阅读说明：本技术 用于运行电动或混动车辆的方法以及电动或混动车辆 (Method for operating an electric or hybrid vehicle and electric or hybrid vehicle ) 是由 L.施勒德 于 2020-02-07 设计创作，主要内容包括：本发明涉及一种用于运行电动或混动车辆(2)的方法以及电动或混动车辆。车辆(2)具有车载网络(4),其带有电气传动系(6)且带有电存储器(8),其中,车载网络(4)具有开关(10),用于电存储器(8)和传动系(6)的电气分离和连接,其中,车载网络(4)具有电容器(12),其可预充电,用于在与电存储器(8)连接时保护传动系(6),并且其中,车载网络(4)具有预充电电路(14),用于在预充电运行中预充电电容器(12)。预充电运行在起动事件(S)中被激活,起动事件由用户在车辆(2)开始运转时以及在操纵车辆(2)的点火部(16)之前触发。另外说明了相应的电动或混动车辆(2)。(The invention relates to a method for operating an electric or hybrid vehicle (2) and to an electric or hybrid vehicle. The vehicle (2) has an on-board network (4) having an electrical drive train (6) and having an electrical storage device (8), wherein the on-board network (4) has a switch (10) for electrically separating and connecting the electrical storage device (8) and the drive train (6), wherein the on-board network (4) has a capacitor (12) which can be precharged for protecting the drive train (6) when connected to the electrical storage device (8), and wherein the on-board network (4) has a precharge circuit (14) for precharging the capacitor (12) in a precharge operation. The pre-charging operation is activated in a start event (S) which is triggered by a user when the vehicle (2) is started and before the ignition (16) of the vehicle (2) is actuated. A corresponding electric or hybrid vehicle (2) is also described.)

1. Method for operating an electric or hybrid vehicle (2) having an on-board network (4) with an electric drive train (6) and with an electric accumulator (8),

-wherein the on-board network (4) has a switch (10) for electrical disconnection and connection of the electrical storage (8) and the drive train (6),

-wherein the on-board network (4) has a capacitor (12) that can be pre-charged for protecting the drive train (6) when connected with the electrical storage (8),

-wherein the vehicle-mounted network (4) has a pre-charging circuit (14) for pre-charging the capacitor (12) in a pre-charging operation,

-wherein the pre-charging operation is activated in a start event (S) triggered by a user when the vehicle (2) starts to operate and before an ignition (16) of the vehicle (2) is operated.

2. Method according to claim 1, wherein the starting event (S) is the opening of a door (22), in particular a driver door, of the vehicle (2) and is identified by means of a door switch (24) of the door (22).

3. Method according to claim 1 or 2, wherein the starting event (S) is an unlocking of the vehicle (2).

4. A method according to any one of claims 1 to 3, wherein said start event (S) is the approach of said user to said vehicle (2).

5. Method according to any of claims 1 to 4, wherein the pre-charging operation is activated when the ignition (16) is operated, provided that the pre-charging operation has not been activated before.

6. The method according to any one of claims 1 to 5, wherein the capacitor (12) is integrated into an inverter (26) configured for converting a direct voltage of the electrical storage (8) into an alternating voltage for an electric machine (28) of the drive train (6).

7. Method according to any of claims 1 to 6, wherein the on-board network (4) has an operating voltage (Ub) of at least 400V.

8. The method according to any one of claims 1 to 7, wherein in the precharge operation the capacitor (12) is precharged for a precharge time (t-v), the precharge time being longer than 1 s.

9. Method according to one of claims 1 to 8, wherein the capacitor (12) is precharged with a current (I) of maximally 1A in the precharge operation.

10. The method of any one of claims 1 to 9, wherein the pre-charge circuit (14) has a pre-charge resistance (36) with a resistance value of at least 100 Ohm.

11. An electric or hybrid vehicle (2) having an on-board network (4) with an electric drive train (6) and with an electric memory (8) and with a controller (18),

-wherein the on-board network (4) has a switch (10) for electrical disconnection and connection of the electrical storage (8) and the drive train (6),

-wherein the on-board network (4) has a capacitor (12) that can be pre-charged for protecting the drive train (6) when connected with the electrical storage (8),

-wherein the vehicle-mounted network (4) has a pre-charging circuit (14) for pre-charging the capacitor (12) in a pre-charging operation,

-wherein the controller (18) is configured such that it activates the pre-charging operation in a start event (S) triggered by a user when the vehicle (2) starts to operate and before the ignition (16) is operated.

