WO2010063546A1 - Hybrid-energized electrical machine with a pole-changing rotor - Google Patents

Abstract

The invention relates to a hybrid-energized electrical machine (10) having a stationary stator (16) which has a stator winding (18), and having a rotor (20) which has, over its circumference in a predefined order, a plurality of poles which are energized by permanent magnets (25) and electrically energized by a field coil (29), wherein the pole number can be changed by means of the intensity and direction of the field current in the field coil. For simple, robust and cost-effective construction of the pole-changing rotor (20), the invention proposes that the field coil (29) is designed as an annular coil which is arranged around the machine axis (x).

Description

 description

title

Hybrid electric machine with pole-changing rotor

State of the art

The invention relates to a hybrid-excited electric machine with a stationary stator and a pole-changing rotor according to the preamble of patent claim 1.

Such electrical machines are suitable as synchronous machines both for operation on a fixed three-phase network as a generator and as an electric motor. Furthermore, such machines are suitable in generator mode for controlling the induced voltage of a polyphase stator winding, as required for example in vehicle electrical systems. The poles are on the circumference of the rotor partly permanent magnetic and the other part electrically excited.

From US Pat. No. 7,408,280 B2 it is known to arrange a rotor lamination stack between two pole plates fixed to a rotor shaft in a vehicle generator on the rotor in the manner of a Lundell rotor, wherein the two pole plates each have on their inside a cylindrical projection, which respectively forms a half of a Polkernes on which an annular coil is attached to the field excitation of the rotor. In Bleckpaket here additionally tangentially magnetized permanent magnets are used, which amplify the electrically excited poles. However, this machine is not polumschaltbar and thus limited in operation as a variable generator can be used.

A similar electric machine is known from the publication US 2006/01 1 38 61 A1, where there the annular rotor laminated core is placed on the outer circumference of the two mounted on the machine shaft pole pieces. Also There, the electric field generated by the toroidal coil is amplified by tangentially magnetized permanent magnets whose magnetic stray fields are damped by additional magnets on the circumference of the two pole plates. This machine can not be switched over again, so its range of application is also limited.

From the document US 2006/01 1 92 06 A1, finally, a hybrid-excited rotor of an electric machine is known, which is designed to be switchable by a reversal of the electrical excitation. The poles of the rotor are separated at its outer periphery by grooves, so that alternate at the higher pole tooth, the north and south poles, whereas at the smaller number of poles several adjacent poles each form a common south or north pole. While the permanent magnets are each used there in a punched window below a pole, individual coils are wound around punched pole teeth of the rotor for electrical excitation of the rotor.

In this case, high fly forces act on the excitation coils during operation and the rotational speed resistance is correspondingly limited. Furthermore, there is needed for the preparation of the excitation coils a complicated and complex winding process, whereby further the copper filling factor at the pole teeth of the rotor is relatively low.

With the present invention, the aim is to equip a synchronous electric machine with a hybrid-excited, pole-changing rotor with an excitation coil which is easy to manufacture and mount in order to realize a rotor having a rotational speed which is as simple and robust as possible.

Disclosure of the invention

In electrical machines with a hybrid-excited pole results with the characterizing feature of claim 1, the advantage that with the execution of the exciter coil as a toroidal high copper filling factor of the rotor achieved and thus a strong and homogeneous electric field can be generated in the rotor. Furthermore, the arrangement of the annular coil around the machine axis results in a high rotational speed stability of the rotor and thus a cost-effective, simple and robust rotor structure. In the simplest way while the exciter coil is pre-wound. The measures listed in the dependent claims, advantageous refinements and developments of the features specified in claim 1.

In order to produce the parts of the rotor in the simplest possible way and to assemble, it is proposed to set up or wind the exciter coil on a cylindrical pole core 31, on whose end faces in each case a pole plate is arranged, via which the electrically excited permanent magnet flux to the poles on the rotor circumference to be led.

The pole core can be integrally formed in each case half of the two pole plates or produced in one piece with the machine shaft. Preferably, however, it is proposed to fix the pole core and the pole plates as separate, easily manufacturable parts on the machine shaft.

For a simple and robust construction of the rotor, it is expedient if the exciter coil is concentrically surrounded by an annular rotor core stack, in which the preferably radially magnetized permanent magnets are used for the magnetic excitation of the rotor. To achieve the best possible magnetic connection between the pole plates and the rotor laminated core, it is proposed that the two pole plates rest with radially outwardly directed flux conducting sections on the end faces of the rotor laminated core. In order to avoid magnetic short circuits, the flux conducting sections of one pole plate are expediently offset from the flux conducting sections of the other pole plate by at least one pole pitch of the higher number of poles of the rotor.

When using the electric machine as a three-phase alternator for motor vehicles, it is expedient for achieving low voltage and current ripple, low magnetic and mechanical vibrations and for noise damping and damping of an armature reaction when the hybrid-excited rotor cooperates with a stator carrying a five-phase stator winding whose five winding strands are connected in series to form a five-zig star, in which preferably one adjacent winding strands is skipped in each case. - A -

To achieve a high efficiency is proposed in a further development of the invention that are used between the electrically and the magnetically excited poles on the circumference of the rotor tangentially magnetized, pole-separating permanent magnets in the rotor core. Expediently, the tangentially magnetized permanent magnets are each arranged between two permanent magnetically excited poles or between a permanent magnet and an electrically excited pole or between two electrically excited poles.

For the use of the electric machine as a generator in motor vehicles, the excitation coil is expediently designed such that the output voltage of the stator winding is preferably adjustable by load and temperature dependent between a maximum value and the value zero by a change of strength and direction of the excitation current in the exciter coil. In this case, the rotor preferably has the higher number of poles in the normal generator operation of the machine, wherein the strength and direction of the excitation current is expediently to be chosen so that in cooperation with the permanent magnets on the circumference of the rotor approximately equally strong poles of alternating polarity occur.

For suppressing stray magnetic fluxes, it is further proposed that at least one of the two pole plates has a flux conducting region with a plurality of flux conducting sections, of which at least one contacts an electrically excited pole and preferably another pole which is excited by a permanent magnet.

Furthermore, the efficiency of the machine can be improved by axially inserting at least one iron core in the region of an electrically excited pole into the rotor laminated core in order to improve the conduction of the electrically excited field within the axially stacked lamellae of the blech package.

Furthermore, the rotor laminated core is expediently provided on the circumference in each case between two poles with a pole-separating groove. Below each magnetically excited pole of the rotor laminated core is expediently an approximately the pole width corresponding to wide window for receiving a punched radially magnetized permanent magnet. In addition, in a refinement of the invention in the rotor laminated core for receiving a tangentially magnetized permanent magnet to the magnetically and electrically excited poles, a radially aligned window is offset below a pole-separating groove.

In an expedient embodiment of the rotor, preferably two electrically excited poles of alternating polarity are arranged on the circumference of the rotor laminated core at a higher number of poles of preferably twelve poles between two permanent magnetically excited poles of alternating polarity. Such a pole sequence can also be realized on an eight-pole rotor.

