DE102018212444B3 - Method and device for checking a rotor position angle - Google Patents

Abstract

The invention relates to a method for checking a rotor position angle (33), wherein a rotor position angle sensor (33) detects the rotor position angle (33) of a rotor of an electric machine (21) operated by means of a three-phase field, and wherein the electric machine (21) 20) is controlled by a vector control and for this purpose at least the detected rotor position angle (33) of the control device (20) is evaluated, comprising the following steps: (a) increasing a d-current (30) by means of a controller (2), (b ) Detecting the rotor position angle (33) by means of the rotor position angle sensor (32), (c) comparing the detected rotor position angle (33) with an expected rotor position angle (34) by means of a comparison device (4), (d) evaluating the detected rotor position angle (33) and / or the rotor position angle sensor (32) based on the comparison result by means of an evaluation device (5), (e) outputting the determined evaluation as evaluation ignal (7) by means of an output device (6). Furthermore, the invention relates to an associated device (1) and an associated steering system.

Description

The invention relates to a method and a device for checking a rotor position angle. In particular, the invention relates to a method and a device for checking a rotor position angle of a rotor of an electric machine in a steering system of a vehicle.

Modern steering systems in vehicles, in particular motor vehicles, have an electrically driven steering assistance, in which a driver of the vehicle is assisted by a steering assistance torque applied by an electric machine. Also in automated driving steering systems are used, in which a transverse guide is completely taken over by an electric machine.

To ensure reliability, these steering systems are designed redundantly in the form of multiple strands. Each strand here comprises an electric machine for providing a support torque during steering, a control device for regulating the electric machine or the assist torque and a rotor position angle sensor which detects a rotor position angle of a rotor of the electric machine and transmits it to the control device. Based on the detected rotor position angle, the control device controls the electric machine, in particular by a vector control.

In multi-stranded steering systems, it may happen that the detected rotor position angles differ from each other. However, it is usually not possible to determine which of the rotor angle sensors is faulty. Through the use of three rotor position sensors, attempts have been made to plausibilize the detected rotor position angles on the basis of a majority decision. In the event of a deviation of the detected rotor position angle of one of the three rotor position sensors from the detected rotor position angles of the other two rotor position sensors, the rotor position angle can still be plausibility checked and provided via the two correctly detected rotor position angles, wherein the rotor position angle detected by the faulty rotor position sensor is then discarded. On the other hand, if the steering system is double-stranded, i. it only has two rotor position sensors, such a plausibility check on a majority decision is not possible.

From the DE 10 2014 102 711 A1 For example, a steering assist system for a steering device of a vehicle is known, wherein the steering assist system comprises a plurality of steering angle sensors.

From the DE 10 2013 212 410 A1 For example, a method for checking a rotation angle of a rotor device to a stator device of an AC electric machine is known. The electrical mesh has a plurality of winding strands, wherein a control device is provided for determining phase currents in the winding strands and / or phase voltages between the winding strands. The method comprises the steps of determining at least one of the phase currents and / or at least one of the phase voltages, determining at least one deviation between the determined phase current and a nominal phase current corresponding thereto and / or between the determined phase voltage and a corresponding desired phase voltage, and detecting an angle error if one of the deviations is outside a tolerance range.

From the DE 10 2005 045 835 A1 For example, a control system for a synchronous motor is known, comprising a rotor consisting of a number of rotor poles, and a stator consisting of a number of stator poles, and having at least one phase winding in connection with at least one stator pole and at least one regulator for supplying a A current command signal consisting of an instruction signal for a longitudinal axis current aligned with the longitudinal axis of the rotor and an instruction signal for a transverse axis current aligned with the transverse axis of the rotor and a control means coupled to the synchronous motor a modulated current signal representing a function of the controlled longitudinal axis current signal and the controlled transverse axis current signal, to the phase winding of the stator to rotate the rotor, and having a rotor position sensor for detecting an actual rotational angle of the rotor. In order to provide a control system for a synchronous motor, which operates with a very precisely balanced rotor angle, it is provided that a high longitudinal axis current is temporarily regulated by the controller and / or the control means, wherein the rotor assumes a predetermined angle of rotation and the predetermined angle of rotation with the Actual rotor angle is compared.

