Method for operating a drive unit and drive unit

Abstract

The invention relates to a method for operating a drive unit (100) with an electric machine (1) comprising a rotor, in particular with a plurality of permanent magnets, and a stator with a plurality of phase windings and a converter circuit (20) for controlling the electric machine (1), comprising at least one half-bridge with a first controllable semiconductor switching element and a second controllable semiconductor switching element. In the method, a profile of the stator voltage applied to the plurality of phase windings and a profile of a stator current (i) flowing through the electric machine (1) are recorded. ist ) detected (S100), depending on the detected stator voltage profile and the detected stator current profile (i ist ) using a disturbance observer to observe the course of a disturbance (ufunddist) the stator voltage or a fault (ifunddist) of the stator current (S110). Subsequently, the electrical machine (1) is controlled using the course of the disturbance. (ufunddist) the stator voltage or the fault (ifunddist) the stator current is controlled (S120). The invention further relates to a drive unit (100).

Description

[0001] The present invention relates to a method for operating a drive unit as well as a drive unit, a computing unit and a computer program for carrying out the method. Background of the invention

[0002] Electric drives, or electric machines used as drives, for example in fully or partially electric vehicles, can be controlled by pulse width modulation (PWM) with field-oriented control (FOC). Since the torque of the electric machine is primarily generated by the fundamental frequency of the stator current, the common control methods (e.g., field-oriented control) are fundamental-frequency control methods.

[0003] Synchronous pulse patterns enable higher amplitudes of the fundamental frequency in the terminal voltage, for example through block commutation, and thus higher power output from the electric drive. Furthermore, operation with synchronously optimized pulse patterns allows the electric machine to operate with lower losses. Control with synchronous pulse patterns or synchronous modulation is conventionally used at steady-state operating points and / or very high speeds. Tracking controllers are used for dynamic control with synchronous pulse patterns. Flux tracking control, e.g. BN Oikonomou and J. Holtz, “Stator Flux Trajectory Tracking Control for High-Performance Drives”, Conference Record of the 2006 IEEE Industry Applications Conference Forty-First IAS Annual Meeting, 2006, pp. 1268-1275, doi: 10.1109 / IAS.2006 .256694.) or model predictive control approachesModel Predictive Control (MPC) (e.g., T. Geyer, N. Oikonomou, G. Papafotiou, and F. Kieferndorf, "Model predictive pulse pattern control," IEEE Energy Conversion Congress and Exposition, 2011, pp. 3306–3313, doi: 10.1109 / ECCE.2011.6064215) can be found in the literature. These controllers require correct reference trajectories or reference waveforms of the stator voltage and / or stator current for proper operation.

[0004] Unlike fundamental-frequency control methods, synchronous modulation does not allow for the direct application of the relationship between stator current and torque, as the fundamental frequency of the stator current, unlike in PWM modulation, cannot be easily measured. Furthermore, adjusting the stator voltage at each sampling interval may be limited, and a change in the pulse pattern can lead to system excitation.

[0005] The reference curve or reference waveform used in follow-up control (e.g., MPC or flux tracking) must include the harmonics. Follow-up control requires consistent stator voltage and stator current waveforms, as the pulse pattern is selected depending on the desired stator voltage, and the follow-up controller attempts to force the machine or stator current to conform to the corresponding current setpoint.

[0006] The reference stator current waveform for the tracking control consists of the fundamental frequency and one or more harmonics. The harmonics induced by the switching of the semiconductor switching elements in a power converter circuit designed to supply electrical power to the electric machine depend on the synchronous pulse patterns used and the differential inductance, and can therefore be calculated. The fundamental frequency of the stator current depends on the behavior of the electric machine and can be determined, for example, by models. Model inaccuracies, such as those caused by temperature drift of the electric machine, affect the waveform of the fundamental frequency. Therefore, to obtain the correct waveform of the fundamental frequency, a correction of the reference stator current waveform is necessary. Disclosure of the invention

[0007] According to the invention, a method for operating a drive unit, as well as a drive unit, a computing unit, 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.