Technical Field

The invention relates to a method for operating an electric or hybrid vehicle and to a corresponding electric or hybrid vehicle.

Background

Electric or hybrid vehicles (vehicle for short) have an electric drive train (antitriebstrang) with an electric machine for driving the vehicle. The drive train and thus the electric machine are supplied with electrical energy by an electrical accumulator (elektrospecher). The electrical storage device is dimensioned accordingly and is connected to the drive train via a correspondingly designed vehicle electrical system (Bordnetz).

High currents may occur when electrically connecting the drive train and the electrical storage device, which may lead to damage of the drive train or individual electrical components therein, in particular of the contactors (Schuetz) or switches in general. This is the case in particular if the on-board system contains capacitors, for example filter capacitors (filterkondenserters) or energy buffer capacitors (energy snubber capacitors), as part of an inverter (Wechselrichter) in the on-board system. To avoid damage, the capacitor may be precharged (vorladen).

It is desirable here to precharge the capacitor as quickly as possible in order to prepare the vehicle for starting as quickly as possible, so that it can then also be driven. But this is subject to a correspondingly as short as possible precharge time. However, the current must be correspondingly high during precharging, which is conditioned by the corresponding design of the participating components (for example, the precharging resistor). In addition, high heat losses are generally also produced in the case of high currents.

DE 102017201657 a1 describes a vehicle with a high-voltage energy supply network, which has a capacitor that can be precharged by means of a precharge resistor. A variant is also described in which the pre-charge resistor is replaced by an inductance associated with a diode. This reduces losses during precharging, which in turn results in less waste heat being generated.

It is described in DE 102015203912 a1 that a longer delay is produced due to the dimensioning of the capacitor applied there. In order to keep the time for the precharging of the capacitor as low as possible, a specially controlled power supply is applied for the precharging.

Disclosure of Invention

Against this background, it is an object of the invention to improve precharging in electric or hybrid vehicles. In this respect, an improved method for operating an electric or hybrid vehicle and such an electric or hybrid vehicle should be specified.

According to the invention, this object is achieved by a method having the features according to claim 1 and by an electric or hybrid vehicle having the features according to claim 11. Advantageous embodiments, developments and variants are the subject matter of the dependent claims. The embodiments associated with the method are also expressly applicable here to electric or hybrid vehicles and vice versa.

The method is used for operating an electric or hybrid vehicle, which is only referred to as a vehicle in the following. The vehicle has an on-board network with an electric drive train and with an electric storage. The drive train and the electrical storage are thus part of the on-board network. The on-board network has at least one switch for electrically disconnecting and connecting the electrical storage device to the drive train. The on-board network additionally has a capacitor, which can be precharged, for protecting the drive train and in particular also the switches when connected with the electrical storage. In order to precharge the capacitor in the precharge mode, the vehicle-mounted network has a precharge circuit. Within the scope of the method, the precharging operation is activated during a start event (starteignis) which is triggered by a user when the vehicle is started (inbeibnahme) and before the ignition (zuendongg) of the vehicle is actuated. More specifically, the method is thus a method for pre-charging a capacitor in an electric or hybrid vehicle. The start of operation is understood in particular to mean an event which has to be triggered by a corresponding action by the user in order to bring the vehicle from a parking operation (parkbetrib) into a driving operation.

The capacitor in particular completes the precharging and is referred to as "precharged" if it is charged to a charge of at least 90%, that is to say has at least 90% of the total charge of the capacitor. The precharge time indicates that the initially uncharged capacitor is charged to 90% of its total charge after that time. Only when the capacitor is precharged, the switch is switched and the electrical storage is electrically connected to the drive train and in particular to the inverter of the drive train in order to drive the vehicle.

In order to carry out the method, the vehicle has a controller which carries out the respective steps directly or indirectly via one or more further controllers and for which the respective components of the vehicle are appropriately controlled. In particular, the controller is at least configured such that it activates the precharge operation in a start event. For this purpose, the control unit itself recognizes the start event or receives a corresponding signal from a corresponding component or other control unit. Preferably, the controller is a battery management module and is itself integrated into the electrical memory and is coupled here in particular to a data bus in order to exchange control signals with other components or controllers.

