DE102007018734A1 - Electrical machine for use as e.g. rear axle, for motor vehicle, has engine rotor supported along perfect axial direction relative to adjustable squirrel cage winding and another rotor, and switching arrangement enabling current flow - Google Patents

Abstract

The machine (1) has an engine rotor (11) rotatably supported at a perfect axial direction (7). Permanent-magnets are distributedly arranged along a circumference and exhibiting alternate polarity, where the circumference is concentric with the perfect axial direction. An engine rotor (9) is relocatably supported along the perfect axial direction relative to an adjustable squirrel cage winding and the engine rotor (11). A switching arrangement (5) enables current flow in the adjustable winding based on angle positions of the engine rotors. An independent claim is also included for a method for controlling an electrical machine.

Description

The The invention relates to an electric machine comprising a rotatable mounted motor rotor, which rotates about an excellent axial direction is and having a changing polarity, along comprises permanent magnets distributed around a circumference, the circumference concentric with the excellent axial direction is, which is a rotation axis of the motor rotor, a stator with at least one switchable by means of a circuit arrangement short-circuit winding and the circuit arrangement. The invention further relates to a use Such an electrical machine and a method of operation an electric machine.

Out Many electrical machines are known in the prior art for driving rotating axles, for example motor vehicle axles, be used. In the course of considerations, how a saving fossil energy source is possible, is increasingly over Hybrid propulsion systems thought, in which an internal combustion engine is coupled with an electric machine. The electric Machine can on the one hand as a drive, for example a motor vehicle, used and on the other hand as a generator be used to kinetic energy of the vehicle during a deceleration process into electrical energy, which is then stored in an energy store, For example, a battery can be stored. Such a Operation is referred to in a motor vehicle as recuperation.

It There are many different concepts, an electric machine to couple to an internal combustion engine. In a so-called single-shaft parallel hybrid drive is an internal combustion engine via a separating clutch with mechanically connected to the electrical machine. This is again about a transmission connected to the output shaft of the drive train. The electric machine can both provide torque in addition to that provided by the internal combustion engine Torque (closed disconnect clutch), to exclusive Providing drive torque for the output shaft (open disconnect clutch) or as a generator, both driven by the internal combustion engine while driving as also during a recuperation process with the disconnect clutch open, be used. In addition, the electric machine used to attach a crankshaft to the internal combustion engine to accelerate a starting process of the internal combustion engine.

at a serial hybrid propulsion system is the internal combustion engine Coupled with a generator, that of the combustion engine provided kinetic energy converts into electrical energy. This is powered by another electric machine, which acts as a drive motor used, converted back to kinetic energy, which drives an output shaft.

Out The prior art is a variety of other hybrid concepts known.

For example, a drive concept of Volkswagen AG is known in which the electric machine and the transmission of a single-shaft parallel hybrid drive are replaced by a so-called Magneto-Electric Gearboxes (MEGA). The principle of such a generator-electric motor combination is for example from the DE 44 08 719 C1 known, which is useful as an electromagnetic torque converter or electromagnetic transmission with large spread, for example, in a motor vehicle with hybrid drive structure. For the realization of such an electric machine there is proposed to fix on a connected to an internal combustion engine input shaft a hollow cylindrical generator rotor and to install on a output shaft a hollow cylindrical electric motor rotor, both rotors having on its inner side circumferentially distributed permanent magnets with alternating polarity. In addition, a stator with at least one switchable short-circuit winding is provided, in which the short-circuit winding is displaceably arranged by means of a guiding and displacement device under the permanent magnets of the rotors within wide ranges. With the help of magnetic field sensors between the permanent magnets, the polarity of opposing permanent magnets is determined and the short-circuit winding is closed or opened as a function of sensor signals. In this way, the direction of rotation of the output shaft can be adjusted, while the positioning of the short-circuit winding under the permanent magnet of the motor and generator rotor determines the speed and the output torque of the output shaft.

