DE102021124533A1 - Electrical machine, method for controlling an electrical machine, computer program product and control unit - Google Patents

Abstract

The invention relates to an electrical machine (1) comprising a stator (2) and a rotor (3), a motor torque and/or a motor force being transmitted to the rotor (3) via a magnetic field generated by the stator (2). can be introduced, and an adjustment device (4) coupled to the rotor (3) and/or stator (2), the adjustment device (4) being set up to mechanically weaken the magnetic field between the rotor (3) and the stator (2). cause a first motor torque and/or a first motor force on the rotor (3) and/or stator (2) to mechanically put the adjusting device (4) into a first operating state by forming a first imbalance of forces in the adjusting device (4). offset, in which a first magnetic field is formed between the rotor (3) and the stator (2), and a second motor torque and/or a second motor force on the rotor (3) and/or stator (2). Adjusting device (4) mechanically by forming a second imbalance of forces in the adjusting device (4) in a second operating state in which a different from the first magnetic field second magnetic field is formed between the rotor (3) and the stator (2), wherein the electric machine (1) further a control unit ( 5) for controlling the energization of the stator (2).

Description

The present invention relates to an electrical machine comprising a stator and a rotor, a motor torque and/or a motor force being able to be introduced into the rotor via a magnetic field generated by the stator, and an adjustment device coupled to the rotor and/or stator , wherein the adjusting device is set up to mechanically bring about a magnetic field weakening between the rotor and the stator in that a first motor torque and/or a first motor force on the rotor and/or stator mechanically impairs the adjusting device by forming a first force imbalance in the adjusting device is put into a first operating state, in which a first magnetic field is formed between the rotor and the stator, and a second motor torque and/or a second motor force is applied to the rotor and/or stator, the adjusting device mechanically by forming a second Force imbalance in the adjustment in a z offset wide operating state, in which a different from the first magnetic field second magnetic field between the rotor and the stator is formed, wherein the electric machine also has a control unit for controlling the energization of the stator. The invention also relates to a method for controlling an electrical machine, a computer program product and a control unit.

During operation, electrical machines are subject to losses due to reversal of magnetization and eddy currents, which are summarized as iron losses and reduce the machine's efficiency. In mobile applications, particularly when using electric machines within a drive train of a hybrid or all-electric motor vehicle, a low degree of efficiency of the electric machine means a shorter range for the vehicle or an increased need for battery capacity. It is therefore a constant goal, especially in mobile applications with a hybrid or purely electric drive, to minimize the iron losses described.
The so-called permanently excited synchronous machine is an example of such an electrical machine, which can be used within a drive train of a hybrid or fully electrically driven motor vehicle. Due to its high power density compared to other machine types, it is preferably used in the field of electromobility, where the available space is often a limiting factor. The excitation field of the machine is usually generated by permanent magnets that are arranged in the rotor of the machine. A slip ring contact, which is necessary for electrically excited synchronous machines in order to supply current to an excitation coil arranged on the rotor, can be dispensed with in the case of the permanently excited synchronous machine.

However, a disadvantage of permanent excitation is that the excitation field cannot be easily modified. In principle, a synchronous machine can be operated beyond its nominal speed by controlling the so-called field weakening range. In this range, the machine is operated with the maximum rated power, with the torque delivered by the machine being reduced as the speed increases. Electrically excited synchronous machines can be operated very easily in the field weakening range by reducing the excitation current. It is true that possibilities are also known in permanently excited machines of generating an air gap field component via a suitable energization of the stator of the machine, which counteracts the excitation field generated by the permanent magnets and thus weakens it. However, driving the machine in this way causes increased losses, so that the machine can only be operated with reduced efficiency in this area.

Methods for mechanical field weakening are known from the prior art in order to be able to operate permanently excited dynamoelectric machines in the field weakening range without significantly reducing the efficiency of the machine. This is how it shows CN101783536A a permanently excited synchronous motor with buried permanent magnets magnetized in the tangential direction, each of which is followed by a radially displaceable short-circuit block when viewed radially outwards. This short-circuit block is preloaded by a spring in such a way that it is located in a magnetically isolating area of the rotor when the rotor speed is low. As the speed increases, the shorting block is pushed outward against the spring tension, where it forms a shorting path for the magnetic flux. The magnetic leakage flux conducted via this short-circuit path reduces the effective air-gap flux of the machine, so that field-weakening operation is activated.

From the DE 10 2009 038 928 A1 an electric motor with a stator, a rotor and an air gap formed between the stator and the rotor is also known. The size of the air gap is variable as a function of the speed of the electric motor, the air gap being enlarged at higher speeds of the rotor. The air gap is enlarged by axial displacement of the rotor or stator.

