Motor vehicle for drag torque compensation of a PSM in case of fault

Abstract

Motor vehicle (100) with a drive comprising at least one permanent magnet synchronous machine, abbreviated as PSM (114), as a first traction machine, and a second traction machine, wherein the PSM (114) is configured to initiate an active short circuit (42) in the event of a fault and wherein the PSM (114) is configured to remain coupled to an axle (113) in the active short circuit (42), wherein the motor vehicle (100) has a control device (112) which is designed and configured to control at least the second traction machine in the event of the active short circuit (42) of the PSM (114) in such a way as to at least partially compensate a resistance torque or drag torque of the PSM (114) in the active short circuit (42).

Description

[0001] The invention relates to a motor vehicle. The invention relates to a method for compensating a drag torque or resistance torque of a PSM in an active short circuit. The invention relates to a control device. The invention relates to a computer program product.

[0002] It is known that permanent magnet synchronous machines, abbreviated as PSMs, enter a so-called active short circuit in the event of a fault to prevent damage to the PSM as much as possible. In the event of a fault, passing the highly speed-dependent peak drag torque induced by an active short circuit in the PSM can only be achieved by accepting high driveline vibrations. Starting from a standstill on a low-friction surface, such as slippery surfaces covered in ice and / or snow, can also lead to a blockage of the axle driven by the PSM.

[0003] The object of the connection is to minimize the aforementioned disadvantages and improve driving behavior even in the case of an active short circuit. As of the filing date or the priority date, the applicant has implemented the necessary and technically feasible safety precautions to enable the safe operation of motor vehicles and to enable both drivers and other road users to participate in traffic as safely as possible. Nevertheless, it is the applicant's continuous effort to improve the safety of motor vehicles and their use. Therefore, one object of the invention is to improve the safety of a journey or even of traffic situations.

[0004] The object is achieved in particular by a motor vehicle having the features of claim 1. The object is achieved in particular by a method having the features of claim 8. The object is achieved in particular by a control device having the features of claim 9. The object is achieved in particular by a computer program product having the features of claim 10. Further features and details of the invention emerge from the subclaims, the description and the drawings. Features and details that are described in connection with the motor vehicle according to the invention naturally also apply in connection with the method according to the invention, the computer program product according to the invention and the control device according to the invention. This also applies vice versa, so that with regard to the disclosure of the individual aspects of the invention, reciprocal reference is or can always be made.

[0005] According to one aspect, the problem is solved in particular by a motor vehicle having the features of claim 1.

[0006] In this case, a motor vehicle can have a drive with at least one permanent magnet synchronous machine, abbreviated as PSM, as a first traction machine, and at least one second traction machine that is permanently coupled to an axle. In this case, the PSM can be configured to initiate an active short circuit in the event of a fault, wherein the PSM is further designed and configured to remain coupled to an axle in the active short circuit. In this case, the motor vehicle can have a control device that is designed and configured to control at least the second traction machine in the event of an active short circuit in the PSM in such a way as to at least partially compensate for a resistance torque or drag torque of the PSM in the short circuit. In particular, the second traction machine makes it possible for the drag torque or drag torque of the PSM to be at least partially compensated.In particular, during an active short circuit, for example when a driver submits a driver request by operating the accelerator pedal, not only is a pure driver request transmitted to the control unit, which would then be forwarded to the second traction motor, but a compensation torque is added to this driver request, which can at least partially compensate for the drag torque or resistance torque. This can prevent, in particular, the driver from driving the PSM further along a state curve when accelerating, at least in some configurations, which could even cause drag torque to increase despite the accelerator pedal being operated. This can lead to driveline vibration, for example because the driver takes his foot off the accelerator but then applies it again in a subsequent attempt.These driveline vibrations can be prevented because the at least partial compensation of the drag torque or the resistance torque makes it possible for the driver to be unaware, or virtually unaware, that the PSM is operating in an active short circuit. Furthermore, the vehicle can remain at least partially maneuverable, allowing the driver to at least pull it onto the hard shoulder, to the side of the road, or out of a dangerous situation, such as breaking down at a rail crossing or at an intersection.