However, if one wishes to be able to regulate the output voltage of the generator as quickly as possible in such machines, the number of electrically excited should be

Poles are more than twice larger than the magnetically excited poles. For this purpose, it is proposed in a further development of the invention that at the higher pole number of preferably twelve poles between two permanent magnetically excited poles of the same polarity preferably three electrically excited poles are arranged with alternating polarity.

A particularly good transition of the electrically excited magnetic flux from the two Polplatinen to the rotor laminated core can be achieved, that the Flußleitbereich is deposited on the outer circumference of the Polplatinen each by a shoulder of the Polplatinen, which rests on the inner circumference of the rotor core. The Flußleitbereiche the Polplatinen are advantageously separated from each other in the circumferential direction by a respective recess, the bottom of which is radially below the shoulder.

In order to support the flux excited by permanent magnet, it is also advantageous if the flux-conducting region of the pole plates is contacted with one of its flux-conducting sections radially below a permanent magnet with the end face of the rotor lamination stack.

Further, it is proposed to reduce magnetically caused noise of the machine that rotor laminated core over its outer circumference to the To provide Poland with at least one chamfer whose width is between the 0.05 and 0.7 times the width of a pole pitch of the higher number of poles and whose depth corresponds to 0.01 to 0.1 times the radial width of the annular rotor lamination.

Brief description of the drawings

The invention will be explained below by way of example with reference to the figures. 2 shows a circuit diagram of the generator with a bridge circuit of a five-phase stator winding in an arrangement as a five-pointed star, FIG. 3 shows an exploded view of a rotor according to the invention as the first embodiment.

Figure 4a, 4b shows the rotor of Figure 3 in front view with the electric

Reversal between twelve and four poles.

FIG. 5 shows in a diagram the course of the output voltage of the machine in generator operation as a function of the exciter current. Figure 6a shows a simplified view of the rotor in its axial extent and extent in the circumferential direction.

Figure 6b shows the annular rotor core in its radial extent and its extent in the circumferential direction.

FIG. 6c shows an alternative embodiment of the annular rotor laminations in its radial extent and extent in the circumferential direction.

FIG. 7 shows a sheet metal section for the joint production of the lamellae of FIG

Rotor and stator laminated core, Figure 8 shows an edgewise rolled annular rotor core in one

Side view, Figure 9 shows a fixing form of the annular rotor laminated core on a pole plate. FIG. 10 shows an exploded view of a rotor according to the invention as a second exemplary embodiment,

Figure 1 1 a, 1 1 b shows the rotor of Figure 10 in front view with the electrical reversal between twelve and six poles. Figure 12 shows an exploded view of a rotor according to the invention as a third embodiment.

13a, 13b show the rotor from FIG. 12 in the front view with the ectrical reversal control between twelve and four poles, and FIG. 13c shows a schematic representation of the development of the rotor from FIG. 12 with the electrical reversal from 12 to 6 poles.

Figures 14 to 21 show alternative solutions in a schematic representation of the rotor according to Figure 13c.

Embodiments of the invention

In Fig. 1 as an electric machine 10 according to the invention, an alternator for motor vehicles is shown in longitudinal section. This has inter alia a two-part housing 13, which consists of a first bearing plate 13a and a second bearing plate 13b. The bearing plate 13a and the bearing plate 13b take in a stator 16, with an annular stator lamination 17, in which inwardly open and axially extending grooves 19, a stator winding 18 is inserted. The annular stator 16, with its radially inwardly directed surface, surrounds a permanent-magnet and electromagnetic rotor 20, which is designed as a hybrid-excited rotor. Of the

Stator 16 acts in this case via a working air gap with the rotatably mounted in the stator 16 rotor 20. The rotor 20 has over its circumference in a predetermined sequence on several north poles N and south poles S, which are formed by polbildende permanent magnets 25, as well as by an excitation coil 29. In this case, the number of poles of the rotor 20 can be reversed depending on the strength and direction of an excitation current in the exciter coil 29. The exciter coil 29 is in this case designed as a ring coil about the axis x of the machine. Radially inside the exciter coil 29 is the pole core 31. The electromagnetically active part of the rotor 20 is bounded axially by two pole plates 22 and 23. These lead the electrically excited field from the pole core towards an annular rotor core 21. The annular rotor core 21 is preferably laminated in the axial direction. Radially inside the rotor laminated core 21, the exciting coil 29 is arranged. The transfer points between the respective pole plate 22, 23 and the rotor laminated core 21 are stepped in the region of its end faces 21 a, 21 b, in which at the radially outer region of the pole plates in each case one

Fluxing 39 is offset by a shoulder 39a of the pile boards, so that a larger transition surface to the rotor core 21 for the electrically excited field arises. The construction shown here, in which both a transfer of the electrically excited field in the radial and in the axial direction of the pole plate 22,23 in the rotor core 21 is possible, is particularly effective.

The rotor 20 is rotatably mounted in the respective end shields 13a and 13b, respectively, by means of a machine shaft 27 and one respective rolling bearing 28 located on each side of the rotor. 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 sheet metal 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 10 via openings 48 in the end shields 13a and 13b. For this purpose, the openings 48 are provided at the axial ends of the bearing plates 13a and 13b, via which cooling air is sucked into the interior of the electric machine 10 by means of the fan 30. This cooling air is accelerated radially outward by the rotation of the fans 30 so that they can pass through the cooling-air-permeable winding heads 50 on the drive side and 51 on the electronics side. By this effect, the winding heads 50, 51 are cooled. The cooling air takes after passing through the winding heads 50,

51, or after the flow around these winding heads 50, 51 a way 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 the exciting coil 29 with exciting current. Around this slip ring assembly 49 around a heat sink 53 is arranged, which acts here as a plus heat sink, are mounted on the positive diodes 59. As a so-called minus heat sink, the bearing plate 13b acts. Between the end shield 13b and the heat sink 53 there is arranged a connection plate 56, which connects negative diodes 58 and positive diodes 59 fixed in the end shield 13b in the heat sink 53 in the form of a rectifier bridge circuit 69 (see FIG.

2 shows the circuit diagram of the alternator 10, the stator winding 18 with five phase-forming winding strands 70, 71, 72, 73,