From the EP 2 985 893 A1 an electrical axial flow machine with a stator and a rotor is known, the stator comprising at least two stator segments, and the rotor being connected to a rotor shaft, the rotor and/or the rotor shaft being rotatably mounted in a bearing, and the stator segments in Direction of rotation of the rotor are arranged immovably relative to the storage. At least one of the stator segments is movably arranged in the axial or radial direction relative to the bearing in order to adjust the width of the air gap between the rotor and the stator segments.

There is a continuing need for the adjustment of the air gap to be controlled and carried out as specifically as possible at a specific point in time, so that the air gap is adjusted at an optimal operating time and the controller also knows, among other things, the state of the machine (Field strengthened / field weakened). However, this is made more difficult e.g. by friction, hysteresis, as well as manufacturing scatter. This applies in particular if no separate actuator is to be used for the adjustment, but the adjustment is triggered purely by internal forces/torques in the motor. It is the object of the present invention to provide an electrical machine which is improved with regard to the control of a mechanical adjustment device for adjusting the magnetic field between the stator and the rotor. It is also the object of the invention to implement an improved method for controlling an electrical machine.

This object is achieved by an electrical machine comprising a stator and a rotor, a motor torque and/or a motor force being able to be introduced into the rotor via a magnetic field generated by the stator, and a motor torque coupled to the rotor and/or stator Adjusting device, wherein the adjusting device can be actuated in that a first motor torque and/or a first motor force on the rotor and/or stator mechanically puts the adjusting device into a first operating state by forming a first force imbalance in the adjusting device, in which a first magnetic field is formed between the rotor and the stator, and a second motor torque and/or a second motor force on the rotor and/or stator mechanically puts the adjustment device into a second operating state by forming a second force imbalance in the adjustment device, in which a second magnetic field different from the first magnetic field s magnetic field is formed between the rotor and the stator, the electrical machine also having a control unit for controlling the energization of the stator, wherein in order to generate or influence the first imbalance of forces, the stator is supplied by the control device with a first current intensity and a first current angle from a first group of current angles and to generate or influence the second force imbalance, the stator is energized by the control device with a second current level and a second current angle from a second group of current angles, the first current level being different from the second current level and /or the first current angle is different from the second current angle.

According to the invention, a specific motor torque can be achieved by means of different energization of the stator. For example, different combinations of current amplitude and current angle relative to the current rotor position lead to similar torques on the output shaft, with these different combinations causing different axial forces between the rotor and stator. These different combinations of current amplitudes and current angles with the same output torque form a degree of freedom for controlling the motor. This degree of freedom can thus be used for a targeted influencing of the switchover or to support the switchover.

These combinations of current amplitude and current angle are often also referred to as Id/Iq combinations.

It goes without saying that the terms motor torque and motor force are not limited to motor operation of the electrical machine, but also cover generator operation of the electrical machine.

First, the individual elements of the claimed subject matter of the invention are explained in the order in which they are mentioned in the set of claims, and particularly preferred configurations of the subject matter of the invention are described below.

Electrical machines are used to convert electrical energy into mechanical energy and/or vice versa, and generally include a stationary part referred to as a stator, stand or armature and a part referred to as a rotor or runner and arranged movably relative to the stationary part.

The electrical machine can be designed in particular as a rotary machine. The rotary machine can be configured as a radial flux machine or an axial flux machine. A radial flux machine is characterized in that the magnetic field lines in the between rotor and stator formed air gap, extend in the radial direction, while in the case of an axial flow machine, the magnetic field lines extend in the air gap formed between the rotor and stator in the axial direction. In connection with this invention, it is particularly preferred that the electrical machine is configured as an axial flow machine.

Depending on the area of application, it can be advantageous to design an axial flux machine in an I-arrangement or an H-arrangement. In an I arrangement, the rotor is arranged axially next to a stator or between two stators. In an H-arrangement, two rotors are arranged on opposite axial sides of a stator.

In principle, it is also possible for a plurality of rotor-stator configurations to be arranged axially next to one another as an I-type and/or H-type. It would also be possible in this context to arrange both one or more I-type rotor-stator configurations and one or more H-type rotor-stator configurations next to one another in the axial direction. In particular, it is also preferable that the rotor-stator configuration of the H-type and/or the I-type are each configured essentially identically, so that they can be assembled in a modular manner to form an overall configuration. Such rotor-stator configurations can in particular be arranged coaxially to one another and can be connected to a common rotor shaft or to a plurality of rotor shafts.