From the DE 10 2008 021 425 A1 For example, a method of aligning a resolver is known, wherein the resolver is for determining a rotor position in an electric motor with respect to a d-axis, the method comprising the steps of: commanding a d-axis current command and a velocity command; Operating the electric motor without a load in response to the d-axis current command and the velocity command; Determining a rotor speed in response to the speed command; and determining an offset of the resolver based on the Speed command and the rotor speed when the rotor speed has stabilized substantially.

From the DE 10 2015 218 141 A1 a device for calibrating an electronically commutated electric machine is known. The machine has a stator and a particular permanent magnetic rotor formed. The electric machine also has a control unit, wherein the control unit is designed to energize the stator, in particular stator coils of the stator, for generating a magnetic rotary field. The machine has a rotor position sensor connected on the input side to the control unit, which is designed to generate a rotor position signal representing a rotor position of the rotor. The control unit is preferably designed to control the stator as a function of the rotor position signal. The control unit of the machine is designed to control the stator in such a torque-release-free manner that only electrical power can be generated in the stator. The device is designed to generate a rotor offset signal representative of a rotor offset as a function of a rotational speed representing the rotor speed and to send this to the control unit.

The invention is based on the object to provide a method and an apparatus for checking a rotor position angle and an associated steering system, in which a faulty rotor position angle and / or a faulty rotor position sensor can be checked improved.

The technical problem is solved by a method with the features of claim 1, a device with the features of claim 6 and a steering system with the features of claim 7. Advantageous embodiments of the invention will become apparent from the dependent claims.

1. (a) Erhöhen eines d-Stroms mittels einer Steuerung,
2. (b) Erfassen des Rotorlagewinkels mittels des Rotorlagewinkelsensors,
3. (c) Vergleichen des erfassten Rotorlagewinkels mit einem erwarteten Rotorlagewinkel mittels einer Vergleichseinrichtung,
4. (d) Bewerten des erfassten Rotorlagewinkels und/oder des Rotorlagewinkelsensors auf Grundlage des Vergleichsergebnisses mittels einer Bewertungseinrichtung,
5. (e) Ausgeben der festgestellten Bewertung als Bewertungssignal mittels einer Ausgabeeinrichtung.

In particular, a method for checking a rotor position angle is provided, wherein a rotor position angle sensor detects the rotor position angle of a rotor of an electric machine operated by means of a three-phase field, and wherein the electric machine is controlled by a control device by a vector control and for this purpose at least the detected rotor position angle of the control device is evaluated, comprising the following steps:

1. (a) increasing a d-current by means of a controller,
2. (b) detecting the rotor position angle by means of the rotor position angle sensor,
3. (c) comparing the detected rotor position angle with an expected rotor position angle by means of a comparison device,
4. (d) evaluating the detected rotor position angle and / or the rotor position angle sensor on the basis of the comparison result by means of an evaluation device,
5. (e) outputting the determined evaluation as an evaluation signal by means of an output device.

Furthermore, a device for checking a rotor position angle is provided, wherein a rotor position angle sensor detects the rotor position angle of a rotor of an electric machine operated by means of a three-phase field, and wherein the electric machine is controlled by a control device by a vector control and for this purpose at least the detected rotor position angle is evaluated by the control device comprising a controller, wherein the controller comprises an input device, a comparison device, an evaluation device and an output device. The controller is configured to cause an increase in d-current. The input device is designed to receive a rotor position angle detected after the increase of the d-current from the rotor position angle sensor. The comparison device is designed to compare the detected rotor position angle with an expected rotor position angle and wherein the evaluation device is designed to evaluate the detected rotor position angle and / or the rotor position angle sensor on the basis of the comparison result. Finally, the output device is designed to output the determined evaluation as evaluation signal.

