DE102021132391A1 - Method for operating a drive train of a motor vehicle, control device for carrying out a method for operating a drive train of a motor vehicle, drive arrangement comprising a drive train of a motor vehicle, motor vehicle - Google Patents

Abstract

Method for operating a drive train (2) of a motor vehicle (1), comprising an electric machine (5) for generating a drive torque (MEM) which is transmitted via at least one transmission component (7) of the drive train (2) to at least one wheel (6) of the Motor vehicle (1) is transmitted, wherein a control device (12) generates a control signal (25) by means of which the electric machine (5) is controlled and which describes the drive torque (MEM) currently to be generated by the electric machine (5), wherein Machine rotation information (19) relating to a current angle of rotation (αRotor) and/or a current rotational speed of a rotor (4) of the electrical machine (5) is recorded by means of a machine rotation detection means (13), the control signal (25) depending on the machine rotation information (19 ) and/or an input variable determined by means of the machine rotation information (19).

Description

The present invention relates to a method for operating a drive train of a motor vehicle, comprising an electric machine for generating a drive torque which is transmitted to at least one wheel of the motor vehicle via at least one transmission component of the drive train, with a control device generating a control signal by means of which the electric machine is controlled and which describes the drive torque currently to be generated by the electric machine. The drive torque is abbreviated as M _EM in the following.

Typically, in connection with the generation of the control signal for controlling the electric machine, a control algorithm is used, with a desired drive torque to be generated by means of the electric machine and specified by the driver, which is referred to below as M _set , and optionally used as the control basis or control input variable wheel rotation information relating to a current rotational position of a wheel of the motor vehicle is used. The disadvantage here is that the control input variables can only be detected with a relatively high level of inaccuracy, which in turn has a disadvantageous effect, for example with regard to the most uniform possible acceleration behavior of the motor vehicle.

The object of the present invention is to specify an improved concept for operating a drive train of a motor vehicle.

According to the invention, the object is achieved in that, in a method of the type mentioned at the outset, machine rotation information relating to a current angle of rotation and/or a current rotational speed of a rotor of the electrical machine is recorded by means of a machine rotation detection means, with the control signal depending on the machine rotation information and/or a means the machine rotation information determined input variable is generated. The current angle of rotation of the rotor is referred to below as α _rotor .

The invention is based on the idea that the machine rotation information not only represents an alternative or additional source of information that can be used in connection with the generation of the control signal, but that measured variables relating to the current rotational movement of the rotor are compared to those in the prior art for this purpose In principle, the measured variables recorded can be determined with a higher degree of accuracy, which is why details in this regard will be explained later. Consequently, an optimized control of the electric machine is made possible such that the drive torque M _EM to be generated can be better adapted to the current circumstances in the drive train, which can reduce or even avoid acceleration fluctuations that have a disadvantageous effect on driving comfort.

Although a sensor provided specifically for this purpose is conceivable as the machine rotation detection means, a component that is already present is preferably used for this purpose, for example a rotary encoder of the electrical machine that is provided anyway. No additional components are absolutely necessary to implement the present invention.

The drive train of the motor vehicle includes all of the components that are provided for generating and transmitting the drive power or the drive torque from the power source to the wheels of the motor vehicle. In concrete terms, the drive torque M _EM is generated by means of the electrical machine, with the electrical machine being coupled to the wheels via the transmission components in order to transmit this power. The drive train therefore includes the electric machine, the transmission components and the wheels.

Rotary or torsion shafts and clutches are often provided as transmission components, by means of which the drive torque transmission can be decoupled.

Furthermore, the transmission components are often gears, in particular switchable gears, by means of which different speeds can be translated according to a gear ratio, so that the wheels do not necessarily have the same rotational frequency as the rotor. The transmission ratio relating to the transmission is referred to below as i _G . Furthermore, an axle differential or differential gear can be provided in the area of a drive axle of the motor vehicle, by means of which the drive power can be distributed differently to the wheels of this axle. In addition, other transmission components are conceivable, with the basic functioning of a drive train being well known to a person skilled in the art and therefore not being explained further at this point.

The control device can also be referred to as a control device or ECU (“electronic control unit”) and is an electronic module by means of which the control and regulation process can be carried out. It may include an electronic data storage medium on which data relevant for carrying out the method according to the invention are stored. Thus, for example when a predetermined time interval has elapsed, the machine rotation information can be recorded and a corresponding value can be stored, so that a data record relating to the progression of these values over time is generated. The control device can be connected to the components involved in the method via a bus system of the motor vehicle. The control device can be provided specifically for carrying out the method according to the invention or additionally set up for further control or regulation purposes in the motor vehicle.

The current angle of rotation α _rotor is in particular a current, absolute angle of rotation of the rotor, which indicates the current rotational position of the rotor with respect to a reference rotational position. In other words, the angle of rotation α _rotor is the angle of rotation of a reference point fixedly arranged on the rotor in relation to a defined rotational position of the rotor, approximately a 12 o'clock position. In practice, in connection with the determination of the angle of rotation α _rotor , instead of detecting a specific numerical value between 0 and 360°, it can be provided that the rotational movement is detected by means of an incremental encoder. This means that after a rotation increment has been run through, a counter is incremented by a value of 1. If the electrical machine has multiple poles, then a sensor, by means of which the change in the magnetic field is detected, supplies a signal covering the range from 0° to 360° each time a pole is passed through. For example, such a sensor of a four-pole electric motor will run through the angle range from 0° to 360° four times during a complete rotation of the rotor by 360°. In order to record the current rotational position of the rotor, it is therefore necessary not only to record the current value of the angle in relation to the respective magnetic pole, but also to record a so-called overflow, i.e. an integer value, how often the range from 0° up to 360° has already been run through.

In the method according to the invention, provision can be made for wheel rotation information relating to a current angle of rotation and/or a current speed of rotation of the wheel to be recorded by means of a wheel rotation detection means, with the machine rotation information and the wheel rotation information being used to determine a current relative angle of rotation of the rotor, which indicates the current rotational position of the Rotor is relative to the current rotational position of the wheel, the control signal being generated as a function of the relative angle of rotation and/or an input variable determined by means of the relative angle of rotation. The current angle of rotation of the wheel is referred to below as α _wheel and the current relative angle of rotation of the rotor as α* _rotor . A specific angle between 0° and 360° does not necessarily have to be detected to determine the rotation angle α _wheel using the wheel rotation detection means, but the angle can be determined indirectly using an incremental detection as already explained in connection with the detection of α _rotor .

