Method for controlling an electrical machine and drive unit

Abstract

The invention relates to a method for controlling an electrical machine (1) comprising a stator (1d) with a stator winding and a rotor (1a). In the method, an electrical position angle signal of the rotor (1a) and a vibration signal are detected (S100), and a possible mechanical angular position of the rotor (1a) is determined (S110). Subsequently, using the vibration signal, it is determined (S120) whether the possible mechanical angular position of the rotor (1a) corresponds to an actual mechanical angular position of the rotor (1a), and the possible mechanical angular position of the rotor (1a) is corrected (S130) using the electrical position angle signal of the rotor (1a) if it is determined that the possible mechanical angular position of the rotor (1a) does not correspond to the actual mechanical angular position of the rotor (1a).The invention further relates to a computing unit (10) designed to carry out the method and a drive unit (100).

Description

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

[0002] In rotating field machines, such as squirrel-cage asynchronous machines (SCMs) or permanent magnet synchronous machines (PCMs), the precise angular position of the rotor's magnetic field is required for operation with field-oriented control. Various types of encoders can be used to determine this position. Using high-resolution optical encoders, the absolute angle can be determined very precisely. The high resolution of such encoders enables a sufficiently good resolution of the field position even with a large number of pole pairs. The disadvantage of such encoders is that they are often very expensive and also very sensitive.

[0003] In the traction drives of electric vehicles, much cheaper and more robust sensors, such as resolvers, are conventionally used, although these have a significantly lower resolution. The resolution for field-oriented control can be increased easily and cost-effectively by increasing the number of pole pairs of the resolver, thereby increasing the rotor position resolution by a factor of the number of pole pairs. However, in electrical machines with a number of pole pairs greater than one, the mechanical position angle can no longer be clearly assigned to the measured electrical position angle. This does not affect classic field-oriented control, however, because the machine is symmetrical with the electrical position angle. However, there are also applications for which the mechanical position angle is crucial and the use of the incorrect mechanical position angle must be avoided due to the ambiguity.Such applications include, for example, positioning functions such as the synchronization of clutches in transmissions, the synchronized engagement of rotor locks or NVH (noise, vibration, and harshness) damping algorithms for attached compressors or transmissions. Disclosure of the invention

[0004] According to the invention, a method for controlling an electrical machine, a computing unit and a computer program for implementing the method, and a drive unit with the features of the independent patent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

[0005] The invention is based on an electrical machine having a stator with a stator winding and a rotor, in which the electrical position angle of the rotor of the electrical machine is detected. To detect the electrical position angle of the electrical machine, the electrical machine comprises, in particular, a position sensor configured to detect the electrical position angle and having a pole pair number greater than one. Alternatively or additionally, the electrical position angle can also be estimated based on "asymmetries" of the electromagnetic field of the electrical machine, for example, based on the inductances in the d- and q-direction of the electrical machine.

[0006] When the electrical machine is in operation, mechanical vibrations are generated which also exhibit “asymmetries”. The origin of these oscillations or vibrations will be briefly discussed here using a gearbox as an example. When two gears in a transmission gear stage mesh, the tooth stiffness changes depending on the position, i.e. from the initial engagement of the teeth until the engagement is released, which causes the two gears to vibrate against each other. This vibration is in turn transmitted via axles and bearings to the gearbox housing and can be measured, for example, by an acceleration sensor arranged on the gearbox housing or a housing of the electrical machine. The position-dependent vibrations are based on the tooth mesh and occur when the two gears rotate, as they are caused by the angle-dependent change in torsional stiffness.One gear of the gearbox is fixed to the rotor shaft of the electric machine, whereby the mechanical position of the oscillation is firmly correlated with the mechanical position of the rotor, and thus also with the position detection of the rotor. The frequency of the oscillation between the gears is the frequency of the tooth mesh, i.e. it corresponds to the mechanical rotor speed multiplied by the number of teeth on the gear connected to the rotor shaft. If the number of teeth on this gear is odd, which can be achieved by design, the mechanical position, i.e. the mechanical position angle, can always be uniquely determined in relation to the electrical position angle, since the electrical position angle is always an even multiple of the mechanical angular position.

