Method and device for controlling an electric machine, and electric drive system

Abstract

The invention relates to a method for controlling an electric machine (4) comprising a stator with a stator winding and comprising a rotor. In the method, the electric machine (4) is controlled (200) using a voltage manipulated variable (32) such that a current flows through the electric machine (4) which satisfies a torque demand on the electric machine (4) and such that a disturbance of a specified amplitude and a specified frequency is impressed on the current. A current (42) flowing through the stator windings and an acceleration signal (41) are detected (210). Subsequently, response parameters (51) representing the response characteristic between the detected current (42) and the detected acceleration signal (41) are determined (220) on the basis of the detected current (42) and the detected acceleration signal (41). The electric machine (4) is then controlled (230) using the determined response parameters (51).

Description

Description title Method and device for controlling an electric machine and electric drive system The present invention relates to a method and a device for controlling an electric machine, as well as an electric drive system and a computer program for carrying out the method. Background of the invention Due to their design characteristics or in the event of faults, electric drive systems comprising an electric motor and power electronics do not exhibit smooth torques, but rather torques containing harmonics. Radial force excitations also occur at the rotor of the electric motor. Rotating field machines, such as squirrel-cage induction motors (ACMs) or permanent magnet synchronous motors (PMSMs), do not possess ideal sinusoidal flux distributions in the air gap due to their design. During operation, this leads to non-uniform torques containing harmonics when controlled with sinusoidal currents. In addition to the resulting torsional vibrations in the drive train, these non-uniformities also cause radial force excitations between the stator and rotor, which manifest directly as housing vibrations and consequently as noise, vibration, and harshness (NVH). If the electric machine drives an uneven load, for example a compressor for a heat pump, additional [effects] result. Harmonic vibrations are present at the rotational speed of the electric machine's rotor. These harmonic vibrations, torque curves, and radial force excitations superimpose, leading to housing vibrations and thus to sound radiation. The problem is exacerbated in particular by external oscillating load moments, such as those caused by a compressor installed in a heat pump. Overall, the design characteristics of the electric drive system can therefore sometimes cause undesirable, noticeable vibrations in the drive train, in the electrical network and / or acoustically perceptible noise emissions. Electric rotating field machines are usually controlled by field-oriented control (FOC). This control system is essentially designed to regulate the fundamental frequency of the voltage and current, whereby the fundamental voltage frequency is converted into its equal-sized components using the d / q transform. d ,u q and the fundamental wave of the current into the equal sizes i d , i q They are transformed in the co-rotating d / q coordinate system. The variables of equal magnitude are controlled in this coordinate system, and the determined control variables u are calculated. d ,u q It is then transformed back into the time domain and used as the fundamental frequency of the voltage to control the electric machine. This method does not allow for the influencing or reducing of harmonics. Several approaches are possible for minimizing harmonics. One possibility is the targeted application of exogenous disturbance compensation, which leads to insufficient performance in real-world operation if operating-dependent parameters (such as temperature-dependent parameters) or manufacturing tolerances are present. Advanced methods for imprinting current harmonics via input voltages can indeed remove harmonics from the drive train, but require higher-level knowledge about the amplitude and phase of the Interference oscillation or a higher-level search procedure with a slow transient process. German patent application DE 10 2023 207 191 A1 discloses a control system for the cancellation or targeted reduction of harmonic overtones. Furthermore, it discloses an adaptive real-time control system without pre-setting the optimal currents. To implement this method, transmission parameters for an unknown system are required or are adaptively estimated. The content of this application is incorporated herein by reference. Disclosure of the invention According to the invention, a method and a device for controlling an electric machine, as well as an electric drive system and a computer program for carrying out the method, are proposed, comprising the features of the independent claims. Advantageous embodiments are the subject of the dependent claims and the following description. The invention relates to an electric machine