The electrical machine can preferably have a motor housing. The motor housing can enclose the electric machine. A motor housing can also accommodate the control device, in particular the control and power electronics. The motor housing can also be part of a cooling system for the electric machine and can be designed in such a way that cooling fluid can be supplied to the electric machine via the motor housing and/or the heat can be dissipated to the outside via the housing surfaces. In addition, the motor housing protects the electrical machine and any electronics that may be present from external influences.

A motor housing can be formed in particular from a metallic material. Advantageously, the motor housing can be formed from a cast metal material, such as gray cast iron or cast steel. In principle, it is also conceivable to form the motor housing entirely or partially from a plastic.

The rotor may include a rotor body. In the context of the invention, a rotor body is understood to mean the rotor without a rotor shaft.

The electrical machine also has a control device. A control device, as used in the present invention, is used in particular for the electronic control and/or regulation of one or more technical systems of the electrical machine.

A control device has, in particular, a wired or wireless signal input for receiving electrical signals, in particular, such as sensor signals. Furthermore, a control device likewise preferably has a wired or wireless signal output for the transmission of, in particular, electrical signals, for example to electrical actuators or electrical consumers of the electrically operable axle drive train or of the motor vehicle.

Control operations and/or regulation operations can be carried out within the control device. It is very particularly preferred that the control device includes hardware that is designed to run software. The control device preferably comprises at least one electronic processor for executing program sequences defined in software.

The control device can also have one or more electronic memories in which the data contained in the signals transmitted to the control device can be stored and read out again. Furthermore, the control device can have one or more electronic memories in which data can be stored in a changeable and/or unchangeable manner.

A control device can include a plurality of control devices, which are arranged in particular spatially separated from one another in the motor vehicle. Control units are also referred to as electronic control units (ECU) or electronic control modules (ECM) and preferably have electronic microcontrollers for carrying out computing operations for processing data, particularly preferably using software. The control devices can preferably be networked with one another, so that a wired and/or wireless data exchange between control devices is made possible. In particular, it is also possible to network the control units with one another via bus systems present in the motor vehicle, such as a CAN bus or LIN bus.

The control device very particularly preferably has at least one processor and at least one memory, which in particular contains a computer program code, the memory and the computer program code being configured are, with the processor, causing the control device to execute the computer program code.

The control unit can particularly preferably include a power electronics module for energizing the stator or rotor. A power electronics module is preferably a combination of different components that control or regulate a current to the electrical machine, preferably including peripheral components required for this purpose, such as cooling elements or power supply units. In particular, the power electronics module contains power electronics or one or more power electronics components that are set up to control or regulate a current. This is particularly preferably one or more power switches, e.g. power transistors. The power electronics particularly preferably have more than two, particularly preferably three, phases or current paths which are separate from one another and each have at least one separate power electronics component. The power electronics are preferably designed to control or regulate a power per phase with a peak power, preferably continuous power, of at least 10 W, preferably at least 100 W, particularly preferably at least 1000 W.

An electric machine according to the invention also includes an adjusting device. An adjusting device causes components in the magnetic circuit to be adjusted as a function of the actuating forces acting on it. This adjustment of the components can in particular cause a change in the magnetic flux in the electrical machine. In particular, mechanical mechanisms are also understood as adjustment devices, by means of which an adjustment of the rotor or the rotor body relative to the stator or the stator body is made possible. In the case of axial flow machines, the rotor or the rotor body can be adjusted axially relative to the stator and/or vice versa with the aid of the adjusting device. This achieves a corresponding field weakening or field strengthening of the electrical axial flow machine. The adjusting device preferably does not have an externally powered actuator, such as an electric or hydraulic actuator, for actuating the adjusting device. An adjusting device can be designed as a cam mechanism, for example. In principle, other mechanical mechanisms alone or in combination are also conceivable, for example selected from the group of levers, contours, gears, springs, etc. In particular, one or more springs can be present for setting the force balance and thus for setting the switching points.

The electric machine is intended in particular for use within a drive train of a hybrid or all-electric motor vehicle. In particular, the electrical machine is dimensioned in such a way that vehicle speeds of more than 50 km/h, preferably more than 80 km/h and in particular more than 100 km/h can be achieved. The electric motor particularly preferably has an output of more than 30 kW, preferably more than 50 kW and in particular more than 70 kW. Furthermore, it is preferred that the electrical machine provides speeds greater than 5,000 rpm, particularly preferably greater than 10,000 rpm, very particularly preferably greater than 12,500 rpm.

