Method for operating a motor vehicle and motor vehicle

Abstract

The invention relates to a method for operating a motor vehicle (1) comprising a traction battery (2), a charging device (3) for charging the traction battery (2) with alternating current, and an ambient heat exchanger (4) of a cooling circuit (5) of a cooling device (6) by means of which a plurality of different cooling circuits (5, 7) can be formed, when the traction battery (2) is charged by the charging device (3), a charging cooling circuit (7) is designed as a cooling circuit among the cooling circuits (5, 7), by means of which heat is absorbed from a charging thermal element (9) which is connected in a heat-conducting manner to the charging device (3) and dissipated to a traction thermal element (10) which is connected in a heat-conducting manner to the traction battery (2), at this time, heat exchange with the environment heat exchanger (4) does not occur. The invention also relates to a motor vehicle (1).

Description

Technical Field

[0001] The invention relates to a method for operating a motor vehicle according to claim 1. The invention also relates to a motor vehicle according to claim 10. Background Art

[0002] Electrically driven motor vehicles usually have a traction battery. The traction battery can be charged with the aid of a suitable charging infrastructure, wherein both alternating current charging and direct current charging are possible. Charging powers of 7.4 kW, 11 kW and 22 kW are usually used as standards. During charging, heat is generated in the vehicle-side charging device, for example due to resistance.

[0003] In the prior art, the heat generated in the charging device is discharged through a vehicle cooler, which exchanges heat with the environment of the motor vehicle, especially the ambient air. In addition, DE102018110396A1 shows a DC fast charging and air conditioning control system for a hybrid electric vehicle. The disadvantage of the prior art is, for example, that the heat generated in the charging device during charging is discharged to the environment without being utilized. Summary of the invention

[0004] The object of the present invention is to provide a method and a motor vehicle, by means of which AC charging of a traction battery of a motor vehicle can be carried out particularly efficiently.

[0005] This object is achieved by the subject matter of the independent claims. Advantageous embodiments and developments of the invention are the subject matter of the dependent claims, the description and the drawings.

[0006] A first aspect of the invention relates to a method for operating a motor vehicle, in particular the motor vehicle is designed as a passenger car. The method according to the invention is used for operating a motor vehicle, which comprises a traction battery, a charging device for charging the traction battery with alternating current, and an ambient heat exchanger of a cooling circuit of a cooling device, by means of which a plurality of different cooling circuits can be formed or switched, wherein when the traction battery is charged by the charging device, a charging cooling circuit is formed as one of the cooling circuits, by which heat is absorbed from a charging heat element connected thermally to the charging device and is dissipated to a traction heat element connected thermally to the traction battery, and in this case no heat exchange with the ambient heat exchanger or in particular heat exchange between the charging heat element and the ambient heat exchanger occurs.

[0007] The ambient heat exchanger can be, for example, a vehicle cooler, which exchanges heat with the environment of the motor vehicle, in particular exchanges heat with the ambient air. A coolant flows through each cooling circuit of the cooling device. The traction battery, for example, comprises a plurality of battery cells or cells and is used to drive an electric drive of the motor vehicle. The charging device is designed to convert an alternating current provided from a source outside the vehicle via a charging line into a direct voltage or direct current suitable for charging the battery. The charging thermal element can be, in particular, a heat exchanger and / or can be, for example, designed as a housing, in particular made of metal, which at least partially surrounds the charging device and has openings through which the coolant of the cooling device can flow. The traction thermal element is, for example, also a heat exchanger, which is designed to exchange heat between the traction battery and the cooling device.

[0008] In other words, in the method according to the invention, the motor vehicle comprises a traction battery, which is connected to a cooling device via a traction heat element in a heat-exchanging manner, and a charging device, which converts alternating current into direct current and can supply it as charging current to the traction battery, and which is connected to the cooling device via the cooling element in a heat-conducting manner, wherein the cooling device comprises a vehicle cooler and, for example, a switching device, by means of which a plurality of different cooling circuits can be switched, wherein a cooling circuit is formed when the traction battery is charged by the charging device, so that heat is absorbed at the cooling element and dissipated to the traction heat element, and no heat exchange with the vehicle cooler occurs in this case. That is, the waste heat generated during charging, for example due to a resistor in the charging device, is not dissipated to the environment of the vehicle via the vehicle cooler, but is in particular used to charge the traction battery with heat.

