WO2008104156A2

WO2008104156A2 - Electronically commutated electric motor

Info

Publication number: WO2008104156A2
Application number: PCT/DE2008/000320
Authority: WO
Inventors: Hans Hermann Rottmerhusen
Original assignee: Metabowerke Gmbh
Priority date: 2007-02-28
Filing date: 2008-02-23
Publication date: 2008-09-04
Also published as: WO2008104156A3; EP2135343A2; DE102008007335A1

Abstract

The invention relates to an electronically commutated electric motor, which comprises a stator and a special rotor having rotor teeth and permanent magnets in a collector arrangement, said rotor being formed by a laminated core with grooves, wherein the ratio of the rotor teeth to the stator teeth is 1 to 0.75, and the orientation of the rotor poles relative to the stator field during operation of the motor is aligned such that even torque is achieved for each position of the rotor.

Description

Electronically co-grooved electric motor

The invention relates to an electronically commutated electric motor, according to claim 1.

Electronically commutated electric motors usually have a permanent magnet excited rotor, wherein the rotor is either equipped with individual permanent magnets, or on the rotor a multi-pole ring magnet is arranged, and in a rotor with a small diameter, the rotor is often itself from a multi-pole magnetized permanent magnet. The magnetization direction of the magnets or the magnet of such rotor is predominantly perpendicular to the air gap of the motor. The magnetization direction of the magnets can also be aligned transversely to the air gap by the permanent magnets on the rotor constitute a collector assembly.

DE 197 23 302 A1 describes such a solution. The rotor is formed with a reluctance-supported permanent magnet system, wherein the arrangement of the permanent magnets in the rotor is a collector arrangement. The rotor consists of a laminated core having rotor teeth and grooves therebetween, and in the grooves permanent magnets are arranged which are magnetized tangentially so that always two poles of the same polarity act on a rotor tooth, wherein the magnetization direction of the permanent magnets parallel to Air gap of the engine is aligned.

US 2006/0061228 A1 describes an electric motor in which the ratio of the rotor teeth to the stator teeth is 1: 0.75, and around each stator tooth is wound a coil which can be connected to a power source via an electronic control and between the rotor teeth in one ner collector assembly arranged permanent magnets, wherein the

Runner is designed such that the magnetic flux is predominantly via the permanent magnets and the stator, and does not escape to the center of the rotor.

For the arrangement of an electronically commutated electric motor often only a limited space is available. If such a motor now has a high power consumption, the motor is loaded with a high energy density. However, a high energy density also causes high heating and thus overheating of the engine.

The invention is therefore based on the object to provide an electronically commutated electric motor, which achieved at a small size high torques at each rotor position and has a high efficiency, and has a low heating in relation to the energy density.

This object is solved by the features of the independent patent claim 1. Advantageous design features of the invention are apparent from the remaining claims and the description.

Due to the special structure of the stator and rotor of the electric motor, the advantages are that with a small size high torques and high efficiency is achieved, and thus a low heating in relation to the energy density is achieved, the electric motor is highly resilient and overloadable, and by the dimensioning of the stator teeth and the special design of the rotor teeth, the electric motor is advantageously designed for a good draft ventilation. The invention is explained below with reference to the drawing.

Showing:

Fig. 1 u. 2 in an axial plan view of a representation of the stator and rotor of the electric motor,

Fig. 3 u. 4 in an axial plan view an alternative representation of the stator and rotor of the electric motor,

Fig. 5 in axial plan view another alternative representation of the stator and rotor of the electric motor, Fig. 6 shows a circuit arrangement of the electronic control device for commutation of the winding strands of the electric motor.

1 shows in axial plan view a view of the electric motor as an internal rotor with winding strands on the stator 1 and a permanent magnetically excited rotor 2. The stator has in a two-pole design of the winding strands six directed to the rotor stator teeth 3, wherein the winding strands each include two coils and the coils 4 of the winding strands each surround a stator tooth 3. The winding strands are placed during operation of the motor to a power source that stand on the stator opposite stator teeth each poles, and two adjacent stator teeth each unequal poles to each other. This Polbildung is marked on the stand with N, S. The stator teeth 3 are formed such that the width of the stator teeth to the air gap is at least about the width of the slot opening 5 from the one stator tooth to the adjacent stator tooth, and at most two thirds of the width, the width of a stator tooth plus the width of a slot opening of the stator equivalent. The six standing on the stator 1 stator teeth 3 are at the air gap 6 eight permanent magnetically excited Lauferzahne 7 opposite. Thus, the ratio of the rotor teeth to the stator teeth is 1 to 0.75.

