Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1992-12-16
1994-05-24
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310156, 310184, 310254, 310261, H02K 2100
Patent
active
053151984
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a synchronous machine of the kind set forth below.
The large majority of such synchronous machines are rotary machines, the rotor of which is normally cylindrical. Accordingly, the invention will be described primarily with reference to such machines. It will be understood, however, that the invention can also be applied to rotary machines which are equipped with rotors of other configurations, for instance disc-like rotors or conical rotors, and also to linear machines.
According to conventional techniques, it is customary in a synchronous machine, the armature winding of which shall have a sinusoidal terminal or line voltage, or, in the case of a motor, is supplied with a sinusoidal terminal current, to design the armature winding, which is normally mounted on the stator of the machine, and the field magnet system, which is normally mounted on the rotor, such that the density of the flux which exists in the air gap between the stator and the rotor, and which is linked with the armature winding, is distributed sinusoidally as seen along the direction of movement of the two relatively movable parts of the machine, i.e. over the circumference in the case of a conventional rotary machine. This applies irrespective of whether the field system comprises salient field poles provided with permanent magnets or electromagnetic field coils, or comprises a distributed field winding mounted on a ferromagnetic iron core, for instance on a cylindrical rotor core. In the case of machines provided with salient field poles, it is sometimes possible to tolerate some deviation from the desired sinusoidal distribution of the air-gap flux-density, namely such deviations as those caused by deviations in the shape of the permanent magnets or the pole shoes from the theoretically ideal shape, which substantially simplify the manufacture of the permanent magnets or the pole shoes.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a synchronous machine of the kind described in the introduction which has a higher induced voltage, and consequently a higher rated output than earlier known synchronous machines of this kind that are constructed in a conventional manner.
This object is achieved in accordance with the invention, in a synchronous machine, by dispensing with the earlier desired sinusoidal distribution of air-gap flux-density and instead employing a flattened distribution function for air-gap flux-density.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail with reference to the accompanying drawings, in which
FIG. 1 is a diagram illustrating the inventive function used to vary the mean value of the air-gap flux along the direction of relative movement of the two relatively movable parts of the machine;
FIG. 2 is a diagram which illustrates the amplitude of the fundamental or dominant wave and certain of the harmonic or superimposed waves of the function according to FIG. 1;
FIG. 3 illustrates schematically one possible configuration of the permanent magnets of a machine provided with permanently-magnetic field poles in accordance with the invention;
FIGS. 4, 5, 6a-6d and 7a-7c illustrate schematically conceivable constructions of the field magnet system and the armature winding of an inventive machine, particularly a machine in which the field magnet system comprises permanently-magnetic field poles;
FIGS. 8a and 8b are diagrams which illustrates the measured induced phase voltage and the measured line voltage respectively of the armature winding in an inventive machine constructed as illustrated in FIG. 7;
FIG. 9 is a diagram which illustrates the path of the voltage vector for the same machine, as measured with the aid of a vector-visualizing instrument;
FIGS. 10a-10c illustrate schematically a further conceivable construction of the field magnet system in an inventive machine, particularly in a machine having salient field poles with electromagnetic field coils,
FIG. 11 shows a portion of a typic
REFERENCES:
patent: 5140210 (1992-08-01), Shirakawa
patent: 5162685 (1992-11-01), Yamaguchi et al.
patent: 5170085 (1992-12-01), Shinto
Electric Machinery, by Fitzgerald et al.; pp. 121-133; (no month) 1983; McGraw-Hill, New York, N.Y.
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