WO2007093487A2

WO2007093487A2 - Permanently excited synchronous machine and method and apparatus for operating said machine

Info

Publication number: WO2007093487A2
Application number: PCT/EP2007/050715
Authority: WO
Inventors: Marco Falco; Ralf Kruse
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-02-14
Filing date: 2007-01-25
Publication date: 2007-08-23
Also published as: DE102006006824A1; WO2007093487A3

Abstract

In a permanently excited synchronous machine (1) with a stator (2) which surrounds a rotor (4), which has permanent-magnet rotor material, so as to form an air gap (3), a number of permanent magnets (6) which can be magnetized and demagnetized by means of a field-forming longitudinal current (id) are arranged in a recessed fashion in the rotor (4) or in the rotor material (4'). During operation of the synchronous machine (1), the longitudinal current (id) is impressed on the stator winding in at least two stages in order to set the magnetization state of the rotor-end permanent magnets (6), with the permanent magnets (6) being at least approximately fully magnetized in a first stage, and with the permanent magnets (6) being demagnetized or unmagnetized in a second stage.

Description

description

Permanent-magnet synchronous machine and method and device for its operation

The invention relates to a permanent-magnet Syn ^¬ chronmaschine with a stator winding to produce a rotating field having stator which surrounds a rotor, a permanent magnetic material having rotor forming an air gap. It further relates to a method and an apparatus for operating a variably permanent-magnet synchronous machine, in particular in a hybrid vehicle.

In such a synchronous machine with a stator-side, usually three-stranded and operated with a three-phase sinusoidal AC stator or rotating field winding occurs in the air gap between the stator and the permanent-magnet rotor a rotating magnetic field or stator rotating field. This stand-side rotating field be ^¬ is of alternating magnetic north and south poles, which rotate along the air gap. The total number of all north and south poles indicates the so-called pole number (2p) or pole pair number (p). Due to the interaction between the stator rotating field and a rotor rotating field or exciting field generated by the permanent-magnet rotor, the torque of the synchronous machine is created.

The permanent-magnet synchronous machine is operated at variable speed, for example in conjunction with a frequency converter and a pulse width modulation. In stationary operation, the synchronous machine rotates with synchro ^¬ ner speed by the rotor rotating at a speed of rotating field of the stator corresponding speed. These

Speed is determined by the frequency of the applied stator voltages and thus the stator currents, the Speed and the stator frequency are linked directly proportional to each other via the number of pole pairs.

As a result of the interaction between the stator and the rotor rotating field induces a voltage in the winding phases of the stator winding, which is proportional to the stator voltage Fre ^acid sequence and is capable of flux linkage in the air gap. This in turn results from a superposition of the stator flux linkage and the rotor flux linkage. At high speeds and thus high stator frequencies, this resulting flux linkage must be correspondingly small so that the maximum permissible induced voltage is not exceeded. At high speeds, the synchronous machine is therefore in the so-called field weakening range.

In a permanent-magnet synchronous machine with rare-earth or ferrite magnets as the rotor-side magnetic material, the rotor flux linkage is virtually constant regardless of operating point, since the permanent magnets or permanent magnets produce an approximately always high field. In order to achieve the desired field weakening at high speeds, a corresponding opposing field must be specified on the stand side. This as ^¬ derum can be achieved by compensating or weakening of the exciter field by the stator windings is impressed A corresponding field-weakening current.

From DE 33 34 149 Al it is known, in a Synchronma ^¬ machine with permanently energized by AlNiCo magnets rotor of the stator winding via a converter for a short time a current - the so-called (negative) longitudinal flow - supply. The resulting in the longitudinal direction - and thus along the machine longitudinal axis - caused flooding an irreversible change in the magnetization state of the rotor-side permanent magnets. By impressing short-term current pulses, the permanent magnets of the rotor can be magnetized or magnetized. A demagnetizing longitudinal current leads to a relatively weak field of excitation of the synchronous machine, so that these also operate at high speeds. can be operated with low losses and safe. At lower speeds, a longitudinal aufmagneti- sierender current is generated accordingly, of the exciter field entspre ^¬ is accordingly strengthened so as to produce, at low speeds a large torque as possible.

Although in the known arrangement already consisting of a material of relatively small Koerzitivfeidstärke part magnets, in particular AlNiCo magnets, provided. Nevertheless, it has been found that with this known arrangement, at least in the field weakening range, undesired interference effects, such as, in particular, incalculable oscillating torques or noise ^¬ stimulations can occur.

The invention has for its object to provide a permanent ^¬ excited synchronous machine whose permanent magnetic field is variable while avoiding the disadvantages mentioned. Furthermore, a method and an apparatus for operating, in particular for the control or regulation, of a variably permanent-magnet synchronous machine are to be specified.

With respect to the permanent magnet synchronous machine, this object is achieved by the features of at ^¬ entitlement 1. For this purpose, the permanent magnets are buried in the rotor or fermaterial lauter arranged.

With respect to the method and apparatus for operating such, synchronous machine, hereinafter also referred to as variable permanenterreg ^¬ ter motor or VP-motor is the aforementioned object according to the invention achieved by the Merkma ^¬ le of claims 22 and 25 respectively.

Advantageous variants, embodiments and / or developments are the subject of the respective subclaims.

The invention is based on the one hand based on the consideration that the instantaneous water-side permanent magnetic field particularly reli ^¬ can be varied transparent when an undesirable affect Fluxing of the magnetization state of the rotor side Mag ^¬ netmaterials is avoided by the stator or rotor rotating field or at least as low as possible.

In this regard, the invention is based on the recognition that, on the one hand, based on a rotor-fixed coordinate system, the so-called dq coordinate system, only the longitudinal current oriented in the direction of magnetization of the rotor, ie in the direction of the longitudinal axis or the d-axis, as field strengthening or field weakening or. generally as field-forming - current is effective. However, any of the torque-forming current in the direction of the perpendicular to this cross-axis or q-axis oriented transverse ^¬ stream. Both the leading to the field weakening negative longitudinal current and the leading to a field enhancement positive longitudinal current influences as ^¬ at the air gap induction, but not the torque , Conversely, the cross flow affects the torque, but not the excitation field.

On the other hand, the stator winding is always generates a spatially sinusoidal magnetic field in the air gap, with the result that a light generated by cross-flow air gap field the Mag ^¬ netzustand of the rotor and used particularly in areas affected for remagnetization provided permanent magnets. This undesirable effect is also adversely affected the extent or enhanced magnetic materials used as the giearmen the possible benefit or ener ^¬ magnetic reversal, as particularly AlNiCo or FeCrCo, in addition to a ver high remanence ^¬ same manner also have a relatively small coercive field strength. Therefore, already at a relatively low cross-flow induced field strength or change in field strength as well as an unwanted and undesired particular not or only insufficiently controllable Be ^¬ takes place influencing or changing the state of magnetization of the magnets on the rotor side used.