The electrical machine can also be installed in an electrically operable final drive train. An electric final drive train of a motor vehicle includes an electric machine and a transmission, the electric machine and the transmission forming a structural unit. Provision can in particular be made for the electric machine and the transmission to be arranged in a common drive train housing. Alternatively, it would of course also be possible for the electric machine to have a motor housing and the gearbox to have a gearbox housing, in which case the structural unit can then be effected by fixing the gearbox in relation to the electric machine. This structural unit is sometimes also referred to as the E-axis.

The electrical machine can particularly preferably be provided for use in a hybrid module. In a hybrid module, structural and functional elements of a hybridized drive train can be spatially and/or structurally combined and preconfigured, so that a hybrid module can be integrated in a particularly simple manner into a drive train of a motor vehicle. In particular, an electric motor and a clutch system, in particular with a separating clutch for coupling the electric motor into and/or decoupling the electric motor from the drive train, can be present in a hybrid module.

In an advantageous further development of the invention, it can be provided that in the control device for an operating point of the electrical machine, comprising a speed and/or a torque of the electrical machine, a first group and a second group of pairs of current intensity and current angle are stored, wherein the first group of current intensity current angles comprises at least one pairing of current intensity and current angle, which ver and comprises at least one pair of current strength and current angle, which causes the adjustment device to be transferred from the first operating state to the second operating state, and the second group of current strength-current angles comprises at least one pair of current strength and current angle, which causes the adjustment device to be transferred from the second operating state Prevents operating state in the first operating state and comprises at least one pairing of current and current angle, which causes a transfer of the adjusting device from the second operating state to the first operating state. In this way, field weakening that is simple and reliable in terms of control technology can be effected in particular.

In a further embodiment of the invention, it can also be provided that the adjusting device is configured to mechanically cause a weakening of the magnetic field between the rotor and the stator, an actuation of a clutch and/or an actuation of a brake. In particular, a clutch can also be an eddy current clutch and/or a brake can be an eddy current brake.

According to an advantageous embodiment of the invention, it can be provided that the second current intensity and the second current angle are configured in such a way as to bring about a magnetic field weakening or magnetic field strengthening compared to the first current intensity and the first current angle. The advantage of this configuration is that it allows the electrical machine to be controlled very flexibly and precisely. Furthermore, according to the prior art, field weakening operation for higher speeds is made possible without the magnetic circuit or the permanent magnets being influenced by means of a mechanical adjustment.

According to a further preferred further development of the invention, it can also be provided that the adjustment device is designed to vary the air gap between the stator and rotor, as a result of which mechanically simple and functionally reliable field strengthening or field weakening can be effected.

According to a further particularly preferred embodiment of the invention as an axial flow machine, provision can be made for the first rotor body to be arranged on one axial side of the stator at an axial distance d, forming a first air gap L, and for the axial distance d between the rotor body and the stator can be varied via an adjustment path.

Furthermore, the invention can also be further developed in such a way that the control unit is set up, by setting a predefined current strength and a predefined current angle, which are each applied to the stator, to exert an axial force on the rotor, which is suitable for the axial distance d is varied by the adjusting device. The advantage of this configuration is that the field weakening or field strengthening is caused solely by an adjustable axial force.

1. a) Bestromung des Stators durch die Steuereinrichtung mit einer ersten Stromstärke und einem ersten Stromwinkel zur Erzeugung oder Beeinflussung des ersten Kräfteungleichgewichts,
2. b) Ermittlung des an dem Rotor anliegenden Ist-Betriebspunkts,
3. c) Vergleich des Ist-Betriebspunkts und/oder eines in der Steuereinheit gespeicherten oder ermittelten Soll-Betriebspunkts und/oder eines Kräfteungleichgewichts zwischen dem Rotor und der Verstelleinrichtung mit einem in der Steuereinrichtung gespeicherten oder ermittelten Entscheidungskriterium,
4. d) wobei beim Erfüllen wenigstens eines Entscheidungskriteriums oder mehrerer Entscheidungskriterien von der Steuereinheit eine zweite Stromstärke und ein zweiter Stromwinkel eingestellt wird, so dass eine Aktuierung der Verstelleinrichtung bewirkt ist.

The object of the invention is also achieved by a method for controlling an electrical machine, comprising a stator and a rotor, a motor torque and/or a motor force being able to be introduced into the rotor via a magnetic field generated by the stator, and a adjustment device coupled to the rotor and/or stator, wherein the adjustment device can be actuated in that a first motor torque and/or a first motor force on the rotor and/or stator causes the adjustment device to move mechanically by forming a first imbalance of forces between the rotor and the Adjusting device is placed in a first operating state, in which a first magnetic field is formed between the rotor and the stator, and a second motor torque and/or a second motor force on the rotor and/or stator mechanically changes the adjusting device by forming a second imbalance of forces between the rotor and the adjusting device in a second n operating state, in which a second magnetic field that differs from the first magnetic field is formed between the rotor and the stator, the electric machine also having a control unit for controlling the energization of the stator, comprising the following steps:

1. a) energization of the stator by the control device with a first current intensity and a first current angle to generate or influence the first force imbalance,
2. b) determination of the actual operating point on the rotor,
3. c) comparison of the actual operating point and/or a target operating point stored or determined in the control unit and/or a force imbalance between the rotor and the adjusting device with a decision criterion stored or determined in the control device,
4. d) if at least one decision criterion or several decision criteria are met, a second current intensity and a second current angle are set by the control unit, so that the adjusting device is actuated.

