Method and control device for charging energy store of motor vehicle

Abstract

The invention relates to a method for charging an energy store (14) of a motor vehicle (10) from an initial state of charge (Z1) of the energy store (14) to a final state of charge (Z2) of the energy store (14) at a vehicle-external power source (26), a control device (12) controlling the charging according to a first charging mode (L1), in this way, the energy store (14) is charged by the external energy source with the first power (P1) and according to the first overall efficiency ([eta] 1). The control device (12) determines whether an activation request (54) for activating a second charging mode (L2) representing the energy-saving mode (L2), which is proposed by the user (36), has been received, and at least if the activation request has been received, the control device (12) controls the charging process in accordance with the second charging mode (L2) in such a way that the energy store (14) is charged in accordance with a second overall efficiency ([eta] 2), the second overall efficiency is higher than the first overall efficiency ([eta] 1) and lower than the possible highest overall efficiency ([eta] max).

Description

Technical Field

[0001] The invention relates to a method for charging an energy accumulator of a motor vehicle from a determined initial state of charge of the energy accumulator to a determined final state of charge of the energy accumulator at an electrical energy source external to the vehicle, wherein, when a first charging mode is set, a control device controls the charging according to the first charging mode in such a way that the energy accumulator is charged from the initial state of charge to the final state of charge by the external energy source at a first charging power and according to a first overall efficiency, the first overall efficiency being the ratio of a first energy stored in the energy accumulator to a second energy taken from the energy source when charging from the initial state of charge to the final state of charge. The invention also relates to a control device for a motor vehicle. Background Art

[0002] It is known from the prior art that electric vehicles can undergo a fast charging process. This is understood as a charging process performed at a very high charging power. Accordingly, this fast charging process can be completed in a very short time. Here, the fast charging is usually conceived in a motor vehicle in such a way that it is charged at the fastest possible speed during fast charging. Therefore, the vehicle requires the charging pile to provide the maximum charging current possible from a technical point of view. However, the high charging power also leads to higher energy losses during charging, which must also be paid by the user. Accordingly, it is also known from the prior art that the user can preset a certain charging priority, for example, charging in a cost-effective manner.

[0003] For example, DE 10 2017 116 418 A1 describes a system comprising: an electric vehicle having a battery pack; a human-machine interface designed to receive input for setting a charging profile; and a control device. In addition, the system comprises a battery system that selectively charges the battery pack in response to an instruction of the control device. In addition, the control device is designed to instruct the battery system to charge the battery pack in a manner consistent with the charging profile. Here, the input for setting the charging profile may include selecting at least one battery cell corresponding to a desired charging time and a desired electricity cost.

[0004] Furthermore, US 9,853,488 B2 describes a charging system having vehicle sensors, a communication device and a processor, which determines a charging process for charging the vehicle according to charging preferences specified by a user of the vehicle and performs charging accordingly. By means of the charging preferences, it can be specified that the vehicle should be charged to a certain percentage of its total capacity before a certain time, or that the vehicle should be charged to a certain level that enables a certain distance to be traveled.

[0005] In principle, it is feasible for the user to specify various presets or preset priorities related to the charging process. However, this makes each charging process very troublesome, time-consuming and complicated for the user. Summary of the invention

[0006] It is therefore an object of the present invention to provide a method and a control device which allow the most efficient possible charging of an energy store / electric accumulator and in doing so ensure the greatest possible operating and charging comfort.

[0007] This object is achieved by a method and a control device having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject matter of the dependent claims, the description and the drawings.

[0008] In a method according to the invention for charging an energy storage device of a motor vehicle from a determined initial state of charge of the energy storage device to a determined final state of charge of the energy storage device at an electrical energy source external to the vehicle, when a first charging mode is set, a control device controls the charging according to the first charging mode such that the energy storage device is charged from the initial state of charge to the final state of charge by the energy source external to the vehicle at a determined first power according to a first overall efficiency, the first overall efficiency being the ratio of a first energy stored in the energy storage device to the energy taken from the energy source when charging from the initial state of charge to the final state of charge. Furthermore, the control device checks whether an activation request has been received from a user for activating a second charging mode representing an energy-saving mode, and, under a first precondition that the control device has determined that the activation request has been received, the control device activates the second charging mode and controls the charging process according to the second charging mode such that the energy storage device is charged from the initial state of charge to the final state of charge by the energy source external to the vehicle according to a second overall efficiency, the second overall efficiency being higher than the first overall efficiency and lower than a determined maximum overall efficiency.

[0009] Here, the present invention is based on a number of insights: In the early days of the development of electric vehicles, the charging power and driving range of electric vehicles were relatively small. Therefore, the idea of ​​the fast charging process is to charge at the maximum possible charging power in order to minimize the charging duration. However, significantly higher charging powers and greater driving ranges are now achievable, and the charging power and driving range have been further improved in recent years. Now, for the charging process from 10% capacity or state of charge to 80% state of charge, the charging time has reached a range of less than 25 minutes. However, this very high charging power leads to increased energy loss during charging. It is precisely within the scope of the already achievable very short charging time that it is no longer necessary to complete the charging process with the fastest possible power, because, for example, sometimes charging pauses, such as due to coffee breaks, toilet breaks, travel time, etc., may always take longer, such as 30 minutes, especially because the distance that can be driven after charging is also increased. Thus, in many cases, a slightly longer charging time does not affect the user's comfort, but on the other hand, by slightly extending the charging time, in particular by slightly reducing the charging power, the power loss can already be reduced overall, and thus energy losses and money can be saved during charging. Especially when charging with very high charging powers, in particular DC (direct current) charging, the energy losses increase due to the internal cell resistance of the energy storage device, and due to the thermal management of cooling the energy storage device during the charging process, and also due to a certain, but smaller, power loss due to the onboard power supply. Now, the present invention uses the following knowledge, in order to set the Eco mode, i.e. the second charging mode, in which the charging time does not need to be significantly or significantly increased overall, according to which the energy storage device can be charged more efficiently, that is to say with higher efficiency. In other words, according to this second charging mode, charging should not be carried out at the highest possible efficiency, because this could lead to a significant extension of the charging time, but should be carried out in a predetermined, moderately efficient manner, so that on the one hand the power loss can be reduced, and on the other hand the charging time is only slightly extended overall. Accordingly, the extension of the charging time does not lead to a significant reduction in user comfort, and energy can be saved at the same time. For example, in order to activate such an Eco charging mode, it is sufficient for the user to actuate a corresponding operating element to issue an activation request. Therefore, the user does not have to make complex presettings in terms of the charging configuration. In the simplest case, an Eco button can be provided in the vehicle, for example, and the user presses the Eco button before or during the charging process to activate the Eco charging mode. Thus, the present invention achieves a combination of very high user operating comfort and charging comfort with an increase in charging efficiency.