The current angle of rotation α _wheel is in particular a current, absolute angle of rotation of the wheel, which indicates the current rotational position of the wheel with respect to a reference rotational position. In other words, the angle of rotation α _wheel is the angle of rotation of a fixed reference point on the wheel in relation to a defined rotational position, for example a 12 o'clock position. The current relative rotation angle α* _rotor is the angle difference between these two reference points and thus results in α* _rotor = α _rotor - α _wheel or vice versa. In particular, if the drive train comprises a differential gear, provision can be made for a plurality of wheel rotation detection means assigned to different wheels to be provided for this purpose, since in this case the rotational positions of the wheels can differ. This circumstance can be taken into account when carrying out the method according to the invention.

In the case of incremental detection of the rotational movement, which is often relevant in practice, the relative angle of rotation α* of _{the rotor} can also be detected by a counter increasing by 1 when a rotational increment is run through for the rotor and by 1 when a rotational increment is run through for the wheel is lowered. The correspondingly obtained counter value directly describes the relative rotation angle α* _rotor between the rotor and the wheel. In the case of a multi-pole electrical machine, the fact explained above must be taken into account here that the sensor senses several runs of the interval from 0° to 360° during a complete rotation of the rotor.

The wheel rotation detection means is a rotation sensor, for example, which can be provided in any case in connection with an ABS system of the motor vehicle. In ABS systems, the angle is typically detected using the incremental detection method already explained above.

An advantage in connection with the detection of the relative rotation angle α* _rotor of the rotor is that this is determined by other state variables of the drive train in comparison to the fact that only the absolute only α _rotor is detected, attached, which can be included in the generation of the control signal. Specific aspects in this regard will be discussed in detail later.

In the method according to the invention, it is preferably provided that the control device is used to determine, in particular calculate, an ideal rotation angle of the rotor when the drive train is in a fault-free, in particular torsional vibration-free state, with the control device determining an angular deviation between a current rotation angle of the rotor and the ideal rotation angle of the Rotor is determined, the control signal being generated as a function of the angular deviation and/or an input variable determined by means of the angular deviation. The ideal rotation angle of the rotor is referred to below as α _set , the current rotation angle of the rotor _as α and the angular deviation as Δα.

A fault-free ideal case is thus assumed or simulated by means of the control device and the ideal rotation angle α _desired to be expected is determined from this. This determination can be made using a lookup table stored by the control device or an analytical calculation based, for example, on a model of the drive train. The angular deviation results in Δα=α _set −α _actual or vice versa. The control or regulation can take place in such a way that the value of Δα becomes as small as possible, that is to say that the real state is adjusted as closely as possible to the fault-free ideal case.

At least one piece of information can be recorded and taken into account in order to determine the ideal rotation angle α _desired and/or as part of a regulation specification that is used to generate the control signal. In this way, elasticity information can be taken into account, which describes an elastic behavior of the transmission components when the drive torque is transmitted. In general, the elasticity information relates to what is known as an elasticity function, which describes the elastic behavior of the drive train or its components as a function of one variable or multiple variables. In particular, the elasticity information can relate to an elasticity constant of the transmission components when the drive torque is transmitted, which depends in particular on the value of the drive torque. The elasticity constant is denoted by E _AS in the following. This takes into account the fact that the transmission components have elasticity or rigidity, so that the drive train can be understood as a model and idealized as a system in which the rotor and the wheel are connected to one another by means of an elastic torsion spring. If the electrical machine generates a drive torque M _EM , then due to the elasticity of these components, a stress-caused angular deviation, referred to below as Δα _M , is caused in the transmission components. According to Hooke's law, this is all the greater, the greater the drive torque M _EM . In particular, a linear relationship between M _EM and Δα _M can be assumed. The elasticity constant E _AS can thus be understood as the spring constant of the overall system of transmission components that couple the rotor to the wheel. It can also be taken into account here that the elasticity constant E _AS depends on the value of the drive torque M _EM currently present, which is caused, for example, by vibration dampers in the drive train. The stress-caused angular deviation Δα _M thus represents a measure of the drive torque M _EM currently being transmitted by means of the drive train.

Additionally or alternatively, transmission information can be taken into account, which relates to a transmission ratio between the rotor and the wheel brought about by means of the drive train, in particular by means of a transmission of the drive train. The transmission ratio of the drive train is referred to below as i _AS . If there were a transmission ratio of i _AS = 1 in the drive train, the machine rotation information and the wheel rotation information would result in the relative rotation angle α* _rotor being constant over time if there were no torsional vibrations or faults, since the relative rotation position between the rotor and the wheel does not change in this case. If the transmission ratio i _AS ≠ 1, the relative rotation angle α* _rotor would not be constant over time, but would increase or decrease according to a linear relationship. The gradient of the corresponding straight line depends on the gear ratio i _AS . The transmission ratio i _AS is defined in particular as the quotient of the revolution period of the wheel and the revolution period of the rotor or vice versa.

Furthermore, play information can be taken into account, which describes play present in the drive train when the drive torque is being transmitted. Here, a play in the drive train that is present due to the transmission components is taken into account. The value of the play, which is referred to below as S _AS , can indicate the maximum angle of rotation of the rotor by which it can be rotated without causing the wheel to rotate and at the same time the drive train remains stress-free.

Additionally or alternatively, a drive torque information can be taken into account that a driving torque specified by the driver is concerned. This is particularly expedient if the angular deviation Δα _M caused by the stress is to be taken into account for the determination of α _setpoint , since this, as already mentioned, depends on the drive torque. As already mentioned above, the drive torque specified by the driver is abbreviated as M _set .

