DE102011089341A1 - Method for determination of angle between stator and rotor of e.g. synchronous motor of electric vehicle, involves determining angle between stator and rotor based on electrical energy values and rotational angle between alternating fields - Google Patents

Abstract

The method involves feeding electrical periodical energy to coils of a type selected from a group of stator coils and rotor coils, so that spatial stationary magnetic alternating fields are formed in the respective coils. Values of electrical energy e.g. induced voltage and induced current, induced by the spatial stationary magnetic alternating field in other types of coils are measured by a measuring unit (104). An angle between a stator and a rotor is determined based on a rotational angle between the magnetic alternating fields, and the measured values of the electrical energy. Independent claims are also included for the following: (1) a device for determination of an angle between a stator and a rotor of an independently excited synchronous machine (2) a computer program for determination of an angle between a stator and a rotor of an independently excited synchronous machine.

Description

The invention relates to a method for determining an angle between a stator and a rotor of a separately excited synchronous machine. The invention further relates to a device for determining an angle between a stator and a rotor of a separately excited synchronous machine. The invention further relates to a motor control for an electric vehicle or for a hybrid vehicle and a computer program for determining an angle between a stator and a rotor of a separately excited synchronous machine.

For controlling a synchronous machine, in particular a synchronous machine in an electric and / or hybrid vehicle, phase currents, exciting current and rotor angle of the synchronous machine are measured. For a field-oriented control of the synchronous machine, in particular an exact knowledge of the rotor angle is important. The rotor angle is usually measured by means of a rotation angle sensor. How exactly the measured rotor angle indicates a position of the magnetic poles of the rotor substantially determines a quality of the control of the synchronous machine. For example, a difference between the measured rotor angle and the actual rotor angle can be reduced by specifying a suitable tolerance in a production of the rotation angle sensors and / or an adjustment when installing the rotation angle sensors. Furthermore, when replacing the rotation angle sensor in a workshop, it may also be necessary to redetermine the rotor angle.

Furthermore, the difference between the measured rotor angle and the actual rotor angle can be determined and taken into account for the regulation of the synchronous machine. For example, an actual rotor angle can be determined by the fact that the rotor is excited by means of an electrical excitation and actively rotated.

The rotor angle can then be determined via a voltage induced in the stator.

In the DE 10 2008 001 408 A1 For example, there is described a method of determining an offset angle of an electric machine that includes a stator, a rotor, and a shaft connected to the rotor. In the described method, the shaft is provided in a substantially no-load condition, the rotor being disposed to the stator at a field angle corresponding to the alignment of a rotor magnetic field generated by the rotor with the orientation of a stator magnetic field generated by the stator, wherein locating the rotor is an imprinting a standing or rotating stator magnetic field corresponding to the field angle. A sensor angle is detected by measurement with an angle sensor connected to the shaft, the detected sensor angle being associated with the field angle. The offset angle is provided as a function of the difference between field angle and sensor angle.

The invention has for its object to improve a control of a separately excited synchronous machine.

This object is solved by the subject matters of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect, a method for determining an angle between a stator and a rotor of a separately excited synchronous machine is described, wherein the stator has at least one stator coil and the rotor has at least one rotor coil. The method comprises (a) feeding a first electrical periodic excitation into at least one coil of one type of coil selected from the group of the stator coil and the rotor coil to form a first spatially stationary alternating magnetic field and (b) measuring a first one Value of an electrical quantity which is induced by means of the first spatially stationary alternating magnetic field in the other type of coil selected from the group of the stator coil and the rotor coil. Furthermore, the method (c) comprises feeding a second electrical periodic excitation in at least one coil of the one type of coil selected from the group of the stator coil and the rotor coil, so that a second spatially stationary alternating magnetic field is formed, which is relative to the and (d) measuring a second value of the electrical quantity selected by means of the second spatially stationary alternating magnetic field in the other type of coil selected from the group of the stator coil and the Rotor coil is induced. Moreover, the method (e) includes determining the angle between the stator and the rotor based on the predetermined first rotation angle, the measured first value of the electrical quantity, and the measured second value of the electrical quantity.

