A method for determining a back electromotive force of an electric engine of a motor vehicle by an electronic computing device, a corresponding computer program product, as well as a corresponding electronic computing device

Abstract

The present invention relates to a method for determining a back electromotive force (34) of an electric engine (14) of a motor vehicle (10) by an electronic computing device (16), comprising the steps of: determining a battery voltage (vdc) of a battery (12), a phase voltage (vu, vv, vw), and a phase pole voltage (vun, vvn, vwn) of the electric engine (14);- determining a voltage value (um, vm, wm) of a power device (22, 24, 26, 28, 30, 32) of the electric engine (14) depending on the battery voltage (vdc), the phase voltage (vu, vv, vw), and the phase pole voltage (Vun, Vvn, Vwn); and determining the back electromotive force (34) depending on the voltage value (Um, Vm, Wm).

Description

Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 1 Mercedes-Benz Group AG Felton 18.10.2023 A METHOD FOR DETERMINING A BACK ELECTROMOTIVE FORCE OF AN ELECTRIC ENGINE OF A MOTOR VEHICLE BY AN ELECTRONIC COMPUTING DEVICE, A CORRESPONDING COMPUTER PROGRAM PRODUCT, A CORRESPONDING NON-TRANSITORY COMPUTER-READABLE STORAGE MEDIUM, AS WELL AS A CORRESPONDING ELECTRONIC COMPUTING DEVICE ^^ FIELD OF THE INVENTION ^^^

[0001] The present invention relates to a field of automobiles. More specifically, the^ present invention relates to a method for determining a back electromotive force of an^^ electric engine of a motor vehicle by an electronic computing device. Furthermore, the^ present invention relates to a corresponding computer program product, a corresponding ^ ^ non-transitory computer-readable storage medium, as well as to a corresponding ^ electronic computing device. ^^^ BACKGROUND INFORMATION

[0002] So called axial flux electric engine comprises the highest power intensity within the electric engines and high sufficiency at operating range of a motor vehicle. Because of those reason it is essential to provide an efficient control of that axial motor.

[0003] Rotor flux (^^) is varied -10% and +10% with the magnetic temperature. The rotor flux information is important to achieve high accuracy torque control and high efficiency operation. Rotor flux, according the state of the art, may be measured by back electromotive force based method. Normally, according to the state of the art, current methods needs two or three phase lines to neutral, which needs a 2,3 high voltage divided circuit and 2,3 isolated amplifier to measure high voltage line voltage or line to neutral. Therefore, current methods need high voltage circuits.Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 2 SUMMARY OF THE INVENTION

[0004] It is an object of the invention to provide a method, a corresponding computer program product, a corresponding non-transitory computer-readable storage medium, as well as a corresponding electronic computing device, by which a back electromotive force can be measured in a simple way.

[0005] This object is solved by a method, a corresponding computer program product, a corresponding non-transitory computer-readable storage medium, as well as a corresponding electronic computing device.

[0006] One aspect of the invention relates to a method for determining a back electromotive force of an electric engine of a motor vehicle by an electronic computing device. A battery voltage of a battery of the motor vehicle is determined. A phase voltage of the motor vehicle is determined. A phase pole voltage may be determined. The voltage value depending on a battery voltage, the phase voltage, and / or the phase pole voltage of a power device of an engine controller of the electric engine is determined. The back electromotive force is determined depending on the voltage value. For example, the voltage value may be the difference between the battery voltage and the phase voltage.

[0007] Therefore, a back electromotive force measurement method with voltage value depending on the battery voltage, which may also be a so-called direct current (DC) link voltage, the phase voltage, and / or the phase pole voltage is provided. This corresponding electric circuit for a measurement is simpler than the voltage circuit according to the state of the art.

[0008] Therefore, the electronic computing device can be implemented with less effort and does not need an isolated amplifier.

[0009] According to an embodiment depending on determined back electromotive force a rotor flux of the electric engine is determined. In particular, the back electromotive force is depending on the rotor flux. Therefore, by measuring the back electromotive force the rotor flux can be measured. Therefore, a way for measuring of the rotor flux is provided.

[0010] Another embodiment a torque of the electric engine is controlled depending on the determined rotor flux. In particular, the torque is controlled depending on the rotor flux. In particular according to the following equation:Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 3

[0011] The torque can be controlled. Therefore, the inefficiency of the electric engine may be reduced or eliminated.

[0012] In another embodiment an analogue digital converter and a gate driver integrated circuit (IC) is used for determining the back electromotive force. In particular, the analogue digital converter can be aligned with a digital command. Therefore, the analog digital converter (ADC)-conversion may be aligned with digital command to reduce the noise from the switching of the power device and / or gate driver IC.