74 is executed. The five winding strands 70, 71, 72, 73, 74 are one Basic circuit as a five-pointed star (Drudenfuß) connected in series, with each interconnected in the prongs of the star strands enclose an angle of approximately 36 ° el., By each an adjacent strand is skipped. At the interconnection points 80, 81, 82, 83, 84 of the teeth of the five-pointed star, the rectifier bridge circuit 69 is connected. The winding strands are interconnected as follows. The winding sub-string 70 is connected to the winding sub-string 71 at the connection point 80. The winding strand 71 is connected to the winding strand 72 at its opposite end at the connection point 81. The winding strand 72 is connected to the winding strand 73 at its opposite end at the connection point 82. The winding sub-string 73 is connected to the winding strand 74 at its opposite end at the connection point 83. The winding strand 74 is connected at its opposite end at the connection point 84 with the winding strand 70. The Verschaltungspunkte are preferably axially on or adjacent to the electronics side winding 51 to realize the shortest possible Verschaltungswege. For this purpose, the respectively connecting wires of the winding strands 70, 71, 72, 73, 74 of a connection point 80, 81, 82, 83, 84 preferably emerge from grooves 19 which are directly adjacent in the circumferential direction. The connection points 80, 81, 82, 83, 84 of the winding strands 70, 71, 72, 73, 74 are connected to a separate bridge rectifier 69, which is composed of five minus diodes 58 and five plus diodes 59. On the DC voltage side, a voltage regulator 66 is connected in parallel, which regulates the voltage of the generator by influencing the current through the exciter coil 29 via its output 66a. In addition, the voltage regulator can also connect to the rectifier to measure the voltage drop across a diode and from this determine the current speed of the generator. The vehicle electrical system is represented schematically by the onboard power supply battery 61 and by the onboard power supply consumer 62. It is also possible to better control, the excitation coil 29 by means of four power amplifiers, which are connected to an H-bridge circuit to control. This makes it possible to impress in the excitation coil 29 and negative excitation currents. This results in advantages in terms of the power control behavior of the generator or with respect to the control speed, since for fast de-energizing, negative voltages can also be applied to the exciter coil 29. 3 shows the exploded view of a first embodiment of a hybrid-excited rotor 20. First, the individual components of the rotor 20 will be explained in more detail below, later will be discussed in more detail on the assembly.

The machine shaft 27 has at its one end a thread 36 for mounting a pulley. For fixing the pole core 31, or the pole plates 22, 23, a knurled region 37 is provided on the machine shaft 27. The machine shaft 27 preferably has a stop 38, which secures the Polplati- nen 22,23 and the pole core 31 in the axial direction. The machine shaft 27 further has axially extending grooves 38a in the area where the slip ring assembly 49 is later mounted. The grooves 38a serve to receive the connection conductors 29a between exciter coil 29 and slip ring assembly 49. The diameter of the machine shaft 27 in the region of the slip ring assembly 49 is reduced in this case. The machine shaft 27 is at least partially hardened.

The electronics-side pole plate 23 has a cylindrical hole for receiving the machine shaft 27 in the axial center. The transition point from the pole plate 23 to the rotor core 21 is stepped by means of a shoulder 39a, so that both an axial and a radial surface for the electrically excited field , Here, the transfer surfaces have not only the function of Ü transmission of the electrically excited field, but also the function of the radial or axial fixation and centering of the rotor core 21th However, it is also possible to produce the pole plates 22, 23 with only purely radial or axial transfer surfaces, however, additional measures for fixing and centering must then be made for this purpose, although the possible output power drops as the field is reduced by the latter Crossing area becomes smaller. The pole plate 23 shown here has two flux-conducting regions 39, which protrude radially from the cylindrical main body of the pole plate 23. Each of the flux guide regions 39 shown here extends over three poles P of the twelve-pole rotor 20, wherein the two outer poles each form an electrically excited pole of the rotor 20, so that two outer flux conducting sections 39e of each flux conducting region 39 each have an electrically excited pole P. animals, by abutting the front end side of the rotor core 21 lamination.

A mean flux-conducting section 39m of the flux-guiding regions 39 lies in each case in the rich of a permanent magnetically excited pole P on the front side of the rotor laminated core 21 at a radially further inwardly located point where it does not directly contact the pole-forming radially magnetized permanent magnet 25. This avoids that the field of the pole-forming radially magnetized permanent magnet 25 is shorted by the Polplatinen 22, 23. The

Field transmission takes place at each flux-conducting region 39 in the radial direction and in the axial direction into the rotor laminated core 21. The electronics-side pole plate 23 has a further function with respect to the drive-side pole plate 22. The terminals of the excitation coil 29 must be guided in the region of the gap in the circumferential direction between the two Flußleitbereichen 39 and the rotor core 21 lamination. For this purpose, additional embossments or grooves can be attached to the pole plate 23. The balancing of the rotor 20 is preferably carried out by bores in the region of the axial outer surfaces of the Polplatinen 22,23. The region of the radial or axial field transmission is preferably processed, i. overexcited. The drive-side pole board

22 is identical in construction to the electronics-side pole plate 23, but it is mechanically rotated by 90 °, in order accordingly to contact the not yet contacted by the electronics-side pole plate 23 electrically or magnetically excited pole of the rotor core 21. To avoid magnetic short-circuiting the Flußleitbereiche 39 of the Polplatinen 22, 23 in the circumferential direction by a respective recess 22a separated from each other, the bottom 22b is radially below the shoulder 39a.

The exciting coil 29 is wound in the circumferential direction, so that at the radially inner portion of the axial end surface and at the opposite radially outer portion of the axial end surface of the exciting coil 29 are the beginning, or the end of the exciting coil 29. The excitation coil 29 can be pre-wound in a bobbin, which consists of plastic or paper and produces an electrical insulation radially to the pole core 31 and axially to the pole plates 22,23. Preferably, the exciter coil 29 is also insulated radially in the direction of the rotor laminated core 21. This can be done by folding the plastic or paper insulation or by an additional insulating tape. The excitation coil 29 is preferably connected by impregnation with the surrounding insulation. The pole core 31 is provided with a cylindrical, axially extending hole 31a to receive the machine shaft 27 therein. The annular rotor core 21 is laminated in the axial direction with a thickness between 0.1 mm and 2.0 mm. Below 0.1 mm, the resistance of the rotor core 21 against centrifugal forces is too low. Above 2.0 mm, the reduction of the eddy current losses on the outer surface of the rotor 20 is no longer sufficient, so that the permanent magnets 24, 25 installed in the rotor can be damaged or demagnetized. The axial length of the rotor laminated core 21 corresponds to the axial length of the annular stator lamination 17, and is for a tolerance compensation up to. 2 mm longer than the annular stator lamination stack 17. The rotor lamination stack 21 has axially extending grooves 32 on the outer surface, which separate the rotor poles P from one another. Furthermore, in the rotor laminated core 21 axial, tangentially aligned, about the Polbreite correspondingly wide window 35 punched, in each of which a polbildendem radially magnetized permanent magnet 25 is used. Furthermore, axial, radially aligned windows 34 are punched out underneath pole-separating grooves 32 into which pole-separating permanent magnets 24 are used, which are magnetized tangentially. The rotor core 21 is held together by welds within the pole separating grooves 32. The welds are spaced in the circumferential direction preferably two pole pitches 2pt, wherein the pole pitch pt is defined in the electrically excited state, ie at the maximum number of poles. It can be provided to increase the speed stability welds after each pole pitch pt. It can be used instead of welds and rivets, or knobs.

The rotor laminated core 21 shown here has a total of twelve poles, wherein four of the poles are formed by radially magnetized permanent magnets 25 and eight poles are electrically excited. Thereby, the machine can be switched by means of the excitation coil 29 of twelve outwardly acting poles on four outward poles. In order to increase the performance of the system, the pole-separating tangentially magnetized permanent magnets 32 are inserted at the positions of the rotor core 21, at which the flux guide regions 39 of different polarity are located axially opposite each other. These can, in order to produce a low-cost variant also not be equipped. However, a leakage flux then forms in the window 34, which has a performance-reducing effect. The pole-separating permanent magnets 24 preferably have a rectangular cross-section. The pole-forming permanent magnets 25 preferably have a trapezoidal cross-section. The Rotor laminated core is constructed so that in the circumferential direction in each case a permanently excited north pole, an electrically excited south pole, a pole-separating permanent magnet, an electrically excited north pole, a permanently excited south pole, an electrically excited north pole, a poltrennender permanent magnet, an electrically excited south pole, a permanently excited north pole, an electrically excited

South Pole, a pole-separating permanent magnet, an electrically excited north pole, a permanently excited south pole, an electrically excited north pole, a pole-separating permanent magnet and an electrically excited south pole follow.