[0010] For example, the energy storage device can be a battery of a motor vehicle, in particular a high-voltage battery. The vehicle-external power source can be a charging station or a charging post or a wall box or the like. Furthermore, the energy source external to the vehicle can be a public charging facility or a private charging facility. Within the scope of the invention, the charging of the energy storage device is preferably carried out as direct current charging, that is to say DC charging. Especially when DC charging, very high charging powers can be provided, and especially when the possible maximum charging power is very high, the second charging mode is very effective.

[0011] Here, the charging time when charging starts from the initial state of charge of the energy accumulator does not necessarily have to be the starting time of the charging process itself, but this is nevertheless feasible. In other words, the second charging mode can also be activated during a charging process that has already been carried out. Subsequently, the state of charge of the energy accumulator corresponds to the initial state of charge of the energy accumulator at this activation time. Here, the state of charge of the energy accumulator, that is to say the initial state of charge and the final state of charge, can be percentage data relative to the total capacity of the energy accumulator. The state of charge is often also referred to as SOC (State of Charge) and is given as a percentage. The final state of charge can also be preset by the user. If the user does not specify the final state of charge in detail, the final state of charge can also be preset by the control device. The user can convey an activation request for activating the second charging mode via the operating element of the control device, as explained in more detail later. Therefore, the activation request can be provided in the form of a corresponding activation signal and received by the control device. Furthermore, such operating elements, in particular real and / or virtual operating elements, may also be provided by the motor vehicle itself, for example in the form of operating menus or operating displays on a touch screen, or may also be provided by the user's mobile communication device or by an App running on such a mobile communication device.

[0012] Here, the first charging power for charging according to the first operating state may be a possible maximum charging power. The possible maximum charging power is the charging power that can be achieved from a technical point of view by the external energy source and the motor vehicle. In other words, the maximum charging power is the lower of the two charging powers that can be achieved by the external energy source on the one hand and by the vehicle on the other hand.

[0013] The charging power, i.e. the first charging power and the second charging power mentioned later, should also be understood as a charging power value, that is, a value of the charging power. The second charging power mentioned later is less than the first charging power or is reduced relative to the first charging power, which can be understood accordingly as that the charging power value of the first charging power is less than the charging power value of the second charging power. In addition, the term "first charging power or second charging power" can be understood as at least one first charging power or second charging power. In the course of the charging process from the initial state to the final state, the first charging power or the second charging power can change. That is, during the charging process, the charging power does not usually have to be constant. Here, the first charging power can be, for example: a first maximum charging power value achieved during the charging process; a first charging power curve, which includes a plurality of, in particular different, time-sequential first charging power values, in particular including all time-sequential power values ​​when charging from the initial state of charge to the final state of charge; and / or an average first charging power, for example as an average value of the first charging power curve. This also applies to the second charging power as explained in more detail later. The first charging power or the second charging power can also be understood as a charging power curve of the first charging power or the second charging power over time, that is, a first charging power curve or a second charging power curve.

[0014] According to the example, a charging process according to the second charging mode, in which charging is performed at an efficiency higher than the first overall efficiency but at an overall efficiency lower than the determined possible maximum efficiency, can be realized in a simple manner by reducing the possible maximum charging power, that is, reducing the first charging power, but not minimizing it, i.e. not setting it to the minimum charging power value possible for the charging process. Thus, an unjustified limitation to an extremely low charging power can be avoided.

[0015] The total efficiency, i.e. the first total efficiency, the second total efficiency and the possible maximum total efficiency, should also be understood as efficiency values ​​of the efficiency, that is to say the value of the total efficiency. Here, the total efficiency is generally understood to be the efficiency defined in general. Here, both the first total efficiency and the second total efficiency indicate the ratio between the first energy charged into the energy storage device from a certain initial state to a certain final state during the charging process and the second energy obtained from the external energy source. The difference between these two energies lies in the energy losses that may be caused by the components described above. Therefore, the second total efficiency is higher than the first total efficiency, which means that the energy losses are reduced in the (same) charging process according to the second charging mode compared to the otherwise identical charging process in the first charging mode.

[0016] Preferably, the control device can be a vehicle-internal control device, that is to say, the control device is part of the motor vehicle. However, the control device can also be a vehicle-external control device which can communicate with the motor vehicle via a communication connection.

[0017] In another very advantageous embodiment of the invention, the second charging mode is activated, in particular effectively activated, only under a second precondition, i.e., the maximum possible charging power for charging, which is in particular equal to the first charging power, is greater than a predetermined threshold value. The predetermined threshold value can usually be within a limited power interval having a lower limit and an upper limit.

[0018] The lower limit of the restricted power range may be, for example, between 30 kW (inclusive) and 100 kW, or between 40 kW and 80 kW, or between 40 kW (inclusive) and 60 kW, or between 45 kW (inclusive) and 55 kW.