It can also be advantageous to further develop the invention such that the actual operating point and/or the setpoint operating point is defined at least by an engine torque and an engine speed. According to a further preferred embodiment of the subject matter of the invention, it can be provided that the decision criterion includes a multi-dimensional characteristic diagram in which at least one engine torque and one engine speed are present.

In addition to the engine torque and the engine speed, the multi-dimensional characteristic map can include other dimensions such as the electrical efficiency of the electrical machine. As a result, a very precise, map-oriented control or regulation of the electrical machine can be brought about.

The object of the invention is also achieved by a computer program product stored on a machine-readable carrier, or computer data signal embodied by an electromagnetic wave, with a computer program code suitable for carrying out the method according to any one of claims 9-11.

Finally, the object of the invention is also achieved by a control unit for controlling the energization of an electrical machine according to one of claims 1-8, comprising a processor and a memory containing a computer program code, the memory and the computer program code being configured with the processor to cause the control unit to carry out a method according to any one of claims 9-11.

The invention will be explained in more detail below with reference to figures without restricting the general inventive idea.

• 1 eine Axialflussmaschine in einer ersten Betriebsstellung in einer schematischen Axialschnittansicht,
• 2 eine Axialflussmaschine in einer zweiten Betriebsstellung in einer schematischen Axialschnittansicht,
• 3 ein Drehmoment-Stromwinkel-Diagramm und ein Axialkraft-Stromwinkel-Diagramm in einer Gegenüberstellung,
• 4 ein Ablaufdiagramm eines Steuerungsverfahrens, und
• 5 Darstellung des Stromwinkels an schematischen Querschnittsansichten des Stators.

Show it:

• 1 an axial flow machine in a first operating position in a schematic axial sectional view,
• 2 an axial flow machine in a second operating position in a schematic axial sectional view,
• 3 a torque current angle diagram and an axial force current angle diagram in a comparison,
• 4 a flowchart of a control method, and
• 5 Representation of the current angle on schematic cross-sectional views of the stator.

the 1 1 shows an electrical machine 1 configured as an axial flux machine in an H design, comprising a stator 2 and an axially divided rotor 3, which has a common rotor shaft 30 on which the axially spaced rotor bodies 31 are arranged in a rotationally fixed manner. A motor torque and/or a motor force can be introduced into the rotor 3 via a magnetic field generated by the stator 2 . The electrical machine 1 also has an adjustment device 4 coupled to the rotor 3, the adjustment device 4 being set up to mechanically bring about a weakening of the magnetic field between the rotor 3 and the stator 2 by a first motor torque and/or a first motor Force on the rotor 3 and/or stator 2 mechanically puts the adjustment device 4 into a first operating state by forming a first force imbalance in the adjustment device 4, in which a first magnetic field is formed between the rotor 3 and the stator 2. This first operating state is in the 1 shown.

A second motor torque and/or a second motor force that can be applied to the rotor 3 can mechanically put the adjusting device 4 into a second operating state by forming a second force imbalance in the adjusting device 4, in which a second magnetic field that differs from the first magnetic field is formed between the rotor 3 and the stator 2. This operating state is in the 2 shown.

The adjustment device 4 shown is basically known from the prior art, so that the mode of operation is only briefly discussed here. The mechanical adjusting device 4 shown is designed as a cam mechanism in which a rolling body is accommodated axially between two V-shaped raceways and one of the V-shaped raceways is connected to the rotor body 31 and the other V-shaped raceway is non-rotatably connected to the rotor shaft 30. To adjust the adjustment characteristic of the magnetic flux depending on the control variable, counteracting forces (e.g. by means of springs) are integrated or used in the adjusting device 4, which act against the actuating forces and against the magnetic forces between the stator 2 and the rotor 3. Actuating forces, magnetic forces and counter-forces create a balance of forces, which causes a mechanical adjustment of the components in the magnetic flux when the balance changes (e.g. change in speed, change in useful torque). In principle, however, mechanical adjusting devices 4 of any other design are also conceivable.