[0013] In another embodiment, a phase voltage or a phase pole voltage of a high side power device is captured. In particular, the control circuit or engine controller comprises for each phase a high side device as well as a low side device. The high side device is connected to a positive pole of the battery (dc+) and the low side power device is connected to the negative pole of the battery (dc-). Therefore, a way for determining the phase voltage and phase pole voltage is provided.

[0014] In another embodiment a phase voltage or the phase pole voltage of a low side power device is captured. In particular, the control circuit comprises for each phase a high side device as well as a low side device. The high side device is connected to a positive pole of the battery (dc+) and the low side power device is connected to the negative pole of the battery (dc-). Therefore, a way for determining the phase voltage and phase pole voltage is provided.

[0015] In another embodiment, a phase voltage and a phase pole voltage of a low side power device and / or high side power device is captured. In particular, the control circuit comprises for each phase a high side device or a low side device. The high side device is connected to a positive pole of the battery (dc+) and the low side power device is connected to the negative pole of the battery (dc-). Therefore, a way for determining the phase voltage and phase pole voltage is provided.

[0016] In another embodiment phase voltages and phase pole voltages of three phases of the engine control circuit are captured and depending on the battery voltage, the phase voltages, and the phase pole voltages, the back electromotive force is determined. In particular, the three phase pole voltages vun, vvn, vwn of the three phases u, v, w areApplicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 4 captured and used for determining the back electromotive force. Therefore, a simple way for determining the back electromotive force is provided.

[0017] In particular the method is a computer-implemented method. Therefore, another aspect of the invention relates to a computer program product comprising program code means for performing a method according to the preceding aspect.

[0018] A still further aspect of the invention relates to a non-transitory computer- readable storage medium comprising at least the computer program product according to the preceding aspect.

[0019] Furthermore, the present invention relates to an electronic computing device for determining a back electromotive force of an electric engine of a motor vehicle, wherein the electronic computing device is configured for performing a method according to the preceding aspect. In particular, the method is performed by the electronic computing device.

[0020] Furthermore, the invention relates to an electric engine comprising at least the electronic computing device according to the preceding aspect.

[0021] Furthermore, the invention relates to a motor vehicle comprising at least the electric engine according to the preceding aspect. For example, the motor vehicle may be configured as an at least in part electrically operated motor vehicle or a fully electrically operated motor vehicle.

[0022] A computing unit / electronic computing device may, in particular, be understood as a data processing device, which comprises processing circuitry. The computing unit can therefore in particular process data to perform computing operations. This may also include operations to perform indexed accesses to a data structure, for example a look-up table, LUT.

[0023] In particular, the computing unit may include one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits, ASIC, one or more field-programmable gate arrays, FPGA, and / or one or more systems on a chip, SoC. The computing unit may also include one or more processors, for example one or more microprocessors, one or more central processing units, CPU, one or more graphics processing units, GPU, and / or one or moreApplicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 5 signal processors, in particular one or more digital signal processors, DSP. The computing unit may also include a physical or a virtual cluster of computers or other of said units.

[0024] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more memory units.

[0025] A memory unit may be implemented as a volatile data memory, for example a dynamic random access memory, DRAM, or a static random access memory, SRAM, or as a non-volatile data memory, for example a read-only memory, ROM, a programmable read-only memory, PROM, an erasable programmable read-only memory, EPROM, an electrically erasable programmable read-only memory, EEPROM, a flash memory or flash EEPROM, a ferroelectric random access memory, FRAM, a magnetoresistive random access memory, MRAM, or a phase-change random access memory, PCRAM.

[0026] Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and / or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The novel features and characteristic of the disclosure are set forth in the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and together with the description, serve to explain the disclosed principles. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and / or methods in accordance with embodiments of the present subject matter are now described below, by way of example only, and with reference to the accompanying figures. The drawings show in:Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 6

[0028] Fig.1 a schematic side view according to an embodiment of a motor vehicle comprising an embodiment of an electric engine comprising in an embodiment of an electronic computing device;

[0029] Fig.2 a schematic block diagram according to an embodiment of an electric engine;

[0030] Fig.3 a schematic block diagram according to an embodiment of a powertrain;

[0031] Fig.4 another schematic block diagram according to an embodiment of the powertrain; and

[0032] Fig.5 is a flow chart according to an embodiment of the present invention.