[0019] The upper limit of the limited power range, which is greater than the lower limit, may be, for example, between 70 kW (inclusive) and 250 kW, or for example, between 80 kW and 200 kW, or for example, between 80 kW (inclusive) and 150 kW, or for example, between 85 kW (inclusive) and 120 kW, or for example, between 90 kW (inclusive) and 120 kW, or for example, between 90 kW (inclusive) and 110 kW.

[0020] The predetermined threshold value can typically be within a restricted power range of 40 kW (inclusive) to 250 kW, or within a restricted power range of 40 kW (inclusive) to 220 kW, or within a restricted power range of 40 kW (inclusive) to 200 kW, or within a restricted power range of 40 kW (inclusive) to 150 kW, or within a restricted power range of 40 kW (inclusive) to 120 kW, or for example within a restricted power closed range of 40 kW to 100 kW, or for example within a restricted power range of 40 kW (inclusive) to 80 kW, for example, 50 kW.

[0021] This is particularly advantageous, since the advantages of the second charging mode are particularly evident precisely at very high charging powers. At low charging powers anyway, no significant energy savings can be achieved, so that at best the charging time is unnecessarily prolonged. This can be advantageously avoided. However, precisely at very high charging powers, a slight reduction in the charging power leads only to a very small extension of the charging time, for example in the range of a few minutes, while at the same time a considerable amount of energy loss can be saved.

[0022] In the case where the possible maximum charging power is less than a predetermined threshold value, it can be provided according to a less preferred embodiment that the user is not provided with the possibility of expressing an activation request at all. For example, an operating element assigned to the energy-saving mode and displayed on a touch screen, that is to say a touch screen, cannot be operated, that is, when operated, for example touched, by a user, no function is triggered or at least no function of sending an activation request to the control device is triggered, and it is displayed, for example, in gray or not even displayed. When an operating element that cannot actually be operated is operated, for example, information can be output to the user that the energy-saving mode is currently not activatable or not usable.

[0023] However, the user is preferably always provided with the possibility of expressing an activation request by operating the operating element, and for example also displays to the user that the second charging mode is already activated, wherein activation of the second charging mode only takes effect starting from the above-mentioned threshold value, or preferably the activated second charging mode only takes effect. That is, the second charging mode can also be activated when the maximum possible charging power is below the threshold value, but the second charging mode only takes effect starting from this threshold value.

[0024] For example, the user can activate the second charging mode by means of an operating element, and then keep the activation until deactivation by another operation of the user. However, although the second charging mode is activated or effective, it does not have to be effective in every charging process, but only when the maximum charging power possible in such a charging process reaches or exceeds a threshold value.

[0025] In another advantageous embodiment of the present invention, when the second charging mode has been activated, the control device controls the charging process according to the second charging mode in such a way that the energy storage device is charged from an initial state of charge to a final state of charge by an external energy source at a second charging power that is reduced relative to the first power, and in particular, before the charging process according to the second charging mode starts, the control device predicts an estimated charging time based on the second charging power and outputs it to the user via an output device.

[0026] As already mentioned, the start of the charging process according to the second charging mode does not necessarily have to coincide with the start of the entire charging process. For example, a charging process can also first be carried out according to the first charging mode, for example from an initial, second initial state of charge to the first initial state of charge, and then, if the user activates the second charging mode during this period, the control device can switch to a charging strategy according to the second charging mode and accordingly continue the charging process from the first initial state of charge to the final state of charge according to the second charging mode.

[0027] In this case, the reduction of the second charging power relative to the first charging power can be understood as the time average value, starting value or maximum value of the charging power curve of the second charging power over time being smaller than the corresponding average value, starting value or maximum value of the charging power curve of the first charging power over time, or, for example, for all power values ​​corresponding to the same state of charge value of the energy storage device, the entire second charging power curve is smaller than the first charging power curve.

[0028] By reducing the charging power, the power loss can be reduced in a simple manner. Preferably, the charging power is reduced in such a way that the charging time is not significantly prolonged, for example by a maximum of 15 minutes or a maximum of 10 minutes. The reduction in charging power from the first charging power to the second charging power can be limited, for example, to a maximum of 30% of the first charging power, preferably less.

[0029] It is also very advantageous to display the "new" estimated charging time according to the second charging mode to the user. Based on this "new" estimated charging time, the user can better decide whether he is willing to accept the extended charging time that helps save energy, or whether he has time to charge anyway.

[0030] Here, the output device can be an output device of the motor vehicle and / or an output device of the user's mobile communication device. For example, the charging time can also be transmitted to an external energy source, such as a charging station, which itself provides a corresponding display.

[0031] In another very advantageous embodiment of the invention, the maximum possible charging power for charging, in particular corresponding to the first charging power, is reduced in a predetermined manner according to the second charging mode, in particular by multiplying the maximum possible charging power by an efficiency factor. Preferably, the efficiency factor is greater than zero and less than one. By multiplying the maximum possible charging power by such a factor, the charging power can be reduced or a new first charging power can be determined in a particularly simple manner in terms of calculation. In this case, it is particularly preferred that the efficiency factor is greater than 0.5, in particular greater than 0.6, or at least 0.7. As a result, it is possible to achieve only a slight reduction in the charging power in the energy-saving mode.

