DE102022203710A1 - Method and computer program for dampening vibrations of a drive train of an electric vehicle, control unit for an electric vehicle, and computer-readable medium - Google Patents

Abstract

The invention relates to a method for dampening vibrations of a drive train (44) of an electric vehicle (20). The drive train (44) has at least one electric machine (24) and a transmission (26), which are operatively connected to one another. The method comprises: controlling the electric machine (24) by means of a control signal which is representative of a predetermined driver desired torque (Mf), the electric machine (24) generating a drive torque (Me) depending on the control signal, the drive torque (Me ) has a vibration torque that is transmitted to the drive torque (Me) by vibrations that arise in the drive train (44) in the torque transmission direction downstream of the electric machine (24); Determining a speed that is representative of a phase speed (ωg) at the transmission (26); Determining at least one property of the oscillation moment depending on the determined speed; Determining a damping moment (MDamp) depending on the determined speed and the oscillation moment such that the oscillation moment can be compensated for by means of the damping moment (MDamp); Modifying the control signal depending on the damping torque (MDamp); and controlling the electrical machine (24) using the modified control signal.

Description

The invention relates to a method and a computer program for dampening vibrations of a drive train of an electric vehicle, a control unit for the electric vehicle, and a computer-readable medium on which the computer program is stored.

An electric vehicle within the meaning of this application has a drive train with an electric machine, a transmission and optionally a differential gear, “differential” for short. The electric machine can be operated as an electric motor and/or generator, in particular as an alternator. If the electric machine is operated as an electric motor, the electric machine can be supplied with energy by means of a drive battery of the hybrid vehicle. If the electric machine is operated as a generator, the electric machine can charge the drive battery of the electric vehicle. Such an electric vehicle can be, for example, a car, a truck, an SUV, a minibus or a bus.

A driver of the electric vehicle can request a driver's desired torque using an accelerator pedal, which can also be referred to as driver's desired torque. A sensor coupled to the acceleration pedal, formerly “gas pedal”, can detect a position of the acceleration pedal and send a corresponding sensor signal to a control unit of the electric vehicle. The control unit can generate a control signal for controlling the electric machine and send it to the electric machine depending on the sensor signal and in particular depending on the driver's desired torque encoded in the sensor signal. Depending on the control signal, the electric machine generates a drive torque, which can also be referred to as drive torque.

The drive torque generally has oscillations, which can be referred to as oscillation torque, which arise in the drive train in the torque transmission direction after the electric machine and which are transmitted to the drive torque, in other words, are impressed on the drive torque. These vibrations can cause the drivetrain to hum. The humming noise can impair driving comfort.

DE 10 2014 204 343 B4 describes a method for detecting the vibrations of the drive train. In particular, the method determines a frequency, an amplitude and an offset (in German: “offset”) of the oscillations.

It is known to reduce the vibrations and/or humming by keeping a clutch, which is fundamentally arranged, for example, in hybrid vehicles and/or in fuel-operated vehicles, in continuous slip mode by means of a continuous slip control. The clutch in continuous slip mode can serve as a damper to dampen the vibrations and thus reduce the hum. Modern electric vehicles, on the other hand, generally do not have such a clutch, which is why the known methods for reducing vibrations using the corresponding clutches are not suitable for these electric vehicles.

It is the object of the invention to provide a method and a computer program for damping vibrations of a drive train of an electric vehicle, which contributes to a high level of driving comfort and in particular a low hum of the drive train of the hybrid vehicle, in particular without using a clutch of the electric vehicle and / or in particular with a Electric vehicle that does not have a clutch. It is a further object of the invention to provide a control unit that processes the method and/or to provide a computer-readable medium on which the computer program is stored.

These tasks are solved by the subject matter of the independent claims. Further embodiments of the invention emerge from the dependent claims and from the following description.

