EP4208942A1

EP4208942A1 - Method for modulating the torque ripple and/or the radial force of a three-phase current-operated electric machine

Info

Publication number: EP4208942A1
Application number: EP21762595.3A
Authority: EP
Inventors: Andreas LANGHECK; Dominik Stretz
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2020-09-04
Filing date: 2021-08-10
Publication date: 2023-07-12
Also published as: DE102020122099A1; WO2022048704A1; US20230336107A1; CN116034537A

Abstract

The invention relates to a method for modulating the torque ripple and/or the radial force of a three-phase current-operated electric machine (10), in particular of an electric drive machine of a motor vehicle able to be driven by an electric motor, comprising the following method steps: - selecting at least one harmonic (HM1_EM) in the torque of the electric machine (10) and/or selecting at least one harmonic (HM_X) of a load (20) coupled to the electric machine (10), wherein the at least one selected harmonic (HM1_EM, HM_X) is modulated by applying the at least one selected harmonic (HM1_EM, HM_X) to the d-current and/or q-current or to a variable correlated therewith in order to generate a setpoint variable (w) for driving the electric machine (10), wherein the phase angle of the harmonic in the d-current (Id) and/or of the harmonic in the q-current (Iq) with respect to the rotor angle is at least temporarily set to be different.

Description

Method for modulating the torque ripple and/or the radial force of a three-phase electric machine

The present invention relates to a method for modulating the torque ripple and/or the radial force of a three-phase electric machine, in particular an electric drive machine of a motor vehicle that can be driven by an electric motor, comprising the method steps: selection of at least one harmonic in the torque of the electric machine and/or selection of at least one Harmonics of a component coupled to the electrical machine.

DE 10 2014 208 384 A1 discloses a method for reducing gear meshing noise of an electrically drivable drive train with a toothed gear and an electric motor. The method comprises the steps of: determining an operating state of the drive train (10), reading out a data set assigned to the determined operating state from a data memory, and adjusting a torque of the electric motor according to the data set. It is proposed to apply a torque signal to the gearbox, which counteracts the vibration or the noise of the gearbox. The compensation torque signal is added to other desired torques, such as a static drive torque.

DE 10 2014 007 502 A1 discloses a method for noise modulation of an electric motor, the electric motor being a three-phase synchronous motor which is driven using vector control by means of a motor control unit, actual values for the rotated current components id and iq being obtained in a controlled system , where id dem Magnetizing current and iq correspond to the torque-forming current of the synchronous motor, and the actual values are compared with specified reference variables (iq_soll, id_soll). The differences between the actual values and the reference variables are converted into manipulated variables via a first controller and a first transformation stage in a duty cycle for a PWM generator in order to convert the actual values (iq, id) to the reference variables (iq_soll, id_soll ) to regulate. In addition, the current component (id) forming the magnetizing current is adjusted to a desired acoustic state by means of an acoustic regulator, depending on an acoustic state that was measured by a measuring device and forwarded to the engine control unit by means of a signal output.

Furthermore, DE 10 2009 000 928 A1 describes a method for reducing torque ripple in an electric motor. The method includes receiving a torque command and determining a cancellation current command based on the torque command. The method further includes generating a harmonic cancellation command based on the cancellation current command, wherein the harmonic cancellation command compensates for phase shift and damping induced by the current regulated control module, and wherein the current regulated control module is coupled to an inverter that is connected to the Electric motor is coupled. The method further includes providing the harmonics cancellation command to the current regulation module, wherein the current regulation module is configured to control the inverter in response to the harmonics cancellation command and the torque command.

The object of the invention is to provide a method for modulating the torque ripple and/or the radial force of a three-phase electric machine which is improved with regard to the variety of modulations. Advantageously, a method is to be provided which, in comparison to methods known from the prior art, reduces the torque ripple or the radial forces that occur in an electric drive machine in a drive train of an electrically operable Reduced motor vehicle and thus noise emissions in the vehicle further reduced.

This object is achieved by a method for modulating the torque ripple and/or the radial force of a three-phase electric machine with the features of patent claim 1. The method according to the invention comprises the method steps for this:

Selection of at least one harmonic in the torque of the electric machine and/or selection of at least one harmonic of a component of the drive train of the motor vehicle coupled to the electric machine. According to the invention, the at least one selected harmonic is modulated by impressing the at least one selected harmonic on the d-current and/or q-current or on a variable that correlates therewith, such as the stator voltage of the electrical machine or the magnetic flux within the electrical machine Generation of a target value for the activation of the electrical machine, the phase angle of the harmonic of the d-current and/or the phase angle of the harmonic of the q-current being set differently from the rotor angle at least temporarily, so that the phase angle of the d-component is at least temporarily unequal to the is the phase angle of the q-component. As a result, the bandwidth of the variety of modulations for influencing vibrations and/or noises generated by the electric machine or by components in the drive train of the motor vehicle is considerably increased and the possibilities for corresponding influencing are thus improved.