[0033] In the figures the same elements or elements having the same function are indicated by the same reference signs. DETAILED DESCRIPTION

[0034] In the present document, the word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment or implementation of the present subject matter described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0035] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawing and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0036] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion so that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus preceded by “comprises” or “comprise” does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or method.Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 7

[0037] In the following detailed description of the embodiment of the disclosure, reference is made to the accompanying drawing that forms part hereof, and in which is shown by way of illustration a specific embodiment in which the disclosure may be practiced. This embodiment is described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0038] Fig.1 shows a schematic side view of a motor vehicle 10. The motor vehicle 10 is at least in part electrically operated or fully electrically operated. The motor vehicle 10 therefore comprises a battery 12 for providing electric energy for an electric engine 14. Furthermore, the electric engine 14 may be controlled by an electronic computing device 16. In some embodiments, the electronic computing device 16 may be part of a powertrain 60 (Fig.3) as shown in Figs.3 and 4 or an external component of the powertrain 60.

[0039] Fig.2 shows a schematic block diagram according to an embodiment of the electric engine 14 with a control circuit 18 for controlling the electric engine 14. The control circuit 18 may be configured for controlling the electric engine 14. The electric engine 14 may include electrical components such as an inductor L and resistor R. Therefore, the controlled circuit 18 may comprise an inverter device 20. The inverter device 20 for example comprises six power devices 22, 24, 26, 28, 30, 32. In particular, each phase u, v, w comprises two power devices 22, 24, 26, 28, 30, 32. For example, a first phase u comprises a first power device 22 and a fourth power device 28. The second phase v comprises a second power device 24 an a fifth power device 30. The third phase w comprises a third power device 26 a sixth power device 32.

[0040] The power device 22, 24, 26 are so called high side 52 power devices and the power devices 28, 30, 32 are so called low side 54 power devices. The high side 52 power devices 28, 30, 32 are connected to dc+, and the low side 54 power devices are connected to dc-. There is also ground N and the phase pole voltages vun, vvn, and vwn may be captured by measuring between the ground N and each phase voltage u, v, w.

[0041] In particular as shown, the power devices 22, 24, 26, 28, 30, 32 are configured as so called IGBT and also implemented SiC. Because of operating efficiency and physical behaviors, both power device are good for high voltage and high power HEV and EV application. An insulated-gate bipolar transistor (IGBT) is a three-terminal powerApplicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 8 semiconductor device primarily forming an electronic switch. It consists of four alternating layers (P–N–P–N) that are controlled by a metal–oxide–semiconductor (MOS) gate structure. Furthermore, each of the power devices 22, 24, 26, 28, 30, 32 comprises a blocking diode.

[0042] For determining the back electromagnetic force with the present invention, the rotational de-qe reference frame voltage equation for an axial flux electric engine 14 can be expressed as:

[0043] Furthermore, the rotational de-qe reference frame voltage equation of axial flux electric engine 14 can be expressed as: ^^^^=^^^^= 0 (if all phase currents are zero) ^^^^= 0

[0044] The stationary ds-qs reference frame voltage equation for the axial flux electric engine 14 and back electromotive force 34 (shown in Figs.3 and 4) can be expressed as:BackEMF = ^^× ^^(dependent on stationary dq voltage)

[0045] With the present disclosure, the stationary dq voltage and back electromotive force 34 based on the voltage value Um, Vm, Wm (as shown in Figs.3 and 4) may be determined. The voltage value Um, Vm, Wm may be determining using the battery voltage vDC, the phase voltage Vu, Vv, Vw, and / or the phase pole voltage Vun, Vvn, Vwn.Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 9

[0046] Fig.3 shows another schematic block diagram according to an embodiment of the invention with a powertrain 60. In particular, it is shown, that for determining a back electromotive force 34 of the electric engine 14. The battery voltage vDC of the battery 12 may be captured by the electronic computing device 16. A phase voltage Vu, Vv, Vw, and a phase pole voltage Vun, Vvn, Vwn of a power device 22, 24, 26, 28, 30, 32 of an engine controller, in particular the inverter 20, of the electric engine 14 may be captured by the electronic computing device 16. The back electromotive force 34 is determined depending on a voltage value Um, Vm, Wm. The voltage value Um, Vm, Wm may depend on the battery voltage vdc, the phase voltage Vu, Vv, Vw, and / or the phase pole voltage Vun, Vvn, Vwn. Additionally, a rotor flux 36 of the electric engine 14 is determined depending on the determined back electromotive force 34. Furthermore, a torque 38 for controlling the electric engine 4 may be determined based on the rotor flux 36. Furthermore, a supply 56 is shown.