with a stator and a rotor winding. The electric machine can, for example, be controlled or powered by a device according to the invention, which can also be called an inverter. For this purpose, voltage waveforms are specified to the inverter or device, which are to be applied to the stator winding by the inverter. These voltage waveforms can be adapted in such a way that harmonics, as described above, are reduced or eliminated. To determine the adaptation of the voltage waveforms, transfer parameters are required that relate a current flowing through the stator windings to a measured acceleration signal, which, for example, measures vibrations in the electric machine. The invention optimizes the determination of transmission parameters by actively exciting a disturbance that leads to noise generation. For this purpose, a voltage is applied to the electrical machine, through which A current flows through the electric machine, fulfilling the torque requirement of the electric machine, and a current disturbance with a predetermined amplitude and frequency is applied to it. The invention enables, in particular, the direct manipulation of harmonic-containing acceleration signals in an electric drive system without requiring any higher-level knowledge. The only prerequisites are the measurability of these signals (e.g., via inexpensive MEMS sensors (microelectromechanical systems)) and a physical relationship to the current parameters of the electric drive (e.g., current - torque). This relationship is determined simply and with minimal computational effort by the method according to the invention. The invention enables a fast and robust estimation of the unknown transmission parameters that are necessary for imprinting the optimal current harmonics to reduce or cancel out the noise-generating harmonics according to, for example, the method from DE 10 2023 207 191 A1. This continues to enable optimal control without manual process effort, such as determining parameters for different applications at the factory. The invention can also be used during the design process of electrical machines to, for example, manufacture them more cost-effectively. This enables designs that would otherwise be unfeasible due to high torque ripple or noise issues. It also expands the scope for optimizing the electrical machine, as optimization options previously excluded due to noise concerns can now be considered again. Furthermore, the introduction of current harmonics can generally increase operational comfort, as, for example, the vibrations are reduced. The generated noise emission is reduced. In particular, determining the transmission parameters in conjunction with harmonic control allows convenient access to influencing the noise profile of an electric machine even at a late project stage by simply adjusting the data, which is especially advantageous in the case of noise problems that often only manifest themselves in the final installation situation. Advantageously, the invention also extends the service life of the electric machine and its surrounding components by reducing vibration stress. In particular, the invention enables optimal operation despite aging or interference effects over the machine's service life, as these effects can be compensated for by the method. Advantageously, the invention is suitable for multi-variable systems with several manipulated and controlled variables, such as electric rotating field drive systems with a synchronous machine with the two input voltages and the two measured variables, and can therefore be used in a large number of existing systems. Furthermore, the method provides an adaptive estimation of the existing physical relationship with the current quantities, independent of the position of the sensor in the drive system, which characterizes the modularity of this method. In the inventive method for controlling an electric machine comprising a stator with a stator winding and a rotor, the electric machine is controlled by a voltage control variable, causing a current to flow in the stator winding of the electric machine. This current fulfills a torque requirement for the electric machine and is subjected to a current disturbance with a predetermined amplitude and frequency. During this process, the current flowing through the stator windings and an acceleration signal are detected. The acceleration signal is detected, in particular, by a MEMS sensor. Depending on the detected current and the detected acceleration signal, transmission parameters are determined that represent the transmission behavior between the detected current and the detected acceleration signal. These transmission parameters include, for example, a real part and an imaginary part of a transmission matrix that maps the transmission of a current through the stator winding of the electric machine to the acceleration signal, and an offset disturbance. Subsequently, the electric machine is controlled using the determined transmission parameters. This control can be carried out, for example, using a method as described in the aforementioned DE 10 2023 207 191 A1, in particular paragraphs

