DE102018220780A1 - Method for operating an at least partially electrically powered vehicle - Google Patents

Abstract

A method for operating an electrically driven vehicle with at least one electrical energy storage unit and a power electronic component is described, comprising the steps of: a) determining a destination and / or a category of a desired journey with the electrically driven vehicle; b) determining at least one current limit value for an electric current used in the vehicle for the electric drive depending on the destination and / or the category of the intended journey in step a); c) controlling the power electronic component in such a way that the current limit value from step b) is maintained Device, a corresponding computer program, a corresponding machine-readable storage medium with the computer program and an electrical energy store with the device.

Description

The present disclosure is based on a method for operating an at least partially electrically powered vehicle.

State of the art

Due to the increasing electrification, particularly in the vehicle sector, electrical energy storage devices are becoming increasingly important and in greater demand. In addition to increasing energy and power density, the focus is also on at least local savings of climate-damaging substances, in particular climate-damaging gases such as carbon dioxide. Electrical energy storage devices are usually made up of several smaller electrical energy storage units, which are electrically connected to one another in a suitable manner. In particular, optimization or suitable operation of these electrical energy storage units, for example when it comes to compliance with certain current limits in the vehicle, is important here. On the one hand, compliance with this limit value can be safety-critical, on the other hand, additional functionalities can be mapped via it, for example an increased service life of the electrical energy storage units.

Particularly in the case of electrically powered vehicles such as hybrid vehicles, that is to say vehicles which, in addition to an electric motor, also have an internal combustion engine, a corresponding specification of current limit values for the best possible exploitation of the CO2 saving potential makes sense. This applies, for example, to systems with 48V-based electrical energy storage systems.

Disclosure of the invention

Advantages of the invention

A method for operating an electrically driven vehicle, a corresponding device, a corresponding computer program and a corresponding electrical energy store with the features of the independent claims are disclosed.

Within the scope of the method, a destination and / or a category of a desired journey with the electrically driven vehicle is determined, so that a length of the desired journey is known or can simply be determined by means of the current location of the vehicle and the destination, or at least the type the intended journey, for example within a city or a longer overland journey, is known.

Furthermore, at least one current limit value is determined for an electrical current used in the vehicle for the electrical drive, which flows into or out of the electrical energy storage unit, the determination taking place as a function of the destination and / or the category of the intended journey. For example, a higher current limit value can be determined for a journey in the city center than for a long overland journey at higher speed, during which, for example, an internal combustion engine can be operated efficiently in a hybrid vehicle.

Furthermore, a power electronic component, for example an inverter, is controlled in such a way that the at least one current limit value is maintained.

This is advantageous because the electrical energy storage unit is deliberately used in the best possible way in order to at least locally save carbon dioxide through the use of the energy stored in it, since the vehicle is driven as well as possible with electrical energy from the electrical energy storage within the current limit value. For example, the vehicle is operated with a higher current limit for shorter distances since the vehicle will not be in operation after the shorter use. This enables, for example, cooling of the electrical energy storage unit or internal compensation of possible potential differences in electrodes of the electrical energy storage. Such cooling is not possible with longer use, for example when driving overland, so a lower current limit value is specified there, for example. The speed at which a corresponding temperature limit value is reached can thus also be influenced, for example, by correspondingly specifying the current limit value. This is particularly advantageous for electrical energy storage units that do not have a thermal management system or are not actively cooled. Compliance with temperature limits is very challenging there. This applies, for example, to 48V-based electrical energy storage devices.

Further advantageous embodiments of the present invention are the subject of the dependent claims.

A saving of a climate-damaging substance is expediently determined, which is achieved as a function of the determined current limit value. Furthermore, the saving of the climate-damaging substance is displayed in order to enable a user of the vehicle to evaluate and / or change his driving behavior. This is advantageous because a user is made to do so consciously and with the lowest possible emissions drive, for example by preventing extreme braking maneuvers or acceleration processes that cause the current limit value to be exceeded.