A problem that is known in connection with an electric machine as a drive source for a motor vehicle relates to torsional vibrations occurring in the drive train. These are vibrations present in the area of the drive train, which are superimposed on the rotational movement present on the part of the transmission components. The electric machine is often the source of the torsional vibrations in the drive train, since, for example, asymmetries in the electromagnetic field in the electric machine can lead to fluctuations in the drive torque, which are also referred to as "torque ripple". Another frequent cause of torsional vibrations are abrupt changes in the position of an accelerator pedal and thus rapid changes in the drive torque transmitted via the drive train. Since the transmission components of the drive train have an elasticity or rigidity with regard to their torsional stress, the torsional vibrations are propagated in the entire drive train, which has a negative effect on the driving behavior of the motor vehicle that can be perceived by the driver. This effect is particularly pronounced when the electric machine generates a drive torque with a frequency that coincides with a resonant frequency of the drive train. Typical effects are uneven acceleration processes or jerking.

With regard to this problem, it can be provided in the method according to the invention that, on the basis of the machine rotation information and/or the input variable determined using the machine rotation information and by means of the control device, it is determined whether there is currently torsional vibration in the drive train and/or the occurrence of torsional vibration, in particular with a known vibration period, is imminent, in which case a parameter of the torsional vibration is determined on the basis of the machine rotation information and/or the input variable determined using the machine rotation information, wherein the control device uses the parameter to generate the control signal in such a way that a variation over time of the drive torque the torsional vibration at least partially compensated. In this context, the term "compensate" means that the vibrating system, i.e. the drive train, is deprived of energy that is present or stored in this system due to the torsional vibration. In other words, in this embodiment, the torsional vibration is damped. A variable torque can thus be superimposed on the drive torque M _EM in such a way that vibrational energy is extracted with respect to the vibrational movement of the vibrating system.

This evaluation is particularly preferably based on the angular deviation and/or the input variable determined using the angular deviation, the angular deviation being the deviation between the current rotational position of the rotor and a rotational position of the rotor when the drive train is in a torsional vibration-free state. The recorded machine rotation information or the angle deviation Δα allows the presence of a torsional vibration and its parameters to be determined virtually without a time delay. Based on this, the drive torque M _EM is adjusted or varied by means of the control signal in such a way that a further torsional vibration is specifically fed into the drive train, so that active damping of the present torsional vibration is effected in order to weaken the torsional vibration or, ideally, to completely eliminate it.

If it is determined whether a torsional vibration is imminent, for example with a known period of vibration, the variation of the drive torque M _EM can be used to dampen this torsional vibration right from the start, i.e. when the vibration amplitude is still very weak or is weakened. In this case, it can be used in particular that torsional vibrations typically occur at so-called resonant frequencies, which can be known based on corresponding measurements or modelling. These known oscillation periods can be used in such a way that the variation over time of the drive torque M _EM is already initiated when it is evident that such a torsional oscillation is about to occur or the course over time of α _rotor , α actual _and /or Δα implies that the resonant frequency of the torsional vibration is reached.

• - eine aktuelle oder zu erwartende Amplitude und/oder
• - eine aktuelle oder zu erwartende Phase und/oder
• - eine aktuelle oder zu erwartende Schwingungsperiode

der Drehschwingung ist, wobei die elektrische Maschine mittels des Steuersignals derart angesteuert wird, dass dem Antriebsmoment ein sich, insbesondere periodisch, änderndes und von der Amplitude und/oder der Phase und/oder der Schwingungsperiode abhängendes Drehmoment derart aufgeprägt wird, dass die Drehschwingung gedämpft wird. So kann mittels der elektrischen Maschine zusätzlich zu dem Antriebsmoment ein Drehmoment erzeugt werden, das das Antriebsmoment überlagert. Die Amplitude wird nachfolgend mit A, die Phase mit φ und die Schwingungsperiode mit P abgekürzt.In connection with the at least partial compensation of the torsional vibration, it can be provided that the parameter

• - a current or expected amplitude and/or
• - a current or anticipated phase and/or
• - a current or expected period of oscillation

of the torsional vibration, the electrical machine being controlled by means of the control signal in such a way that a torque that changes, in particular periodically, and depends on the amplitude and/or the phase and/or the period of oscillation is impressed on the drive torque in such a way that the torsional vibration is damped . In addition to the drive torque, the electric machine can thus generate a torque that is superimposed on the drive torque. The amplitude is hereinafter abbreviated as A, the phase as φ and the period of oscillation as P.

In particular, a torsional vibration that is phase-shifted by approximately, in particular exactly, 180° and has the same or similar vibration period and in particular the same or similar amplitude can be applied to the drive torque.

If all three variables A, φ and P of the torsional vibration that has or is occurring are known, the torsional vibration that has been generated can be weakened or, ideally, completely eliminated by generating the anti-rotational vibration, which is phase-shifted by 180° in particular, if the amplitude and the oscillation period of the anti-rotational vibration Correspond to values of the resulting or emerging torsional vibration. A weakening or damping of the torsional vibration can, however, also take place by means of vibrations which have a phase shift deviating from 180°. The additional torque can have a signal shape that differs from the existing torsional vibration. Thus, not only a sinusoidal shape, but also a triangular or rectangular shape can be provided for the anti-rotational vibration. Due to the continuous acquisition and evaluation of the corresponding information, any changes in the parameters of the torsional vibration can be detected with virtually no time delay and taken into account when generating the anti-torsional vibration.

As part of the method according to the invention, it can be provided that, in order to generate the control signal, the control device uses a PID control algorithm or PD control algorithm with a constant or variable P factor relating to the P element and a constant one, in particular dependent on the speed of the motor vehicle or variable, in particular dependent on the speed of the motor vehicle, D-factor relating to the D-element is used. In the following, the P factor is abbreviated as k _P , the D factor as k _D and the speed of the motor vehicle as v.

berechnet, wobei der erste Summand das P-Glied, der zweite Summand ein I-Glied, der dritte Summand das D-Glied und k_I einen I-Faktor betreffend ein I-Glied darstellt. Im Falle eines PD-Regelalgrithmus ist k_I = 0.In the PID control algorithm, an output variable a(t) dependent on a time t is converted from a time-dependent control input variable e(t) by means $$a\left(t\right)=k_P\cdot e\left(t\right)+k_l\cdot {\displaystyle {\int }_0^{t}e\left(\tau \right)\mathrm{i.e}\tau +k_D\cdot \frac{\mathrm{i.e}}{\mathrm{i.e}t}e\left(t\right)}$$

calculated, with the first summand representing the P element, the second summand an I element, the third summand the D element and k _I an I factor relating to an I element. In the case of a PD control algorithm, k _I = 0.