[0047] As shown in Fig.3, the voltage value Um, Vm, Wm depending on the battery voltage vDC of the battery 12 and the phase voltage Vu, Vv, Vw, of a high side 52 power device 22, 24, 26 is captured. Furthermore, it is shown, that a gate driver 40, 42, 44, 46, 48, 50 is used for determining the back electromotive force 34. The control circuit 18 may include the inverter 20, a gate driver board, a microprocessor, and other components. In particular, for the first phase voltage vu, the first power device 22, a first gate driver 40, and fourth gate driver 46 are used along with a digital command from the microprocessor and / or electronic computing device 16. For the second phase voltage vv, the second power device 24, a second gate driver 42 and fifth gate drive 48 are used. Furthermore, for the third phase voltage vw, the third power device 26, a third gate driver 44 and sixth gate driver 50 may be used.

[0048] As shown in Fig.3, digital command signals from the electronic computing device 16, microprocessor, and / or the gate drivers 40, 42, 44, 46, 48, 50 are aligned with digital command signal to reduce noise from the switching of the power devices, in particular the power devices 22, 24, 26, 28, 30 and 32. For example, the digital command signal from the microprocessor may trigger a conversion of the voltage value Um, Vm, Wm depending on the phase voltage Vu, Vv, Vw or the phase pole voltage Vun, Vvn, Vwn values from the gate drivers 40, 42, 44, and the DC link voltage or voltage vdc from the battery 12.

[0049] The determination for the voltage value Um, Vm, Wm may be based on the battery voltage vdc and the phase voltage Vu, Vv, Vw. In some embodiments, theApplicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 10 determination for the voltage value Um, Vm, Wm may be based on the battery voltage vdc such as the DC link voltage and the phase voltage Vu, Vv, Vw or the phase pole voltage Vun, Vvn, Vwn may be also based on the high side 52 power devices 22, 24, 26 and may be expressed as: ^^= ^^^^− ^^= (^^^^− ^^^^) − (^^− ^^^^) = ^^^−(^^− ^^^^^−^^^^ +^^^^ ) ^ = ^^^^^− ^^^–− 2

[0050] Fig.4 shows another embodiment according to the invention with the powertrain 60. The control circuit 18 may include the inverter 20, a gate driver board, a microprocessor, and other components to determine the voltage value um, vm, wm. In Fig.4, it is shown, that the low side 54 power devices 28, 30, 32 are used for capturing the phase voltage Vu, Vv, Vw. For the first phase voltage vu, the fourth power device 28, the first gate driver 40, and the fourth gate driver 46 is used. For the second phase voltage vv, the fifth power device 30, the second gate driver 42, and the fifth gate driver 48 is used, and for the third phase voltage vw, the sixth power device 32, the third gate driver 44, and the sixth gate driver 50 is used.

[0051] In another embodiment, the determination for the voltage value Um, Vm, Wm based on the battery voltage vdc and the phase voltage Vu, Vv, Vw or the phase pole voltage Vun, Vvn, Vwn may be based on the low side 54 power devices 28, 30, 32 and may be expressed as:^^^^^^ ^ = ^ − , ^ =^ ^^^^ ^^ − , ^ = ^ − 2^^ ^2^^ ^2Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 11

[0052] With the present disclosure, in addition to determining the stationary dq voltage and back electromotive force 34 based on the voltage value Um, Vm, Wm, the rotor flux 36 and torque 38 may be determined as shown below:

[0053] The stationary ds-qs reference frame dq voltage equation and back electromotive force 34 equation for determining the rotor flux 36 for the axial flux electric engine 14 can be expressed as:BackEMF = ^^× ^^(calculated with stationary ds-qs reference frame dq voltage)

[0054] In certain embodiments, the electronic computing device 16 may determine that the battery voltage VDC is greater than the back electromotive force 34. When the battery voltage VDC is greater than the back electromotive force 34, the electronic computing device 16 may set all switches open and send PWM signals to the microprocessor or IC of the gate drivers 40, 42, 44, 46, 48, 49, 50. The microprocessor coupled to the electronic computing device 16 may trigger all the analog digital converters of high side 52 gate drivers 40,42,44 , all the analog digital converters of low side 54 gate drivers 46, 48 and 50, or the analog digital converter of another gate driver, which may be assigned to detect and measure the voltage value Um, Vm, Wm based on the phase voltage Vu, Vv, Vw, the phase pole voltage Vun, Vvn, Vwn, and / or the battery voltage vdc of battery 12.

[0055] For example, in the so-called idle condition of the inverter 20, all switches open and all phase currents are zero. Under this condition, the high side 52 gate driver 40, 42,Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 12 44 and low side 54 gate driver 46, 48, 50 may be used to determine the voltage value Um, Vm, Wm depending on the battery 12 and other captured voltages such as the phase voltage Vu, Vv, Vw or the phase pole voltage Vun, Vvn, Vwm.

