HRP990222A2 - Magnetic core of alternative part of rotary engines made of magnetic sheet metal - Google Patents

Description

The field to which the invention relates

This invention relates to the construction of the magnetic core of the alternating part of rotary electrical machines (generators and motors).

Technical problem

The magnetic core of the AC part of rotating electrical machines is exposed to a variable (most often sinusoidal) magnetic field. Due to the change in the direction of the field, energy losses occur, which cause heating of the magnetic core. In order to reduce losses and thereby increase the efficiency of the machine, it is necessary to use materials with the best possible magnetic characteristics. The material with the least energy losses is steel cold-rolled oriented sheet. This material is not used in rotary machines, because it shows its good characteristics only in one direction of the magnetic field, and in the magnetic core of the alternating part of rotary electric machines, the magnetic field deviates in various directions.

State of the art

In the existing constructions of the magnetic core of the alternating part of rotary electric machines, a steel cold-rolled non-oriented sheet is used, which has worse characteristics than the oriented one, but therefore has the same characteristics in all directions of the magnetic field. Steel cold-rolled oriented sheet is used only in transformers where the magnetic field in the entire core is in one direction, and the sheet is adapted to that direction.

Presentation of the essence of the invention

The aim of the invention is to enable the use of cold-rolled oriented sheets in the construction of the magnetic core of the alternating part of rotary electric machines, thereby reducing energy losses, i.e. increasing the usefulness of the machine. Secondary objectives are:

- simplification of the cooling device due to lower energy losses, i.e. less heat that needs to be removed from the machine

- better use of sheet metal when cutting

- lower magnetization current

The construction of the magnetic core of the alternating part of rotary electric machines with steel cold-rolled oriented sheet is performed so that the core is divided in the radial direction into two parts. The first part is represented by the teeth of the magnetic core where the magnetic field is directed radially, and the second is the yoke of the core where the magnetic field is directed approximately tangentially. Each of these parts of the core is made of special sheets and then put together into one unit that is clamped in the usual way

Brief description of the drawing

Figure 1 cross-section of a section of a common magnetic circuit of a synchronous machine with highlighted poles

Figure 2 is a common sheet segment of the alternating part of the magnetic core of a rotary machine

Figure 3 segment of the sheet of the magnetic core of the alternating part of rotary electric machines made of magnetically oriented sheet

Fig. 4 parts of the sheet segment of the magnetic core of the alternating part of the rotating electrical machines made of magnetically oriented sheet 4.

Figure 5 tooth overlap of two axially adjacent sheet metal layers

List of marks on the drawings:

1. alternating part of the magnetic core of a synchronous machine with salient poles

2. yoke

3. winding slots

4. the direction of the magnetic field

5. magnetic orientation of the sheet

6. yoke sheet segment

7th segment of the tooth plate

8. groove for wedging the tooth sheet segment into the yoke sheet segment

Description of the realization of the invention

One segment of the magnetic core is not cut so that the slots for the winding remain on it, but slots are cut for wedging the teeth of the magnetic core. The grooves for wedging the teeth into the yoke and the teeth of the magnetic core are not equal on each sheet layer (in the axial direction), but are made so that the joints of the teeth and the yoke of each subsequent sheet layer (in the axial direction) overlap with the previous one. This prevents the possibility of a conductive connection at the edges of the sheets and thus eddy currents that cause losses. Likewise, the edges of the core yoke segments overlap from layer to layer. In the event that the magnetic core must be delivered in several pieces (e.g. for assembly on machines with a horizontal axis, maintenance, etc.), then the sheet segments at the end of the piece being performed must be edge-aligned in order for the second piece to fit properly and at the cost of possible galvanic junctions of edges and eddy currents (which should be prevented by other measures, such as additional insulation). Therefore, the magnetic core should be made from as few pieces as possible, preferably in one piece.

Method of application of the invention

The magnetic core of the alternating part of rotary electric machines made of magnetically oriented sheet metal in all its characteristics, except for losses, is equal to the standard magnetic core of the alternating part of rotary electric machines and is therefore used for installing windings in the classic way.

Claims (4)

1. Laminated magnetic core of the alternating part of rotary electric machines, characterized by the fact that it is made of magnetically oriented sheet metal, and this is done so that the core and tooth yoke segments are cut separately, and when assembled, they are joined by a tight fit of the tooth sheet segment to the yoke sheet segment. 2. Laminated magnetic core according to claim 1 characterized by the fact that the sheets of the yoke are cut so that the magnetic orientation of the sheet in these segments is approximately tangential 3. Laminated magnetic core according to claims 1 and 2, indicated by the fact that the tooth sheets are cut so that the magnetic orientation of the sheet in these segments is longitudinally along the tooth 4. Laminated magnetic core according to claims 1 to 3, characterized by the fact that the joints of the teeth and the yoke are cut so that these joints on two adjacent layers of sheet metal are radially displaced so that a overlap is realized.