sub.dr being equal to k11 or k13 and the number of teeth on the stator n.sub.ds being equal to k18, where k is an integer, not equal to zero.

7. The machine as claimed in claim 6, where k=1, 2 or 3.

8. The machine as claimed in claim 1, the teeth being regularly spaced circumferentially on the stator.

9. The machine as claim 1, said machine being three-phase.

10. The machine as claimed in claim 1, each phase winding encompassing two consecutive teeth.

11. The machine as claimed in claim 1, said machine constituting an alternator.

12. The machine as claimed in claim 1, wherein: the first conductor has a positive current, and the second conductor has a negative current.

Description

(1) The invention will be better understood upon reading the detailed description hereinafter of non-limiting embodiments of the invention and upon examining the accompanying drawing, in which:

(2) FIG. 1 schematically illustrates a known winding arrangement for a flux-switching machine,

(3) FIG. 2 shows an example of a machine according to the invention,

(4) FIG. 3 is a simulation result for a specific configuration of the rotor and of the stator, and

(5) FIG. 4 shows the waveform of flux as a function of the angular position for the configuration illustrated in FIG. 3.

(6) FIG. 1 shows a structure of a single flux-switching machine. The stator is shown linearly for reasons of simplification.

(7) The machine comprises a sequence of basic cells each formed by a groove containing the conductors E+ or E of an excitation winding and by two adjacent grooves receiving the conductors of the phase coils A+, A, B+, B, C+ or C, the machine being multi-phased, in particular three-phased, A, B and C denoting the phases.

(8) The excitation windings are connected conventionally to a source of direct current.

(9) By convention, the signs + and are attributed to the conductors depending on whether they have one direction or another within the groove. The same excitation coil thus comprises conductors E+ and E.

(10) The axis of each coil is oriented radially.

(11) The tooth pitch of the excitation coils is two, the grooves receiving the conductors of the excitation coils being separated by two teeth.

(12) FIG. 2 shows an example of a machine according to the invention, in which two grooves 3 and 4 receiving the conductors + and of the same excitation coil E are separated by three teeth 5, 6 and 7, and by two grooves 9 and 10 respectively receiving the windings of two different phases, for example A and B+ as illustrated.

(13) The grooves receiving the conductors + and of the same coil of a phase are separated by two teeth and by a groove receiving the conductors + or of an excitation winding.

(14) For example, as illustrated, the conductors A+ and A of the phase A are therefore received in grooves 9 and 11 separated by the teeth 5 and 12 and by the groove 3.

(15) The tooth 6 arranged between the grooves 9 and 10 is involved in the feedback of the flux, as can be seen in FIG. 3, which shows the flux lines for a machine having a specific configuration, that is to say a number of teeth on the stator n.sub.ds- equal to 18 and a number of teeth on the rotor n.sub.dr equal to 11. Further configurations are possible, in particular with n.sub.dr=k11 or k13 and n.sub.ds=k18.

(16) It can be seen in FIG. 3 that the rotor can be formed with protruding teeth 40, without pole shoes, distributed at uniform angles around the axis of rotation. The teeth 40 are each connected to an annular body 41, which is mounted on a shaft (not illustrated). The width of a rotor tooth is preferably, as illustrated, substantially equal to that of a stator tooth.

(17) The rotor and the stator are preferably formed by stacking electrical sheets.

(18) FIG. 4 shows the flux waveform for each of the phases as a function of the angular position of the rotor, for the configuration illustrated in FIG. 3.

(19) A machine according to the invention can be used in any application in which the voltage can be controlled by action on the excitation current, such as applications with variable load and/or speed.

(20) The machine according to the invention can function at constant voltage over a relatively substantial speed range.

(21) The invention is not limited to the illustrated example.

(22) For example, the grooves receiving the excitation windings and those receiving the phase windings may have different shapes and may be offset radially so as to facilitate the mounting of the coils and so as to reduce the axial bulk of the machine.

(23) Permanent magnets can be used on the stator, but the machine preferably is not excited using permanent magnets.