It is a basic idea of the invention to identify a faulty rotor position angle or an incorrectly operating rotor position angle sensor by increasing a d-current component in the phases of the three-phase current field provided for operating the vector-controlled electric machine. The electric machine should in particular be a phase synchronous motor (phase synchronous motor, PSM). The basic idea is based on the finding that increasing the d-current only increases reactive power when the correct rotor position angle is available to the control device during vector control. Increasing the reactive power does not result in a change in the expected rotor position angle at correctly detected rotor position angle. On the other hand, if the rotor position angle detected and used by the control device as a starting point for the vector control does not correspond to the correct rotor position angle, then not only a reactive power is increased, but also an active power, since the control device in the vector control of a faulty rotor position angle goes out. Since the electric machine reacts to increasing the active power with a changed torque, the rotor position angle shifts so that the rotor position angle detected after increasing the d-current does not coincide with the rotor position angle expected by the control based on the incorrect rotor position angle within the vector control deviates from this. On the basis of a comparison between the rotor position angle detected after increasing the d-current and the rotor position angle expected by the controller in the context of the vector control, the detected rotor position angle or the rotor position angle sensor can be evaluated with regard to their reliability.

The advantage of the invention is that a detected rotor position angle or a rotor position angle sensor can be checked for its quality without the need for additional sensors. The method and the device therefore provide a cost-saving possibility to check the detected rotor position angle.

It can be provided that the method is not carried out by means of a separate device from the control device, but is integrated into the control device and is performed by the control device itself.

According to the invention, the method is additionally carried out for a rotor position angle detected by at least one further rotor position angle sensor. This makes it possible, in particular, to compare a plurality of rotor position angles or a plurality of rotor position angle sensors with one another. The device is designed accordingly, i. E. In particular, it may comprise another control with the same function as the controller. However, it may also be provided that only a single control is provided and this is successively switched to the various rotor position sensors to check them.

According to the invention, it is further provided that the rotor position angle sensor and the at least one further rotor position angle sensor are arranged in different electrical lines of a steering system, wherein each of the electrical lines next to the rotor position sensor each having an electric machine and a respective control device. This makes it possible to carry out the method, for example, in redundantly designed steering systems, wherein the method is carried out separately for each of the strands. Correspondingly, associated parts of the device are associated with the respective strands.

According to the invention, it is further provided that steps (a) to (e) for the rotor position angle sensor and the at least one further rotor position angle sensor are only performed if a difference between a detected rotor position angle of the rotor position sensor and a detected rotor position angle of the at least one further rotor position angle sensor reaches a threshold value or exceeds. In this way, resources can be saved and unnecessary intervention in the vector control can be avoided since the d-current is increased only when a difference between the rotor position angles detected by the different rotor position sensors reaches or exceeds the threshold value. Normally, the procedure is then not carried out and resources can be saved. The threshold may be, for example, a difference of at least 5 degrees. The device is designed accordingly. The device comprises an activation device which is designed to compare the rotor position angles detected by the plurality of rotor position angle sensors with one another and to activate the controls only when there is a difference which reaches or exceeds the threshold value.

In one embodiment, it is provided that a difference angle is determined from the detected rotor position angle and the expected rotor position angle for the evaluation, wherein the detected rotor position angle and / or the rotor position sensor are assessed as faulty when the difference angle reaches or exceeds a threshold value. In the apparatus, it is accordingly provided that the controller is further configured to determine a difference angle from the detected rotor position angle and the expected rotor position angle and to evaluate the detected rotor position angle and / or the rotor position angle sensor as defective if the difference angle reaches a threshold value or exceeds. The difference can be formed, for example, by the comparison device.

In particular, it can be provided that the electrical machines of at least two strands are physically designed as a single electric machine or a motor with at least two winding strands. In this case, a shared rotor can be driven both by means of a current induced in one winding strand and by means of a current induced in the other winding strand. The windings may also be operated in combination with one another. Such a combined electric machine is used in steering systems to increase reliability. Each part is controlled by means of its own control device, wherein these relate to a rotor position angle each of a separate rotor position sensor.