Affected by this undesirable influence by the cross flow are recognized to be essentially the outer, the air gap facing and thus the stator next to him ge ^¬ nen regions of the rotor-side permanent magnets or poles. Therefore would be up to the air gap extending permanent magnets ^¬ lead to an unwanted cross-flow related field weakening.

Furthermore, studies show that on the one hand fig comparatively narrow at a spoke geometry with trapezoidal permanent magnets inevitably ^¬ inner magnetic regions are more easily demagnetized than the then comparatively wide in this geometry outer magnetic regions of the lauter ferseitigen permanent magnets. In this case, relatively small longitudinal currents are already sufficient for influencing the radially inner magnetic regions. On the other hand, only the radially outer magnetic regions can be fully magnetized at maximum rotor field, while the inner Magnetbe ^¬ rich then only partially magnetized. This would lead to a correspondingly reduced torque of the synchronous machine due to the resulting ineffective use of the magnetic material. Since it is the relatively well up magnetizable outer magnetic areas are sensitive heavily exposed to the air gap generated by a cross-flow stator or armature transverse field due to the vicinity thereof, is a unge ^¬ wanted crossflow conditional field weakening or demagnetization of the permanent magnets practically unavoidable.

This unwanted effect of an unwanted demagnetization of the permanent magnets by the armature transverse field can be avoided by a geo ^¬ metric design or arrangement of the permanent magnets, in which although the known slight demagnetization used, but at the same time the influence of the armature transverse field is kept as low as possible. Here ^¬ be particularly suitable is a ner at certain or pre give ^¬ radial thickness of the rotor material in radial direction possible liehst deep in the rotor or rotor of the synchronous machine ver ^¬ lowered arrangement of the permanent magnets. Under sunk arrangement of the permanent magnet in the rotor or in the rotor material is understood here that - in the radial direction of the rotor consider- tet - on the one hand, the radial extent or dimension of the permanent magnets is smaller than the radial material thickness or dimension of the rotor, which is otherwise soft or ferromagnetic, for example, with Blechchpaket- or dynamo sheet-like yokes. On the other hand, the permanent magnets are located with the air gap in the spaced-apart top or surface in the rotor material.

If the permanent magnets sunk in the rotor material are square or preferably rectangular in shape, a particularly uniform magnetization and demagnetization of the entire rotor-side magnet volume or material is made possible. It is also recognized that a particularly uniform magnetization of all radial magnetic layers of the permanent magnets is observed. The rectangular permanent magnets are preferably recessed with the rotor axis and the air ^¬ gap-facing longitudinal sides in the rotor material.

For this purpose, in the rotor or in the rotor material corresponding recesses for receiving the respective permanent magnets see pre ^¬, that is incorporated in particular in the Läuferjoche. Since the radial extent of these recesses open towards the air gap is greater than the radial thickness of the permanent magnets and these are guided against the bottom or bottom of the respective recesses, a permanent magnet-free space remains between the magnet surface or upper side and the air gap. The recesses are expediently carried out in stages to form two circumferentially differently wide spaces.

When in the radially inner, comparatively wide space of the recess inserted permanent magnet can be used in the radially outer, relatively narrow space of this recess a cap or plug-like cover made of non-magnetic material. As a result, the recesses are closed by means of appropriate magnetic covers. The advantageous in particular from constructive and ho ^¬ hen speeds from noise engineering reasons Magnetic covers have practically no influence on the electromagnetic behavior of the synchronous machine.

The provided along the circumference of the rotor permanent magnets WEI sen in terms of material expediently A possible ^¬ lichst low coercive field strength on at the same time as high as possible remanence. Due to this combination of geometry and material, the permanent magnets magnetized in the circumferential direction always enable the rotor field to exit the rotor block in the same way. Preferred magnetic materials are AlNiCo or FeCrCo.

In an expedient development so-called river barriers are provided in the runners. The flow barriers serve to reduce a transverse inductance in order to be able to impress the transverse currents necessary for a sufficiently high torque over the entire speed range into the stator winding. The number of flow barriers expediently distributed uniformly around the circumference of the rotor corresponds to the number of permanent magnets, with each respective permanent magnet being provided with a flow barrier on both sides. The shape of the flow ^barriers can be rectangular. In view of an increase in the air gap field, however, triangular flow barriers are advantageous. Here, the flux barriers with their triangular tip are directed towards the air gap and used in these zweckmäßi ^¬ gerweise directly adjacent in the rotor or in the rotor ^¬ material or in the Läuferjoche.

According to a preferred variant of the variable-permanent-magnet synchronous machine whose stator winding is designed as a so-called Bruchlochwicklung. Such a broken hole winding has, in contrast to a Ganzlochwicklung with a full number of holes a broken number of holes. The number of holes is the number of stator slots per pole and phase winding. A two-pole synchronous machine with three-phase stator winding can, for. B. have twelve (12) stator slots and therefore per pole two (2) stator slots per winding strand. The number of holes in this case would have the value two (2), which corresponds to a Ganzlochwicklung. In the case of a broken hole winding, on the other hand, the number of holes has a fractional value of, for example, two and a half (2.5) when the stator has a total of fifteen stator slots and therefore seven and a half (7.5) stator slots per pole.

The use or the use of a fractional-slot winding leads so-called cogging torques to a significant reduction, in part by way especially in a variable permanent-magnet motor with its use in a hybrid vehicle, especially before ^¬. Such (dead) latching or Nutrastmomente can lead to undesirably high torque fluctuations and corresponding speed fluctuations when the runner practically aligns in operation on the stator teeth.

The reason is that, particularly when a magnet with spokes ^¬ executed permanent magnet rotor, the magnetic permeability along the rotor or air gap periphery strong fluctuations shows by ferromagnetic Eisenberei- che very high permeability to magnetic and / or Flusssper ^¬ very renbereichen low permeability change. This occurring in a Ganzlochwicklung effect is significantly reduced at a Bruchlochwicklung.