In the following, the assembly of the rotor 20 will be explained with reference to the exploded view of Figure 3. First, the electronics-side pole board 23 is aligned and pressed onto the machine shaft 29. Then, the pole core 31 is pressed onto the machine shaft 27. The excitation coil 29 is now either wound directly onto a coil carrier on the pole core 31 or mounted as a finished assembly on the pole core 31. Then the rotor laminated core 21 is pushed with the equipped permanent magnets 24,25 on the electronics-side pole plate 23. The permanent magnets 24, 25 are in this case e.g. fixed by resin or mechanical fuses. Then, the driving-side pole plate 22 is aligned and caulked on the machine shaft 27. Then, the fans 30, the electronics-side rolling bearing 28, and the slip ring assembly 49 are mounted.

Finally, the rotor 20 is balanced by bores in the pole plates 22,23.

The permanent magnets 24, 25 used are preferably made of rare earth magnet material NdFeB. The permanent magnet material preferably has a neodymium Nd-mass percentage greater than 10%, a mass percentage iron Fe of greater than 40%, a mass percentage copper Cu less than 2% and a mass percentage titanium Ti less than 1%. The Curie temperature of the permanent magnets is preferably above 200 ⁰ C. The remanence Bt is preferably above 1, 0 Tesla, the coercive force HcB is preferably above

700 kA / m. The permanent magnets 24,25 are preferably sintered, wherein the density of 7.0 g / cm ^Λ is greater. 3 The following preferred ranges apply to the dimensions within the rotor: Rotor outer diameter to the inner diameter of the annular rotor lamination packet 21 is between 1, 1 and 1, 25. The rotor outer diameter to the outer diameter of the pole core 31 is preferably greater than 1, 5; in particular, the value is between 1, 6 and 2.2. The Polkern know an axial length to the sum of the axial length of the Polplatinen 22,23 from 0.5 to 1, 5 on. The excitation coil preferably has a resistance between 1, 4 and 3.0 ohms for a 14V design. The pole core can also be integrally formed half on the axial inner surfaces of the Polplatinen. This has the advantage that then only an effective air gap between the Polplatinen in axial

Direction is present. The generator preferably has a pressure difference between the axial end surfaces of the rotor during operation, so that a cooling air flow is formed along the axially extending grooves 32 of the rotor lamination stack 21. Alternatively, holes may be formed in the rotor core, which allow this cooling air flow.

In Figure 4a, the occurring at the periphery of the rotor 20 pole sequence is shown, resulting in a current flowing through the excitation coil 29 excitation current Ie. Between the pole-separating tangentially magnetized permanent magnets 24 four pole-forming radially magnetized permanent magnets 25 are arranged on the rotor circumference, which cooperate with alternating radial polarity with the field generated by the excitation coil 29. As a result, upon excitation of the exciter coil with an exciter current Ie at the rotor circumference, there are twelve poles of alternating polarity.

FIG. 4b shows the state when the current direction in the excitation coil is reversed. As a result, the number of poles of the rotor 20 can be reversed, in which by reversing the detectable in Figure 4a electrically excited field Φ _{e of} the excitation coil 29, the polarity of the Polplatinen 22,23 and thus the electrically trained pole on the rotor circumference, which in Figure 4b by in brackets illustrated polarity is clarified. This results now in the rotor circumference a four-pole arrangement with alternating symmetrical polarity. The magnetic fields Φm of the pole-forming permanent magnets shown in FIG. 4b close over the pole plates or over the pole core. The drawn in Figure 4a magnetic fields Φm of the polbildenden

Permanent magnets 25 close on the rotor side within the rotor laminated core segment, consisting of the respective magnetically excited pole and the two adjacent electrically excited poles.

With the help of Figure 5 will now be explained in more detail that the output voltage

Inter alia, the stator winding 18 of the alternator 10 of Figure 1 by a change in the strength and direction of the excitation current Ie in the excitation coil 29 is preferably load- and temperature-dependent between a permissible maximum value and the value 0 can be regulated. In this case, over the time axis t of the excitation current Ie dependent course of the output voltage Ua of the machine 10 over half a revolution of the rotor 20 (180 ° mechanical) is shown. In the case of the twelve-pole alternating current stator winding 18, consequently, half full revolutions of the rotor 20 result in three full periods. At maximum permissible excitation current Ie »0, the maximum output voltage Ua1 is generated in the stator winding 18 by means of the now twelve-pole rotor 20 at a predetermined load, with the respective electrical system battery 61 is to supply in the vehicle electrical system in a conventional manner via the bridge rectifier 69. In a likewise known manner, the output voltage Ua of the electric machine 10 is regulated down more or less depending on the DC voltage in the motor vehicle electrical system. For the electric machine 10 according to FIG. 1, this means that, given a correspondingly reduced exciter current Ie> 0, the correspondingly reduced output voltage Ua2 occurs at the stator winding 18, as the overall magnetic field of the rotor 20 is weakened by the weaker electrical excitation in the rotor 20 , This weakening of the total field continues until an exciting current Ie = 0 at which a relatively small output voltage Ua3 is now induced in the stator winding 18. If now even the direction of the excitation current Ie in the exciter coil 29 is changed, results in accordance with Figure 4a and 4b, a reversal of the number of poles 2p on the rotor 20 of twelve poles on four poles. In this case, oppositely directed voltages are induced in the individual coils of a winding strand 70,71, 72,73,74 of the stator winding 18, which cancel each other more or less partially. The resulting output voltage Ua4 now moves in a small range around the voltage value 0. If, finally, the excitation current Ie in the reverse direction to higher values Ie << 0, we obtain a dashed line in Figure 5 shown output voltage Ua5 by 180th ° electrically offset half-waves of the output voltage Ua. For reactive power control, the induced voltage must be adjustable between a maximum and a minimum; it must not become 0 or negative, otherwise the machine tilts into an unstable state.