[0007] The motor vehicle can be a hybrid vehicle. The motor vehicle can be a fully electric vehicle. Thus, the second traction motor can be a combustion engine or also an electric motor.

[0008] The axle on which the PSM is located or driven by it can be a front or rear axle. The second traction motor can drive the same axle or a different axle. The PSM can remain coupled to the axle in the event of a fault. This means that there is no need to separate the PSM from the axle to decouple the drag torque from the axle in the event of an active short circuit. This can also simplify the design of the PSM on the axle.

[0009] In embodiments, a decoupleable PSM may also be provided, although in some situations it is not decoupled. In such a case, compensation of the drag torque or resistance torque can be at least partially achieved, as described here and elsewhere.

[0010] An active short circuit, also abbreviated to AKS, is a measure in a PSM that can be used to prevent damage when excessive electrical voltages occur. A deliberately induced active short circuit is considered a safe mode for the PSM. For this purpose, the connecting lines in the PSM can be short-circuited, for example, using IGB transistors in the power electronics. The active short circuit can be considered a safe state in a PSM, with a significant advantage being that the system is de-energized during operating situations in the event of a fault. Such a fault can occur, for example, if the axis that is connected or connectable to the PSM rotates at high speeds. This can induce life-threatening voltages in the PSM. The active short circuit creates a resistance or drag torque in the PSM, the magnitude of which can be highly dependent on the speed.With a high-performance PSM axle in an active short-circuit fault, passing the peak AKS torque may not be possible, or only in conjunction with high driveline vibrations, due to the very high resistance moment. This can lead to the driver attempting to drive from a standstill on low-friction surfaces (e.g., ice or snow). These difficulties can be counteracted by the vehicle described here.

[0011] According to one aspect, an original driver request can be determined. In this case, the at least second traction machine can be increased automatically and as needed by the predicted resistance or drag torque of the PSM in the active short circuit. This makes it possible, in particular, to compensate for a drag or drag torque of the PSM in the active short circuit without additional input from the driver. In particular, it is possible to improve comfort for the driver through familiar driving behavior or the familiar relationship between the accelerator pedal and acceleration. Furthermore, a reduction in driveline vibrations can be enabled. Safety-critical driving situations can be avoided by enabling controlled continuation of the journey.

[0012] The driver's request can be an original request that the driver has already entered, for example, by pressing the accelerator pedal to start or continue driving. It can also be provided that the driver's request is adopted, particularly in the control unit, in such a way that the driver is not aware that the control unit has intervened. This can be described as automatic and on-demand. This improves both driving behavior and driving safety.

[0013] According to one aspect, the resistance or drag torque can be calculated. This calculation can be based on at least one of the parameters selected from a voltage, a current, a temperature, one or more speeds or one or more torques. Additionally or alternatively, the actual torque of the PSM can be made available to the control device via a data bus. This allows the driver's command to be adopted, particularly in the control device, in such a way that the driver in particular does not notice that the control device has intervened. This also allows the correct strength for compensation to be set in order to compensate for the drag torque or resistance torque of the PSM in the short circuit, in particular to give the driver the impression of continuing to drive as normally as possible.

[0014] The drag torque is highly dependent on the speed, as well as the geometry and structure of the PSM. Therefore, various preliminary procedures may have been performed to calculate a corresponding compensation torque, for example, in the control unit, in order to control the second traction motor.

[0015] In particular, a flow diagram can be used to calculate the drag torque or resistance torque acting in the PSM using a voltage and / or current. This can be done as directly as possible, particularly via the currents. This is based in particular on the fact that the power loss caused by the drag torque or resistance torque can be compensated by a power supply in the second traction motor. This improves the responsiveness to an active short circuit or speed changes.

[0016] In embodiments, it is particularly provided that a model, for example in the form of a digital twin, as a digital representation of a PSM, is created in order to determine the characteristic curve at different speeds with which the PSM generates drag torques or resistance moments. This model information can be stored in a table. The data can also be interpolated. This data or the table can be stored in the control device in order to use it in the event of an active short circuit in the PSM in order to extract and anticipate the drag torques or resistance moments. This information is converted into control signals, in particular in the control device, or processed into such signals in order to be able to control the second traction machine. This allows compensation of the drag torques or resistance moments in a simplified manner without a measuring device.

