Method for operating a motor vehicle

Abstract

The invention relates to a method (100) for operating a motor vehicle (10), wherein the motor vehicle (10) has an electrically operable drive machine (11) and a drive store (12) and a fuel cell system (13), the drive store (12) and the fuel cell system (13) being designed to provide energy (EA, EB) for operating the drive machine (11).

Description

[0001] Method for operating a motor vehicle

[0002] The invention relates to a method for operating a motor vehicle, wherein the motor vehicle has an electrically operable drive machine as well as a drive storage unit and a fuel cell system, wherein the drive storage unit and the fuel cell system are configured to provide energy for operating the drive machine.

[0003] Fuel cell-powered vehicles harness the energy of an energy source, such as hydrogen, to convert it into electrical energy using a fuel cell. The electrical energy generated in this way can be directly converted into motion by the electric drive or an electric motor and / or temporarily stored in a traction battery. The electrical storage device or traction battery can enable recuperation, and can also protect the fuel cell from load changes. The abbreviation FC(E)V, for fuel cell (electric) vehicle, is commonly used internationally for such fuel cell-powered vehicles.

[0004] Power delivery to the electric drive from the storage or high-performance storage system is typically very dynamic, while power delivery from the fuel cell or fuel cell system (FCS) is significantly slower. Therefore, the slow power build-up feels comparable to a turbocharger in a combustion engine.

[0005] Against this background, it is an object of the invention to improve a method for operating a motor vehicle. In particular, a method for operating a motor vehicle with a drive storage device and a fuel cell system is to be improved in order to enable differentiation of an additive operation of a drive engine of such a motor vehicle by means of the drive storage device and the fuel cell system. This object is achieved by a method for operating a motor vehicle having the features of claim 1, a control device of a motor vehicle having the features of claim 8, and a motor vehicle having the features of claim 9. The dependent claims relate to advantageous developments of the invention.

[0006] According to a first aspect, a method for operating a motor vehicle is specified, wherein the motor vehicle has an electrically operable drive motor, a drive storage unit, and a fuel cell system, wherein the drive storage unit and the fuel cell system are configured to provide energy for operating the drive motor. The method comprises steps of operating the drive motor using energy provided by the drive storage unit, and generating a signal when a power limit of the drive storage unit is reached and energy is provided to the drive motor by means of the fuel cell system.

[0007] This allows a fuel cell-based power output of the motor vehicle, particularly in the additive, upper power range of the motor vehicle, to be identified and / or provided as a signal, for example for further processing and / or for presentation to a vehicle occupant.

[0008] The electrically operated drive motor is configured to perform mechanical work by converting electrical energy into kinetic energy to drive the motor vehicle. The drive motor can rotate a shaft and thereby drive mechanical devices, such as a transmission, at least one axle, and / or at least one wheel of the motor vehicle, to enable propulsion of the motor vehicle. The electrical energy required for this can be provided by the drive storage unit and / or the fuel cell system.

[0009] The drive storage unit is, in particular, a high-voltage storage unit or accumulator, which can comprise multiple modules with battery cells connected in parallel and series. Such a drive storage unit or such a high-voltage battery can comprise individual battery modules in which individual accumulator cells are combined, which, when connected in series, can deliver a total electrical voltage of several hundred volts. A performance limit of the drive storage unit is reached, in particular, when the maximum electrical energy or power that can be generated or provided by the drive storage unit is delivered. This performance limit can be based on physical conditions and / or predetermined operating limits.

[0010] The fuel cell system comprises, in particular, a plurality of fuel cells, which are arranged, for example, in the form of fuel cell stacks. A fuel cell has at least one anode, which is supplied with a fuel, such as hydrogen, to generate electrical energy, and at least one cathode, which, in cooperation with the at least one anode, is supplied, for example, with ambient air to generate electrical energy in order to supply the atmospheric oxygen contained therein to the fuel cell as an oxidizing agent. To generate electrical energy, the fuel or hydrogen is catalytically oxidized at the anode with the release of electrons to form hydrogen ions. These pass through the electrolyte, usually in the form of a membrane, into the cathode region, where they react with oxygen and electrons conducted to the cathode to form water.Chemical reaction energy is converted into electrical energy, which can be used to convert it into kinetic energy or power in the drive machine.