One aspect of the invention relates to a method for dampening vibrations of a drive train of an electric vehicle. The drive train has at least one electric machine and a transmission, which are operatively connected to one another. The method comprises: controlling the electric machine by means of a control signal that is representative of a predetermined driver desired torque, the electric machine generating a drive torque depending on the control signal, the drive torque having a vibration torque caused by vibrations in the drive train in the torque transmission direction after the electric machine, transfers to the drive torque will carry; determining a speed representative of a phase speed at the transmission; Determining at least one property of the oscillation moment depending on the determined speed; Determining a damping moment depending on the determined speed and the oscillation moment in such a way that the oscillation moment can be compensated for by means of the damping moment; Modifying the control signal depending on the damping torque; and controlling the electrical machine using the modified control signal.

Another aspect relates to a control unit for the electric vehicle, which has a processor and a memory that are designed to process the method explained above.

Another aspect relates to a computer program for dampening vibrations of the drive train of the electric vehicle, which, when executed by the control unit of the electric vehicle, causes the control unit to execute the method explained above.

Another aspect concerns a computer-readable medium on which the computer program is stored. The computer-readable medium can be a hard disk, a USB storage device, a RAM, a ROM, an EPROM or a FLASH memory. The computer-readable medium may also be a data communications network, such as the Internet, that allows downloading of program code.

It is to be understood that features of the method as described above and below can also be features of the control unit, the computer program and/or the computer-readable medium and vice versa.

Determining the damping torque depending on the speed, which is representative of the phase speed on the transmission, and depending on the oscillation torque such that the oscillation torque can be compensated for by means of the damping torque, modifying the control signal depending on the damping torque and controlling the electrical machine by means of of the modified control signal make it possible to control the electrical machine in such a way that the drive torque generated by the electrical machine is almost free or ideally free of the vibrations, in particular free of the vibration torque. This causes only small vibrations or, at best, no vibrations at all to be generated in the drive train. This makes it possible to dampen the vibrations of the drive train even without a clutch. This can reduce or even prevent drivetrain hum. This contributes to a high level of driving comfort.

The oscillation, in particular the oscillation moment, in particular the frequency, the amplitude and optionally the offset of the oscillation or the oscillation moment, can, for example, according to the patent specification mentioned at the beginning DE 10 2014 204 343 B4 can be determined using the procedure described. The velocity representative of the phase velocity at the gearbox may be the phase velocity at the gearbox or an angular velocity at the gearbox. The speed can be detected using a speed sensor that is coupled to the transmission. Depending on the speed of the transmission, the speed sensor can generate a sensor signal that is representative of the speed at the transmission. The sensor signal can then be transmitted and received by a damping module of the electric vehicle that processes the method. The attenuation module can be a software module or a hardware module or a combination of software and hardware module. The control unit of the electric vehicle can have the damping module.

The electric machine can, for example, have an electric motor, an inverter and an engine control unit. The electric machine can be operated as an electric motor or as a generator. The drive train can have a differential and two side shafts after the transmission in the torque transmission direction, which connect the differential to wheels, for example front wheels or rear wheels, of the electric vehicle. The differential can be coupled to the transmission via a transmission shaft.

According to one embodiment, the driver's desired torque is specified by a driver of the electric vehicle and the control signal for the electric machine is determined depending on the driver's desired torque. The driver's desired torque can be specified, for example, by a driver of the electric vehicle using the acceleration pedal.

According to one embodiment, the property of the oscillatory moment comprises an amplitude A and/or a frequency f _g of the oscillatory moment.

According to one embodiment, the property of the oscillation torque comprises the frequency f _g of the oscillation torque, an upper limit frequency f _oG and a lower limit frequency f _uG of a bandpass filter being determined depending on the frequency f _g of the oscillation torque, and the damping torque being determined depending on the determined speed by filtering the determined speed using the bandpass filter.

According to one embodiment, the upper limit frequency f _oG and the lower limit frequency f _uG of the bandpass filter are determined depending on the frequency f _g of the oscillation torque such that the upper limit frequency f _oG is greater than the frequency f _g of the oscillation torque and the lower limit frequency f _uG is smaller than are the frequency f _g of the oscillation torque.