At least one control parameter of a thermal management system is expediently set as a function of the determined current limit value. This is advantageous since, on the one hand, a higher control quality, for example a faster settling time or lower overshoot, is achieved and, on the other hand, reduced expenditure for the manipulated variable, for example reduced electrical currents in a pump drive of the thermal management system, is also necessary. This contributes to the saving on the climate-damaging substance and also has a positive effect on the service life of the electrical energy storage unit due to the better control quality. A control parameter is, for example, the value of the constant of a proportional controller.

The saving is expediently determined by means of a mathematical model in which at least one value of electrical energy is represented with a value of the climate-damaging substance. This is advantageous because, depending on the situation or after a trip, a saving in the climate-damaging substance can be specified directly.

A thermal management system is expediently controlled in such a way that a predefined temperature limit value for the electrical energy storage unit is not exceeded. This is advantageous because it prevents excessive heating of the electrical energy storage unit, which on the one hand increases its service life and on the other hand ensures its performance.

The current limit value is expediently based on an effective value of the current. This is advantageous since the effective value is a suitable measure for the thermal output dropping at an ohmic consumer. When determining whether the current limit value is observed, the effective value of the current is thus determined from measured current values and compared with the current limit value given as the effective value.

The disclosure furthermore relates to a device for operating an electrically driven vehicle, the vehicle having at least one electrical energy storage unit and a power electronic component. Furthermore, the device comprises at least one means, which is designed in particular as a battery management control device, the at least one means being set up to carry out the steps of the disclosed method. Thus, the advantages mentioned above can be realized by the device.

The disclosure furthermore relates to a computer program which is set up to carry out all steps of the disclosed method. Thus, the advantages mentioned above can be realized by the computer program.

The disclosure furthermore relates to a machine-readable storage medium on which the disclosed computer program is stored. In addition to the advantages already mentioned, this results in the advantage of simple and quick distribution of the computer program by means of the storage medium.

The disclosure furthermore relates to an electrical energy store which has at least one electrical energy storage unit and a disclosed device. If the electrical energy storage device is installed in an electrically driven vehicle, the advantages mentioned above can be realized.

An electrical energy storage unit can in particular be understood to mean an electrochemical battery cell and / or a battery module with at least one electrochemical battery cell and / or a battery pack with at least one battery module. For example, the electrical energy storage unit can be a lithium-based battery cell or a lithium-based battery module or a lithium-based battery pack. In particular, the electrical energy storage unit can be a lithium-ion battery cell or a lithium-ion battery module or a lithium-ion battery pack. Furthermore, the battery cell can be of the type lithium polymer accumulator, nickel metal hydride accumulator, lead acid accumulator, lithium air accumulator or lithium sulfur accumulator or very generally an accumulator of any electrochemical composition. A capacitor is also possible as an electrical energy storage unit.

The at least one means can comprise, for example, a battery management control device and corresponding power electronics, for example an inverter, and current sensors and / or voltage sensors and / or temperature sensors. An electronic control unit, in particular in the form of a battery management control device, can also be such a means.

An electronic control unit can be understood to mean, in particular, an electronic control device which, for example, comprises a microcontroller and / or an application-specific hardware module, for example an ASIC, but it can also include a personal computer or a programmable logic controller.

Figure list

Advantageous embodiments of the invention are shown in the figures and detailed in the following description.

• 1 ein Flussdiagramm des offenbarten Verfahrens gemäß einer ersten Ausführungsform;
• 2 ein Flussdiagramm des offenbarten Verfahrens gemäß einer zweiten Ausführungsform;
• 3 ein Flussdiagramm des offenbarten Verfahrens gemäß einer dritten Ausführungsform;
• 4 Diagramme, die schematisch die Auswirkungen des offenbarten Verfahrens gemäß einer Ausführungsform visualisieren; und
• 5 eine schematische Darstellung der offenbarten Vorrichtung gemäß einer Ausführungsform.