The angular deviation Δα can be used as a control input variable. The regulation is preferably carried out in such a way that the drive torque M _EM of the electrical machine is changed in such a way that the angular deviation Δα is as small as possible or ideally zero.

With regard to the factors k _P and k _D it can be provided that these are constant. It is also conceivable that variable values are used as a basis. Provision can be made, for example, for k _P and k _D to depend on the current speed v of the motor vehicle and, in particular, to be smaller the greater the speed v. With regard to torsional vibration damping, this means that this is less and less taken into account in the control with increasing speed, which is expedient given that torsional vibrations usually no longer occur at high speeds of the motor vehicle, or at least to a lesser extent. The compensation of the torsional vibrations is thus advantageously increased at very low speeds v.

Furthermore, the object on which the invention is based is achieved according to the invention by a control device which is set up to carry out the method according to the above description. All the advantages, features and aspects explained in connection with the method according to the invention apply equally to the control device according to the invention and vice versa.

The invention further relates to a drive arrangement comprising a drive train of a motor vehicle with an electric machine for generating a drive torque which can be transmitted to at least one wheel of the motor vehicle via at least one transmission component of the drive train, wherein a control device of the drive arrangement is set up to generate a control signal, by means of which the electrical machine can be controlled and which is currently being generated by the electrical machine low drive torque describes. According to the invention, the object is achieved with such a drive arrangement in that machine rotation information relating to a current angle of rotation and/or a current rotational speed of a rotor can be detected by means of a machine rotation detection means of the drive arrangement, the control signal depending on the machine rotation information and/or an input variable determined using the machine rotation information is producible. All the features, advantages and aspects described in connection with the method according to the invention and the control device according to the invention can be transferred equally to the drive arrangement according to the invention and vice versa.

The object on which the invention is based is also achieved according to the invention by a motor vehicle comprising a drive arrangement according to the preceding description. All advantages, features and aspects explained in connection with the method according to the invention, the control device according to the invention and the drive arrangement according to the invention are equally applicable to the motor vehicle according to the invention and vice versa.

• 1 ein Ausführungsbeispiel eines erfindungsgemäßen Kraftfahrzeugs mit einem Ausführungsbeispiel einer erfindungsgemäßen Antriebsanordnung,
• 2 ein Flussdiagramm eines ersten Ausführungsbeispiels des erfindungsgemäßen Verfahrens, das anhand des Kraftfahrzeugs der 1 erläutert wird,
• 3 ein Diagramm betreffend den zeitlichen Verlauf des relativen Rotationswinkels α*_Rotor beim Kraftfahrzeug aus 1 und Verfahren aus 2, wobei ein Übersetzungsverhältnis von i_AS = 1 vorliegt,
• 4 ein Diagramm betreffend den zeitlichen Verlauf des relativen Rotationswinkels α*_Rotor beim Kraftfahrzeug aus 1 und Verfahren aus 2, wobei ein Übersetzungsverhältnis von i_AS ≠ 1 vorliegt,
• 5 ein Diagramm betreffend den zeitlichen Verlauf der Drehzahl des Rotors der elektrischen Maschine des Kraftfahrzeugs aus 1,
• 6 ein Diagramm betreffend den zeitlichen Verlauf der Beschleunigung des Kraftfahrzeugs aus 1,
• 7 ein Flussdiagramm eines zweiten Ausführungsbeispiels des erfindungsgemäßen Verfahrens, das anhand des Kraftfahrzeugs der 1 erläutert wird,
• 8 eine modellhafte Darstellung des Antriebsstrangs des Kraftfahrzeugs der 1, und
• 9 ein Diagramm betreffend den zeitlichen Verlauf des relativen Rotationswinkels α*_Rotor beim Kraftfahrzeug aus 1 und Verfahren aus 7.

The invention is explained below using exemplary embodiments with reference to the figures. These show schematically:

• 1 an embodiment of a motor vehicle according to the invention with an embodiment of a drive assembly according to the invention,
• 2 a flowchart of a first embodiment of the method according to the invention, which is based on the motor vehicle 1 is explained
• 3 a diagram relating to the time course of the relative rotation angle α* _{of the rotor} in a motor vehicle 1 and procedures 2 , with a transmission ratio of i _AS = 1,
• 4 a diagram relating to the time course of the relative rotation angle α* _{of the rotor} in a motor vehicle 1 and procedures 2 , with a transmission ratio of i _AS ≠ 1,
• 5 a diagram relating to the time course of the speed of the rotor of the electric machine of the motor vehicle 1 ,
• 6 a diagram relating to the time course of the acceleration of the motor vehicle 1 ,
• 7 a flowchart of a second embodiment of the method according to the invention, which is based on the motor vehicle 1 is explained
• 8th a model representation of the drive train of the motor vehicle 1 , and
• 9 a diagram relating to the time course of the relative rotation angle α* _{of the rotor} in a motor vehicle 1 and procedures 7 .

1 1 shows a motor vehicle 1 according to the invention with a drive train 2. The drive train 2 comprises an electric machine 5 having a stator 3 and a rotor 4, by means of which a drive torque M _EM can be generated, which is transmitted to wheels 6 of the motor vehicle 1. Transmission components 7 of the drive train 2 are provided for the transmission of the drive torque M _EM . These are, for example, a first drive shaft 8 which is connected on the one hand to the rotor 4 and on the other hand to a transmission 9 of the drive train 2 . The drive train 2 also includes a second drive shaft 10 connected on the one hand to the transmission 9 and on the other hand to a drive axle 11 of the motor vehicle 1. The second drive shaft 10 can be coupled to the drive axle 11 via a differential gear, not shown in detail. The drive axle 11 is connected to the wheels 6 of the motor vehicle 1 . It can be seen in the in 1 Motor vehicle 1 shown is provided with a front axle drive, with a rear axle drive or all-wheel drive being equally conceivable.

