DE102015118576A1 - STATOR FOR AN ELECTRIC MOTOR - Google Patents

Abstract

The stator (11) according to the invention has three substantially T-shaped stator poles (7), which are each arranged at 120 ° to each other, and six substantially L-shaped stator poles (12), which are regularly spaced, in pairs between the T. -shaped stator poles (7) are arranged. The pole shoes (9) of the L-shaped stator poles (12) are each facing away from the directly adjacent T-shaped stator poles (7). Furthermore, the stator (11) has in each case one phase winding (A, B, C) for each of the three phases, wherein each of the three phase windings (A, B, C) has in each case an inner winding (14) and an outer winding (15). wherein the outer and inner coils (14, 15) are electrically connected together. The inner winding (14) is in each case wound around a T-shaped stator pole (7) and the outer winding (15) is wound in each case around the two L-shaped stator poles (15) which are directly adjacent to this T-shaped stator pole (7) in that the inner winding (14) is disposed substantially coaxially within the outer winding (15) and forms a common electrical pole with the outer winding (15).

Description

The invention describes a stator for a two-pole, three-phase electric motor, in particular for high rotational speeds.

High-speed electric motors are needed for various applications, such as vacuum cleaners.

Compared to servo motors, it is not important in such simple applications how exactly the motor is controllable. Here it is only important that the engine reaches a high speed and is as simple and inexpensive to produce.

Therefore, motors with only two magnetic poles and three phases are often used for such applications. This makes the commutation very easy to implement. The rotor requires only a two-pole magnet, which is why such a motor is inexpensive overall.

In the prior art, many designs for bipolar, three-phase electric motors are known, of which three stators in the example 1 to 3 are shown.

The 1 shows a first known embodiment in which the stator has three stator poles, around each of which a phase winding of an electrical phase is wound. However, this embodiment has the disadvantage that due to the geometry of the stator poles and the pole pieces, an automatic complete winding of the stator poles is not or only with difficulty possible. This design has a low degree of filling and therefore only a small achievable magnetic field strength. Since the entire flux has to be generated by a winding and the pile shoes have to be relatively narrow in favor of the windability, the pole shoes quickly saturate, which reduces the efficiency. To prevent saturation, the pole pieces must be made thicker, which increases the mass and cost of the stator.

To circumvent the problems of saturation and winding, stators with six stator poles are also used, as exemplified in US Pat 2 shown. In this embodiment, the windings can be distributed or concentrated. In a concentrated winding arrangement as in 3 (a) Each phase has two windings, each offset by 180 ° on a stator pole. The distributed arrangement of the phase windings, however, complicates the winding and the problems with the degree of filling remain essentially the same. Furthermore, the torque factor is lower in this arrangement. In addition, the current at the same load is greater whereby the efficiency is reduced.

In a distributed winding arrangement as in 3 (b) Each winding is wound over two stator poles offset by 180 °. This means that the winding wires of the individual phases intersect several times. As a result, the winding is very difficult, making this arrangement is difficult to use for small engines and in particular makes the series production for small engines almost impossible.

The object of the invention is therefore to provide a stator for an electric motor can be wound easily and with a high degree of filling, which is inexpensive to produce and has a high efficiency.

This object is achieved by a stator having the characterizing features of the main claim. Further advantageous embodiments are shown in the subclaims and in the drawings.

The stator according to the invention has n> = 2 stator poles, which are T-shaped and each arranged at an angular distance of 360 ° / n to each other, and 2n stator poles, which are L-shaped, regularly spaced and in pairs between the T shaped stator poles are arranged. The pole shoes of the L-shaped stator poles are each facing away from the directly adjacent T-shaped stator poles.

Preferably, the stator according to the invention is used in a three-phase, two-pole electric motor.

A T-shaped stator pole has two pole pieces, which are arranged in a known manner in the circumferential direction on both sides of the pole core. An L-shaped stator pole has only one side such a pole piece.

Furthermore, the stator has a respective phase winding for each of the three phases, each of the three phase windings each having an inner winding and an outer winding, and the inner and outer windings being electrically connected to one another. The inner winding is wound around a T-shaped stator pole, respectively, and the outer winding is wound around the two L-shaped stator poles directly adjacent to this T-shaped stator pole, so that the inner winding is disposed substantially coaxially within the outer winding and forms a common electrical pole with the outer winding.

