WO2019105645A1

WO2019105645A1 - Method for operating a vehicle

Info

Publication number: WO2019105645A1
Application number: PCT/EP2018/078008
Authority: WO
Inventors: Klaus Beulich
Original assignee: Robert Bosch Gmbh
Priority date: 2017-12-01
Filing date: 2018-10-15
Publication date: 2019-06-06
Also published as: DE102017221673A1

Abstract

The invention relates to a method for operating a vehicle (10) with a first driveline (14), a second driveline (20) with a traction battery (26), a fuel cell system (28) and a vehicle control system (12), wherein in normal operation, at least the following method steps are carried out: a) starting the vehicle (10) with the first driveline (14), which is fed from the traction battery (26) and starting up the fuel cell system (28), b) after the fuel cell system (28) has been started up, distributing a torque request to the first driveline (14) and the second driveline (20), c) actuating the first driveline (14) by means of the vehicle control system (12) in generator mode to charge the traction battery (26), wherein c1) the fuel cell system (28) is turned off or c2) the fuel cell system (28) continues to be operated at lower power, d) recharging the traction battery (26) when the vehicle is stationary by actuating the fuel cell system (28) by means of the vehicle control system (12), or e) recharging the traction battery (26) when the vehicle is in motion by actuating the first driveline (14) in generator mode and driving the vehicle (10) by means of the second driveline (20) via the fuel cell system (28).

Description

description

Method for operating a vehicle

Technical area

The invention relates to a method for operating a vehicle having a first drive and a second drive, with a traction battery and a fuel cell system under normal conditions and when system components fail.

State of the art

Autonomous taxis (robotic taxis) are not currently represented on the market to a significant extent. Robotaxis are usually equipped with a battery electric drive. For use in urban areas smaller speeds and thus smaller drive power required. Autonomous taxis such as Robotaxis are like conventional taxis almost around the clock in use, with the daily driving distance of the order of about 300 km. To have a good availability of these vehicles

ensure on the one hand a high battery capacity and on the other hand, a fast charging ability is essential. If the heating of the passenger compartment is removed from the electric storage, this reduces in the cold

Season with correspondingly low outside temperatures, the range is not insignificant.

Autonomous taxis (robotic taxis) have to meet increased demands on the failure safety of the drive in the event of a fault. This requirement is usually met by two redundant drive systems. In the electrical system of fuel cell vehicles, the adaptation of the two drive sources driving battery and fuel cell system to the traction network via DC / DC Transducer realized. However, these converters require space, increase weight and generate losses and costs. Fuel cell systems require an external electrical energy source, for example in the form of a battery, for fast starting.

Presentation of the invention

According to the invention, a method for operating a vehicle,

in particular proposed an autonomously driving vehicle, which has a first drive and a second drive, a driving battery and a fuel cell system and includes a vehicle control, wherein at least the following steps are undergoing: a) starting the vehicle with the first drive, fed from the traction battery is with simultaneous startup of the fuel cell system of the vehicle,

b) after the startup of the fuel cell system there is a distribution of a torque request to the first and the second drive, c) control of the first drive by the vehicle control in

regenerative mode for charging the traction battery, taking

Ci) a shutdown of the fuel cell system or

c ₂ ) a continued operation of the fuel cell system with low power,

d) a recharge the drive battery in the state by controlling the

Fuel cell system by the vehicle control, or

e) recharging the traction battery while driving by driving the first drive in the generator mode and driving the vehicle by the second drive via the fuel cell system.

The mentioned method steps apply to a fault-free normal operation with filled energy storage.

In a further development of the method proposed according to the invention takes place after the process step Ci), after which a shutdown of Fuel cell system is made after closing a first switch, a further supply of the electrical system of the vehicle by the first drive.

Advantageously, in process step c ₂ ), namely during further operation of the fuel cell system with low power, the feeding of the resulting power of the fuel cell system with open first switch in the electrical system of the vehicle.

