WO2009068356A1 - Electric machine - Google Patents

Abstract

The invention relates to an electric machine, in particular an electrically excited claw pole generator (10) for motor vehicles, having a multi-phase stator winding (18), which has at least partial windings that are connected into five-phase series and/or star connections and are preferably interconnected in a hybrid circuit with partial windings of other strands partly in series, partly in star connections. The result is that the power output of a generator can be largely adapted to the demand at high and low rotational speeds, resulting in clear flexibility of the power output of the machine despite an identical number of conductors in each groove (15) of the machine.

Description

 description

title

Electric machine

State of the art

The invention relates to an electric machine according to the preamble of the independent claim, as it has become known for example from EP 1 244 194 Bl. This document discloses a method of manufacturing an alternator for vehicles having a multipole rotor and a stator whose three-phase winding is divided into sub-windings, which can be selectively connected to a star-delta arrangement in order to achieve performance-related optimization of the machine depending on the application, in particular speed-dependent. Such a three-phase interconnection generates a considerable magnetic noise and the harmonic content in the air gap field causes increased eddy current losses, which lead to higher winding temperatures in the rotor winding and reduce the exciter current and thus the output power in an electrically excited machine. In addition, the ripple in the output voltage of a machine operating as a generator is increased. Disclosure of the invention

The electrical machine according to the invention with the features of the independent claim has the advantage that with a variety of interconnection options in series, star or mixed circuit through the five-phase structure of the machine over a three-phase machine, the aforementioned disadvantages are largely avoided. In addition, the distribution of the winding strands of the stator in at least ten

Partial windings the advantage that a basic version of the stator winding is available, which always has the same number of conductors per groove, regardless of the size of the machine and, for example, the leakage flux compensation. The desired power characteristic is then adjusted via the ratio of the star-shaped coil components to the series-connected coil components. The magnetic noise of the machine can be further reduced by a higher number of partial windings with different phase position.

The measures listed in the dependent claims advantageous refinements and improvements of the independent claim arrangement are possible.

It is particularly advantageous if the largest possible number of partial windings of the stator winding in a mixed circuit partly connected in series and partly in

Star circuit can be operated with partial windings of other strands, because this with the same basic circuit many variations in terms of optimizing the power output at different sizes and result in different operating conditions. With regard to the manufacturing effort, however, it is expedient if the number of partial windings is limited to the number of partial strands. In this case, preferably five inner and five outer sub-strands are formed, wherein the five inner sub-strands are connected in series and the five outer sub-strands are connected in star connection to the connection points of the inner sub-strands. Such a symmetrical structure causes less harmonics and thus reduces the magnetic noise of the machine. The

Dividing into five inner and five outer sub-strands leaves enough design options in terms of power adaptation of the machine to the particular application by the number of turns, or the number of conductor segments per groove, the inner and outer sub-strands are more varied in the direction of series connection or star connection.

As a particularly advantageous Verschaltungsart for the inner sub-strands, a circuit in the manner of a

Drudenfußes (pentagram) proven, because in this case in the range of higher speeds, the increase in performance is clearly pronounced and at the same time by the operated in star connection outer sub-strands, even at low speeds sufficient power is available.

On the other hand, the interconnection of the inner partial strands as a pentagon offers the advantage of a higher one

Provision of power in the range of low speeds with simultaneously satisfactory power output at high speeds. The ratio of the number of turns of the inner partial strands and the outer partial strands in both circuit variants is preferably in the range between 0.5 and 2, in particular at 1. Further details and advantageous embodiments of the invention will become apparent from the dependent claims and from the description and illustration of the embodiments. Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Show it:

1 shows a longitudinal section through a

Alternator with claw pole rotor for motor vehicles,

2 shows a circuit diagram of a five-phase stator with a winding arrangement of the inner sub-strands as a Drudenfuß with star-shaped outer winding strands,

FIG. 3 shows a circuit diagram of a five-phase stator in an arrangement as a five-stranded inner ring with a star-shaped outer winding part

FIG. 4 shows a cross section through two stator slots with straight sections of the conductor segments in the slots;

FIG. 5 shows a detail of a stator of an electrical machine with conductor segments in an annular laminated core shown as a development, Figure 6 is a representation of the power output of an electric machine with different numbers of turns of Drudenfuß, or as star connected sub-strands and

Figure 7 is a representation of the output of an electric machine with different numbers of turns in the pentagon, or in the star connected sub-strands.