The method according to the invention thus specifically reduces harmonics in the torque of the electrical machine or in the drive train and thus vibrations and noises by impressing harmonics on the d-current or the q-current. Instead of reducing harmonics, however, they can also simply be adapted to the desired specifications. This current can be represented with amplitude and phase:

Further advantageous refinements of the invention are specified in the dependently formulated claims. The features listed individually in the dependent claims can be combined with one another in a technologically meaningful manner and can define further refinements of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, with further preferred configurations of the invention being presented.

According to an advantageous embodiment of the invention, it can be provided that the selection of at least one harmonic in the torque of the electric machine and/or the selection of at least one harmonic of a component coupled to the electric machine and the modulation of the at least one selected harmonic by impressing the at least one selected harmonics on the d-current and/or q-current or on a variable correlating thereto for controlling the electric machine with the proviso that the torque of the electric machine and/or the torque of the drive train is smoothed, so that vibrations and noises be reduced. From all possible combinations of d-current and q-current that specifically reduce harmonics in the torque, there are those that result in the lowest current amplitude, voltage amplitude, loss amplitude, etc. This achieves the advantage that the torque of the electrical machine or of the drive train connected to the electrical machine can be smoothed out, so that undesired vibrations and noise can be dampened in a significantly improved manner. According to a further preferred development of the invention, it can also be provided that the d-current and/or the q-current are selected in such a way that the magnitude of the resulting stator voltage or the magnitude of the resulting stator current be minimized, where the d-component of the stator voltage results in: and where the q-component of the stator voltage is given is.

The magnitude of the induced voltage is dependent on the speed of the electrical machine and the change in the magnetic flux in the same.

the torque

The electrical machine is in turn dependent on the magnetic flux as well as the current in the D direction and the current in the q direction. This results in a significantly increased number of combinations which, in addition to the torque of the electrical machine through i _d1 and i _q1 , impose an additional torque through i _dk and i _qk (M _k ). Here, the current for the torque M _k by the previously degrees of freedom described are selected so that it satisfies additional conditions, such as minimum magnitude of the stator voltage amplitude or minimum magnitude of the stator current amplitude or the like. This has the advantage that a smaller voltage space vector (due to the minimization of the stator voltage amplitude) also allows the electrical machine to be operated close to the voltage limits - for example in the area of the lower voltage limit when the battery is already relatively empty - or in the area of the upper one Voltage limit when the electric machine is to be operated under full load for acceleration.

Furthermore, according to a likewise advantageous embodiment of the invention, provision can be made for generating the setpoint variable

- a harmonic is calculated by performing the following process steps:

- Modeling of the torque or the radial force or a resulting vibration of the electrical machine with the aim of minimizing the torque ripple taking into account the induced voltage and/or the radial forces or with the aim of minimizing the radial forces taking the induced voltage into account, and

- generation of torque ripples and/or radial forces taking into account the induced stress, and

- Modeling of the induced stress considering the torque ripple and/or the radial forces.

According to a further particularly preferred embodiment of the invention, it can be provided that the d-current, the q-current and the d-phase angle and the q-phase angle are read out from a table to generate a setpoint variable for the activation of the electrical machine.

Advantageously, sizes can be read from four different tables to generate a setpoint for the control of the electrical machine, two of the tables each containing amplitudes of d sizes and q sizes and two other tables each containing the associated phases of the d sizes and of q-sizes. As an alternative to this, provision can also be made for generating a setpoint variable for controlling the electrical machine Sizes can be read from four different tables, two of the tables each containing real amplitude values of d-sizes and q-sizes and two further tables each containing imaginary amplitude values of the d-sizes and q-sizes. A further possibility for generating a setpoint variable for the activation of the electrical machine is that variables are read out from a table, in particular containing exclusively amplitude variables, with further required variables being determined according to a predetermined rule.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be pointed out that the invention should not be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description and/or figures. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. The same reference symbols designate the same objects, so that explanations from other figures can be used as a supplement if necessary.

Show it:

Figure 1 shows the drive train of an electrically driven motor vehicle in a block diagram in a schematic representation,

Figure 2 in the upper representation, the torque curve of an electric machine with three different control methods, and in the lower representation, the voltage curves associated with the torque curves shown in Figure 2 above at the stator of the correspondingly controlled electric machine, FIG. 3 shows the block diagram of the control and regulation unit from FIG. 1 in a more detailed representation,

FIG. 4 shows the block diagram of the setpoint generator from FIG. 1 in a more detailed representation,

FIG. 5 shows the block diagram of the harmonics from FIG. 4 according to the prior art and according to the invention in a comparison, and

FIG. 6 shows the block diagram of the setpoint generator from FIG. 4 in an expanded representation.