In the event that deviating from the error-free normal operation with full

Energy storage a failure of the first drive, which includes an inverter and an electric machine should occur should, in a modification of the above method with the method steps a) to d) a first switch for starting the fuel cell system is closed and after its

Start up again, leaving the vehicle alone

powered up fuel cell system is powered.

Falls in the above-mentioned situation in case of failure of the first drive, the fuel cell system, the first switch is closed and the second drive is powered by the traction battery and the vehicle is moved in this way.

In the event of failure of the traction battery, a second switch is closed and the fuel cell system supplied to start it via a DC / DC converter from an on-board battery backup battery, which may be a normal 12V vehicle battery. Once the fuel cell system

has booted, the previously closed second switch is opened again and the fuel cell system of the vehicle powers itself.

If there is a failure of the fuel cell system and / or failure of the second drive of the vehicle, so this is driven and moved by the first drive, which is fed continuously by the traction battery. If, on the other hand, the first drive fails, the first switch is closed and the vehicle is moved via the second drive, which is fed by the traction battery.

In this case, is arranged by a fuel cell system in the

Blocking diode, a power feed back into the fuel cell system

prevented.

Advantages of the invention

The advantages of the solution proposed according to the invention include, inter alia, that in the proposed according to the invention

Operating strategy for an autonomously driving taxi (Robotaxi) only a DC / DC converter for the 12 V electrical system must be used, which brings weight and cost advantages. The onward travel of the autonomously moving vehicle is in case of failure of the two drives by the invention

proposed fault tolerant operating strategy with two separate independent drive systems guaranteed. Advantages over a purely battery-powered autonomously driving vehicle are that in the inventively proposed operating strategy for a vehicle with a traction battery and a fuel cell system, a high availability of the same is ensured by the fact that a quick reloading of

Fuel, especially gaseous hydrogen is possible. Furthermore, the waste heat from the fuel cell system for heating the vehicle interior can advantageously be used without the range of the vehicle being significantly reduced.

Brief description of the drawings

With reference to the drawing, the invention will be described below in more detail.

It shows:

Figure 1 shows the topology of an autonomously driving vehicle with two

independent drive systems, namely a traction battery and a fuel cell system,

Figures 2

to 8 different operating scenarios of the vehicle according to the

Topology according to FIG. 1

variants

The illustration according to FIG. 1 shows a vehicle 10 which comprises a vehicle control 12 to which a driver request 36 is transmitted. The vehicle 10 comprises a first drive 14 which, in the topology according to FIG. 1, comprises a first inverter 16 and a first electric machine 18 which can be operated both in the engine mode and in the generator mode. In the following figures 1-8 denote the

Reference numerals 40 and 42 a first and a second blocking diode.

In addition, the vehicle 10 has a second drive 20, which includes a second inverter 22 and a second electric machine 24, which can also be operated depending on the control by the vehicle controller 12 in the engine mode as well as in the generator mode. The vehicle 10 includes a traction battery 26, which is an electrochemical battery, and as a further drive, a fuel cell system 28, which optionally may be equipped with a compressor 30 and also may include a humidifier, which is not shown here in detail.

By means of a first switch 32 and a second switch 34, which can be switched to their open and their closed position, both the first drive 14 and the second drive 20 as well as the

Energy systems driving battery 26 and fuel cell system 28 together in different combinations, as will be explained below, interconnected or separated.

The fuel cell system 28 includes a blocking diode 38, which at

corresponding position of the first switch 32 and the second switch 34 prevents feedback of electricity into the fuel cell system 28.

For the sake of completeness, it should be noted that the vehicle 10 comprises a DC / DC converter which converts a vehicle electrical system 46 from the drive systems, i. the electrochemical drive battery 26 and the fuel cell system 28 separates. The vehicle electrical system 46 includes an on-board battery backup 56, which is usually a 12 volt battery.

In the scenario shown in Figure 1, the first switch 32 and the second switch 34 are open. The drive of the vehicle 10 via the

Driving battery 26 and the first drive 14, the first inverter 16 and the first electric machine 18 comprising, which is driven in this case in the engine mode. The compressor 30 accommodated in the fuel cell system 28 is supplied in this scenario via the traction battery 26, while the drive of the vehicle 10 in this scenario from the traction battery 26, the fuel cell system 28 is started simultaneously and slowly started up.