[0008] The invention relates to a drive unit comprising an electric machine with a rotor, in particular with a plurality of permanent magnets, and a stator with a plurality of phase windings, and a converter circuit for controlling the electric machine (1) comprising at least one half-bridge with a first controllable semiconductor switching element and a second controllable semiconductor switching element. As already mentioned above, the control of the semiconductor switching elements can be effected by means of synchronous pulse patterns, in particular by a tracking control.

[0009] By using synchronous pulse patterns, higher power outputs (block commutation) and higher efficiency (optimal pulse patterns) of the electric machine or drive unit can be achieved.

[0010] The reference stator current profile for the pulse pattern to be used can be determined for each pulse pattern using a model. However, inaccuracies in the model or temperature fluctuations during operation of the drive unit lead to incorrect fundamental oscillations in the stator current profiles, which do not match the corresponding fundamental oscillations of the stator voltage generated by the pulse pattern used. Based on the required fundamental oscillation of the stator voltage, a pulse pattern is selected, and the tracking controller attempts to force the stator current to conform to the corresponding reference profile. In the event of a model error, the given reference stator current profile does not match the actual profile, and the tracking controller must continuously follow the selected pulse pattern, preventing steady-state operation.

[0011] Therefore, for the implementation of a follow-up control in dynamic operation, the most accurate possible reference curve (or reference trajectory) of the stator current should be determined, as otherwise the aforementioned advantages over a conventional field-oriented control cannot be achieved or the follow-up control cannot be carried out correctly.

[0012] The invention employs a disturbance observer that uses the stator voltage and stator current to determine the course of a disturbance in the stator voltage or stator current, from which a correct reference course of the stator voltage or stator current can then be determined. Based on these reference courses, the synchronous pulse pattern for controlling the electric machine is subsequently determined.

[0013] By determining the correct reference curve of the stator voltage and / or the stator current, the control of the electrical machine in dynamic operation can be carried out using synchronous pulse patterns.

[0014] By using synchronous pulse patterns throughout the entire operation of the electric machine, i.e. not only during steady-state or constant operation where there are no changes in the torque generated by the electric machine, the power and efficiency of the electric machine can be increased.

[0015] Furthermore, by using a disturbance observer to determine the reference trajectory, an exact model of the electrical machine is not necessary, thus reducing the computational effort required to determine the reference trajectory.

[0016] Specifically, the invention relates to a method in which the stator voltage(s) applied to a plurality of phase windings and the stator current flowing through the plurality of phase windings are detected. Subsequently, the course of a disturbance in the stator voltage or the course of a disturbance in the stator current is determined as a function of the detected course of the stator voltage and the detected course of the stator current using a disturbance observer. The electric machine is controlled or operated using the course of the disturbance in the stator voltage or the disturbance in the stator current. Synchronous pulse patterns and / or a tracking controller, in particular a flux tracking controller or current tracking controller, are used in particular for controlling or operating the electric machine.In particular, a model predictive control is used, which shifts the switching times of the converter circuit depending on a deviation of the stator current from a calculated target stator current profile.

[0017] By using the disturbance observer, the reference curve of the stator current and / or the stator voltage can be determined with particular accuracy, thereby achieving the aforementioned advantages.

[0018] In one embodiment, the disturbance observer used to determine the course of the disturbance in the stator voltage or the disturbance in the stator current is of the Kalman filter type. By using the Kalman filter, the course of the disturbance can be determined with particular accuracy, so that the correct pulse pattern can be determined and thus the electrical machine can be operated with high efficiency.

[0019] In the following, an exemplary implementation for determining the course of the disturbance of the stator voltage using a Kalman filter will be briefly explained using equations:

[0020] The model of an electrical machine with input disturbance can be represented, for example, by the following equation: (ddtid(t)ddtiq(t))=[−RLdωelLqLd−ωelLqLd−RLq]⋅(id(t)iq(t))++[1Ld001Lq]⋅((ud(t)uq(t))+(uddist(t)uqdist(t)))+(0−ωel⋅ψPMLq) =A⋅idq(t)+B⋅(udq(t)+ufunddist(t))+f

[0021] With the course of the stator current i d (t), i q (t) in dq coordinates, a resistance R of the phase windings of the electrical machine, the inductance L d , L q the phase windings of the electrical machine in dq coordinates, the electrical position angle ω el , summarized in the system matrix A and the input matrix B, the course of the fundamental oscillation of the stator voltage ud (t), u q (t) in dq coordinates, the course of the disturbance uddist(t),uqdist(t) the stator voltage in dq coordinates, summarized as the course of the disturbance ufunddist(t) the stator voltage, and a flux Ψ PM through the phase windings of the electrical machine, summarized in the affine vector f of a linear state-space model.