According to one embodiment, the property of the oscillatory moment comprises the frequency f _g of the oscillatory moment, a transfer function G _Lead of a lead member being determined depending on the frequency f _g of the oscillatory moment, and the damping moment being determined depending on the determined speed by means of the lead member.

According to one embodiment, a filtered phase speed is determined depending on the determined speed and the damping torque is determined depending on the filtered phase speed. The filtered phase speed can be determined, for example, by filtering the determined speed using a bandpass filter. The bandpass filter can be the bandpass filter explained above, or another bandpass filter. Alternatively, the filtered phase speed can be determined, for example, by filtering the determined speed using a low-pass filter or a high-pass filter.

According to one embodiment, the transfer function G _Lead of the lead element is determined depending on at least one predetermined time constant T ₁ , T ₂ and the time constant T ₁ , T ₂ is specified so that a predetermined phase increase φ _Lead is achieved at the frequency f _g of the oscillation torque becomes.

According to one embodiment, the property of the oscillatory moment comprises the amplitude A and the frequency f _g of the oscillatory moment, a DT1 element being determined depending on the frequency f _g and the amplitude A of the oscillatory moment and the damping moment depending on the phase velocity by means of the DT1 element. Limb is determined.

According to one embodiment, the DT1 element is determined depending on the frequency f _g and the amplitude A of the oscillation torque by determining a time constant T _DT1 of the DT1 element as a function of the frequency f _g of the oscillation torque and a gain factor of the DT1 element as a function of the amplitude A of the oscillation moment is determined.

According to one embodiment, the time constant T _DT1 of the DT1 element is determined depending on a predetermined phase reserve φ _r of the drive train. The predetermined phase reserve φ _r can be, for example, between 45° and 90°, for example approximately or exactly 60°.

• 1 zeigt eine schematische Darstellung eines Ausführungsbeispiels eines Elektrofahrzeugs.
• 2 zeigt ein Ausführungsbeispiel einer Regelung, die auf einen Antriebsstrang des Elektrofahrzeugs gemäß 1 wirkt.
• 3 zeigt ein Ablaufdiagram eines Ausführungsbeispiels eines Verfahrens zum Dämpfen von Schwingungen des Antriebsstrangs des Elektrofahrzeugs gemäß 1.

According to one embodiment, the control signal is modified depending on the damping torque by subtracting the damping torque from the driver's desired torque and encoding a resulting torque in the control signal.

• 1 shows a schematic representation of an exemplary embodiment of an electric vehicle.
• 2 shows an exemplary embodiment of a control system that is based on a drive train of the electric vehicle 1 works.
• 3 shows a flowchart of an exemplary embodiment of a method for dampening vibrations of the drive train of the electric vehicle 1 .

Exemplary embodiments of the invention are described in detail below with reference to the accompanying figures. The reference symbols used in the figures and their meaning are listed in summary form in the list of reference symbols below. Basically, identical or similar parts are given the same reference numbers.

1 shows a schematic representation of an exemplary embodiment of an electric vehicle 20. The electric vehicle 20 can be, for example, a car, a truck, an SUV, a minibus or a bus. Into the special shows 1 a general structure of the electric vehicle 20 with an electric central drive comprising a drive train 44, with a control unit 22 for controlling the central drive, and with wheels 32 which are driven by the central drive.

The drive train 44 has an electric machine 24, a transmission 26 and preferably a differential gear, or differential 40 for short. The transmission 26 is arranged between the electric machine 24 and the differential 40 in the torque transmission direction. The electric machine 24 may have an inverter (not shown) and a motor control unit, in other words motor controller (not shown). The electric machine 24 is in operative connection with the transmission 26. An output of the transmission 26 is connected to the differential 40 via a transmission shaft. The differential 40 is connected to the wheels 32 by side shafts 36 which form an axle 34 of the electric vehicle 20. The wheels 32 may be front wheels or rear wheels of the electric vehicle 20. The drive train 44 has a speed sensor (not shown) on or in the transmission 26. The speed sensor is, for example, coupled to an output of the transmission 26 and is used to detect the speed of the output of the transmission 26.