Embodiments of the invention

In Fig. 1 is a section through an alternator 10 for motor vehicles is shown. This has inter alia a two-part housing 13, which consists of a first bearing plate 13.1 and a second bearing plate 13.2. The bearing plate 13.1 and the bearing plate 13.2 take in a stand 16, with an annular laminated core 17, in the inwardly open and axially extending grooves 15, a stator winding 18 is inserted. The annular stator 16 surrounds with its radially inwardly directed surface an electromagnetically excited rotor 20, which is designed as a claw-pole rotor. The rotor 20 consists, inter alia, of two claw-pole plates 22 and 23, on the outer circumference of which claw-pole fingers 24 and 25 extending in each case in the axial direction are arranged. Both claw pole boards 22 and 23 are arranged in the rotor 20 such that their axially extending claw pole fingers 24, 25 alternate at the periphery of the rotor 20 as N and S poles. This results in magnetically required claw pole spaces between the oppositely magnetized claw pole fingers 24 and 25, which are slightly oblique to the machine axis because of the tapering to their free ends Klauenpolfinger 24 and 25.

The rotor 20 is rotatably supported in the respective end shields 13.1 and 13.2, respectively, by means of a shaft 27 and one respective rolling bearing 28 located on each side. It has two axial end faces, on each of which a fan 30 is attached. These fans 30 essentially consist of a plate-shaped or disk-shaped section, starting from the fan blades in a known manner. These fans 30 serve to allow an air exchange between the outside and the interior of the electric machine via openings 40 in the end shields 13.1 and 13.2. These are the

Openings 40 are provided at the axial ends of the end shields 13.1 and 13.2, via which 30 cooling air is sucked into the interior of the electric machine by means of the fan. This cooling air is accelerated radially outwards by the rotation of the fans 30, so that they can also pass through the cooling-air-permeable winding heads 45 on the drive side and 46 on the electronics side. This effect cools the windings. The cooling air takes after passing through the winding heads, or after the flow around this winding heads a path radially outward through openings not shown.

In Figure 1 on the right side there is a protective cap 47, which protects various components against environmental influences. Thus, this protective cap 47 covers, for example, a slip ring assembly 49, which supplies a field winding 51 with exciting current. Around this slip ring assembly 49 around a heat sink 53 is arranged, which acts as a positive heat sink here. When so-called negative heat sink acts the bearing plate 13.2. Between the end plate 13.2 and the heat sink 53, a connection plate 56 is arranged, which in the bearing plate 13.2 attached minus diodes 58 and not shown in this illustration plus diodes of a rectifier 19 in the heat sink 53 in the form of a bridge circuit interconnects.

FIG. 2 shows a five-phase claw-pole generator 10 on the basis of its circuit diagram. The stator winding 18 is composed of ten partial windings, which form five inner phases forming partial strands 7Oi to 74i and five outer phase forming partial strands 70a to 74a. The five inner sub-strands 7Oi to 74i are connected to a basic circuit as a five-pronged Drudenfuß (pentagram), wherein each interconnected in the connection points 80 to 84 inner sub-strands enclose an angle α of approximately 36 ° and have a number of conductors X per groove. At the connection points 80 to 84 of the Drudenfußes each outer phase-forming sub-string 70a to 74a connects in a star shape, each of the outer sub-string 70a to 74a has the same phase position as one of him directly connected to a connection point 80 to 84 inner sub-strands 7Oi to 74i. In the illustrated embodiment, the sub-strands having the same reference number each have the same phase position, that is to say, for example, 70a and 7Oi. These partial strands with the same electrical phase angle are each in the same grooves 15 of the stator 16. The total number Z of conductors in a groove results from the number of conductors X of the inner sub-string and the number of conductors Y of the in-phase outer sub-string. The ratio of the number of conductors X / Y should be in the range between 0.5 and 2, wherein preferably the conductor numbers of the inner sub-string and the in-phase outer sub-string are the same and this also have the same number of conductors as each of the remaining sub-strands.