The term "electrical periodic excitation" may in this case be understood in particular to mean an electrical excitation which has a periodic course. For example, a periodic course may be sinusoidal. The periodic course can also be a non-sinusoidal course. For example, the course can be a sawtooth-shaped course. An electric Periodic excitation may in particular be a periodic current profile and / or a periodic voltage profile.

The term "magnetic alternating field" can be understood here in particular magnetic field, wherein the strength and polarity of the magnetic field change. In particular, an alternating magnetic field can be generated by means of alternating current and / or alternating voltage.

The term "spatially stationary" can be understood to mean that a field, in particular an alternating magnetic field, is generated at a fixed position in space and in particular relative to the stator or rotor of the synchronous machine. Furthermore, a spatially stationary field can be understood as meaning that the field is not subject to spatial propagation.

In particular, a geometric orientation of a spatially stationary field within a synchronous machine can remain the same.

The term "electrical quantity" can here be understood to mean a quantity which is indicative of an electric and / or magnetic field. For example, the electrical variable may be a current and / or a voltage.

The term "rotation angle" can be understood here as the angle by which a geometric orientation of the second spatially stationary alternating field is rotated relative to the first spatially stationary alternating field. For example, the angle of rotation may be 90 ° if the geometric orientation of the first spatially stationary alternating field is perpendicular to the geometric orientation of the second spatially stationary alternating field.

According to a further aspect, an apparatus for determining an angle between a stator and a rotor of a separately excited synchronous machine is described, wherein the stator has at least one stator coil and the rotor has at least one rotor coil. The apparatus comprises (a) means for injecting a first electrical periodic excitation and a second electrical periodic excitation into at least one coil of a type of coil selected from the group of (i) the stator coil and (ii) the rotor coil such that one of the first spatially stationary alternating magnetic field associated with the first electrical periodic excitation and second spatially stationary alternating magnetic field associated with the second electrical periodic excitation, the second spatially stationary alternating field being rotated by a predetermined first rotational angle with respect to the first spatially stationary alternating magnetic field ( b) a measuring device for measuring a first value of an electrical quantity which is induced by means of the first spatially stationary alternating magnetic field in the other type of coil selected from the group of (i) the stator coil and (ii) the rotor coil, and for measuring a second value of the electrical quantity induced by the second spatially stationary alternating magnetic field in the other type of coil selected from the group of (i) the stator coil and (ii) the rotor coil, and (c) a data processing device for Determining the angle between the stator and the rotor based on the predetermined first rotation angle, the measured first value of the electrical quantity, and the measured second value of the electrical quantity.

In particular, the means for injecting a first electrical periodic excitation and a second electrical periodic excitation may be adapted to also generate the excitations. Furthermore, the device may consist of two separate units: one unit for feeding the first electrical periodic excitation and another unit for feeding the second electrical periodic excitation. The device can also be designed as a unit.

The measuring device for measuring a first value and a second value may also be formed as a unit. However, it is also possible that the measuring device has a unit for measuring the first value and a unit for measuring the second value.

According to another aspect, a motor controller for an electric vehicle or for a hybrid vehicle is described, wherein the motor controller is configured to perform the above-mentioned or subsequently described method for determining an angle between a stator and a rotor of a separately excited synchronous machine.

In another aspect, a computer program for determining an angle between a stator and a rotor of a separately excited synchronous machine is described, wherein the computer program, when executed by a processor, performs the method of determining an angle between a stator and a rotor of a third-excited one Synchronous machine is set up.

For the purposes of this document, the mention of such a computer program is synonymous with the concept of a program element, a computer program product, and / or a computer-readable medium containing instructions for controlling a computer system in order to control the computer system To coordinate the operation of a system or a method in a suitable manner in order to achieve the effects associated with the method according to the invention.

