DE102018216881A1 - Method and device for operating an electrical machine and electrical machine - Google Patents

Abstract

The electrical machine comprises a rotor and a torque sensor with a sensor element (6). The sensor element (6) is arranged on the rotor. Furthermore, the electrical machine comprises a field-oriented control or the field-oriented control is assigned to the electrical machine. The electrical machine has a module or the module is assigned to the electrical machine. The module comprises a predetermined machine model and / or a further sensor and is designed to record and / or determine an input variable for the field-oriented control and to make it available for the field-oriented control. A parameter is detected and / or determined by means of the torque sensor, which is representative of an output torque of the rotor, and a parameter of the machine model and / or a detection error of the further sensor is adapted depending on the parameter.

Description

The invention relates to a method and a corresponding device for operating an electrical machine and the electrical machine.

Electrical vehicles are increasingly being used as drive motors in motor vehicles. For efficient operation of the regulated electrical machine, it is advantageous to precisely determine reference variables and to precisely record or determine feedback variables for the regulation.

The object on which the invention is based is to create a method and a corresponding device for operating an electrical machine which enable precise control of the electrical machine and / or more efficient operation of the electrical machine.

The object is achieved by the features of the independent claims. Advantageous developments of the invention are characterized in the subclaims.

According to a first and second aspect, the invention is characterized by a method and a corresponding device for operating an electrical machine. The electrical machine comprises a rotor and a torque sensor with a sensor element. The sensor element is arranged on the rotor, for example on a rotor shaft or a rotor core of the rotor. Furthermore, the electrical machine comprises a field-oriented control or the field-oriented control is assigned to the electrical machine. The electrical machine has a module or the module is assigned to the electrical machine. The module comprises a predetermined machine model and / or a further sensor and is designed to record and / or determine an input variable for the field-oriented control and to make it available for the field-oriented control. A parameter is detected and / or determined by means of the torque sensor, which is representative of an output torque of the rotor, and a parameter of the machine model and / or a detection error of the further sensor is adapted depending on the parameter.

By means of the direct torque measurement, the machine model and / or correction values for the further sensor can be adapted for the highest possible efficiency of the electrical machine over a lifetime of the electrical machine. As a result, an optimal or at least improved utilization is made possible for a drive which comprises the electrical machine, irrespective of tolerances, for example manufacturing tolerances and / or sensor tolerances. The pre-control of the field-oriented control is improved by the adaptation, which leads to a further increase in efficiency of the drive and thus, for example, improves the range of a vehicle which has the electrical machine. In addition, tolerances due to the aging of mechanical components of the machine as well as electrical components such as inverters, half bridges and / or sensors can be adapted over the lifetime of the machine.

There is also a further degree of freedom in the design of the electrical machines. Tolerances can be loosened and cheaper materials can be used. As a result, the electrical machine can be reduced in cost.

In an advantageous embodiment according to the first and second aspects, the module has the machine model and is designed to determine, depending on a predetermined torque for the rotor and the predetermined machine model, desired components of a stator current of the electrical machine that are fed to the field-oriented control as input variables will. Here, the machine model comprises a predetermined map for determining the target components of a stator current for optimized operation of the electric machine with respect to an efficiency and / or an efficiency of the electric machine, and adapting the parameter of the machine model comprises adapting the map.

The specified map is usually determined for a reference machine and then used for identical or similar machines. The map is used to design and calibrate the torque of the electrical machine. Due to the tolerances of the electrical machine and its control, the set torque differs if both machines are operated under the same operating conditions. The adaptation of the characteristic diagram for the electrical machine enables the optimal target components of the stator current for all operating points to be determined quickly and easily by means of the adapted characteristic diagram.

In a further advantageous embodiment according to the first and second aspects, adapting the characteristic diagram comprises determining a control torque for the electrical machine as a function of a requested torque of the electrical machine and the characteristic variable. Furthermore, for the determined control torque, the components of the stator current are optimized as a function of a minimum length of a resulting current vector of the components of the stator current predetermined degrees of modulation of a space-pointer modulation of the field-oriented control. If an operating point is reached at which a predetermined optimization criterion is met, the map for this operating point is adapted in relation to the components of the stator current to be set and / or the degree of modulation and / or the torque.