[0009] In contrast to the prior art, in which the waste heat is removed by the vehicle radiator, the waste heat is thus efficiently transported during AC charging to the storage or traction battery and utilized, and additionally or alternatively to the vehicle interior.

[0010] Therefore, multiple advantages are generated. Therefore, the intelligent utilization of the waste heat of the charging device is realized, and the charging device is especially designed as a central control unit, so that active storage heating can be avoided advantageously. In addition, an increase in the discharge power is allowed in the storage after AC charging, and the storage is especially designed as a high-voltage storage. In addition, the following advantages are generated: even in the case of a long stop phase, a particularly high cell temperature of the cells in the traction battery is allowed at the start. In addition, a reduction in the cell variation range can occur, especially at the start, so that the life of the traction battery can be increased. Similarly, a collective increase in the temperature of the high-voltage storage can be achieved by the method, which can also lead to a particularly long life. In addition, the individual heating of the high-voltage storage or the traction battery can be avoided after the charging process, so that the motor vehicle can be operated particularly efficiently. In addition, the thermal level of the storage can be used in a targeted manner for heat pump operation, which also leads to particularly high efficiency during the operation of the motor vehicle. In addition, AC charging can be used in active interior heating for heating the interior, so that a particularly efficient operation of the motor vehicle is also allowed. In general, the waste heat generated by AC charging during the charging process can be advantageously utilized.

[0011] In an advantageous embodiment of the invention, during the charging of the traction battery, the interior heating element or the passenger compartment heating element is arranged in a charging cooling circuit having a charging heating element and a traction heating element. In other words, the cooling circuit is formed or connected by means of a cooling device so that the interior heating element (which forms, for example, a refrigerator or a heater for the vehicle interior) can be supplied with waste heat generated at the charging device during charging. This results in the following advantage: if the vehicle interior needs to be heated, this heating can be carried out particularly effectively by means of the method, so that the heat generated during charging is not dissipated in the vehicle environment, but rather heats the vehicle interior.

[0012] In a further advantageous embodiment of the invention, the charging cooling circuit of the cooling device is formed or switched on in dependence on the ambient temperature and / or the battery temperature and / or the interior temperature. In other words, the charging cooling circuit is formed in dependence on the temperature, taking into account different temperatures. Thus, on the one hand, the ambient temperature, in particular the outside air temperature or the temperature of the environment in which the motor vehicle is located, can be used. Thus, for example, at particularly low temperatures, a charging cooling circuit can be formed in order to heat the traction battery. On the other hand, at particularly high temperatures (at such temperatures, the battery temperature of the traction battery is already in a temperature corridor, which is necessary for the favorable operation of the traction battery or the motor vehicle), conventional charging is used during charging, so that the waste heat is discharged via the vehicle cooler and is not used to heat the traction battery. In addition or as an alternative, the formation of the charging cooling circuit can be dependent on the interior temperature of the vehicle interior, so that the charging cooling circuit can be used to heat the vehicle interior. In this case, an embodiment can be provided in which the charging cooling circuit is formed in such a way that the interior heat element is mainly supplied with waste heat from the charging device and the traction heat element is only slightly or not even supplied with heat from the charging device. This results in the advantage that, depending on the particular temperature mentioned, a suitable, particularly advantageous charging can be used accordingly.