The computer program may be implemented as a computer-readable instruction code in any suitable programming language such as JAVA, C ++, etc. The computer program can be stored on a computer-readable storage medium (CD-ROM, DVD, Blue-ray disk, removable drive, volatile or non-volatile memory, built-in memory / processor, etc.). The instruction code may program a computer or other programmable devices such as, in particular, an electric vehicle or hybrid vehicle control unit to perform the desired functions. Further, the computer program may be provided in a network, such as the Internet, from where it may be downloaded by a user as needed.

The invention can be implemented both by means of a computer program, i. H. a software, as well as by means of one or more special electronic circuits, d. H. in hardware or in any hybrid form, d. H. using software components and hardware components.

An angle between a stator and a rotor of a separately excited synchronous machine may in particular be the above-mentioned rotor angle. The stator or the rotor of the synchronous machine may have a plurality of coil pairs. A coil pair consists of two opposing coils. Each of these coils typically has multiple windings. In a separately excited synchronous machine, the coil pairs can be used to create a field of excitation. Usually, the coil pairs are arranged on a circle offset by 120 °. If a periodic electrical excitation is now fed into each coil pair, with the periodic electrical excitations having a temporal phase delay of 2π / 3 relative to one another, a so-called rotating field is obtained.

A spatially stationary alternating magnetic field can be obtained, for example, by feeding the periodic electrical excitations without temporal phase delay into the spatially offset coil pairs. By means of a suitable choice of an amplitude ratio of the periodic electrical excitations, a geometric orientation of the spatially stationary alternating field can be rotated. A possible periodic electrical excitation may be, for example, a sinusoidal current signal and / or voltage signal. However, a non-sinusoidal periodic electrical excitation may also be used.

Bringing a coil with several windings in a magnetic alternating field, so an electrical variable can be induced in the coil. In this case, the induced electrical variable shows a course in which the strength and polarity of the electrical variable change with the same periodicity as in the alternating magnetic field.

A value or an amount of the induced variable is inter alia dependent on an overlap of the alternating magnetic field with the coil. The more windings of a coil are traversed by an alternating magnetic field, the greater the amount of the induced variable can be. If, for example, the spatially stationary alternating magnetic field is formed in the stator of the synchronous machine, the amount of the variable induced in the rotor of the synchronous machine is dependent on the overlap of the spatially stationary alternating magnetic field with the rotor coils of the rotor. That is, the magnitude of the induced quantity is indicative of the angle between the stator and the rotor of the synchronous machine. If the spatially stationary alternating magnetic field is formed in the rotor of the synchronous machine, the amount of the induced electrical variable in the stator of the synchronous machine is analogous to the angle between the stator of the synchronous machine and the rotor of the synchronous machine.

If a geometrical orientation of the spatially stationary alternating field is changed, the overlap between the spatially stationary alternating magnetic field and the coils can also change. For example, the changed overlap may result in a changed value of the induced electrical quantity.

An advantage of the method for determining an angle between a stator and a rotor of a separately excited synchronous machine may be that no rotation of the rotor is necessary. Furthermore, it can be an advantage that no friction, in particular the synchronous machine, has to be taken into account when determining the angle. This may allow a simpler and more accurate determination of the angle between rotor and stator. If, for example, the externally excited synchronous machine is installed in a drive train of a hybrid or electric vehicle, it may be an advantage of the method described here that the wheels of the hybrid or electric vehicle need not be free for determining the angle between rotor and stator.

Hereinafter, exemplary embodiments will be described.

According to one embodiment of the method, the method further comprises (a) feeding a third electrical periodic excitation into at least one coil of the one type of coil selected from the group of (i) the stator coil and (ii) the rotor coil, so that a (b) measuring a third value of the electrical quantity generated by the third spatially stationary alternating magnetic field in the other type of Coil selected from the group of (i) the stator coil and (ii) the rotor coil is induced, and (c) determining the angle between the stator and the rotor based on the predetermined first rotation angle, the predetermined second rotation angle, the measured first value the electrical quantity, the measured second value of the electrical Gr and the measured third value of the electrical quantity.