The motor vehicle 1 includes a control device 12 which is connected to the electric machine 5, among other things. For reasons of clarity, the connecting lines in the 1 not shown. The control device 12 is set up to generate a control signal 25 by means of which the electric machine 5 is controlled, the control signal 25 describing the drive torque M _EM currently to be generated by the electric machine 5 .

The motor vehicle 1 includes a machine rotation detection means 13, namely a rotary encoder of the electric machine 5, by means of which a rotary movement of the rotor 4 is detected. Specifically, a current rotational position of the rotor 4, ie a rotational angle α _rotor , is detected by means of the machine rotation detection means 13, which in turn is transmitted to the control device 12 for further evaluation.

In the present invention it is provided that by means of the machine rotation detection The angle of rotation α _rotor of the rotor 4 detected by means of 13 represents a control or regulation basis for generating the control signal 25, or that a control input variable is calculated or determined based on the angle of rotation α _rotor , which forms a control or regulation basis for generating the control signal 25 represents. The control or regulation of the electrical machine 5 is thus based on α _rotor or a regulation variable derived therefrom, further variables or information being used as an example in the exemplary embodiments explained, which will be discussed in detail below.

The arrangement comprising the drive train 2 and the control device 12 represents a drive arrangement 14 according to the invention of the motor vehicle 1.

2 shows a flowchart of a first embodiment of the method according to the invention based on the motor vehicle 1 of FIG 1 . The aspects explained in connection with this exemplary embodiment relate primarily to the compensation of any torsional vibrations present in the drive train 2 , which arise in particular due to so-called “torque ripple”, ie vibrations of the drive torque provided by the electric machine 5 . The method comprises steps 15 to 18, which the control device 12 in particular is set up to carry out.

In the first step 15 , machine rotation information 19 and wheel rotation information 20 are recorded and transmitted to the control device 12 . The machine rotation information 19 is acquired by means of the machine rotation acquisition means 13, this information being or describing the current rotational position or the current rotational _angle α of the rotor 4 . A wheel rotation detection means 21 is provided for detecting the wheel rotation information 20, which is an example of a sensor already provided as part of an ABS system of the motor vehicle 1, by means of which the current rotational position or a current rotational angle α _wheel of the wheel 6 is detected. Although only one wheel rotation detection means 21 is provided on one of the wheels 6 in the exemplary embodiment shown, it is equally conceivable, particularly if the drive train 2 comprises a differential gear, for a plurality of wheel rotation detection means 21 assigned to different wheels 6 to be provided for this purpose, since in this case the Rotational positions of the wheels 6 can differ, which can be taken into account when carrying out the present method.

In the second step 16 of the method, a current relative angle of rotation α* _rotor of the rotor 4 is determined or calculated using the machine rotation information 19 and the wheel rotation information 20. The relative angle α* _rotor is the angle difference between the current absolute rotation angle α _rotor of the rotor 4 and the current absolute rotation angle α _wheel of wheel 6. The value for α* _rotor is calculated according to α _rotor - α _wheel or vice versa. The relative angle α* _rotor represents an actual relative rotation angle _α actual between the rotor 4 and the wheel 6. As part of the second step 16, an ideal absolute or relative rotation angle α _desired of the rotor 4 is also calculated, which occurs in a malfunction - Or torsional vibration-free state of the drive train 2 would be present.

For a better understanding, these sizes are shown below using the 3 and 4 explained. 3 shows a diagram whose x-axis relates to time and whose y-axis relates to the relative angle α* _rotor . With reference to 3 let it be assumed that the drive train 2 has a transmission ratio i _AS =1, ie that the rotational frequency of the rotor 4 corresponds to the rotational frequency of the wheel 6 . In this case, the ideal rotation angle α _desired of the rotor 4 is a constant value, which becomes clear from the graph 22, which is a horizontal straight line with a slope=0. However, this only applies to the ideal case in which there is currently no fault, in particular torsional vibration, in the drive train 2 . The real progression of the relative angle α _is in 3 shown by graph 23. Due to the torsional vibration, the course of graph 23 oscillates around graph 22.

This in 4 diagram shown shows the same as 3 , but with the difference that the drive train 2 has a transmission ratio i _AS ≠ 1, where i _AS is a transmission ratio i _G of the transmission 9 . So is in 4 Graph 22 is a straight line with a gradient ≠0, with the torsional vibration leading to a real profile of the relative rotation angle α _act according to graph 23 .

As part of the second step 16, an angular discrepancy Δα between the current angle of rotation _αactual and the ideal angle of rotation _{αnom is} calculated according to Δα= _αnom −αact. The angular deviation Δα is in the 3 and 4 indicated by the arrow 24. In a fault-free or torsional vibration-free state of the drive train 2, there would be an angular deviation Δα of constant 0.

In the next step 17 of the method, the angle deviation Δα is evaluated to determine whether there is torsional vibration in the drive train. Unless this is the case, that is if Δα is constantly 0 or smaller than a predetermined limit value, the method is restarted in step 15. If it turns out that a torsional vibration is present, then parameters relating to the torsional vibration are determined. Specifically, an amplitude A, a phase φ and an oscillation period P of the torsional oscillation are determined on the basis of the angular deviation Δα.

Then, in the last step 18, the control signal 25 is generated. This takes place as a function of the parameters A, φ and P determined in step 17. The drive torque M _EM generated by the electric machine 5 by means of the control signal 25 varies over time in such a way that the torsional vibration present is compensated or damped. In other words, vibration energy is withdrawn from the system comprising the vibrating components. In concrete terms, an oscillation is imposed on the drive torque M _EM which has the same oscillation period P and the same amplitude A as the torsional oscillation, the counter-torsional oscillation which is imposed being phase-shifted by 180°. Damping or compensating for the torsional vibration is brought about by this measure. With regard to the anti-rotational vibration, it can likewise be provided that this has a phase shift deviating from 180°. The waveform of the anti-rotational vibration can be sinusoidal, triangular or square-wave.