[0022] The Kalman filter then determines the disturbance according to the following system of equations: (idq(k+1)ufunddist(k+1))=[AB02×2I2×2]⋅(idq(k)ufunddist(k))⋅(B02×2)⋅udq(k)+fD 0 2×2 describes a 2x2 zero matrix and I 2×2 a 2x2 identity matrix.

[0023] Furthermore, it is assumed that the disruption ufunddist(k+1) at a time k + 1 equal to the disturbance ufunddist(k) at time k. This assumption is justified because, unlike the fundamental oscillation, the course of the disturbance is not due to the switching of the individual semiconductor switching elements but mainly to external factors, such as the change in the temperature of the electrical machine, and therefore remains unchanged over time.

[0024] This was demonstrated for the temperature on a test bench. However, this assumption can also be applied to other model errors.

[0025] The inputs to the disturbance observer are the measured stator current and stator voltage. The stator voltage is set by a follower regulator and contains harmonics. The measured stator current also contains harmonics. Therefore, the stator voltage and stator current are consistent, and no error is induced by the harmonics. Thus, these inputs can be used to estimate the disturbance waveform. ufunddist(t) The stator voltage is used. With the estimated course of the disturbance ufunddist(t) The applied fundamental frequency of the stator voltage for the electric machine can be corrected using the stator voltage. With the corrected stator voltage, the correct pulse pattern for pulse width modulation can be determined or selected, matching the given fundamental frequency of the stator current, which is determined based on the specified torque. The same principle can be used analogously to determine a disturbance in the stator current.

[0026] In one embodiment, controlling the electric machine further comprises determining a reference curve of a fundamental oscillation of the stator current and a reference curve of a fundamental oscillation of the stator voltage as a function of the course of the disturbance of the stator voltage or the disturbance of the stator current and a target torque to be provided by the electric machine, and determining a synchronous pulse pattern for controlling the electric machine as a function of the determined reference curve of the fundamental oscillation of the stator current and the determined reference curve of the fundamental oscillation of the stator voltage.Determining the synchronous pulse pattern for controlling the electric machine involves, in particular, selecting a basic pulse pattern from a multitude of synchronous pulse patterns depending on the defined reference waveform of the fundamental stator voltage, and determining a current harmonic that would be induced by switching the first and second controllable semiconductor switching elements based on the basic pulse pattern. Different waveforms of current harmonics that would be induced by the available synchronous basic pulse patterns can, for example, be stored in a memory unit as offline pre-calculated current harmonics derived from the synchronous basic pulse pattern and retrieved after selecting the synchronous basic pulse pattern.Subsequently, a target stator current profile is determined, in particular by adding the reference profile of the fundamental oscillation of the stator current and the current harmonics, and the synchronous pulse pattern used to control the electrical machine is determined as a function of the stator current profile flowing through the multitude of phase windings, the synchronous basic pulse pattern and the determined target stator current profile.

[0027] This allows the electric machine to be controlled in a simple way.

[0028] In one embodiment, an optimization problem is solved to determine the reference waveforms of the fundamental stator current and the fundamental stator voltage. Specifically, the optimization problem minimizes a cost function that incorporates both the magnitude of the deviation between the torque achievable by the fundamental stator current and the torque to be provided, as well as the magnitude of the stator current itself. The influence of the stator current on the cost function can be adjusted by a weighting factor.

[0029] The torque achievable by the fundamental oscillation of the stator current of the electric machine is, in particular, a function of the reference waveform of the fundamental oscillation of the stator current and the electric angular velocity of the electric machine. Furthermore, in the optimization problem, it must be satisfied that the time variation of the stator current waveform is zero and / or that the magnitude of the amplitude of the reference waveform of the fundamental oscillation of the stator current is less than or equal to the magnitude of a maximum permissible stator current, and that the magnitude of the amplitude of the reference waveform of the fundamental oscillation of the stator voltage is less than or equal to the magnitude of a maximum permissible stator voltage.