In particular, it may be an advantage to determine the angle between stator and rotor based on the predetermined first rotation angle, the predetermined second rotation angle, the measured first value of the electrical quantity, the measured second value of the electrical quantity and the measured third value of the electrical quantity since this may allow to more accurately determine the angle between the stator and rotor of the synchronous machine.

According to a further embodiment of the method, the method further comprises (a) feeding further electrical periodic excitations into at least one coil of the one type of coil selected from the group of (i) the stator coil and (ii) the rotor coil, so that form further spatially stationary alternating magnetic fields, which are rotated in relation to the first spatially stationary alternating magnetic field by predetermined further rotation angles, (b) measuring further values of electrical magnitude, which by means of the other spatially stationary alternating magnetic fields in the other type of coil (c) recording a progression of the electrical quantity, wherein the course determines the first value as a function of a reference angle, the second value as a function of the reference angle plus first rotation angle, the third value depending on the Referenzwin kel plus the second angle of rotation and the other values depending on the reference angle plus the associated further rotation angle, (d) identifying a characteristic of the curve, and (e) determining the angle between the stator and the rotor based on the characteristic Property.

For example, the reference angle can be selected to be 0 °. It can be an advantage to determine the angle between stator and rotor from the characteristic properties of the curve, since the angle between stator and rotor of the synchronous machine can thus be determined particularly accurately.

According to a further embodiment of the method, the characteristic property of the course is a zero crossing of the course and / or an extreme value of the course.

In particular, the zero crossing and / or the extreme value of the profile can be determined particularly accurately.

According to a further embodiment of the method, the characteristic of the curve is determined based on an average of two predetermined angles of rotation, wherein the two predetermined angles of rotation have an equal magnitude of the measured value of the electrical quantity.

Does the synchronous machine, for example, pronounced poles, z. As a salient pole, so in particular the zero crossings and / or the extreme values of the course of the electrical variable can be smoothed.

According to a further embodiment of the method, the electrical quantity is an induced voltage and / or an induced current.

For example, the induced voltage can be measured by leaving the winding of the stator coils or rotor coils open and measuring the voltage. Closing the windings of the stator coils or of the rotor coils briefly, one can measure an induced current. In particular, the electrical variable can also be determined from a controller output variable. For example, a rotor current control can actively control to a setpoint If * = OA. In this case, a regulator output voltage Uf * could be indicative of the electrical quantity.

According to a further embodiment of the method, an offset angle of the sensor element is determined from a difference between the specific angle between the stator and the rotor and a further angle, wherein the further angle is determined by a sensor element.

In particular, a control of the synchronous machine can be improved by means of the specific offset angle.

It should be noted that embodiments of the invention have been described with reference to different subject matters. In particular, some embodiments of the invention are described with apparatus claims and other embodiments of the invention with method claims. However, it will be readily apparent to those skilled in the art upon reading this application that, unless explicitly stated otherwise, in addition to a combination of features belonging to a type of subject matter, any combination of features that may result in different types of features is also possible Subject matters belong.

Further advantages and features of the present invention will become apparent from the following exemplary description of presently preferred embodiments.

1 shows an apparatus for determining an angle of a synchronous machine.

2 shows a control structure for a synchronous machine.

3 shows a course of an induced electrical variable as a function of a rotation angle.

4 shows a smoothed course of an induced electrical variable as a function of a rotation angle.

In order to avoid unnecessary repetitions, features or components already explained on the basis of a previously described embodiment will not be explained in detail later.

It should also be noted that the embodiments described below represent only a limited selection of possible embodiments of the invention. In particular, it is possible to suitably combine the features of individual embodiments with one another, so that a multiplicity of different embodiments are to be regarded as obviously disclosed to the person skilled in the art with the embodiment variants explicitly illustrated here.