Some advantages brought about by the present invention are described below with reference to FIG 5 and 6 explained. 5 shows a diagram relating to a starting process of the motor vehicle 1, the x-axis representing the time and the y-axis representing a current speed of the rotor 4. At the in 5 Graphs 26 shown are not compensated for the torsional vibration according to the above description. It becomes clear that as soon as the rotor 4 begins to rotate, the speed fluctuates due to the torsional vibrations that occur, especially in the low speed range. 6 shows an effect of these torsional vibrations caused by this and particularly noticeable by the driver. Thus, the x-axis relates to time and the y-axis to an acceleration of the motor vehicle 1, which is due to the variation in the speed of the rotor 4 in accordance with 5 , especially in the low speed range, varies significantly. This is how the in 6 Graph 27 shown causes the effect that starting from the driver's point of view is not smooth and smooth, but rather jerky and uneven, which is disadvantageous in terms of driving comfort. By compensating for the torsional vibrations based on the 2 the methods explained in the 5 and 6 Graphs 26, 27 shown are clearly smoothed, so that motor vehicle 1 starts or accelerates smoothly and evenly.

A frequently relevant aspect in connection with the detection of the rotation angles, ie the already explained angles α _rotor , α _wheel , α* _rotor , α _target , α _actual and Δα as well as other quantities relating to the rotation angles explained later, is explained below. In the exemplary embodiments explained here, it is assumed that an angle is detected in that it is described using a numerical value from 0° to 360°. However, this is only to be understood as an example. It is conceivable that the angle is detected as part of an incremental encoder, both on the part of the electric machine 5 and on the part of the wheels 6. This means that after a rotation increment has been run through in the electric machine 5, a counter increases by a value of 1 up and down after going through one rotational increment at wheel 6 and 1. As a result, a value describing the relative rotation angle α* _rotor between the rotor 4 and the wheel 6 is determined directly. If the electrical machine 5 has multiple poles, it must be taken into account here that a sensor, by means of which the change in the magnetic field is detected, supplies a signal covering the range from 0° to 360° each time it passes through a pole.

Below is a possible variation, also within the scope of the present invention, based on the 2 explained procedure. With this modification, it is not absolutely necessary for the wheel rotation information 20 to be recorded and evaluated, so that the second step 16 relating to the determination of the relative angle α* _rotor of the rotor 4 can be omitted. Step 17 differs from that based on FIG 2 explained method to the effect that the knowledge of an oscillation period P or resonant frequency of a typically occurring torsional vibration is required. If the values for α _rotor imply that a resonant frequency is reached, even if the torsional vibration is currently only very weakly pronounced, temporal variations in the drive torque M _EM can be generated in step 18, so that the torsional vibration is already present from the start is dampened or compensated for and ultimately does not occur noticeably from the driver's point of view.

Another embodiment of the method is based on the 7 explained. This method comprises steps 28 to 30, with the first step 28 corresponding to step 15 of the method 2 corresponds, namely relating to the detection of the machine rotation information 19 and the wheel rotation information 20, ie the Angular position α _rotor of the rotor and angular position α _wheel of the wheel.

In the second step 29 of the method, just like in the second step 16 of the method 2 , the current relative angle of rotation α* _rotor of the rotor 4, ie the angle α _is , the angle α _{is intended} and the angular deviation Δα is determined. A stress-caused angular discrepancy Δα _M between the actual rotational position of the rotor 4 and a rotational position of the rotor 4 in a stress-free state of the drive train 2 _is taken into account as a difference when determining α set .

For a better understanding of the stress-caused angle deviation Δα _M is on the 8th and 9 referenced. 8th shows a model of the drive train 2, the rotor 4 and the wheel 6 being coupled to one another via the transmission components 7. The rotation of the transmission components 7 is indicated by the arrow 31 . The transmission components 7 are in 8th symbolically indicated as an elastic torsion spring. Thus, the transmission components 7 have an elasticity or rigidity with regard to the transmission of the drive torque M _EM . If no drive torque M _EM is transmitted, then the transmission components 7 are in a stress-free state, so that no elastic deformation occurs. If a drive torque M _EM is transmitted via the drive train 2, this causes an elastic deformation with regard to the angle of rotation of the transmission components 7. According to Hooke's law, an additional rotation of the rotational position of the rotor 4 caused by the elasticity of the transmission components 7 by an angular deviation caused by stress Δα _M the sequence. It can be seen that the voltage-caused angular deviation Δα _M is a measure of the drive torque M _EM generated by means of the rotor 4 or the electric machine 5 .

9 shows a diagram whose x-axis relates to time and whose y-axis relates to the current angle α* of the _rotor 4 . An acceleration phase of the motor vehicle 1 is shown, with a first drive torque M _EM1 being generated in a first time segment 32 and a second drive torque M _EM2 being generated in a second time segment 33 by means of the electrical machine 5, with M _EM1 being greater than M _EM2 . During the transition from the first time segment 32 to the second time segment 33, the transmission 9 is used to shift from a first to a second gear, so that the gradients change due to the different values of the transmission ratio i _AS . Graph 34 shows the course if the drive train 2 were stress-free or if it had no elasticity but rather rigid behavior. The graph 35 shows the course corrected with regard to the elasticity of the transmission components 7 . It is clear that in the first period of time 32 in comparison to the second period of time 33, because M _EM1 is greater than M _EM2 , a stronger elastic deformation occurs in the drive train 2 . In concrete terms, an accelerator pedal 36 of motor vehicle 1 is pressed harder in first time segment 32 than in second time segment 33. Angle deviation Δα _M caused by stress is in FIG 9 indicated by the arrow 37.

Details regarding the specific regulation are explained below, which in the context of the second step 29 of the method 7 is applied, where Δα is the control input variable. In order to determine Δα, elasticity information 38, play information 39 and drive torque information 40 are first determined. The information 38 and 39 can be ascertained by the control device 12 storing and specifying it.

In the present exemplary embodiment, the elasticity information 38 only relates to the elasticity constant E _AS of the drive train 2, which is present when the drive torque M _EM is transmitted, with E _AS being able to be constant or dependent on the value of the drive torque M _EM . In general, the elasticity information 38 can relate to a so-called elasticity function, which allows the elastic behavior of the drive train 2 or its components to be described as a function of the drive torque M _EM and possibly other state variables of the oscillating system or drive train 2 .