FIG. 6a shows a rolled-up section of the rotor 20 in plan view, in which the axial extent and the extent in the circumferential direction are seen. Between the Flußleitbereichen 39 of the two Polplatinen 22,23 the annular rotor core 21 is fixed. This results, due to the clamping forces, a deformation of the annular rotor laminated core 21 in the region of the end faces 21 a, 21 b, so that the rotor core 21 lays slightly meander around the flux-guiding regions 39 of the pole plates 22, 23. The deflection of the annular rotor laminated core 21 with respect to the pole plate 22,23 must be greater than 0mm in the proposed system to allow tolerance compensation of the axial dimensions of Polkern 31 and Polplatinen 22,23. However, the deflection s should not be greater than 2 mm, as this stresses the joints of the lamellae of the annular rotor lamination stack 21 and thus the speed resistance of the rotor 20 can no longer be guaranteed. The annular rotor core 21 has an axial length Ie, the flux guide 39 of the Polplatinen each have an axial length of Ip. The length of the rotor laminated core 21 should be in the range of 1.0 to 3.0 twice the length of the flux guide regions 39. The annular rotor core 21 is contacted alternately in the circumferential direction by the flux conducting regions 39 of the pole plates 22, 23, each flux conducting region 39 consisting of two electrically excited pole flux conducting sections 39e, between which a shorter flux conducting section 39m for a permanent magnetically excited pole is located ,

FIG. 6b shows the same segment of the rotor laminated core 21 from FIG. 6a, but in the front view and unwound over the circumference. The annular rotor core 21 has axially extending grooves 32 at a pitch of a pole pitch pt. In these grooves 32, the annular rotor laminated core 21 is welded. Next, the pole-separating permanent magnets 24 are shown, which have a width of bm1, which must be greater than 4mm here, so that the pole-separating permanent magnet 24 is not demagnetized in operation by the opposing field. But it should be less than a third of the pole pitch, so as not to reduce the pole face of the electrically excited poles. The Pole separating

Permanent magnet 24 has a height of hm1, which is between the height he of the annular rotor core 21 and the height of the polbildenden permanent magnet 25 hm2. The pole-forming permanent magnets 25 have a width of b2max which should be between 0.8 and 1.2 times the pole pitch pt. The grooves 32 radially above the pole-separating permanent magnet 24 have a depth of t1. The grooves 32 laterally on the pole forming Permanent magnets 25 have a depth of t2, which should be between 1, 5 and 0.8 times t1.

FIG. 6c shows an alternative of the construction shown in FIG. 6b. Here is a chamfer on each expiring edge of the poles is shown. The running edge here has a width ba and a depth ta. It is advantageous if the width ba is between 0.05 and 0.7 of the pole pitch pt and the depth ta is between 0.01 and 0.1 of the height he of the rotor laminated core 21, wherein a depth of 2 mm should not be exceeded. This chamfering of the poles makes sense for damping magnetic noises for every type of laminated rotor core 21, regardless of whether permanent magnets 24, 25 are used or not.

FIG. 7 shows an example of a method of producing annular stator lamination packages 17 with the grooves 19 and annular rotor lamination packages 21 with the windows 34, 35, wherein the annular stator lamination lamella 17 a is punched free around the annular rotor lamination lamination 21 d. As a result, the waste is reduced to the sheet metal strip 17b used for it. So it is basically advantageous if the annular rotor core has the same sheet thickness of the fins as the kreisringförmi- ge stator core. It is also useful if the sheet material of the rotor laminations is identical.

FIG. 8 shows a side view of an annular rotor laminated core 21. The rotor laminated core is produced from a lamella 40, which is rolled up in a spiral manner. The beginning of the lamella is marked accordingly with 40a and the end with 40b. By producing the annular rotor laminated core 21 from a blade, the waste of the sheet can be further reduced. Beginning 40a and end 40b of the blade 40 are opposite to each other at the axial ends of the annular rotor laminated core, wherein the distance in the circumferential direction should not exceed a pole pitch. It is advantageous if an oxide layer or an insulating layer is located between the lamellae in order to reduce eddy currents on the outer circumference of the rotor 20.

FIG. 9 shows a further embodiment of the invention in a three-dimensional view.

In the annular rotor laminated core 21 are radially on the inner circumference arranged inside extending projections 41. These serve to achieve an accurate positioning of the parts and to increase the radial transfer surface of the magnetic flux from the Polplatinen 22, 23 by the pole plates 22,23, corresponding grooves 42 are provided in which the projections 41 engage. This can improve the magnetic circuit and thus increase the power output of the machine. By the projections 41 and grooves 42 in addition, the annular rotor core 21 is protected against rotation by a mechanical fixation between pole plate 22,23 and rotor laminated core 21 takes place. It is advantageous to arrange the grooves 42 on the pole plates 22,23 and the projections 41 on the annular rotor core 21, since the projections 41 can be punched so easily and the grooves 42 in the manufacture of the mating surface on the pole plate 22,23 by eg do not disturb an overwinding process. In principle, however, it is also possible to arrange the grooves 42 on the annular rotor core 21 and the projections 41 on the pole 22,23. By different offset of the grooves 42 and projections 41 in the circumferential direction or when a corresponding number more grooves 42 are arranged on a pole plate 22 than on the other pole plate 23, can also achieve a mounting aid, which ensures that the pole plates 22,23 only on the for them specific side of the annular Rotorblechpake- tes 21 can be mounted. The Polplatinen 22, 23 are preferably produced by a hot forming process, for example by forging, so that even complicated geometries without or with little mechanical post-processing are possible.

Another measure to fix the annular rotor core 21 is to provide the pole plates 22,23 at the axial transfer surfaces with projections which engage in axial holes or depressions in the annular rotor core.

10 shows the exploded view of a second embodiment of a hybrid-excited rotor 20. In the following, the individual components of the rotor 20 are explained in more detail. Machine shaft 27, excitation coil 29 and pole core 31 are identical to the corresponding parts of the first embodiment shown in FIG. The electronics-side pole plate 23, in a modification to the first embodiment, three Flußleitbereiche 39, which protrude radially from the cylindrical base body of the pole plate 23. Each of the flux guide regions 39 shown here has only one flux guide section 39e. It extends in each case over a Poltei- ment of the twelve-pole rotor 20, wherein all Flußleitbereiche 39 of the Polplatine

Contact 23 in this example electrically energized poles. The field transmission takes place at each flux guide region 39 in the radial direction and in the axial direction into the rotor laminated core 21.

The drive-side pole plate 22 is different in structure from the electronics side pole plate 23. The drive-side pole plate 22 has three Flußleitbereiche 39, each extending over three pole pitches of the twelve-pole rotor 20, wherein the two outer Flußleitabschnitte 39e each have an electrically excited pole of the rotor 20 contact. The respective center pole P of the rotor laminations 21 is contacted at a radially further inwardly located point below the pole-forming permanent magnet 25 of the central flux guide 39m. This avoids that the field of the pole-forming, radially magnetized permanent magnet 25 is short-circuited by the pole plate 22. In principle, it is also possible to produce the drive-side pole plate 22 also from six flux-conducting sections 39e and to omit the material of the flux-conducting sections 39m shown here.

The annular rotor core 21 is preferably laminated in the axial direction. The rotor core 21 has axially extending grooves 32 on the outer surface, which separate the rotor poles P from each other. Furthermore, in the

Rotor laminated core 21 three axially aligned window 35 is provided, in each of which a polbildender, radially magnetized permanent magnet 25 is used. Furthermore, 35 axially aligned windows 34 are provided between the windows, are used in the pole-separating, tangentially magnetized permanent magnets 24. The rotor core 21 is preferably by

Welds held together within the pole separating grooves 32. The rotor laminated core 21 shown here has a total of twelve poles P, wherein three of the poles formed by permanent magnets 23 and ground nine poles electrically grounded. By means of the excitation coil 29, the rotor 20 can thus be switched from twelve outwardly acting poles to six outward poles. To increase the efficiency of the system are at the positions of the rotor laminated core 21, against which the flux-conducting regions 39 of different polarity face each other axially, the pole-separating permanent magnets 24 are inserted. The pole-separating permanent magnets 24 preferably have a rectangular cross-section. The pole-forming permanent magnets 25 preferably have a trapezoidal cross-section. The transfer point of the

Magnet flux from the pole plates 22, 23 to the rotor laminated core 21 is stepped, so that both axial and radial crossing surfaces for the electrically excited field are formed on the shoulders 39a.