The variable permanent-magnet synchronous machine is operated ^¬ preference by means of the so-called field-oriented control. This type of control is oriented on the rotor field and thus with respect to the rotor-fixed dq-coordinates on the d-axis. Field-oriented control controls the already magnetized synchronous machine initially solely on the basis of a torque-forming current component, ie by means of the cross ^¬ stream according to its magnitude and sign. For this purpose, the winding phases of the stator winding are specified in accordance with a desired operating parameter, in particular a desired torque value, manipulated variables for the phase voltages for generating the corresponding rotary field. Is due to the current speed of the rotor and of the synchronous machine changing the state of magnetization of the permanent magnets or the degree of magnetization of the Läu ^¬ fers or the rotor material necessary, for example with respect to a field weakening, the stator winding is in addition to the torque-forming cross-flow a field forming pulse-shaped longitudinal current imprinted in two stages to magnetize the permanent magnets.

In this case, in a first stage, the longitudinal flow is initially adjusted such that the permanent magnets are at least approximately completely magnetized. Only in a second stage is then the targeted Ab- or magnetic reversal of the permanent magnets. Under re-magnetization here is only the up or demagnetize, but not understood a polarity reversal of the permanent magnets.

In view of the possible be simulated for an optimized operation of the synchronous machine field weakening the generating of the permanent magnet to the magnetic field depends in the simplest case only by the speed of the rotor from, and with too ^¬ participating speed decreases the required level of magnetization. By means of the field-oriented control is thus ^¬ attracted to a rotor-fixed dq coordinate system in addition to the torque-forming cross-current required for a field weakening as required longitudinal flow depending on the current speed of the rotor for adjusting the corresponding magnetization levels of the permanent magnets gesteu ^¬ ert In the first stage, fully magnetized permanent magnets are demagnetized correspondingly both with rising or increasing speed and with decreasing or decreasing speed.

Thus, the magnetization state of the permanent magnets of the rotor can be targeted, ie ver ^¬ comparatively precise and in particular reproducible ^¬ sets by the two- or multi-stage imprint of short-term current pulses in the stator winding. The permanent magnets can be used as needed a field weakening or field enhancement by targeted adjustment of the direction and height of the magnetic field generated by the negative or positive longitudinal flow in the second or further stage or be magnetized.

With respect to this aspect of the at least two-stage Ummag- netisierungskonzeptes for operating the variable permanent ^¬ excited synchronous machine, the invention is based on the realization that the space required for a given level of magnetization of a variably magnetizable permanent or permanent magnet magnetizing current is dependent on the previous state of magnetization of this magnet. Along the typical hysteresis curve in the magnetization field strength diagram (BH) plot of such a magnet, for example, AlNiCo or FeCrCo material, this is reflected as a reminder effect designated previous magnetization or output ^¬ state in the respective remanence again. Since, within the magnet-specific hysteresis, the remanence in turn determines the coercive field strength required for demagnetization and thus magnetization reversal of the magnet and this in turn is different at different remanences, the required field strength of an external magnetic field depends on the initial state of the magnet. Consequently, on the one hand, different longitudinal currents would be required for mutually different initial magnetization or initial states of the magnet in order to achieve the same final magnetization level to be set. On the other hand, a certain longitudinal current would result in different reactions of the magnet with different initial magnetization or initial states from each other.

In the particular application of such variably magnetizable Barer permanent magnets for generating a required, Variegated ^¬ cash rotor field of a synchronous machine this occurs Erin- nerungs effect also with in different radial positions of the permanent magnets different remanences or output states on. With regard to this aspect of the invention is to supply Überle ^¬ basis that a certain longitudinal flow would lead to a defined reaction of the magnet when the reminder effect can be neutralized. This, in turn, can be achieved if initially a defined starting state of the magnet can be established independently of the original magnetization state. In such a defined initial state, the magnet is known to be completely magnetized, ie along the hysteresis is at least approximately in the range of maximum Magne ^¬ tion. Based on this saturated magnetization state, the magnet always behaves the same with respect to the remanence and the Keorzitivfeidstärke at the same longitudinal flow due to a Ab- or Ummagnetisierungsvorgangs.

Therefore, it is prepared first the defined initial state by an entspre ^¬ sponding longitudinal current pulse in a first stage or in a first step. As is known, all radial magnetic layers are then equally in a state of complete magnetization, regardless of their respective distance from the air gap or the stator of the synchronous machine, in particular in the case of a rectangular permanent magnet. Subsequently, in a subsequent second stage or in several successive stages, the magnetization state of the rotor-side variably magnetizable permanent magnets required for a particularly effective mode of operation of the synchronous machine can be set precisely.

The advantages achieved with the invention consist insbesonde- re fact that by the recessed geometrical arrangement of the permanent magnets in the rotor or rotor material is an Although in amplitude desirably manner proportional to the magnetization level or state change ^¬ of, but not undesirably its curve shape changing rotor field is adjustable. In particular, a controlled controllable field weakening at all speeds is possible. In this case, an undesired Drehmo ^¬ element influencing the other hand, on the one hand a non or only insufficient long-term controllable or unintended Ummagnetisie- tion of the rotor-side permanent magnets avoided.

Due to the geometric design of the rotor with recessed arrangement of the expediently rectangular permanent magnets overall a particularly high utilization of the synchronous machine in all operating ranges, i. achieved a particularly high on the size of the torque. By this special geometric arrangement of the magnetic circuit with rotor-side sunken permanent magnets can also be achieved maximum torque while minimizing the use of magnetic material.

Also, the synchronous machine has a particularly high efficiency in all operating or load ranges. We are ^¬ sentliche reasons for this is that virtually no zusätzli ^¬ chen loss flows through Feldschwächströme or negative longitudinal ^¬ and no rotor losses occur.

In particular, in hybrid applications, the DC or DC power consumption at the start of the internal combustion engine of a corresponding hybrid vehicle is particularly low. The Syn ^¬ chronmaschine is therefore particularly advantageous also in a 14V electrical system and thereby both as a variable permanent-magnet motor and as a variable permanent-magnet generator can be used.

The synchronous machine according to the invention is furthermore distinguished by a high degree of robustness, especially since the AlNiCo which is preferably used for the rotor-side permanent magnets.

Magnetic material is resistant to corrosion and to a tempera ture of about 500 ^¬ ⁰ C temperature resistant. Also, neither overvoltages in the event of a fault nor unwanted irreversible demagnetizations of the permanent magnets are to be expected. Since the lauter can be fer moreover completely demagnetized in case of need, a particularly high degree of assembly and was ^¬ is given tung friendliness. Since the reminder effect by way of a reset function tion neutralizing output state of complete magnetization ^¬, in particular for all the magnetic layers of the läuferseiti- gen permanent magnets, both regardless of the shape of the permanent magnets is provided as well as whether and if so how deep, the permanent magnets are sunk into the rotor, this two-stage control concept is in principle also advantageously used in such va ^¬ riabel permanently excited synchronous machines with running up to the air gap Speichenmag- neten or with attached to the rotor variable magnetizable permanent magnet or surface magnet are. The method and the device according to claims 22 and 25 accordingly also constitutes an independent invention.