The in the DE 44 08719 C1 proposed embodiment has in each case bell-shaped generator and electric motor rotors which enclose an inner and displaceable along the coaxially oriented directions of rotation of the rotors stator. In order to dissipate the heat losses occurring during operation in the stator, it is necessary to provide the stator with an active cooling.

One possible embodiment of such a stator is in the DE 100 10 028 A1 described. There is a stator of an electric machine, in particular an electrical transmission, described, which is completely made of several stories one above the other th and interconnected metal layers consists. The individual sheets are shaped such that they have grooves for receiving at least one stator winding and preferably also water channel openings and openings for the storage and moment support and optionally axial displacement of the stator.

Out Weight reasons, in particular a thickness of the magnetic Conclusion in the rotors, one is possible high number of poles sought. Therefore, the structure of a stator for a known generator-motor combination complicated and expensive. Furthermore, there is regular in the known stators the danger that is due to thermal heating in the stator expansions that give a crack to an inside executed cooling jacket. In such a Case, a heat conduction is interrupted and it exists the risk of overheating and damage the windings of the stator. Therefore, in construction and Manufacturing special quality standards are achieved the one manufacture of the stators and a total of the generator-motor combination expensive.

A preferred circuit of the short-circuit winding is in the DE 102 37 451 A1 described. There, a method for switching currents in a stator winding of a generator-electric motor combination is described, wherein the stator winding has at least one winding which is short-circuited or high impedance switchable by at least one device, wherein the at least one winding is connected to a capacitor by means of whose voltage peaks are reducible due to switching operations and energy stored in the stator winding is temporarily stored, wherein between the winding and the capacitor at least one switchable decoupling element is arranged, said about the decoupling the zwischenzuspeichernde energy due to the shutdown of the device in a non-power cycle as a charging current the capacitor is dissipated and the cached energy can be fed back as a working current in the working cycle in the stator winding, wherein the decoupling element is controlled in time during the recovery in such a way that the K capacitor voltage does not drop below a specified voltage level.

coupled one the capacitor via a power electronics and / or a DC / DC converter, the generator-motor combination can deprive energy and be stored in a battery of energy or the generator-motor combination Energy from the battery can be supplied to, for example, over To drive the motor rotor, the output shaft electrically.

The Although the familiar MEGA drive concept offers a number of advantages, Such a generator-electric motor combination can be but only for certain hybrid propulsion concepts use.

task The invention is therefore an electric machine for to provide a drive system, in particular a motor vehicle, with a weight saving and constructive simplification of a Powertrain can be realized. In particular, an improvement sought for propulsion systems, in which preferably Coaxially arranged shafts with different torques or Speeds should be driven.

The Object is achieved by an electrical Machine with the features of claim 1, a use with the features of claim 12 and a method for Controlling an electrical machine with the features of the claim 12 solved. Advantageous embodiments of the invention result from the dependent claims.

Here, it is provided to further develop an aforementioned electric machine so that coaxially with the excellent axial direction defined by the rotation axis of the motor rotor, another motor rotor rotatably supported along the excellent axial direction adjacent to the motor rotor is also supported a further alternating polarity, distributed along a further circumference arranged distributed further permanent magnets, wherein the further circumference is concentric with the excellent axial direction, ie the axis of rotation of the motor rotor, and wherein the motor rotor along the excellent axial direction relative to the at least one switchable short-circuit winding and the further motor rotor is displaceably mounted, and the switching arrangement can enable a current flow in the at least one short-circuit winding in dependence on the positions of the motor rotor and the further motor rotor. This means that an electric machine is provided in which an effective conductor length of the at least one short-circuit winding in the magnetic field generated by the permanent magnets of the motor rotor is variable by a displacement of the motor rotor along the excellent axial direction. This is a moment that can exert the electric motor on the motor rotor, or a speed of the motor rotor adjustable. A change in the effective conductor length of the at least one short-circuit winding can be varied independently of an effective conductor length of the at least one short-circuit winding in the magnetic field of the further motor rotor. This makes it possible to transmit to the motor rotor and the other motor rotor different torques during operation of the electric machine. Therefore, the invention is elektri cal machine as final drive and / or recuperation, in particular a non-actively steered axle, preferably a rear axle, in a land vehicle, in particular a motor vehicle. When using the electric machine according to the invention as a drive unit of a non-actively steered rear axle of a motor vehicle so an otherwise needed differential can be saved. If an internal combustion engine is arranged in the front region of the motor vehicle, ie adjacent to the front axle, a propeller shaft for transmitting mechanical energy along a longitudinal axis of the motor vehicle can additionally be saved. The use of the electric machine according to the invention is thus particularly suitable in serial hybrid drive concepts.