[0013] In another advantageous embodiment of the present invention, an extended charging cooling cycle is formed in relation to the ambient temperature and / or the operating temperature and / or the interior temperature, in which an ambient heat exchanger is provided. In other words, the charging cooling cycle formed by the charging heat element and the traction heat element and, for example, also by the interior heat element can additionally integrate an ambient heat exchanger that was not originally provided. This can be meaningful, for example, in the following situation: the battery temperature has reached a certain temperature, so that when heat is continued to be supplied via the traction heat element, the temperature corridor suitable for the advantageous operation of the traction battery is exceeded, for example, by the charging heat element. Therefore, in order to ensure particularly high efficiency and at the same time avoid overheating, an ambient heat exchanger can be included. This results in the following advantage: the method can be used particularly advantageously for the operation of a motor vehicle.

[0014] In a further advantageous embodiment of the invention, the charge cooling cycle and / or the extended charge cooling cycle is formed in dependence on the charge state of the traction battery. In other words, the charge state of the battery (SoC for short) is considered in proportion to the battery capacity, and the charge cooling cycle or the extended charge cooling cycle is formed accordingly. As a result, for example, as the charge state increases, the traction battery is charged with a smaller charging power in order to keep the service life of the traction battery particularly long. If, for example, the required charging power can be reduced due to the charge state of the traction battery, then it may no longer be necessary to load the traction heat element with waste heat, which can be advantageously taken into account by means of the method. As a result, the following advantage results: the traction battery can be charged particularly advantageously and, for example, intactly.

[0015] In another advantageous embodiment of the present invention, the charging cooling cycle and / or the extended charging cooling cycle are formed in relation to a planned change in the operating state of the motor vehicle. In other words, when a change in the operating state of the motor vehicle is set, the charging cooling cycle and / or the extended charging cooling cycle are switched on. At this time, the change in the operating state can be, in particular, a conversion of a parked or charging motor vehicle into a driving mode. Thus, for example, it can be provided that the motor vehicle should be started at a certain clock time and this information is stored, for example, in a control device, which is, in particular, connected to a charging device to exchange information, or which controls the charging device. With this information, the traction battery can now advantageously reach its operating temperature at a suitable clock time by the method. This can be achieved by correspondingly forming a charging cooling cycle or an extended charging cooling cycle during charging, or at least taking this into account. Thus, the following advantage is produced: the motor vehicle can be operated particularly advantageously.

[0016] In a further advantageous embodiment of the invention, the charging cooling cycle and / or the extended charging cooling cycle is formed in dependence on the charging power provided by the charging device. In other words, the charging cooling cycle and / or the extended charging cooling cycle is formed in dependence on the actual charging power provided to the charging device, for example from a wall box. Thus, in the case of a particularly high provided charging power, an extended charging cooling cycle can be formed, whereas, for example, in the case of a low charging power, only a charging cooling cycle is formed. This results in the following advantage: the motor vehicle can be charged particularly advantageously.

[0017] In a further advantageous embodiment of the invention, a charge cooling cycle and / or an extended charge cooling cycle is formed in dependence on at least one, for example, thermal, cell variation range of at least one cell of the traction battery. In other words, the traction battery comprises a plurality of cells or battery cells, which are monitored, for example, in particular by a battery line system, so that the cell voltages of several cells and a plurality of cell temperatures are known. If different temperatures occur in a cell, cell variation ranges can occur in dependence on the temperature gradients that are thus present in the cell, which shorten the life of the battery. This can be avoided or reduced by controlled charging using the method described, so that a charge cooling cycle or an extended charge cooling cycle is formed in dependence on the cell variation range. This results in the advantage that the traction battery can be charged in such a way that the life of the traction battery is particularly long.

[0018] In another advantageous embodiment of the present invention, the formation of different cooling cycles of the cooling device, in particular the formation of a charging cooling cycle and / or an extended charging cooling cycle, is achieved by at least one valve of the corresponding cooling cycle or by means of the valve. In other words, the cooling device includes at least one valve, which is arranged so that the pipelines through which the coolant flows of each individual heat element (i.e., the traction heat element, the charging heat element and / or the interior heat element) and the ambient heat exchanger can be connected to each other via the at least one valve. As a result, the cooling device can be designed particularly simply and thus with few components and / or flexibly. This results in the following advantage: the method can be implemented particularly simply.