FIG. 2 shows the case that the vehicle 10 is driven via the fuel cell system 28. In the scenario shown in Figure 2, both the first switch 32 and the second switch 34 are open and the drive of the vehicle 10 via the powered-up fuel cell system 28 and the second drive 20, the second inverter 22 and the second electrical Engine 24, which is operated in this case by the vehicle controller 12 in the engine mode. In this state alone is that

Fuel cell system 28 active.

Figure 3 shows the drive of the vehicle by both the driving battery 26 and by the fuel cell system 28. Both the first switch 32 and the second switch 34 are open and the drive of the vehicle 10 via the fuel cell system 28, the first drive 14 and simultaneously via the driving battery 26 and the second drive 20. Die

Vehicle control 12 distributes the torque request according to the

Driver request 36 to the first drive 14 and / or the second drive 20th

It provides the sum of the two services provided. The compressor 30, which may optionally be provided in the fuel cell system 28, is supplied autonomously via the fuel cell system 28, which is active. A recharging of the battery can be done in the scenario shown in Figure 3 via the vehicle controller 12, which the second drive 20 in the

Generator mode, so that the traction battery 26 can be charged recuperatively.

FIG. 4 shows a scenario in the event that a failure 48 of the first drive 14 of the vehicle 10 has occurred. According to Figure 4, both the first switch 32 and the second switch 34 are open, the drive of the vehicle 10 via the fuel cell system 28 and the second drive 20, which includes the second inverter 22 and the second electric machine 24, which in this case is controlled in the engine mode by the vehicle control. Also in this case, the optional in

Fuel cell system 28 provided compressor 30 via the

Fuel cell system 28 supplies. In case of failure 48 of the first drive 14 results in a reduced power and reduced dynamics when driving the vehicle 10th

The illustration according to FIG. 5 shows a scenario in which the failure 48 of the first drive 14 and the failure 50 of the first drive 14 occur

Fuel cell system 28 has come. For this case, the first switch 32 is closed via the vehicle controller 12, while the second Switch 34 remains in its open position. The drive of the vehicle via the battery 26, which also supplies the compressor 30 of the fuel cell system 28. Also in this case results for the vehicle 10, a reduced power and a reduced range, since one of the separate drive systems, namely the fuel cell system 28 has failed.

In the scenario illustrated in FIG. 6, a failure 52 of the second drive 20 has occurred. The drive of the vehicle 10 via the preferably designed as an electrochemical battery traction battery 26 and the first drive 14, which includes the first inverter 16 and the first electric machine 18. Also, the compressor 30 is powered by the traction battery 26; the first switch 32 and the second switch 34 are each in their open position. Here, too, a reduced power, thus a reduced speed and a lower achievable range with respect to the operating radius of the vehicle 10, is established in the autonomously driving vehicle 10.

In the scenario shown in Figure 7, the traction battery 26 and the second drive 20 has failed. The first switch 32 is closed while the second switch 34 is open. The drive of the vehicle 10 via the fuel cell system 28 and the first drive 14, which includes the first inverter 16 and the first electric machine 18, which in this case in

Motor operation is controlled. When the vehicle battery 26 fails, the compressor 30 is supplied directly via the fuel cell system 28. But even in this operating condition, reduced driving performance in relation to the achievable maximum speed and a reduced range and a significantly reduced driving dynamics of the vehicle 10 set.

In the scenario illustrated in FIG. 8, a failure 54 of the battery has occurred.

If the traction battery 26 fails, the second switch 34, as shown in Figure 8, closed, whereas the first switch 32 in its

Open position remains. As soon as the fuel cell system 28 has started up and the second switch 34 is open again, the vehicle is driven 10 via the fuel cell system and, for example, via the components of the second drive 20.