[0007] The core of the invention is to use the mechanical "asymmetries" in a vibration signal to resolve the ambiguity of the electrical position angle, which is estimated or measured by a position sensor, at system start-up. In general, vibrations occurring in electric machines used as traction drives, e.g., due to the gear mesh frequency, are evident at almost all measuring points on the transmission or electric machine.

[0008] The method makes it possible to easily and correctly determine the mechanical position angle.

[0009] Because the number of possible mechanical position angles for a given electrical position angle corresponds to the number of pole pairs, the solution space to be searched is discrete and small, so that the mechanical position angle can be determined robustly and with little computational effort.

[0010] Furthermore, if gear meshing noise of a gear is used as a mechanical anomaly measured by the acceleration sensor, the mechanical attitude angle can be determined with a low error rate because the signal is clearly present in each gear at a suitable speed.

[0011] By precisely determining the mechanical attitude angle, the use of transmission NVH damping techniques is enabled, which, for example, increases the comfort of vehicle occupants when the electric machine is used as a drive in a vehicle.

[0012] Furthermore, the synchronization of transmission-integrated (claw) clutches, e.g. for decoupling units or gearshift stages, is enabled.

[0013] The method is advantageously carried out at an essentially constant speed greater than zero. Essentially constant means that the speed can fluctuate within certain unavoidable fluctuations, e.g., by a few percent. It is also possible to operate at a constant acceleration, since the constant acceleration and the resulting change in the vibration signal can be calculated from the vibration signal with minimal computational effort. Furthermore, operation at a speed greater than zero ensures that vibrations are generated, and therefore a vibration signal can be measured.

[0014] Specifically, an electrical position angle signal of the rotor and a vibration signal are acquired. Subsequently, a possible mechanical angular position of the rotor is determined using the electrical position angle signal. As explained, only a few discrete values ​​are possible here. Subsequently, the vibration signal is used to determine whether the possible mechanical angular position of the rotor corresponds to the actual mechanical angular position of the rotor. If it is determined that the possible mechanical angular position of the rotor does not correspond to the actual mechanical angular position of the rotor, the possible mechanical angular position of the rotor is corrected using the electrical position angle signal of the rotor.

[0015] If there are more than two discrete values ​​for the possible mechanical angular position of the rotor, the method is then expediently carried out a second time to determine whether the corrected mechanical position angle corresponds to the actual mechanical position of the rotor of the electrical machine.

[0016] This allows the aforementioned advantages to be achieved with little computational effort.

[0017] In one embodiment, the electric machine further comprises a position sensor, in particular a resolver, which is configured to detect an electrical position angle of the electric machine and generate the electrical position angle signal. A pole pair number of the position sensor is greater than one and corresponds in particular to a pole pair number of the rotor.

[0018] For the method, advantageous position sensors can be used, whereby the absolute and correct mechanical position angle can still be reliably determined by means of the invention.

[0019] In one embodiment, in which in particular no position sensor is required, the electrical position angle is estimated as a function of asymmetries in the electric field of the electrical machine. For example, the electrical position angle can be estimated based on asymmetries of the inductances in the d and q directions. For example, at low speed of the rotor of the electrical machine, test pulses can be impressed on the voltage applied to the stator, and the electrical position angle of the rotor can be determined based on the reaction of the stator current. Since the inductances or saturation are different in the d and q directions, different current rise rates or final current values ​​result depending on the direction when a test pulse is impressed on the voltage. Alternatively, at high speeds, the angle of the counter voltage can be determined based on a measurement or estimate of the counter voltage.

[0020] This means that the mechanical position angle can also be determined reliably and correctly if the electrical position angle of the electrical machine is measured without sensors when the number of pole pairs of the electrical machine is known, which means that the method can be implemented particularly cost-effectively.

[0021] In one embodiment, the vibration signal is measured by an acceleration sensor arranged on the electric machine or on a component connected to the electric machine, for example, a transmission or an inverter, and configured to measure vibrations of the electric machine or the component connected to the electric machine. The acceleration sensor is, in particular, a MEMS sensor.

[0022] If an acceleration sensor is already installed for other applications, using it to determine the actual mechanical angular position of the rotor can save costs for additional components and also allow the method to be transferred to existing electrical machines.