[0019] A second aspect of the invention relates to a motor vehicle with a traction battery. The motor vehicle according to the invention comprises a traction battery and a charging device for charging the traction battery with alternating current and an ambient heat exchanger for exchanging heat with a cooling circuit of a cooling device, wherein a plurality of different circuits can be formed by the cooling device, wherein when the traction battery is charged by the charging device, a charging cooling circuit is formed, through which heat can be absorbed from a charging thermal element connected thermally to the charging device and can be dissipated to a traction thermal element connected thermally to the traction battery, and in this case, no heat exchange with the ambient heat exchanger occurs. Advantageous embodiments and developments of the first aspect of the invention can be regarded as advantageous embodiments and developments of the second aspect of the invention, and vice versa.

[0020] Further features of the invention are derived from the claims, the drawings and the description of the drawings. The features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the drawings and / or the features and feature combinations shown individually in the drawings can be used not only in the respectively described combination but also in other combinations or individually. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will now be explained in more detail with the aid of preferred embodiments and with reference to the accompanying drawings. The accompanying drawings are as follows:

[0022] Figure 1 A schematic diagram showing a motor vehicle having a traction battery, a charging device and a cooling device, which motor vehicle implements a method for charging a traction battery according to the prior art;

[0023] Figure 2 Display Press Figure 1 Schematic diagram of a motor vehicle, in which an advantageous method for charging a battery is implemented;

[0024] Figure 3 Display Press Figure 2 a schematic diagram of a motor vehicle, in which an alternative embodiment of the advantageous method is implemented; and

[0025] Figure 4 A schematic diagram is shown which illustrates the operating status of an advantageous method. DETAILED DESCRIPTION

[0026] Figure 1 The schematic diagram shows a motor vehicle 1 which comprises a traction battery 2 , a charging device 3 for charging the traction battery 2 , and an ambient heat exchanger 4 for exchanging heat with the surroundings of a cooling circuit 5 of a cooling device 6 , by means of which a plurality of different cooling circuits 5 , 7 can be formed or switched.

[0027] In the motor vehicle 1, respective electric drive trains 8 for the front and rear axles are driven by electrical energy provided by a traction battery 2. The traction battery 2 can be charged by means of alternating current via a charging device 3, which generates heat, for example due to resistance in the charging device 3 and conversion into direct current, which needs to be dissipated.

[0028] For heat dissipation, a charging heat element 9 is used, which is in particular designed, for example, as a housing of the charging device 3 through which a coolant can flow. The heat is now dissipated to the cooling circuit 5 via the charging heat element, which is shown in FIG. Figure 1 During conventional charging according to the prior art, the heat generated by the ambient heat exchanger 4 is absorbed and released to the environment of the motor vehicle 1 .

[0029] The cooling circuits 5 and 7 of the cooling device are switched on or formed in Figures 1 to 3 In order to identify the cooling circuit 5 which is switched on or formed accordingly, it is not depicted with a dashed line. The dashed line area is accordingly not used as a cooling circuit in the present case.

[0030] In order to enable the traction battery 2 to be charged advantageously and the motor vehicle 1 to be operated advantageously, in addition to the motor vehicle 1, a method for operating the motor vehicle 1 is described, wherein when the traction battery 2 is charged by the charging device 3, a charging cooling circuit 7 is formed, by which heat is absorbed from a charging thermal element 9 connected thermally to the charging device 3 and dissipated to a traction thermal element 10 connected thermally to the traction battery 2, and no heat exchange with the ambient heat exchanger 4 occurs at this time, for which reason it can be seen that Figure 2 and Figure 3 .

[0031] The respective cooling circuits 5, 7 are in particular lines through which a coolant can flow, which are respectively connected to the ambient heat exchanger 4, the charging heat element 9 and / or the traction heat element 10. A pump 12 can be provided for conveying the coolant. In order to form or switch the respective cooling circuit topology by the cooling device 6 in a particularly advantageous manner, at least one valve 12 is advantageously provided, by which the respective cooling circuit topology can be switched. Figure 2 or Figure 3 Cooling cycle 5 or charging cooling cycle 7 and extended charging cooling cycle.

