Control method, calibration method and electric motor

Abstract

The invention relates to a control method for an electric motor (10), in particular a brushless DC motor, preferably a permanent-magnet-excited synchronous motor, comprising a stator (14) having at least one coil (12) and comprising a rotor (18) having at least one permanent magnet (16), which rotor, during operation, is rotated relative to the stator (14), and comprising an open- and / or closed-loop control unit (20), in particular a microprocessor, by means of which, depending on a rotational angle (22) of the rotor (18) to the stator (14), an output voltage (24) for driving the rotor (18) is specified. It is proposed that the output voltage (24) is specified such that a harmonic coil current (28) flowing during operation, in particular in addition to a basic oscillation coil current, is set at least substantially to a value determined in at least one calibration step (30).

Description

[0001] Description Calibration procedure and electric motor

[0002] State of the art

[0003] A control method for an electric motor with a stator having at least one coil and with a rotor having at least one permanent magnet, which is rotated relative to the stator during operation, and with at least one control and / or regulating unit, in particular a microprocessor, with which an output voltage for driving the rotor is specified depending on an angle of rotation of the rotor to the stator, has already been proposed.

[0004] Disclosure of the invention

[0005] The invention is based on a control method for an electric motor, in particular a brushless DC electric motor, preferably a permanent magnet excited synchronous motor, with a stator having at least one coil and with a rotor having at least one permanent magnet, which is rotated relative to the stator during operation, and with at least one control and / or regulating unit, in particular a microprocessor, with which an output voltage for driving the rotor is specified depending on an angle of rotation of the rotor to the stator.

[0006] It is proposed that the output voltage be specified in such a way that a harmonic coil current flowing during operation, in particular in addition to a fundamental oscillation current, is at least substantially set to a value determined in at least one calibration step. The inventive design of the control method can advantageously provide a high level of comfort, since in particular the setting of the harmonic coil current ensures low vibration-related noise emissions NVH (Noise Vibration Harshness). Advantageously, particularly precise operation can be provided, since in particular the setting of the harmonic coil current can prevent the occurrence of torque fluctuations, preferably torque ripple. Advantageously, low costs can be provided, since in particular existing drives can be improved with an update.Advantageously, a particularly high performance can be provided at advantageously constant costs, since, in particular, by adjusting the harmonic coil current, a low noise emission can be achieved while at the same time requiring low computing power of the control and / or regulating unit.

[0007] The electric motor is preferably designed as a brushless direct current motor (BLDC). In particular, the BLDC is designed as a permanently excited synchronous motor. The electric motor is preferably designed as an external rotor electric motor. Alternatively, the electric motor could also be designed as an internal rotor electric motor. The electric motor preferably has an electronic circuit, preferably an inverter circuit, which converts at least one direct current for an electrical power supply of the electric motor into a multi-phase alternating current, in particular three-phase current. The electric motor preferably has a stator which comprises at least one, preferably at least three coils. The rotor preferably has at least one, preferably at least two permanent magnets. In particular, the at least one permanent magnet has at least one pole, preferably at least two different poles.It is conceivable for the rotor to have a plurality of permanent magnets, in particular arranged around a circumference of the rotor, which have north and south poles arranged, preferably alternately, around the circumference of the rotor. Preferably, the number of coils in the stator is greater than the number of permanent magnets in the rotor. It is conceivable for the stator to have the same number of coils as the number of permanent magnets in the rotor. Preferably, the electric motor has at least one control and / or regulating unit. Preferably, the control and / or regulating unit is designed as a microcontroller. Alternatively, the control and / or regulating unit could be designed at least partially as a cloud. Preferably, the control and / or regulating unit is configured to specify at least one output voltage signal for driving the electric motor.Preferably, the electronic circuit generates the output voltage specified by the control and / or regulating unit. A "control and / or regulating unit" is understood in particular to mean a unit with at least one control electronics unit. A "control electronics unit" is understood in particular to mean a unit with a processor unit and a memory unit, as well as with an operating program stored in the memory unit. A "microcontroller" is understood in particular to mean at least one electronic component, such as a semiconductor chip, which has a processor and / or RAM and program memory and / or peripheral functions.