FIG. 1 shows the drive train 100 of an electrically driven motor vehicle in a block diagram in a schematic representation. The electrical machine 10 is mechanically coupled on the output side to a load 20, such as the drive axle of a motor vehicle. On the input side, the electrical machine 10 is controlled by power electronics 30 which, for example, supplies the stator windings of the electrical machine 10 with three-phase current. For this purpose, the power electronics are connected to an energy source 40, such as the on-board power supply battery of the motor vehicle, with the direct voltage or direct current supplied by the battery being connected via corresponding

Inverter of the power electronics 30 is converted according to three-phase current. The power electronics 30 is connected to a control/regulating unit 50 via a further input-side interface, which controls the power electronics in accordance with the setpoint specifications of a setpoint generator 60 connected to the input side. The control / regulation unit 50 is optionally via appropriate sensors with for the control of the electrical machine 10 important operating variables of the electrical machine 10, by the electrical Load 20 driven by the machine 10 and by the energy source 40 supplying the power electronics 30 or the electric machine 10 .

In the upper illustration, FIG. 2 shows the torque curve of an electric machine 10 with three different control methods. The first torque curve M1 (solid line) shows the torque that occurs when the electrical machine 10 is controlled with sinusoidal excitation without harmonic components according to the prior art. The second torque curve M2 (dash-dotted line) shows the torque curve that occurs with sinusoidal excitation with standard-harmonic components according to the prior art. Finally, the remaining third torque curve M3 (dotted line) shows, in comparison to this, the torque curve that occurs with sinusoidal excitation with harmonic components according to the invention, the d-sizes and/or the q-sizes having a phase angle that differs at least at times is to the rotor angle. In the lower representation, FIG. 2 shows the voltage curves associated with the torque curves shown in FIG Excitation without harmonic components according to the prior art. The second voltage profile U2 (dash-dotted line) shows the voltage profile that occurs in the case of sinusoidal excitation with standard-harmonic components according to the prior art. Finally, the remaining third voltage curve U3 (dotted line) shows, in comparison to this, the voltage curve that occurs with sinusoidal excitation with harmonic components according to the invention, with the d values and/or the q values having a phase angle that differs at least temporarily is to the rotor angle. The example shown clearly shows that the same torque can be provided with the method according to the invention as with conventional methods, with a significantly lower stress amplitude being required. FIG. 3 shows the block diagram of the control/regulation unit 50 from FIG. 1 in a more detailed representation. The control/regulation unit 50 is shown with its static input variables of d current and q current I _d0 and l _q0 and with the dynamic d and q input variables I _dk (Υ) and I _{dq that change as a function} of the rotor angle (y). The setpoint values U _a , _b , _c for controlling the power electronics 30 are shown on the output side. A setpoint/actual value comparison and the corresponding control are possible either with an additive component - or by filtering out the dynamic part in the setpoint/actual value comparison and adding it up again during the subsequent adjustment process (so-called blind addition of the dynamic part as voltage).

FIG. 4 shows the block diagram of setpoint generator 60 for specifying setpoint values to control/regulating unit 50 from FIG. 1 in a more detailed representation. The setpoint generator 60 shown provides the input variables for the control/regulation unit 50 that have already been explained above with regard to FIG. These are generated by modeling a torque request through a torque part 61 selecting a harmonic H _{M 1_EM} in the torque of the electric machine 10 and/or harmonics H _{M_X} of a powertrain load 20 coupled to the electric machine 10 . The at least one selected harmonic H _{M 1_EM} , H _{M_X} is then modulated by impressing the at least one selected harmonic H _{M 1_EM} , H _{M_X} on the d-current and/or on the q-current to generate a setpoint value w for controlling the Electrical machine 10. The phase angle φ _d,k , φ _q,k of the harmonics H _ld in the d-current Id and/or the harmonics H _lq in the q-current Iq is at least temporarily set differently to the rotor angle (y), so that φ _d,k ≠ φ _q,k . The phase angle (relative to the rotor angle) of the current (Id, Iq) can thus be set independently of Id and Iq, so that it can be set differently if it is advantageous.

The calculation strategy on which the harmonic part 62 is based includes at least the following parts:

- modulation of torque and/or radial forces,

- minimizing the torque ripple considering the induced stress and/or the radial forces, - Minimization of the radial forces taking into account the torque ripple and/or the induced stress,

- generation of torque ripples and/or radial forces taking into account the induced stress,

- Modulation of the induced voltage taking into account the torque ripple and/or the radial forces.

The harmonic part 62 optionally receives input variables from the outside in the form of a ripple request and from the inside, from the torque part 61 . On the output side, both the static variables as input variables for the control/regulation unit 50 and the dynamic variables as input variables for the control/regulation unit 50 are then provided by the setpoint generator 60 through the torque part 61 .