The stator according to the invention therefore has a total of nine stator poles, but on which only six windings are arranged in the arrangement according to the invention.

The inner winding and the outer winding electrically form a phase winding. This means that the magnetic field strength of the two windings adds and these form a magnetic pole. Each of the two individual windings can therefore have correspondingly fewer turns and / or consist of thinner wire. The achievable field strength is much higher than would be achieved if the stator poles would be wound conventionally.

In addition, the arrangement of the pole pieces of the L-shaped stator poles facilitates the winding of the stator poles.

The stator poles can therefore be wound much easier overall and it can be a higher degree of filling can be achieved. As a result, a higher efficiency and a greater field strength is achieved in addition.

Overall, a cost-effective stator is created by the arrangement according to the invention, which solves all the above problems.

The three phase windings can be controlled in a star connection or delta connection.

The inner winding and the outer winding can be connected in series in a preferred embodiment of the invention.

If it is ensured that the electromagnetic force (EMF) of the two windings is equal, the inner winding and the outer winding can preferably also be connected in parallel. This has the advantage that the windings can have different wire diameters to match the EMF. The outer winding then has fewer turns and can thus be wound with thicker wire. As a result, the winding resistance decreases whereby the efficiency is additionally increased.

In an advantageous embodiment of the invention, the stator at the axial ends in each case a winding support, which serves as a guide and insulation for the phase windings.

The winding carriers may for example consist of plastic.

Preferably, all stator poles, regardless of whether T- or L-shaped in the radial direction. In another preferred embodiment of the invention, the T-shaped Statorpol extends radially, while belonging to the same electrical pole adjacent L-shaped stator poles parallel to the T-shaped stator pole.

The invention is explained in more detail by means of embodiments with reference to the drawings. In the figures show:

1 FIG. 4 shows a cross-section through a stator according to the prior art with three stator poles and three windings, FIG.

2 FIG. 2 shows a cross-section through a stator according to the prior art with six stator poles and six windings, FIG.

3 (a) FIG. 1 shows a winding scheme for a stator with six windings with a concentrated winding arrangement, FIG.

3 (b) FIG. 1 shows a winding diagram for a stator with six windings with distributed winding arrangement, FIG.

4 FIG. 2 shows a cross section through a stator according to the invention with nine stator poles according to a first embodiment, FIG.

5 : a winding scheme for the stator of 4 in which the inner windings and outer windings are each connected in series in a star connection,

6 : a winding scheme for the stator of 4 in which the inner windings and outer windings are each connected in parallel in a star connection,

7 : a winding scheme for the stator of 4 in which the inner windings and the outer windings are each connected in parallel in a triangular circuit,

8th : a winding scheme for the stator of 4 wherein the inner windings and outer windings are each connected in series in a triangular circuit,

9 FIG. 2 shows a cross section through a stator according to the invention with nine stator poles according to a second embodiment, FIG.

10 : an oblique view of the stator of the 4 .

11 : An oblique view of the windings of the stator 9 .

12 FIG. 2: an oblique view of a two-part winding carrier with stator windings, FIG.

13 : An oblique view of a winding carrier and

14 : a detailed view of the windings in the area of the winding carrier.

The 1 shows a cross section through a two-pole, three-phase motor 1 according to the prior art. The motor 1 has a rotor 2 with a wave 3 and a rotor magnet 4 , The rotor magnet 4 has two magnetic poles 5 on. The motor 1 still has a stator 6 with three T-shaped stator poles 7 , Each stator pole 7 has a pole core 8th and two pole shoes 9 , the two sides of the pole core 8th protrude from this in the circumferential direction. The three-phase engine 1 has three phase windings A, B, C each around a pole core 8th are wound.

The 2 shows a cross section through another two-pole, three-phase motor 1 according to the prior art, which is essentially the 1 equivalent. The stator 10 however, has six T-shaped stator poles 7 , Each phase winding A, B, C is divided into two individual windings.

The phase windings A, B, C can in this arrangement according to the 3 (a) be concentrated, with each single winding 23 each around a stator pole 7 is wound.

In a distributed arrangement according to the 3 (b) Each individual winding is two stator poles offset by 120 ° 7 wound. However, there is the difficulty in winding that the phase windings A, B, C cross several times, whereby the winding is additionally difficult.