[0017] In some embodiments, the information or data can also be stored in a cloud or data center. The calculation of the compensation torques and / or control signals may also be performed externally and sent to the control device for implementation.

[0018] In embodiments, the PSM can be operated externally on a test bench in an active short circuit. Measurements of the drag torque or resistance torque can be performed in order to store this measured data in a table. The data can also be interpolated. This data or the table can be stored in the control device in order to extract and anticipate the drag torques or resistance torques in the event of an active short circuit in the PSM during travel in an active short circuit. This information is converted into control signals or processed into such signals in order to be able to control the second traction machine. This allows for a simplified compensation of the drag torques or resistance torques without the need for a measuring device. The explanations regarding the embodiments with connections to external data centers or clouds apply accordingly.

[0019] Additionally or alternatively, the actual torque of the PSM can be made available to the control unit. This can be done, in particular, via a data bus. With known geometry and structure, the drag torque or resistance torque can also be output by measuring the speed. This can be transmitted via a data connection, such as a data bus, in particular to the control unit, in order to determine a compensation torque. Here, too, the explanations regarding embodiments with connections to external data centers or clouds continue to apply accordingly.

[0020] In some embodiments, the drag torque or resistance torque can be calculated based on the temperature and speed of the PSM. A model calculation can be performed for the temperature development and temperature distribution. This can allow the temperature to provide the most accurate conclusions about the drag torque or resistance torque.

[0021] According to one aspect, a linear behavior can be imposed on the actual torque of the second traction machine. Alternatively or additionally, a nonlinear behavior, in particular a parabolic curve, can be imposed on the actual torque of the second traction machine.

[0022] A linear behavior can be represented, for example, by a linear increase when a drag torque or resistance torque occurs at the beginning of the active short circuit. Alternatively or additionally, a constant range can be represented linearly as long as the torque does not change, for example, because the driver does not press the accelerator pedal. Alternatively or additionally, a linear decrease can be present.

[0023] Nonlinear behavior, particularly a parabolic curve, can occur when the engine speed increases, for example, when the driver presses the accelerator. Immediate driver input can also lead to the increase being grounded into an actual torque to prevent damage to the traction motor. Electric traction motors, in particular, can sometimes reach full speed in milliseconds (ms), which can lead to severe stress on the mechanics and structures. When the engine speed increases, the actual torque can, in particular, partially assume the inverse form of the drag torque or resistance torque, as a compensating torque.

[0024] According to one aspect, the second traction motor can be an electric traction motor. This can react particularly quickly to changes. As already described, it may therefore be necessary to allow a certain slower rise, in particular to avoid damage to the mechanical system.

[0025] According to one aspect, the driver's command can be approximated by summing the actual torque of the PSM, the drag torque or the resistance torque due to the active short circuit, and the actual torque of at least the second traction motor. This allows for the simplest and most direct approximation possible.

[0026] In particular, the actual torque of the PSM, which decreases due to the drag or resistance torques, and the actual torque of the second traction machine are added together in order to approximate the driver's request, in particular to meet it.

[0027] According to one aspect, an impending or threatened active short circuit of the PSM can be sent to the control device in order to initiate compensation by the second traction motor as seamlessly as possible. This can enable a driving course that, in particular, allows the driver to escape dangerous situations or continue to control the vehicle. It is also possible that the driver does not notice from the behavior of the motor vehicle during a journey that a control device has intervened or is intervening to compensate for a drag torque, or that a PSM has entered a fault situation and is therefore in an active short circuit. In this regard, the driver can be informed of this by means of warning information, such as a warning light in the cockpit or via a display on a cockpit screen.

[0028] According to an independent aspect, a method for compensating a drag torque or resistance torque of a PSM in an active short circuit can be implemented. The method can include the step of determining a driver's command. The method can include the step of comparing the driver's command with an actual torque of a PSM as the first traction machine. The method can include the step of adjusting an actual torque of a second traction machine to at least partially compensate for the drag torque or resistance torque of the PSM in an active short circuit.