The electric machine 24 is electrically coupled to a drive battery (not shown) via the inverter. The drive battery can also be referred to as a high-voltage battery. The drive battery is used to operate the electrical machine 24. The drive battery can be, for example, a lithium-ion drive battery.

The control unit 22 may be a general vehicle controller of the electric vehicle 20 and may optionally include the engine controller of the electric machine 24. Alternatively, the control unit 22 can communicate with the engine control of the electric machine. The control unit 22 communicates with an acceleration pedal 23 of the electric machine 24. A driver of the electric vehicle 20 can request a driver's desired torque M _f via the acceleration pedal 23. Depending on the driver's desired torque M _f , the control unit 22 generates a control signal in which the driver's desired torque M _f is coded.

The electric vehicle also has a damping module 28. The damping module 28 communicates with the control unit 22 and/or with the motor control of the electric machine. Alternatively, the damping module 28 can be integrated into the control unit 22 and/or the engine control. The control unit 22 controls the electrical machine 24 using the control signal.

The electric machine 24 has a mass inertia J _e and generates a drive torque M _e in response to receiving the control signal. Without damping by the damping module 28, the drive torque M _e has a vibration torque which is impressed on the drive torque M _e due to vibrations in the drive train 44.

kann die Phasengeschwindigkeit ω_g des Getriebes 26 ermittelt werden. Alternativ kann mittels des Drehzahlsensors eine Winkelgeschwindigkeit des Getriebes 26 gemessen und/oder ermittelt werden.The transmission 26 driven by the electric machine 24 has a mass inertia J _g and generates a transmission torque M _g . A phase φ _g on the transmission 26 and/or a phase speed ω _g of the transmission 26 can be measured and/or determined using the speed sensor. For example, a speed n _g on the transmission 26 can be detected using the speed sensor and using the formula $${\omega }_G=2\times \mathrm{\pi }\times n_G$$

The phase speed ω _g of the transmission 26 can be determined. Alternatively, an angular velocity of the transmission 26 can be measured and/or determined using the speed sensor.

The transmission torque M _g generated by the transmission 26 is transmitted via the differential 40 to the side shafts 36, which represent an output of the drive train 44. The output of the drive train 44 has a mass inertia J _a at the output of the drive train 44, a phase speed ω _a at the output of the drive train 44 and a phase φ _a at the output of the drive train 44 and transmits an output torque M _a to the wheels 32.

In contrast to conventional vehicles with internal combustion engines or hybrid vehicles with internal combustion engines and electric motors, the electric vehicle 20 does not have a clutch. The desired torque is transmitted from the electric machine to the wheels via the gearbox and differential.

2 shows an exemplary embodiment of a control that is applied to the drive train 44 of the electric vehicle 20 according to 1 works. The drive train 44 represents a controlled system of the control system. The damping module 28 is part of the control system and determines a damping torque M _Damp depending on the phase speed ω _g of the transmission 26.

The control and in particular the damping torque M _Damp serve to reduce the vibrations of the drive train 44. In particular, the damping module 28 determines the damping torque M _Damp for damping the vibrations imposed on the transmission 26 by the output of the drive train 44, which is subsequently subtracted from the driver's desired torque M _f by means of a subtraction module 46. The subtraction module 46 sends a resulting torque M _r , which corresponds to the difference between the driver's desired torque M _f and the damping torque M _Damp , to the drive train 44, in particular to the electric machine 24. The electric machine 24 then generates the drive torque M _e , where the drive torque M _e is adjusted for the oscillation torque due to the subtracted damping torque M _Damp . The subtraction module 46 may be a software module or a hardware module or a combination of software and hardware module. The attenuation module 28 may have the subtraction module 46.