Depending on the relative torsional angle of the two V-shaped raceways, the V-shaped raceways cause a force-torque translation between the axial force acting on the V-shaped raceways and the transmitted torque, which is applied to the V-shaped raceways . The V-shaped raceways are designed in such a way that different relative torsional angles between the V-shaped raceways occur with different forces or with different torque ratios. The axial force between the rotor 3 and the stator 2 due to the magnetic forces, the counter springs, which act against the magnetic forces, and the axial force from the cam mechanism are in balance.

A change in engine torque and thus in the torque transmitted between the V-shaped raceways causes a change in the axial force due to the translation of the cam mechanism. This change in turn causes the V-shaped raceways to twist against each other until a new equilibrium is established. The twisting of the V-shaped raceways causes the axial distance between the rotor disks 3 and the stator 2 to be adjusted 1 With 2 visible, in which the magnetic air gap is changed.
Optional mechanical end stops that limit the movements (eg towards the end of the V-shaped tracks) are not shown.

The axial flow machine 1 also has a control unit 5 for controlling the energization of the stator 2, with the control device 5 energizing the stator 2 with a first current intensity 21a and a first current angle 22a to generate the first force imbalance, and the stator to generate the second force imbalance 2 is energized by the control device 5 with a second current intensity 21b and a second current angle 212, the first current intensity 21a differing from the second current intensity 21b and/or the first current angle 22a differing from the second current angle 22b.

From the synopsis of 1-2 It can be seen that the second current level 21b and the second current angle 22b are configured to cause a magnetic field weakening or magnetic field strengthening compared to the first current level 21a and the first current angle 22a. The adjusting device 4 is designed to vary the air gap between the stator 2 and the rotor 3 in order to produce the weakening or strengthening of the magnetic field. The first rotor body 31 is arranged on one axial side of the stator 2 at an axial distance d1, forming a first air gap L1, the axial distance d1 between the rotor body 31 and the stator 2 being variable over an adjustment path by means of the adjusting device 4. In the 1-2 an adjustment device 4 is formed on each of the axially spaced rotor bodies 31 .

In principle, it would of course also be conceivable for only one of the rotor bodies 31 to have an adjusting device 4 .

The control unit 5 is set up by setting a predefined current intensity 21 and a predefined current angle 22, which
each applied to the stator 2 to exert an axial force 6 on the rotor 3, which is suitable that the axial distance d1 through the
Adjusting device 4 is varied. This is explained in more detail below.

3 shows in the upper diagram an example of the useful torque generated by two different current amplitudes as a function of the current angle to the rotor position. It can be seen that, for example, a torque of 200 N*m can be achieved both with full current and a current angle of approx. 160° and with half the current and a current angle of approx. 135°. With other current intensities, correspondingly more angles would result.

The lower diagram of the 3 shows an example of the magnetic axial force between the rotor 3 and the stator 2 as a function of the current angle for two different current intensities. It can be seen that, for example, with full current and an angle of 160° (according to the previous example), an axial force of 2500 N results, while with an angle of 135° and half current strength, an axial force of approx. 5,500 N results.

The current angle is based on the 5 explained in more detail. The stator 2 has a stator current component Id and a stator current component Iq in the dq system. The stator current component Id is sometimes referred to as the magnetizing current or no-load current and the stator current component Iq as the torque-forming component. Iq and Id are partial components of the stator current, which were transferred to the rotor reference frame by a park transformation of the stator currents. The Iq component is in phase with the generated stator voltage and creates a magnetic flux centered on the space between the permanent magnet field poles. Id creates a magnetic flux centered on the poles of the permanent magnet. In other words, a fictitious d (direct) winding is aligned with the rotor field, the fictitious q (quadrature) winding is perpendicular to it; they carry the currents Id and Iq. The currents Id and Iq result in a magnetic field direction in the stator 2 without superimposition of the motor magnetic field, as shown in FIG 5 is shown. The current angle results from the angle difference of the magnetic field direction in rotor 3 without superimposition of the stator magnetic field and this magnetic field direction in stator 2.

By now using suitable Id/Iq combinations or combinations of current intensity and current angle to influence the axial force between the rotor 3 and the stator 2 in a targeted manner, the balance of forces of the adjusting device 4 can be influenced in a targeted manner. A change in the balance of forces causes a change in the balance that occurs in the V-shaped raceways and thus a targeted influence on the mechanical field weakening.

This then also results in a method for controlling an electrical machine 1, as from 1-2 is known. The method comprises the following steps and is shown schematically in 4 shown.

In a first method step a), the stator 2 is initially energized by the control device 5 with a first current intensity 21a and a first current angle 22a to form the first imbalance of forces on the adjustment device 4.