In detail, the sub-strands of the stator winding 18 are connected as follows: The inner sub-string 7Oi is on

Connection point 80 is connected to the outer sub-string 70a and the inner sub-string 71i. The inner sub-strand 71i is connected at its opposite end at the connection point 81 with the outer sub-strand 71a and the inner sub-strand 72i. The inner sub-branch 72i is connected at its opposite end at the connection point 82 with the outer sub-strand 72a and the inner sub-strand 73i. The inner sub-branch 73i is connected at its opposite end at the connection point 83 with the outer sub-line 73a and inner sub-line 74i. The inner sub-line 74i is connected at its opposite end at the connection point 84 with the outer sub-line 74a and the inner sub-line 7Oi. The inner sub-strands 7Oi to 74i thus form a series circuit as a Drudenfuß.

The connection points 80 to 84 of the inner partial strands 7Oi to 74i are preferably axially on or adjacent to the electronics-side winding 46 of the stator 26 in order to realize the shortest possible Verschaltungswege. For this purpose, the connection wires of the inner sub-strands of a connection point to be interconnected emerge in the circumferential direction of directly adjacent grooves 15. The outer winding ends of the outer sub-branches 70a to 74a are connected to a B10 bridge rectifier 19, which is composed of five minus diodes 58 and five plus diodes 59. On the DC voltage side, the bridge rectifier 19 is connected in parallel with a voltage regulator 26 which, by influencing the current through the exciter winding 51 Voltage of the claw pole generator 10 regulates. The electrical system of the machine is shown schematically by a battery 31 and a consumer 32.

FIG. 3 shows the circuit diagram of a five-phase claw-pole generator 10 whose five inner phase-forming partial windings, which at the same time form the inner five partial lines 7Oi 'to 74i', are connected to a basic circuit as a five-phase ring or a pentagon. The partial windings meeting in the connection points 80 'to 84' form an angle α of approximately 108 ° el and are connected there to five outer star-shaped partial strands 70a 'to 74a'. The entirety of the inner and outer sub-strands forms the stator winding 18, wherein the outer sub-strands do not have the same phase position as the interconnected with them in the connection points 80 'to 84' inner sub-strands. However, the designations of the individual partial strands are chosen such that even with this interconnection inner and outer partial strands with the same number are in phase and lie in the same groove, for example the inner partial strand 7Oi 'and the outer partial strand 70a'. The inner sub-strands in turn have a number of conductors X, the outer sub-strands a number of conductors Y and the total number Z of a phase in a groove in turn corresponds to the sum of the conductor numbers X and Y of the in-phase sub-strands, wherein the ratio of the number of conductors X / Y again between 0.5 and 2, preferably 1.

In detail, the sub-strands of the embodiment in FIG. 3 are interconnected as follows: The inner sub-strand 7Oi 'is connected at the connection point 82' to the outer sub-strand 72a 'and the inner sub-strand 73i'. The inner one Sub-strand 73i 'is connected at its opposite end at connection point 80' to outer sub-strand 70a 'and inner sub-strand 71i'. The inner sub-string 71i 'is connected at its opposite end at the Verschaltungspunkt 83' with the outer sub-string 73a 'and the inner sub-string 74i'. The inner sub-string 74i 'is connected at its opposite end at the connection point 81' with the outer sub-string 71a 'and the inner sub-string 72i'. The inner sub-string 72i 'is at its opposite end on

Verschaltungspunkt 84 'connected to the outer sub-string 74a' and the inner sub-string 7Oi '.

The connection points 80 'to 84' are in turn axially on or next to the electronics side winding head 46 for the realization of short Verschaltungswege. For this purpose, in the interconnection according to FIG. 3, the respective conductors of the inner sub-strands of a connection point to be interconnected emerge from grooves spaced apart in the circumferential direction by three slot pitches. The outer winding ends of the outer sub-strands 70a 'to 74a' are connected to the bridge rectifier 19, which in turn is composed of five minus diodes 58 and five plus diodes 59. On the DC voltage side, the bridge rectifier is in turn connected in parallel with a voltage regulator 26 for regulating the current through the field winding 51 of the generator 10 and the vehicle electrical system connected to the generator is represented by a vehicle battery 31 and a consumer 32.