The vibrations can also be referred to as torsional vibrations and can be caused, for example, by an elasticity of the side shafts 36 and can be impressed on the drive torque M _e . The oscillations can be described and compensated for by the damping moment M _Damp . The oscillations, in particular the corresponding oscillation moment, in particular a frequency, an amplitude and optionally an offset of the oscillations or the oscillation moment, can, for example, according to the patent specification mentioned at the beginning DE 10 2014 204 343 B4 can be determined using the procedure described.

3 shows a flowchart of an exemplary embodiment of a method for dampening vibrations of the drive train 44 of the electric vehicle 20 according to 1 .

In a step S2, the electric machine 24 is controlled using the control signal, which is representative of the driver's desired torque M _f , which is specified by the driver using the acceleration pedal 23. The electric machine 24 generates the drive torque M _e depending on the control signal, the drive torque M _e having the oscillation torque that is transmitted to the drive torque M e by the vibrations that arise in the drive train 44 in the torque transmission direction downstream of the electric machine ₂₄ .

In a step S4, a speed is determined which is representative of a phase speed ω _g on the transmission 26. This speed can be the phase speed ω _g or an angular speed at the gear 26. The speed, in particular the phase speed ω _g , on the transmission 26 can be determined, for example, using the speed sensor.

In a step S6, at least one property of the oscillation torque is determined depending on the phase speed ω _g on the transmission 26. The property of the oscillatory moment includes, for example, an amplitude A and/or a frequency f _g of the oscillatory moment, and optionally an offset of the oscillatory moment.

In a step S8, the damping torque M _Damp is determined depending on the phase speed ω _g on the gear 26 and the oscillation torque, in particular at least one of the properties of the oscillation torque, in such a way that the oscillation torque can be compensated for by means of the damping torque M _Damp .

The damping moment M _Damp can be determined in at least three different ways, which are explained below:

In a first embodiment, the damping torque M _Damp can be determined by determining an upper limit frequency f _oG and a lower limit frequency f _{uG of a bandpass filter depending on the frequency f g of the oscillation torque and determining the damping torque M Damp depending} on the phase speed on the transmission by filtering the phase velocity ω _g at the gearbox 26 using the bandpass filter.

wobei s die Laplace-Variable ist.A transfer function G _BP of the bandpass filter can be determined and/or dynamically adjusted, for example, using the following formula: $$G_{bP}\left(s\right)=\frac{2\ast \pi \ast s\ast \left(f_{OG}-f_{uG}\right)}{s^2+2\ast \pi \ast s\ast \left(f_{OG}-f_{uG}\right)+4\ast {\pi }^2\ast f_{OG}\ast f_{uG}}$$

where s is the Laplace variable.

A correspondingly filtered phase velocity ω _g,filt results from: $${\omega }_{G,filt}=G_{bP}\left(s\right)\ast {\omega }_G$$

wobei k_BP größer null ist und einen Verstärkungsfaktor zur Konvertierung einer Drehgeschwindigkeit in ein Drehmoment ist. Vorzugsweise werden die obere Grenzfrequenz f_oG und die untere Grenzfrequenz f_uG des Bandpassfilters abhängig von der Frequenz f_g des Schwingungsmoments so ermittelt, dass die obere Grenzfrequenz f_oG größer als die Frequenz f_g des Schwingungsmoments und die untere Grenzfrequenz f_uG kleiner als die Frequenz f_g des Schwingungsmoments sind.The damping moment M _Damp can then be determined as follows: $$M_{Damp}=k_{bP}\ast {\omega }_{G,filt}=k_{bP}\ast G_{bP}\left(s\right)\ast {\omega }_G$$

where k _BP is greater than zero and is a gain factor for converting a rotational speed into a torque. Preferably, the upper limit frequency f _oG and the lower limit frequency f _uG of the bandpass filter are determined depending on the frequency f _g of the oscillation torque in such a way that the upper limit frequency f _oG is greater than the frequency f _g of the oscillation torque and the lower limit frequency f _uG is smaller than the frequency f _g of the oscillation moment.