[0023] Furthermore, MEMS sensors are cost-effective sensors for determining vibrations of components, so that the actual mechanical angular position of the rotor can be determined reliably and accurately in a cost-effective manner.

[0024] In one embodiment, the possible mechanical angular position of the rotor is determined as a function of a reference position in the electrical position angle signal or of a stored mechanical angular position. The reference position can, for example, be a zero crossing of the electrical position angle signal. The possible mechanical angular position can correspond to the actual mechanical angular position of the rotor or be shifted by one or more period lengths of the electrical position angle signal relative to the actual mechanical angular position of the rotor. The stored mechanical angular position can, in particular, be stored in a memory of a computing unit that carries out the method.The stored mechanical angular position is, for example, an actual mechanical angular position determined during a previous execution of the method and subsequently stored in memory, for example, the angular position when the electric machine is switched off or stopped. The stored mechanical angular position typically corresponds to the actual mechanical angular position, unless the electric machine was moved externally while the machine control or position detection was not in operation, for example, because the electric vehicle in which the electric machine is installed was towed or moved.

[0025] In one embodiment, the possible mechanical angular position of the rotor is corrected by shifting the possible mechanical angular position of the rotor by one period of the electrical position angle signal. The mechanical angular position of the rotor is directly correlated with the number of pole pairs of the rotor and the position sensor, if used, and the electrical position angle is always an integer multiple of the mechanical angular position. The corrected possible mechanical angular position of the rotor is then stored and used in the future as the possible mechanical angular position of the rotor.

[0026] This makes it easy to determine the actual mechanical angular position of the rotor.

[0027] In one embodiment, determining whether the possible mechanical angular position of the rotor corresponds to the actual mechanical angular position of the rotor comprises determining a phase shift between the vibration signal and the possible mechanical angular position of the rotor. For this purpose, the vibration signal can be subjected to a (fast) Fourier transformation, in particular using a noise frequency or tooth meshing frequency estimated from the electrical position angle signal, in order to determine a fundamental vibration. If the possible mechanical angular position corresponds to the actual mechanical angular position, the phase shift between the vibration signal and the possible mechanical angular position corresponds to a predefined or predetermined value. This will be briefly explained using the example of a transmission with one gear stage.The vibrations of the gears relative to each other depend on the relative position of the teeth of the two gears involved. At a constant speed of the electric machine, the phase shift between the actual mechanical angular position and the vibration signal is known, since the phase shift depends only on the mechanical structure and is constant for a positive connection between the rotor, position sensor and gear. The value of the phase shift can therefore be determined once for the design and then used for all identical axes. It is then determined that the possible mechanical angular position corresponds to the actual mechanical angular position of the rotor if the determined phase shift corresponds to the specified value, and that the possible mechanical angular position does not correspond to the actual mechanical angular position of the rotor if the determined phase shift does not correspond to the specified value.The phase shift doesn't necessarily have to be the exact value, but can also be within a range of a few percent. This allows, for example, aging processes of mechanical components to be taken into account.

[0028] Alternatively or additionally, determining the phase shift between the vibration signal and the possible mechanical angular position of the rotor may comprise measuring the phase shift in the time domain.

[0029] Alternatively or additionally, determining the phase shift between the vibration signal and the possible mechanical angular position of the rotor may include adjusting and thereby determining the phase shift via a phase-locked loop (PLL).

[0030] Using each of these approaches, the actual mechanical angular position of the rotor can be determined in a simple manner and with little computational effort.