[0030] Expressed in terms of equations, the optimization problem can be represented as follows: minimizeifundref,ufundref,Tfundref(Tfundref−Tdes)2+w⋅(ifundrefTifundref) with the torque T to be provided des, the torque achievable through the fundamental oscillation of the stator current Tfundref, a weighting factor w, where in particular w > 0 and w << 1 and the reference curve of the stator current Tfundref. The minimum of the absolute value can, for example, be replaced by the minimum of a quadratic function, which simplifies the calculation.

[0031] It should be noted that the reference curve of the stator current ifundref a vector in the dq coordinate system and therefore has a d and a q component. The torque achievable through the fundamental oscillation of the stator current. Tfundref This depends on the reference curve of the fundamental oscillation of the stator current. ifundref and the electric angular velocity of the electric machine: Tfundref=ftorque(ifundref,ωel) where f Drehmomentis a torque equation of the electric machine.

[0032] Furthermore, to solve equation (3), it is used that the reference waveforms of the fundamental oscillation of the stator current are ifundref and the stator voltage ufundref In static operation, i.e., when the derivative of the stator current is zero, this represents a solution to the motor equation: 0=A(ωel)⋅ifundref+B⋅(ufundref+ufunddist)+f(ωel)

[0033] Equation (5) corresponds to equation (1), where the reference stator voltage waveform is used and the time-dependent change of the stator current is zero. Furthermore, the magnitude of the amplitude of the reference stator current waveform is less than or equal to the magnitude of a maximum permissible stator current, and the magnitude of the amplitude of the reference stator voltage waveform is less than or equal to the magnitude of a maximum permissible stator voltage. ‖ifundref‖22≤IMax2,‖ufundref‖22≤UMax2

[0034] By applying the optimization problem to determine the reference curves of the stator voltage and stator current, these can be determined with low computational effort and at the same time accurately.

[0035] In one embodiment, the detection of the course of the stator voltage applied to the plurality of phase windings and the course of the stator current flowing through the plurality of phase windings comprises the detection of a synchronous pulse pattern used to control the electrical machine and the determination of the stator voltage based on or depending on the detected synchronous pulse pattern, in particular by determining a value of the stator voltage at a time as an average value over a sampling period of the received synchronous pulse pattern containing that time.

[0036] While determining the stator voltage based on the captured synchronous pulse pattern leads to a small error, the computational effort for determining the course of the disturbance is significantly lower, since fixed step sizes can be used to solve the differential equations instead of variable step sizes, which take into account every change in the pulse pattern and thus smaller step sizes.

[0037] In one embodiment, the detection of the course of the stator voltage applied to the plurality of phase windings and the course of the stator current flowing through the plurality of phase windings comprises measuring the course of the stator current flowing through the plurality of phase windings by means of one or more current sensors, wherein the one or more current sensors are arranged between the converter circuit and one of the plurality of phase windings.

[0038] This allows the stator current flowing through the electric machine to be measured in a simple and cost-effective manner.

[0039] A computing unit according to the invention, e.g. a control unit of a drive unit or a motor vehicle, is, in particular in terms of programming, equipped to carry out a method according to the invention.

[0040] 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 control 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 media, 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.).

[0041] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0042] The invention is schematically illustrated in the drawing using an exemplary embodiment and is described below with reference to the drawing. Brief description of the drawings Fig. Figure 1 shows a block diagram of an embodiment of a drive unit that is set up to carry out the method according to the invention, and Fig. Figure 2 shows a flowchart of an embodiment of the method according to the invention. embodiment of the invention

[0043] Fig. Figure 1 shows a block diagram of an embodiment of a drive unit 100, which is set up to carry out the method according to the invention, and Fig.Figure 2 shows a flowchart of an embodiment of the method according to the invention. Both figures will be described together in the following.