The core idea of the invention is, in particular, not just to keep the precharging time as short as possible, but rather to extend it significantly, in order to reduce the electrical requirements for the components involved and in particular to be able to select it significantly more cost-effectively and also more space-saving. The precharging time is thereby extended, i.e., the starting event for the precharging operation is not just the actuation of the selection ignition, but rather a temporally preceding event.

The term "actuation of the ignition" is understood to mean in particular the actuation of a start key, starter (initiator), start button, etc. by a user in order to prepare the vehicle for driving. In this case, the motor is not necessarily also started directly by actuating the ignition, since the capacitor may not yet be precharged. The actuation of the ignition, in turn, initiates a start-up procedure, at the end of which, in particular, the electrical storage is electrically connected to the drive train by switching the switch. It is then possible to start and run with the electric machine and thus with the vehicle.

Of course, the "actuation of the ignition" is a clear indication to the user that the vehicle is to be operated and is therefore suitable in principle as a start signal. However, it is disadvantageous here that little time remains until the start of the actual driving, since an excessively long delay for the start of the precharging operation of the capacitor is unacceptable from the actuation of the ignition and results in a corresponding loss of comfort. Therefore, for example, a maximum of 1s is available from the actuation of the ignition in order to precharge the capacitor. However, it is currently recognized that other events are also triggered by the user before the ignition is actuated when the vehicle is started, which indicate, with sufficient reliability, that the vehicle is started as soon as possible. One of these events is used as a start event and is recognized in the context of the method, in particular, by means of a suitable sensor.

In principle a large number of events are conceivable and suitable as starting events. It is important, in particular, that the starting event typically takes place before the actuation of the ignition and indicates with sufficient probability that the vehicle actually starts running. A "sufficient possibility" is understood to mean, in particular, that the start signal is actually triggered in at least 50% of the cases in the operating range and then is actually followed by the actuation of the ignition. In this case, however, in particular, in certain areas, a misinterpretation (fehlinterpretion) is possible in principle, so that a start of operation is erroneously inferred when a start event is detected, although the user does not expect this and the start event is triggered in another connection. Then the precharge operation is unnecessarily activated at all and the capacitor is unnecessarily charged, but this is not a problem in itself. In a suitable embodiment, the vehicle has a discharge circuit which then discharges the capacitor again during the discharge operation, in particular if the ignition is not actuated within a defined time period, for example 15 minutes.

In a preferred embodiment, the starting event is the opening of a door of the vehicle, in particular of a driver's door, and is detected by means of a door switch of the door. This observation is based on the fact that the opening of the door is in each case carried out at certain time intervals before the actuation of the ignition. The precharging time is therefore significantly longer than the activation from the actuation of the ignition, and is typically several seconds. It is currently concluded based on the opening of the door that the vehicle should be driven next. This is particularly reasonable in the case of a driver's door being open, since this event usually indicates that the user of the vehicle also wants to start it immediately. The opening is also expediently distinguished from the leaving for the opening of the entering vehicle, for example by determining whether the driving operation was active or the vehicle was in a parking operation shortly before.

In order to recognize the opening of the door, a door switch is used, which is preferably part of the vehicle anyway and has been used for the control of other tasks, for example for activating interior space lighting. The door switch is, for example, a mechanical or optical sensor which is arranged in the door frame of the vehicle and is activated when the door is opened. The gate switch is connected to the controller, in particular in terms of signaling, in such a way that it then activates the precharge operation in response to the opening of the gate.

In a further preferred embodiment, the starting event is the unlocking of the vehicle. Unlocking usually takes place before the door is opened, so that the precharging time is further extended in this case. Unlocking is typically effected by the user and, for example, by means of a key or a remote control (Fernbedienung). In a variant, the unlocking is effected automatically, for example when the user approaches the vehicle and this is recognized by the vehicle (for example by means of a camera, a distance sensor or a radio transmitter). For example, the vehicle recognizes the user's smartphone or RFID tag, which then functions as a key accordingly.

In a further preferred embodiment, the start event is the approach of a user to the vehicle. This in turn lengthens the precharging time, but the actual start of the vehicle is typically less likely to start in this case than in the case of the described design. This approach is recognized, for example, by the vehicle as described above in connection with the automatic unlocking.