In a further embodiment, it is provided that it is decided on the basis of the determined assessments, which of the electrical strands of the steering system is switched off or continued to operate. For example, if two electrical strands present in the steering system and it is found that the rotor position angle or the rotor position sensor of the one electrical strand is faulty, so this electrical strand can be switched off and the steering system can be operated exclusively with the help of the other electrical strand. Since a third rotor position sensor is not needed, this saves costs, but still increases the reliability of the steering system. Accordingly, the device comprises a decision device, which is designed to decide on the basis of the determined evaluations which of the electrical strands of the steering system is switched off or continues to operate and to output a corresponding decision signal.

In a further embodiment, it is provided that an error message is output when at least one of the electrical strands of the steering system is or was turned off. As a result, the driver of the vehicle is informed that the steering system has been partially switched off and, for example, a workshop visit should be scheduled. In the device is provided accordingly, that the controls are further configured to issue an error message when at least one of the electrical strands of the steering system is turned off or was.

In one embodiment, it is provided that a rotor position angle rated as faulty is replaced by a rotor position angle which is not detected as being faulty and has been detected by another rotor position angle sensor, for which purpose the rotor position angle which has not been assessed as faulty is transmitted to the corresponding control device. In this way, an electrical train of the steering system, the rotor position sensor is defective, still be operated based on the transmitted from a rotor position sensor of another electrical strand rotor position angle. It is accordingly provided in the device that the controls are further configured to replace a rotor attitude angle rated as faulty by a rotor attitude angle not detected as faulty detected by another rotor attitude sensor and, for this, the rotor attitude angle not judged to be faulty to the corresponding control equipment to convey.

Parts of the device may be formed individually or in a group as a combination of hardware and software, for example as program code executed on a microcontroller or microprocessor.

• 1 eine schematische Darstellung einer Regelungseinrichtung zum Regeln einer elektrischen Maschine durch Vektorregelung aus dem Stand der Technik;
• 2 eine schematische Darstellung einer Ausführungsform der Vorrichtung zum Überprüfen eines Rotorlagewinkels;
• 3 eine schematische Darstellung einer weiteren Ausführungsform der Vorrichtung zum Überprüfen eines Rotorlagewinkels für ein Lenkungssystem mit zwei elektrischen Strängen;
• 4 ein schematisches Ablaufdiagramm einer Ausführungsform des Verfahrens zum Überprüfen eines Rotorlagewinkels.

The invention will be explained in more detail with reference to preferred embodiments with reference to the figures. Hereby show:

• 1 a schematic representation of a control device for controlling an electric machine by vector control of the prior art;
• 2 a schematic representation of an embodiment of the device for checking a rotor position angle;
• 3 a schematic representation of another embodiment of the device for checking a rotor position angle for a steering system with two electrical strands;
• 4 a schematic flow diagram of an embodiment of the method for checking a rotor position angle.

1 shows a schematic representation of a typical control device 20 for controlling an electric machine 21 by way of vector control (dq system) from the prior art. The goal is the electric machine 21 to drive by means of a three-phase field, for which purpose a direct current or a DC voltage 22 in three phases 23 of the three-phase field by means of a three-phase four-quadrant 24 (English H-Bridge) is converted. Based on a PI regulation 28 become the drive signals 27 for the three-phase four-quadrant plate 24 through an inverse Clarke transformation 25 and a subsequent space vector modulation 26 educated. The PI control 28 uses as reference values a given q-current 29 and a given d-current 30 , The feedback in the PI control 28 is based on the three phase currents 23 , which by means of a Clarke Parks transformation 31 be transformed into the qd system. The inverse Clarke transformation 25 and the Clarke Parks Transformation 31 are based on a means of a rotor position sensor 32 detected rotor position angle 33 ,

In 2 is a schematic representation of a non-inventive embodiment of the device 1 for checking a rotor position angle 33 shown. The device 1 includes a controller 2 , The control 2 has an input device 3 , a comparison device 4 , an evaluation facility 5 and an output device 6 on.