[0011] To operate the drive motor, electrical energy is provided to the drive motor, in particular based on a power request regarding a mechanical (target) power output, which may be based on a driver request and / or a specification from a control device, in order to convert this energy into mechanical power or kinetic energy. Such a request may include, for example, a target speed, a target acceleration, and / or a target speed profile. The power request can be provided by a driver, for example, using an accelerator pedal.

[0012] Since the provision of energy or power output from the drive storage occurs and can occur dynamically and quickly, the conversion into kinetic energy in the drive motor can be realized correspondingly dynamically and quickly, which is noticeable to a vehicle occupant. This is reflected in particular in a steep gradient of energy or power output from the working storage over time.

[0013] In comparison, the provision or generation of energy or power from the fuel cell system can be significantly slower or exhibit a flatter gradient with regard to energy or power output over time. This resulting slower mechanical power build-up is, particularly in terms of perception for vehicle occupants, comparable to the power build-up of a turbocharger in a combustion engine. As a result, a drop in the power increase can be perceived, particularly during a rapid or strong (target) acceleration phase, when the drive storage has reached its power limit and therefore no more or additional energy can be provided by the drive storage, but the additional energy required by the drive machine to meet the power requirement must be provided by the fuel cell system.

[0014] The invention is based on the idea that, in the event that the provision of electrical energy by the drive storage device has been exhausted, in particular quantitatively, or no additional energy (amount) can be provided by the drive storage device, energy is provided by means of the fuel cell system in order to be able to bring about a further increased or to be increased power output of mechanical power by the drive machine. In order to represent, for example, the reaching of the maximum possible energy output from the drive storage device or the conversion of the maximum available electrical energy by the drive machine and the associated flattening of an acceleration or power output gradient, it is proposed to generate and / or output a signal when the energy or power output by the drive storage device has reached its maximum possible value and the additional power orTo characterize or display the energy required to meet the power requirement or to generate the mechanical (target) power. This allows a signal to be generated and / or output, particularly at a point in time when additional energy is provided by the drive storage unit and fuel cell system, which can be used, for example, to notify a vehicle occupant or driver.

[0015] In one embodiment, energy can be provided to the drive motor by means of the fuel cell system as soon as the power limit of the drive storage is reached. In this case, the fuel cell system, particularly in a further operating mode, can, for example, generate and / or provide energy for the drive storage and only be used to provide energy and the drive motor when the power limit of the drive storage is reached.

[0016] If additional energy provision via the fuel cell system, in addition to the drive storage energy, is only used once the drive storage's performance limit has been reached, a required vehicle acceleration can occur with a flatter gradient or a flatter incline than is possible with energy provision via the drive storage. In this case, the signal can be used, for example, to indicate that a noticeable drop in acceleration is due to the additive use of the drive storage and the fuel cell system, but that a performance limit of the overall energy supply system comprising the drive storage and the fuel cell system has not been reached or has not yet been reached, and that a further, in particular required, mechanical power output by the drive machine, for example in the form of a requested acceleration or speed, is being built up.In some embodiments, the method can comprise the further step of outputting the signal as soon as energy is provided by the fuel cell system. In this case, it can be provided that energy is provided by the fuel cell system, in particular only then and in addition to the drive storage device to the drive machine when or as soon as a power limit of the drive storage device has already been reached. In some embodiments, it can be provided that additional energy is provided by the fuel cell system even before the power limit is reached, in particular in an upper range of a power output capacity of the drive storage device. In this case, the time at which the power limit is reached and the start of the provision of energy by the fuel cell system can differ or coincide.