The rotor 2 is designed as a permanent-magnet-excited reluctance rotor. The rotor teeth 7 of the rotor 2 form the stator pole faces of the PM excited rotor, the permanent magnets 8 are arranged in a collector assembly along the shaft of the rotor in a respective groove 9 extending perpendicular to the shaft, and each have the rotor tooth 7 facing pole face of the permanent magnets an eponymous polar formation to each other, which form the polar fields to the stator at the air gap. The width of the grooves 9 of the rotor 2 corresponds to the height of the permanent magnets 8, wherein the groove opening 10 of the grooves 9 is kept smaller in the region of the permanent magnets as the height of the Permanentmagne- te by the rotor teeth 7 have lugs 11 to the slot opening to a spin out to prevent the permanent magnets from the grooves.

To achieve a high efficiency of the motor, the width of the slot opening 10 of the grooves 9 of the rotor at the air gap in the region of the stator teeth is preferably about half the width of a stator tooth. 3

The permanent magnet width in the direction of the shaft is determined by the desired field strength directed towards the air gap, the wider the permanent magnets are designed, and the smaller the spacing of the permanent magnets relative to one another in the region of the shaft, the higher the field strength directed to the air gap on the rotor teeth , The rotor teeth 7 are arranged integrally on the shaft of the rotor 2, and are preferably formed from stacked sheets, thus the rotor body consists of a laminated disk set.

To achieve a high speed and a low detent torque, the volume of the permanent magnets is reduced accordingly. So that the slot openings directed to the air gap 10 of the rotor 2 of the one pole face to the adjacent pole face, which has the air gap directed pole face of the rotor teeth 7, at least about half the width of a stator tooth 3, the distance of the permanent magnets 8 to the stator teeth 3 is increased accordingly, and the rotor teeth 7 are each chamfered with a corresponding to the permanent magnet 8 nose 11, whereby the width of the slot openings 10 of the rotor at the air gap at least about half the width of a stator tooth is enlarged, and hereby a reduction in the efficiency of the electric motor, by the arrangement of permanent magnets with a low height, is prevented. The chamfer 12 of the rotor teeth 7, which forms a nose to the permanent magnets, is designed in a straight line.

For a design of the electric motor with a higher number of poles, the number of rotor teeth on the rotor in each case by four, and on the stator to increase the number of stator teeth by three. Thus, for example, the stator may have 6, 9, 12, 15 stator teeth, with the rotor then having 8, 12, 16, 20 rotor teeth, and the phase windings each include two, three, four and five coils, and then the rotor steps will increase accordingly a rotor revolution by the factor of the stator teeth of the electric motor.

Fig. 1 shows the rotor position, in which a runner step is preferably completed, in each case the trailing edge 13 and the leading edge 14 of each juxtaposed unlike pole field of the rotor, with respect to the direction of rotation of the rotor, approximately centrally to the front stator tooth each adjacent unlike excited stator teeth. Fig. 2 shows the completed runner step by reversing the

Winding strands, wherein at the same time the next runner step is initiated, and now is the respective running edge 13 and the leading edge 14 of each adjacent unlike pole field of the rotor, with respect to the direction of rotation of the rotor, approximately centered to the rear stator tooth of each adjacent unequal names excited stator teeth.

By arranging the number of rotor teeth on the rotor to the corresponding number of stator teeth on the stator, a rotor revolution consists of four times the number of rotor steps as the number of stator teeth, and thus, with an array of six stator teeth on the stator, one rotor revolution 24 runner steps.

Due to the arrangement of a higher number of rotor teeth on the rotor as the number of stator teeth, and a corresponding dimensioning of the stator tooth width and the groove width at the air gap of the electric motor, each field-leading a rotor step each field-excited stator tooth two adjacent unlike pole fields of the rotor are assigned , whereby an ideal flux of the magnetic fields is achieved, and thereby a maximum torque, and a very high efficiency is achieved, whereby a low heating of the electric motor is justified.

It may be advantageous if the electric motor has a rotor which has a relatively large diameter with respect to the outer diameter of the electric motor in order to achieve an even higher torque.

In Fig. 3 and 4, such an electric motor is shown. The laminated core 15 of the stator 1 is held so that the Runner 2 has a relatively large diameter, for this purpose, the stator teeth 3 are provided with narrow pole horns 16, and the inference 17 on the laminated core of the stator is also designed to be very narrow, so that in each case for accommodating the coil on the stator tooth a space required for this is available. The slot openings 18 of the stator to the air gap 6 from the one stator tooth to the adjacent stator tooth are variably interpretable in this design of the stator, they can be designed as a small slot opening up to a very large slot opening.