For checking the rotor position angle 33 increases the control 2 a d-current 30 , which is the reference value for the vector control of a control device 20 (see. 1 ) is given. Subsequently, the input device receives 3 a detected after increasing the d-current rotor position angle 33 from the rotor position angle sensor 32 , This can be done indirectly via the control device 20 done so that the detected rotor position angle 33 the input device 3 from the control device 20 provided.

The comparison device 4 compares the received detected rotor attitude angle 33 with an expected rotor attitude angle 34 , The expected rotor position angle 34 becomes the comparator 4 for example, also from the control device 20 made available. The expected rotor position angle 34 corresponds to the rotor position angle, the control device 20 estimated at the time and in the transformations (cf. 2 ), to which the rotor attitude angle 33 was detected after increasing the d-current 30.

The comparing may be forming a difference between the detected rotor attitude angle 33 and the expected rotor attitude angle 34 include.

Performs increasing d-current 30 only to an increase of the reactive power, that is, the rotor position sensor works 32 correct, the detected rotor position angle 33 and the expected rotor attitude angle 34 agree with each other. Works the rotor angle sensor 32 on the other hand, not correct and provides a faulty rotor position angle 33 to the control device 20 , so increasing the d-current 30 also leads to an increase in the active power, so that the rotor of the electric machine 21 an additional torque is generated, resulting in a change in the rotor position angle 33 leads. The expected rotor position angle 34 and the detected rotor attitude angle 33 then deviate from each other.

The evaluation facility 5 evaluates the detected rotor position angle 33 and / or the rotor position angle sensor 34 then based on the comparison result of the comparison device 4 ,

It can be provided here that the detected rotor position angle 33 is assessed as faulty if one of the detected rotor position angle 33 and the expected rotor attitude angle 34 formed difference exceeds a predetermined threshold, for example, if a deviation is greater than 5 degrees.

The output device 6 then gives the established rating as a rating signal 7 out. The evaluation signal 7 For example, it can be forwarded to a steering system and further processed by it.

In 3 is a schematic representation of an embodiment of the device according to the invention 1 for checking a rotor position angle 33 . 53 for a steering system with two electrical strings 60 . 61 shown. Each of the strands 60 . 61 each includes a control device 20 . 40 and one electric machine each 21 . 41 each with a rotor position sensor 32 . 52 , It can be provided here that the electrical machines 21 . 41 physically as a single engine 63 are formed, ie that the electrical machines 21 . 41 each individual winding strands of this motor 63 represent and share a rotor together.

The device 1 is the same as the one in 2 shown device 1 but additionally includes one for control 2 identically formed further control 12 with another input device 13 , another comparison device 14 , another evaluation facility 15 and another output device 16 , The further control 12 works analogous to the controller 2 , As the electrical machines 21 . 41 are coupled to each other via the common rotor, is to check the respective rotor position angle 33 . 53 provided that checking only for the one electrical strand 60 and then for the other electrical strand 61 he follows.

It can be provided that the controller 2 and the further control 12 are only logically separated from each other, that is, that physically only a single control is formed, which for checking the rotor position angle 33 . 53 then successively each with one of the electrical strands 60 . 61 is connected. In this case, in addition, a corresponding circuit logic in the device 1 educated.

The further control 12 delivers as a result of the review another evaluation signal 17 ,

It is envisaged that checking the rotor position angle 33 . 53 Rotor position angle sensors 32 . 52 is performed only when a difference between a detected rotor attitude angle 33 the rotor position sensor 32 and a detected rotor attitude angle 53 the further rotor position angle sensor 52 reaches or exceeds a threshold.

It may further be provided that it is decided on the basis of the determined assessments which of the electrical strands 60 . 61 of the steering system is switched off or continued. For this purpose, the device comprises 1 a decision maker 8th based on the evaluation signals 7 . 17 the appropriate decision is made and in the form of a shutdown signal 9 outputs. The shutdown signal 9 can then be transmitted, for example, to a steering control or central control of a vehicle and further processed by these.