[0073] until

[0079] , revealed, carried out. With steady-state excitation, i.e., without active excitation of the current disturbance, the transmission parameters cannot be accurately determined because only two equations are available for four unknown parameters, resulting in an infinite number of possible solutions. The noise generated by the applied current disturbance allows the transmission parameters to be determined more precisely without any prior knowledge. The procedure is carried out primarily during operation, whereby the control with a voltage control variable, which causes a current with an imposed current disturbance to flow through the stator windings of the electric machine, is only performed for a short period, for example, 5 to 10 seconds. Furthermore, the procedure can be carried out repeatedly, with an intervening phase of normal operation. The procedure can also be repeated for different predetermined amplitudes and / or frequencies. The electrical disturbance with a given amplitude and frequency can, for example, have a sinusoidal or rectangular shape. To introduce current disturbances in a field-oriented control system used to determine the voltage control variable, a current with a specified amplitude and frequency can be added to the set current. For a rectangular waveform, the frequency can be alternately adjusted. During specific time periods, a current value with a predetermined amplitude is added or subtracted. Due to the transient behavior of the field-oriented control, this results in a sinusoidal waveform of the current disturbance. The invention makes it possible to determine transmission parameters for reducing or eliminating harmonics responsible for noise or vibrations of the electric machine in a simple manner and with low computational effort, with improved accuracy, thereby achieving the aforementioned advantages. In one embodiment, the predetermined amplitude of the current disturbance is specified as a function of the acceleration signal. The higher the excitation, i.e., the greater the amplitude of the current disturbance, the better the parameters can be estimated. However, a larger amplitude also leads to increased noise. Therefore, a compromise must be made between the lowest possible amplitude to avoid noise and a sufficiently large amplitude to allow for accurate estimation of the transmission parameters. In one embodiment of the method, the transmission parameters are estimated using an Information Matrix Decomposition Least Squares (IMDLS) method. The procedure for this method is described, for example, in DE 10 2023 207 191 A1, in particular paragraphs