[0031] In one embodiment, the electric machine further comprises harmonic control. The harmonic control is configured to determine a damping signal, depending on the vibration signal and the possible mechanical angular position of the rotor, with which the vibrations can be reduced or damped. The determined damping signal can then be applied to the current supplied to the stator by controlling the inverter. For further details regarding the implementation and execution of harmonic control, see, for example,

[0032] DE 10 2023 207 191 or DE 10 2023 207 178. Determining whether the possible mechanical angular position of the rotor corresponds to the actual mechanical angular position of the rotor comprises determining, by means of harmonic control, a damping signal for damping the vibration signal and controlling the electrical machine using the damping signal. Subsequently, a second vibration signal is acquired, and the vibration signal acquired before the damping is compared with the second vibration signal. For this purpose, in particular, a noise frequency is estimated using the electrical position angle, a fast Fourier transform of the vibration signal and the second vibration signal is performed using the noise frequency, and an amplitude of the vibration signal is compared with an amplitude of the second vibration signal.If the possible mechanical angular position corresponds to the actual mechanical angular position, a damping signal is determined by the harmonic control and adjusted by the inverter. This means that the electric machine is controlled using the damping signal, which actually dampens the oscillations, thereby reducing the amplitude of the oscillation signal. However, if the possible mechanical angular position does not correspond to the actual mechanical angular position, a damping signal is still determined by the harmonic control and adjusted by the inverter. However, the oscillation is not dampened by this damping signal and can even be amplified, which means that the amplitude of the oscillation signal remains unchanged or increases.Therefore, it can be determined that the possible mechanical angular position of the rotor corresponds to the actual mechanical angular position of the rotor if the second vibration signal results in a damped vibration compared to the vibration signal, or that the possible mechanical angular position of the rotor does not correspond to the actual mechanical angular position of the rotor if the second vibration signal does not result in a damped vibration compared to the vibration signal.

[0033] In embodiments of the invention, it is determined that the second vibration signal results in a vibration that is damped compared to the vibration signal if, for the noise frequency, an amplitude of the second vibration signal is smaller than an amplitude of the vibration signal, and it is determined that the second vibration signal does not result in a vibration that is damped compared to the vibration signal if, for the noise frequency, the amplitude of the second vibration signal is greater than or equal to the amplitude of the vibration signal.

[0034] By using the harmonic control and the damping signal, the mechanical position angle can be determined easily, correctly and reliably.

[0035] A computing unit according to the invention, e.g. a control unit of an electric vehicle, is configured, in particular in terms of programming, to carry out a method according to the invention.

[0036] The implementation of 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, since this entails particularly low costs, in particular if an executing control unit is also used for other tasks and is therefore already present. Finally, a machine-readable storage medium is provided with a computer program stored thereon, as described above. Suitable storage media or data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, such as hard disks, flash memories, EEPROMs, DVDs, and others. Downloading a program via computer networks (Internet, intranet, etc.) is also possible. Such a download can be wired or cable-based or wireless (e.g. via a WLAN network, a 3G, 4G, 5G or 6G connection, etc.).

[0037] The invention further relates to a drive unit comprising an electrical machine with a stator with a stator winding and a rotor, an acceleration sensor which is configured to measure vibrations of the electrical machine or of a component connected to the electrical machine, an inverter which is configured to supply the stator of the electrical machine with current and a computing unit according to the invention.

[0038] Such a drive unit can achieve greater comfort for the vehicle occupants during operation of the electric machine, since noise emissions can be reduced due to the correctly determined mechanical position of the rotor.

[0039] Furthermore, the structure of the position measurement of the rotor of the electric machine can be optimized by merging the data from cost-effective sensors.

[0040] In one embodiment, the drive unit further comprises a transmission with a gear stage comprising at least two gears, wherein the acceleration sensor is arranged on the transmission and is configured to measure the vibrations of the transmission. The gear connected to the rotor of the electric machine has, in particular, an odd number of teeth.

[0041] This allows a sensor to be used in a simple and cost-effective manner to correctly determine the mechanical position of the rotor and to reduce the noise of the gearbox, which in particular can reduce costs.

[0042] In one embodiment, the drive unit further comprises a position sensor which is configured to detect an electrical position angle of the electrical machine, wherein in embodiments a number of pole pairs of the position sensor is greater than one and in particular corresponds to the number of pole pairs of the rotor.