In both circuit variants according to FIGS. 2 and 3, it is basically also possible to realize non-integer number of conductors X and Y per slot when the inner and outer winding sub-strings are not full Circuits around the annular laminated core 17 of the stator 16 include, but for example, the inner winding sub-strands two and a half times and the outer winding sub-strands circulate one and a half times. The total number Z of conductors per groove of the inner and outer

Winding sub-strands, which are associated with an electrical phase, is in this case also 4. This allows a much finer resolution in the adaptation of the stator connection to the desired output power curve.

Figure 4 shows a partial section through the laminated core 17 of the stator of a Klauenpolgenerators in the region of two grooves 15. The illustrated stator winding has 4 conductors 60 in each groove 15, wherein the groove layers are designated from radially outside to radially inside with 1 to 4. The narrow sides of the conductors 60c and 60g, the interconnection of which is explained in more detail with reference to FIG 5, are arranged with their narrow sides opposite each other and with their broader sides in each case opposite the walls of the groove 15. The grooves are lined with an insulation 29, which usually consists of a rectangular, usually multi-layer insulation material. Due to the multi-layered construction, the greatest possible adhesion to the annular laminated core 17 and the lowest possible adhesion to the adjacent conductor segments 60 can be achieved, so that they can be more easily introduced into the groove. The ends of the insulation 29 are slightly spaced in the region of the slot opening, but in other embodiments these ends may also overlap one another.

FIG. 5 shows a detail of the stator 16 with the laminated core 17 and the stator winding 18 constructed of conductor segments 60. In the use of such Conductor segments each form two full segments one turn of the stator winding 18, so that there are just total numbers of conductors Z per groove, so for example 2, 4, 6, etc. In the present case, each four conductor segments are in a groove 15. Die Gesamtverschaltung der die

Partial windings, or the partial strands forming conductor segments has already been discussed with reference to Figures 2 and 3, wherein the total number of partial windings and the total number of partial strands is 10 each. The number of partial windings can also be selected to be larger, in which case several partial windings are interconnected in each case according to the desired turns ratio between the inner and outer partial strands to form a partial strand.

In the figure, the side portions engaged in the grooves 15 are designated 60c and 60g. These are arranged axially in four radial groove layers, as shown in FIG. 4, so that only the two outer winding layers are visible in the wavy stator winding 18 shown in FIG. The inner, non-visible winding layers 3 and 4 are identically constructed and offset in each case by two radial layers inwards. Each conductor segment 60 consists of several sections, which are designated 60a to 60i. In this case, a shorter connecting portion 60a or 6Oi extends radially outwards and serves for contacting radially adjacent sections of successive conductor segments. The first connection section 60a merges into a first inclined section 60b, which connects the connection section 60a to a first axially aligned section 60c of the conductor segment 60 that is inserted in a groove 15. The section 60c then merges into a second inclined section 6Od and this in turn into a bending section 6Oe, which leads over a further inclined portion 6Of and the axially aligned, in a spaced by five groove pitch groove 15 portion 60g and another inclined portion 60h to the connecting portion 6Oi, which in turn is behind a connecting portion 60a. In principle, however, each conductor segment 60 consist of several turns.

Each conductor segment 60 is divided into two radial layers, wherein the first connection section 60a, the first inclined section 60b, the first straight section 60c inserted in the groove 15, and the second inclined section 6d are in the same radial layer. The sections 6Of, 60g, 60h and 6Oi lie in a second radial layer, which is connected to the first radial layer via the bending section 6Oe. In the arrangement shown in Figures 4 and 5, the conductor segments are in the groove layers 1 and 2, and 3 and 4. Alternatively, it is possible to build the stator winding 18 of conductor segments which connect the groove layers 1 and 3, and 2 and 4 or optionally also the groove layers 1 and 4, or 2 and 3. The distance of five slot pitches between the conductors 60c and 60g corresponds to the selected five-phase design.