The play information 39 relates to a play S _AS present in the drive train 2 during the transmission of the drive torque M _EM . The variable S _AS describes the angle of rotation of the rotor 4 by which it can be rotated as a maximum without causing the wheel 6 to rotate, with no elastic deformation occurring in the drive train 2 .

The drive torque information 40 relates to the drive torque M _desired specified by the driver and is specified by means of the gas pedal 36 of the motor vehicle 1 . The default drive torque M _setpoint is available within the framework of a vehicle controller 41 and is transmitted to the controller 12 . Furthermore, as part of step 29, the transmission information 42 is determined, which describes the transmission ratio i _AS between the rotor 4 and the wheel 6 brought about by means of the drive train 2, in particular by means of the transmission 9. This information is also available within the framework of vehicle control 41 .

berechnet. Diese Größe entspricht dem Graphen 35 in 9 und ist bereits bezüglich Δα_M bereinigt. Der aktuelle Rotationswinkel α_ist entspricht dem ermittelten relativen tatsächlichen Rotationswinkel α*_Rotor des Rotors 4, der in 9 durch den Graphen 43 angedeutet wird und, etwa aufgrund einer Drehschwingung, von dem idealen Graphen 35 abweicht. Die Regelungs-Eingangsgröße Δα, die in 9 durch den Pfeil 44 angedeutet ist, ergibt sich zu $$\mathrm{\Delta }\alpha ={\alpha }_{soll}-{\alpha }_{ist}.$$

Specifically, based on the wheel rotation information 20, the ideal rotation angle α _set of the rotor 4 according to $$a_{sOll}=\frac{M_{sOll}}{E_{AS}}+S_{AS}+a_{Ra\mathrm{i.e}}\cdot i_{AS}$$

calculated. This size corresponds to the graph 35 in 9 and has already been corrected for Δα _M . The current angle of rotation α _ist corresponds to the determined relative actual angle of rotation α* _rotor of the rotor 4, which is 9 is indicated by the graph 43 and deviates from the ideal graph 35, for example due to a torsional vibration. The control input variable Δα, which is 9 is indicated by the arrow 44 results in $$\mathrm{\Delta }a=a_{sOll}-a_{ist}.$$

The drive torque M _EM to be generated by the electric machine 5 is determined by means of a PD control algorithm, so that Δα is approximately 0 or approaches another target value. The relevant regulation is: $$M_{EM}=\mathrm{\Delta }a\cdot k_P+{\mathrm{\Delta }}^{\cdot }a\cdot k_D+M_{sOll}\cdot k_M.$$

Here, k _P is the P factor and k _D is the D factor relating to the P or D element of the PD control algorithm. The factor k _M is a proportionality factor for the proportion of a target drive torque M _set which is included in the regulation, with k _M taking into account the difference between the drive torque generated on the engine side and the drive torque applied to the wheels 6 caused by the transmission components 7 . With regard to the factors k _P , k _D and k _{M ,} it is provided, for example, that they depend on the current driving situation, namely on the current speed v of the motor vehicle. In concrete terms, it is provided that the factors k _P and k _D are continuously reduced as the driving speed v increases and become 0 above a certain predetermined driving speed.

Further aspects can be taken into account within the scope of the motor vehicle 1 according to the invention or the method according to the invention. Provision can thus be made for the speed of the rotor 4 to have an upper limit. Furthermore, a maximum possible acceleration of the motor vehicle 1 is also conceivable. Such limitations, in particular of the acceleration, can lead to a limitation of any torsional vibration effects in the drive train 2 . Whether a corresponding acceleration limitation is carried out or the selection of the specific limitation value to which the acceleration is limited can depend in particular on whether the acceleration of the rotor 4 and its direction of rotation have the same or opposite signs, whereby in the first case a limitation is not absolutely necessary . Δα or its sign can be used for checking.

A general advantage associated with the present invention is set forth below. In this way, the acquisition of the machine rotation information 19 provides an additional or alternative database for controlling the drive power of the electrical machine 5 . In addition, the detection of the machine rotation information 19 or the rotational position of the rotor 4 is subject to less inaccuracy than the detection of the wheel rotation information 20 relating to the rotational position of the wheel 6, on the basis of which this control is often carried out in the prior art. This effect is even more serious if the transmission 9 is provided in the drive train 2 . This is explained in somewhat more detail below, a transmission ratio of i _G =i _AS =1/10 being assumed as an example.

The example presented below, in particular the numerical values used for this purpose, are merely exemplary. In concrete terms, it is shown that the rotational position of the rotor 4 is well suited to compensating for torsional vibrations, in contrast to the rotational position of the wheel 6, as a control input variable. For the purpose of explanation, a starting scenario is assumed in which the motor vehicle 1 is currently traveling at a speed v of 2.7 cm/s. With a circumference of the wheels 6 of 2 m, the rotation frequency is 0.0135 revolutions per second. A torsional vibration that typically occurs has a frequency of 5 Hz, which corresponds to a period of 2 s. It therefore takes 0.0027 revolutions of the wheel to run through a complete period of torsional vibration. If wheel rotation detection means 21 includes a gear wheel with 96 flanks provided for detecting the rotational movement of wheel 6, this means that 0.26 flanks are passed through during one period of torsional vibration, so that ultimately a wheel rotation position detected in this way is not suitable as a controlled variable .

If the same assumptions are made and instead the rotational position of the rotor 6 is to be provided as the control input variable, with the gear 9 having a gear ratio i _G =1/10, it takes 0.027 revolutions of the wheel 6 to run through one period of torsional vibration. the machine rotation detection means 13 or the rotary encoder has a resolution of 1.6° in an electrical machine 5 with six pairs of poles, so this rotary encoder has 6.1 edges that are passed through during a period of torsional vibration. You can see the turning point position of the rotor 4, for example in comparison to the rotational position of the wheel 6, is very well suited as a corresponding controlled variable.