Embodiments of the invention will be explained in more detail with reference to a drawing. Show:

1 shows schematically in a cross section a two-pole (p = 1) variable permanent magnet synchronous machine with three-phase stator winding and with sunken in the rotor rectangular permanent magnet,

2 shows a synchronous machine according to FIG. 1 with triangular flow barriers in the rotor,

3 is a synchronous machine according to FIG 2 with Bruchloch ^¬ winding and rectangular flow barriers,

4 shows a block diagram of the overall structure of an electric drive with a variably permanent- ^magnet synchronous motor (VP motor) in a hybrid vehicle,

FIG. 5 is a block diagram of a variable permanenterreg ^¬ th synchronous machine as a motor with a VP-Re ^¬ gel means, 6 shows in a current-time diagram the current and time ratios of short-time magnetization or demagnetization pulses,

7 shows in a magnetization-speed diagram the dependence of the magnetization state of rotor-side permanent magnets on the working or engine speed of the VP motor,

8 shows in a BH diagram outer and inner hysteresis ^¬ courses of a magnetized AlNiCo material, and

9 shows in a representation according to FIG. 8 the hysteresis curves of two partially magnetized magnetic layers of the magnetic material.

Corresponding parts are provided in all figures with the same reference numerals.

The 1 and 2 schematically in cross-section ^{dargestell ¬} te permanent-magnet synchronous machine 1 has a stator 2 in the exemplary embodiment twelve stator slots (+ U, + V, + W), in which a three-phase rotating field winding with corre sponding ^¬ assignment of the stator slots to the three winding strands U, V and W of the rotating field or stator winding is inserted.

In steady-state sinusoidal steady state operation, in the timing considered in FIGS. 1 to 3, the winding strands U currently lead to the maximum positive current, while the other two winding strands V and W are each leading to half the negative current. This is illustrated in the left-hand illustration section of FIG. 1 on the basis of the topographical representation of the three winding phases U, V, W connected in star there. Here, a positive current means a cross in the plus-signed ladder stator slots + U, + V, + W. Furthermore, according to convention, a cross means that it flows into the picture or drawing plane. the current, while a point illustrates a flowing out of the image or Zei ^¬ chenebene stream. By relatively high-strength crosses and points Ver ^¬ comparatively high amount of current is marked, while comparatively thin crosses and points a correspondingly low

Mark the amount of electricity. Overall, thus shows for the sought time ^¬ be in the stator 2, an approximately sinusoidal current distribution ^¬ shaped along the circumference of the synchronous ^machine. 1

When supplied with a three-phase sinusoidal alternating current, the stator winding U, V, W generates a circulating in the air gap 3 between the stator 2 and a rotor 4 magnetic field or stator rotating field. This stator rotating field consists of alternating magnetic north poles N and south poles S, which rotate along the air gap 3. The pole number 2p ^¬ which may be practically any case of the inventive synchronous machine 1 is, with regard to exemplary embodiments of clarity in the examples shown in Figures 1 to 3 Training 2p = 2. The number of pole pairs is p = accordingly. 1

The rotary field generated by the stator 2 surrounds the current-carrying conductors of the stator windings U, V, W on the right, so that at the time considered on the machine top of the synchronous machine 1, a stator south pole S and on the machine base a stator north pole N is obtained , The two stator poles S and N, the concentrated non-selectively on the machine upper side and on the machine base ^¬ are trated, encompass sinusoidal corresponding to the zugehö- ring stator current lining ± U, ± V, ± W in each case one pole pitch, which in the present poles 2p = 2 corresponds to half the circumference of the synchronous machine 1. In the present case, therefore, the stator south pole S is distributed as a half-sine wave over the machine ^upper side, while the stator north pole N is distributed as a sinusoidal half-wave over the machine underside.

The rotor 4 is equipped with permanent or permanent magnet 6. In the embodiments of FIGS 1 to 3 in each case two Dau ^¬ ermagnete 6 arranged opposite each other on the rotor side are sunk in the runner material otherwise existing, for example, as a laminated core 4 ^λ , and thus sunk into the rotor 4. For this purpose, corresponding recesses 7 are provided in the rotor 4 or rotor material, into which the permanent magnets 6 are inserted. Each having a north pole and a south pole having Dauermag ^¬ numeral 6 are in the embodiment of rectangular shape with a ^¬ hand to the air gap 3 and on the other hand to the rotor axis 8 oriented toward the longitudinal sides.

The permanent magnets 6 are used to form a radial distance c to the air gap 3 in the permanent magnet rotor material 4 ^λ . The radial thickness or extent d of the permanent magnet 6 is smaller than the depth or groove depth a of the respective recess 7. In the present embodiment, the radial depth a of the recesses 7 is about twice as large as the radial thickness d of the respective permanent magnet. 6 The recesses or grooves 7 are formed in stages to form two receiving spaces, wherein the Dauermag ^¬ designated 6 in the air gap 3 facing away, radially inward receiving space of the respective receiving groove 7 einliegen.

The remaining in the recesses 7 permanent magnet 6 remaining receiving space 9 in the recesses 7 between the respective permanent magnet 6 and the air gap 3 is filled by a magnetic cover 10 made of non-magnetic or non-magnetic material. By the respective magnet-free receiving space 9 is completely filled by means of the corresponding magnetic cover 10, the recesses 7, in which the permanent magnets 6 are inserted sunk, completely closed. In addition, since the receiving space 9 in the circumferential direction of the rotor 4 is narrower than the inner receiving space of the recess 7, the permanent magnet 6 sunk into it is held positively and securely.

For the execution of the synchronous machine 1 as a variably per ^¬ manenterregter motor (VP motor) are to achieve a ho torque M and, at the same time, good remagnetization of the permanent magnets 6 as magnetic material AlNiCo materials and FeCrCo alloys are particularly advantageous. These magnetic ^¬ materials typically have a high remanence Iinduktion at the same magnitude very low pERSonal zitivfeidstärke.