On the electronics winding side 46 each an outer conductor segment encloses an inner conductor segment. The outer conductor segment 60 lies in the groove layers 1 and 4. According to well-known winding schemes all grooves 15 of the stator 16 are each with winding sections 60 electrically in phase sub-strands 7Oi to 74i and 70a to 74a, or 7Oi 'to 74i' and 70a 'to 74a 'equipped. The partial strands are obtained by splitting a conductor segment 60 or by special conductor segments with only one axially aligned portion 60c and 60g in the groove 15, which then realize 45 connections of the partial strands on the bending side of the winding head. The position of the terminals of the electrically in-phase windings automatically results in the number of conductors of the inner sub-string and the outer sub-string and the sequence of conductor segments 60, a wave-shaped stator winding 18 is formed.

In Figure 5, a portion of a wave winding is shown, but instead the stator winding 18 may be formed as a loop winding, for example in the form that conductor segments 60, the groove layers 1 and 4, and 2 and 3 occupy. Alternatively, the conductor segments at a

Loop winding connect the groove layers 1 and 3, and 2 and 4 respectively.

In the figure, a section of a stator winding 18 for a stator 16 with 80 slots and 10 phase-forming

Sub-strands for an electrically excited rotor 20 with 16 Klauenpolfingern 24 shown. However, the invention is not limited to this embodiment. Instead, the stator 16 could, for example, also be designed with 60 slots and 10 phase-forming sub-strings for an electrically excited rotor 12 with 12 poles.

For the preparation of the conductor segments 60 is based on a round wire or a profile wire, which is first brought into a U- or V-shaped configuration. In this preform, the radial distances of the two later in the grooves 15 inlets 60c and 60g of the conductor segments 60 are already given, however, these sections have no distance in the circumferential direction. This one will by nutweisweiser twisting the sections 60c and 60g in the circumferential direction. The resulting second precursor in the production of the conductor segments 60 is inserted into an annular laminated core 17 axially in the grooves 15. In order to complete the sub-strands, the connecting portions 60a and 60i are bent toward each other in layers in the circumferential direction and then electrically connected together by soldering or welding. The bending portions 6Oe and the connecting portions 60a and 60i are formed by a suitable tool.

Figure 6 shows a diagram of the output power of the claw pole of a motor vehicle, in this case at a rated voltage of 12 volts the output current I in amperes depending on the generator speed n in revolutions per minute, the five-phase stator winding in the curve A with all partial windings as Drudenfuß is connected, in the curve E with all partial windings as a star and in the intermediate curves B, C and D in a mixed circuit. In the circuit B, three of four conductor segments 60 of each groove 15 of the Drudenfußschaltung the inner partial strands 7Oi assigned to 74i, in the curve C, the conductor segments are evenly distributed with two segments and in the curve D is only one conductor segment in the inner

Connected sub-strands as Drudenfuß and 3 of a total of 4 conductor segments in the outer sub-strands 70a to 74a in star.

From the diagram it can be seen that the

Drudenfußschaltung brings significant performance advantages at high speeds, while at low speeds, the star connection already at much lower speeds than the Drudenfußschaltung a performance decrease allows. The distribution of the total number Z of conductor segments per groove 15 can thus be varied according to the application to achieve an optimal power output by the conductor numbers of the inner sub-strands and the outer sub-strands are each varied between 0 and 4. The illustration applies to a claw pole generator 10 of a motor vehicle, which has a generator speed of approximately 1 800 rpm when the internal combustion engine is idling, so that the underlying generator speeds are practically of no importance.

FIG. 7 shows, in a manner analogous to FIG. 6, the power output as output current I in amperes in turn dependent on the generator speed n in rpm for one

Generator, whose partial windings and partial strands are operated either as pentagon, star or in mixed circuit. Analogous to the representation in FIG. 6, the conductors in curves A, B, C, D and E are also divided in FIG. 7, specifically in curve A with all four

Conductor segments in the inner sub-strands 7Oi 'to 74i', in curve B with three conductor segments in the inner and a conductor segment in the outer sub-strands, in curve C with two conductor segments in the inner and outer sub-strands, in curve D with a conductor segment in the inner sub-strands and three conductor segments in the outer sub-strands and finally in curve E with all four conductor segments of each groove 15 in the outer, star-connected conductor segments 70a 'to 74a'. The power curves show that the output power between the rated speed of the generator of 6000 rpm and the idling of the internal combustion engine with a generator speed of about 1800 rpm is widely adapted to the use of the generator and therefore also in this case Circuit variant allows a flexibility of the output characteristics despite identical total conductor number Z of four conductors per groove can be produced. Even with this circuit variant, the characteristic curve does not play any role in the speed range below 1800 rpm. Compared to the curve in Figure 6, however, a significantly flatter course of all curves in the upper speed range can be seen, which means that the output power over a large speed range is very uniform and idle the engine at about 1800 U / min of the generator almost no difference between the Circuit variants exists.