It is thus provided, the electrical machine by means of a method to be controlled so that by switching the circuit arrangement in dependence from the angular positions of the motor rotor and the further motor rotor the directions of rotation of the motor rotor and the other motor rotor be controlled and in addition a ratio a torque transmission to the motor rotor and the further motor rotor by a displacement of the motor rotor relative to the at least one short-circuit winding and the further motor rotor is regulated.

A improved controllability is achieved in a further development of Invention, in addition to the further motor rotor independently from the motor rotor relative to the excellent axial direction slidably mounted to the at least one switchable winding is. This means that both the motor rotor and the other Motor rotor relative to the at least one short-circuit winding of the Stators slidably mounted along the excellent axis direction are. Thus, effective conductor lengths in the at least one short circuit winding in the magnetic field of the motor rotor as well as the other motor rotor can be variably adjusted. About here can be the speeds or torques that the motor rotors transferred to their respective output shafts, regulated become.

Across from the known from the MEGA concept electric machines leaves To significantly reduce a design effort when the stator is formed hollow cylindrical and the motor rotor and / or the further motor rotor are designed as internal rotor. One Rotor designed as an internal rotor can be designed store much easier than a bell-shaped Rotor.

are Both the motor rotor and the other motor rotor as an internal rotor formed, so there is the additional advantage that the stator by means of an externally applied cooling jacket can be cooled. Does it come to a warming of the stator due to copper or iron losses in the stator, so The stator expands against the surrounding cooling jacket out. This ensures that always a good thermal contact exists between the stator and the cooling jacket and a reliable cooling guaranteed at all times is. As a result, a reliability of the electrical machine increased.

Preferably be the motor rotor, the other motor rotor, the stator and the Circuit arrangement arranged in a common housing. As a result, a compact design is achieved. The housing is preferably designed to be in an engine compartment or exposed under an underbody of a motor vehicle can be.

at In a preferred embodiment, the stator is fixed with connected to the housing and the motor rotor and the other Motor rotor are each relatively displaceable to the housing arranged.

at a particularly preferred embodiment of the invention the motor rotor and the further motor rotor are identical or mirror-image formed to each other and in particular have an identical number of alternating polarity permanent magnets same dimension, arrangement and remanent magnetization on. hereby is achieved that with identical overlap with the transmit at least one short-circuit identical moments become. This will make a calculation that will be executed in the course of the control is, simplified. For example, only a calculation formula or a table needed to get that for a position relative to the longitudinal axis effective moment transfer to calculate.

Preferably are the motor rotor and the other motor rotor in terms of at least one switchable short-circuit winding arranged slidably so that equal overlap areas between the at least one short-circuit winding the permanent magnet the motor rotor on the one hand and the at least one short-circuit winding the other permanent magnet of the other motor rotor on the other are adjustable. This means that same effective conductor lengths of the at least one short-circuit winding in the magnetic fields of the two Rotors are feasible. Preferably, the electric machine designed so that all possible effective conductor lengths, the can be realized for the motor rotor, also at the same time for the other motor rotor. hereby can be a symmetrical drive, for example a rear axle, be realized when driving straight ahead.