In a further advantageous embodiment according to the first and second aspects, the module has, as the further sensor, an angular position detection sensor which is designed to detect and / or determine an angular position of the rotor. In this case, the at least one input variable comprises the detected angular position of the rotor, and adapting the detection error of the further sensor comprises adapting an angle of rotation error of the angular position detection sensor.

Through direct torque measurement, the angular position detection sensor can be adapted over the lifetime of the electrical machine.

In a further advantageous embodiment according to the first and second aspects, in order to adapt the angle of rotation error, the electrical machine is operated at a stationary operating point for which a target torque of the rotor is specified. During operation, a current angular position of the rotor is recorded in step (a), and a corrected angular position is determined in step (b) depending on a predetermined adaptation rule. In step (c) the corrected angular position is provided as the input variable for the field-oriented control. Steps (a) to (c) are repeated until a difference between the measured parameter and the predetermined target torque is minimal.

In a further advantageous embodiment according to the first and second aspects, the electrical machine is operated in a field weakening mode, preferably in a field weakening mode without voltage limitation. This has the advantage that a torque deviation in the case of angular errors is larger and less dependent on other error variables. This makes it easier to separate the source of the error.

In a further advantageous embodiment according to the first and second aspects, the electrical machine has a rotational speed in the stationary operating state above a predetermined limit rotational speed. It is advantageous if the machine is operated at the highest possible speed, so that possible cross influences due to tolerances in the magnetic flux, in current sensors, in the rotor temperature and stator inductances play a subordinate role.

In a further advantageous embodiment according to the first and second aspects, the sensor element comprises at least one strain gauge. The strain gauge is preferably designed as a piezoresistive strain gauge. In particular, the sensor element can have four strain gauges.

In a further advantageous embodiment according to the first and second aspects, the rotor has a rotor shaft and the sensor element is arranged on an end face of the rotor shaft of the rotor.

In a further advantageous embodiment according to the first and second aspects, the rotor comprises a rotor shaft and a rotor core. The rotor core has at least two first recesses, which are separated by a web. The sensor element is arranged on one of the webs, which is formed between two adjacent recesses. The rotor can alternatively have a plurality of sensor elements and the respective sensor elements can each be arranged on one of the webs.

In a further advantageous embodiment according to the first and second aspects, the at least two first recesses extend along a longitudinal axis of the rotor core.

In a further advantageous embodiment according to the first and second aspects, the at least two first recesses are arranged symmetrically in the circumferential direction of the rotor core around the rotor shaft. In this way, an unbalance of the electrical machine can advantageously be avoided or at least kept small. Due to the direct arrangement of the at least one sensor element on the rotor, the rotor can be balanced after the at least one sensor element has been applied, so that any imbalance caused by the at least one sensor element can be minimized.

In a further advantageous embodiment according to the first and second aspects, the rotor core has second recesses for the arrangement of permanent magnets or windings and the first recesses are arranged in the radial direction between the first recesses and the rotor shaft. The integration of the magnets has the advantage that the rotor diameter can be reduced. Furthermore, the magnetic flux density of the air gap can be increased by the concentration of the magnetic field, which enables less magnetic control of the electrical machine.

According to a third aspect, the invention is characterized by an electrical machine which has a device according to the second aspect, has a rotor and a torque sensor with a sensor element. The sensor element is arranged on the rotor and the device is coupled to the sensor element in terms of signal technology.

Advantageous embodiments according to the second aspect are also valid for the third aspect.

Exemplary embodiments of the invention are explained below with reference to the schematic drawings.