[0052] until

[0057] , revealed. Alternatively, a gradient-based estimation method or another suitable estimation method can be used. By using a suitable estimation method, the transmission parameters can be determined easily and with minimal computational effort. In one embodiment, the determination of the transmission parameters continues to depend on a harmonic frequency of the The acceleration signal, which depends in particular on the electrical angular frequency of the electric machine, is used. The harmonic frequency is, for example, an integer multiple of the electrical angular frequency of the electric machine and can be measured or determined from the control signal of the electric machine. This makes it possible to use the specific transmission parameters for noise reduction even during normal operation of the electric machine. In one embodiment, during the control of the electric machine with the voltage control variable, a noise reduction method, which is implemented in particular by harmonic control of the electric machine and which counteracts disturbances on the acceleration signal and the current flowing through the stator winding of the electric machine, is carried out with a reduced effect or stopped entirely. Conventionally, the setpoints for the control of the electric machine are determined in such a way as to achieve minimal noise generation, which, however, could also reduce the deliberately imposed current disturbance. Therefore, such noise reduction methods are expediently interrupted or at least reduced in their effect during the implementation of the invention. As a result, the harmonic control does not attempt to...to a lesser extent, reducing the imposed disturbance, thereby improving the estimation of the transmission parameters. The device according to the invention for controlling the electric machine comprises a power converter circuit which is configured to be coupled to the stator of the electric machine and to provide an electrical voltage for controlling the stator of the electric machine, and a computing unit, e.g. a logic circuit, integrated circuit or microcontroller which is configured, in particular in terms of programming, to carry out a method according to the invention. The electrical drive system according to the invention comprises a device according to the invention and an electric machine, wherein the electric machine is electrically coupled to the converter circuit of the device. Implementing a method according to the invention in the form of a computer program or computer program product with program code for carrying out all method steps is also advantageous, as this incurs particularly low costs, especially if an executing computing unit is already available for other tasks. Finally, a machine-readable storage medium is provided with a computer program stored on it as described above. Suitable storage media or data carriers for providing the computer program are, in particular, magnetic, optical, and electrical storage devices, such as hard drives, flash memory, EEPROMs, DVDs, etc. Downloading a program via computer networks (Internet, intranet, etc.) is also possible. Such a download can be wired or wireless (e.g., via a WLAN network, a 3G, 4G, 5G, or 6G connection, etc.). Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing. To better illustrate the relationships, example equations are used below. Quantities with the subscript "dq" are vectors where the first component corresponds to the d-component and the second component to the q-component of the respective quantity in the d / q coordinate system. Quantities with only one subscript "d" or "q" denote the respective component of the quantity in the d / q coordinate system. Furthermore, the subscript "y" denotes the acceleration signal, the subscript "i" the current, and the subscript "u" the voltage. The calculation of the quantities is shown according to the sine component (subscript "s") and cosine component (subscript "c") of the various quantities. However, this can easily be extended to the real and imaginary parts or the amplitude and phase components. The following equation can be used for a transfer matrix that maps the transfer of a current through the stator winding of the electric machine to the acceleration signal: with j = the acceleration signal components 0 y , the transfer matrix G MEMS , the harmonic frequency d , the model matrix of the permanent magnet synchronous machine G PSM q and an offset disturbance of 0 d . G PSM q i st including a 1x2 matrix that describes the transfer of dq voltage to the torque-generating q current and from the last column of a PSM model G PSMThe invention describes, by way of example, the optimization of the q-current for reducing acceleration signals. This is based on the assumption, derived from preliminary physical considerations, that the q-current primarily generates tangential and normal forces that cause accelerations, NVH (noise, vibration, and harshness). Alternatively, the d-current can also be used for reduction, or both d- and q-currents can be used to reduce acceleration signals at multiple measuring points. For example, the following equation is used to calculate the harmonic frequency: where ω mech = 2nf mech the mechanical angular frequency and ω el = N P ω mech the electrical angular frequency. The PSM model can be inverted, and the inverted matrix yields: where R is the resistance of the stator winding and L d / qabout the d- or q-inductance of the stator winding. If the complex notation is omitted, the following results in real form: Since, as described above, it is assumed that mainly the i q -Current radial and tangential force ripples and thus accelerations are caused by the i d -current is omitted, and the following results for the model matrix: This matrix can be used for the inversion of G PSM q (j ■ d ) be used. The further transfer from the q-current to the MEMS signal is unknown, but is to be identified during operation and is referred to beforehand as G. MEMS designated. In the noise reduction application shown, only the transfer behavior for the harmonic frequency is considered. d used: GMEMS (j ' "d) = Real + j ■ Imag (6) Where Real denotes the real part and Imag the imaginary part, which are unknown and are to be determined as part of the transmission parameters. The inverse of the steady-state current-acceleration behavior in real form is thus: The following relationship applies: with the cosine component of the q-current 0 c i(j , the sinusoidal component of the q-current 0 s i(j , the cosine component of the acceleration signal 0 cy and the sine component of the acceleration signal 0 sy . If a current now flows through the electrical machine, whereby a current disturbance is imposed on the q-current, the transmission parameters can be estimated using an information matrix decomposition least squares method. For each revolution k, the sine and cosine components of the acceleration signal and the q-current are calculated: ®y = ®s,y + j®c,y (9) ®i q= ®s,i q + j®c,i q (10) Substituting into equation (1) using the relationship from equation (4) yields: ®y — ^MEMS®^ + ®d (11) The I MD LS method uses the following measurement parameters and available to estimate the unknown transmission parameters p required for adaptive noise reduction control: Further details on how to carry out the estimation procedure can be found, for example, in DE 102023207191 A1, in particular paragraphs