Furthermore, a displacement mechanism ge which symmetrically moves, with a first actuator, the two rotors in opposite directions along the excellent axial direction to symmetrically vary the effective conductor lengths. A second drive may be provided which shifts the motor rotor relative to the further motor rotor along the excellent axis direction such that asymmetrical, ie unequal, conductor lengths of the at least one short circuit winding with respect to the two motor rotors results. This means that small speed differences can be realized by the second actuator and the first actuator regulates a rough speed specification for both motor rotors.

at another preferred embodiment is provided that with the motor rotor, an actuator for moving the motor rotor along the excellent axis direction and with the other motor rotor another actuator for moving the other motor rotor coupled along the excellent axis direction is independent each other a speed of the motor rotor and a torque transmission to the motor rotor and a speed of the further motor rotor and a Speed transmission to the other motor rotor to regulate can. This is an individual speed or torque transmission to the two with the motor rotors connected output shafts possible.

Becomes additionally with the at least one winding over a switching arrangement at least one energy storage connected and provided another control device, this is advantageous to an electric motor drive of the motor and or further Motors and a recuperation of the motor rotor and / or the enable further motor rotor kinetic energy acting.

Around an improved running behavior of the motor rotor and further Motor rotor to obtain, d. H. a pulsating momentum transfer, the usual for switched electric machines is to even, is at a preferred Embodiment provided that the stator several separately includes switchable short-circuit windings.

Around Detect the positions of the motor rotor and the other motor rotor To be able to, is in a preferred embodiment provided that magnetic field sensors between the permanent magnets are arranged so that they each have a magnetic pole orientation of the other motor rotor can detect.

at a preferred procedure for operating a novel electric machine is provided that the motor rotor and / or the other motor rotor along the excellent axis direction be moved relative to the at least one short-circuit winding, so that an active conductor length for a Interaction with that of the permanent magnets of the motor rotor generated magnetic field and / or further active conductor length the at least one short-circuit winding for an interaction with that of the other permanent magnets of the other motor rotor caused magnetic field, and over it a speed and a torque transmission of the motor rotor and / or the further motor rotor are controlled. this means a torque distribution on the two rotors or hereby connected Drive wheels. Due to the rotor displacement can both wheel drives both high speed and high torque machine be operated, resulting in a reduction of iron losses (or ohmic losses) in the electric machine.

The Invention will be described below with reference to a preferred embodiment explained in more detail with reference to a drawing. Hereby shows:

1 a schematic representation of an electric machine, in which a motor rotor and another motor rotor are each arranged independently of each other displaceable relative to a stator and each other.

The 1 schematically shows an electric machine 1 , The electric machine 1 includes a stator 3 , This is formed as a hollow cylinder. The stator 3 includes at least one by means of a circuit arrangement 5 switchable short-circuit winding (not shown). Preferably, the stator comprises 3 several short-circuit windings, which can be switched separately from each other. The circuit arrangement 5 is spatially adjacent to the stator 3 arranged. The separately configured short-circuit windings are also referred to as strands. A cylinder axis of the hollow cylindrical stator 3 sets an excellent axis direction 7 firmly.

Concentric to the excellent axial direction 7 are designed as an internal rotor motor rotor 9 and another motor rotor 11 independently rotatably mounted.

The motor rotor 9 and the other motor rotor 11 have cylindrical outer surfaces 13 . 15 on, the one inside 17 facing the stator. On the inside 17 the at least one short circuit winding is guided in not shown grooves. On the cylindrical outer surfaces 13 . 15 each permanent magnets are arranged (not shown). The permanent magnets are along a circumference or a further circumference (not shown) concentric with the excellent axial direction, each distributed in alternating polarity. In a preferred embodiment, the permanent magnets of the motor rotor 9 and the other motor rotor 11 along the excellent axis direction 7 an identical extent. In addition, have the permanent magnets of the motor rotor 9 and the other motor rotor 11 preferably the same remanence magnetization.