• 1a eine perspektivische Ansicht eines Ausführungsbeispiels eines Rotors einer elektrischen Maschine,
• 1b eine stirnseitige Aufsicht auf ein weiteres Ausführungsbeispiel eines Rotors einer elektrischen Maschine,
• 2 eine beispielhafte Anordnung eines Sensorelements an einer Rotorwelle,
• 3 ein beispielhaftes Modell für eine feldorientierte Reglung einer elektrischen Maschine,
• 4 ein beispielhaftes Isolinen-Diagramm für ein Drehmoment einer elektrischen Maschine,
• 5 eine beispielhafte Drehmomentkennlinie einer elektrischen Maschine,
• 6 ein Ablaufdiagramm für ein Programm zum Betreiben der elektrischen Maschine und
• 7 ein beispielhaftes Modell für eine erweiterte feldorientierte Reglung der elektrischen Maschine.

Show it:

• 1a 1 shows a perspective view of an exemplary embodiment of a rotor of an electrical machine,
• 1b an end view of another embodiment of a rotor of an electrical machine,
• 2nd an exemplary arrangement of a sensor element on a rotor shaft,
• 3rd an exemplary model for a field-oriented control of an electrical machine,
• 4th an exemplary isoline diagram for a torque of an electrical machine,
• 5 an exemplary torque characteristic of an electrical machine,
• 6 a flowchart for a program for operating the electrical machine and
• 7 an exemplary model for an extended field-oriented control of the electrical machine.

Elements of the same construction or function are provided with the same reference symbols in all figures.

1a shows a perspective view of an embodiment of a rotor of an electrical machine.

The electrical machine is, for example, a permanently excited synchronous machine.

How 1 shows, the rotor comprises a rotor core 1 and a rotor shaft 2nd , with the rotor shaft 2nd inside the rotor core 1 is arranged; in particular is the rotor shaft 2nd firmly in a shaft hole in the rotor core 1 arranged to it the rotor core 1 to allow the rotor shaft 2nd together with the rotor core 1 to turn. The material of the rotor core 1 includes, for example, silicon steel.

As in 1a are shown in the rotor core 1 at least two first recesses 4th arranged by a footbridge 5 are separated. At the in 1 shown embodiment has the rotor core 1 four first recesses 4th on. The first recesses 4th extend along an axial longitudinal direction of the rotor shaft 2nd . The first recesses 4th serve in particular to reduce a rotary mass of the rotor.

The first recesses 4th are, for example, in the circumferential direction of the rotor core 1 symmetrical around the rotor shaft 2nd arranged around.

The respective first recesses are preferred 4th the same or at least very similar in terms of their design. The first recesses 4th can however be designed differently from rotor to rotor.

The rotor core 1 has, for example, second recesses 3rd to arrange permanent magnets or windings. The first recesses 4th are preferably in the radial direction between the second recesses 3rd and the rotor shaft 2nd arranged.

The rotor comprises a torque sensor with at least one sensor element 6 , which is designed to detect and / or determine a measured variable that is representative of a torque of the rotor.
The at least one sensor element 6 is arranged on the rotor. For example, the sensor element 6 on the rotor core 1 arranged.

The sensor element 6 is on the rotor, for example on one of the webs 5 that between two adjacent first recesses 4th is formed, arranged.
The sensor element 6 can be clamped, glued or screwed onto the rotor, for example. The arrangement of the sensor element 6 to the rotor can be done by means of a detachable connection or an undetachable connection.

A torque transmitted via the rotor leads to torsion of the rotor, which occurs in the form of compressive and tensile stresses at an angle of 45 ° to an axial direction of the rotor. The torsion of the rotor leads to a change in the resistance of the strain gauges, which is evaluated, for example, by a suitable voltage measurement on the strain gauges.

1b shows an end view of another embodiment of a rotor of an electrical machine. The rotor comprises a rotor core 1 , a rotor shaft 2nd , first recesses 4th and second recesses 3rd . The rotor shaft 2nd is designed, for example, as a hollow shaft. In contrast to the one in 1a Embodiment shown are in the in 1b Embodiment shown the second recesses 3rd shaped differently. Furthermore, the rotor in 1b four sensor elements 6 on, for example, symmetrically around the rotor shaft 2nd are arranged around to minimize possible imbalances.