[0044] The drive unit 100 comprises an electric machine 1, a power converter circuit 20, and a computing unit 10, which is configured to carry out an embodiment of the method according to the invention. In the embodiment shown, the electric machine 1 is a three-phase electric machine 1 with phase windings that are supplied with electrical power by the power converter circuit 20. The power converter circuit 20 has three half-bridges (one per phase), each half-bridge comprising a first controllable semiconductor switching element and a second controllable semiconductor switching element. The first controllable semiconductor switching element is arranged between a first DC voltage terminal and a center terminal of the power converter circuit 20, via which a phase winding is supplied with electrical power.The second controllable semiconductor switching element is arranged between a second DC voltage terminal and the center terminal. In the case of the three-phase electric machine 1, the converter circuit 20 has three half-bridges, each with a separate center terminal through which one of the phase windings is supplied with electrical power. The first and second DC voltage terminals can, for example, be the terminals of a battery, in particular a high-voltage battery (battery voltage greater than or equal to 60 V), which is installed in the vehicle in which the drive unit 100 is also installed.

[0045] To control the power converter circuit 20 and the electric machine 1, the computing unit 10 transmits synchronous pulse patterns u SPMto the power converter circuit 20, by means of which the first and second controllable semiconductor switching elements in each of the half-bridges are controlled. The control of the electric machine 1 is to be carried out in particular by means of synchronous optimal pulse patterns and / or block commutation.

[0046] To determine the synchronous pulse patterns u SPM In the computing unit 10, a reference curve of the stator voltage, i.e. the voltage applied to the phase windings of the electrical machine 1, and / or of the stator current, i.e. the current flowing through the phase windings of the electrical machine 1, is required as accurately as possible.

[0047] To determine the reference curves of the stator voltage ureffund and the stator current ireffund The computing unit 10 has a reference trend determination unit 11.

[0048] The reference curve determination unit 10 records a curve (actual curve) of the stator voltage applied to the multitude of phase windings in step S100. ist and a course (actual course) of a stator current i flowing through the multitude of phase windings ist .

[0049] To determine the actual stator voltage curve u ist In step S101, for example, the synchronous pulse pattern u can be obtained from a fault detection unit 11a of the reference detection unit 11. SPM received and in step S102 based on the received synchronous pulse pattern u SPM the actual course of the stator voltage u ist can be determined. For example, any value of the stator voltage at a given time can be determined as the average value over a sampling period of the received synchronous pulse pattern that includes that time. SPM be determined.

[0050] The actual course of the stator current i flowing through the electric machine 1ist The current can be measured in step S103, using, for example, one or more current sensors. The current sensors can be arranged, for example, between one of the center terminals and one of the terminals of the electric machine 1, or in the converter circuit between the DC terminal (the first or the second) and the controllable semiconductor switching element, or between the controllable semiconductor element and the center terminal.

[0051] In step S110, a fault progression is recorded in the fault determination unit 11a. ufunddist the stator voltage applied to the electrical machine 1 (or alternatively a disturbance of the stator current) as a function of the detected course of the stator voltage u ist and the recorded course of the stator current i istdetermined using a disturbance observer. The disturbance observer is, in particular, a Kalman filter type, which measures the course of the disturbance. ufunddist the stator voltage applied to the electrical machine 1 is determined, for example, using equations (1) and (2).

[0052] Subsequently, in step S120, the electrical machine 1 is controlled using the course of the disturbance. ufunddist The stator voltage (or the disturbance of the stator current) applied to the electric machine 1 is controlled.

[0053] For this purpose, in step S121 a reference curve of a fundamental oscillation of the stator current is obtained. ifundref and a reference curve of a fundamental oscillation of the stator voltage ufundref depending on the specific course of the disorder ifunddist the stator voltage applied to the electric machine 1 and a target torque M to be provided by the electric machine 1 Soll in a fundamental frequency determination unit 11b of the reference response determination unit 11. For determining the reference response of the fundamental frequency of the stator voltage. ufundref and the stator current ifundref In particular, an optimization problem is solved. For example, the method outlined above using equations (3) to (6) can be used to solve the optimization problem.

[0054] Subsequently, in step S122, the synchronous pulse pattern u is determined in a pulse pattern determination unit 12. SPM for controlling the electric machine 1 depending on the specific reference curve of the fundamental oscillation of the stator current. ifundref and the specific reference curve of the fundamental oscillation of the stator voltage ufundref certainly.