The distance of the permanent magnets 8 of the rotor to the stator teeth 3 is also dependent on the width of the slot openings 18 on the stator and the slope of the chamfer 12 of the rotor teeth 7 to the permanent magnets. The farther the distance of the permanent magnets 8 to the stator teeth 3 is selected, the smaller should be the width of the slot openings 18 on the stator, since the steepness of the bevel 12 of the rotor teeth 7 to the permanent magnets should maintain a certain angle, so that the leakage flux can be kept low over the slot openings 10 of the rotor 2. The groove openings 10 on the rotor form the shape of an equilateral trapezoid, wherein the small base of the trapezoid is built to the respective groove of the rotor and the width of this base is kept smaller in the circumferential direction of the rotor as the height of the permanent magnets, and the larger base of the trapezoid is directed to the stator teeth 3, this width in the circumferential direction of the rotor is dependent on the width of the slot openings 18 of the stator and thus the width of the stator teeth 3 in the circumferential direction of the air gap, wherein the width of the slots of the rotor at the air gap is to be selected in that the highest efficiency can be achieved with such an electric motor by, in a rotor position to the stator, in which a permanent magnet is aligned centrally to a stator tooth and thus directed to this stator tooth in equal proportions two unlike excited rotor teeth, the Polhornspitze 16 'of the adjacent stator tooth with respect to the direction of rotation of the rotor as far away from the leading edge 14' of a rotor tooth of the unlike excited rotor teeth, that this distance in the range of double the size of the air gap.

The grooves 9 for receiving the permanent magnets 8 are preferably circular in shape at the bottom of the groove. By such a design of the grooves of the rotor, the previously magnetized permanent magnets 8 can be securely pressed into the grooves 9 without glue. Balancing disks, which are preferably provided with fan blades for cooling the stator winding, and can serve to secure the permanent magnets, can be arranged on the front sides of the rotor.

By a design of the stator according to Fig. 3 and 4, such a motor is particularly well suited for a draft ventilation, since the slot openings of the rotor and the gap from one coil to the respective adjacent coil of the stator winding is correspondingly large, and thus a very good cooling of the coil 4 can be done.

Fig. 3 shows a stand with a large width of the groove openings 18 of the grooves of the stator, wherein at a certain bevel 12 of the rotor teeth 7 to achieve a width of the groove openings 10 of the grooves of the rotor, which corresponds to half the width of a stator tooth 3, are Permanent magnets 8 corresponding sunk in the rotor, so that from this the distance between the permanent magnets 8 to the stator teeth 3 results. _ Q -

In addition, the rotor position is shown in FIG. 3, in which a rotor step is preferably ended, in each case the running edge 13 and the leading edge 14 of a respective adjacent pole field of the rotor, with respect to the direction of rotation of the rotor, approximately in the middle of the front stator tooth of the respectively adjacent unlike excited stator teeth.

Fig. 4 shows a stator with a reduced width of the slot openings 18 of the slots of the stator, wherein to achieve a width of the slot openings 10 of the grooves of the rotor, which corresponds to half the width of a stator tooth, the permanent magnets 8 are sunk so far in the rotor, that the required steepness of the chamfer 12 of the rotor teeth 7 to the permanent magnets, which is necessary for minimizing the leakage flux in the region of the slot openings 10 of the rotor is given. In addition, in FIG. 4, the completed rotor step is represented by reversing the winding phases, wherein the next run step is simultaneously initiated, and now the trailing edge 13 and the leading edge 14 of a respective adjacent unlike pole field of the rotor, with respect to the direction of rotation Runner, each aligned approximately centrally to the rear stator tooth of each adjacent unlike excited stator teeth.

From Figs. 3 and 4 it can be seen that the groove opening 18 of the grooves on the stand is variably interpretable, wherein the width of the groove opening 10 of the grooves 9 of the rotor 2 at the air gap 6 can be up to half the width of a pole pitch on the stand so that the leakage flux can be kept low over the slot opening 10 of the grooves 9 of the rotor, and In each rotor position, a high torque, and a high efficiency is achieved, and thus a maximum performance can be achieved with such an electric motor.

The stand can also have only three stator teeth.

Fig. 5 shows such a design. Each stator tooth 3 is wrapped by a coil 4, and thus each winding strand includes one coil each. The winding strands are placed during operation of the motor to a power source such that two adjacent stator teeth form unlike poles to each other. The stator teeth 3 are formed such that the width of the stator teeth to the air gap 6 is at least about three-fifths and at most about four-sixths of the width corresponding to the width of a stator tooth plus the width of a slot opening. Such a design of the stator tooth width is also advantageous in a different interpretation of the number of stator teeth on the stand for use.

The pole face of the rotor teeth 7 directed towards the air gap, as well as the nose 12 forming the chamfer 12, can also be designed to be arcuate, wherein the chamfer 12 to the permanent magnets can be formed both arcuately inwardly and arcuately outward. This design has the advantage that a particularly smooth transition of the rotor steps can be achieved by the one rotor step to the next rotor step, and thus the torque ripple and the pole sensitivity of the electric motor is further reduced. To apply the winding strands to a power source, a control electronics is associated with the electric motor. Fig. 6 shows a circuit arrangement of the electronic control device for commutation of the winding strands. The winding strands are each connected at one end to a transistor-equipped half-bridge 20 and connected in star with the other end. The transistors 21 are associated with a control device 22.