The in the 1a and 1b shown sensor elements 6 include, for example, at least one piezoresistive strain gauge.

The torque sensor has one in the 1a and 1b First evaluation electronics, not shown, with the one or more sensor elements 6 is electrically coupled for receiving sensor signals of the sensor element or elements 6 . The first evaluation electronics are arranged, for example, in a bearing shell of the rotor. The first evaluation electronics are, for example, radio-technically coupled to a computing unit, which can also be referred to as a device for operating the electrical machine.

Alternatively, the sensor element 6 on the rotor shaft 2nd of the rotor.

2nd shows an exemplary arrangement of the sensor element 6 on one end of the rotor shaft 2nd . The torque transmitted via the shaft leads to torsion of the rotor, which in the form of compressive and tensile stresses at a 45 ° angle along a longitudinal axis of the rotor shaft 2nd occur. The sensor element 6 is therefore preferably arranged at an angle of 45 ° with respect to the longitudinal axis of the rotor.

The sensor element has at least one strain gauge. The strain gauge is preferably a piezoresistive strain gauge.

The at least one strain gauge is arranged on a silicon chip, for example. The at least one strain gauge is glassed onto the silicon chip, for example. The strain gauges are designed, for example, as a microsystem chip, in the English microelectromechanical system (MEMS) chip.

Alternatively, the sensor element has a plurality of strain gauges which form a resistance network, in particular an ohmic resistance network. For example, the sensor element 5 four piezoresistive strain gauges. The strain gauges are electrically coupled so that they form a measuring bridge.

3rd shows an exemplary model for a field-oriented control of an electrical machine.

The control is designed, for example, as a field-oriented control. The field-oriented control (Field Oriented Control or Vector Control) is designed as a control method for three-phase machines. The aim of this control method for asynchronous machines or synchronous machines is to obtain a decoupled control of magnetic flux and torque in order to simulate a behavior like that of a DC shunt machine.

This in 3rd The model shown applies to a permanently excited synchronous machine.

For example, the model has a PI current controller in the forward direction 20th , a first unit 22 , which is designed to carry out an inverse Clarke transformation and a space vector pulse width modulation, and for example a B6 inverter 24th on. There is a second unit in a feedback loop 26 arranged, which is designed to perform a Clarke Parks transformation. Furthermore, the control loop of the field-oriented control is a first module 28 upstream, which is formed depending on input variables such as speed, magnetic flux and requested torque Treq and a predetermined map of target components Id_s , Iq_s to determine a stator current of the electrical machine, which are fed to the control loop.

The torque of a permanently excited synchronous machine can be calculated using Eq. 1 can be described: $$\text{Tq}=\mathrm{3rd}/\mathrm{2nd}*(\text{Zp}*\left[\Psi *\text{id}+\left(\text{Ld}+\text{Lq}\right)*\text{Id}*\text{Iq}\right]$$

Tq

inneres Drehmoment (elektromagnetisches Drehmoment ohne mechanische Drehmomentverluste)

Iq, Id

Komponenten des Statorstromes im feldorientierten d/q Koordinatensystem

Ψ

Rotorfluss im feldorientierten d/q Koordinatensystem

Ld, Lq

Komponenten der Statorinduktivitäten im feldorientierten d/q Koordinatensystem

Zp

Polpaarzahl

Here denote:

Tq

internal torque (electromagnetic torque without mechanical torque loss)

Iq, Id

Components of the stator current in the field-oriented d / q coordinate system

Ψ

Rotor flux in the field-oriented d / q coordinate system

Ld, Lq

Components of the stator inductances in the field-oriented d / q coordinate system

Zp

Number of pole pairs

The sizes Ψ, Ld and Lq are not exactly known due to manufacturing tolerances and aging of the electrical machine. In addition, the determination of the actual components Iq_i , Id_i of the stator current is tolerant due to the measuring accuracy of shunt or Hall sensors and the tolerance in the rotor position.