[0029] The method can be described by the features, properties, and advantages of the motor vehicle, the control device, and the computer program product. This also applies across the category boundaries of method, device, and system. Thus, the motor vehicle, the control device, and the computer program product can also be described by the features, properties, and advantages of the method. For the sake of readability and conciseness, a repetition of all these features, properties, and advantages is omitted.

[0030] According to an independent aspect, a control device may be designed and configured to carry out a method as described elsewhere.

[0031] The control device can be described by the features, properties, and advantages of the motor vehicle, the method, and the computer program product. This also applies across the category boundaries of method, device, and system. Thus, the motor vehicle, the method, and the computer program product can also be described by the features, properties, and advantages of the control device. For reasons of readability and compactness, a repetition of all these features, properties, and advantages is omitted.

[0032] According to an independent aspect, a computer program product can be designed and configured to carry out a method as described elsewhere when executed on a control device, in particular as described elsewhere.

[0033] The computer program product can be described by the features, properties, and advantages of the motor vehicle, the control device, and the method. This also applies across the category boundaries of method, device, and system. Thus, the motor vehicle, the control device, and the computer program product can also be described by the features, properties, and advantages of the computer program product. For the sake of compactness and readability, a repetition of all these features, properties, and advantages is omitted here.

[0034] The computer program product can be designed and configured to be executed on a machine. When the computer program product is executed on the machine, a method can be carried out as described elsewhere. The computer program product is, in particular, machine-readable code and / or an electrical signal that is / are configured to be read by a machine in order to transmit work instructions to a machine, such as to carry out a method of the type described elsewhere. A computer program product can, in particular, be designed as machine-readable code, in particular as an algorithm that can carry out corresponding compensation. Alternatively or additionally, the machine-readable code can also carry out instructions to be able to adapt at least a second and / or a further traction machine.

[0035] A storage medium can comprise a computer program product as described. Alternatively or additionally, the control device can comprise a computer program product as described. The computer program product is designed and configured to be read from the storage medium by the control device in order to carry out the described method. Thus, the storage medium and / or the control device can be described accordingly by the features, properties, and advantages as described and presented for the methods and / or for the computer program product. This also applies vice versa. For reasons of compactness and readability, a repetition of all these features, properties, and advantages is omitted here.

[0036] Further advantages, features, and details of the invention will become apparent from the following description, which describes embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. They show schematically: Fig. 1 shows an embodiment of a motor vehicle; Fig. 2A shows a characteristic curve of a PSM; Fig. 2B is an illustration of an embodiment of a method; Fig. 3 a graphical representation of a driver request according to an embodiment; and Fig. 4 a graphical representation of a driver request according to one embodiment.

[0037] Fig. 1 shows a schematic representation of an embodiment of a motor vehicle 100. An axle 113 is shown, here in the form of a front axle, but the principle can also be applied to a rear axle. Mixed forms can also exist, in which both a front axle and a rear axle can be driven. Wheels 111 are arranged on the axle 113 via wheel suspensions (not shown). The wheels 111 rotate, in particular, at a speed n.

[0038] The wheels 111 can be set into rotation in two ways. A first traction machine is designed as a permanent synchronous machine, abbreviated to PSM 114. This PSM 114 is connected in particular to the axle 113 in such a way that the PSM 114 and the axle 113 remain connected even in the event of a fault in the PSM 114, in which case it is in an active short circuit 42 (see Fig. 3 and Fig. 4) passes over.

[0039] There may be embodiments in which the PSM 114 is designed to be decoupled from the axis 113. However, for the purposes of the following description, it is particularly intended that the PSM 114 is not decoupled from the axis 113, even though it can in principle be designed to do so.

[0040] In addition to the first traction machine as PSM 114, there is, in particular, at least one further traction machine. In the illustrated embodiment, there are, in particular, even two further traction machines: a further electric traction machine 116, and an internal combustion engine 110. The further electric traction machine 116 can also be a PSM 114 or an asynchronous machine, abbreviated to ASM, to name two examples. A hybrid engine can also be provided. The motor vehicle 100 can therefore be a PHEV or BEV vehicle.