Show it:

• 1 a flowchart of the disclosed method according to a first embodiment;
• 2nd a flowchart of the disclosed method according to a second embodiment;
• 3rd a flowchart of the disclosed method according to a third embodiment;
• 4th Diagrams that schematically visualize the effects of the disclosed method according to one embodiment; and
• 5 is a schematic representation of the disclosed device according to an embodiment.

Embodiments of the invention

The same reference symbols in all figures denote the same device components or the same method steps.

1 shows a flow diagram of the disclosed method according to a first embodiment. The method is used to operate an electrically powered vehicle with at least one electrical energy storage unit and a power electronic component. In a first step S11 determined a destination. Alternatively and / or additionally, in the first step S11 the category of a desired journey can be determined by a user of the vehicle selecting it, for example on a screen, for example inner-city journey or overland journey.

In a second step S12 at least one current limit value is determined for an electrical current used in the vehicle for the electrical drive, the current limit value being determined as a function of the destination. Alternatively and / or additionally, the determination can be made depending on the category of the intended journey. For example, the current limit value for an inner-city drive can be higher than for an overland drive, since expressways are typically also used for expressways, which leads to permanent heating of the electrical energy storage unit. The higher limit for inner-city driving is due to the fact that the vehicle is used for a shorter period and is not in operation afterwards. The electrical energy store can thus cool down.

In a third step S13 a power electronic component is controlled in such a way that the current limit value is maintained when the vehicle is used. The power electronic component is designed in particular as an inverter.

2nd shows a flow diagram of the disclosed method according to a second embodiment. The method for operating an electrically driven vehicle with at least one electrical energy storage unit and a power electronic component is used. In a first step S21 determined a destination. This is done via an input on a screen or via a voice command. Alternatively and / or additionally, in the first step S21 the category of a desired trip can be determined.

In a second step S22 at least one current limit value is determined for an electrical current used in the vehicle for the electrical drive, the current limit value being determined as a function of the destination. Alternatively and / or additionally, the determination can be made depending on the category of the intended journey.

In a third step S23 a power electronic component is controlled in such a way that the current limit value is maintained. The power electronic component can be designed as an inverter.

In a fourth step S24 After the end of the trip, a saving of a climate-damaging substance is determined depending on the current limit value. This climate-damaging substance can in particular include carbon dioxide. This is done by evaluating the flow of current. A multiplication of the current by a corresponding system voltage and an integration over a corresponding period of time results in a corresponding amount of energy that was saved by the electric drive. This saved amount of energy is converted into a corresponding saved amount of the climate-damaging substance using a mathematical model in which at least one value of electrical energy is linked to a value of the climate-damaging substance.

In a fifth step S25 the amount of the climate-damaging substance saved is displayed to a user, for example on a screen, in order to enable the user of the vehicle to evaluate and / or change his driving behavior.

3rd shows a flow diagram of the disclosed method according to a third embodiment. The method is used to operate an electrically powered vehicle with at least one electrical energy storage unit and a power electronic component. In a first step S31 determined a destination. Alternatively and / or additionally, in the first step S31 the category of a desired journey can be determined by a user of the vehicle selecting it, for example on a screen, for example inner-city journey or overland journey.

In a second step S32 at least one current limit value is determined for an electrical current used in the vehicle for the electrical drive, the current limit value being determined as a function of the destination. Alternatively and / or additionally, the determination can be made depending on the category of the intended journey.

In a third step S33 at least one control parameter of a thermal management system is set, the control parameter being set as a function of the determined current limit value. This is done by setting a corresponding value for the control parameter in a memory, for example in an electrical control unit.

In a fourth step S34 a thermal management system is controlled such that a predefined temperature limit for the electrical energy storage unit is not exceeded. This is done by means of a corresponding activation of the thermal management system, for example by activation of a pump or a blower.

In a fifth step S35 the power electronic component is controlled in such a way that the current limit value is maintained. This is controlled by an electronic control unit.