The actual operating point present at the rotor 3 is then determined in method step b). The determination can be made by measuring, calculating or estimating one or more parameters characterizing the actual operating point. In particular, the current engine torque and the current engine speed are determined at an actual operating point.

In the subsequent method step d), the actual operating point and/or a target operating point stored or determined in the control unit 5 and/or a force balance between the rotor 3 and the adjustment device 4 are compared with a decision criterion stored or determined in the control device 5 7 is carried out, with the fulfillment of at least one decision criterion 7 or several decision criteria 7 by the control unit 5 in method step d), a second current intensity 21b and a second current angle 22b are set, so that a field weakening or field strengthening of the magnetic field between the rotor 3 and the stator 2 is effected.

The actual operating point and/or the target operating point are defined at least by an engine torque and an engine speed. It can be seen from the 4 Furthermore, that the decision criterion 7 includes a multi-dimensional characteristics map, in which at least one engine torque and one engine speed are present. In the example shown, the multi-dimensional characteristic map also has the electrical efficiency μ as a further dimension. This enables a very precise and reliable map-oriented control of the mechanical field weakening.

In particular, it is also possible for a first group 23 and a second group 24 of current strength/current angle pairings to be stored in the control device 5 for an operating point of the electric machine 1 that is mapped in the characteristics map. The first group 23 of current strength-current angles comprises at least one pair of current strength 21a and current angle 22a, which prevents the adjustment device 4 from being transferred from the first operating state to the second operating state, and at least one pair of current strength 21a and current angle 22a, which prevents the adjustment device from being transferred 4 causes from the first operating state to the second operating state. The second group 23 of current strength/current angles comprises at least one pair of current strength 21b and current angle 22b, which prevents the adjustment device 4 from being transferred from the second operating state to the first operating state, and at least one pair of current strength 21a and current angle 22a, which prevents the adjustment device from being transferred 4 causes from the second operating state to the first operating state.

Of course, it is also possible to carry out the method described in reverse, that is to say the other way around, so that the operating state generated with method step d) can be converted back into the operating state of the electrical machine 1 present in method step a).

The method can in particular be embodied as a computer program product that is stored on a machine-readable carrier, or a computer data signal, embodied by an electromagnetic wave, with a computer program code that is suitable for carrying out the above method. The computer program product can in particular be provided on a server connected to the Internet. In this context, it is particularly preferred that the computer program product is intended to be loaded from a server connected to the Internet into a control unit 5 for controlling the energization of an electrical machine 1 .

The control unit 5 for controlling the energization of an electrical machine 1, as in the 1-2 shown comprises a processor 51 and a memory 52 containing computer program code, the memory 52 and the computer program code are configured with the processor 51, the control unit 5 to carry out the from the 4 known procedure.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered as limiting but as illustrative. The following patent claims are to be understood in such a way that a mentioned feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' feature, this designation serves to distinguish between two similar features without establishing a ranking.

Reference List

1

electric machine

2

stator

3

rotor

4

adjusting device

5

control unit

6

power

7

decision criterion

21

amperage

22

current angle

23

first group

24

second group

30

rotor shaft

31

rotor body

51

processor

52

Storage

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• CN 101783536A [0004]
• DE 102009038928 A1 [0005]
• EP 2985893 A1 [0006]

Claims (13)