[0032] The method for operating motor vehicle 1 and the formation of charge cooling cycle 7 can advantageously be carried out as a function of the ambient temperature and / or the battery temperature of traction battery 2 and / or the interior temperature of the vehicle interior of motor vehicle 1 .

[0033] It can therefore be advantageous to operate the traction battery 2 in a temperature corridor which, for example, optimally contains particularly favorable charging temperatures and / or particularly favorable operating temperatures, so that if the temperature of the traction battery 2 is already at the upper end of the temperature corridor, conventional charging can be preferred.

[0034] Furthermore, the vehicle interior can be heated, for example, in dependence on the interior temperature, so that, for example, the interior heating element 13 formed by means of a refrigerator is heated, so that in the method described, as in Figure 3 As shown in FIG. 1 , the charging cooling circuit 7 is formed so that when the traction battery 2 is charged, the interior heat element 13 is arranged in the charging cooling circuit 7 having the charging heat element 9 and the traction heat element 10 , so that the waste heat of the charging device 3 can be dissipated to the traction heat element 10 and the interior heat element 13 via the charging heat element 9 .

[0035] The method described provides several advantages, which allow two Figure 2 and Figure 3. On the one hand, it is possible to intelligently utilize the waste heat of the charging device 3, which is in particular designed as a central unit (CCU), wherein the waste heat is generated by charging with, for example, 7.4, 11 or 22 kW of AC current. It is possible to avoid, for example, actively heating the storage device with an electric heater and / or to avoid increased power loss of the traction motor during AC charging. This results in an increase in the discharge power after AC charging on the traction battery 2. In addition, even after a longer stop phase, an increased cell temperature is possible at the start. Here, the cell temperature is the temperature of the cells of the traction battery 2.

[0036] Furthermore, it is possible to reduce the cell range, in particular at the start of driving of the motor vehicle 1. It is thus possible to implement a charging cooling circuit 7 and / or an extended charging cooling circuit 7 in dependence on at least one cell range of at least one of the cells of the traction battery 2. It is indicated here that an extended charging cooling circuit can be formed in dependence on a temperature among the temperatures mentioned (i.e. the cell temperature or the battery temperature and / or the ambient temperature, also in combination with the interior temperature), in which an ambient heat exchanger 4 is provided, so that in addition to the advantageous connection of two heat elements (in particular the charging heat element 9 and the traction heat element 10), heat can be additionally transferred through the ambient heat exchanger 4, which is in particular designed as a vehicle cooler.

[0037] It is also advantageous to form the charge cooling cycle 7 and / or the extended charge cooling cycle in dependence on the charge state, i.e. the charge state of the traction battery 2. Additionally or alternatively, the charge cooling cycle 7 and / or the extended charge cooling cycle can be formed in dependence on a planned change in the operating state of the motor vehicle 1. Furthermore, the charge cooling cycle 7 and / or the extended charge cooling cycle 7 can be formed in dependence on the charging power provided by the charging device 3.

[0038] The advantageous range for charging by the method described or the advantageous range for operating the motor vehicle 1 by means of charging with the alternating current generated by the charging device 3 is schematically shown at Figure 4 This is summarized in the chart.

[0039] The diagram shows that, in particular, the refrigerator, that is, the interior thermal element 13, is bypassed or circumvented (and thus Figure 2 Charging possible during the cooling cycle 7 switched on).

[0040] A first axis 14 pointing downwards shows the charge state of the traction battery 2, wherein a low charge state SoC A and a high charge state SoC B are shown. Between these two charge states there is a range in which the method presented can be particularly advantageously implemented for charging the traction battery 2 by means of an alternating current via the charging device 3. The upper axis 15 of the two horizontal axes shows the temperature of the traction battery 2, whereas the lower axis 16 of the two axes shows the charging power associated with the electrical connections and which can be provided by the charging device 3.