The torque output is therefore subject to tolerances which have a negative effect on control accuracy, in particular in the case of hybrid drives, and on the efficiency of the electrical machine.

The target components Id_s , Iq_s of the stator current are determined, for example, using a map. The map maps the inverse of equation (1) given above and uses a requested torque, a speed and a magnetic flux as well as a temperature as input variables. Since tolerances are not taken into account in the map for the machine actually used, efficient operation of the machine is often not guaranteed. In addition, there is no guarantee that the requested torque will also be achieved. Deviations of around 10% between the required and the actual moment are possible.

The tolerances of the electrical machine are currently being minimized by using expensive, high-quality materials, for example for permanent magnets, as well as tight manufacturing tolerances.

Optimal operating parameters for electrical machines are currently mainly determined on the basis of a selected electrical machine. The optimal operating parameters are saved in the form of maps. The characteristic diagrams are then used, for example, for identical electrical machines for a pilot control, as in 3rd shown, used.

4th shows an exemplary diagram with isolines for the torque. An operating range of the electrical machine is limited, on the one hand, by a maximum current which, for example, an inverter matched to the machine can deliver, and a maximum degree of modulation of the space vector pulse width modulation. The optimal operating point is reached when a resulting vector from the components Iq and Id of the stator current reaches a minimum length. In 4th the bold line represents the optimal components Iq and Id of the stator for stationary operating points.

Since the machines are never exactly identical and additional differences between the machines can occur due to a lifetime and / or useful life, the map used by the electric machine must be adapted to pre-control the torque of the electric machine to be output in conjunction with the field-oriented control is used, desirable.

5 shows an exemplary torque characteristic of an electrical machine depending on the speed or speed. The electric machine delivers the highest torque at low engine speeds, but this drops continuously after the highest output is reached.

In a first operating area, which is in 5 with the number 1 is marked and at which the output torque is highest, in particular tolerances of the magnetic flux, the accuracy of a phase current sensor and an inaccuracy of a rotor temperature model lead to torque deviations. In a second operating area, which is in 5 with the number 2nd is marked, tolerances of the magnetic flux, the accuracy of a phase current sensor and an inaccuracy of a rotor temperature model and also tolerances of a rotor position sensor also lead to torque deviations. In a third operating area, which is in 5 with the number 3rd is marked and which is characterized by low torque output at a high speed at the same time, tolerances of a rotor position sensor lead to torque deviations.

The torque output is therefore subject to tolerance. It can be seen that tolerances with respect to a detected and / or determined angular position of the rotor lead to torque errors, particularly at higher speeds.

The direct measurement of the torque delivered to the rotor enables improved torque precontrol and / or increased control accuracy.

6 shows a flowchart for a program for operating the electrical machine, which enables an adaptation of the control, more specifically an adaptation of the pilot control and a feedback loop of the control.

The electrical machine includes a field-oriented control. Alternatively, the field-oriented regulation of the electrical machine can then be assigned. The electrical machine has a module which comprises a predetermined machine model and / or a further sensor and is designed to detect and / or determine an input variable for the field-oriented control and to make it available for the field-oriented control. Alternatively, the electrical machine has the module not on itself, but the module is assigned to the electrical machine.

The program is executed, for example, by the computing unit. The electrical machine includes, for example, the computing unit. Alternatively, the computing unit can be assigned to the electrical machine. The computing unit can also be referred to as a device for operating an electrical machine.

The program is in one step S1 started.

In one step S3 a parameter that is representative of an output torque of the rotor, which is detected and / or determined by means of a torque sensor, is read in.

In one step S5 a parameter of the machine model and / or a detection error of the further sensor is adapted depending on the parameter.

In one step S7 For example, the adapted machine model and / or an adaptation map for the further sensor for field-oriented control of a given interface is provided.

In one step S9 the program is ended. However, continuous adaptation is preferably carried out so that the program is executed repeatedly at predetermined time intervals.