As explained above with reference to the described events, if one component of the first drive 14 fails, the start of the first drive 14 occurs

Fuel cell system 28, the first switch 32 is closed. Once the fuel cell system 28 is started up, the first switch 32 is opened again, so that the vehicle 10 thereafter alone from the

Fuel cell system 28 is supplied. In this case, the traction battery 26 serves as a buffer for the supply of the electrical system 46. Restrictions result from the fact that the power of the vehicle is reduced to that of the fuel cell system 28. In the event that there is a failure 50 of the

Fuel cell system comes, the first switch 32 can be closed, so that the traction battery 26 now supplies the second drive 20.

In the event of failure 54 of the battery 26, the second switch 34 is closed and the fuel cell system 28 is powered to start it via the bidirectional DC / DC converter 44 from the electrical system backup battery 56 of the electrical system. This is a conventional 12 V vehicle battery. After starting up the fuel cell system 28, the second switch 34 is opened and the fuel cell system 28 of the vehicle 10 is self-powered.

In case of failure of the fuel cell system 28, the vehicle with

Limited range of the drive battery 26 and the first drive 14 are operated. If, in this state, the failure 48 of the first drive occurs, the first switch 32 is closed and the vehicle is moved via the traction battery 26 and the second drive 20. In this case, the blocking diode 38, which is provided in the fuel cell system 28, prevents a power feedback feed into the fuel cell system 28.

To the reliability of an autonomously driving vehicle 10 as described by the operating strategy, the redundant drives can be additionally combined with a redundant electrical system 46. The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

Claims

claims

A method for operating a vehicle (10) having a first drive (14) and a second drive (20) with a traction battery (26) and a fuel cell system (28) and a vehicle control (12), comprising at least the following method steps: a ) Starting the vehicle (10) with the first drive (14), which is fed from the traction battery (26) and simultaneous startup of the fuel cell system (28)

b) after the startup of the fuel cell system (28), a torque request is distributed to the first drive (14) and / or the second drive (20),

c) control of the first drive (14) by the

Vehicle control (12) in the generator mode for charging the traction battery (26), wherein

Ci) a shutdown of the fuel cell system (28) or c ₂ ) a continued operation of the fuel cell system (28)

low power,

d) recharging the traction battery (26) in the state of the vehicle (10) by activating the fuel cell system (28) by the vehicle control (12),

or

e) recharging the traction battery (26) while driving by driving the first drive (14) in the generator mode and driving the vehicle (10) by the second drive (20) via the fuel cell system (28).

2. The method according to claim 1, characterized in that according to step Ci) after closing a first switch (32) the Vehicle electrical system (46) of the vehicle (10) via the first drive (14) is supplied.

3. The method according to claim 1, characterized in that according to step c ₂ ) with open first switch (32) resulting power of the fuel cell system (28) in the electrical system (46) is fed.

4. The method according to claim 1, characterized in that in the event of a failure (48) of the first drive (14) comprising a first inverter (16) and a first electric machine (18), a first switch (32) for starting the fuel cell system ( 28) is closed and reopened after its startup and the vehicle (10) is powered solely by the fuel cell system (28).

5. The method according to claim 4, characterized in that in case of failure (50) of the fuel cell system (28) of the first switch (32) is closed and the second drive (20) by the traction battery (26) is supplied.

6. The method according to claim 1, characterized in that in case of failure (54) of the traction battery (26), a second switch (34) closed and the fuel cell system (28) to start via a DC / DC converter (44) from a board network Buffer battery (56) is supplied.

7. The method according to claim 6, characterized in that after

Startup of the fuel cell system (28), the second switch (34) is opened and the fuel cell system (28) itself supplies.

8. The method according to claim 1, characterized in that in case of failure (50) of the fuel cell system (28) and / or failure (52) of the second drive (20), the vehicle (10) by the first drive (14) of the driving battery (26) is powered is driven.

9. The method according to claim 8, characterized in that in case of failure (48) of the first drive (14) of the first switch (32) is closed, the vehicle (10) via the second drive (20) of the

Traction battery (26) is powered, is driven.

10. The method according to claim 9, characterized in that by a blocking diode (38) is a power feed back into the

Fuel cell system (28) is prevented.