To the motor rotor 9 and the other motor rotor 11 to drive, by means of the circuit arrangement 5 connected in the at least one short-circuit winding causes a current flow. The energy required for this purpose, for example, an energy storage 19 , which is designed for example as a battery, removed and via a DC-DC converter 21 (DC / DC converter) supplied. The energy may also be provided by a generator driven by an internal combustion engine. The at least one short-circuit winding must by means of the circuit arrangement 5 be closed and opened at appropriate times. The opening and closing, that is to say the effecting of a current flow in the at least one short-circuit winding and the inhibition of a current flow, respectively depend on an angular position of the motor rotor 9 and the other motor rotor 11 to be done. To the positions or angular positions of the motor rotor 9 and the other motor rotor 11 To be able to determine, sensors are provided (not shown), which are preferably designed as magnetic sensors. These are preferably on the stator 3 arranged. In this case, they are preferably designed such that they have a polarization of the permanent magnets on the respective rotor relative to the polarization on the stator 3 can detect. In order to achieve an identical direction of rotation of the motor rotor and the other motor rotor, each having a same polarity permanent magnets must be connected via a line section of the at least one short-circuit winding while a current flows through them. If permanent magnets of different polarity are connected via a line section of the short-circuit winding, while a current flows through this line section, then an opposite direction of rotation of the motor rotor 9 and the other motor rotor 11 be achieved. Includes the stator 3 a plurality of separately switchable short-circuit windings, so in pairs further sensors may be provided to detect the angular positions of the rotors.

Is the electric machine 1 For example, installed in a motor vehicle so that the motor rotor 9 with a right rear wheel and the further motor rotor 11 are connected to a left rear wheel, so the electric machine can be used to drive these wheels. However, if the motor vehicle has kinetic energy and is to be decelerated, this kinetic energy can be generated by means of the electric machine 1 be converted back into electrical energy. This process is called recuperation. Here are the motor rotor 9 and the other motor rotor 11 operated as generators. The voltage induced in the at least one short-circuit winding leads to a current flow in the at least one short-circuit winding, if this again at suitable times as a function of the angular positions of the motor rotor 9 and the other motor rotor 11 closed and opened. The electrical energy can be through the DC-DC converter 21 in the energy store 19 be stored.

The motor rotor 9 and the other motor rotor 11 are thus as internal rotor of the stator 3 the electric machine 1 educated. The motor rotor 9 and the other motor rotor 11 are supported with respect to the excellent axial direction so as to be axially displaceable relative to each other and relative to the at least one short-circuit winding of the stator along the excellent axial direction 7 are. This creates the possibility of an effective conductor length of the at least one short-circuit winding in the of the permanent magnet of the motor rotor 9 or the further permanent magnet of the further motor rotor 11 to vary generated magnetic fields. By varying the effective conductor lengths, it is possible to independently set the rotational speeds of the motor rotor and the further motor rotor at a predetermined switching frequency. For this purpose, the motor rotor 9 with an actuator 23 and the other motor rotor 11 with another actuator 25 connected. These are over a rule unit 27 driven. Be the motor rotor 9 and the other motor rotor 11 parallel to the excellent axis direction 7 from a middle 29 of the stator 3 moved away, so increases the speed at which the motor rotor 9 and the other motor rotor 11 turn when the electric machine 1 is operated as a motor. Accordingly, a transmitted torque decreases. Be the motor rotor 9 and the other motor rotor 11 whereas to the middle 29 of the stator 3 , ie the center of the at least one short-circuit winding, moves, the speed decreases and a torque transmission increases.