[0052] to

[0057] , disclosed. The invention is schematically illustrated in the drawing using exemplary embodiments and is described below with reference to the drawing. Brief description of the drawings Figure 1 shows a schematic representation of a block diagram of an electric drive system according to one embodiment, Figure 2 shows a block diagram of an overall control structure, such as it can be the basis of the invention Figure 3 shows a flowchart of an embodiment of the method according to the invention, and Figures 4a to 4e show simulation results for a course of various parameters relevant to an embodiment of the method according to the invention. Embodiments of the invention Figure 1 shows a schematic representation of a block diagram of an electric drive system 100 with a device 110 for controlling or Energizing a stator winding of the stator of an electric machine. Such a device is also called an inverter. The electric drive system 100, for example, comprises an electric machine 130 with a stator and a rotor, which is driven by a The converter circuit 111 of the device 110 can be powered. For this purpose, the converter circuit 111 can be powered, for example, by a DC voltage source such as a battery 120 or similar. The example of a three-phase electric machine 130 shown here serves only for better understanding and does not represent a limitation of the present invention. Furthermore, any electric machine 130 with a different number of electrical phases than three is of course also possible. For example, it could also be a six-phase electric machine 130 or an electric machine 130 with any other number of phases. To control the stator winding of the electric machine 130, the converter circuit 111 can convert the DC voltage supplied by the battery 120 into a suitable AC voltage. In the case of a three-phase electric machine 130, the converter circuit 111 can, for example, convert the DC voltage into a three-phase AC voltage. In this process, the amplitude of the AC voltage and / or the value of the output current from the converter circuit 111 to the stator winding (phase windings) of the electric machine 130 can be set based on a predefined setpoint curve 140. For example, the converter circuit 111 can be a converter circuit with multiple half-bridges. In particular, the converter circuit 111 can comprise at least one half-bridge with two switching elements for each phase of the electric machine 30. Thus, the converter circuit 111 for a three-phase electric machine 30 can, for example, have a B6 topology. The switching elements of the converter circuit 111 can be controlled by a processing unit 112 of the device 110 using suitable control signals based on the setpoint specification 140. The processing unit 112 can, for example, provide a control signal for each switching element of the converter circuit 111 to open or close the corresponding switching element. The control of an upper switching element of a half-bridge is typically complementary to the control of the corresponding lower switching element. Figure 2 shows a block diagram of an overall control structure 1, as it may form the basis of the invention and with which an electric machine 4, for example corresponding to the electric machine 130 according to Figure 1, is controlled. The electric machine 4 may, for example, be a permanent magnet synchronous machine (PSM). The overall control structure 1 without the electric machine 4 and any sensors may be implemented in the computing unit 112 of Figure 1. The overall control structure 1 includes a harmonic control 2, which uses a voltage correction parameter (Au). dq ) 22 is designed to influence the desired harmonic, and a decoupling unit 6 provides a decoupling current (Ai) d(? ) 61 for dynamic decoupling as a function of the voltage correction quantity 22. Various known methods can be used for this purpose, which will not be discussed in detail here. The voltage correction value 22 is determined by the harmonic control 2 as a function of an acceleration signal 41, transmission parameters 51, and target acceleration components 21, and serves to reduce one or more specific harmonics. The acceleration signal 41 is measured, for example, by a MEMS sensor arranged on the electric machine 4. An example of the setup of the harmonic control 2 and the method for determining the voltage correction value 22 is shown in DE 102023207 191 A1, in particular in paragraphs