It can be provided that an error message 10 is output when at least one of the electrical strands 60 . 61 of the steering system is switched off or has been. The error message 10 For example, it can also be used by the decision maker 8th be generated and output.

It may further be provided that a rotor position angle, which is rated as defective 33 . 53 by a not rated as faulty rotor position angle 33 . 53 replaced by another rotor position sensor 32 . 53 was detected, with the not rated as faulty rotor position angle 33 . 53 to the appropriate control device 20 . 40 is transmitted. If, for example, it is determined that the rotor position angle 33 of an electric cord 60 is faulty, then the control device 20 this electrical strand 60 the rotor position angle 53 the other electrical strand 61 made available. In this way, the one electric strand 60 despite the faulty rotor position angle 33 or the incorrectly operating rotor position sensor 32 continue to provide a support torque for the steering system.

In 4 FIG. 3 is a schematic flow diagram of one embodiment of the method for checking a rotor attitude angle. The start 100 The method is performed after a difference between the detected in the individual electrical strands rotor position angles was detected in a multi-stranded steering system, for example, when the difference reaches or exceeds a value of 5 degrees.

In the process step 101 one of the electrical strands is selected. In this case, provision is made in particular for the electrical strands to be checked one after the other. In the process step 102 becomes the rotor position angle of the selected electrical string by performing the method steps 102-107 checked.

In one process step 103 a d-current is increased by means of a controller. Depending on whether the detected rotor position angle, with which the respective control device of the electrical string works, is correct or not, only a reactive power or, additionally, an active power in the electric machine increases.

In process step 104 is detected by increasing the d-current in the associated electrical strand, the rotor position angle by means of the rotor position angle sensor of the electrical string.

In process step 105 the detected rotor position angle is compared with an expected rotor position angle by means of a comparison device. If the increase in the d-current has merely led to an increase in the reactive power, the rotor position angle expected by the control device and the detected rotor position angle coincide. On the other hand, if increasing the d-current results in an increase in the active power as well, this leads to a change in the rotor position angle in the rotor, so that the detected rotor position angle and the expected rotor position angle do not coincide and have a difference from one another.

In the process step 106 the detected rotor position angle and / or the associated rotor position angle sensor on the basis of the comparison result from method step 105 evaluated by means of a rating device. This includes, in particular, a check as to whether, for example, a difference lies above a threshold value.

Subsequently, the evaluation result in the process step 107 output as evaluation signal by means of an output device.

In the process step 108 It is checked whether the rotor position angles of all electrical strings have already been checked. If this is not the case, then the next electrical strand is checked by the method steps 101 to 107 be repeated. If, however, all electrical strands are checked, then in one step 109 decided by means of a decision device, which of the electrical strands is turned off or which of the electrical strands will continue to operate.

LIST OF REFERENCE NUMBERS

1

contraption

2

control

3

input means

4

comparator

5

evaluator

6

output device

7

evaluation signal

8th

Decider

9

shutdown signal

10

error message

12

further control

13

further input device

14

further comparison device

15

further evaluation device

16

further output device

17

further evaluation signal

20

control device

21

electric machine

22

DC

23

phases

24

Four-quadrant

25

inverse Clarke transformation

26

Space vector modulation

27

control signals

28

PI control

29

q-current

30

d flow

31

Clarke-Park transformation

32

Rotor position angle sensor

33

detected rotor position angle

34

expected rotor position angle

40

control device

41

electric machine

52

additional rotor position sensor

53

Rotor position angle

60

electrical strand

61

electrical strand

63

engine

100-110

steps

Claims (7)