[0032] In a particularly simple design, the efficiency factor is fixedly preset, that is to say independently of the possible maximum charging power, in particular only a single efficiency factor is preset. In another very advantageous design of the present invention, an assignment relationship / correspondence is stored in the memory of the control device, which assigns a plurality of different power ranges for the possible maximum charging power to corresponding efficiency factors from a plurality of different efficiency factors, wherein the control device selects the efficiency factor according to the possible maximum charging power according to the assignment relationship. It is also very advantageous here to design the assignment relationship in such a way that the smaller the associated possible maximum charging power, the greater the efficiency factor. For example, the efficiency factor for a charging power in the range of 0 to 99 kilowatts can be 1. That is to say, the second charging mode is fully effective only from a possible maximum charging power of 100 kilowatts, because before this the possible maximum charging power is not reduced by the efficiency factor 1. For example, the second charging mode is always activatable, but it is only effective or effective from a charging power of, for example, 100 kW. For a charging power within a closed interval of 100 kW to 159 kW, the efficiency factor can be, for example, 0.9; for a charging power within a closed interval of 160 kW to 219 kW, the efficiency factor can be, for example, 0.8; and for a possible maximum charging power starting from, for example, 220 kW and above, the efficiency factor can be, for example, 0.7. In this case, the corresponding efficiency factor can also be preset as a fixed value and stored in the assignment relationship. As a result, the first charging power for charging according to the second charging mode can also be determined very simply in terms of calculation. In this case, preferably only a small number of different charging power ranges, that is to say charging power value intervals, for example less than 10, in particular less than 5, are defined in total.

[0033] According to another advantageous embodiment of the invention, a characteristic curve is stored in the memory of the control device, which characteristic curve links the parameters of the energy storage temperature, the maximum possible charging power and the efficiency factor, wherein the control device selects the efficiency factor according to the characteristic curve as a function of the maximum possible charging power and the current energy storage temperature of the energy storage. As a result, the temperature of the energy storage, which is referred to as the energy storage temperature, can also be advantageously taken into account. For example, this temperature is the current temperature of the energy storage, for example, the current temperature at the time of activation of the energy saving mode or at the time when the user expresses his activation request, for example by operating an operating element. Therefore, the characteristic curve can be constructed as the assignment relationship described above, wherein the temperature of the energy storage is also taken into account as an additional input parameter. With the help of the characteristic curve, the corresponding first charging power can be assigned to the value pairs of the energy storage temperature and the maximum possible charging power. For example, the first charging power can be designed according to the characteristic curve so that the energy loss caused when charging according to the newly designed first charging power is reduced by x%, for example, by 20%, compared to the energy loss generated when charging with the first charging power, that is, the maximum possible charging power. As a result, the first charging power can be determined particularly well in a manner adapted to the situation.

[0034] In another advantageous embodiment of the present invention, in order to activate the second charging mode by the user, a user input is received, which specifies an extension of the charging time compared to the shortest possible charging duration for the maximum possible charging power, and the control device determines a second charging power that is reduced relative to the first charging power based on the charging time extension, and controls the charging process in the second charging mode based on the determined second charging power.

[0035] Here, the first charging power corresponds to the maximum possible charging power. In other words, the first charging mode is designed such that charging is performed according to the maximum possible charging power. Therefore, with respect to the embodiment of the present invention, the maximum possible charging power described below is equivalent to the first charging power.

[0036] According to an advantageous design of the present invention, the user can, for example, select what kind of charging time extension he can tolerate. For example, the user can set it via a sliding regulator displayed on the screen, in particular a real or virtual sliding regulator. In this case, the user can move the charging time from the shortest possible charging time corresponding to the first charging power to the longest charging time he can tolerate. Therefore, a charging time extension is obtained from this, and the control device determines the corresponding second charging power based on this charging time extension, and then selects the second charging power accordingly so that when the charging process is carried out according to the second charging mode with the second charging power, the maximum tolerable charging time specified by the user through the charging time extension is not exceeded.

[0037] The charging time and the charging duration are to be understood as synonymous terms. The charging time is the time from the starting point in time, at which the energy is supplied to the energy storage device from the initial state of charge by an energy source external to the vehicle, during the charging process, to the final point in time, at which the final state of charge is reached. The user can select a charging time extension in the following way, i.e., the user selects a charging time that is extended relative to the shortest charging time, the extended charging time being the charging duration defined above, i.e., the total charging duration of the charging process from the initial state of charge to the final state of charge, or the user selects a time difference that specifies how long the charging process is extended relative to the shortest charging time.

[0038] For example, the user can make such a setting via an operating and display menu for charging control, for example via a charging selection menu. To this end, the operator, for example, operates a virtual charging selection operating element and then enters a charging selection menu with a displayed, for example virtual, sliding control for setting the maximum charging time extension that the user can tolerate. This also has the great advantage that the estimated charging duration, that is, the charging time, is simultaneously displayed to the user in this way.

[0039] According to another advantageous embodiment of the present invention, in order to activate the second charging mode by the user, the control device receives a user input which specifies a charging power which is reduced relative to the possible maximum charging power, wherein the control device then controls the charging process in the second charging mode according to the specified second charging power. That is, instead of presetting an extension of the charging time, the user can also directly set a reduction in the charging power via a corresponding menu. Similar to the setting of the charging time, this can be done via a virtual sliding regulator. As a result, the user can directly preset the maximum second charging power to be used according to the second charging mode.

[0040] In this case, the charging power specified by the user should be understood as a single charging power value, especially the charging power value of the second charging power. The charging power value can be the time average value or the starting value or the maximum value of the time variation curve of the second charging power, preferably the maximum value or the time average value.

[0041] In another advantageous embodiment of the invention, the control device provides a display on the display device, according to which different charging powers that are reduced relative to the possible maximum charging power can be displayed to the user, for example in a chronological order, wherein the assigned estimated charging duration is displayed for each currently displayed charging power. This is particularly advantageously combined with the above-described embodiment, according to which the user is provided with the possibility of presetting the second charging power to be used. If the user selects such a reduced charging power, the assigned predicted charging duration can also be displayed at the same time. If this charging duration is too long for the user, the user can immediately manually change the second charging power to be selected according to the second charging mode.