[0056] In some embodiments, the analog digital converter may be an internal or external component with a voltage isolator of the gate drivers 40, 42, 44, 46, 48, 50. The conversion of the PWM signals to and / or from the gate drivers 40, 42, 44, 46, 48, 50 may be aligned with the digital command signal to reduce noise from the switching of the power devices 22, 24, 26, 28, 30, 32.

[0057] Fig.5 shows a flow chart of a method according to an embodiment of the invention. The method is to determine the back electromotive force 34 of the electric engine 14. At a first step S1, the battery voltage vdc of the battery 12 the phase voltage vu, vv, vw, and the phase pole voltage Vun, Vvn, Vwm may be determined. For example, the electronic computing device 16 may detect or capture the battery voltage vdc and the phase voltage vu, vv, vw. For a second step S2, the voltage value um, vm, wm of the power devices 22, 24, 26, 28, 30, 32 of the electric engine 14 may be determined based on the battery voltage vdc and at least one of the phase voltage Vu, Vv, Vw or the phase pole voltage vun, vvn, vwn. For example, the voltage value Um, Vm, Wm may be determined using a particular polarity or a portion of the battery voltage (vdc) and the phase voltage Vu, Vv, Vw or the phase pole voltage Vun, Vvn, Vwm as shown in the expressions above. At a third step S3, the back electromotive force 34 may be determined based on the voltage value um, vm, wm.

[0058] In some embodiments, the electronic computing device 16 such as a motor controller or electronic drive unit (EDU) may implement steps S1, S2, and S3.

[0059] In another embodiment, the method may include steps for the ADC to signal the determination for the voltage value um, vm, wm. Then, the electronic computing device 16 may determine the voltage value Um, Vm, Wm based on the battery voltage VDC, the phase voltage Vu, Vv, Vw, and / or phase pole voltage Vun, Vvn, Vwn.Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 13 Reference List 10 motor vehicle 12 battery 14 electric engine 16 electronic computing device 18 control circuit 20 inverter 22 first power device 24 second power device 26 third power device 28 forth power device 30 fifth power device 32 sixth power device 34 back electromotive force 36 rotor flux 38 torque 40 first gate driver 42 second gate driver 44 third gate driver 46 fourth gate driver 48 fifth gate driver 50 sixth gate driver 52 high-side 54 low side 56 supply 60 powertrain VDC, vdc battery voltage Vu, Vv, Vw, u, v, w phase voltage Um, Vm, Wm, um, vm, wm voltage value Vun, Vvn, Vwn, vun, vvn, vwn phase pole voltage N, n ground L inductor R resistor S1-S3 steps of method

Claims

Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 14 Mercedes-Benz Group AG Felton 18.10.2023 CLAIMS 1. A method for determining a back electromotive force (34) of an electric engine (14) of a motor vehicle (10) by an electronic computing device (16), comprising the steps of: - determining a battery voltage (vdc) of a battery (12), a phase voltage (vu, vv, vw), and a phase pole voltage (vun, vvn, vwn) of the electric engine (14); - determining a voltage value (um, vm, wm) of a power device (22, 24, 26, 28, 30, 32) of the electric engine (14) depending on the battery voltage (vdc), the phase voltage (vu, vv, vw), and the phase pole voltage (vun, vvn, vwn); and - determining the back electromotive force (34) depending on the voltage value (Um, Vm, Wm).

2. The method according to claim 1, characterized in that depending on the determined back electromotive force (34) a rotor flux (36) of the electric engine (14) is determined.

3. The method according to claim 2, characterized in that a torque (38) of the electric engine (14) is controlled depending on the determined rotor flux (36).

4. The method according to any one of claims 1 to 3, characterized in that a microprocessor of a gate driver (40, 42, 44, 46, 48, 50) is used for determining the back electromotive force (34).Applicant’s Ref.: 2023P00278WO Attorney’s Ref.: 89713 15 5. The method according to any one of claims 1 to 4, characterized in that the voltage value (um, vm, wm) of a high side (52) power device (22, 24, 26) is captured.

6. The method according to any one of claims 1 to 4, characterized in that the voltage value (um, vm, wm) of a low side (54) power device (28, 30, 32) is captured.

7. A computer program product comprising program code means for performing a method according to any one of claims 1 to 6.

8. An electronic computing device (16) for determining a back electromotive force (34) of an electric engine (14) of a motor vehicle (10), wherein the electronic computing device (16) is configured for performing a method according to any one of claims 1 to 6.

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