The module has, for example, the machine model and is designed, depending on a predetermined torque for the rotor and the predetermined machine model, target components Id_s , Iq_s to determine a stator current of the electrical machine, which are supplied to the field-oriented control as input variables, the machine model comprising a predetermined characteristic map for determining the target components Id_s , Iq_s a stator current for an optimized operation of the electrical machine in relation to an efficiency and / or an efficiency of the electrical machine.
Adapting the parameter of the machine model here includes adapting the map. In this case, the module corresponds, for example, to that in 3rd and 7 shown first module 28 .

In this case, for example, in the step S5 To adapt the characteristic map, a control torque for the electrical machine is determined as a function of a requested torque of the electrical machine and the parameter.

For example, as in 7 can be seen in 3rd shown field-oriented control initially expanded by a torque control loop.

For example, an output torque of the electrical machine becomes dependent on a mechanical model 32 determined for a rotor bearing of the electrical machine and the detected or determined torque of the rotor. A difference between the determined delivered torque and the requested torque is a PI controller 29 led to.

The torque control loop makes it possible to set an actually requested torque.

In a next step, the components of the stator current are optimized for the control torque with respect to a minimum length of a resulting current vector of the components of the stator current depending on given degrees of modulation of a space-pointer modulation of the field-oriented control.

For this purpose, for example, the components of the stator current are optimized by means of an optimization method, for example a gradient method, a parameter estimation method, a Kalman filtering and / or a model-predictive control, for a given degree of modulation of a space-pointer modulation of the field-oriented control so that the resulting current vector of the components of the stator current has a minimal length. The operating limits of maximum current and maximum voltage / degree of modulation are observed. In a further step, it is checked whether a further reduction in performance can be achieved with a lower degree of modulation. For this purpose, the previous steps are repeated with a lower degree of modulation.

When an operating point is reached at which a predetermined optimization criterion is met, the map for this operating point is adapted in relation to the components of the stator current to be set and / or the degree of modulation and / or the torque. If, for example, the product of current and degree of modulation (voltage) is minimal, the map is adapted for the operating point.

The correct pilot control value (s) is therefore already available for the next change to this operating point. In the map, for example, the target components Id_s , Iq_s of the stator current of the electrical machine as a function of a requested torque, a requested speed and a requested magnetic flux. The target components are adapted Id_s , Iq_s of the stator current as a function of the torque, the speed and the magnetic flux, the magnetic flux being dependent on the degree of modulation and the temperature of the rotor.

Alternatively, the module has an angular position detection sensor, which is designed to detect and / or determine an angular position of the rotor. The at least one input variable comprises the detected angular position of the rotor and the adaptation of the detection error of the further sensor comprises adapting an angle of rotation error of the angular position detection sensor.

In this case, for example, in the step S5 to adapt the angle of rotation error, the electrical machine is operated at a stationary operating point for which a target torque of the rotor is specified.

The electrical machine is preferably operated in a field weakening mode at the highest possible speed. A current angular position of the rotor is recorded and a corrected angular position is determined as a function of a given adaptation rule. The corrected angular position is used as the input variable for field-oriented control. This adaptation of the angular position is repeated until the requested torque, which is detected on the shaft by means of the torque sensor, is established.

For example, the rotor position is gradually adapted using an angular offset.

Without an adaptation of the recorded angular position, deviations in the range from 0 ° to ± 2 ° occur. The adaptation of the detected angular position of the angular position detection sensor enables the detection accuracy to be improved. It is therefore possible to dispense with the use of more precise, and thus more expensive, angular position transmitters.