[0042] According to another advantageous design of the present invention, in the second charging mode, the cooling power of the cooling system for cooling the energy storage device is limited or reduced to a second cooling power that is reduced relative to the maximum possible cooling power during the charging process, in particular wherein the cooling system comprises an active cooling device and a passive cooling device, wherein, in the second charging mode, the cooling power is provided only by the passive cooling device, and / or during charging according to the second charging mode, the active cooling device is deactivated or not activated, or the cooling power provided by the active cooling device during charging in the second charging mode is reduced relative to the first charging mode.

[0043] In this case, the cooling system can consist of active and passive components. That is, the cooling power can usually be provided actively or passively. In active battery cooling, in particular in refrigeration processes that achieve high cooling powers, the battery is cooled by means of a compressor through a refrigeration cycle. To a certain extent, this refrigeration process is independent of the ambient temperature. However, this process requires very high electrical power from the motor vehicle's compressor to provide the cooling power. In addition, there is also so-called passive battery cooling, which is achieved here by a passive cooling device. In this case, the battery is cooled by a low-temperature cooler of the motor vehicle. This cooling function is particularly related to the ambient temperature. For external temperatures starting from system-specific limit values ​​(e.g. 0°C), the performance is lower than that of active battery cooling.

[0044] Now, for the second charging mode, it can be provided that, for example, passive cooling is forced by the control device, and / or the cooling power is reduced to such an extent that passive cooling is automatically selected according to the selection logic currently implemented by the control device. In addition, it is conceivable to transmit passive cooling potential. In other words, it can be determined based on, for example, the current ambient temperature, what cooling power can currently be provided by the passive cooling device at most. Based on this, for example, the second charging power can be determined in such a way that the charging process can be carried out according to the second charging mode, that is, during this period, only the passive cooling device or the cooling power it provides is sufficient. For this purpose, for example, a corresponding, stored characteristic curve family can also be used, which links parameters such as the external temperature, the energy storage temperature and the second charging power. By this advantageous method, energy can be saved in two aspects at the same time, that is, not only by reducing the charging power itself, but also by selecting a particularly efficient charging power value for the second charging power, that is, selecting this charging power value in such a way that the passive cooling function is just enough to carry out the charging process according to the first charging power. That is, once active cooling is switched on, the energy loss increases suddenly simply due to the switching on of active cooling. By taking into account the cooling capacity of the respective cooling system and in particular the ambient temperature, a targeted selection of the first charging power which is lower than the power loss jump is achieved.

[0045] Preferably, the second charging power for the charging process in the second charging mode is determined in such a way that the maximum passive cooling power that can be provided by the passive cooling device according to the current ambient temperature and according to the current energy storage temperature and in particular according to the current coolant temperature is sufficient for completing the entire charging process according to the second charging power, but is insufficient for completing the entire charging process according to a third charging power, which is higher than the second charging power by a predetermined value, wherein the predetermined value is less than a predetermined limit value, in particular less than 50 kW, in particular 10 kW. As a result, the selected second charging power can be very close to the above-mentioned power loss jump.

[0046] In another advantageous embodiment of the invention, an activation request in the form of a detected actuation of an operating element assigned to the second charging mode is received by the control device. Such an operating element can be, for example, a physical switch or button or lever or the like, or also a virtual operating element, for example in the form of a menu item displayed on a touch screen, for example a touch screen of a motor vehicle and / or a user's mobile communication device. By actuating, for example, a charging selection operating element, for example a menu item, the user can also enter a submenu, a charging selection menu, in order to activate the second charging mode by actuating the corresponding operating element. This can be, for example, the slide adjuster described above.

[0047] It is also conceivable that the second charging mode is divided into further sub-modes, such as a moderate / medium energy-saving mode and a strong energy-saving mode. The sub-modes can be designed in such a way that the second efficiency assigned to the moderate energy-saving mode is less than the second efficiency assigned to the strong energy-saving mode. However, both second efficiencies are still lower than the maximum possible efficiency. This provides a higher flexibility. However, the number of subdivisions of the second efficiency is preferably limited to a small single-digit range, such as 2 to 3 or a maximum of 4 selectable sub-groups.

[0048] Furthermore, the invention relates to a control device for a motor vehicle, which is designed to carry out the method according to the invention or one of its embodiments.

[0049] Furthermore, the invention relates to a motor vehicle having a control device according to the invention or one of its embodiments.

[0050] The control device may have a data processing device or a processor device, which is configured to execute the implementation of the method according to the present invention. For this purpose, the processor device may have at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). As a microprocessor, in particular, a CPU (Central Processing Unit), a GPU (Graphical Processing Unit) or an NPU (Neural Processing Unit) may be used respectively. In addition, the processor device may have a program code, which is configured to execute the implementation of the method according to the present invention when executed by the processor device. The program code may be stored in a data memory of the processor device. The processor device may, for example, be based on at least one circuit board and / or at least one SoC (System on Chip).

[0051] For application cases or use cases that can occur in the method and are not explicitly described here, it can be provided that an error message is output by the method and / or a user feedback is requested and / or standard settings and / or predetermined initial values ​​are adjusted.

[0052] The invention also includes a development of the control device according to the invention, which has the features already described in conjunction with the development of the method according to the invention. For this reason, the corresponding development of the method according to the invention will not be described again here.

[0053] The motor vehicle according to the invention is preferably designed as a car, in particular a passenger car or a commercial vehicle, or as a bus or a motorcycle.