The permanent magnets 6 generate a rotor side rotating field with the same number of poles 2p = 2 and the same pole pair number p = 1 as the stator rotating field. The stator rotating field and the rotor rotating ^¬ field occur during operation of the synchronous machine 1 in mutual interaction, so that a torque is generated. By means of Lorentz's law of force, torque generation can be explained with respect to stator 2 such that the magnetic rotor field generates Lorentz forces due to its effect on the current-carrying conductors of winding phases U, V, W of the stator winding, which in total sum the torque on stator 2 cause. See as a result of the alternating ^¬ operation principle according to the Newton's law, "action est reac- tion" a torque acts the same height in the reverse Rich ^¬ processing on the rotor. 4

For the time shown in FIGS. 1 to 3, both permanent magnets 6 have their north pole on the right side of the figure and their south pole on the left side of the figure. The runner 4 provided with the permanent magnets 6 thus generates at the time in the representations according to FIGS. 1 to 3, on the right, a north pole N and on the left a south pole S. The field of the rotor north pole N acts on the right side of the synchronous machine 1 in FIG with + U designated ^¬ Neten head of the corresponding phase winding U a. The force effect is accordingly a downwardly directed force on the stator winding in the direction of the arrow 5. Overall, this causes a torque on the stator 2 in a mathematically negative sense. As a result of the interaction principle "actio est reactio" this is synonymous with a torque in the mathematically positive sense and thus in the direction of the arrows 11 in the counterclockwise direction of the rotor 4. In also mathematically positive direction of rotation, the synchronous machine 1 is in motor operation.

The following explanations also refer to the rotor-fixed dq coordinate system, which is indicated on the rotor axis 8 in FIGS. 1 to 3, and which rotates with the rotor 4. The drawn d-axis or the longitudinal axis is always in the direction of the rotor field, ie in the direction of the rotor ^¬ North pole N. The q-axis or the transverse axis is perpendicular to the d axis. At the time considered to be magnetized during operation of the synchronous machine 1 three Stän ^¬ derstrangströme the stator 2 in the direction of the positive q-axis. The illustrated three-phase Ständerstromvertei ^¬ ment is therefore also referred to as a positive q-current or positive cross-current I _q . A positive cross current (+) I _q thus generates a positive motor torque M, while a negative cross current (-) I _q generates a braking regenerative torque.

As a result of the sunk arrangement of the existing of the magnetic material AlNiCo or FeCrCo permanent magnets 6 in the rotor 4 is achieved that generated by the cross-current I _q field in the air gap 3, the permanent magnets 6, ie their magnetization ^¬ state practically not affected. The reason for this is that the stator field generated by the transverse current I _q essentially enters the rotor yoke 4 ^λ adjacent to the rotor magnet 6. For magnetic reversal of the permanent magnets 6, however, the magnetic field of the rotor 4 is expediently to be influenced exclusively on the basis of the longitudinal current I _d . This longitudinal flow I _d , _which is also referred to below as the magnetizing current, thus represents the field-forming current.

On the other hand, a required torque M is to be generated by means of the transverse current I _q , which is accordingly also referred to as a torque-generating current. By the recessed An ^¬ 6 arrangement of the permanent magnets of said magnetic material AlNiCo or FeCrCo is the magnetization level or - changed or influenced. By the arrangement and combination of materials of the permanent magnets 6, therefore, a particularly ex ^¬ file and almost exclusively along current controlled ^¬ A position of the magnetization level or state ER ranges.

In order to obtain the smallest possible transverse inductance, non-magnetic or non-magnetic flow barriers 12 are inserted into the rotor 4, ie in its rotor material. The number s of the flow barriers 12 corresponds to the number of permanent magnets 6 with s = 2. The use of the flow barriers 12 and the lowering of the transverse inductance thereby achieved mean that the synchronous machine is also at medium and high rotational speeds 1 sufficiently high cross currents I _{q can be} imprinted to achieve the desired torques M.

The rectangular shape of the permanent magnets 6 allows - in contrast to trapezoidal spoke magnets - a uniform magnetization and demagnetization of the entire magnet volume of the permanent magnets 6 of the rotor 4. When fully magnetized rotor 4 are consequently magnetized all magnet regions of the permanent magnets 6 and therefore also of the rotor material. This is particularly advantageous with regard to the height of the runner field and the achievable torque M.

The radial or relatively deep recessed arrangement of the permanent magnets 6 in the rotor material or in the rotor 4 ensures reliable protection of the permanent magnet 6 against unwanted magnetization reversal by the armature transverse field, ie by the transverse field of the stator 2. The Magnetab ^¬ covers 10, their use is essentially constructive, have virtually no influence on the electro ^¬ magnetic ^{performance of} the synchronous machine. 1

While in the embodiment of FIG 3, the flow barriers 12 are rectangular, in the embodiment of FIG 2, the flow barriers 12 are triangular. In this case, the respective ge triangular tip 13 to the air gap 3 out. Also conceivable are other variants and geometric shapes of the river barriers 12. Also, the river barriers 12 can be omitted.

In the embodiment according to FIG. 3, the synchronous machine 1 is designed with a break hole winding on the stator side. This means that, in contrast to the embodiments according to FIGS. 1 and 2, in which the number of holes q = 2 is integral with each winding strand, in each case two slots per pole, in the embodiment according to FIG. 3 a broken number of holes q = 2.5. The stator 2 shown there has a total of fifteen stator slots ± U, ± V, ± W and therefore 7.5 stator slots per pole. The embodiment of the synchronous machine 1 with such a break hole winding is particularly advantageous when used in a hybrid vehicle or motor vehicle.

4 shows in a block diagram a regulation or control structure for operating a motor, also known as VP-variable below a permanently excited synchronous ^machine 1 in a hybrid application. The VP motor 1 is operated via a device 14 for controlling or control of a vehicle electrical system battery 15 of the vehicle with a battery voltage of, for example, 14V. By the arrow 16 15 optionally connected further Ver ^¬ consumers are indicated to this battery.

According to this comparatively detailed dargestell ^¬ in FIG 5 th overall structure of the synchronous machine works 1, the rotor 4 is preferably in accordance with the embodiments of

Figures 1 to 3 with recessed in the rotor material duration Magne ^¬ th 6 is made of AlNiCo magnet material than sogenann ^¬ ter 14V integrated starter-generator (14 V ISG) with VP-motor 1. The expediently electronic control or Rege- The device 14 comprises a three-phase inverter 17, which is connected to the battery 15 via a smoothing capacitor 18 on the input or DC side. On the output side, the inverter 17 is at output or Motor terminals 19 out, to which the VP motor 1 is connected.