Reference List

1

motor vehicle

2

powertrain

3

stator

4

rotor

5

electric machine

6

wheel

7

transmission component

8th

first driveshaft

9

transmission

10

second driveshaft

11

drive axle

12

control device

13

engine rotation detection means

14

drive assembly

15

process step

16

process step

17

process step

18

process step

19

machine rotation information

20

wheel rotation information

21

wheel rotation detecting means

22

graph

23

graph

24

Arrow

25

control signal

26

graph

27

graph

28

process step

29

process step

30

process step

31

Arrow

32

first period

33

second period

34

graph

35

graph

36

accelerator

37

Arrow

38

elasticity information

39

game information

40

driving torque information

41

vehicle control

42

translation information

43

graph

44

Arrow

memes

drive torque

Msoll

drive torque

α rotor

current rotation angle of the rotor

iG

Transmission ratio

αRad

current angle of rotation of the wheel

α*rotor

current relative rotation angle of the rotor

αshould

ideal rotation angle of the rotor

αis

current rotation angle of the rotor

Δα

angular deviation

EAS

Elasticity constant of the transmission components

ΔαM

stress-induced angular deviation

iAS

Transmission ratio of the drive train

SAS

Game

A

amplitude

φ

phase

P

period of oscillation

v

speed of the motor vehicle

kP

P factor

kD

D factor

kI

I factor

t

Time

at)

initial size

e(t)

control input variable

MEM1

first drive torque

MEM2

second drive torque

km

proportionality factor

Claims (10)

Method for operating a drive train (2) of a motor vehicle (1), comprising an electric machine (5) for generating a drive torque M _EM which is transmitted via at least one transmission component (7) of the drive train (2) to at least one wheel (6) of the motor vehicle (1) is transmitted, with a control device (12) generating a control signal (25) by means of which the electrical machine (5) is activated and which describes the drive torque (M _EM ) currently to be generated by the electrical machine (5), thereby characterized in that machine rotation information (19) relating to a current angle of rotation (α _rotor ) and/or a current speed of rotation of a rotor (4) of the electric machine (5) is detected by means of a machine rotation detection means (13), with the control signal (25) being dependent the machine rotation information (19) and/or an input variable determined by means of the machine rotation information (19). procedure after claim 1 , characterized in that wheel rotation information (20) relating to a current angle of rotation (α _Rad ) and/or a current rotational speed of the wheel (6) is detected by means of a wheel rotation detection means (21), with the machine rotation information (19) and the wheel rotation information (20 ) a current relative rotation angle (α* _rotor ) of the rotor (4) is determined, which is the current rotation position of the rotor (4) with respect to the current rotation position of the wheel (6), the control signal (25) depending on the relative rotation angle ( α* _Rotor ) and/or an input variable determined by means of the relative rotation angle (α* _Rotor ). procedure after claim 1 or 2 , characterized in that the control device (12) is used to determine an ideal rotation angle (α _set ) of the rotor (4) when the drive train (2) is in a fault-free state, with the control device (12) being used to calculate an angular deviation (Δα) between a current The angle of rotation (α _actual ) of the rotor (4) and the ideal angle of rotation (α _set ) of the rotor (4) are determined, with the control signal (25) being determined as a function of the angular deviation (Δa) and/or using the angular deviation (Δα). Input variable is generated. Method according to one of the preceding claims, characterized in that for determining the or an ideal rotation angle (α _set ) and/or that within the framework of a regulation specification which is used to generate the control signal (25), - elasticity information (38) which describes an elastic behavior of the transmission components (7) during the transmission of the drive torque (M _EM ), and/or - transmission information (42) which describes a transmission ratio brought about by means of the drive train, in particular by means of a gearbox (9) of the drive train (2). (i _AS ) between the rotor (4) and the wheel (6), and/or - play information (39) which describes a play (S _AS ) present in the drive train during the transmission of the drive torque (M _EM ), and /or - a piece of drive torque information (40) relating to a drive torque (M _set ) specified by the driver is recorded and taken into account. Method according to one of the preceding claims, characterized in that on the basis of the machine rotation information (19) and/or the input variable determined by means of the machine rotation information (19) and by means of the control device (12) it is determined whether in the drive train (2) there is currently a Torsional vibration is present and/or the occurrence of a torsional vibration, in particular with a known oscillation period, is imminent, in which case a parameter of the torsional vibration is determined on the basis of the machine rotation information (19) and/or the input variable determined by means of the machine rotation information (19), wherein the control device (12) uses the parameter to generate the control signal (25) in such a way that a variation over time in the drive torque (M _EM ) at least partially compensates for the torsional vibration. procedure after claim 5 , characterized in that the parameter - a current or expected amplitude (A) and / or - a current or expected phase (φ) and / or - a current or expected oscillation period (P) of the torsional vibration, wherein the electrical Machine (5) is controlled by means of the control signal (25) in such a way that the drive torque (M _EM ) is given a, in particular periodically, changing and dependent on the amplitude (A) and/or the phase (φ) and/or the oscillation period (P ) dependent torque is imposed in such a way that the torsional vibration is damped. procedure after claim 5 or 6 , characterized in that for the generation of the control signal (25) by the control device (12) a PID control algorithm or PD control algorithm with a constant or variable, in particular dependent on the speed (v) of the motor vehicle (1), P-factor ( k _P ) concerning the P-element and a constant or variable, in particular the speed (v) of the motor vehicle dependent, D-factor (k _D ) relating to the D-element is used. Control device set up to carry out a method according to one of the preceding claims. Drive arrangement comprising a drive train (2) of a motor vehicle (1) with an electric machine (5) for generating a drive torque (M _EM ) which is transmitted via at least one transmission component (7) of the drive train (2) to at least one wheel (6) of the motor vehicle (1) is transferrable, wherein a control device (12) of the drive arrangement (14) is set up to generate a control signal (25), by means of which the electric machine (5) can be controlled and which describes the drive torque (M _EM ) to be generated, characterized in that machine rotation information (19) relating to a current rotation angle (α _rotor ) and/or a current rotation speed of a rotor (4) can be detected by means of a machine rotation detection means (13) of the drive arrangement (14), wherein the control signal (25) can be generated as a function of the machine rotation information (19) and/or an input variable determined by means of the machine rotation information (19). Motor vehicle comprising a drive arrangement (14). claim 9 .

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