[0017] In one embodiment, the method comprises the further step of detecting a first value that characterizes an energy output of the fuel cell system. Based on this, it is possible to determine, for example, whether the power limit of the drive storage device has been reached. The power limit can be predetermined as a threshold value, and reaching it can be determined and / or calculated, for example, on the basis of detected measured values ​​or determined on the basis of calculations. This makes it possible to determine the point in time at which, in particular at the latest, energy is to be provided to the drive machine by means of the fuel cell system, in order, for example, to activate the fuel cell system early or in a timely manner.

[0018] In one embodiment, the method comprises the further step of detecting a second value which characterizes an energy output of the fuel cell system. This value can be output, for example, by means of the signal or in addition to the signal. In this case, for example, a measured variable of the fuel cell system can be detected, on the basis of which the output power and / or electrical energy of the fuel cell system to the drive machine can be determined. This value is in particular dynamic or variable and can be taken into account when outputting the signal. In particular, this second value can be output as a proportional and / or percentage indication regarding an energy share of the fuel cell system for providing the currently generated or provided mechanical power.

[0019] In one embodiment, the method comprises the further step of detecting a power demand for the drive motor. The power demand can be generated or detected, for example, by a driver pressing an accelerator pedal and / or by a control device. Based on the power demand, it can be determined how much electrical energy must be provided by the drive storage unit and / or the fuel cell system to generate the required mechanical power.

[0020] In one embodiment, the signal is output as a visual signal. This allows a driver and / or vehicle occupants to be shown the delayed mechanical power buildup, allowing them to visually perceive that the delayed mechanical power buildup is due to the drive storage system reaching its power limit, whereby the requested and / or maximum achievable power of the overall system has not yet been reached and is or can be increased by the fuel cell system.

[0021] In one embodiment, the signal is output via a display device in the vehicle interior. This makes it possible, in particular, to stage or visualize the signal on a display unit, for example, in the display and instrument area of ​​the vehicle, whereby, in particular, a dynamic representation of the increase in power output by the fuel cell system can be staged or visualized.

[0022] According to a further aspect, a control device for a motor vehicle is proposed, wherein the control device is configured to control a motor vehicle according to a method described herein. In particular, the control device is configured to process data from the drive engine, the drive storage unit, and the fuel cell system and / or to provide it therein in order to be able to provide energy to the drive engine via the drive storage unit and / or the fuel cell system depending on a requirement regarding a mechanical power output. Furthermore, the control device is configured to determine a signal for output and / or to transmit this signal to an output and / or display device of the motor vehicle.

[0023] According to a further aspect, a motor vehicle is proposed, comprising an electrically operable drive motor, a drive storage unit, and a fuel cell system, wherein the drive storage unit and the fuel cell system are configured to provide energy for operating the drive motor. The motor vehicle is configured to carry out a method described herein and / or has a control device described herein.

[0024] By means of a motor vehicle designed in this way, the effects and advantages described herein can be used to indicate a delayed acceleration after reaching a power limit of the drive storage and / or a proportion of the energy of the fuel cell system in the mechanical power of the drive engine in order to improve the perception of an acceleration process for a driver and / or vehicle occupants of the motor vehicle.

[0025] Further advantages and possible applications of the invention will become apparent from the following description in conjunction with the figures.

[0026] Fig. 1 shows a schematic representation of an embodiment of a motor vehicle according to the invention.

[0027] Fig. 2 shows a schematic representation of a diagram of power output over time of a motor vehicle according to the invention or based on a method according to the invention for operating a motor vehicle. Fig. 3 shows a schematic flow diagram of an exemplary embodiment of a method according to the invention for operating a motor vehicle.

[0028] Fig. 1 shows a motor vehicle 10 according to an embodiment of the present invention in a schematic representation.