The detection of the rotor position can be done with the known means, or the determination of the switching time of the winding strands is determined electronically and thus takes place sensorless.

Claims

claims

1. Electronically commutated electric motor with a stator (1) with stator teeth (3), which are each looped by a coil (4), and with a rotor (2) with rotor teeth (7) formed by a plate (9) provided with laminations. and with permanent magnets (8) in a collector arrangement, and the height of the permanent magnets (8) is designed smaller than half the width of a stator tooth (3), wherein the ratio of the stator teeth to the rotor teeth corresponds to 0.75: 1, and connectable to a power source electronic control device for commutating the phase windings of the electric motor, characterized in that to reduce the stray flux via the slot opening (10) of the grooves (9) of the rotor (2) the width of the slot opening (10) up to half the width of a pole pitch corresponds to the stator, and the rotor teeth (7) at the air gap in each case to the permanent magnets (8) are provided with a chamfer (12), so that the slot opening (10) of the Grooves (9) of the rotor (2) each having the shape of an equilateral trapezoid, wherein the bevel (12) to the permanent magnets (8) and the distance of the permanent magnets (8) to the stator teeth (3) are formed such that the width the slot opening (10) of the grooves (9) of the rotor (2) at the air gap in dependence on the width of the slot opening (18) of the slots of the stator and the width of the stator teeth (3), so that in a rotor position to the stator, at in that a permanent magnet of the rotor and thus two unevenly excited rotor teeth are aligned in the middle to form a stator tooth, the pole tip 16 'of the adjacent stator tooth is preferably so far away from the leading edge (14') of one rotor tooth that this distance is in the range of twice the size of the air gap.

2. Electronically commutated motor according to claim 1, characterized in that the rotor teeth (7) with a permanent magnet to the (8) forming the nose (11) are chamfered, and the width of the slot opening (10) of the grooves (9) of the rotor ( 2) in the region of the permanent magnets (8) is kept smaller than the height of the permanent magnets.

3. Electronically commutated motor according to claim 1, characterized in that the chamfer (12) of the rotor teeth (7) may be variably arcuate, wherein the arcuate taper (12) may be directed inwardly or outwardly.

4. Electronically commutated motor according to claim 1, characterized in that the width of the slot opening (18) of the grooves of the stator is variably interpretable, wherein the greater the distance of the permanent magnets (8) is selected to the stator teeth (3), the width of Groove opening (10) of the grooves (9) of the rotor at the air gap is determined to be larger, and the width of the slot opening (18) of the grooves of the stator is kept smaller.

5. Electronically commutated motor according to claim 1, characterized in that the grooves (9) of the rotor for receiving the permanent magnets (8) are preferably formed circular on the groove base, and by the corresponding design of the grooves (9), the permanent magnets in the grooves einpressbar are.

6. Electronically commutated motor according to claim 1, characterized in that arranged on the end faces of the rotor balancing discs also for securing the Permanent magnets serve, and can be provided for cooling the stator winding with fan blades.

7. Electronically commutated motor according to claim 1, characterized in that for a draft ventilation of the electric motor, the gap is selected from the one coil to the respective adjacent coil on the stator and the distance of the permanent magnets of the rotor to the stator teeth correspondingly large.

8. electronically commutated motor according to claim 1, characterized in that during the completion of a rotor step, the trailing edge (13) and the leading edge (14) of a respective juxtaposed unlike pole field of the rotor (2), with respect to the direction of rotation of the rotor , approximately centered to the front stator tooth of each adjacent unlike excited stator teeth is, and by reversing the winding strands of the next run step is initiated, and the outgoing edge (13) and the leading edge (14) of a respective adjacent unlike pole field of the rotor (2 ), in relation to the direction of rotation of the rotor, is now approximately centrally located to the rear stator tooth of each adjacent unlike excited stator teeth.

9. Electronically commutated motor according to claim 1, characterized in that the stator has three stator teeth and each winding strand each include a coil, wherein the stator teeth are formed such that the width of the stator teeth at the air gap at least three-fifths and at most four-sixths of the width is equal to the width of a stator tooth plus the width of a slot opening of the stator.

10. Electronically commutated motor according to claim 1, characterized in that the laminated core (15) of the stator (1) is held so that the rotor (2) has a moderately niesäßig large diameter, and for this purpose the stator teeth (3) with narrow Pole horns (16) are provided, and the yoke (17) is designed to be very narrow on the laminated core of the stator, so that in each case for receiving the coil (4) on the stator tooth, the required space is available.