[0041] As shown, the internal combustion engine 110 can transmit a torque M to the axle 113 via a shaft-gearbox combination 115. The advantage of electric drives, viewed purely from a mechanical perspective, is that they can transmit a torque M directly to an axle 113, i.e., without such a shaft-gearbox combination 115. Additionally, it is advantageous that electric drives do not convert linear motion into rotational motion, as is the case with most internal combustion engines 110, but rather that a rotational motion can be transmitted directly to an axle 113.

[0042] In order to be able to control the first, second, and here the third traction machine, a control device 112, also referred to as an engine controller, can be configured and connected to the first, second, and third traction machines via a data bus system 117. Control signals from the control device 112, in particular, are transmitted via the data bus system 117 to the PSM 114 and the at least second traction machine, such as the internal combustion engine 110. Control signals from the control device 112 can also be transmitted to the third electric traction machine 116, as a further electric traction machine 116. These control signals can be calculated and generated by a computer program product 120, which runs as machine-readable code on the control device 112. In embodiments, external calculation is also possible, for example, via a cloud or external data centers.

[0043] A schematic and exemplary representation of control signals that can be input into a control device 112 as a driver request 21 are shown exemplary and schematically in the Fig. 3 and Fig. 4 and described in this regard. Before that, Fig. However, in Figure 2A an exemplary characteristic curve 2 of a PSM 114 in the event of a fault is shown and described in order to facilitate the further explanations of the Fig. 3 and Fig. 4 to be able to follow better in terms of understanding.

[0044] Fig. Figure 2A shows a schematic representation of a characteristic curve 2 of a PSM 114. The PSM 114 is described in detail in its function in an exemplary embodiment in the Fig. 1 and described in detail. Characteristic curve 2 is particularly dependent on the torque N of the PSM 114, as a function of the speed n. The design and construction of the PSM 114 play a particularly important role in determining the characteristic curve. However, characteristic curve 2 shows a drag torque, since the torque N drops sharply with the onset of a fault and the resulting active short circuit (the amount increases, however, and the negative sign indicates braking effect). This results in braking behavior in which the driver would attempt to counteract by specifying further accelerator actuations 22 as driver request 21 (see Fig. 3 and Fig. 4). Between a first speed 3 and a second speed 4 there is in particular the critical speed range 5, in which a minimum 1 of a torque 6 is assumed.

[0045] As an example for a PSM 114, a corresponding characteristic curve 2 can be designed, in particular during start-up. The following values ​​​​in particular only reflect the values ​​of an exemplary embodiment of a PSM 114. The torque N can be between 0 and -500 Newton meters (Nm). Further in particular, the torque N can be between 0 and -300 Nm. Further in particular, the torque N can be between 0 and -250 Nm. The speed can be between 0 and 2000 revolutions per minute, further in particular between 0 and 1000 revolutions per minute. The critical range 5 can in particular be between 50 and 400 revolutions per minute, further in particular between 100 and 300 revolutions per minute, further in particular between 150 and 250 revolutions per minute.If the driver is particularly inexperienced, it may happen, especially when starting off on surfaces with low friction coefficients such as snow or ice, that the driver accelerates, driving the PSM 114 further along characteristic curve 2 toward the minimum 1 of torque 6. This further increases the braking effect. This can lead to driveline vibration, which can negatively impact handling and even lead to axle locking.

[0046] Fig. 2B shows a schematic representation of an embodiment of a method 200. The method 200 can be designed to compensate for a drag torque or resistance torque of a PSM 114 in the active short circuit 42. The method can comprise the step of determining 210 a driver request 21. The method 200 can comprise the step of comparing 220 the driver request 21 with an actual torque of a PSM 114 as the first traction machine and the drag torque or resistance torque of the PSM 114 in the active short circuit 42. The method 200 can comprise the step of adapting 220 an actual torque of a second traction machine to at least partially compensate for the drag torque or resistance torque of the PSM 114 located in the active short circuit 42. The method 200 can comprise the step of switching off 240 the second traction machine. These steps are described in connection with the description of the Fig. 3 and Fig. 4 described in detail.