Reference list

1

Rotor core

2nd

Rotor shaft

3rd

second recess

4th

first recess

5

web

6

Sensor element

20th

PI current controller

22

first unit

24th

B6 inverter

26

second unit

28

first module

29

PI torque controller

32

Mechanical model

Iq_i, Id_i

Actual components of the stator current

Iq_s, Id_s

Target components of the stator current

S1 to S9

Program steps

Claims (15)

Method for operating an electrical machine, in which the electrical machine has a rotor and a torque sensor with a sensor element (6), the sensor element (6) being arranged on the rotor, the electrical machine comprises a field-oriented regulation or the field-oriented regulation is assigned to the electrical machine, - The electrical machine has a module or the module is assigned to the electrical machine, the module comprising a predetermined machine model and / or a further sensor and being designed to detect and / or determine an input variable for the field-oriented control and this for the to provide field-oriented regulation, and the method comprises the following steps: - Providing a parameter that is representative of an output torque of the rotor, which is detected and / or determined by the sensor element (6) and - Adapting a parameter of the machine model and / or a detection error of the further sensor depending on the parameter. Procedure according to Claim 1 , in which - the module has the machine model and is designed to determine target components (Id_s, Iq_s) of a stator current of the electrical machine as a function of a predetermined torque for the rotor and the predetermined machine model, which are fed to the field-oriented control as input variables, wherein the machine model comprises a predetermined characteristic diagram for determining the target components (Id_s, Iq_s) of a stator current for optimized operation of the electrical machine with respect to an efficiency and / or an efficiency of the electrical machine, and - adapting the parameter of the machine model Adapting the map includes. Procedure according to Claim 2 , in which the adaptation of the map comprises the steps: - Determining a control torque for the electrical machine as a function of a requested torque of the electrical machine and the parameter, - Optimizing the components of the stator current with respect to a minimum length of a resulting current vector of the components of the stator current as a function of given degrees of modulation of a space-pointer modulation of the field-oriented Control for the control torque, - when an operating point is reached at which a predetermined optimization criterion is met, the map for this operating point is adjusted in relation to the components of the stator current to be set and / or the degree of modulation and / or the torque. Method according to one of the preceding claims, in which the module has an angular position detection sensor which is designed to detect and / or determine an angular position of the rotor, - The at least one input variable comprises the detected angular position of the rotor, and adapting the detection error of the further sensor comprises adapting an angle of rotation error of the angular position detection sensor. Procedure according to Claim 4 , in which the adaptation of the angle of rotation error comprises the steps: - operating the electrical machine at a stationary operating point for which a target torque of the rotor is specified and during operation (a) detecting a current angular position of the rotor, (b) determining a corrected angular position depending on a given adaptation rule, (c) providing the corrected angular position as the input variable for the field-oriented control, (d) repeating steps (a) to (c) until a difference between the measured parameter and the predetermined target torque is minimal. Procedure according to Claim 5 , in which the electrical machine is operated in a field weakening operation. Procedure according to Claim 5 or 6 , in which the electrical machine has a speed above a predetermined limit speed in the stationary operating state. Method according to one of the preceding claims, wherein the sensor element (6) comprises at least one strain gauge. Method according to one of the preceding claims, in which the sensor element (6) is arranged on an end face of the rotor. Method according to one of the preceding claims, in which - The rotor has a rotor shaft (2) and a rotor core (1), - The rotor core (1) has at least two first recesses (4) which are separated by a web (5) and - The sensor element (6) is arranged on one of the webs (5), which is formed between two adjacent recesses. Procedure according to Claim 10 , in which the at least two first recesses (4) extend along a longitudinal axis of the rotor core (1). Procedure according to Claim 10 or 11 , in which the at least two first recesses (4) are arranged symmetrically around the rotor shaft (2) in the circumferential direction of the rotor core (1). Procedure according to one of the Claims 10 to 12th , in which the rotor core (1) has second recesses (3) for the arrangement of permanent magnets or windings and the first recesses (4) are arranged in the radial direction between the first recesses (4) and the rotor shaft (2). Device for operating an electrical machine which is designed the method according to one of the Claims 1 to 13 to execute. Electrical machine that has a device Claim 14 and has a rotor and a torque sensor with a sensor element (6), the sensor element (6) being arranged on the rotor, and the device being coupled in terms of signal technology to the torque sensor.

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