[0055] In step S122a, a synchronous basic pulse pattern is generated. P in a pulse pattern selection unit 12a of the pulse pattern determination unit 12 from a multitude of synchronous pulse patterns depending on the determined reference curve of the fundamental oscillation of the stator voltage ufundref chosen.

[0056] In step S122b, a current harmonic i is still being used in the pulse pattern selection unit 12a. harm , which are achieved by switching the first and second controllable semiconductor switching elements based on the synchronous basic pulse pattern u PM would be induced, determined. The course of the current harmonics i harm , which would be induced by the available synchronous base pulse patterns, can, for example, take the form of itself arising from the synchronous base pulse pattern u PMThe resulting, offline pre-calculated current harmonics are stored in a memory unit and, after selection of the synchronous base pulse pattern, u PM can be retrieved.

[0057] In step S122c, a target current profile of the stator current is determined in a target current profile determination unit 12b as a function of the selected basic pulse pattern u. PM , in particular by adding the reference waveform of the fundamental oscillation of the stator current ifundref and the basic pulse pattern u PM associated current harmonics i harm , certainly.

[0058] In step S122d, the synchronous pulse pattern u used to control the electric machine 1 is selected in a subsequent controller 12c of the pulse pattern determination unit 12. SPM depending on the course of the stator current flowing through the multitude of phase windings i ist, the specified target stator current profile and the specified synchronous base pulse pattern u PM certainly.

[0059] In particular, the synchronous basic pulse pattern u PM The predetermined switching points of the converter circuit are shifted depending on the deviation of the stator current from a calculated target stator current curve in order to achieve the synchronous pulse pattern u. SPM to obtain.

[0060] The resulting synchronous pulse pattern u SPM The processing unit 10 outputs the signal to the power converter circuit 20, which selects the controllable semiconductor switching elements based on the received synchronous pulse pattern u. SPM controls. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] J. Holtz, “Stator Flux Trajectory Tracking Control for High-Performance Drives,” Conference Record of the 2006 IEEE Industry Applications Conference Forty-First IAS Annual Meeting, 2006, pp. 1268-1275, doi: 10.1109 / IAS.2006 .256694

[0003] T. Geyer, N. Oikonomou, G. Papafotiou and F. Kieferndorf, “Model predictive pulse pattern control,” 2011 IEEE Energy Conversion Congress and Exposition, 2011, pp. 3306-3313, doi: 10.1109 / ECCE.2011.6064215

[0003]