[0043] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0044] The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing. Short description of the drawings Fig. 1 shows a drive unit according to an embodiment of the invention, Fig. 2a and Fig. 2b shows stiffness curves of a toothing of gears with tooth pair stiffness, tooth stiffness and the average tooth stiffness, Fig. 3 shows the course of the electrical and mechanical position angle as well as a tooth mesh position and a damping signal when the mechanical position angle is determined correctly, Fig. 4 shows the course of the electrical and mechanical position angle as well as a tooth meshing position and a damping signal when the mechanical position angle is not determined correctly, Fig. 5 shows a flowchart of an embodiment of the method according to the invention, and Fig. 6 shows a flowchart of another embodiment of the method according to the invention. Embodiments of the invention

[0045] Fig. 1 shows a drive unit 100 according to an embodiment of the invention. The drive unit 100 comprises an electric machine 1 with a stator 1d having a stator winding and a rotor 1a. The rotor 1a is connected via a rotor shaft 1b to a first gear 5a of a gear stage of a transmission 5. The gear stage further comprises a second gear 5b, which meshes with the first gear 5a and transmits the torque generated by the electric machine 1 via an output shaft 5c, for example, to the traction wheels of an electric vehicle in which the electric machine 1 is installed. Furthermore, a position sensor 2 is arranged on the rotor shaft 1b of the rotor 1a and is configured to detect the electrical position angle or an electrical position angle signal of the rotor 1a. The electrical position angle signal is fed to a computing unit 10 of the drive unit 100.An acceleration sensor 3 of the drive unit 100, which is in particular a MEMS sensor, is also arranged on the housing of the transmission 5. The acceleration sensor 3 is configured to measure the vibrations or oscillations of the transmission 5 and output the measured vibration signal to the computing unit 10. The stator 1d of the electric machine 1 is supplied with power and controlled by an inverter 6 of the drive unit 100.

[0046] Fig. 2a and Fig. 2b shows stiffness curves of a toothing of gears with tooth pair stiffness c z , Gear stiffness c ze and the average gear stiffness c zγ over the angle of rotation or the path of rotation while the gears rotate.

[0047] Fig. 2a shows the stiffness curve of the tooth spring stiffness c z and the gear stiffness c zeof two gears 5a, 5b, which have straight teeth, over the angle of rotation. It can be seen that the tooth spring stiffness c z during the rotational movement of the gears 5a, 5b from the average tooth stiffness c zγ during the meshing of the gears 5a, 5b in the positive and negative directions, whereby the deviations (hatched area) in the positive and negative directions are asymmetrical. The tooth spring stiffness c, which varies with the angle of rotation, z of the gears 5a, 5b leads to vibrations being generated in the gear 5, which are transmitted to the gear housing and can therefore be measured by an acceleration sensor 3. The asymmetrical deviation of the tooth spring stiffness c z of the average gear stiffness c zγis also present in the vibration signal measured by the acceleration sensor 3, whereby the vibration signal can be directly correlated with the rotational state of the gears 5a, 5b and thus with the rotational state of the rotor 1a.

[0048] Fig. 2b shows the stiffness curve of the tooth spring stiffness c z and the gear stiffness c ze of two gears 5a, 5b, which have helical teeth, over the angle of rotation. In contrast to spur gearing, the deviation (hatched area) of the tooth spring stiffness c z of the average gear stiffness c zγ lower. However, even with helical gearing, the deviation in the positive and negative directions is asymmetrical, so that the rotational state of the gears 5a, 5b and thus of the rotor 1a can be determined from the vibration or oscillation signal measured by the acceleration sensor 3.

[0049] Fig. 3 shows the curve 310 of the electrical position angle, i.e. the electrical position angle signal (dashed line, bottom graph), and one of the two possible mechanical angular positions (solid line 330, middle graph), at an essentially constant speed of the electrical machine 1. Fig. 4 shows the curve 310 of the electrical position angle and the other of the two possible mechanical angular positions (solid line 350, middle graph), at an essentially constant speed of the electrical machine 1. The position sensor 2, which measures the electrical position angle signal, has a pole pair number of two. This can be seen from the fact that the electrical position angle signal shows two revolutions (two sweeps from 0° to 360°), while the possible mechanical angular position shows one revolution (one sweep from 0° to 360°), i.e. the rotor 1a of the electrical machine 1 only performs one revolution, while the electrical position angle signal measures two revolutions.

[0050] Furthermore, in the Fig. 3 and Fig. 4 outlines two different embodiments for determining the actual mechanical angular position, ie which of 330 or 350 is correct, both methods evaluating a vibration signal.