A control or regulation unit 20 is supplied by a coupled to the VP motor 1 position sensor 21 information regarding the position of the rotor 4 (rotor position) as rotor position signal θ. As additional input information, the Re ^¬ gel unit 20 receives the phase currents i _σ, i _v, iw than corresponding actual values (FIG 5). Since the VP-motor 1 performs excluded in a star connection (Fig 1), the measurement of two phase currents from ^¬ is sufficient, because the third phase current can be calculated from the other two phase currents. In addition, the control unit 20 communicates in a manner not shown with a superordinate control or regulation unit of the hybrid vehicle, which is referred to below as the central vehicle control, via a field bus 22, for example via a so-called CAN bus (Controller Area Network). The central vehicle control unit provides the control unit 20 with a torque setpoint value M _w and the control unit 20 then provides the corresponding torque or the corresponding torque actual value M _actual (FIG. 5) to the shaft (not shown) of the engine 1.

Conversely, the ISG system shown in FIG. 4 supplies current status messages, in particular in the form of parameters, such as the current temperature of the stator windings U, V, W, to the higher-level vehicle control system via the fieldbus 22.

In the operation of the control, which is explained in greater detail below with reference to the block diagram of FIG. 5, the variables entered there are to be regarded as time variables and thus as instantaneous values. On the output side, the control unit 20 predefines the three manipulated variables Uτ _JS , u _V s and u _ws for the three stator voltages of the respective stator windings U, V and W. These manipulated variables u _us, u _V s and u are _ws direction by means of a ^¬ A 23 to the pulse width modulation (PWM) in the actual borrowed, current or instantaneous stator voltages u _σ , Uv or u _w .

In the present exemplary embodiment, this conversion takes place via a power electronic converter 24 connected downstream of the PWM device 23, also referred to below as power electronics. The stator voltages u _σ , u _v , u _w are applied to the output or motor terminals 19 of the VP motor 1 , so that appropriate strand currents ig, i _v and i _w in the respective winding strands U, V and W set. Of the three phase currents i _σ, i _v and i _w are 25, two phase currents using current transformer - in the execution example ^¬ the phase currents i _v and i _w - measured. The third phase current i _σ is calculated by means of negative addition from the two other phase currents i _v , i _w .

The control unit 20 thus has available the phase currents i _σ , i _v and i _w as well as the rotor position angle θ measured by means of the position sensor 21. As a further input quantity, the control unit 20 receives the torque setpoint M _w via the fieldbus 22. A positive sign of this desired value ^¬ M _w signifies motor operation, while a negative sign of this target value M _w regenerative operation of the synchronous machine 1 means.

The central component of the control unit 20 is the feldorien ^¬ oriented control, that is a control or function block 26 to the so-called field-oriented control. Field orientation means at the rotor field and thus oriented at the d-axis. The field-oriented control 26 thus operates in the runner-fixed dq coordinates. For this purpose, the position sensor 21 shows the position or angular position of the d-axis and thus the position of the rotor field on the basis of the position angle θ. In the sta tionary ^¬ operation then all the electric and magnetic time quantities at a synchronous speed n rotate, during this time sizes resting relative to the dq coordinate system. The reason for this is that this dq coordinate system also rotates at synchronous speed n. In the dq coordinate Therefore, constant values are obtained for steady-state operation, where a steady-state constant torque M _{lst is equivalent} to a constant cross-flow i _q .

To strengthen or weaken the permanent magnetic field of the rotor 4 of the VP motor 1, a positive or negative longitudinal current (+) i _d or (-) i _{d is} given for a short time. Although a corresponding current pulse i _d for the up, down or remagnetization of the permanent magnets 6 of the VP motor 1 is relatively high in magnitude, the time duration t of this pulse i _{d is} so short that the required energy is negligible.

For transfer of the permanent magnets 6 in their fully up magnetized magnetization state of the magnetization can approximate energy to below 30Ws with an active pulse duration in ^¬ t of t = about 5 ms can be reduced. Overall, with the exception of a few magnetization and demagnetization pulses i _d , the VP motor 1 is operated essentially only with the torque-forming transverse current i _q . This leads to a considerable increase in the system efficiency ^¬ degree at medium and high speeds n.

Within the control unit 20 based on the rotor position angle θ ^¬ and the three phase currents i _σ, i _v, iw by means of coordination dinatentransformation the current-axis current i _d and the current cross-current i _q calculated. An evaluation device 27 determines by means of a special control algorithm ^¬ of the torque command value M _w hand corresponding setpoints idw i _qw and for the pulse-shaped axis current i _d and the cross Ström i _q. The control algorithm of the evaluation device 27 takes into account in particular the actual values i _d and i _{q of} the longitudinal or transverse flow. On the basis of a comparison of the current setpoints i _dw and i _q "with the associated actual values i _d and i _{q, the} field-oriented control 26 outputs desired values for the longitudinal voltage u _d or the transverse voltage u _q . These setpoint values u ^¬ _d and Rotorlagewin kels ^¬ θ _ws means of coordinate transformation in the manipulated variables Uus, Uvs and u of the three stator voltages u _q with the aid converted. The coordinate transformation for determining the current longitudinal current i _d and the current cross-current i _q - and thus of the corresponding actual values i _d and i _q - by means of the function block 28 the coordinate transformation to Be ^¬ humor of the manipulated variables Uτ _JS, u _V s and u _ws takes place by means of the function _module 29.

Since the rotor 4 is due to the AlNiCo magnetic material of the permanent magnets 6 relatively easy to abmagnetisierbar and demagnetizable, the permanent magnetic rotor field, ie the magnetic ^¬ field of the rotor 4 can be adjusted in its height. The Ver ^¬ position of the rotor field is carried out essentially as a function of the speed n of the synchronous machine or the VP motor 1. While at comparatively low speeds nθ to nl (FIG 7), the VP motor 1 operates with maximum rotor field, is with increasing speed nl, n2, n3 the rotor field by reversal magnetization of the permanent magnets 6 increasingly from ^¬ lowered. The current speed n of the VP motor 1 can be determined from the change in the rotor position θ.