In a second embodiment, the damping torque M _Damp can be determined by determining a transfer function G _Lead of a lead element depending on the frequency f _g of the oscillation torque and determining the damping torque M _Damp depending on the phase speed ω _g on the gear 26 by means of the lead element. Limb is determined.

wobei die Zeitkonstanten T₁, T₂ so vorgegeben werden können, dass bei der Frequenz f_g des Schwingungsmoments eine vorgegebene Phasenanhebung φ_Lead erzielt wird, beispielsweise gemäß folgender Formeln: $$T_1=\frac{1}{\sqrt{\alpha }\ast {\omega }_g}$$

$$T_2=\alpha \ast T_1$$

mit $$\alpha =\frac{1-\text{sin}\left({\phi }_{Lead}\right)}{1+\text{sin}\left({\phi }_{Lead}\right)}$$

wobei die Phasenanhebung φ_Lead vorgegeben werden kann. Die Phasenanhebung φ_Lead wird vorzugsweise so vorgegeben, dass eine Phasenreserve deutlich größer null wird. Je größer die Phasenreserve ist, desto stabiler ist das Gesamtsystem, insbesondere der Antriebsstrang 44, und umso kleiner sind die Schwingungen. Insbesondere treten die Schwingungen bei der Frequenz f_g auf, wenn eine Gesamtphasenverschiebung φ_Sys des Gesamtsystems bei dieser Frequenz -180° beträgt, also die Phasenreserve φ_r = 180° + φ_Lead = 0 ist. Beispielsweise kann die Phasenanhebung φ_Lead = 60° gewählt werden.The transfer function G _Lead of the lead element can be determined, for example, depending on at least one predetermined time constant T ₁ , T ₂ , for example as follows: $$G_{Lead}\left(s\right)=\frac{T_1\ast s+1}{T_2\ast s+1}$$

where the time constants T ₁ , T ₂ can be specified so that a predetermined phase increase φ _Lead is achieved at the frequency f _g of the oscillation torque, for example according to the following formulas: $$T_1=\frac{1}{\sqrt{\alpha }\ast {\omega }_G}$$

$$T_2=\alpha \ast T_1$$

with $$\alpha =\frac{1-\text{sin}\left({\phi }_{Lead}\right)}{1+\text{sin}\left({\phi }_{Lead}\right)}$$

where the phase increase φ _Lead can be specified. The phase increase φ _Lead is preferably specified so that a phase reserve becomes significantly greater than zero. The larger the phase reserve, the more stable the overall system, in particular the drive train 44, and the smaller the oscillations. In particular, the oscillations occur at the frequency f _g when a total phase shift φ _Sys of the entire system at this frequency is -180°, i.e. the phase reserve φ _r = 180° + φ _Lead = 0. For example, the phase increase φ _Lead = 60° can be selected.

In this second embodiment too, a filtered phase speed ω _{g ,filt can be determined depending on the phase speed ω g} on the gear 26 and the damping torque M _Damp can be determined depending on the filtered phase speed ω _g,filt . The filtered phase velocity ω _g,filt can be determined, for example, by filtering the phase velocity ω _g on the transmission 26 using a bandpass filter. The bandpass filter can be the bandpass explained above filter, or another bandpass filter. Alternatively, the filtered phase velocity ω _g,filt can be determined, for example, by filtering the phase velocity ω _g on the transmission 26 using a low-pass filter or a high-pass filter.

wobei k_Lead ein Verstärkungsfaktor zur Konvertierung einer Drehgeschwindigkeit in ein Drehmoment ist.The damping moment M _Damp can then be determined using the following formula: $$M_{Damp}=k_{Lead}\ast G_{Lead}\left(s\right)\ast {\omega }_{G,filt}=k_{Lead}\ast G_{Lead}\left(s\right)\ast G_{bP}\left(s\right)\ast {\omega }_G$$

where k _Lead is a gain factor for converting rotational speed into torque.