In contrast to the situation described above in which the precharging operation is unnecessarily activated, there is also the possibility in principle that a start event is not triggered, for example because the respective sensor is defective or the start event is bypassed by the user. For example, in the case of boarding via a passenger door, the door switch in the driver door is not triggered, so that the opening of the driver door fails. In order to also precharge the capacitor in such a case, in a preferred embodiment the precharge operation is activated when the ignition is actuated, provided that the precharge operation has not been activated before. It can therefore be said that the actuation of the ignition is retroactively used as a relatively reliable indicator for the actual start of operation. This is achieved, for example, by the fact that, when the ignition is actuated, a corresponding signal is sent to the controller and it is then checked whether the precharge operation is activated and, if this is not the case, it is activated. Since the precharging circuit is here, however, designed in particular for a longer precharging time than is expected to be available even after the actuation of the ignition, a premature start of travel, which may lead to damage, is expediently delayed accordingly by the control unit or prompted to the user.

Preferably, the capacitor is integrated into an inverter, which is designed to convert the direct voltage of the electrical storage device into an alternating voltage for the electric machine of the drive train. The capacitors are also referred to herein as intermediate circuit capacitors (zwischenkreiskondensators) and in particular form the input capacitance of the inverter. The capacitors in the inverter are used primarily as balancing elements (ausgleichsgried) or energy buffers in order to improve the conversion of the direct voltage into alternating voltage and to decouple the electrical storage from the harmonic oscillations (Oberschwingung) of the inverter caused by operation. The capacitor is therefore fundamentally different from, for example, a capacitor which is used as an energy buffer or filter for small consumers (for example interior lighting, entertainment systems or auxiliary systems), in particular for applications in low-voltage networks.

Due to the application associated with the drive train of an electric or hybrid vehicle, the capacitor is suitably dimensioned accordingly and is therefore also referred to as a power capacitor. The capacitor suitably has a capacitance in the range 0.001F to 1F. The inverter is in particular part of the power electronics which in turn are part of the drive train and which usually arrange the energy from the electrical storage for utilization by the electric machine.

The electrical storage device has, in particular, a plurality of batteries for storing electrical energy. In addition, the electrical storage device has, in particular, two interfaces via which electrical energy can be drawn from the electrical storage device (in particular a battery). The interface is accordingly a power interface and is designed for correspondingly high voltages and currents and is connected to a battery. The switches for disconnecting and connecting the electrical storage device and the drive train are suitably designed as power switches and preferably have two contactors (one for each of the interfaces) in order to disconnect them from the remaining on-board system or to connect them to the remaining on-board system. In principle, a design with only one contact at one of the interfaces is also suitable, and then, without any restriction on versatility, it is assumed that both interfaces are fixed by means of contacts. The switch is suitably integrated into the electrical memory. The switch is in particular connected to the controller and is also switched by it. Normally, the switch is only closed and the electrical storage is thus electrically connected to the drive train if the capacitor has been precharged, i.e. charged to at least 90%, in particular.

In a preferred embodiment, the on-board system has an operating voltage of at least 400V. Such an on-board system is also referred to as a high-voltage on-board system. The electrical storage device provides a corresponding voltage, which then has to be switched on by the switch when connecting to the drive train. In the case of a capacitor which is not precharged, such a high voltage would lead to a strong current peak, so that the uncharged capacitor effectively produces a short-circuit of the electrical storage device at the moment of connection. Whereby switches and other components, especially the entire power electronics, can potentially be damaged.

The important advantage of the invention is, in particular, that the precharging operation is activated significantly earlier than if it were started in response to an actuation of the ignition. As a result, a correspondingly longer precharging time is available as described until the start of the actual driving. In a preferred embodiment, the capacitor is precharged in the precharge mode for a precharge time longer than 1s and preferably even at least 2 s. Preferably, however, the precharge time is at most 5s, in particular because it is often not determined how long the manipulation of the ignition is accurately delayed with respect to the starting event.