[0008] Preferably, the output voltage signal provided by the control and / or regulating unit is converted into an output voltage. Preferably, the output voltage is generated and / or converted by the electronic circuit. Preferably, a multi-phase, in particular three-phase, alternating current is generated by the electronic circuit. Preferably, the output voltage signal depends on the angle of rotation of the rotor to the stator. Preferably, the coil voltage has a change of sign upon rotation of the rotor, which change is repeated, in particular periodically. Preferably, during operation of the electric motor, preferably upon rotation of the rotor about the stator and / or upon provision of a motor torque, a preferably sinusoidal fundamental oscillation coil current is generated from the output voltage applied to the at least one coil.Preferably, a coil voltage is induced in the coils of the stator by the permanent magnets, particularly during a movement of the rotor, which generates a harmonic coil current superimposed on the fundamental coil current, in particular an integer multiple of the fundamental coil current. Preferably, the harmonic coil current is generated by the induced harmonic coil voltage. Preferably, the harmonic coil current depends at least on a coil resistance and a coil inductance. Preferably, the harmonic coil current is changed by changing / adjusting a difference between the induced harmonic coil voltage and the output voltage provided by the electronic circuit. Preferably, the harmonic coil current is reduced or eliminated by adjusting the output voltage to the induced harmonic coil voltage.Preferably, the output voltage is predetermined such that a harmonic coil current flowing during operation, in particular in addition to a fundamental coil current, is at least substantially adjusted to a value determined in at least one calibration step. In particular, the harmonic coil current is influenced by operating parameters and / or material properties and / or manufacturing tolerances and / or design and / or the like.

[0009] Preferably, the calibration step determines at least the value for the harmonic coil current at which low-noise and / or torque-ripple-free operation is provided. The term "harmonic" refers in particular to an oscillation that is a, preferably integer, multiple of the frequency of a fundamental oscillation. For example, the harmonic oscillation could be determined using a Fourier transformation, in particular a Fast Fourier Transformation, or a comparable mathematical method.

[0010] Preferably, the harmonic coil current is adjusted by the control and / or regulating unit by specifying the output voltage as a function of the rotor's rotation angle. In particular, the harmonic coil current is controlled / adjusted by the control and / or regulating unit in an open-loop system. An "open-loop system" is understood to mean, in particular, a control process, preferably for controlling the harmonic coil voltage. In particular, the open-loop system is free of feedback, for example, of the coil current, within the control path.

[0011] It is further proposed that the harmonic coil current is at least substantially eliminated by setting the value determined in the calibration step to zero. Advantageously, a high level of comfort can be provided since, in particular, a very small / no harmonic coil current results in particularly low noise emissions. Advantageously, low costs can be provided since, in particular, the value zero represents a very good approximation for many electric motors / operating conditions. Advantageously, low calibration complexity can be provided since, in particular, the value zero represents a very good approximation for most electric motors and, as a result, calibration to determine the optimal harmonic coil current can be dispensed with. Preferably, the electric motor is operated at least substantially free of a harmonic coil current. Preferably, the electric motor is operated at a very small harmonic coil current.In this context, “at least substantially” should be understood to mean that a deviation from a predetermined value deviates in particular by less than 25%, preferably less than 10%, particularly preferably less than 5% and particularly preferably less than 1% of the fundamental oscillation coil current.

[0012] Furthermore, it is proposed that the harmonic coil current be adjusted by adapting the output voltage to the harmonic coil voltage induced by the at least one permanent magnet, or at least approximating it. Advantageously, a high level of comfort can be provided, since particularly low noise emissions can be achieved due to the very small harmonic coil current. Advantageously, low costs can be provided, since particularly by adjusting the harmonic coil current, the computing power of the control and / or regulating unit can be kept low. Preferably, for each coil, a harmonic difference voltage is determined between the total coil voltage, in particular occurring during operation, and a fundamental coil voltage provided by the electronic circuit, by means of which the output voltage is adapted or at least approximated.Preferably, the output voltage provided by the electronic circuit is adjusted such that the electric motor is operated at least substantially free of the harmonic differential voltage or at a reduced harmonic differential voltage. In particular, the harmonic differential voltage between the induced harmonic coil voltage and the output voltage is at least reduced by the adjustment / approximation of the output voltage. An "adjustment" should be understood in particular as an approximation of an actual value to a target value, in particular an adjustment of two values ​​to one another. An "approximation" should be understood in particular as a reduction of a difference between two values, where the difference is greater than zero.