In a third embodiment, the damping torque M _Damp can be determined by determining a transfer function G _DT1 of a DT1 element depending on the frequency f _g and the amplitude A of the oscillation torque and the damping torque M _Damp depending on the phase speed ω _g on the transmission 26 is determined using the DT1 element. The DT1 element can be determined depending on the frequency f _g and the amplitude A of the oscillation torque by determining a time constant T _DT1 of the DT1 element depending on the frequency f _g of the oscillation torque and a gain factor of the DT1 element depending on the amplitude A of the oscillation torque is determined.

mit $$T_{DT1}=\frac{1}{2\ast \pi \ast f_g}\text{tan}\left(\frac{\pi }{2}-{\phi }_r\right)$$

wobei die Zeitkonstante T_DT1 des DT1-Gliedes abhängig von einer vorgegebenen Phasenreserve φ_r des Antriebsstrangs ermittelt wird. Die vorgegebene Phasenreserve φ_r kann beispielsweise zwischen 45° und 90°, beispielsweise ungefähr oder genau 60° sein.The transfer function G _DT1 can be determined, for example, according to the following formulas: $$G_{DT1}\left(s\right)=\frac{s}{T_{DT1}\ast s+1}$$

with $$T_{DT1}=\frac{1}{2\ast \pi \ast f_G}\text{tan}\left(\frac{\pi }{2}-{\phi }_r\right)$$

wherein the time constant T _DT1 of the DT1 element is determined depending on a predetermined phase reserve φ _r of the drive train. The predetermined phase reserve φ _r can be, for example, between 45° and 90°, for example approximately or exactly 60°.

mit $$k_{DT1}>0$$

und/oder mit $$k_{DT1}=\frac{A\ast \sqrt{1+{\left(2\ast \pi \ast f_g\ast T_{DT1}\right)}^2}}{2\ast \pi \ast f_g}$$

wobei k_DT1 ein Verstärkungsfaktor zur Konvertierung einer Drehgeschwindigkeit in ein Drehmoment istThe damping moment M _Damp can then be determined using the following formula: $$M_{Damp}=k_{DT1}\ast G_{DT1}\ast {\omega }_G$$

with $$k_{DT1}>0$$

and/or with $$k_{DT1}=\frac{A\ast \sqrt{1+{\left(2\ast \pi \ast f_G\ast T_{DT1}\right)}^2}}{2\ast \pi \ast f_G}$$

where k _DT1 is a gain factor for converting a rotational speed into a torque

In a step S10, the control signal can be modified depending on the determined damping torque M _Damp . The control signal can be modified depending on the damping torque M _Damp by subtracting the damping torque M _Damp from the driver's desired torque M _f and encoding a resulting torque in the control signal.

In a step S12, the electrical machine can be controlled using the modified control signal.

In addition, it should be noted that “comprising” does not exclude other elements or steps and “one” or “an” does not exclude a multitude. It should also be noted that features or steps that have been described with reference to one of the above exemplary embodiments are also included in Combination with other features or steps of other embodiments described above can be used. Reference symbols in the claims are not to be viewed as a limitation.

Reference symbols

20

Electric vehicle

22

Control unit

23

Accelerator pedal

24

electric machine

26

transmission

28

Damping module

32

wheel

34

axis

36

Side wave

40

differential

42

output shaft

44

Drivetrain

46

Subtraction module

Ms

Driver desired moment

Me

Drive torque

Je

Mass inertia of the electrical machine

Ma

output torque

Yes

Mass inertia on the gearbox

φa

phase at the output

ωa

Phase speed at the output

Mg

Gearbox torque

Jg

Mass inertia of the gearbox

φg

Phase on the gearbox

ωg

Phase speed on the gearbox

ωg,filt

filtered by phase velocity

MDamp

Damping moment

Mr

resulting torque

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The 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

• DE 102014204343 B4 [0005, 0015, 0040]

Claims (15)