[0054] As another solution, the present invention also includes a computer-readable storage medium, which includes a program code, which, when executed by a computer or a computer group, prompts the execution of an embodiment of the method according to the present invention. The storage medium can be provided at least partially as a non-volatile data storage (e.g., flash memory and / or SSD-solidstate drive, solid state hard disk) and / or at least partially as a volatile data storage (e.g., RAM-randomaccess memory, random access memory). The storage medium can be arranged in a computer or a computer network. But the storage medium can also be run in the Internet as a so-called App store server and / or cloud server, for example. A processor circuit with, for example, at least one microprocessor can be provided by a computer or a computer network. The program code can be provided as a binary code and / or as an assembly code and / or as a source code of a programming language (e.g., C language) and / or as a program script (e.g., Python).

[0055] The present invention also includes combinations of features of the embodiments described. Therefore, the present invention also includes implementations which each have a combination of features of a plurality of the embodiments described, as long as these embodiments are not described as mutually exclusive. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The following describes an embodiment of the present invention.

[0057] Figure 1 A schematic diagram of a motor vehicle is shown, which is charged at a charging station according to an embodiment of the present invention;

[0058] Figure 2 A schematic flow chart is shown for illustrating a method for charging an energy storage device according to one exemplary embodiment of the present invention;

[0059] Figure 3 A schematic diagram of another flow chart for illustrating an embodiment of the present invention is shown;

[0060] Figure 4 A schematic diagram showing a user interface for activating an energy saving mode according to an embodiment of the present invention; and

[0061] Figure 5 A schematic diagram shows two temporally successive displays of a user interface for activating an energy-saving mode according to another exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0062] The embodiments described below are preferred embodiments of the present invention. In the embodiments, the various parts described in the embodiments are the individual features of the present invention that can be regarded as independent of each other, and these features also improve the present invention independently of each other. Therefore, the present disclosure should also include feature combinations that are different from the feature combinations of the illustrated embodiments. In addition, the embodiments may also be supplemented by other features in the features already described in the present invention.

[0063] In the figures, the same reference numerals respectively denote elements with the same function.

[0064] Figure 1 A schematic diagram of a motor vehicle 10 with a control device 12 according to an embodiment of the present invention is shown. The motor vehicle 10 has an energy storage device, for example a high-voltage battery 14. The high-voltage battery includes a plurality of cells 16, for example lithium-ion cells. In addition, the high-voltage battery also includes an electronic box 18 and a battery control unit 20, which can also be referred to as a battery management system. In addition, the motor vehicle includes an infotainment system 22 and a charging socket 24, through which the motor vehicle 10, in particular the battery 14, can be coupled to an energy source outside the vehicle, in this example, the energy source outside the vehicle is a charging post 26. In this case, the coupling of the vehicle 10 to the charging post 26 can be achieved via one or more wires, on the one hand, digital communication is provided via the wire, in this case, the digital communication is provided by the communication wire 28 shown by way of example, and on the other hand, electrical energy is transmitted via the wire, such as in this example, the current wire 30 shown by way of example transmits electrical energy. The wires 28, 30 can be integrated into a charging cable, through which the vehicle 10, in particular the charging socket 24, can be coupled to the charging post 26. Communication via a smartphone app 32, in particular via a cloud server 34, is also achieved via the infotainment system 22. In this case, the smartphone app 32 can be run on a mobile communication device of a user of the motor vehicle 10. The user is denoted by reference numeral 36. The vehicle 10 also includes a thermal system 38. The thermal system can include an active cooling device 40 and a passive cooling device 42. The energy storage device 14 can be cooled or temperature-controlled by means of the cooling devices 40, 42, in particular also during the charging process.

[0065] Figure 2 A flow chart is shown for illustrating a method for charging an energy storage device 14 according to an exemplary embodiment of the present invention. The method starts in step S10, in which the energy storage device 14 has an initial state of charge Z1 and is to be charged. Before the charging process begins, in step S12, the control device 12 checks whether an activation request for activating the energy-saving mode 12 has been received from the user. The user can activate the energy-saving mode 12 via a suitable interface, for example via the App 32 or the operating device 44 of the motor vehicle 10 (see Figure 1) expresses or inputs the energy-saving mode L2. If no such activation request is received, the control device 12 activates the first charging mode L1 for the subsequent charging process (step S14). In addition, in step S16, the control device determines the maximum possible charging power P1 for this first charging mode L1, from which the first overall efficiency η1 for the charging process to be carried out is derived. Subsequently, in step S18, the energy storage device 14 is charged to the desired, predefined final state of charge Z2 according to the first charging power P1.

[0066] However, if it is determined in step S12 that there is an activation request from the user for activating the energy-saving mode L2, the control device 12 first determines in step S20 the possible maximum charging power P1 for the charging process to be carried out. Subsequently, in step S22, the control device checks whether the possible maximum charging power P1 is greater than a preset limit value G, for example 50 kW. If it is not greater than the limit value, it goes to step S16. If it is greater than the limit value, it goes to step S24, according to which a second charging power P2 assigned to a second efficiency η2 is selected, the second efficiency being greater than the first efficiency η1, but less than the possible maximum efficiency ηmax. Subsequently, in step S26, the charging process is carried out with a slightly reduced charging power P2 until the final state of charge Z2 is reached.

[0067] For determining this second charging power P2 , a number of possibilities are now provided which will be explained in more detail below.

[0068] Figure 3 1 is a flow chart for illustrating a method according to another exemplary embodiment of the invention. The method starts again with step S10, in which the energy store 14 is to be charged starting from the initial charge state Z1 of the energy store. In step S12, it is checked again whether the energy saving mode or the efficiency mode is active or whether a corresponding activation request from the user 36 has been received. If this is not the case, i.e. the energy saving mode or the efficiency mode is not active or a corresponding activation request from the user has not been received, then the energy store 14 is ... Figure 2 The steps S14, S16 and S18 described above carry out a conventional charging process. Otherwise, in this example, it is first checked in step S28 whether the battery temperature T, that is, the temperature of the energy storage device 14, is within a certain theoretical range, for example, between 5°C and 35°C. If it is not within this theoretical range, it is transferred again to the conventional charging process according to steps S14, S16 and S18. Otherwise, if it is within the theoretical range, it is transferred to step S22' by checking again whether the possible maximum charging power P1 is higher than a certain limit value G or is within a certain value range, for example, between 50 kW and 280 kW. The upper limit of 280 kW is only optional at this time and can correspond to the possible maximum charging power P1, for example.

