Synchronous machine excited by permanent magnets

The invention relates to a permanently excited synchronous machine according the preamble of claim 1.

Such a machine is known from the DE-U-88 16 122nd In this machine, the permanent magnets on the periphery of the rotor core arranged. For secure mounting of the magnets, in particular at high speeds, a is of non-magnetic Material existing cylinder on the permanent magnets pushed. This requires a considerable manufacturing effort, since this cylinder rotatably connected to the rotor must become. The distributed uniformly over the circumference of the rotor Arrangement of the permanent magnets also does not lead to optimum electrical utilization of the machine.

The US Patent 4,939,398 describes a permanent magnet synchronous machine with a stator having a winding and a rotor which is equipped with permanent magnets. The Permanent magnets are inserted the receiving openings, said closed circumferential contour of the receiving opening. Each pole gap has a radially directed scattering slit on it. The permanent magnets are arranged in V-shaped and have their Middle and a maximum at its end a minimum distance the outer circumference of the rotor core.

The disadvantage here is that despite these structural features the magnetic field extends not sinusoidal and consequently the Polkräfte occur asymmetrically. Thus, electromagnetic Vibrations excited.

The invention is based on the object, a permanent-magnet Synchronous machine of the generic type such that those with despite the design for high speeds is considerably less production effort to produce and having improved electrical properties. It is, among other things a comparatively improved overload capacity and a extended speed range of the synchronous machine sought.

The object set is achieved by the plate the specified claim 1. By introducing of the permanent magnets in the receiving openings of the circumferentially closed rotor core, the permanent magnets against the centrifugal stress at high speeds protected. Through the appropriate spatial arrangement of Permanent magnets per pole of the machine is a Flußsperre for stator current excited armature transverse field and also from one pole the other pole on the pole gap across a bypass for a reach field weakening stator flux.

The fact that the outer contour of the rotor core designed is that between the rotor and the stator current Air gap in the pole center is the smallest and enlarged to the pole gaps out, is at least approximately achieved sinusoidal profile of the magnetic field. this leads to to uniform, symmetric Polkräften so that the electromagnetic minimizing power and vibrational excitations are. In order for the machine as a whole is very stable vibration. Another essential aspect of to the Pollükken towards increasing air gap is impeding the armature transverse field and the reduction of shunt inductance.

The appropriate design of the outer contour of the rotor core is easily flattened by a course achieved between the pole centers. The air gap between the rotor and the stator is thus in the pole center on smallest, so that here a high maximum air gap induction is given, which in turn, a high torque / power ratio results. Furthermore, can the outer contour the rotor core in conjunction with the stator bore as a flow channel for a possible natural ventilation use.

Especially on machines with a number of pole pairs equal to or greater 2 allows the described spatial arrangement of Permanent magnets in the rotor core, the formation of the wave of Runner as a hollow shaft. A version with hollow shaft is particularly for use of the machine in the field of machine tools low because through the hollow shaft through an access to the machine tool is.

Using an electric illustrated in the drawing in section Machine the invention is described in more detail below.

With 1 of the stator of an electric synchronous machine is called, in the stator slots 2 a in the drawing Stator winding not shown is introduced. In the Stator bore 3 is excited by permanent magnets 4 runners 5 disposed of, by means of a hollow shaft 6 in corresponding mounted attached to the stand bearing plates rotatably is. On the hollow shaft 6, the rotor core 7 of the rotor 5 applied.

In the rotor core 7 are each pole two slotted provided receiving openings 8, are used in the permanent magnets 4 are. The spatial profile of the two receiving openings 8 of one pole is designed so that the receiving openings 8 with its one end to the pole center 9 out as close as possible to come close to the outer circumference of the rotor core. 7 The others, to the pole gap 10 towards extending the end of the receiving openings 8, on the other hand with respect to the entire course the receiving openings 8 at the greatest distance to the outer periphery the rotor core 7. In the pole gaps 10 of Machine is provided in each case nor a scattering slit 11th also , the rotor core 7 on the outer periphery of a pole center 9 to the other pole center 9 a flattened History 12. This results in the pole center 9 the smallest air gap width. From the pole center 9 to the pole gaps 10 out increases the air gap and reached the pole gap 10 its greatest value.

The described course of receiving openings 8 in Area of ​​a pole results in the pole center 9 terms the magnetic cross-section of the rotor laminations a bottleneck. The constriction acts as Flußsperre for the stator current excited armature transverse field. Thus, the influence of the Armature transverse field weakened on the machine behavior. This leads to the well at a wide power control range Machine nor a largely linear relationship between Current and torque remains. For the between two Poland lying pole gap 10 towards increasing the magnetic cross-section the rotor laminations to. This is between two pole centers 9, a bypass for an induced by the stator ago field-weakening flow. This requires on the one hand a relatively low power requirement for a necessary speed control Field weakening, on the other hand, a further speed control range allows.

The different magnetic cross-sections in the pole centers 9 and the pole gaps 10 result in the reduction of Shunt inductance, resulting in a corresponding increase the tilting moment of the machine results. The machine has characterized a large overload capacity on.