[0013] Furthermore, it is proposed that a relationship between the output voltage and the angle of rotation of the rotor be described via a sinusoidal waveform with harmonic voltage modulation, which takes into account a harmonic coil voltage oscillation, preferably a harmonic voltage, generated by the at least one permanent magnet. Advantageously, a high level of comfort can be provided, since, in particular, a very small or no harmonic coil current results in particularly low noise emissions. Advantageously, low costs can be provided, since existing electric motors can be improved by updating them with new, in particular harmonic-modulated sinusoidal waves. Preferably, during harmonic voltage modulation, a harmonic voltage is applied to the fundamental coil voltage.Preferably, the harmonic voltage is configured as a harmonic, in particular an integer multiple, of the fundamental voltage. For example, the harmonic output voltage profile could be configured to be at least substantially identical to the entire harmonic coil voltage. During harmonic modulation, the fundamental coil voltage is preferably added to the harmonic harmonic voltage.

[0014] In addition, it is proposed that the output voltage be stored in the control and / or regulating unit based on a table of values, preferably determined during calibration of the electric motor. This can advantageously provide a high level of comfort, since in particular a very small / no harmonic coil current results in particularly low noise emissions. This can advantageously provide particularly precise operation, since in particular the adjustment of the harmonic coil current can prevent the occurrence of torque fluctuations, preferably torque ripple. This can advantageously provide low costs, since in particular existing drives can be improved with an update. This can advantageously provide low costs, since in particular the adjustment of the harmonic coil current can keep the computing power of the control and / or regulating unit low.The value table preferably contains a number of rotation angles of the rotor relative to the stator, preferably evenly distributed over one revolution, each of which is assigned an output voltage. It is conceivable that the values ​​in the table can be linearly interpolated in order to be able to specify an output voltage signal for intermediate values ​​of the rotation angle. For example, the relationship between the output voltage and the rotation angle of the rotor could be described as the harmonic voltage-modulated sine waveform, which is divided into discrete angular steps. "Discrete angular steps" should be understood in particular as an integer and finite number of values ​​for the rotation angle, which are preferably spaced apart from one another and non-overlapping.

[0015] It is further proposed that the output voltage be stored in the control and / or regulating unit as an algebraic function, preferably determined during calibration of the electric motor. Advantageously, a high level of comfort can be provided, since in particular a reduced harmonic coil current results in particularly low noise emissions. Advantageously, particularly precise operation can be provided, since in particular the adjustment of the harmonic coil current can prevent the occurrence of torque fluctuations, preferably torque ripple. Advantageously, low costs can be provided, since in particular existing drives can be improved with an update. Advantageously, low costs can be provided, since in particular the adjustment of the harmonic coil current can keep the computing power of the control and / or regulating unit low.For example, the relationship between the output voltage and the rotor's rotation angle could be described as the harmonic voltage-modulated sinusoidal waveform, which is described exactly or at least approximately using the algebraic function. An "algebraic function" is understood in particular as a mathematical relationship between two quantities that are continuously described at least within a range of values. Furthermore, it is proposed that the relationship between the output voltage and the motor's rotation angle be specified as a function of at least one operating parameter, in particular motor load, motor speed, motor temperature, and / or operating voltage.Advantageously, a particularly high level of comfort can be provided, since in particular the consideration of the operating parameters results in a particularly low noise emission. Preferably, the value for the harmonic coil current is influenced by at least one of the operating parameters.

[0016] In addition, it is proposed that a plurality of value tables or a set of algebraic functions be assigned to different operating states, which are selected during operation depending on the operating parameters. Advantageously, a particularly high level of comfort can be provided, since, in particular, the consideration of the operating parameters results in particularly low noise emissions, preferably in all operating states. Preferably, a plurality of value tables are stored in the control and / or regulating unit, which can be selected depending on the operating states and / or the operating parameters for specifying the output voltage. Preferably, each value table is assigned a value range of the operating state and / or the operating parameter.Alternatively, a set of algebraic functions could be stored in the control and / or regulation unit, which could be adapted to operating states and / or operating parameters, for example, via parameterization. It is conceivable that the parameterized set of algebraic functions could be used to perform a continuous adaptation to the operating states and / or operating parameters.