Method for damping vibrations of a drive train (44) of an electric vehicle (20), the drive train (44) having at least one electric machine (24) and a transmission (26) which are operatively connected to one another, the method comprising: controlling the electrical Machine (24) by means of a control signal which is representative of a predetermined driver desired torque (Mf), the electric machine (24) generating a drive torque (M _e ) depending on the control signal, the drive torque (M _e ) having an oscillation torque, which is transmitted to the drive torque (M _e ) by vibrations that arise in the drive train (44) in the torque transmission direction downstream of the electric machine (24); determining a speed representative of a phase speed (ω _g ) at the transmission (26); Determining at least one property of the oscillation moment depending on the determined speed; Determining a damping moment (M _Damp ) depending on the determined speed and the oscillation moment such that the oscillation moment can be compensated for by means of the damping moment (M _Damp ); Modifying the control signal depending on the damping torque (M _Damp ) _; and controlling the electrical machine (24) using the modified control signal. Procedure according to Claim 1 , wherein the driver's desired torque (Mf) is specified by a driver of the electric vehicle (20); and the control signal for the electric machine (24) is determined depending on the driver's desired torque (Mf). Method according to one of the preceding claims, wherein the property of the oscillatory moment comprises an amplitude A and/or a frequency f _g of the oscillatory moment. Procedure according to Claim 3 , where the property of the oscillatory moment includes the frequency f _g of the oscillatory moment; Depending on the frequency f _g of the oscillation torque, an upper limit frequency f _oG and a lower limit frequency f _uG of a bandpass filter are determined; and the damping moment (M _Damp ) is determined depending on the determined speed by filtering the determined speed using the bandpass filter. Procedure according to Claim 4 , whereby the upper limit frequency f _oG and the lower limit frequency f _uG of the bandpass filter are determined depending on the frequency f _g of the oscillation torque such that the upper limit frequency f _oG is greater than the frequency f _g of the oscillation torque and the lower limit frequency f _uG is smaller than that Frequency f _g of the oscillation moment. Method according to one of the preceding claims, wherein the characteristic of the oscillatory moment comprises the frequency f _g of the oscillatory moment; Depending on the frequency f _g of the oscillation torque, a transfer function G _Lead of a lead element is determined; and the damping moment (M _Damp ) is determined depending on the determined speed using the lead element. Procedure according to Claim 6 , whereby a filtered phase velocity (ω _g,filt ) is determined depending on the determined speed, and the damping moment (M _Damp ) is determined depending on the filtered phase velocity (ω _g,filt ). Procedure according to one of the Claims 6 or 7 , wherein the transfer function G _Lead of the lead element is determined depending on at least one predetermined time constant T ₁ , T ₂ , and the time constant T ₁ , T ₂ is predetermined such that a predetermined phase increase φ _Lead is achieved at the frequency f _g of the oscillation torque becomes. Procedure according to Claim 3 , where the property of the oscillation moment includes the amplitude A and the frequency f _g of the oscillation moment, and depending on the frequency f _g and the amplitude A of the oscillation moment, a transfer function G _DT1 of a DT1 element is determined, and the damping moment (M _Damp ) depends from the determined speed using the DT1 element. Procedure according to Claim 9 , whereby the transfer function G _DT1 of the DT1 element is determined depending on the frequency f _g and the amplitude A of the oscillation torque by determining a time constant T _DT1 of the DT1 element depending on the frequency f _g of the oscillation torque and an amplification factor of the DT1 element. Link is determined depending on the amplitude A of the oscillation moment. Procedure according to Claim 10 , whereby the time constant T _DT1 of the DT1 element is determined depending on a predetermined phase reserve φ _r of the drive train (44). Method according to one of the preceding claims, wherein the control signal is modified depending on the damping torque (M _Damp ) by subtracting the damping torque (M _Damp ) from the driver's desired torque (Mf) and encoding a resulting torque (M _r ) in the control signal becomes. Control unit for an electric vehicle (20), the control unit (54) having a processor and a memory which are designed to process the method according to one of the preceding claims. Computer program for dampening vibrations of a drive train (44) of an electric vehicle (20), wherein the computer program, when processed by a control unit of the electric vehicle (20), causes the control unit to carry out the method according to one of Claims 1 until 12 processed. Computer-readable medium on which a computer program can be written Claim 14 is stored.

Images