FIG. 11a shows the pole sequence occurring on the circumference of the rotor 20, which results in the case of a field current Ie flowing through the field coil 29 in the second exemplary embodiment. Between the pole-separating permanent magnets 24 three pole-forming permanent magnets 25 are arranged on the rotor circumference, which cooperate with the same radial polarity with the field generated by the excitation coil 29. This results in energizing the exciter coil with an excitation current Ie on the rotor circumference twelve poles of alternating polarity. The rotor 20 is constructed such that in the circumferential direction in each case a permanently excited south pole, an electrically excited north pole, a pole-separating permanent magnet 24, an electrically excited south pole, a pole-separating permanent magnet 24, an electrically excited north pole, a permanently excited south pole, an electrically excited north pole , a pole-separating permanent magnet 24, an electrically excited south pole, a pole-separating permanent magnet 24, an electrically excited north pole, a permanently excited south pole, an electrically excited north pole, a pole-separating permanent magnet 24, an electrically excited south pole, a pole-separating permanent magnet 24 and finally one electrically excited north pole follows.

FIG. 11 b shows the state when the current direction in the excitation coil is reversed. In this way, the number of poles of the rotor 20 can be reversed, in which the polarity of the Polplatinen 22,23 and thus the electrically formed poles on the rotor circumference in each case by the reversal of the electrically excited in Fig. 1 a detectable FeI- Φ _{e of} the exciter coil 29 replaced. This results in a six-pole arrangement with alternating symmetrical polarity on the rotor circumference. The fields Φm of the pole-forming permanent magnets 25 indicated in FIG. 11b close over the pole plates 22, 23 or over the pole core 31. The fields Φm shown in FIG. 11a The pole-forming permanent magnets close within the rotor laminated core 21st

FIG. 12 shows the exploded view of a third exemplary embodiment of the hybrid-excited rotor 20. In the following, the individual components of the rotor 20 will be explained in greater detail. Machine shaft 27, excitation coil 29 and pole core 31 are identical to the corresponding parts of the first embodiment shown in FIG.

The electronics-side pole plate 23 shown here has four flux-conducting regions

39, which protrude radially from the cylindrical base body of the pole plate 23. Each of the flux-conducting regions 39 shown here extends, each having a flux-conducting section 39e, over a pole pitch of the twelve-pole rotor 20, with all flux conducting regions 39 contacting electrically excited poles in this example. The transfer point from the pole plate 23 to the rotor laminated core 21 is designed in a stepped manner, so that both an axial and a radial Ü bertrittsfläche for the electrically excited field is formed on the shoulders 39 a. In this case, the transfer surfaces also serve for fixing and centering the rotor laminated core 21.

The drive-side pole plate 22 is identical in construction to the electronics side

Polplatine 23, however, it is rotated by 90 ° mechanically, in order to contact the electrically energized pole P of the rotor laminated core 21 not yet contacted by the electronics-side pole plate 23.

The annular rotor core 21 is preferably laminated in the axial direction. The rotor core 21 has axially extending grooves 32 on the outer surface, which separate the rotor poles from each other. Furthermore, four axially aligned windows 35 are provided in the rotor laminated core 21 in which at least one pole-forming, radially magnetized permanent magnet 25 is used. Furthermore, there are four axially aligned windows 34 are provided in which pole-separating, tangentially magnetized permanent magnets 24 are used. Furthermore, between each one window 35 for a radially magnetized and a window 34 for a tangentially magnetized permanent magnet 24, 25 further axially aligned windows 44 are punched out in the rotor core 21, in which soft magnetic iron cores 43 are inserted.

The axial transfer surfaces of the Polplatinen 22,23 contact directly in the These iron cores 43 improve the conduction of the electrically excited field within the axially laminated lamellae of the rotor lamination stack 21, whereby the power output can be improved. The iron cores 43 are for this purpose preferably by a spring element 45, which is located at one of the axial contacting surface of the pole plate 22,23 opposite end of the rotor core 21 and exerts an axial force on the iron core 43 in the direction of contacting. The spring element 45 can, for example, be designed as a projection in an axial end plate and be biased in accordance with the desired spring effect. This results in at least two different contours of the slats of the rotor core 21. It is also possible to mount the spring elements 45 also within a fan 30 or baffle. Due to the spring elements 45, the iron cores 43 must be equipped by both axial ends of the rotor core 21. The use of iron can be imagined in all described embodiments. The field transmission takes place at each flux guide region 39 in the radial direction and in the axial direction into the rotor laminated core 21, or into the iron core 43.

The rotor laminated core 21 shown here has a total of twelve poles, wherein four of the poles formed by permanent magnets 23 and eight poles are electrically excited. This can be switched by means of the excitation coil 29 of twelve outwardly acting poles on four outward poles. In order to increase the efficiency of the system, the pole-separating permanent magnets 32 are inserted at the positions of the rotor lamination stack 21, on which the flux guide regions 39 of different polarity are located axially opposite each other. The pole-separating permanent magnets 24 preferably have a rectangular cross-section. The pole-forming permanent magnets 25 preferably have a trapezoidal cross-section. The transfer point from the pole plates 22, 23 to the rotor laminated core 21 is stepped, so that both axial and radial transfer surfaces for the electrically excited field are formed on the shoulders 39a.

In Figure 13a, the occurring at the periphery of the rotor 20 Pole sequence is shown, resulting in a current flowing through the exciter coil 29 excitation current Ie. The front pole plate 23 has the registered polarity of a north pole.

Between the pole-separating tangentially magnetized permanent magnets 24 are arranged on the rotor circumference four pole-forming radially magnetized permanent magnets 25 which cooperate with alternating radial polarity with the field generated by the excitation coil 29. This results in energizing the exciter coil with an excitation current Ie on the rotor circumference twelve poles of alternating polarity.

Fig. 13b shows the state when the current direction in the exciting coil is reversed. In this way, the number of poles of the rotor 20 can be reversed, in which the polarity of the Polplatinen 22,23 and thus the electrically formed poles on the rotor circumference changes by reversing the detectable in Figure 13a electrically excited field Φ _{e of} the excitation coil 29, which in Figure 13b by the in brackets illustrated polarity is clarified. This results now in the rotor circumference a four-pole arrangement with alternating symmetrical polarity. The magnetic fields Φm of the poleleting permanent magnets 25 drawn in FIG. 13b close over the pole plates, or over the pole core. The magnetic fields Φm of the pole-forming permanent magnets 25 drawn in FIG. 13a close on the rotor side within the rotor laminated core segment, comprising the respective magnetically excited pole and the two adjacent electrically excited poles.