[0047] Fig. 3 shows a schematic graphic representation of a driver request 21 according to one embodiment in the middle diagram 20. Therein, a torque M is specified over time t. In addition to the driver request 21, the actual torque 29 of the PSM 114 is also schematically shown. The actual torque 26 of the second traction machine is also schematically shown. For easier understanding, a second electric traction machine 116 is assumed here. The upper diagram 10 shows a curve 12 of a speed n over time t. The lower diagram 40 shows whether an active short circuit 42 is present over time t. A pure AKS on or AKS off state is plotted.

[0048] In the example shown, at the beginning (t=0 in diagrams 10, 20, 40) of the representation, a curve 12 of a speed n remains constant, as shown in diagram 10. At a first time 11, the fault occurs, which is why the PSM 114 can transition to an active short circuit (AKS-On). In this case, the curve 12 of the speed n initially remains constant (see diagram 10), but the torque M of the PSM 114 drops 31 from a constant level 29 to a second level 32, since with the constant curve 12 of the speed n according to characteristic curve 2, a corresponding torque N is assumed (see Fig. 2). However, the driver's command 21 also remains constant. However, the driver's command 21 is no longer achieved; instead, a difference 27 occurs, since in the exemplary embodiment shown here, the second traction motor is not controlled by the control device 112 to compensate for the drag torque 32 of the PSM 114.

[0049] At a second time 22, the driver's command 21 changes to a higher level 23 through a step increase 22 (diagram 20). This increases the speed n in a continuous increase 14. In particular, the step increase 22 is not implemented instantaneously, but the speed n is increased in a continuous increase 14 to protect the mechanics, although electrical machines can be able to maximize their speed n within milliseconds. By increasing the speed n in a continuous increase 14, the PSM 114 continues along the characteristic curve 2. Here, a case is shown as an example in which the PSM 114 on the characteristic curve 2 in Fig. 2 is arranged to the left of the minimum 6. This results in a parabolic decline 33, at which the minimum 6 of the characteristic curve 2 can be assumed at a third point in time 15. In other embodiments, a value other than the minimum 6 can also be assumed. This depends in particular on operation and the driver's inputs. The control device 110 does not take into account the drag torque in particular. For this reason, the resulting actual torque 52 does not follow the driver's input 21, but rather a difference 28 occurs, whereby the actual torque is represented as the difference between the torque M of the second electric traction machine 116 and that of the PSM 114.

[0050] At the third time 15, the driver brakes, which corresponds to a drop 24 in the driver's command, shown here as an example, down to the level of a standstill 25. As a result, the speed n drops in a continuous drop 16 to a stationary level 18, i.e. with speed n equal to 0. Due to the falling speed n, the actual torque of the PSM 114 on characteristic curve 2 moves back to the left side of characteristic curve 2, through a parabolic rise 34. In particular, the active short circuit 32 is maintained until a fifth time 19, although all components may already have come to a standstill. As a result, all rotational and actual torques 25, 35 and speeds 18 have dropped to zero.

[0051] Fig. Fig. 4 shows a schematic graphic representation of a driver request 21 according to an embodiment in which, contrary to the embodiment in Fig. 3 (the differences are discussed here) an intervention of the control device 110 takes place at the second time 11, whereby an increase 62 is introduced in the second traction machine as electric traction machine 116.

[0052] Accordingly, an internal combustion engine 110 or even a hybrid engine could also be controlled. However, for reasons of readability, this is not repeated here. As a result, the actual torque of the second traction motor increases to a constant level 41 in order to compensate for the drag torque, whereby the actual torque of the PSM 114 drops to level 32. In this case, the control device 112 sends at least one control signal, in particular via the data bus system 117, to the effect that, in addition to the increase for the second traction motor in order to be able to comply with the driver's command 21 (in this case, a constant torque), a compensating torque is also generated in the second traction motor. As a result, the driver's command 21 is kept constant, in particular without the driver noticing any intervention by the control device 112.If the driver's request 21 changes at the second time 13, as previously described, there is an increase 33 in the drag torque (corresponding to a decrease in the torque N in . Fig. 2A to a minimum 6 at the third time 15). This minimum can be the global minimum 1 from Fig. 2A or follow the torque N at the corresponding speed n. If the speed n were increased above the speed n at which the global minimum 1 sets in, the drag torque would decrease again (not shown here). Between the second time 13 and the third time 15, the control device 112 imposes a parabolic curve 43 on the actual torque of the second traction machine in order to compensate for the parabolic drop 33 in the actual torque of the PSM 112. This makes it possible to comply with the driver's request. In particular, a sudden increase, as represented by the driver's request 21, is avoided in order to protect the mechanics. Instead, an increase 22 is accordingly ground in as a continuous, delayed curve.