[0017] Furthermore, a calibration method for determining parameters, in particular for the control method, is proposed, wherein the calibration step is preferably carried out individually for each motor. Advantageously, a high level of comfort can be provided, since operation with the output voltages determined by calibration ensures particularly quiet operation of the electric motor. Preferably, a value for the harmonic coil current is determined in at least one sub-step of the calibration step. Preferably, the value of the harmonic coil current represents an optimal value at which NVH stress is low and torque ripple is minimized. Preferably, the optimal value for the harmonic coil current is determined exemplarily for one electric motor, for example by averaging several electric motors in a series, and is applied to all electric motors in the series in series production.Alternatively, it would be conceivable for the optimum value to be determined individually for each electric motor in a manufacturing process. It is also conceivable for the optimum value to be determined anew each time the electric motor is repaired / maintained, for example by carrying out a new calibration. Preferably, in at least one further sub-step of the calibration step, the output voltages are determined at which the electric motor is operated at least substantially with the value of the harmonic coil current. Preferably, in the further calibration step, the electric motor is operated in such a way that the harmonic coil current is regulated and the output voltages for the angles of rotation for achieving the value for the harmonic coil current are read out. Preferably, in a further sub-step of the calibration step, the determined output voltages are made available to the control and / or regulating unit.It is conceivable that calibration could reduce the influence of manufacturing tolerances on NVH emissions. "Parameters" in this context refer, in particular, to the output voltages as a function of the rotation angle of the rotor relative to the stator.

[0018] Furthermore, an electric motor with the control method described above is proposed. Advantageously, a high level of comfort can be provided, since the electric motor, in particular, enables particularly quiet operation. Advantageously, an electric motor can be provided at low cost, since, in particular, the control method of the electric motor requires only low computing power, thus allowing the installation of a cost-effective control and / or regulating unit.

[0019] The control method according to the invention, the calibration method according to the invention, and the electric motor according to the invention are not intended to be limited to the application and embodiment described above. In particular, the control method according to the invention, the calibration method according to the invention, and the electric motor according to the invention may have a number of individual elements, components, units, and method steps that differs from the number stated herein to fulfill a functionality described herein. Furthermore, in the value ranges specified in this disclosure, values ​​within the stated limits are also to be considered disclosed and can be used arbitrarily.

[0020] drawing

[0021] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an exemplary embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also expediently consider the features individually and combine them into useful further combinations.

[0022] They show:

[0023] Fig. 1 an electric motor with a rotor and a stator,

[0024] Fig. 2 is a schematic equivalent circuit diagram of the electric motor with a harmonic coil current,

[0025] Fig. 3 is a schematic representation of a vibration diagram, Fig. 4 is a schematic flow diagram of a control method for the electric motor and

[0026] Fig. 5 is a schematic flow diagram of a calibration procedure.

[0027] Description of the embodiment

[0028] Figure 1 shows an electric motor 10. The electric motor 10 is designed as a brushless DC electric motor. The electric motor 10 is designed as a permanent magnet synchronous motor. The electric motor 10 is designed as an internal rotor electric motor. The electric motor 10 could also be designed as an external rotor electric motor. The electric motor 10 has a stator 14. The stator 14 has three coils 12. The three coils 12 are offset from one another by an electrical angle of 120°. Alternatively, the stator 14 could also have a number of coils 12 different from three. The electric motor 10 has a rotor 18. The rotor 18 has an electrical angle of rotation 22 to the stator 14. The electrical angle of rotation 22 has a value between 0° and ±360°. When the rotor 18 rotates, the angle of rotation 22 is repeated with each revolution. The rotor 18 has two permanent magnets 16.The two permanent magnets 16 have different polarities. The electric motor 10 could also have one of two different numbers of permanent magnets 16. The electric motor 10 has a control and / or regulating unit 20. The control and / or regulating unit 20 is designed as a microprocessor. The control and / or regulating unit 20 is configured to output an output voltage signal 44 to control the electric motor 10 as a function of the angle of rotation 22 of the rotor 18 to the stator 14, see Fig. 2. The electric motor 10 has an electronic circuit 34. The electronic circuit 34 is designed as an inverter circuit. The inverter circuit is configured to convert a direct current to an electrical power supply of the electric motor 10 into a multi-phase alternating current. The multi-phase alternating current is three-phase.The electronic circuit 34 provides an output voltage 24 to the coils 12, see Fig. 2. The electronic circuit 34 converts the output voltage signal 44 specified by the control and / or regulating unit 20 into an output voltage 24.