[0051] A first method involves determining a vibration signal 340 for the tooth meshing frequency. This means that the vibration signal 340 for the tooth meshing frequency (dotted line, upper graph) is determined from a total measured vibration signal, e.g., using FFT. From the vibration signal 340, it can be seen that the gear 5a, which is connected to the rotor 1a of the electric machine 1 via the rotor shaft 1b, has, for example, three teeth, since three tooth meshes (three cycles of the tooth meshing position) occur during one revolution of the rotor 1a (one cycle through the possible mechanical angular position).

[0052] Subsequently, a phase shift is determined between the vibration signal 340 and the possible mechanical angular position 330 or 350 of the rotor 1a. In the example of Fig. 3 results in a phase shift of (approximately) zero, in the example of Fig. 4 of non-zero. The expected phase shift for the actual angular position is known in advance, so the correct possible mechanical angular position can be selected.

[0053] A second method uses a damping of the vibration signal by means of a damping signal 320 (dash-dot line, middle graph), which is determined by means of a harmonic control.

[0054] To determine whether the possible mechanical angular position corresponds to the actual mechanical angular position, the vibration signal is recorded. The damping signal is then determined and impressed on the current of the electrical machine 1 by the control of the inverter 6. A second vibration signal is then determined and compared with the previously recorded vibration signal. If the possible mechanical angular position does not correspond to the actual mechanical angular position, the oscillations or vibrations of the gears are not damped, so that for the tooth meshing frequency or noise frequency the amplitude of the second vibration signal is equal to or greater than the amplitude of the previously recorded vibration signal. If, on the other hand, the possible mechanical angular position corresponds to the actual mechanical angular position, the oscillations or vibrations are damped.Vibrations of the gears, so that for the tooth meshing frequency or noise frequency the amplitude of the second vibration signal is smaller than the amplitude of the previously recorded vibration signal.

[0055] Fig. Figure 5 shows a flowchart of an embodiment of the method according to the invention. The method can advantageously be carried out when the rotor 1a of the electric machine 1 is operated at a constant speed greater than zero.

[0056] In step S100, an electrical position angle signal of the rotor 1a and a vibration signal are detected by the computing unit 10. The electrical position angle signal can be estimated based on asymmetries in the electric field (sensorless determination) or measured by a position sensor 2 whose number of pole pairs is greater than one. An exemplary curve of the electrical position angle signal 310 for a resolver used as position sensor 2 with a number of pole pairs of two is shown in the Fig. 3 and Fig. 4 (dotted line). The vibration signal is measured by the acceleration sensor 3, for example a MEMS sensor, and output to the computing unit 10.

[0057] In step S110, the possible mechanical angular position of the rotor 1a is determined, for example as a function of a mechanical angular position stored in the memory of the computing unit 10 or as a function of a reference position, for example a zero crossing of the electrical position angle signal.

[0058] In step S120, it is determined using the vibration signal whether the possible mechanical angular position of the rotor 1a corresponds to the actual mechanical angular position of the rotor 1a.

[0059] For this purpose, a phase shift between the vibration signal and the possible mechanical angular position of the rotor 1a is determined in step S121a. To determine the phase shift, the vibration signal can, in particular, be subjected to a (fast) Fourier transformation, with a noise frequency or tooth meshing frequency estimated from the electrical position angle signal being used as the frequency for the Fourier transformation. Alternatively or additionally, the phase shift can also be measured in the time domain or adjusted via a PLL and thus determined, and then compared with the specified value.

[0060] Subsequently, in step S122a, it is determined that the possible mechanical angular position corresponds to an actual mechanical angular position of the rotor 1a if the determined phase shift corresponds to a predetermined value, or in step S123a, it is determined that the possible mechanical angular position does not correspond to the actual mechanical angular position of the rotor 1a if the determined phase shift does not correspond to the predetermined value.

[0061] Subsequently, in step S130, the possible mechanical angular position of the rotor 1a is corrected if it is determined in step S123a that the possible mechanical angular position does not correspond to the actual mechanical angular position of the rotor 1a.