[0069] If this is not the case, that is, the maximum possible charging power P1 is not higher than the determined limit value G or is not within a determined value range, then the process also returns to the conventional charging method according to steps S14, S16 and S18. Otherwise, the process proceeds to step S30, in which the efficiency factor F is determined, in particular from a family of characteristic curves stored in the memory of the control device 12. The family of characteristic curves covers the battery initial temperature T and the maximum possible charging power P1 and outputs a corresponding factor F for each of the value pairs. Subsequently, in step S32, the vehicle or the energy storage device 14 is charged with the maximum charging power reduced by X%, that is, with the second charging power P2. Here, X% is generated from the percentage representation of the determined factor F. For example, the second charging power can be determined according to the following equation:

[0070]

[0071] Here, P Lade,max represents the maximum charging power currently possible in the combination of vehicle and charging pile, which corresponds to the first charging power P1 described, and P Lade,max,neu represents the maximum charging power that should be achieved after applying the efficiency factor, that is, the second charging power P2. X is the percentage representation of the efficiency factor F. For example, an efficiency factor F of 0.9 corresponds to 90%.

[0072] The charging manager or control device 12 then reduces the charging power P1 requested from the charging post 26 by a corresponding efficiency factor F.

[0073] Thus, in this example, the user 36 can first select the efficient charging function L2 in the infotainment system 22, and the infotainment system 22 sends this request to the charging manager, that is, the control device 12, which then implements the subsequent steps already described. For example, the efficiency factor F can be calculated in the characteristic curve family so that the energy loss caused by the second charging power is 20% lower than the original value at the corresponding maximum charging power P1. In addition, after the efficiency factor F has been determined, the corresponding predicted charging duration can also be determined and displayed to the user. In principle, the user 36 is always provided with the possibility of interrupting the energy-saving mode L2 and switching back to the normal first charging mode L1.

[0074] Figure 4A schematic diagram of a user interface 46 is shown, which can be displayed to the user, for example, in the form of a charging selection menu via the app 32 or the output device 44 of the motor vehicle 10, for example, to activate the energy-saving mode L2. First, the user 36 can have already started the charging process as usual, or has already plugged in the charging cable, and first obtains information on how long the usual charging process lasts at the connected facility 26. In this case, for example, "the charging process lasts about 22 minutes" can be displayed to the user. If the user 36 has more time anyway, the user can, for example, open the app 32 or open a corresponding menu on the display device 44 in the vehicle 10. The user can open the charging display via this interface 32, 44 and press, for example, the "extend charging time" button to reach the display 48 shown here. The user is thus provided with the possibility of extending the charging process according to the current charging power. The reference variable in this example is the target time, and the charging speed per unit power is then derived from the target time setting. In this case, the starting point 50 is the shortest achievable charging time t0 corresponding to the maximum charging power P1. tmax corresponds to the longest charging time resulting from the minimum settable charging power P2. In this case, a virtual slide regulator 52 can be displayed to the user, which the user can move, wherein such movement is indicated by an arrow 54. By moving the slide regulator 52, the user can extend the charging time accordingly. Optionally, the expected average or maximum charging power 56 for each current charging time setting t1, t2 can also be displayed to the user.

[0075] Advantages can be achieved in terms of battery protection by lower charging power and by increased efficiency, that is, by lower charging losses. Preferably, the charging time is extended only when the charging power is greater than a certain limit value (e.g. 50 kW). Preferably, after the charging is completed, the function automatically resets back to the shortest charging time t0.

[0076] Figure 5 A schematic diagram of two further temporally consecutive displays 48 ′, 48 ″ during or for activating the energy-saving mode L2 according to another exemplary embodiment of the present invention is shown. In this case, the user 36 can indirectly select the shortest target charging time, in particular again via the already described sliding control 52 . However, instead of directly setting a charging time extension, the user 36 can now directly select the second charging power P2 from a plurality of possible P2 values ​​by moving 54 the sliding control 52 . In addition, for each selectable P2 value, a predicted charging time 62 is shown to the user on the corresponding display 60 . Figure 5The upper figure in corresponds to the display 48 ', which is displayed when the maximum possible charging power P1 is selected. Then, the user starts to move the slide regulator 52 in the direction of the smaller charging power P2, as shown in Figure 5 As shown in the lower figure in FIG. As a result, the charging time 62 is correspondingly extended, such as in this example, the charging time is extended from 22 minutes to 26 minutes, that is, extended by 4 minutes.

[0077] The customer or user is given the possibility to extend the charging process according to the current charging powers P1, P2. Here, the reference variables are the maximum permissible charging powers P1, P2 and the charging duration 62, and the charging speed is derived from the available charging power P1 and the power limitation for the second charging power P2. The advantages are the same as described above. For example, this function is retained as a preset, that is to say a presetting, for subsequent charging processes, or it can also be automatically reset to the initial setting again after the charging process is completed. Subsequently, the infotainment system 22 sends the new shortest target charging time 62 to the charging manager 12, and the charging manager 12 implements the shortest target charging time 62 as follows: The charging manager determines the optimal charging curve taking into account the maximum permissible power provided by the second charging power P2.