The electric machine 1 is thus preferably used as a drive and / or recuperation unit. In particular, the electric machine 1 on a not actively steered axle, preferably a rear axle, a land vehicle, in particular a motor vehicle used. Under a non-actively steered axle is understood such an axis whose wheels are not a driver via steering means, such as a steering wheel, with respect a straight-ahead direction can turn. By using the electric machine as Hinterachsantriebs- and Rekuperationseinheit in a conventional motor vehicle whose front axle is steered, a propeller shaft and a rear differential can be saved. The electric machine is in this case operated so that the directions of rotation of the motor rotor and the other motor rotor are controlled by switching the circuit arrangement in dependence on the angular positions of the motor rotor and the other motor rotor. By means of the control unit, the motor rotor and / or the further motor rotor are displaced along the excellent axial direction relative to the at least one winding, so that a speed and a torque transmission of the motor rotor and / or the further motor rotor are controlled. The displacement along, ie parallel to, the excellent axial direction relative to the at least one winding causes an active conductor length to interact with the magnetic field generated by the permanent magnets of the motor rotor and / or further active conductor length of the at least one short-circuit winding for a Interaction with the magnetic field caused by the other permanent magnet of the other motor rotor changed. As explained above, this change causes a change in the rotational speed and the torque transmission of the respective motor rotor. This ensures that the electric machine can always be operated as close as possible to an optimum efficiency. The electric machine can thus achieve both a high torque transmission and a high speed with a very good efficiency. The same applies if the electric machine is operated as a generator during recuperation. A torque distribution on two axle halves or wheels can be adjusted electrically.

The described embodiment is merely exemplary. Other embodiments in which the motor rotor or the further motor rotor are operated as external rotor are also feasible. However, if both motor rotors are designed as internal rotors, then the stator 3 by means of an externally applied cooling jacket 31 be cooled. This offers the advantage that heating of the stator occurring due to iron losses and / or copper losses in the at least one short-circuit winding 3 this against the surrounding cooling jacket 31 expands and thus always optimal heat conduction from the stator 3 on the cooling jacket 31 is guaranteed. Thus, a possible overheating in the stator is avoided and created a high reliability and reliability of the electrical machine.

1

electrical machine

3

stator

5

circuitry

7

excellent axially

9

motor rotor

11

Another motor rotor

13

cylindrical Outside surface of the motor rotor

15

cylindrical Outer surface of the other motor rotor

17

inside of the stator

19

energy storage

21

DC converter

23

actuator

25

additional actuator

27

control unit

29

center of the stator

31

cooling jacket

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4408719 C1 [0006, 0007]
• - DE 10010028 A1 [0008]
• - DE 10237451 A1 [0010]

Claims (14)