[0062] To do this, the possible mechanical angular position is shifted by one period of the electrical position angle signal in step S131. Since, as previously described, the frequency of the electrical position angle signal is a multiple of the frequency of the mechanical position angle, the actual mechanical angular position can be determined after a number of iterations. The maximum number of iterations corresponds to the number of pole pairs of position sensor 2.

[0063] Fig. Figure 6 shows a flow chart of another embodiment of the method according to the invention. To carry out the Fig. In the method illustrated in Figure 6, the electric machine has harmonic control. The harmonic control can, for example, be part of the computing unit 10.

[0064] As in the Fig.In the method shown in Figure 5, an electrical position angle signal of the rotor 1a and a vibration signal are detected by the computing unit 10 in step S100 and the possible mechanical angular position of the rotor 1a is determined in step S110.

[0065] In step S120, it is again determined using the vibration signal whether the possible mechanical angular position of the rotor 1a corresponds to an actual mechanical angular position of the rotor 1a.

[0066] For this purpose, in step S121b, the harmonic control determines a damping signal 320 to dampen the vibration signal. The damping signal is determined depending on the vibration signal and the possible mechanical angular position of the rotor.

[0067] In step S122b, the electric machine 1 is controlled using the damping signal. For this purpose, the stator 1d is supplied with a current from the inverter 6, which is imprinted with the damping signal. This produces a corresponding torque signal on the rotor 1a.

[0068] Subsequently, in step S123b, a second vibration signal is acquired. If the damping signal was determined based on the actual mechanical angular position, i.e., if the possible mechanical angular position corresponds to the actual mechanical angular position, the vibrations are damped. However, if the possible mechanical angular position does not correspond to the actual mechanical angular position, optimal damping of the vibrations is not achieved. For example, the vibrations may be only weakly damped or may even be excited.

[0069] In step S124b, the vibration signal and the second vibration signal are compared. Specifically, a noise frequency is estimated using the electrical attitude angle, a fast Fourier transform of the vibration signal and the second vibration signal is performed using the noise frequency, and an amplitude of the transformed second vibration signal and an amplitude of the vibration signal are compared.

[0070] Subsequently, in step S125b, it is determined whether the possible mechanical angular position of the rotor 1a corresponds to the actual mechanical angular position of the rotor 1a. It is determined that the possible mechanical angular position of the rotor 1a corresponds to the actual mechanical angular position of the rotor 1a if the second oscillation signal results in a well-damped oscillation compared to the oscillation signal, or it is determined that the possible mechanical angular position of the rotor 1a does not correspond to the actual mechanical angular position of the rotor 1a if the second oscillation signal does not result in a well-damped oscillation compared to the oscillation signal.The second oscillation signal results, for example, in a damped oscillation if the amplitude of the transformed second oscillation signal is significantly smaller than the amplitude of the oscillation signal, and results, for example, in no damped oscillation if the amplitude of the transformed second oscillation signal is greater than or equal to the amplitude of the oscillation signal.

[0071] Subsequently, in step S130, the possible mechanical angular position of the rotor 1a is corrected using the electrical position angle signal if it is determined in step S125b that the possible mechanical angular position of the rotor 1a does not correspond to the actual mechanical angular position of the rotor 1a.

[0072] For this purpose, the possible mechanical angular position of the rotor 1a is shifted in step S131 by one period length of the electrical position angle signal. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2023 207 191

[0032] DE 10 2023 207 178

[0032]