FIG. 13c shows a schematic representation of the development of the rotor from FIG. 12 with the electrical reversal from 12 to 4 poles. The development extends only over a little more than 3 pole pairs, since the pole sequence then repeats over the remaining rotor circumference. The radial extent of the parts is represented by the arrow R and the circumference by the arrow U. In the upper part of the illustration, the rear pole plate 22, including the rotor laminated core 21 and below the front pole plate 23 is shown. In the case of the higher number of poles, the pole plates and the poles on the circumference of the rotor laminated core 21 have the respectively entered polarities, whereas the polarities recorded in brackets occur due to the electrical reversal to the smaller number of poles. It can be seen that initially the polarity at the adjacent poles of the laminated rotor core 21 always changes over the circumference, resulting in twelve poles according to FIG. 13a. By means of the electric pole control, three adjacent south poles now alternate with three north poles, so that four poles result according to FIG. 13b. FIG. 13c shows a first basic shape of the poles which is repeated over the circumference of the rotor. It begins with a poltennenden permanent magnet 24, followed by an electrically excited north pole and a magnetically excited south pole, which then followed by a mirror image and opposite polarity poltennender permanent magnet 24, an electrically excited south pole, a magnetically excited north pole and an electrically excited south pole. Accordingly, the flux-conducting regions 39 of the pole plates 22, 23 are also formed with a repeating basic shape, after which the electrically excited north poles with the iron cores 43 are contacted by the longer flux-conducting sections 39e of the rear pole plate 22 on the front side. The front sides of the rotor core

21 radially below the magnetically excited south pole are also in case of need, as indicated by dashed lines, contacted by an intermediate shorter flux conducting section 39m. Similarly, the flux guide portions 39e and 39m of the front pole plate 23 are formed. The two Polplatinen 22, 23 are offset with their Flußleitbereichen 39 by 3 poles each against each other.

FIGS. 14 to 20 discuss further alternative solutions of the rotor 20 designed according to the invention in the schematic representation according to FIG. 13c. Here too, the unwinding of the rotor takes place only over part of the circumference with a pole sequence which then repeats itself in its basic form over the remaining rotor circumference. By a corresponding repetition of the basic form in the arrangement of the electrically and permanently magnetically excited poles on the rotor circumference can be machines with larger or smaller PoI- numbers of the rotor 20 represent.

FIG. 14 shows a rotor 20 which can be reversed from 12 to 6 poles according to the embodiment from FIGS. 10 and 11 with the modification of the pole plates 22, 23 in such a way that the shorter flux conducting sections 39m have been omitted here. Consequently, only the flux-conducting sections 39e on the pole plates 22, 23 have stopped here. The basic form in the arrangement of the electrically and permanently magnetically excited poles on the rotor circumference here consists of 4 poles. It starts with a pole-bearing permanent magnet 24, followed by an electrically excited north pole, a magnetically excited south pole and an electrically excited north pole, which is followed by a poltennender permanent magnet 24 and an electrically excited south pole. FIG. 15 shows a rotor 20 which can be reversed from 12 to 6 poles and has a basic shape consisting of four poles. It begins with a pole-bearing permanent magnet 24, followed by an electrically excited north pole and a magnetically excited south pole, which is then followed by a polarizing permanent magnet 24 and an electrically excited south pole in mirror image and opposite polarity. Accordingly, the flux-conducting regions 39 of the pole plates 22, 23 are also formed with a repeating basic shape, whereupon the electrically excited north poles are at the front by a longer Flußleitabschnitten 39e of the rear Polplatine 22 and the rotor core 21 radially below the magnetically excited south pole of an adjacent shorter Flußleitabschnitt 39m are contacted frontally. In the same way, the flux-conducting sections 39e and 39m of the front pole plate 23 are formed and contacted with the rotor lamination packet 21. The two Polplatinen 22, 23 are offset with their Flußleitbereichen 39 by 2 poles each against each other.

FIG. 16 shows a rotor 20 which can be reversed from 12 to 4 poles according to FIG. 13 c, in which only the iron cores 43 inserted in the rotor core 21 are omitted. The rotor has a basic shape consisting of six poles. It begins with a pole-bearing permanent magnet 24, followed by an electrically excited north pole, a magnetically excited south pole and an electrically excited north pole, which is then mirrored and of opposite polarity by a pole-moving permanent magnet 24 , an electrically excited south pole, a magnetically excited north pole and an electrically excited south pole. Compared to the embodiment of Figure 15 have here

Flussleitbereiche 39 of the two Polplatinen 22, 23 in addition to the shortened Flußleitabschnitt 39m of Figure 15 nor a second, longer Flußleitabschnitt 39e for each additional electrically excited pole of the basic shape.

In FIG. 17, a rotor 20 that can be reversed from 16 to 4 poles is one with eight

Poland existing basic form shown. It begins with a pole-bearing permanent magnet 24, followed by an electrically excited south pole, a magnetically excited north pole, an electrically excited south pole and a magnetically excited north pole, which is then mirrored and with opposite polarity a poltennender permanent magnet 24, a magnetically excited

South Pole, an electrically excited North Pole, a magnetically excited South Pole and a electrically excited north pole connects. Accordingly, the flux-conducting regions 39 of the pole plates 22, 23 are also formed with a repeating basic shape. In contrast to the embodiment according to FIG. 16, the flux-conducting regions 39 of the two pole-plates 22, 23 have, in addition to the second longer flux-conducting section 39e, additionally a shortened flux-conducting section 39m for the respective additional magnetically excited pole of the basic shape.

FIG. 18 shows a rotor 20 which can be reversed from 12 to 2 poles and has a basic shape consisting of twelve poles. It starts with a poltennenden permanent magnet 24, followed by an electrically excited north pole, a magnetically excited south pole, an electrically excited north pole, a magnetically excited south pole, an electrically excited north pole and a magnetically excited south pole, at which then a mirror image and with opposite polarity Poltennender permanent magnet 24, a magnetically excited north pole, an electrically excited south pole, etc. connects. Accordingly, the flux guide regions 39 of the pole plates 22, 23 are also formed with a basic shape. Compared with the embodiment according to FIG. 17, the flux-conducting regions 39 of the two pole-plates 22, 23 have, in addition to the second, shorter flux-conducting section 39m, a further longer and shorter flux-conducting section 39e and 39m for the respective additional magnetically and electrically excited pole

Basic form.

FIG. 19 shows a rotor 20 that can be reversed from 14 to 2 poles, in which, in comparison to the embodiment according to FIG. 17, instead of three now four electrically excited north poles alternate with three permanent magnetically excited south poles.

Furthermore, the pole-separating permanent magnets 24 are thus arranged between two adjacent electrically excited poles of different polarity and not, as in FIG. 17, between two adjacent permanent-magnetic poles. Accordingly, in the region between two pole-separating permanent magnets 24 on the flux-conducting region 39 of the pole plate 22, three flux-conducting sections 39m are arranged between four longer flux-conducting sections 39e. The Flußleitbereich 39 of the front pole plate 23 is formed in the same way, but added to a corresponding pole sequence with opposite polarity. FIG. 20 shows a rotor 20 which can be reversed from 16 to 2 poles and has a basic form consisting of 16 poles, in which, instead of three, four magnetically excited south poles alternate with four electrically excited north poles in comparison with the embodiment of FIG. Furthermore, the pole-separating permanent magnets 24 are thus arranged between two adjacent magnetically excited poles of different polarity and not, as in FIG. 17, between two adjacent electrically excited poles. Correspondingly, in the area between two pole-separating permanent magnets 24 at the flux-conducting region 39 of the pole plate 22, four shorter flux-conducting sections 39 m are arranged next to four longer flux-conducting sections 39 e. The flux guide region 39 of the front pole plate

23 is a mirror image formed in the same way, but added to a corresponding pole sequence.