Electric machine ( 1 ), comprising a rotatably mounted motor rotor ( 9 ), which has an excellent axial direction ( 7 ) is rotatable and comprises an alternating polarity distributed along a circumference arranged circular permanent magnets, wherein the circumference is concentric with the excellent axial direction, a stator ( 3 ) with at least one by means of a circuit arrangement ( 5 ) switchable short-circuit winding and the circuit arrangement ( 5 ), characterized in that coaxial to the excellent axial direction ( 7 ) another motor rotor ( 11 ) is rotatably mounted along the excellent axial direction ( 7 ) next to the motor rotor ( 9 ), and also having an alternating polarity distributed along a further circumference arranged arranged further permanent magnets, wherein the further circumference is concentric with the excellent axial direction, and wherein the motor rotor ( 9 ) along the excellent axis direction ( 7 ) relative to the at least one switchable short-circuit winding and the further motor rotor ( 11 ) is slidably mounted, and the switching arrangement ( 5 ) a current flow in the switchable winding in dependence on the angular positions of the motor rotor ( 9 ) and the further motor rotor ( 11 ). Electric machine ( 1 ) according to claim 1, characterized in that in addition the further motor rotor ( 11 ) independent of the motor rotor ( 9 ) along the excellent axis direction ( 7 ) is slidably mounted relative to the at least one switchable winding. Electric machine ( 1 ) according to claim 1 or 2, characterized in that the stator ( 3 ) is formed as a hollow cylinder and the motor rotor ( 9 ) and the further motor rotor ( 11 ) are designed as internal rotor. Electric machine ( 1 ) according to one of the preceding claims, characterized in that the motor rotor ( 9 ), the further motor rotor ( 11 ), the stator ( 3 ) and the circuit arrangement ( 5 ) are arranged in a common housing. Electric machine ( 1 ) according to one of the preceding claims, characterized in that the stator ( 3 ) is firmly connected to the housing and the motor rotor ( 9 ) and the further motor rotor ( 11 ) are each arranged relatively displaceable relative to the housing. Electric machine ( 1 ) according to one of the preceding claims, characterized in that the motor rotor ( 9 ) and the further motor rotor ( 11 ) are identical or mirror images of each other, in particular an identical number of alternating polarity having permanent magnet of the same dimensions, arrangement and remanent magnetization. Electric machine ( 1 ) according to one of the preceding claims, characterized in that the motor rotor ( 9 ) and the further motor rotor ( 11 ) are arranged displaceably in relation to the at least one switchable short-circuit winding such that overlapping areas of equal size between the at least one short-circuit winding and the permanent magnet of the motor rotor ( 9 ) on the one hand and the at least one short-circuit winding and the further permanent magnet of the further motor rotor ( 11 ) are adjustable on the other hand. Electric machine ( 1 ) according to one of the preceding claims, characterized in that with the motor rotor ( 9 ) an actuator ( 23 ) for moving the motor rotor ( 9 ) along the excellent axis direction ( 7 ) and with the further motor rotor ( 11 ) another actuator ( 25 ) for moving the further motor rotor ( 11 ) along the excellent axis direction ( 7 ) are coupled to independently of each other a speed of the motor rotor ( 9 ) and a torque transmission to the motor rotor ( 9 ) and a speed of the further motor rotor ( 11 ) and a speed transmission to the further motor rotor ( 11 ) to be able to regulate. Electric machine ( 1 ) according to one of the preceding claims, characterized in that the at least one short-circuit winding via the switching arrangement ( 5 ) with at least one energy store ( 19 ) and the circuit arrangement ( 5 ) is operable to an electric motor drive of the motor rotor ( 9 ) and / or the further motor rotor ( 11 ) and a recuperation of the motor rotor ( 9 ) and / or the further motor rotor ( 11 ) to enable acting kinetic energy. Electric machine ( 1 ) according to one of the preceding claims, characterized in that the stator ( 3 ) includes a plurality of separately switchable short-circuit windings. Electric machine ( 1 ) according to one of the preceding claims, characterized by magnetic field sensors for detecting the angular positions of the motor rotor ( 9 ) and the further motor rotor ( 11 ). Use of the electric machine ( 1 ) according to one of the preceding claims as a final drive and / or recuperation, in particular a non-actively steered axle, preferably a rear axle, in a land vehicle, in particular a motor vehicle. Method for controlling an electric machine ( 1 ) with the features of claim 12, characterized in that by switching the switching arrangement ( 5 ) depending on the angular positions of the motor rotor ( 9 ) and the further motor rotor ( 11 ) the directions of rotation of the motor rotor ( 9 ) and the further motor rotor ( 11 ) to be controlled. Method according to claim 13, characterized in that the motor rotor ( 9 ) and / or the further motor rotor ( 11 ) along the excellent axis direction ( 5 ) are shifted relative to the at least one short-circuit winding, so that an active conductor length for an interaction with that of the permanent magnet of the motor rotor ( 9 ) Magnetic field and / or further active conductor length of the at least one short-circuit winding for an interaction with that of the other permanent magnets of the further motor rotor ( 11 Magnetic field changed, and this is a speed and torque transmission of the motor rotor ( 9 ) and / or the further motor rotor ( 11 ) to be controlled.