1 shows a device 100 for determining an angle of a synchronous machine, wherein the synchronous machine comprises a rotor and a stator. The device 100 has a facility 102 for feeding a first electrical excitation and a second electrical excitation into at least one coil of a rotor or a stator of the synchronous machine. By supplying the first electrical excitation and the second electrical excitation, a first spatially stationary alternating magnetic field associated with the first electrical periodic excitation and a second spatially stationary alternating magnetic field associated with the second electrical periodic excitation can be formed. In particular, the second spatially stationary alternating field is rotated relative to the first spatially stationary alternating magnetic field by a predetermined first rotation angle.

Furthermore, the device 100 a measuring device 104 on. The measuring device 104 is set to measure a value of an electrical quantity which is induced by means of the first spatially stationary alternating magnetic field and by means of the second spatially stationary alternating magnetic field in the rotor or the stator of the synchronous machine.

From the predetermined first rotation angle, the measured first value of the electrical quantity and the measured second value of the electrical quantity can be in a data processing device 106 the angle between the stator and the rotor can be determined.

2 shows a block diagram of a control for a synchronous machine according to the prior art. From a current setpoint unit 202 become a current setpoint If * 236 for a rotor winding as well as current setpoints 222 for stator windings in the so-called d / q system. The current setpoint If * 236 for the rotor winding of a synchronous machine is powered by a rotor 204 used as input signal. At the exit 226 of the rotor current controller 204 is a rotor voltage Uf * available, which is applied to the rotor winding of the synchronous machine. A current sensor 214 Measures the current through the rotor winding and carries the measured value 216 back into the rotor current regulator 204 , In addition, the synchronous machine owns 234 three stator windings with stator voltages 220 a voltage transformation unit 208 be supplied. The voltage transformation unit 208 gets voltage setpoints 224 for the stator windings in the d / q system from a d / q current regulator 206 provided as input signals. The d / q current controller 206 is again with the current setpoint unit 202 over the wires 222 connected. On the wires 222 Current setpoints for the stator windings are in the so-called d / q system to the d / q current controller 206 specified.

In addition, via current sensors 219 measured stator currents 218 a power transformation unit 210 fed. This transforms the measured stator currents 218 in measured stator currents in the d / q system and delivers these signals via the wires 228 to the d / q current controller 206 , In addition, an angle sensor 232 provided, the rotational movement of the rotor of the synchronous machine 234 and thus measures the angle between the stator and the rotor of the synchronous machine. In an angle detection unit 212 become the signals of the angle sensor 232 evaluated.

However, commercial angle sensors do not provide an ideal angle signal that is 100% consistent with reality. For example, there may be a difference between the angle between the rotor and the stator and the angle determined by the angle sensor. This difference is called the offset angle.

If a faulty angle signal is used as a control signal for a control of a synchronous machine, this can have a negative effect on the efficiency of the control. For this reason, an output signal 230 the angle detection unit 212 an offset angle correction unit 240 be supplied. The corrected angle signal 231 then becomes the stream transformation unit 210 and the voltage transformation unit 208 fed.

3 shows a course 300 an induced electrical quantity as a function of a rotation angle. It is on the abscissa 301 plotted a rotation angle about which a second spatially stationary alternating field is rotated with respect to a first spatially stationary alternating field. A geometric orientation of the first spatially stationary alternating field is given by means of a reference angle. In the illustrated course 300 the reference angle was chosen to be 0 °. On the ordinate 302 the value of the induced electrical quantity is plotted. The points 303 and 305 make extreme values of the course 300 , the point 304 a zero crossing of the course 300 represents.

4 shows a course smoothed in extreme values and zero crossings 400 an induced electrical quantity as a function of a rotation angle. Such a smoothed course 400 can occur, for example, in a synchronous machine with pronounced poles. On the abscissa 401 in turn, the angle of rotation is plotted around which the second spatially stationary alternating field is rotated with respect to the first spatially stationary alternating field. The geometric orientation of the first spatially stationary alternating field is in turn given by means of the reference angle. In the illustrated course 400 the reference angle was also chosen to be 0 °. On the ordinate 402 the value of the induced electrical quantity is plotted. The points 403 and 404 represent angles of rotation which have the same amount of induced electrical quantity. From the mean of the two angles of rotation, which to the two points 403 and 404 a position of an extreme value can be determined. The two points 404 and 405 also represent angles of rotation which have the same amount of induced electrical quantity, but with different signs. From the mean of the two angles of rotation, which to the two points 404 and 405 a position of a zero crossing can be determined.

