DE10121022A1 - Electrical machine - Google Patents

Abstract

The invention relates to a salient pole synchronous machine comprising a stator and a rotor, which form an air gap between them. The stator or the rotor have pole shoes that support field windings. The invention is characterized by the following feature: the pole shoes are, when viewed in an axially vertical section, structured so that the air gap enlarges in the rotational direction of the rotor.

Description

The invention relates to an electrical machine, in particular one Salient.

Such machines have a stator and a rotor. The rotor are assigned to pole pieces. The pole pieces wear a field winding Generation of a magnetic excitation field in the air gap. In the fixed Armature windings are provided for the stator.

The contour of the pole shoes is in a salient pole machine generally designed in such a way that an almost in the air gap at idle there is a sinusoidal induction curve.

It is known that the induction at nominal load (= active load) is greater than at idle. Under load, however, with tooth and rotor pole saturation in In the area of peripheral force formation. This leads to increased Losses in the stator winding as well as the so-called Lion heart loss with the tooth relief field as the cause. by virtue of saturation is also the calculation of the excitation current Uncertainties.

The invention has for its object a salient pole machine to be designed in such a way that the aforementioned lion heart losses are reduced or be avoided, and that the required excitation current is more accurate can be calculated.

This object is solved by the features of claim 1. Accordingly, the pole pieces - in an axially perpendicular cut seen - designed so that the air gap in the circumferential direction of the  Rotors enlarged. The maximum value is therefore on the Force defending.

The inventor recognized the following: when transitioning from idle to Nominal load occurs on one side of the pole piece - in the direction of rotation of the rotor seen - a sharp increase in induction on. It is about around that side of the pole piece on which the torque-generating force attacks. However, according to the invention, the pole piece becomes asymmetrical designed that the air gap - seen in the circumferential direction of the rotor - expanding on one side, so the induction over the salient pole shoe uniform. This makes the magnetic force - more accurate said of their tangential component - already about half of the Torque formed.

You could the measure according to the invention with the Compare blade adjustment of wind rotors. Analogously, this could be done the poles or their geometric are also thought Make configuration changeable and the respective load adapt. However, this is generally not necessary because many - electrical machines run at a constant nominal load, for Example generators of hydropower plants. Therefore, the Pole shape be designed from the outset in such a way that Nominal load gives the optimal induction.

The invention has another advantage. Because the amplitude of the Voltage lies approximately in the center of the pole, i.e. in the main magnetic axis, the stability improves. The excitation winding is no longer there exclusively in the magnetic longitudinal axis of the pole piece.

The invention can also be used in hydropower plants with pump turbines apply. The direction of rotation reverses when the engine is running  compared to generator operation. However, what is not reversed is the direction of the torque solely by the invention asymmetrical pole shoes is specified.

So far, the idea of asymmetrical pole pieces has not been possible arise because the specialist only had to see disadvantages. The The problem only appeared when the machines were used ever higher, that means with higher induction operation. In fact, the behavior is one Machine with asymmetrical pole pieces at idle is less favorable because the Voltage curve becomes less favorable due to the asymmetry and because in the Idle lion heart losses occur. It is crucial, however, that at Losses are minimized and thus the operation is optimal. One could thus use the asymmetrical according to the invention Pole shoe shape speak of a load case-optimized shape.

In summary, the invention provides the following advantages:

• 1. The lion heart losses (longitudinal field losses) in the Stand development is almost completely eliminated at nominal load.
• 2. The current-dependent losses in the pole shoe surface through finite number of uses also decrease significantly at nominal load.
• 3. The pole horns are relieved of extreme saturation at nominal load; this allows the excitation current to be calculated more precisely.
• 4. The static and dynamic stability are greater than at nominal load with conventional pole shoes, with the same excitation current.
• 5. The field curve at nominal load can be adapted to the ideal shape.  
• 6. Generators according to the invention can also be used Use pump turbines regardless of the change in Rotation.

The invention and the prior art are based on the drawing explained in more detail. The following is shown in detail:

Fig. 1 illustrates an asymmetrical pole piece with associated induction diagram.

Fig. 2 illustrates a conventional pole piece with associated induction diagram.

Fig. 3 illustrates the course of the losses in the stator winding through the tooth relief field over the load, namely for inventive and conventional pole pieces.

Fig. 4 is a performance diagram showing the static and dynamic stability in asymmetrical and conventional pole pieces.

Claims (1)

1. salient pole synchronous machine;

• 1. 1.1 with a stator and a rotor, which form an air gap between them;
• 2. 1.2 the stator or the rotor have pole shoes;
• 3. 1.3 the pole pieces wear field windings;
• 4. 1.4 the pole pieces are - seen in an axis-perpendicular section - designed such that the air gap increases in the direction of rotation of the rotor.