Claims

[1] Method for controlling an electrical machine (1) having a stator (1d) with a stator winding and a rotor (1a), the method comprising: Detecting (S100) an electrical position angle signal of the rotor (1a) and a vibration signal, Determining (S110) a possible mechanical angular position (330, 350) of the rotor (1a) using the electrical position angle signal; Determining (S120) whether the possible mechanical angular position of the rotor (1a) corresponds to an actual mechanical angular position of the rotor (1a) using the vibration signal, and Correcting (S130) the possible mechanical angular position of the rotor (1a) using the electrical position angle signal of the rotor (1a), if it is determined that the possible mechanical angular position of the rotor (1a) does not correspond to the actual mechanical angular position of the rotor (1a). [2] Method according to claim 1, wherein the electrical machine (1) further comprises a position sensor (2), in particular a resolver, which is configured to detect the electrical position angle signal of the electrical machine (1), wherein a pole pair number of the position sensor (2) is greater than one. [3] Method according to claim 2, wherein the number of pole pairs of the position sensor (2) corresponds to a number of pole pairs of the rotor (1a). [4] Method according to one of the preceding claims, wherein the electrical position angle signal is determined as a function of asymmetries of the electrical field of the electrical machine (1). [5] Method according to one of the preceding claims, wherein the vibration signal is measured by an acceleration sensor (3) which is arranged on the electrical machine (1) or on a component connected to the electrical machine (1) and is designed to measure vibrations of the electrical machine (1) or of the component connected to the electrical machine (1), wherein the acceleration sensor (3) is in particular a MEMS sensor. [6] Method according to one of the preceding claims, wherein the possible mechanical angular position of the rotor (1a) is determined (S110) as a function of a reference position in the electrical position angle signal or of a stored mechanical angular position. [7] Method according to one of the preceding claims, wherein the correcting (S130) of the possible mechanical angular position of the rotor (1a) comprises: Shifting (S131) ​​the possible mechanical angular position by one period length of the electrical position angle signal. [8] Method according to one of the preceding claims, wherein determining (S120) whether the possible mechanical angular position of the rotor (1a) corresponds to the actual mechanical angular position of the rotor (1a) comprises: Determining (S121a) a phase shift between the vibration signal (340) and the possible mechanical angular position (330, 350) of the rotor (1a), and Determining (S122a) that the possible mechanical angular position corresponds to the actual mechanical angular position of the rotor (1a) when the determined phase shift corresponds to a predetermined value, and that the possible mechanical angular position does not correspond to the actual mechanical angular position of the rotor (1a) if the determined phase shift does not correspond to the predetermined value. [9] Method according to one of the preceding claims, wherein the electric machine (1) further comprises a harmonic control which is configured to determine a damping signal for damping the vibration signal as a function of the vibration signal and the possible mechanical angular position of the rotor (1a), and determining (S120) whether the possible mechanical angular position of the rotor (1a) corresponds to the actual mechanical angular position of the rotor (1a) comprises: - Determining (S121b), by means of the harmonic control, the damping signal, - controlling (S122b) the electrical machine (1) using the damping signal, - detecting (S123b) a second vibration signal, - comparing (S124b) the vibration signal and the second vibration signal, wherein determining (S120) whether the possible mechanical angular position of the rotor (1a) corresponds to the actual mechanical angular position of the rotor (1a) comprises: - Determining (S125b) that the possible mechanical angular position of the rotor (1a) corresponds to the actual mechanical angular position of the rotor (1a) if the second oscillation signal results in an oscillation that is damped compared to the oscillation signal, or that the possible mechanical angular position of the rotor (1a) does not correspond to the actual mechanical angular position of the rotor (1a) if the second oscillation signal does not result in an oscillation that is damped compared to the oscillation signal. [10] Method according to the preceding claim, wherein comparing (S124b) the vibration signal and the second vibration signal comprises: Estimating a noise frequency using the electrical attitude angle, Performing a fast Fourier transform of the vibration signal and the second vibration signal using the noise frequency, and Comparing an amplitude of the second vibration signal and an amplitude of the vibration signal for the noise frequency. [11] Computing unit (10) which is designed to carry out all method steps of a method according to one of the preceding claims. [12] Computer program which causes a computing unit to carry out all the method steps of a method according to one of claims 1 to 10 when executed on the computing unit. [13] A machine-readable storage medium having stored thereon a computer program according to the preceding claim. [14] Drive unit (100) comprising an electrical machine (1) with a stator with a stator winding and a rotor (1a), an acceleration sensor (3) which is designed to measure vibrations of the electrical machine (1) or of a component (5) connected to the electrical machine (1), an inverter (6) which is designed to supply the stator (1d) of the electrical machine (1) with current, and a computing unit (10) according to claim 11. [15] Drive unit (100) according to claim 14, further comprising a position sensor (2) which is configured to detect an electrical position angle of the rotor (1a) of the electrical machine (1).

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