[0029] The motor vehicle 10 has an electrically operable drive motor 11 configured to convert electrical energy EA, EB into kinetic energy or mechanical power LA. This kinetic energy or power LA can be provided by means of a transmission 14 to at least one axle 15 or at least one wheel of the motor vehicle 10 to enable propulsion of the motor vehicle 10.

[0030] In the illustrated embodiment, the motor vehicle 10 has an accelerator pedal 16 configured to detect a driver's request or a power demand Ls for the drive motor 11. The accelerator pedal 16 is connected to a control device 18 configured to process this power demand Ls and operate the electric drive motor 11 in accordance with the power demand Ls.

[0031] To provide electrical energy EA, EB for conversion in the drive engine 11, the motor vehicle 10 has a drive storage unit 12 and a fuel cell system 13. The control device 18 is configured to control the drive storage unit 12 and / or the fuel cell system 13 based on the power requirement Ls, so that they supply the drive engine 11 with electrical energy EA, EB. In addition, the control device 18 is configured to record a first value and a second value, wherein the first value characterizes an energy output EA of the drive storage unit 12 and the second value characterizes an energy output EB of the fuel cell system 13. In addition, the control device 18 is configured to determine, in particular based on the first value, when a power limit of the drive storage unit 12 has been reached and energy EB is being provided to the drive engine 10 by means of the fuel cell system 13.Based on this, the control device 18 can determine or generate a signal and transmit this signal to a display device 17 of the motor vehicle 10 in order to output it, for example, to a driver of the motor vehicle 10.

[0032] Fig. 2 shows a schematic diagram of a power output LA of a drive engine of a motor vehicle 10, as shown in Fig. 1.

[0033] At a time t0, a driver can, here starting from a first power output level Li, output a power request Ls, for example in the form of a torque request, to the drive engine 11 via the accelerator pedal 16. This power request Ls can be processed by the control device 18 and transmitted to the drive engine 11, the drive storage 12 and the fuel cell system 13. In the illustration shown, the electrical energy EA is provided by the drive storage 12 in a time period t0 to ti. At time ti, the power limit G with regard to the maximum electrical energy EA that can be delivered or made available by the drive storage 12 is reached. The power LA delivered by the drive engine 11 is at a second power level L2, but, as can be clearly seen in Fig. 2, has not yet reached the required setpoint Ls.

[0034] In order to achieve the requested target power Ls, as soon as the power limit G of the drive storage 12 is reached, additionally required electrical energy EB is provided by the fuel cell system 13, in particular until the power requirement Ls is met and / or to maintain it, for example until a further power requirement Ls is made or detected by the motor vehicle 10 or the drive machine 11. As a result, a drop in the increase in the power output LA, recognizable in the illustration by the different gradients of the gradients Ai, A2 in the area of ​​energy provision by the drive storage 12 alone (steeper gradient of the gradient Ai) and in the additive energy provision by the drive storage 12 and the fuel cell system (flatter gradient of the gradient A2), can be perceived in the motor vehicle 10.In order to indicate the point at which the power limit G of the working memory 12 is reached and the subsequent additive provision of electrical energy EA, EB from the working memory 12 and the fuel cell system 13, the signal S is generated and / or output, for example by means of the control device 18 and / or the display device 17.

[0035] Fig. 3 shows an embodiment of a method 100 according to the invention for operating a motor vehicle 10, as shown by way of example in Fig. 1.

[0036] In a first step aO, a power requirement Ls for the drive motor 11 of the motor vehicle 10 can be detected, for example, by means of the accelerator pedal 16. In a further step a, the drive motor 11 can be operated using electrical energy EA provided by the drive storage device 12.

[0037] In an optional step a1, a first value can be detected, in particular by means of the control device 18, which characterizes an energy output EA of the drive storage device 12. This can be used, for example, to determine whether the power limit G of the working memory 12 has been reached.