[0053] The resistance or drag torque can be calculated based on at least one selected from a voltage, a current, a temperature, or one or more torques M or speeds n. Alternatively or additionally, the actual torque of the PSM 114 can be made available to the control device 112.

[0054] At the third time 15, a driver command 21 can lead to a braking operation, which is why the speed n exhibits a continuous decrease 16 (see diagram 10). In particular, the drag torque also decreases in a parabolic manner, which corresponds to an increase 34 in the actual torque of the PSM. This increase can be accounted for by a decrease 44 in the actual torque of the second traction motor through a corresponding control by the control device 112.

[0055] At the fourth time 17, a standstill of the components can be achieved, as in relation to the Fig. 3. At a fifth time 19, the active short circuit 42 is switched off, as described with respect to Fig. 3 described.

[0056] The above explanation of the embodiments describes the present invention exclusively by way of examples. Of course, individual features of the embodiments can be freely combined with one another, provided they are technically feasible, without departing from the scope of the present invention.

Claims

[1] Motor vehicle (100) with a drive, comprising at least one permanent magnet synchronous machine, abbreviated as PSM (114), as a first traction machine, and a second traction machine, wherein the PSM (114) is configured to initiate an active short circuit (42) in the event of a fault and wherein the PSM (114) is configured to remain coupled to an axle (113) in the active short circuit (42), wherein the motor vehicle (100) has a control device (112) which is designed and configured to control at least the second traction machine in the event of the active short circuit (42) of the PSM (114) in such a way as to at least partially compensate for a resistance moment or drag torque of the PSM (114) in the active short circuit (42). [2] Motor vehicle (100) according to claim 1, characterized bythat an original driver request (21) is determined and wherein at least the second traction machine is increased automatically and as needed by the predicted resistance or drag torque of the PSM (114) located in the active short circuit (42). [3] Motor vehicle (100) according to one of claims 1 or 2, characterized by that the resistance or drag torque is calculated based on at least one selected from a voltage, a current, a temperature, one or more speeds (n) or one or more torques (N, M); and / or wherein an actual torque of the PSM (114) is made available to the control device (112). [4] Motor vehicle (100) according to one of the preceding claims, characterized by that a linear behavior is imposed on the actual torque and / or a non-linear behavior, in particular a parabolic curve, is imposed on the actual torque of the second traction machine. [5] Motor vehicle (100) according to one of the preceding claims, characterized by that the second traction machine is an electric traction machine (116). [6] Motor vehicle (100) according to one of the preceding claims, characterized by that the driver's request (21) is approximated by a sum of the actual torque of the PSM (114), the resistance or drag torque due to the active short circuit (42), and the actual torque of the second traction machine; and / or wherein the second traction machine is designed and configured with respect to the PSM (114) to fully compensate for a maximum drag torque or a maximum resistance torque of the PSM (114) in the active short circuit (42). [7] Motor vehicle (100) according to one of the preceding claims, characterized bythat an impending or threatened active short circuit (42) of the PSM (114) is sent to the control device (110) in order to form a compensation by the second traction machine as seamlessly as possible. [8] Method (200) for compensating a drag torque or resistance torque of a PSM (114) in the active short circuit (42), comprising the steps: - determining (210) a driver request (21); - a comparison (220) of the driver's request (21) with an actual torque of a PSM (114) as the first traction machine and the drag torque or resistance torque of the PSM (114) in the active short circuit (42); and - adjusting (220) an actual torque of a second traction machine for at least partially compensating the drag torque or resistance torque of the PSM (42) in the active short circuit. [9] Control device (112) designed and arranged to carry out a method (200) according to claim 8. [10] Computer program product (120) designed and configured to carry out a method (200) according to claim 8 when executed on a control device (112), in particular according to claim 9.

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