Various designs are suitable for the precharge circuit. In a first variant, the precharging circuit has a precharging switch, in particular a contactor or relay (Relais), and a precharging resistor, which are connected in series with one another in the precharging branch (vorladezweight). The pre-charging branch is in turn connected in parallel with a switch, that is to say in particular with one of the contactors of one of the interfaces for the electrical memory. When the precharge operation is activated, the precharge switch is then closed and the switch is bypassed, so that the capacitor is charged via the precharge resistor. In a second variant, the precharging circuit likewise has a precharging branch, but this time with a direct-current voltage converter, also referred to as a DC/DC converter, which is activated in the precharging mode and has a precharging resistor via which the capacitor is then charged analogously to the first variant. Further variants are conceivable and equally suitable.

The extended precharging time enables a reduction of the electrical requirements and thus a significantly more flexible design of the various components, in particular of the precharging circuit. In particular, it is now possible to use smaller charging currents due to the extended precharging time and thus to advantageously use particularly cost-effective and space-saving components. In a preferred embodiment, the capacitor is therefore precharged with a current of at most 1A during the precharge operation. The requirements for the components described above (precharge switch, precharge resistor and dc voltage converter) are accordingly reduced thereby. Whereas in the case of shorter precharging times () of, for example, only 0.5s, currents of approximately 10A are typically reached, i.e. usually by an order of magnitude.

Due to the extended precharging time, too, it is now possible to use significantly larger, i.e. higher-ohmic, precharging resistors, in particular also in order to reduce the current for precharging. In a preferred embodiment, the precharge circuit has a precharge resistance with a resistance value of at least 100Ohm, particularly preferably at least 1 kOhm. Conversely, a precharge resistance of about 50Ohm would be required with a short precharge time below 1 s. The upper limit for the precharging resistance results in particular from the maximum permissible precharging time.

The increased pre-charge resistance and the reduced current during the pre-charging have the particular advantage, inter alia, that the heat losses during the pre-charging are also reduced, since they are proportional to the square of the current, but only simply to the resistance value of the pre-charge resistance. On the one hand, this saves energy for driving, which facilitates the stroke length for the vehicle, and on the other hand, the thermal management of the precharging circuit is significantly simpler, since less heat must now be dissipated. Thereby saving construction space and weight. For example, the cooling ribs for the pre-charging resistor can be dimensioned smaller.

Drawings

Embodiments of the invention are explained in more detail below with reference to the figures. In which, schematically:

figure 1 shows a view of a vehicle,

figure 2 shows the on-board network of the vehicle in figure 1,

fig. 3 shows a charging curve of the capacitor of the on-board network in fig. 2.

List of reference numerals:

2 vehicle

4 vehicle network

6 drive train

8 electric memory

10 switch

12 capacitor

14 precharge circuit

16 ignition part

18 controller

20 data bus

22 door

24-door switch

26 inverter

28 electric machine

30 cell

32 contactor

34 pre-charging switch

36 precharge resistor

38 precharge branch

I current

Maximum current Imax

S Start event

U voltage

Ub vehicle network voltage

t-v precharge time.

Detailed Description

In fig. 1, a vehicle 2 is shown, which is an electric or hybrid vehicle. The vehicle 2 has an on-board network 4 with an electric drive train 6 and with an electric memory 8. The drive train 6 and the electrical storage 8 are part of the on-board network 4. The on-board network has a switch 10 for electrically disconnecting and connecting the electrical storage 8 and the drive train 6. The on-board system 4 has a capacitor 12, which can be precharged, for protecting the drive train 6 when connected to the electrical storage device 8. In order to precharge the capacitor 12 in the precharge mode, the vehicle electrical system 4 has a precharge line 14. The on-board system 4 is currently a high-voltage on-board system and has an operating voltage of 400V. An extremely simplified equivalent circuit diagram of the on-board network 4 is shown in fig. 2. The connections for the signaling technology for the control are shown in dashed lines in fig. 1 and 2, while the electrical connections for the transmission of power are shown in continuous lines.

Within the scope of the method for operating the vehicle 2, the precharging operation is activated in a start event S, which is triggered by a user when the vehicle 2 is started and before the ignition 16 of the vehicle 2 is actuated. Only when the capacitor 12 has been precharged, the switch 10 is switched and the electrical storage 8 is electrically connected with the drive train 6 to drive the vehicle 2. To carry out the method and to activate the precharging operation, the vehicle 2 has a controller 18, which is currently a battery management module and is integrated into the electrical memory 8. The controller 18 is coupled to a data bus 20 for exchanging control signals with other components or controllers.