In all the circuit variants shown in FIGS. 6 and 7, it can be seen that the pure star connection has power disadvantages compared to the series connections. Besides, it has noise disadvantages. Their advantage lies in the lower number of conductors required per slot in order to realize a specific performance characteristic. By choosing the circuit variant, the respective desired operating mode can be realized.

Claims

claims Characterized in that the stator winding has at least ten partial windings, which are connected to a five-phase series and / or star connection , 2. Electrical machine according to claim 1, characterized in that partial windings of the stator winding (18) for operation in mixed circuit with partial windings of other strands (70-74) are interconnected partly in series and partly in star connection. 3. Electrical machine according to claim 1 or 2, characterized in that the stator winding (18) with five inner (70i-74i) and five outer sub-strands (70a-74a) is formed, wherein the five inner sub-strands are connected in series and the five outer sub strands in Star connection to the connection points (80-84) of the inner sub-strands are connected. 4. Electrical machine according to one of the preceding claims, characterized in that in Series circuit operated inner sub-strands (70i-74i) are connected in the manner of a Drudenfußes (pentagram). (Figure 2) 5. Electrical machine according to claim 4, characterized in that the series-operated inner sub-strands (70i-74i) in the Vebindungspunkten (80- 84) of the Drudenfußes are connected at an angle of approximately 36 ° el. 6. Electrical machine according to one of the preceding claims, characterized in that the one star forming outer partial strands (70a-74a) each have the same phase position as one of the two directly associated with them inner sub-strands (70i-74i). 7. Electrical machine according to one of claims 4 to 6, characterized in that each at a connection point (80-84) interconnected conductor segments (60) of the inner sub-strands (70i-74i) are arranged on the stator circumference in adjacent grooves (15). 8. Electrical machine, according to one of claims 1 to 3, characterized in that the series-operated inner sub-strands (70i'-74i ') are interconnected as a pentagon. (Fig. 3) 9. Electrical machine according to claim 8, characterized in that the series-operated inner sub-strands (70i'-74i ') in the connection points (80' -84 ') of the pentagon at an angle of about 108 ° el. are interconnected. 10. Electrical machine according to claim 8 or 9, characterized in that in each case at a connection point (80 '-84') interconnected conductor segments (60) of the inner sub-strands (70i'-74i ') are offset by three slot pitches on the stator periphery. 11. Electrical machine according to one of claims 8 to 10, characterized in that the star forming outer partial strands (70a'-74a ') each have the same phase position as one of the two with an adjacent connection point (80' -84) interconnected inner Partial strands (70i'-74i '). 12. Electrical machine according to one of the preceding claims, characterized in that the conductor segments (60) of the inner (70i-74i, 70i'-74i ') and outer (70a-74a; 70a' -74a ') partial strands with the same phase position each lie in the same groove (15) of the stator (16). 13. Electrical machine according to one of the preceding claims, characterized in that in each groove (15) of the stator (16) a total of four conductor segments of the inner (70i-74i; 70i'-74i ') and / or outer sub-strands (70a-74a ; 70a'-74a ') lie. 14. Electrical machine according to one of the preceding Claims, characterized in that the free ends of the outer sub-strands (70a-74a, 70a '-74a') via a five-phase rectifier bridge circuit (19) to a DC voltage network (31,32) are connected. 15. Electrical machine according to one of the preceding claims, characterized in that the Connection points (80-84) of the partial strands (70-74) lie in the region of the electronics-side winding head (46) of the stator winding (18). 16. Electrical machine according to one of the preceding claims, characterized in that the ratio X / Y of the number of turns (X, Y) of the inner sub-strands (70i-74i; 70i '-74i') and the outer sub-strands (70a-74a; 70a '-74a') are between 0.5 and 2, preferably at 1.