Method for operating vehicle having at least two drive units

Abstract

The invention relates to a method for operating a vehicle having at least two electric drive units (112, 122) (112, 122), in which, when a cost function in a second operating state results in a lower cost than in the first operating state, the first operating state is switched to the second operating state such that no or less torque is provided, the at least two electric drive units (112, 122) have a first operating state, in which torque is jointly provided by the at least two electric drive units (112, 122), and a second operating state, in which at least one of the at least two electric drive units (112, 122) is switched off or the power output thereof is reduced, a first cost variable of the cost function takes into account the load of the drive unit (112, 122) which is not switched off or which has an increased power output.

Description

Technical Field

[0001] The present invention relates to a method for operating a vehicle having at least two drive units, as well as a computing unit, a vehicle, and a computer program for executing the method. Background Art

[0002] The present invention relates to drive devices of vehicles, in particular drive devices for driving, which can be arranged in parallel. These drive devices can drive a single working shaft or a drive shaft via a summing transmission, or two or more axles can be installed in the vehicle, each axle being equipped with an electric drive unit. Summary of the Invention

[0003] According to the present invention, there is provided a method for operating a vehicle having at least two drive units, in particular drive units for driving, with the features of the independent claims, as well as a computing unit, a vehicle, and a computer program for executing the method. Advantageous designs are the subject matter of the dependent claims and the following description.

[0004] The present invention is based on the following measure: when switching from a first operating state, in which torque is provided jointly by at least two drive units, to a second operating state, in which at least one of the at least two drive units is partially loaded or switched off, so that less or no torque is provided, the load of the drive unit that is not switched off or whose load is increased (output power is increased) in the second operating mode is considered as a cost parameter of a cost function, and a switch is made when the cost function in the second operating state results in a lower cost than in the first operating state.

[0005] In other words, the damaging aspects of load increase (Auflastung) are also taken into account, and the shutdown or partial load condition of one or more drive units is associated with the impact of this measure on the service life of the other drive units that are not switched off or whose load is increased. This makes it possible to increase the load of the drive units without affecting their service life.

[0006] The present invention is particularly applicable to electrified vehicles with high power requirements, such as commercial vehicles, construction machinery, etc., whose functions (such as driving functions or working functions) can be achieved by more than one electric drive unit.

[0007] The present invention is particularly applicable to electric drive units for driving, because in this function, power needs to be continuously output for a long time and the power fluctuation is small, so there is no need to frequently switch different operating modes during operation.

[0008] The load can be determined in particular as a load collective (Lastkollektiv) or a stress collective (Beanspruchungskollektiv). In the load collective, the variation over time of influencing variables such as temperature or voltage, for example, can be determined. These variables are collected directly by internal sensors or calculated based on the corresponding operating state.

[0009] According to one design, the load of an unswitched-off drive unit includes future loads (i.e., loads after switching off or generated by switching off) and / or accumulated historical loads (i.e., existing wear). In particular, for a severely damaged or preloaded drive unit, it should be subjected to a lower load in the future in order to avoid shortening the service life as much as possible.

[0010] According to one design, the second cost parameter of the cost function includes the energy requirement of an unswitched-off drive unit in a second operating state. In a vehicle with a plurality of, in particular, electric drive units, in many cases, a drive unit can be switched off or its power output can be reduced without significantly degrading the overall performance of the vehicle. In this case, the power that was originally shared by two (or more) drive units is now mainly borne by a single or fewer drive units. This results in an increased load, but at the same time, it results in operation with higher efficiency, thereby leading to reduced energy consumption or increased efficiency of the entire drive system.

[0011] However, the increased load leads to higher stresses, so if this function is used frequently, the damaging effect on continuously operating components will intensify over the operating time, potentially causing the components to reach the end of their service life prematurely and possibly even failing earlier. The present invention can avoid this.

[0012] In one design, the future load of an unswitched-off or power-increased drive unit is determined based on the power to be output in the second operating state and / or the torque to be output in the second operating state. Power or torque is a key factor characterizing the load of a drive unit.