[0078] In general, the example shows how the present invention can provide a method for improving efficiency and comfort during DC fast charging. When charging, the user has a "high-efficiency charging function" to choose from. When this function is activated, the maximum charging power is reduced in such a way that the user can, for example, save at least 20% of the charging energy loss that exists when the function is not activated. If the user can always tolerate a longer charging stay than usual, the high-efficiency charging function can be simply activated via the MMI (Multimedia Interface of the motor vehicle) or a mobile phone. The implementation through the characteristic curve family does not require a large amount of computing power. When a target SOC of 80% is reached, for example, 20% of the energy loss can be saved. In addition, simple settings for all charging scenarios can be achieved, which are easy to understand for the user and guarantee a minimum charging speed.

Claims

1. A method for charging an energy storage device (14) of a motor vehicle (10) at an electrical energy source (26) external to the vehicle from a determined initial charge state (Z1) of the energy storage device (14) to a determined final charge state (Z2) of the energy storage device (14), - when a first charging mode (L1) is set, the control device (12) controls the charging according to the first charging mode (L1) in such a way that the energy storage device (14) is charged from an initial state of charge (Z1) to a final state of charge (Z2) by an energy source (26) external to the vehicle at a first power (P1) and according to a first overall efficiency (η1), the first overall efficiency being the ratio of a first energy stored in the energy storage device (14) to a second energy obtained from the energy source (26) when charging from the initial state of charge (Z1) to the final state of charge (Z2), It is characterized in that - the control device (12) checks whether an activation request (54) has been received from a user (36) for activating a second charging mode (L2) representing an energy-saving mode (L2), - Under the first prerequisite that the control device (12) determines that an activation request has been received, the control device (12) activates a second charging mode (L2) and controls the charging process according to the second charging mode (L2) in such a way that the energy storage device (14) is charged from an initial state of charge (Z1) to a final state of charge (Z2) by an energy source (26) external to the vehicle according to a second overall efficiency (η2), which is higher than the first overall efficiency (η1) and lower than a determined maximum overall efficiency (ηmax).

2. The method according to claim 1, characterized in that The second charging mode (L2) is activated, in particular effectively activated, only under a second precondition, namely that a possible maximum charging power (P1) for charging, which corresponds in particular to the first charging power (P1), is greater than a predetermined threshold value (G), which is within a closed interval of 40 kW to 100 kW, for example within a closed interval of 40 kW to 80 kW.

3. The method according to any one of the preceding claims, characterized in that When the second charging mode (L2) has been activated, the control device (12) controls the charging process according to the second charging mode (L2) in such a way that the energy storage device (14) is charged from an initial state of charge (Z1) to a final state of charge (Z2) by an energy source (26) external to the vehicle at a second charging power (P2) that is reduced relative to the first charging power (P1), wherein before the charging process according to the second charging mode (L2) begins, the control device (12) predicts an estimated charging time (t1, t2, tmax; 62) according to the second charging power (P2) and outputs it to a user (36) via an output device (32; 44).

4. The method according to any one of the preceding claims, characterized in that According to the second charging mode (L2), a maximum possible charging power (P1) for charging, in particular as the first charging power (P1), is reduced in a predetermined manner, in particular by multiplying the maximum possible charging power (P1) by an efficiency factor (F), in particular - storing an allocation relation in a memory of the control device (12), the allocation relation allocating a plurality of different power ranges for a possible maximum charging power (P1) to corresponding efficiency factors of a plurality of efficiency factors (F), wherein the control device (12) selects the efficiency factor (F) according to the possible maximum charging power (P1) in accordance with the allocation relation; and / or, - A characteristic curve group is stored in a memory of the control device (12), which characteristic curve group links the parameters of energy storage device temperature (T), possible maximum charging power (P1) and efficiency factor (F), wherein the control device (12) selects the efficiency factor (F) according to the characteristic curve group as a function of the possible maximum charging power (P1) and the current energy storage device temperature (T) of the energy storage device (14).

5. The method according to any one of the preceding claims, characterized in that In order to activate the second charging mode (L2) by a user, a user input (54) is received by the control device (12), which specifies a charging time extension (t1, t2, tmax) compared to a possible shortest charging duration (t0) for a possible maximum charging power (P1), the control device (12) determines a second charging power (P2) which is reduced relative to the first charging power (P1) as a function of the charging time extension (t1, t2, tmax), and controls the charging process in the second charging mode (L2) as a function of the determined second charging power (P2).

6. The method according to any one of the preceding claims, characterized in that In order to activate the second charging mode (L2) by a user (36), a user input (54) is received by the control device (12), the user input specifying a charging power (P2) that is reduced relative to a possible maximum charging power (P1), and the control device (12) controls the charging process in the second charging mode (L2) according to the specified second charging power (P2).

7. The method according to any one of the preceding claims, characterized in that The control device (12) provides a display (48', 48") on an output device (32, 44), according to which different second charging powers (P2) that are reduced relative to a possible maximum charging power (P1) can be displayed to a user (36), wherein an assigned estimated charging duration (62) is displayed for each displayed second charging power (P2).

8. The method according to any one of the preceding claims, characterized in that In a second charging mode (L2), a cooling power of a cooling system for cooling the energy storage device (14) is limited or reduced during the charging process to a second cooling power which is reduced relative to a possible maximum cooling power, in particular the cooling system comprises an active cooling device (40) and a passive cooling device (42), wherein: - in the second charging mode (L2), the cooling power is provided exclusively by the passive cooling device (42) and / or during charging according to the second charging mode (L2), the active cooling device (40) is deactivated; or, During charging in the second charging mode (L2), the cooling power provided by the active cooling device (40) is reduced compared to the first charging mode (L1).

9. The method according to any one of the preceding claims, characterized in that The activation request (54) received by the control device (12) takes the form of detecting an actuation of an operating element (52) assigned to the second charging mode (L2).

10. A control device (12) for a motor vehicle (10), which is designed to carry out a method according to any of the preceding claims.

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