In 4 is a cross section through a stator 11 shown according to a first embodiment of the invention. In contrast to the prior art, this stator has nine stator poles according to the invention. Three substantially T-shaped stator poles 7 are each arranged in the circumferential direction at an angle of 120 ° to each other. Six substantially L-shaped stator poles 12 are evenly spaced in pairs between the T-shaped stator poles 7 arranged. In this embodiment, all the stator poles are formed substantially radially. The L-shaped stator poles 12 each have only one pole piece arranged on one side 9 , The pole shoes 9 the L-shaped stator poles 12 are each the directly adjacent T-shaped stator poles 7 arranged away. This results on both sides of a T-shaped stator pole 7 a larger opening for winding the stator gap 13 , It can thereby be achieved a higher degree of filling, at the same time easier windability.

The three phase windings A, B, C are each formed in two parts, but each have an inner winding 14 and an outer winding 15 on, which are electrically connected to each other. The inner winding 14 is in each case about a T-shaped stator pole 7 wound, as in the winding scheme of 5 clarified. The associated outer winding 15 is each about the two directly adjacent L-shaped stator poles 12 wound. The inner winding 14 and the outer winding 15 can each be either electrically connected in parallel or in series. A mixed configuration, ie one phase winding in parallel and another in series, would be technically feasible but has no apparent advantage.

The inventive arrangement is the inner winding 14 essentially coaxially within the outer winding 15 , It must be ensured that the current flows through the two windings in the same direction. Magnetic fields then form in both windings pointing in the same direction, adding up the magnetic field strength of the two magnetic fields. The inner winding 14 and the outer winding 15 form a common electrical pole.

The absolute size of the magnetic fields and therefore also the number of turns of the inner winding 14 and the outer winding 15 can vary, with the exact number of turns depending on many conditions, such as rated speed, dimensions of the motor and many others.

Due to the different spatial conditions in practice, the number of turns of the inner winding 14 and the outer winding 15 never differentiate. In the example shown the 4 each has the inner winding 14 much more turns than the outer winding 15 ,

The advantage consists in the fact that a large magnetic field strength can be achieved by adding the two magnetic fields even with relatively small windings. Thus, the efficiency of the engine increases. This allows the stator 11 and thus an engine at the same power be designed to be much smaller overall.

Furthermore, the field strength per electric pole on four pole pieces 9 distributed, which also reduces the risk of saturation. The stator 11 , in particular the pole shoes 9 and the polkerne 8th can be made smaller thereby. All these advantages cause the stator 11 Total cost can be produced.

Nevertheless, the control of the stator according to the invention remains 11 simply because it is electrically seen a three-pole stator 6 according to the 1 equivalent.

As already explained, the invention is equally suitable for a star or delta connection of the motor phases. Likewise, in both circuit arrangements, the inner windings and the outer windings may each be connected either in parallel or in series.

The winding scheme of 5 shows a star connection of the three motor phases A, B, C in which the inner windings and the outer windings are each connected in series.

The 6 shows a winding diagram of a star connection of the three motor phases A, B, C in which the inner windings and the outer windings are connected in parallel.

In 7 3, a winding diagram for a delta connection of the three motor phases A, B, C is shown, in which the inner windings and the outer windings are respectively connected in parallel.

In 8th 3, a winding diagram for a delta connection of the three motor phases A, B, C is shown, in which the inner windings and the outer windings are each connected in series.

In 9 a cross-section through an alternative embodiment of a stator according to the invention is shown. Unlike the execution of the 4 Here are the L-shaped stator poles 12 not radially formed, but to a T-shaped stator pole 7 both directly adjacent L-shaped stator poles 12 are formed substantially parallel to this. This means that all the stator poles of a common electrical pole are formed parallel to one another.

Through this geometric arrangement is the outer windings 15 more winding space 13 to disposal. As in 8th can be seen, in this embodiment, the outer winding 15 much more turns than the inner winding 14 ,

In addition to these two shown geometrical arrangements of the stator poles, there are countless other possible equivalent arrangements, which is why the invention is in no way limited to the arrangements shown.

The 10 shows an oblique view of the stator 11 according to the execution of 4 in which all stator poles run radially inwards. The stator consists for example of individual stator laminations 16 which are stacked in the axial direction.

The 11 equals to 10 wherein here only the phase windings A, B, C are shown schematically to illustrate the winding arrangement. In this illustration, the substantially coaxial arrangement of the inner windings is particularly clear 14 to the respective outer windings 15 to see.