The remagnetization of the permanent magnets 6 is carried out according to the illustration of FIG 7, preferably in discrete stages. 7 shows the magnetization level of the rotor 4 shows Ψ n as a function of speed. In this case, the quantity indicated on the ordinate (y-axis) magnetization level Ψ au ^¬ is ßerhalb certain speed ranges .DELTA.n lowered stepwise or raised. In this case, the magnetization level Ψo indicates the fully magnetized state of magnetization of the permanent magnets 6 and thus of the permanent magnetic rotor 4. The magnetization levels .psi.i, Ψ ₂ Ψ ₃ indicate increasingly redu at ^¬ ed states of magnetization of the permanent magnets. 6 The Um ^¬ magnetization between these magnetization states or levels is effected by the short-term, pulse-like longitudinal currents i _d in the existing three-phase stator winding U, V, W. These winding-specific Ummagnetisierungsströme or longitudinal currents i _d differ in their spatial phase position - and thus in their phase relative to the detected by the position sensor 21 angular position θ of the rotor 4 - of the torque-forming cross currents i _q in the stator windings U, V, W of the stator. 2 the torque-forming cross-currents i _q thereby produce a magnetic field perpendicular to Magne ^¬ tisierungsrichtung of the rotor 4, while the ummagnetisie- in power field-forming longitudinal currents I magnetize _d in the direction of the rotor 4, and thereby the permanent magnetic field of the Läu ^¬ fers 4 (rotor field) selectively influenced. A negative longitudinal current (-) I _d leads to the demagnetization of the duration ^¬ magnets 6, while a positive longitudinal current (+) I _d to ^¬ magnetization of the permanent magnet 6 and thus the rotor 4 leads. As the rotational speed n increases, the permanent magnets 6 are thus increasingly removed, so that a corresponding field weakening is achieved with increasing rotational speed n.

According to the illustration in FIG. 7, the VP motor 1 thus operates at comparatively low rotational speeds n in the range between nθ and nl (nθ <n <nl) with fully magnetized permanent magnet 6. In middle rotational speed ranges between n1 and n2 or between n2 and n3 (nl <n <n3) and at relatively high speeds in excess of n3 (n> n3) of the ar- VP-1 beitet motor with a comparatively low Magneti ^¬ sierungsniveau of the permanent magnets. 6

To compensate for the so-called memory effect of the permanent magnets 6 and thus of the permanent magnetic rotor 4 is carried out by means of the control algorithm of the evaluation 27 an at least two-stage setting of Magnetisie ^¬ tion state of the permanent magnets 6 in response to the ak ^¬ tual speed n. This is in a first stage an amplitude-shaped longitudinal flow i _d of the control unit 20 such set and the winding strands U, V, W of the stator 2 imprinted that the permanent magnets 6 are first at least approximately fully magnetized ^¬ . This corresponds to a reset function which always leads to a definite nierten initial state of the magnetization level of the duration ^¬ magnets 6 of the rotor 4 leads. Only in a subsequent stage, at least one further pulse-like longitudinal current i _d the winding strands U, V, W of the stator 2 impressed to the permanent magnets 6 and thus the rotor 4 according to the desired or required degree of field weakening or field gain as a function of the current speed n umzumagnetisieren, ie off or aufzumagnetisieren.

The mode of action of the reset function for compensating for the reminder effect can be illustrated with reference to the BH diagrams shown in FIGS. 8 and 9 with the hysteresis curves of the AlNiCo magnetic material of the permanent magnets 6 shown therein in detail. By the numerals (1) and (1 ^*) in FIG 8 are different starting states of magnetization or indicated levels of such a magnetic material is ^¬. Their retentivity or Remanzinduktion is along the magnetic induction B indicating ordinate (y-axis) as well ^¬ magnitude and in terms of the sub direction different. Therefore, a magnetization reversal requires various Koerzitivfeidstärken and consequently differing ^¬ che field strength H of a force acting on the AlNiCo permanent magnet 6 external magnetic field, that is, the forces acting on the Läußer 4 and thus to the permanent magnets 6 stator rotating field of the VP-motor. 1

Based on these different output states, the same longitudinal current i _{d would} lead to different magnetization states of the permanent magnets 6. In order to avoid this the, in the first stage by means of the control unit 20 to the next ^¬ a pulse-like direct-axis current i _d - _m a _x set, leading to a fully magnetized state of the permanent magnets. 6 As a result, in the first stage, regardless of the initial state (1) and (1 ^* ), the magnetization state indicated by the numeral (2) always sets in. If this axis current i _d - _m a _x after a set corresponding to the pulse-duration-off ^¬ t, arises of the numeral (4) indicated magnetization state regardless of the starting state ^¬ (1) or (1 ^* ) of the permanent magnet 6 a.

By means of this reset function during the first step of impressing a pulse-shaped longitudinal current i _d to the STAs ^¬ of winding U, V, W can be virtually any desired operating point, for example, a angedeu ^¬ by the numeral (3) preparing operating on the by the numeral (5) indicated magnetization state can be achieved with a defined demagnetizing longitudinal flow i _d during the second stage.

As shown by the illustration according illustrates FIG 9, this reset function leads also to the fact that single or in different magnetization states radial magnetic layers of the permanent magnets 6 by the initiated during the first stage magnetization or longitudinal current i _d - _m a _x all the magnetic layers of the permanent magnet 6 are converted into an at least approximately the same fully magnetized magnetization state. The initial and final magnetization states under ^¬ different radial magnetic layers are in turn indicated by the numerals (1) and (2). Thus, all the magnetic layers reach the permanent magnets 6 independently of the output state (1) or (2) along the longitudinal Hystereseverlaufes when the current i _d - _m a _x on the corresponding Hystereselinie the state of complete magnetization. If the initiated during the first stage axis current i _d - _m a _x after the In ^¬ pulse duration off t, so reach the different magnetic layer in the second quadrant of the BH diagram of Figure 9 again by the numerals (1) and (2) indicated

Magnetization states along the same course of the maxi ^¬ outer outer hysteresis (reset done). Accordingly, by means of a defined longitudinal current i _d during the second stage for all magnetic layers of the permanent magnet 6 different borrowed, but reproducible magnetization states inde ^¬ independently achieved from the initial state. The control strategy described with two-stage Aufprä ^¬ tion of the magnetization state of a variable permagnetagnetic rotor 4 changing pulse-shaped longitudinal current i _d on the stator winding U, V, W synchronous machine 1 leads already to a significantly improved performance at medium and high speeds n, when the rotor-side permanent magnets are not or relatively little sunk in the rotor or rotor material arranged. The described two-stage control strategy is therefore advantageously also in other embodiments of the rotor, for example with surface magnets or with trapezoidal spoke magnets.

Claims

claims

1. Permanent-magnet synchronous machine (1) with a stator winding for producing a rotating field exhibiting the stator (2), which forms an air gap (3) a permanent magnetic rotor material having rotor (4), in which a number of means of a field-forming Longitudinal current (i _d ) are integrated and demagnetizable permanent magnets (6), wherein the permanent magnets (6) in the rotor (4) or in the rotor material (4 ^λ ) are arranged sunk.

2. Synchronous machine according to claim 1, characterized in that the permanent magnets (6) in the finer material (4 ^λ ) are arranged like a spoke.