A large number of events are in principle conceivable and suitable as starting events S. In the illustrated embodiment, the start event S is the opening of a door 22, which is the driver door of the vehicle 2. The opening is recognized by means of the door switch 24. The gate switch is connected to the controller 18 in terms of signals, so that it reacts to the opening of the gate 22 and then activates the precharge operation. The opening of the door 22 takes place in each case at certain time intervals before the actuation of the ignition 16. The precharge time t-v is thus significantly extended and is typically several seconds. The door switch 24 is currently also used for the control of other tasks, for example for activating interior space lighting, not shown.

In a variant not shown, the start event S is the unlocking of the vehicle 2. This unlocking is typically effected by the user and, for example, by means of a key or a remote control or automatically, for example, when the user approaches the vehicle 2. In a further variant, the start event S is already the corresponding approach of the user to the vehicle 2.

In order to still precharge the capacitor 12 in the absence of a start event S, the precharge operation is currently activated when the ignition 16 is actuated, provided that it has not been activated before. This is achieved by virtue of the fact that, when the ignition 16 is actuated, a corresponding signal is sent to the controller 18 and it is then checked whether the precharging operation has been activated and, if this is not the case, the precharging operation is activated. The ignition 16 is correspondingly connected to the control unit 18 in terms of signal technology.

In the exemplary embodiment shown, the capacitor 12 is integrated into an inverter 26, which is designed to convert the direct voltage of the electrical energy store 8 into an alternating voltage for the electric machine 8 of the drive train 6. As can be seen in fig. 2, the capacitor 12 forms the input capacitance of the inverter 26. The capacitor 12 serves primarily as a balancing element or energy buffer in order to improve the conversion of the direct voltage into an alternating voltage and to decouple the electrical storage device 8 from the harmonic oscillations of the inverter 26 caused by operation. The capacitor 12 is also referred to as a power capacitor.

The electrical storage 8 has two interfaces 28 via which electrical energy can be drawn from the electrical storage 8. In this case, the interface 28 is connected to a plurality of batteries 30 of the electrical storage device 8. The switch 10 for disconnecting and connecting the electrical storage 8 and the drive train 6 is currently integrated into the electrical storage 8 and is designed as a power switch and has two contactors 32 (one in each case for one of the interfaces 28) in order to disconnect it from the remaining on-board system 4 or to connect it to the remaining on-board system 4. But a design with two contactors 32 is not mandatory. The switch 10 is connected to and also switched by the controller 18.

Various designs are suitable for the precharge circuit 14. Fig. 2 shows a variant in which the precharging circuit 14 has a precharging switch 34 and a precharging resistor 36, which are connected in series with one another in a precharging branch 38. The pre-charging branch 38 is in turn connected in parallel to the switch 10, in particular to one of the contactors 32. When the precharge operation is activated, precharge switch 34 is closed and switch 10 is bypassed, so that capacitor 12 is charged via precharge resistor 36. In a variant not shown, the precharging circuit 14 likewise has a precharging branch 38, but rather a dc voltage converter which is activated in the precharging mode and has a precharging resistor via which the capacitor 12 is charged in a manner similar to the variant of fig. 2.

Since the precharging operation is currently activated significantly earlier due to the specially selected starting event S than in response to an actuation of the ignition 16, until the actual driving has started, a correspondingly longer precharging time t-v is available. An exemplary charging curve for capacitor 12 is shown in fig. 3. In which the voltage U at the capacitor 12 and the precharge current for the capacitor 12 are shown as a function of time t in a common diagram. Also shown is a pre-charge time t-v that illustrates after what time the initially uncharged capacitor 12 is charged to 90% of its total charge. Fig. 3 also shows the operating voltage Ub and the maximum current Imax during the precharging by means of a dotted, horizontal line. In the precharge mode, the capacitor 12 is currently precharged for a precharge time t-v, which is longer than 1s and is here roughly 2s in fig. 3. The extended precharge time t-v enables a reduction of electrical requirements and thus a more flexible design of the various components, in particular the precharge circuit 14. In the precharge mode, therefore, the capacitor 12 is currently precharged with a particularly low maximum current Imax of 1A. This is currently achieved by the pre-charge resistor 36 having a resistance value of at least 100 Ohm.