The 12 shows an oblique view of the windings according to the 11 on a winding carrier 17 are arranged. This winding carrier 17 is made of plastic, preferably injection molded, and serves to accommodate and guide the windings on the stator 11 , The winding carrier 17 is in the embodiment shown here in two parts in the axial direction, but may also be formed in several parts (not shown in the drawing).

The 13 shows such an item 20 , The two items 20 Both sides are axially in the stator 11 inserted and then wound.

To guide the windings has the winding support 17 at the axial ends on the inner circumference in each case in the axial direction extending projections 21 and on the outer circumference a circumferential edge 22 , so that the windings in the axial direction completely within the winding support 17 lie. So that the inner windings 14 not the outer windings 15 Touch points the winding support 17 higher webs at the outer windings 19 on. As a result, the winding process can be improved because the inner windings 14 no obstacle to the outer windings 15 represent.

In 14 is a detailed view of a stator 11 with a winding carrier 17 shown. The winding carrier 17 encloses all stator sheet metal parts and thus serves as slot insulation between the individual windings.

LIST OF REFERENCE NUMBERS

1

engine

2

rotor

3

wave

4

rotor magnet

5

magnetic pole

6

Stator 3 pol

7

Stator pole T-shaped

8th

pole core

9

pole

10

Stator 6 pol

11

Stator 9 pol

12

Stator pole L-shaped

13

Statorzwischenraum

14

inner winding

15

outer winding

16

stator lamination

17

winding support

18

web

19

Winding carrier item

20

projections

21

edge

22

winding

A, B, C

phase windings

0

star point

Claims (9)

Stator for a brushless electric motor ( 1 ) with stator poles ( 7 ) and phase windings (A, B, C) around the stator poles ( 7 ) are arranged, characterized in that the stator ( 11 ) a number of n> = 2 stator poles ( 7 ), which are T-shaped and each arranged at an angular distance of 360 ° / n to each other, that the stator ( 11 ) a number of 2n stator poles ( 12 ), which are L-shaped, are regularly spaced and in pairs between the T-shaped stator poles ( 7 ), the pole shoes ( 9 ) of the L-shaped stator poles ( 12 ) each directly adjacent T-shaped stator poles ( 7 ) are turned away, that the stator ( 11 ) has a respective phase winding for each of the n phases (A, B, C), each of the n phase windings (A, B, C) each having an inner winding ( 14 ) and an outer winding ( 15 ), which are each electrically connected to each other, wherein the inner winding ( 14 ) each about a T-shaped stator pole ( 7 ) and the outer winding ( 15 ) in each case around the two sides of this T-shaped stator pole ( 7 ) directly adjacent L-shaped stator poles ( 12 ), so that the inner phase winding ( 14 ) substantially coaxially within the outer phase winding ( 15 ) is arranged and a common electrical pole with the outer phase winding ( 15 ). Stator according to claim 1, characterized in that the inner windings ( 14 ) and the outer windings ( 15 ) are each connected in parallel. Stator according to claim 1, characterized in that the inner windings ( 14 ) and the outer windings ( 15 ) are each connected in series. Stator according to one of claims 1 to 3, characterized in that the stator ( 11 ) at the axial ends in each case one winding carrier ( 17 ), which serves as a guide and insulation for the phase windings (A, B, C). Stator according to claim 4, characterized in that the winding support ( 17 ) extending on its inner circumference in the axial direction projections 21 has and on its outer periphery a peripheral edge 22 having. Stator according to one of claims 4 or 5, characterized in that the phase windings (A, B, C) on webs ( 19 ) of the winding carrier ( 17 ) are arranged, wherein the webs ( 19 ) between the projections ( 21 ) and the peripheral edge ( 22 ) are arranged running in the radial direction and wherein the webs ( 19 ), on which the outer phase windings ( 15 ) are arranged to protrude further in the axial direction than the webs ( 19 ), on which the inner phase windings ( 14 ) are arranged. Stator according to one of claims 1 to 6, characterized in that the T-shaped stator pole extends radially, while belonging to the same electrical pole adjacent L-shaped stator poles parallel to the T-shaped stator pole. Three-phase motor ( 1 ) with a stator ( 11 ) according to one of claims 1 to 7. Two-pole motor ( 1 ) with a stator ( 11 ) according to one of claims 1 to 8.

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