In summary, it remains to be stated: A spatially stationary alternating magnetic field can induce an electrical variable (voltage and / or current) not only in a transformer but also in a coil of a separately excited synchronous machine. This is due to the fact that a separately excited synchronous machine has a stator with stator coils and a rotor with rotor coils. If a periodic electrical excitation is fed, for example, into the stator coils of the synchronous machine, then a spatially stationary alternating magnetic field can form in the stator of the synchronous machine. In particular, this spatially stationary alternating magnetic field can have a fixed geometric orientation with respect to the stator of the synchronous machine. The spatially stationary alternating magnetic field can induce an electrical quantity in the rotor coils. A value of the induced electrical variable is dependent in particular on an overlap of the spatially stationary alternating magnetic field with the rotor coils and thus on a position of the rotor. If the periodic electrical excitation is fed into the rotor coils of the rotor of the synchronous machine, the spatially stationary alternating field is formed in the rotor of the synchronous machine. The electrical quantity is then induced in the stator coils of the stator of the synchronous machine.

In particular, an advantage of the method described may be that an angle between the stator and the rotor of the synchronous machine can be determined without the rotor in the stator having to be rotated for this purpose.

In addition, it should be noted that "having" does not exclude other elements or steps, and "a" or "an" does not exclude a multitude. Reference signs in the claims are not to be considered as limiting.

LIST OF REFERENCE NUMBERS

100

contraption

102

Facility

104

measuring device

106

Data processing device

202

Current Setpoints Units

204

Rotor current controller

206

d / q-current regulator

208

Voltage transformation unit

210

Current transformation unit

212

Angle detection unit

214

current sensor

216

Current through rotor winding

218

measured currents through stator windings

219

Current sensors for currents through stator windings

220

Voltages on stator windings

222

Current setpoints through stator windings in the d / q system

224

Voltage setpoints through stator windings in the d / q system

226

Output voltage of the rotor current controller, voltage at the rotor winding

228

measured stator currents in the d / q system

230

Output signal of the angle detection unit

231

Output signal of the offset angle correction unit

232

angle sensor

234

synchronous machine

236

Current setpoint for rotor winding

240

Offset angle correction unit

300

course

301

abscissa

302

ordinate

303

maximum

304

Zero-crossing

305

minimum

400

course

401

abscissa

402

ordinate

403

Point

404

Point

405

Point

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102008001408 A1 [0005]

Claims (10)