[0029] Figure 2 shows a schematic equivalent circuit diagram 36 of the electric motor 10. The control and / or regulating unit 20 has a value table 46. Alternatively or additionally, the control and / or regulating unit 20 could also have an algebraic function 48. The value table 46 or the algebraic function 48 shows a relationship between the angle of rotation 22 and the output voltage signal 44. The control and / or regulating unit 20 provides the electronic circuit 34 with the associated output voltage signal 44 for the angle of rotation 22 of the rotor 18. The electronic circuit 34 converts the output voltage signal 44 into the output voltage 24. The electric motor 10 is driven by the output voltage 24. The electric motor 10 has a resistor 38. The electric motor 10 has an inductance 40. During a relative movement between the rotor 18 and the stator 14, a coil voltage 58 is generated at the coils 12 (see Fig. 1).The coil voltage 58 has an induced harmonic coil voltage 32. The induced harmonic coil voltage 32 is formed as a harmonic differential voltage 42 between the output voltage 24 and a coil voltage 58. The harmonic differential voltage 42 causes a harmonic coil current 28. The harmonic coil current 28 causes increased NVH emissions. The output voltage 24 specified by the control and / or regulating unit 20 is approximately equal to the coil voltage 58, which is why the harmonic differential voltage 42 is approximately zero. The harmonic coil current 28 generated by the harmonic differential voltage 42 is therefore very small. A small harmonic coil current 28 causes low NVH emissions. Alternatively, the harmonic coil current 28 could be set to an optimal value. The optimal value for the harmonic coil current 28 reduces NVH emissions and prevents torque fluctuations (torque ripple).

[0030] Figure 3 shows a schematic oscillation diagram 50. The schematic oscillation diagram 50 has an ordinate 52. An electrical voltage is plotted on the ordinate 52. The schematic oscillation diagram 50 has an abscissa 54. The angle of rotation 22 of the rotor 18 relative to the stator 14 is plotted on the abscissa 54. The schematic oscillation diagram 50 shows the relationship between the angle of rotation 22 and the output voltage 24. The output voltage 24 has a harmonic-modulated sinusoidal waveform. The output voltage 24 is formed by a fundamental coil voltage 56 added to the induced harmonic coil voltage 32. The harmonic-modulated output voltage 24 causes the harmonic difference voltage 42 to become zero. The electric motor 10 has no additional harmonic coil current 28 during operation when the harmonic difference voltage 42 is zero.The electric motor 10 therefore has only a sinusoidal fundamental coil current. Alternatively, any harmonic coil current 28 can be set by adjusting an amplitude and / or a phase during the harmonic modulation of the sinusoidal fundamental coil voltage 56. Figure 4 shows a schematic flow diagram of a control method for the electric motor 10.

[0031] In a method step 60, the angle of rotation 22 from the rotor 18 to the stator 14 is determined. The angle of rotation 22 is determined at regular intervals. The determined angle of rotation 22 is transmitted to the control and / or regulating unit 20. In addition, further operating parameters could be transmitted to the control and / or regulating unit 20. The operating parameters could be embodied as an engine load and / or an engine speed and / or an engine temperature and / or an operating voltage and / or further parameters that appear appropriate to a person skilled in the art.

[0032] In a further method step 62, the control and / or regulating unit 20 reads the output voltage signal 44 associated with the transmitted angle of rotation 22 from the value table 46. The output voltage signal 44 is linearly interpolated if the transmitted angle of rotation 22 lies between two values ​​for the angles of rotation 22. Alternatively, the output voltage signal 44 could be calculated by the control and / or regulating unit 20 using the algebraic function 48 as a function of the transmitted angle of rotation 22. The relationship between the output voltage 24 and the angle of rotation 22 of the rotor 18 to the stator 14 is described via a sinusoidal waveform with harmonic modulation. The output voltage 24 is specified by the control and / or regulating unit 20 in such a way that a harmonic coil current 28 flowing during operation in addition to a fundamental coil current is set to a value determined in a calibration step 30.The harmonic coil current 28 is set by adapting the output voltage 24 to the harmonic coil voltage 32 induced by the permanent magnets 16. The harmonic coil current 28 is eliminated by setting the value determined in the calibration step 30 to zero. The harmonic coil current 28 is eliminated by specifying the output voltage 24 such that the harmonic differential voltage 42 is zero. It is conceivable for the control and / or regulating unit 20 to have a plurality of value tables 46. In this case, a value table 46 is assigned to one of several different operating states. This could predetermine the relationship between the output voltage 24 and the angle of rotation 22 of the electric motor 10 depending on an operating parameter. During operation, a value table 46 could be selected depending on the operating parameters.Alternatively, the control and / or regulation unit 20 could have a set of algebraic functions 48. An algebraic function 48 could be assigned to one of the various operating states. During operation, a value table 46 could be selected depending on the operating parameters.