Claims

[1] Method for operating a drive unit (100) with - an electric machine (1) comprising a rotor, in particular with a plurality of permanent magnets, and a stator with a plurality of phase windings and - a power converter circuit (20) for controlling the electric machine (1) comprising at least one half-bridge with a first controllable semiconductor switching element and a second controllable semiconductor switching element, the method comprising: Detection (S100) of a stator voltage profile applied to the multitude of phase windings (u ist ) and the course of a stator current flowing through the multitude of phase windings (i ist ), Determining (S110) the course of a disorder (ufunddist) the stator voltage or a course of a disturbance of the stator current as a function of the detected course of the stator voltage (u ist) and the recorded course of the stator current (i ist ) using a disturbance observer, Control (S120) of the electric machine (1) using the course of the disturbance (ufunddist) the stator voltage or the disturbance of the stator current. [2] Method according to claim 1, wherein the method for determining (S110) the course of the disturbance (ufunddist) The disturbance observer used to monitor the stator voltage or the course of the disturbance of the stator current is of the Kalman filter type. [3] Method according to claim 1 or 2, wherein the control (S120) of the electric machine (1) further comprises: Determining (S121) a reference waveform of a fundamental oscillation of the stator current (ifundref) and a reference curve of a fundamental oscillation of the stator voltage (ufundref) depending on the course of the disorder (ufunddist) the stator voltage or the disturbance of the stator current and a target torque (M) to be provided by the electrical machine (1) Soll ), Determining (S122) a synchronous pulse pattern (u SPM ) for controlling the electrical machine (1) depending on the specific reference waveform of the fundamental oscillation of the stator current (ifundref) and the specific reference curve of the fundamental oscillation of the stator voltage (ufundref). [4] Method according to claim 3, wherein determining (S122) the synchronous pulse pattern (u SPM ) for controlling the electric machine (1) includes: Selecting (S122a) a synchronous basic pulse pattern (u PM ) from a multitude of synchronous pulse patterns depending on the specific reference curve of the fundamental oscillation of the stator voltage (ufundref), Determine (S122b) a stream harmonic (i harm), which are controlled by switching the first and second controllable semiconductor switching elements based on the synchronous basic pulse pattern (u PM ) would be induced, particularly in the form of arising from the synchronous basic pulse pattern (u PM ) resulting, offline pre-calculated current harmonics, Determining (S122c) a target stator current profile as a function of the current harmonic (i harm ), in particular by adding the reference waveform of the fundamental oscillation of the stator current (ifundref) and the current harmonics (i harm ), and Determine (S122d) the synchronous pulse pattern used to control the electrical machine (1) (u SPM ) depending on the course of the stator current flowing through the multitude of phase windings (i ist ), the specified target stator current profile and the synchronous base pulse pattern (u PM ). [5] Method according to claim 4, wherein determining (S122d) the synchronous pulse pattern used to control the electrical machine (1) (u SPM ) depending on the course of the stator current flowing through the multitude of phase windings (i ist ), the specified target stator current profile and the synchronous base pulse pattern (u PM ) includes: Changing the synchronous basic pulse pattern (u PM ) specified switching times of the converter circuit (20) depending on a deviation between the stator current flowing through the plurality of phase windings (i ist ) and the specified target curve of the stator current, to ensure a synchronous pulse pattern (u SPM ) to determine. [6] Method according to one of claims 3 to 5, wherein (S121) is used to determine the reference waveform of the fundamental oscillation of the stator current. (ifundref) and the reference curve of the fundamental frequency of the stator voltage (ufundref) an optimization problem is solved. [7] Method according to claim 6, wherein in the optimization problem a cost function is minimized which includes both an amount of deviation between a maximum achievable torque of the electric machine and the torque to be provided and the amount of the stator current, in particular wherein the maximum achievable torque of the electric machine (1) is a function of the reference response of the fundamental frequency (ifundref) of the stator current and the electric angular velocity of the electric machine (1). [8] Method according to claim 7, wherein the optimization problem must further satisfy that - a change in the stator current over time is zero and / or - an amount of the amplitude of the reference waveform of the fundamental oscillation of the stator current (ifundref) less than or equal to the magnitude of a maximum stator current and the magnitude of the amplitude of the reference waveform of the fundamental oscillation of the stator voltage (ufundref) less than or equal to the amount of a maximum stator voltage. [9] Method according to one of the preceding claims, wherein the detection (S100) of the course of the stator voltage applied to the plurality of phase windings (u ist ) and the course of the stator current flowing through the multitude of phase windings (i ist ) includes: Receiving (S101) a synchronous pulse pattern used to control the electric machine (1) (u SPM ), and Determine (S102) the stator voltage applied to the multitude of phase windings based on the received synchronous pulse pattern (u SPM ), in particular by determining the value of the stator voltage at a given time as the average value over a sampling period of the received synchronous pulse pattern containing that time (u SPM ). [10] Method according to one of the preceding claims, wherein the detection (S100) of the course of the stator voltage applied to the plurality of phase windings (u ist ) and the course of the stator current flowing through the multitude of phase windings (i ist ) includes: Measuring (S103) the course of the stator current flowing through the multitude of phase windings (i ist ) by means of one or more current sensors, wherein one or more current sensors are arranged between the power converter circuit (20) and one of the plurality of phase windings. [11] Computing unit (10) configured to perform all process steps of a process according to any of the preceding claims. [12] Drive unit (100) comprising an electric machine (1), a power converter circuit (20) comprising at least one half-bridge with a first controllable semiconductor switching element and a second controllable semiconductor switching element, and a computing unit (10) according to claim 11. [13] Computer program that causes a computing unit (10) to perform all the process steps of a method according to any one of claims 1 to 10 when executed on the computing unit. [14] Machine-readable storage medium with a computer program stored thereon according to claim 13.

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