Method for determining an angle between a stator and a rotor of a separately excited synchronous machine ( 234 ), wherein the stator has at least one stator coil and the rotor has at least one rotor coil, the method comprising: feeding a first electrical periodic excitation into at least one coil of one kind of coil selected from the group of (a) the stator coil and (b) the rotor coil such that a first spatially stationary alternating magnetic field is formed, measuring a first value of an electrical quantity determined by the first spatially stationary alternating magnetic field in the other type of coil selected from the group of (a) the stator coil and (b) the rotor coil feeding a second electrical periodic excitation in at least one coil of the one type of coil selected from the group of (a) the stator coil and (b) the rotor coil so as to form a second spatially stationary alternating magnetic field related to the first spatially stationary alternating magnetic field by a predetermined n first rotation angle, measuring a second value of the electrical quantity induced by the second spatially stationary alternating magnetic field in the other type of coil selected from the group of (a) the stator coil and (b) the rotor coil, and determining the Angle between the stator and the rotor based on the predetermined first rotation angle, the measured first value of the electrical quantity and the measured second value of the electrical quantity. A method according to the preceding claim, the method further comprising: Feeding a third electrical periodic excitation into at least one coil of the one type of coil selected from the group of (a) the stator coil and (b) the rotor coil so as to form a third spatially stationary alternating magnetic field which is spatially relative to the first stationary alternating magnetic field is rotated by a predetermined second rotation angle, Measuring a third value of the electrical quantity induced by the third spatially stationary alternating magnetic field in the other type of coil selected from the group of (a) the stator coil and (b) the rotor coil, and Determining the angle between the stator and the rotor based on the predetermined first rotation angle, the predetermined second rotation angle, the measured first value of the electrical quantity, the measured second value of the electrical quantity and the measured third value of the electrical quantity. Method according to one of the preceding claims, the method further comprising: feeding further electrical periodic excitation into at least one coil of the one type of coil selected from the group of (a) the stator coil and (b) the rotor coil so that further spatially stationary ones forming alternating magnetic fields which are rotated by predetermined further rotational angles with respect to the first spatially stationary alternating magnetic field, measuring further values of the electrical quantity selected by means of the further spatially stationary alternating magnetic fields in the other type of coil selected from the group of (a ) of the stator coil and (b) the rotor coil is induced to record a trace ( 300 . 400 ) of the electrical quantity, the course ( 300 . 400 ) the first value depending on a reference angle, the second value depending on the reference angle plus the first rotation angle, the third value depending on the reference angle plus the second rotation angle and the further values depending on the reference angle plus the respectively associated further rotation angle, identifying a characteristic property ( 303 . 304 . 305 ) of the course ( 300 . 400 ), and determining the angle between the stator and the rotor based on the characteristic property ( 303 . 304 . 305 ). Method according to claim 3, wherein the characteristic property ( 303 . 304 . 305 ) of the course ( 300 ) a zero crossing of the course ( 304 ) and / or an extreme value ( 303 . 305 ) of the course. Method according to claim 3, wherein the characteristic property of the course is determined on the basis of an average value of two predetermined angles of rotation, the two predetermined angles of rotation ( 403 . 404 . 405 ) have an equal amount of the measured value of the electrical quantity. Method according to one of the preceding claims, wherein the electrical quantity is an induced voltage and / or an induced current. Method according to one of the preceding claims, wherein a difference between the determined angle between the stator and the rotor and a further angle, wherein the further angle of a sensor element ( 232 ), an offset angle of the sensor element ( 232 ) is determined. Contraption ( 100 ) for determining an angle between a stator and a rotor of a separately excited synchronous machine, wherein the stator has at least one stator coil and the rotor has at least one rotor coil, the device comprising: An institution ( 102 ) for inputting a first electrical periodic excitation and a second electrical periodic excitation into at least one coil of a type of coil selected from the group of (a) the stator coil and (b) the rotor coil so that a first associated with the first electrical periodic excitation spatially stationary magnetic alternating field and a second spatially stationary alternating magnetic field associated with the second electrical periodic excitation, wherein the second spatially stationary alternating field is rotated with respect to the first spatially stationary alternating magnetic field by a predetermined first rotational angle, a measuring device ( 104 ) for measuring a first value of an electrical quantity induced by means of the first spatially stationary alternating magnetic field in the other type of coil selected from the group of (a) the stator coil and (b) the rotor coil, and measuring a second value of electrical quantity, which is induced by means of the second spatially stationary alternating magnetic field in the other type of coil selected from the group of (a) the stator coil and (b) the rotor coil, and a data processing device ( 106 ) for determining the angle between the stator and the rotor based on the predetermined first rotation angle, the measured first value of the electrical quantity, and the measured second value of the electrical quantity. A motor controller for an electric vehicle or for a hybrid vehicle, wherein the motor controller is configured to perform the method according to one of claims 1 to 7 for determining an angle between a stator and a rotor of a separately excited synchronous machine. A computer program for determining an angle between a stator and a rotor of a separately excited synchronous machine, wherein the computer program, when executed by a processor, is adapted to perform the method of any one of claims 1 to 7.

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