4th shows diagrams that schematically visualize the effects of the disclosed method according to the second embodiment when the at least one current limit value is based on an effective value of the current and the vehicle is in particular a hybrid vehicle that has, for example, an electrical energy store in the form of a battery with a voltage level of 48 V. The battery can at least support the drive of the vehicle, which means that an internal combustion engine uses less fuel, for example. In the first diagram from above is the time course of the effective value I _rms of an electric current flowing in the vehicle for driving. Until a first point in time t ₁ is a first current limit I _{limit, 1} specified, which is provided here for an overland trip. This is lower than the second current limit value provided for an inner-city drive I _{limit, 2nd} , since the internal combustion engine can be operated efficiently when driving overland at high vehicle speeds and the CO2 saving potential is rather low. In addition, depending on the size of the electrical energy store, permanent electrical drive support cannot take place due to capacity restrictions. In order not to increase the temperature of the electrical energy storage unit too strongly during the overland journey, the first current limit value for the overland journey is deliberately chosen conservatively. The second current limit for city driving I _{limit, 2nd} applies from the first point in time t ₁ until a second point in time t ₂ . From the second point in time t ₂ until a third point in time t ₃ at which the journey is ended, the first current limit value applies again I _{limit, 1} , because the inner-city zone was left and, for example, another overland trip was made. The entire trip thus consists of a first overland trip, a city trip and a second overland trip.

In the second diagram from the top is the temperature over time T of the at least one electrical energy storage unit. It can be seen how higher electrical currents with a certain time lag on the temperature T affect the electrical energy storage unit and increase it.

The third diagram from above shows the amount of carbon dioxide saved by driving. Depending on the current level, the savings are stronger or weaker. The saving in carbon dioxide therefore depends on the applicable current limit. At the end of the trip at the third point in time t ₃ the amount of carbon dioxide saved is known or has been determined and can be communicated to the user of the vehicle. Furthermore, the specification of the current limit values ensured that the electrical energy store did not have an excessively high temperature, an excessively high temperature promoting faster aging or possibly even being safety-critical.

5 shows a schematic representation of the disclosed device 50 according to one embodiment. Via a screen 51 a user input takes place, which is sent to an electronic control unit 52 is passed on. The electronic control unit 52 controls the power electronic component 53 such that a current limit value determined within the disclosed method is maintained.

Claims (10)

Method for operating an at least partially electrically powered vehicle with at least one electrical energy storage unit and one power electronic component (53), comprising the steps: a) determining a destination and / or a category of a desired journey with the electrically driven vehicle; b) determining at least one current limit value for an electrical current used in the vehicle for the electrical drive as a function of the destination and / or the category of the intended journey in step a); c) triggering the power electronic component (53) in such a way that the current limit value from step b) is maintained. Procedure according to Claim 1 , further comprising: d) determining a saving of a climate-damaging substance, in particular carbon dioxide, as a function of the current limit value determined in step b); e) Indicating the saving of the climate-damaging substance in order to enable a user of the vehicle to evaluate and / or change his driving behavior. A method according to any one of the preceding claims, further comprising: f) setting at least one control parameter, in particular a controlled variable, of a thermal management system as a function of the current limit value determined in step b); Procedure according to Claim 2 , the determination being carried out using a mathematical model in which at least one value of electrical energy is represented with a value of the climate-damaging substance. A method according to any one of the preceding claims, further comprising: g) triggering a thermal management system such that a predefined temperature limit value for the electrical energy storage unit is not exceeded. Method according to one of the preceding claims, wherein the current limit value is based on an effective value of the current. Device (50) for operating an electrically powered vehicle, the vehicle comprising at least one electrical energy storage unit and a power electronic component (53), the device (50) comprising at least one means, in particular a battery management control unit, which is set up to perform the step of the method after one of the Claims 1 to 6 to execute. Computer program, which is set up all steps of the method according to one of the Claims 1 to 6 to execute. Machine-readable storage medium on which the computer program is based Claim 7 is saved. Electrical energy storage device, comprising at least one electrical energy storage unit and a device (50) according to Claim 7 .

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