3. Synchronous machine according to claim 1 or 2, characterized in that the permanent magnets (6) have a relation to the radial rotor material thickness (a) small radial dimension (d).

4. Synchronous machine according to one of claims 1 to 3, characterized in that the permanent magnets (6) to form a radial distance (c) to the air gap (3) in the permanent-magnetic rotor material (4 ^λ ) are used.

5. Synchronous machine according to one of claims 1 to 4, characterized in that the permanent magnets (6) are four ^¬ angular, in particular rectangular or square.

6. Synchronous machine according to claim 4, characterized in that the permanent magnets (6) with de ^¬ ren longitudinal side facing the air gap (3).

7. Synchronous machine according to one of claims 1 to 6, characterized in that the permanent magnets (6) to the air gap (3) are concealed out.

8. Synchronous machine according to claim 7, characterized in that the permanent magnets (6) are covered with ^{¬ means of} non-magnetic covers (10).

9. Synchronous machine according to one of claims 1 to 8, characterized in that in the rotor material (4 ^λ ) one of the number of permanent magnets (6) corresponding number of along the circumference of the rotor (4) extending receiving grooves (7) for receiving the permanent magnets (6) are provided.

10. Synchronous machine according to claim 9, characterized in that the clear width of the receiving grooves (7) in the region of the groove bottom is greater than or equal to the clear width in the region of the air gap (3) facing slot opening.

11. Synchronous machine according to claim 9 or 10, characterized in that the receiving grooves (7) are formed stepwise to form two receiving spaces, where ^¬ in the permanent magnets (6) in the air gap (3) facing away from the receiving space of the respective receiving groove (7) einliegen.

12. Synchronous machine according to one of claims 1 to 11, characterized in that on the circumference of the rotor (4) a number of flow barriers (12) are arranged for lowering a transverse inductance.

13. Synchronous machine according to claim 12, characterized in that the flow barriers (12) are rectangular.

14. Synchronous machine according to claim 12, characterized in that the flow barriers (12) are triangular-shaped.

15. Synchronous machine according to claim 14, characterized in that the flow barriers (12) with the air gap (3) directed towards, preferably at this immediately adjacent, triangular tip (13) in the rotor (4) are arranged.

16. Synchronous machine according to one of claims 1 to 15, characterized in that the magnetic material of the Dau ^¬ ermagnete (6) AlNiCo or FeCrCo is.

17. Synchronous machine according to one of claims 1 to 16, characterized in that one of the number of poles (2p) ent ^¬ speaking number of permanent magnets (6) distributed on the circumference of the rotor (4) is arranged.

18. Synchronous machine according to one of claims 1 to 17, characterized by between the permanent magnet (6) arranged laminated cores or rotor yokes (4 ^λ ) for guiding the magnetic flux.

19. Synchronous machine according to one of claims 1 to 18, characterized in that the permanent magnets (6) are magnetized in the direction of the circumference of the rotor (4).

20. Synchronous machine according to one of claims 1 to 19, characterized in that the stator winding is designed as a broken hole winding.

21. Use of a variably permanent-magnet synchronous machine (1) according to one of claims 1 to 20 as a motor for generating torque or as a generator for generating power in a hybrid vehicle.

22. A method for operating a variably permanent magnet synchronous machine (1), in particular according to one of Ansprü ^¬ che 1 to 20, with a stator (2) having a rotating field generating stator winding (U, V, W), and with a rotor (4 ) with integrated permanent magnets (6), wherein the stator winding for setting the magnetization state of the rotor-side permanent magnets (6) a particular pulse-like longitudinal flow (i _d ) is impressed at least two stages, - wherein in a first stage, the permanent magnets (6) to ^{¬ at} least approximately completely magnetized, and wherein in a second Stage the permanent magnets (6) re-magnetized or at least partially demagnetized.

23. The method of claim 22, wherein by means of field-oriented control (26) based on a rotor-fixed dq coordinate system, a torque-forming cross-flow (i _q ) and / or a magnetization of the permanent magnets (6) serving field-forming longitudinal flow (i _d ) for field weakening as needed or field gain is set.

24. The method of claim 22 or 23, wherein in the second stage the degree of magnetization of the permanent magnets

(6) depending on at least one Betriebspara ^¬ meter, in particular a desired torque (M _w ), the rotational speed (n) and / or the attitude angle (θ) of the rotor

(4).

25. Apparatus for operating, regulating or controlling a variably permanently excited synchronous machine (1), in particular a VP motor in a hybrid vehicle, having a stator winding with a number of winding strands (U, V, W) stand (2), with a provided with variably magnetizable permanent magnet (6) rotor (4), and with a control unit (20) by means of feldorien--oriented control (26) and a one of at least two ^¬-stage pulse-like longitudinal current (i _d) adjusting control algorithm (27) based on input information for the rotor position (θ) of the rotor (4) and for the actual Values (i _u, i _v, i _w) of phase currents of the stator winding by presetting a desired torque value (M _w) adjusting ^¬ sizes (UUS, Uvs, u _ws) for setting voltage values (Ug, U v and u _w) the winding strands (U, V, W) generate.

26. The apparatus of claim 25, wherein the control algorithm (27) based on the torque setpoint (M _w ) and the actual value (i _d ) of the field-forming longitudinal current and an actual value (i _q ) of a torque-forming cross-flow setpoint (i _dw ) for determines the longitudinal flow and a setpoint (i _q ") for the cross flow.

27. The apparatus of claim 25 or 26, wherein the field-oriented control (26) based on a comparison of

Actual value (i _d) and the reference value (IDW) of the longitudinal current on the one hand and on the basis of a comparison of the actual value (i _q), and the nominal value (i _q ") of the cross current on the other hand set values (u _d, u _q) for the longitudinal and transverse voltage output.

28. Device according to claim 27, ^wherein a function ^{block ¬} (29) for coordinate transformation based on the rotor position (θ) the setpoint value (u _d ) for the longitudinal voltage or the desired value (u _q ) for the transverse voltage in the manipulated variables (uus, Uvs? U _WS ).

29. Device according to one of claims 25 to 28, wherein a function block (28) for coordinate transformation based on the rotor position (θ) and the actual values (i _u , i _v , i _w ) of the phase currents, the longitudinal current actual value (i _d ) and the cross ^¬ actual current value (i _q) is determined.

30. Device according to one of claims 25 to 29, comprising means (23) for pulse width modulation (PWM) and with a power electronic converter (24) for converting the manipulated variables (uu _S , Uvs _/ U _BS ) in the voltage values

(Ug, Uv, Uw).