[0073] to

[0079] revealed. Furthermore, the overall control structure 1 includes a field-oriented control 3 (FOR, English: Field Oriented Control, FOC), which determines a voltage control variable 32 for the electrical machine 4 from an applied control deviation 12 (in a known way; vector control). In the present case, the field-oriented control 3 is corrected by a control deviation or difference 12 M, adjusted by the decoupling current 61 (additively). dq (=M d , M q )) between target value (i dq (=i d ,i q )) 11 and actual value (i dq (=i d ,i q )) 43 of the current is supplied through the stator winding in the d / q coordinate system, from which the Voltage control variable 32 is also determined in the d / q coordinate system. This correction is performed in two steps in the figure, whereby first the actual value 43 is reduced by the decoupling current 61, and then this result is subtracted from the target value 11. This leads to a decoupling of the applied current harmonic from FOR 3, since the latter would otherwise dampen or reduce the harmonic correction. The voltage setting parameter 32 is (additively) combined with the voltage correction parameter (Au). dq ) 22 to a corrected voltage control variable (udq ) 33 is calculated, which controls the electric machine 4. In operation, this results in the actual value 43 of the current, in particular the q-current 42, and an actual value of the acceleration (y) 41. The transmission parameters 51 are determined in a transmission parameter determination unit 5 as a function of the acceleration signal 41 and the q-current (i q ) 42 determined. The method according to the invention is used for this purpose. Figure 3 shows a flowchart of an embodiment of the method according to the invention. In step 200, the electric machine is controlled with a voltage control variable 32, causing a current to flow through the electric machine 4. This current fulfills a torque requirement for the electric machine 4 and is subjected to a current disturbance with a predetermined amplitude and frequency. For this purpose, an excitation signal 31 can be output to the field-oriented control 3. The excitation signal 31 alternately supplies the field-oriented control 3 with a current with an amplitude of, for example, +1 A and -1 A, at intervals of one second. This current is added to the setpoint values ​​11 for the current and the control deviation 12, respectively. A larger amplitude leads to a faster and more accurate determination of the transfer parameters 51. However, a larger amplitude of the current disturbance also amplifies noise generation. Due to the transient response of the field-oriented control and the Fast Fourier Transform calculation of the measured current values, a sinusoidal current waveform is calculated by the field-oriented control 3. The voltage control variable 32, determined by the field-oriented control 3, causes a current to flow through the electric machine 4 that fulfills the torque requirement. The excitation component 31 imposes the current disturbance on the current flowing through the electric machine 4. The excitation component 31 can affect only one of the d-currents and the q-currents, for example, only the q-current. While the electric machine 4 is being controlled with the voltage control variable 32, the current 42 flowing through the stator winding, for example the q-current, and the acceleration signal 41 are detected in step 210. The current 42 flowing through the stator windings and the acceleration signal 41 are output to the transmission parameter determination unit 5. Furthermore, while the electric machine 4 is being controlled with the voltage control variable 32, the noise reduction by the harmonic control 2 is reduced so that the current disturbance is not filtered out of the signal by the harmonic control 2.For example, the voltage correction parameter 22, determined by the harmonic control 2 to reduce interference on the acceleration signal 41 and the current 42 flowing through the stator windings of the electric machine 4, can be multiplied by a factor less than 1, which also includes multiplication by zero, i.e., deactivation. Alternatively, the harmonic control 2 can be completely deactivated during the control of the electric machine 2 with the voltage control parameter 32. The transfer parameter determination unit 5 determines, in step 220, the transfer parameters 51, which represent a transfer behavior between the detected current 42 and the detected acceleration signal 41, depending on the detected current 42 and the detected acceleration signal 41. A suitable estimation method, for example an information matrix decomposition least squares method, can be used for this purpose, as described. The transfer parameters 51 are, for example, a The real and imaginary parts of a transmission matrix, as well as an offset disturbance, are used. Alternatively, the use of a gradient-based estimation method to determine the transmission parameters 51 is also conceivable. The determined transmission parameters 51 are then used to control the electric machine 4. For this purpose, the transmission parameters 51 are output to the harmonic control 2, which uses them to determine the voltage correction quantity 32 (see above). Figures 4a to 4e show simulation results for a course of various parameters relevant to an embodiment of the method according to the invention. The x-axis 301 shows the time course in seconds. The electric machine 4 is operated with a torque requirement of 3 Nm and a speed of 100 RPM in the range from 0 to 40 s, and in the range from 40 s onwards with a torque requirement of 3 Nm and a speed of 120 RPM. Figure 4a shows the amplitude of the current harmonic, e.g., in Ω, for the 12th order current harmonic. Figure 4b shows the corresponding, correct phase angle, e.g., in radians. Figure 311 shows the current waveform of the current harmonic when the method according to the invention is carried out with a current disturbance having an amplitude of 1 A, while figure 312 shows the current waveform of the current harmonic when the method according to the invention is carried out with a current disturbance having an amplitude of 0.5 A. Similarly, figure 321 shows the phase response of the current harmonic when the method according to the invention is carried out with a current disturbance having an amplitude of 1 A, and figure 322 shows the phase response of the current harmonic when the method according to the invention is carried out with a current disturbance having an amplitude of 0.5 A. In the range from 0 s to 10 s, no regulation of the current harmonics takes place and the harmonic leads to noise and vibration pollution. The electrical disturbances are applied during the time periods of 10 to 20 seconds and 50 to 60 seconds. During these periods, the noise reduction provided by harmonic control 2 is reduced or completely deactivated. In the other time periods, noise reduction is provided by harmonic control 2. Figure 4c shows the curve for the estimated real part of the transfer matrix. Figure 4d shows the curve for the estimated imaginary part of the transfer matrix. Specifically, curve 331 of the real part and curve 341 of the imaginary part are shown for a current disturbance with an amplitude of 1 A, and curve 332 of the real part and curve 342 of the imaginary part are shown for a current disturbance with an amplitude of 0.5 A. Lines 333 and 334 show the actual and correct values ​​for the real part, respectively, while lines 343 and 344 show the actual and correct values ​​for the imaginary part, respectively. It can be seen that for an amplitude of 1 A for the current disturbance, the course of the real and imaginary part 331, 341 is closer to the real value 333, 334, 343, 344 than the course of the real and imaginary part 332, 342 for the amplitude of 0.5 A. Figure 4e shows the amplitude curve 351 of an NVH signal or noise for a selected frequency, for which a Fourier analysis of the acceleration signal 41 is performed at the frequency relevant for noise generation. Again, the amplitude curve 351 of the acceleration signal is shown during a current disturbance with an amplitude of 1 A, while the amplitude curve 325 of the acceleration signal is shown during a current disturbance with an amplitude of 0.5 A. It is clearly evident that outside the regions where the current disturbance is excited, the amplitudes drop to zero within a very short time, meaning that no oscillations generating noise are present at this frequency.