[0033] In a further method step 64, the output voltage signal 44 is supplied to the electronic circuit 34. The output voltage 24 is generated by the electronic circuit 34. A three-phase alternating current is generated by the electronic circuit 34. The three-phase alternating current is generated with a harmonic-modulated sine waveform.

[0034] In a further method step 66, the rotor 18 is driven by the output voltage 24 applied to the coils 12. During operation, the rotor 18 is rotated relative to the stator 14.

[0035] Figure 5 shows a schematic flow diagram of a calibration process for determining parameters for the control method. In the calibration process, the value table 46 of the electric motor 10 is determined. Alternatively, the algebraic function 48 is determined during the calibration of the electric motor 10.

[0036] In a sub-step 68 of the calibration step 30, a value for the harmonic coil current 28 superimposed on the fundamental oscillation coil current is determined. The operation of the electric motor 10 is optimized using the value of the harmonic coil current 28. The calibration step 30 is carried out individually for each electric motor 10. Alternatively, it is conceivable that the calibration step 30 is carried out once for each type of electric motor 10 and the determined value is then applied to each electric motor 10 of the same type. Alternatively, it is conceivable that the sub-step 68 of the calibration step 30 is carried out for a plurality of identical electric motors 10 and the determined value is applied as an average value to all electric motors 10. Alternatively, the value / averaged value could be re-determined at regular intervals and applied to the electric motors 10.Alternatively, it is also conceivable that the value / averaged value is determined for each production line / batch, etc. Furthermore, it is conceivable that calibration step 30 is performed after maintenance / inspection and / or at regular intervals.

[0037] In a further sub-step 70 of calibration step 30, the output voltages 24 are determined at which the electric motor 10 is operated with the value of the harmonic coil current 28. The output voltages 24 determined in the further sub-step 70 are implemented in the control and / or regulating unit 20 as a value table 46 or as an algebraic function 48. It is conceivable that output voltages 24 are determined for various operating parameters. The value tables 46 determined in this process or the family of algebraic functions 48 determined in this process with the output voltages 24 dependent on the rotation angle 22 of the rotor 18 are implemented in the control and / or regulating unit 20.

Claims

Claims 1. Control method for an electric motor (10), in particular a brushless DC electric motor, preferably a permanent magnet synchronous motor, with a stator (14) having at least one coil (12) and with a rotor (18) having at least one permanent magnet (16) which is rotated relative to the stator (14) during operation, and with at least one control and / or regulating unit (20), in particular a microprocessor, with which an output voltage (24) for driving the rotor (18) is predetermined as a function of an angle of rotation (22) of the rotor (18) to the stator (14), characterized in that the output voltage (24) is predetermined in such a way that a harmonic coil current (28) flowing during operation, in particular in addition to a fundamental oscillation coil current, is set at least substantially to a value determined in at least one calibration step (30).

2. Control method according to claim 1, characterized in that the harmonic coil current (28) is at least substantially eliminated by setting the value determined in the calibration step (30) to zero.

3. Control method according to one of the preceding claims, characterized in that the harmonic coil current (28) is adjusted by adapting the output voltage (24) to the coil voltage (32) induced by the at least one permanent magnet (16).

4. Control method according to one of the preceding claims, characterized in that a relationship between the output voltage (24) and the angle of rotation (22) of the rotor (18) to the stator (14) is described via a sinusoidal curve with a harmonic modulation, which takes into account at least one harmonic oscillation of the coil voltage (32) induced by the at least one permanent magnet (16).

5. Control method according to one of the preceding claims, characterized in that the output voltage (24) is stored in the control and / or regulating unit (20) on the basis of a value table (46), preferably determined during calibration of the electric motor (10).

6. Control method according to one of claims 1 to 4, characterized in that the output voltage (24) is stored in the control and / or regulating unit (20) as an algebraic function (48), preferably determined during calibration of the electric motor (10).

7. Control method according to one of the preceding claims, characterized in that the relationship between the output voltage (24) and the angle of rotation (22) of the electric motor (10) is predetermined as a function of at least one operating parameter, in particular engine load, engine speed, engine temperature and / or operating voltage.

8. Control method according to claim 7, characterized in that a plurality of value tables (46) or a set of algebraic functions (48) are assigned to different operating states, which are selected in the operation depending on the operating parameters.

9. Calibration method for determining parameters, in particular for the control method according to one of the preceding claims, characterized in that the calibration step (30) is carried out, preferably individually, for each electric motor (10).

10. Electric motor (10) with a control method according to one of the preceding claims.

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