Method for checking a rotor position angle (33), wherein a rotor position angle sensor (33) detects the rotor position angle (33) of a rotor of a rotary electric field operated electric machine (21), and wherein the electric machine (21) by means of a control device (20) by a Vector control is controlled and for this purpose at least the detected rotor position angle (33) is evaluated by the control device (20), comprising the following steps: (a) increasing a d-current (30) by means of a controller (2), (b) detecting the rotor position angle (33) by means of the rotor position angle sensor (32), (c) comparing the detected rotor position angle (33) with an expected rotor position angle (34) by means of a comparison device (4), (d) evaluating the detected rotor position angle (33) and / or the rotor position angle sensor (32) on the basis of the comparison result by means of an evaluation device (5), (e) outputting the determined evaluation as evaluation signal (7) by means of an output device (6), wherein the method is additionally performed for a rotor position angle (53) detected by at least one further rotor position angle sensor (52), wherein the rotor position angle sensor (32) and the at least one further rotor position sensor (52) in different electrical strands (60, 61) of a steering system are arranged, each of the electrical strands (60, 61) next to the rotor position sensor (32, 52) each have an electric Machine (21, 41) and in each case a control device (20, 40), and wherein the steps (a) to (e) for the rotor position angle sensor (32) and the at least one further rotor position angle sensor (52) are performed only when a difference between a detected rotor position angle (33) of the rotor position sensor (32) and a detected rotor position angle (53 ) of the at least one further rotor position angle sensor (52) reaches or exceeds a threshold value. Method according to Claim 1 , characterized in that for evaluating a differential angle of the detected rotor position angle (33) and the expected rotor position angle (34) is determined, wherein the detected rotor position angle (33) and / or the rotor position sensor (32) are assessed as defective when the difference angle a Threshold reached or exceeded. Method according to one of the preceding claims, characterized in that it is decided on the basis of the determined assessments, which of the electrical strands (60, 61) of the steering system is switched off or continued to operate. Method according to Claim 3 characterized in that an error message (10) is issued when at least one of the electrical circuits (60, 61) of the steering system is or has been turned off. Method according to one of Claims 1 to 4 , characterized in that a rotor attitude angle (33, 53) assessed as faulty is replaced by a rotor attitude angle (33, 53) which is not considered faulty and which was detected by another rotor attitude angle sensor (32, 52), for which the one not rated as faulty Rotor position angle (33, 53) to the corresponding control device (20, 40) is transmitted. Device (1) for checking a rotor position angle (33), wherein a rotor position angle sensor (33) detects the rotor position angle (33) of a rotor of a rotary electric field operated electric machine (21), and wherein the electric machine (21) by means of a control device (20 ) is controlled by a vector control and for this purpose at least the detected rotor position angle (33) is evaluated by the control device (20), comprising: a controller (2), the controller (2) an input device (3), a comparison device (4), an evaluation device (5) and an output device (6), wherein the controller (2) is adapted to cause an increase of a d-current (30), and wherein the input device (3) is adapted to an after increasing of the d-current (30) detected rotor position angle (33) of the rotor position angle sensor (32) to receive, wherein the comparison means (4) is designed such, the detected rotor position angle ( 33) with an expected rotor attitude angle (34), and wherein the evaluation means (5) is arranged to evaluate the detected rotor attitude angle (33) and / or the rotor attitude angle sensor (32) based on the comparison result, and wherein the output means (6 The control unit (2) is further configured to perform the checking for at least one rotor position angle (53) detected by a further rotor position angle sensor (52), wherein the rotor position angle sensor (32 ) and the at least one further rotor position angle sensor (52) are arranged in different electrical strands (60, 61) of a steering system, wherein each of the electrical strands (60, 61) has, in addition to the rotor position angle sensor (32, 52), an electrical machine (21, 41 ) and in each case a control device (20, 40), and wherein the device (1) further comprises an activation device configured to activate the controller (2) for carrying out the checking when a difference between a detected rotor position angle (33) of the rotor position sensor (32) and a detected rotor position angle (53) of the at least one further rotor position sensor (52) reaches or exceeds a threshold. Steering system for a vehicle, comprising at least one device (1) according to Claim 6 ,

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