[0013] In one design, the future load of an unswitched-off or power-increased drive unit is determined based on the previous load. This enables the system to adapt to the personalized usage of the vehicle by utilizing historical load data. In particular, commercial vehicles, construction machinery, etc. are typically used in repetitive operation scenarios. In most cases, the loads occurring in these scenarios do not reach the design limits of the components. Advantageously, the historical load can be taken into account and the future load can be predicted. Thereby enabling the system to perform a personalized shutdown or power reduction for a specific application scenario, thus improving efficiency while fully utilizing the design limits.

[0014] In one design, the future load of the unshutdown or power output increasing drive unit is determined according to at least one operating parameter of the unshutdown or power output increasing drive unit in the first and / or second operating mode. In particular, it includes the actual operating parameters before shutdown or power reduction, or the (predicted) future operating parameters after shutdown or power reduction. Suitable operating parameters are particularly selected from rotational speed, temperature, torque, drive current, voltage, modulation frequency. Considering these operating parameters is advantageous because they can characterize the load of the drive unit.

[0015] In the present invention, both the actual operating parameters and the personalized cumulative losses (or historical cumulative load) of the drive unit can be considered, which advantageously leads to switching between low-load and high-load drive units to achieve load and loss balance of all drive units and further improve the utilization rate of the efficiency improvement potential.

[0016] The computing unit according to the present invention, such as the controller of a vehicle, is particularly configured to execute the method according to the present invention through programming techniques.

[0017] It is also advantageous to implement the method of the present invention in the form of a computer program or a computer program product (including program code for executing all method steps), because this is particularly cost-effective, especially when the controller for executing the program is also used for other tasks and thus already exists. Finally, a machine-readable storage medium storing the above computer program is also provided. The storage media or data carriers suitable for providing computer programs particularly include magnetic, optical, and electronic memories, such as hard disks, flash memories, EEPROMs, DVDs, etc. The program can also be downloaded through a computer network (Internet, intranet, etc.), and the download method can be wired (such as Ethernet) or wireless (such as WLAN, 3G / 4G / 5G / 6G networks, etc.).

[0018] Other advantages and design schemes of the present invention can be derived from the description and the drawings.

[0019] The present invention is schematically illustrated by the embodiments in the drawings and will be described below in conjunction with the drawings. Description of the Drawings

[0020] Figure 1 A vehicle according to an embodiment of the present invention is shown, which has two drive units connected to different axles.

[0021] Figure 2 A vehicle according to another design of the present invention is shown, which has two drive units connected to the same axle through a summing transmission.

[0022] Figure 3 A method according to a design of the present invention is shown in block diagram form. Detailed Embodiments

[0023] In Figure 1 FIG. 1 schematically shows a vehicle 100 according to an embodiment of the present invention. In the illustrated example, the vehicle has two so-called axles 110, 120 as driving devices for traveling, and each axle has two driving wheels respectively. In addition to the illustrated axles, other types of driving devices for traveling can also be used, such as a so-called single-wheel driving device, in which a single wheel is driven by an electric motor.

[0024] Each axle 110, 120 has a transmission unit 111, 121. On the one hand, the transmission unit can act as a differential, and on the other hand, it receives the torque of the electric motors 116, 126 and transmits it to the driving wheels. The electric motors 116, 126 are powered by inverters 115, 125, and the inverters are in turn powered by an energy storage 130, such as a battery. The electric motor 116 and the inverter 115 are part of the driving unit 112 for traveling. The electric motor 126 and the inverter 125 are part of the driving unit 122 for traveling.

[0025] In Figure 2 FIG. 2 shows another embodiment of the vehicle 100', and the main difference from the vehicle 100 according to Figure 1 FIG. 1 lies in the structure of the axle 110'. In Figure 2 FIG. 2, the transmission unit 111' of the axle 110' is connected to two electric motors 116, 126, so that the transmission unit 111' also acts as a summing transmission.