Electrical machine (1) comprising a stator (2) and a rotor (3), a motor torque and/or a motor force being able to be introduced into the rotor (3) via a magnetic field generated by the stator (2), and an adjustment device (4) coupled to the rotor (3) and/or stator (2), wherein the adjustment device (4) can be actuated by applying a first motor torque and/or a first motor force to the rotor (3) and /or the stator (2) mechanically puts the adjusting device (4) into a first operating state by forming a first force imbalance in the adjusting device (4), in which a first magnetic field is formed between the rotor (3) and the stator (2), and a second motor torque and/or a second motor force on the rotor (3) and/or stator (2) mechanically puts the adjusting device (4) into a second operating state by forming a second imbalance of forces in the adjusting device (4). which one of that first magnetic field different second magnetic field between the rotor (3) and the stator (2) is formed, wherein the electric machine (1) also has a control unit (5) for controlling the energization of the stator (2), characterized in that for generating or influencing the first imbalance of forces the stator (2) is supplied with current by the control device (5) with a first current intensity (21a) and a first current angle (22a) from a first group (23) of current intensity current angles and for generating or influencing the second When there is an imbalance of forces, the control device (5) supplies the stator (2) with a second current intensity (21b) and a second current angle (212) from a second group (24) of current intensity current angles, the first current intensity (21a) being dependent on the second Current intensity (21b) is different and/or the first current angle (22a) is different from the second current angle (22b). Electrical machine (1) according to claim 1 , characterized in that in the control device (5) for an operating point of the electric machine (1), comprising a speed and / or a torque of the electric machine (1), a first group (23) and a second group (24) of Current strength-current angle pairings are stored, the first group (23) of current strength-current angles comprising at least one pairing of current strength (21a) and current angle (22a), which transfer the adjusting device (4) from the first operating state to the second operating state and at least one pairing of current intensity (21a) and current angle (22a), which causes the adjusting device (4) to be transferred from the first operating state to the second operating state, and the second group (23) of current intensity-current angles comprises at least one pairing of current intensity (21b) and current angle (22b) comprises a transfer of the adjusting device (4) from the second operating state to the first operating z state prevented and at least one pairing of current intensity (21a) and current angle (22a), which causes a transfer of the adjusting device (4) from the second operating state to the first operating state. Electrical machine (1) according to claim 1 or 2 , characterized in that the adjusting device (4) is configured to mechanically effect a magnetic field weakening between the rotor (3) and the stator (2), an actuation of a clutch and/or an actuation of a brake. Electrical machine (1) according to one of the preceding claims, characterized in that the second current intensity (21b) and the second current angle (22b) are configured in such a way that a magnetic field weakening compared to the first current intensity (21a) and the first current angle (22a) or to cause magnetic field reinforcement. Electrical machine (1) according to one of the preceding claims, characterized in that the adjusting device (4) is designed to vary the air gap between the stator (2) and rotor (3). Electrical machine (1) according to one of the preceding claims, characterized in that the electrical machine (1) is an axial flow machine. Electrical machine (1) according to one of the preceding claims, characterized in that the first rotor body (31) is arranged on one axial side of the stator (2) at an axial distance (d1), forming a first air gap (L1), and the axial distance (d1) between the rotor body (31) and the stator (2) can be varied over an adjustment path by means of the adjusting device (4). Electrical machine (1) according to one of the preceding claims, characterized in that the control unit (5) is set up by setting a predefined current (21) and a predefined current angle (22), which are each applied to the stator (2), a to exert an axial force (6) on the rotor (3), which is suitable for the axial distance (d1) to be varied by the adjusting device (4). Method for controlling an electrical machine (1), comprising a stator (2) and a rotor (3), with a motor torque and/or a motor force being able to be introduced into the rotor (3) via a magnetic field generated by the stator (2), and a motor connected to the rotor (3) and/or stator ( 2) coupled adjusting device (4), wherein the adjusting device (4) can be actuated by mechanically applying a first motor torque and/or a first motor force to the rotor (3) and/or stator (2). caused by the formation of a first imbalance of forces in the adjusting device (4) in a first operating state in which a first magnetic field is formed between the rotor (3) and the stator (2), and a second motor torque and/or a second motor torque Force on the rotor (3) and/or stator (2) mechanically puts the adjusting device (4) into a second operating state by forming a second imbalance of forces in the adjusting device (4), in which a second magnetic field that differs from the first magnetic field between between the rotor (3) and the stator (2), the electrical machine (1) also having a control unit (5) for controlling the energization of the stator (2), comprising the following steps: a) energizing the stator ( 2) by the control device (5) with a first current intensity (21a) and a first current angle (22a) to generate or influence the first force imbalance, b) determination of the actual operating point applied to the rotor (3), c) comparison of the actual - operating point and/or a target operating point stored or determined in the control unit (5) and/or a force imbalance between the rotor (3) and the adjusting device (4) with a decision criterion (7) stored or determined in the control device (5) , d) a second current intensity (21b) and a second current angle (22b) being set by the control unit (5) when at least one decision criterion (7) or a plurality of decision criteria (7) is met is ellt, so that an actuation of the adjusting device (4) is effected. procedure after claim 9 , characterized in that the actual operating point and / or the target operating point is defined at least by an engine torque and an engine speed. procedure after claim 9 or 10 , characterized in that the decision criterion (7) comprises a multi-dimensional characteristics map, in which at least one engine torque and one engine speed are present. Computer program product stored on a machine-readable carrier, or computer data signal, embodied by an electromagnetic wave, with a computer program code that is suitable for performing the method according to one of claims 9 - 11 . Control unit (5) for controlling the energization of an electrical machine (1) according to one of Claims 1 - 8th , comprising a processor (51) and a memory (52) containing a computer program code, wherein the memory (52) and the computer program code are configured with the processor (51), the control unit (5) for carrying out a method according to one of claims 9 - 11 to cause.

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