Claims

Claims 1. Method for controlling an electrical machine (4), the electrical machine (4) comprising a stator with a stator winding and a rotor, the procedure comprehensively: Controlling (200) the electric machine (4) with a voltage control variable (32) so that a current flows through the stator winding of the electric machine (4) by which a torque requirement on the electric machine (4) is fulfilled and on which a current disturbance with a predetermined amplitude and a predetermined frequency is superimposed, detecting (210) the current (42) flowing through the stator windings and an acceleration signal (41), Determining (220) transmission parameters (51) that represent a transmission behavior between the detected current (42) and the detected acceleration signal (41), depending on the detected current (42) and the detected acceleration signal (41), Using (230) the specified transmission parameters (51) to control the electric machine (4).

2. Method according to claim 1, wherein determining (220) the transmission parameters (51) comprises determining the transmission parameters (51) using an estimation method, an Information Matrix Decomposition Least Squares (IMDLS) method or a gradient-based estimation method.

3. Method according to one of the preceding claims, wherein the determination (220) of the transmission parameters (51) is further carried out as a function of a harmonic frequency of the acceleration signal (41), which in particular depends on the electrical angular frequency of the electrical machine (4).

4. Method according to one of the preceding claims, wherein the transmission parameters (51) comprise a real part (331, 332) and an imaginary part (341, 342) of a transmission matrix which maps a transmission of a current (42) through the stator winding of the electrical machine (4) to the acceleration signal (41), and an offset disturbance.

5. Method according to one of the preceding claims, wherein during the actuation (200) of the electric machine (4) with the voltage control variable (32) a method for noise reduction, which is carried out in particular by a harmonic control (2) of the electric machine (4), which counteracts a disturbance on the acceleration signal (41) and the current (42) flowing through the stator winding of the electric machine (4), is carried out with a reduced effect.

6. Device (110) for controlling an electric machine (140), the electric machine (140) comprising a stator with a stator winding and a rotor, comprising the device (110): a power converter circuit (111) configured to be coupled to the stator winding of the electrical machine (140) and to provide an electrical voltage for controlling the stator winding of the electrical machine (140); and a computing unit (112) configured to perform all process steps of a method according to one of the preceding claims.

7. Electric drive system (100), with: a device (110) for controlling an electric machine according to claim 6, and an electric machine (140) comprising a stator with a stator winding and a rotor, wherein the electric machine (140) is electrically coupled to the converter circuit (111) of the device (110) for controlling the electric machine.

8. Computer program that causes the computing unit (112) of the device (110) for controlling an electric machine according to claim 6 or the electric drive system (100) according to claim 7 to carry out all process steps of a method according to any one of claims 1 to 5 when executed on the computing unit.

9. Machine-readable storage medium with a computer program stored thereon according to claim 8.

Images