[0026] In Figure 3 FIG. 3 schematically shows a preferred embodiment of the method according to the present invention in the form of a block diagram. In this case, two driving units 112, 122 of the driving device for traveling are controlled by a computing unit configured as a control device 200. For this purpose, one or more operating parameters P are input into the control device 200, and the control device issues a shutdown / reduction request A to one of the driving units 112, 122 in particular. The "shutdown / reduction request" should be understood as a request to shut down the driving unit or reduce the power output by the driving unit.

[0027] As the operating parameter P, in particular, the temperature of one or two electric motors and / or one or two inverters, and the rotational speed and torque of one or two electric motors can be considered.

[0028] In the first block 201, according to the received operating parameter P, it is estimated whether these operating parameters of the remaining driving unit are still within the allowable range or at the allowable limit after one of the two driving units 112, 122 is shut down or the power is reduced. For example, the sum of the previous torques needs to be regarded as the new torque, and the case of temperature rise needs to be considered.

[0029] In particular, the method is continued only if the expected operating parameters after a planned shutdown or power reduction are still within the allowable limits.

[0030] In block 202, the future load of the non-shutdown or power-output-increasing driving drive unit or the load caused by the shutdown / power reduction is determined. In particular, in a repeated operating process, when the load known at a previous time point is already the load known in an operating mode (a second operating mode in which one of the driving drive units has been shut down), this load can be used. In this case, the previously known load S also applies to the new second operating mode.

[0031] This load S can in particular be determined as a load set.

[0032] In the next block 203, the influence of the load S on the service life t L is determined, where as long as the higher load is still below the load limit B, it will cause the service life t pi to be shortened.

[0033] In the last block 204, it is determined whether the newly generated service life t pi will cause the design service life t n to be shortened. If not, the shutdown / reduction request A can be issued.

Claims

1. A method for operating a vehicle (100, 100') having at least two electric drive units (112, 122), wherein, When the cost function in the second operating state results in a lower cost than in the first operating state, switch from the first operating state to the second operating state so as not to provide or to provide less torque. Wherein, in the first operating state, torque is jointly provided by the at least two electric drive units (112, 122), and in the second operating state, at least one of the at least two electric drive units (112, 122) is turned off or its power output is reduced. Wherein, a first cost parameter of the cost function takes into account the load of the drive units (112, 122) that are not turned off or have an increased power output.

2. The method according to claim 1, wherein, The load of the drive units (112, 122) that are not turned off or have an increased power output includes future load and / or accumulated historical load.

3. The method according to claim 2, wherein The future load of the drive units (112, 122) that are not turned off or have an increased power output is determined based on the power to be output and / or the torque to be output in the second operating state.

4. The method according to claim 2 or 3, wherein The future load of the drive units (112, 122) that are not turned off or have an increased power output is determined based on historical load.

5. The method according to any one of claims 2 to 4, wherein, The future load of the drive units (112, 122) that are not turned off or have an increased power output is determined based on at least one operating parameter (P) of the drive units (112, 122) that are not turned off in the first and / or the second operating mode.

6. The method according to claim 5, wherein The at least one operating parameter (P) is selected from: rotational speed, temperature, torque, drive current, voltage, modulation frequency.

7. The method according to any one of the preceding claims, wherein, A second cost parameter of the cost function includes the energy requirement of the drive units (112, 122) that are not turned off or have an increased power output in the second operating state.

8. A computing unit (200), which is configured to perform all method steps of the method according to any one of the preceding claims.

9. A vehicle (100, 100'), which has at least two electric drive units (112, 122) and a computing unit (200) according to claim 8.

10. The vehicle (100’) according to claim 9, wherein, The at least two drive units (112, 122) are connected by a summing transmission (111').

11. The vehicle (100) according to claim 9, wherein, The at least two drive units (112, 122) are connected to different output devices (110, 120).

12. A computer program, which, when running on the computing unit (200) of the vehicle (100, 100') according to any one of claims 9 to 11, causes the computing unit to perform all method steps of the method according to any one of claims 1 to 7.

13. A machine-readable storage medium, on which the computer program according to claim 12 is stored.

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