The invention is not limited to the illustrated embodiments. For example, the shorter flux conducting sections 39m according to FIGS. 14 and 16 may be dispensed with in the pole plates. Furthermore, in all exemplary embodiments, the pole plates 22, 23 can also be provided on the flux-conducting regions 39 with a shoulder 39a, which then bears against the inside of the rotor laminated core 21 in each case. It can also be seen from FIGS. 15 to 17 and 18 to 20 that the distances from one pole-separating permanent magnet 24 to the next in each case increase by one pole over the circumference of the rotor laminated core 20, and the flux-conducting regions 39 of the two pole-plates 22, 23 accordingly increase a pole width. Consequently, the pole-separating permanent magnets 24 are arranged either between two electrically or between two magnetically excited poles. This system is generally, that means also for the arrangement, not shown, of five poles between two pole-separating permanent magnet 24. Furthermore, in principle, the excitation coil 29 can be divided into several coils if necessary.

Claims

claims 1 . Hybrid excited electrical machine (10) having a fixed stator (16) supporting a preferably polyphase stator winding (18) and having a rotor (20) cooperating with the stator via a working air gap and a plurality of a predetermined number over its circumference by means of permanent magnets (25) excited and by at least one excitation coil (29) electrically excited pole (P), wherein the number of poles (2p) of the rotor depending on the strength and direction of an excitation current (Ie) in the at least one excitation coil is reversible, characterized in that the at least one exciter coil (29) is designed as an annular coil arranged around the machine axis (x). 2. Electrical machine according to claim 1, characterized in that the at least one exciter coil (29) on a cylindrical pole core (31) is placed on the end faces in each case a pole plate (22, 23) is arranged. 3. Electrical machine according to claim 2, characterized in that the pole core (31) with the pole plates (22, 23) on a machine shaft (27) is fastened. 4. Electrical machine according to claim 2 or 3, characterized in that the at least one exciter coil (29) by an annular rotor core (21) is concentrically surrounded, in which the preferably radially magnetized permanent magnets (25) are used. 5. Electrical machine according to claim 4, characterized in that the two Polplatinen (22, 23) with radially outwardly directed Flußleitab- sections (39e, 39m) on the end faces (21 a, 21 b) of the rotor laminated core (21) abut. 6. Electrical machine according to claim 5, characterized in that the Flußleitabschnitte (39e, 39m) of a Polplatine (22) to the Flußleitab- sections (39e, 39m) of the other Polplatine (23) in each case by at least one pole pitch (pt) of higher number of poles are offset. 7. Electrical machine, preferably three-phase generator for motor vehicles, according to one of the preceding claims, characterized in that the rotor (20) with a five-phase stator winding (18) cooperates, the five winding strands (70-74) to a five-pointed star are connected in series, preferably by each one adjacent winding strand (71, 73, 70, 72, 74) is skipped. 8. Electrical machine, preferably three-phase alternator for motor vehicles, according to one of the preceding claims, characterized in that see between the electrically and the magnetically excited poles (P) on the circumference of the rotor (20) tangentially magnetized, pole-separating permanent magnets (24) in the rotor core (21) are used. 9. Electrical machine according to claim 8, characterized in that the tangentially magnetized, pole-separating permanent magnets (24) in each case between two permanent magnetically excited poles (P) or between a permanent magnet and an electrically excited pole (P) or between two electrically excited poles (P ) are arranged. 10. Electrical machine according to one of the preceding claims, characterized in that the output voltage (Ua) of the stator winding (18) by a change of strength and direction of the excitation current (Ie) of the at least one excitation coil (29) preferably load and temperature dependent between a permissible maximum value and the value zero is controllable. 1 1. Electric machine according to one of the preceding claims, characterized in that in normal generator operation of the machine (10), the rotor (20) has the higher number of poles (2p) and wherein the strength and direction of the excitation current (Ie) are chosen so that in cooperation with the Permanent magnets (24, 25) on the circumference of the rotor (20) approximately equally strong poles (P) of alternating polarity occur. 12. Electrical machine according to one of the preceding claims, character- ized in that at least one of the pole plates (22, 23) has a Flußleit- area (39) with several Flußleitabschnitten (39e, 39m), which at least one electrically excited pole (P ) and preferably also a permanent-magnetically excited pole (P). 13. Electrical machine according to one of the preceding claims, characterized in that at least one iron core (43) in the region of the electrically excited poles (P) in the rotor laminated core (21) is inserted. 14. Electrical machine according to one of the preceding claims, character- ized in that the rotor laminated core (21) at the periphery in each case between two poles (P) has a pole-separating groove (32). 15. Electrical machine according to one of the preceding claims, characterized in that punched out in the rotor laminated core (21) below each permanent magnetically excited pole (P) an approximately the Polbreite correspondingly wide window (35) for receiving a radially magnetized permanent magnet (25) is. 16. Electrical machine according to claim 14, characterized in that in the rotor laminated core (21) for receiving a tangentially magnetized, pole-separating permanent magnet (24) a rectangular, radially aligned window (34) is punched below a pole-separating groove (32). 17. Electrical machine according to claim 16, characterized in that at the higher pole number (2p) of preferably twelve poles (P) between two permanent magnetically excited poles (P) with alternating polarity two electrically excited poles (P) with alternating polarity on the circumference of the rotor laminated core (21) are arranged. 18. Electrical machine according to claim 17, characterized in that at the higher pole number (2p) of preferably twelve poles (P) between each two permanently magnetically excited poles (P) with the same polarity are arranged three electrically excited poles (P) of alternating polarity. 19. Electrical machine according to claim 12, characterized in that the Flußleitbereich (39) on the outer circumference of the Polplatinen (22, 23) in each case by a shoulder (39a) is discontinued from the boards, which rests against the inner circumference of the rotor laminated core (21). 20. Electrical machine according to claim 19, characterized in that the Flußleitbereiche (39) of the Polplatinen (22, 23) in the circumferential direction by a respective recess (22a, 23a) are separated from each other, the bottom (22b, 23b) radially below the shoulder (39a) lies. 21. Electric machine according to claim 12 and 15, characterized in that the flux-conducting region (39) of the pole plates (22, 23) with one (39m) of its Flußleitabschnitte (39e, 39m) radially below a permanent magnet (25) with the end face (21a, 21 b) of the rotor laminated core (21) is contacted. 22. Electrical machine according to one of claims 1 to 4, characterized in that the rotor laminated core (21) at the poles (P) at least one chamfer (21 c) whose width (ba) the 0.05 to 0.7 times the pole pitch (pt) of the higher number of poles and whose depth (ta) corresponds to 0.01 to 0.1 times the radial height (he) of the annular rotor laminated core (21).