[0038] In a further step b0, in particular as soon as the reaching of the power limit G is detected, electrical energy EB can be provided by the fuel cell system 13 for operating the drive machine 11, in addition to the energy EA of the drive storage 12, for conversion into motive power LA by the drive machine 11. In other exemplary embodiments, the onset or starting time t2 of the provision of energy by means of the fuel cell system 13 can already occur before or after the reaching of the power limit G.

[0039] In a further step b, a signal S is generated when a power limit G of the drive storage 12 is reached and energy EB is provided to the drive machine 11 by means of the fuel cell system 13. In a further optional step b1, a second value can be recorded which characterizes an energy output EB of the fuel cell system 13.

[0040] In a further step c, the signal S can be output as a visual signal S by means of a display device 17 in the vehicle interior of the motor vehicle 10. The signal S can comprise information relating to the values ​​recorded in steps a1, b1, whereby, for example, a specific and / or proportional energy provision EA, EB by the main memory 12 and / or the fuel cell system 13 can be visualized or displayed. This makes it possible to display a differentiation of an additive energy provision EA, EB by the main memory 12 and the fuel cell system 13 in order to make a delayed power build-up visually perceptible and thereby improve the driver's perception of the motor vehicle 10.

[0041] LIST OF REFERENCE SYMBOLS

[0042] 10 motor vehicle

[0043] 11 Drive machine

[0044] 12 drive storage

[0045] 13 Fuel cell system

[0046] 14 gearboxes

[0047] 15 axle or wheel

[0048] 16 Accelerator pedal

[0049] 17 Display device

[0050] 18 Control device

[0051] 100 procedures

[0052] Ai, Ä2 Gradients of power output by prime mover

[0053] EA electrical energy provided by drive storage

[0054] EB electrical energy provided by fuel cell system

[0055] G Performance limit of the drive storage

[0056] LA Power output by prime mover

[0057] Ls power requirement for or on the drive machine

[0058] Li, L2 Power output level of the prime mover

[0059] S Signal ac Steps t Time

Claims

CLAIMS 1. A method (100) for operating a motor vehicle (10), wherein the motor vehicle (10) has an electrically operable drive machine (11) as well as a drive storage device (12) and a fuel cell system (13), wherein the drive storage device (12) and the fuel cell system (13) are configured to provide energy (EA, EB) for operating the drive machine (11), comprising the following steps: a) operating the drive machine (11) by means of energy (EA) provided by the drive storage device (12); b) generating a signal (S) when a power limit (G) of the drive storage device (12) is reached and energy (EB) is provided to the drive machine (11) by means of the fuel cell system (13).

2. Method (100) according to claim 1, comprising the further step: bO) providing energy (EB) by means of the fuel cell system (13) for the drive machine (11) as soon as the power limit (G) of the drive storage (12) is reached.

3. Method (100) according to one of the preceding claims, comprising the further step: a1) detecting a first value which characterizes energy output (EA) of the drive storage (12).

4. Method (100) according to one of the preceding claims, comprising the further step: b1) detecting a second value which characterizes an energy output (EB) of the fuel cell system (13).

5. Method (100) according to one of the preceding claims, comprising the further step: aO) detecting a power requirement (Ls) for the drive machine (11).

6. Method (100) according to one of the preceding claims, wherein the signal (S) is output as a visual signal.

7. Method (100) according to one of the preceding claims, wherein the signal (S) is output by means of a display device (17) in the vehicle interior of the motor vehicle (10).

8. Control device (18) for a motor vehicle (10), wherein the control device (18) is configured to control a motor vehicle (10) according to a method (100) according to at least one of the preceding claims.

9. Motor vehicle (10), comprising an electrically operable drive machine (11) and a drive storage device (12), a fuel cell system (12), wherein the drive storage device (12) and the fuel cell system (13) are designed to provide electrical energy (EA, EB) for operating the drive machine (11) and the motor vehicle (10) is designed to carry out a method (100) according to at least one of the preceding claims and / or has a control device (18) according to the preceding claim.

Images