FIG. 5 shows the block diagram of the harmonic part 62 from FIG. 4 according to the prior art (above) and according to the invention (below) in a comparison. It is easy to see that, according to the invention, the phase angles of the d-current and q-current are fundamentally different.

FIG. 6 shows the block diagram of setpoint generator 60 from FIG. 4 in an expanded representation. The representation of setpoint generator 60 already shown and explained in FIG the d-phase angle φ _d,k and the q-phase angle φ _q,k can be read from a table.

To generate a target variable w for the control of the electrical machine 10, variables can be read from four different tables, two of the tables each containing amplitudes of d variables and q variables, and two other tables each containing the associated phases of the d variables and of q-sizes. Alternatively, it is provided that, in order to generate a setpoint variable for the control of the electrical machine, variables are read from four different tables, two of the tables each containing real amplitude values of d variables and q variables and two further tables each containing imaginary amplitude values of the d sizes and the q sizes include. Finally, in order to generate a target variable for the activation of the electrical machine, variables can be read from a table that in particular contains only amplitude variables, with further required variables being determined according to a predetermined specification.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered as limiting but as illustrative. The following patent claims are to be understood in such a way that a mentioned feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' feature, this designation serves to distinguish between two features of the same type, without establishing a ranking.

Reference character list

10 electric machine

20 load (drive train) 30 power electronics

40 battery/power source

50 control unit

60 setpoint adjusters

61 torque part 62 harmonic part

63 table part

100 powertrain

Claims

Claims 1. A method for modulating the torque ripple and/or the radial force of a three-phase electric machine (10), in particular an electric drive machine of a drive train (100) of a motor vehicle that can be driven by an electric motor, comprising the method steps:

- Selection of at least one harmonic (H _{M 1_EM} ) in the torque of the electric machine (10) and/or selection of at least one harmonic (H _{M_X} ) of a load (20) of the drive train (100) coupled to the electric machine (10), characterized in that

- Modulation of the at least one selected harmonic (H _{M 1_EM} , H _{M_X} ) by impressing the at least one selected harmonic (H _{M 1_EM} , H _{M_X} ) on the d-current and/or q-current or on a variable correlating therewith to generate a Setpoint () for the control of the electrical machine (1), the phase angle (φ _d,k , φ _q,k ) of the harmonics (H _ld ) in the d-current (Id) and/or the harmonics (H _lq ) in the q-current (Iq) to the rotor angle () is at least temporarily set differently, so that φ _d,k ≠ φ _q,k .

2. The method according to claim 1, characterized in that

- the selection of at least one harmonic (H _{DM_EM} ) in the torque of the electric machine (10) and/or the selection of at least one harmonic (H _{DM_X} ) of a load (20) of the drive train (100) coupled to the electric machine (10), and the modulation of the at least one selected harmonic (H _{DM_EM} , H _{DM_X} ) by impressing the at least one selected harmonic (H) on the d-current (Id) and/or q-current (Iq) or on a variable correlating therewith for control of the electrical machine (10) with the proviso that the torque of the electrical machine (10) and/or the Torque of the drive train (100) is smoothed so that vibration and noise are reduced.

3. The method according to any one of the preceding claims, characterized in that the d-current (Id) and / or the q-current (Iq) are selected so that the amount of the resulting stator voltage or the magnitude of the resulting stator current be minimized, where and is.

4. The method according to any one of the preceding claims, characterized in that for the generation of the target variable (w)

- a harmonic is calculated by performing the following process steps:

- Modeling the torque of the electrical machine (10) with the aim of minimizing the torque ripple taking into account the induced voltage and / or the radial forces or with the aim of Minimizing the radial forces taking into account the induced stress, and

5. The method according to any one of the preceding claims, characterized in that to generate a target variable (w) for controlling the electrical machine (1) of the d-current (Id), the q-current (Iq) and the d-phase angle

( φ _d,k ) and the q-phase angle ( φ _q,k ) can be read from a table.

6. The method according to claim 5, characterized in that to generate a target variable (w) for the control of the electrical machine sizes are read from four different tables, two of the tables each contain amplitudes of d-sizes and q-sizes and two further tables each contain the associated phases ( φ _d,k , φ _q,k ) of the d-values and the q-values.

7. The method according to claim 5, characterized in that to generate a target variable (w) for controlling the electrical machine, variables are read from four different tables, two of the tables each containing real amplitude values of d variables and q variables and where two further tables each contain imaginary amplitude values of the d-values and the q-values.

8. The method according to claim 5, characterized in that - 17 - to generate a target variable (w) for the control of the electrical machine, variables can be read from a table that in particular only contains amplitude variables, with further required variables being determined according to a predetermined rule.