[0041] therefore, Figure 4 The shaded area of ​​represents a range in which charging with the aid of the described method is particularly advantageous. In this case, the method is therefore particularly effective when the temperature of the traction battery 2, i.e. the battery temperature or the cell temperature, is within a specified target corridor. In addition, the outside temperature or the ambient temperature should be below a certain value, or the temperature target corridor should be adapted to the outside temperature. In addition, the method can be advantageously applied at a certain minimum value of the charging power and / or below a certain cell temperature. In addition, the state of charge can define an entry below SoC A or an exit above SoC B. In addition, the method can be used with the aid of a trigger or when a planned departure time is recognized so that the temperature of the traction battery 2 is within the temperature corridor at the time of departure.

[0042] Furthermore, the cooling circuit 5, 7 can be operated as a heat pump by the method. Thus, the target temperature of the high voltage storage device can be, for example, between 30°C and 35°C, and depending on the range of the ambient temperature, the cooling device 6 can be operated accordingly.

[0043] The method described and the motor vehicle 1 described thus result in a particularly advantageous use of the waste heat. Several advantages are achieved in this regard: the temperature resistance of the traction battery 2 is increased; heating of the storage device is avoided during and after charging; and additional heating of the traction battery 2 to operating temperature is eliminated. Furthermore, an increase in the discharge power after charging can be achieved.

[0044] For example, at a charging power of 11 kW, approximately 500 watts of waste heat can be generated at the charging device 3, so that a significantly higher temperature gradient of the storage device is formed by actively supplying waste heat. The described method and the described motor vehicle 1 disclose an optimization for AC charging of pure electric vehicles and / or hybrid vehicles.

[0045] Reference numerals list

[0046] 1Motor Vehicle

[0047] 2 Traction batteries

[0048] 3. Charging device

[0049] 4Environmental heat exchanger

[0050] 5 Cooling cycle

[0051] 6 Cooling device

[0052] 7 Charge Cooling Cycle

[0053] 8 Drivetrain

[0054] 9 Charging thermal element

[0055] 10 Traction heating element

[0056] 11 valves

[0057] 12 Pumps

[0058] 13 Inner chamber heat element

[0059] 14 Charge status axis

[0060] 15Battery temperature axis

[0061] 16 Charging power axis

Claims

1. A method for operating a motor vehicle (1), the motor vehicle comprising a traction battery (2), a charging device (3) for charging the traction battery (2) with alternating current, and an ambient heat exchanger (4) of a cooling circuit (5) of a cooling device (6), by means of which a plurality of different cooling circuits (5, 7) can be formed, wherein: When the traction battery (2) is charged by the charging device (3), a charging cooling circuit (7) is formed as one of the cooling circuits (5, 7), through which heat is absorbed from a charging thermal element (9) thermally connected to the charging device (3) and dissipated to a traction thermal element (10) thermally connected to the traction battery (2), and in this case no heat exchange with an ambient heat exchanger (4) takes place.

2. The method according to claim 1, characterized in that When the traction battery (2) is charged, the interior heating element (13) is arranged in a charging cooling circuit (7) having a charging heating element (9) and a traction heating element (10).

3. The method according to claim 2, characterized in that The charging cooling cycle (7) is formed according to the ambient temperature and / or the battery temperature and / or the interior temperature.

4. The method according to any one of the preceding claims, characterized in that An extended charge cooling circuit (7) is formed as a function of the ambient temperature and / or the battery temperature and / or the interior temperature, in which the ambient heat exchanger (4) is arranged.

5. The method according to any one of the preceding claims, characterized in that The charge cooling cycle (7) and / or the extended charge cooling cycle (7) is formed as a function of the charge state of the traction battery (2).

6. The method according to any one of the preceding claims, characterized in that The charge cooling cycle (7) and / or the extended charge cooling cycle (7) are formed as a function of a planned change in operating state of the motor vehicle (1).

7. The method according to any one of the preceding claims, characterized in that The charging cooling cycle (7) and / or the extended charging cooling cycle (7) is formed in dependence on the charging power provided by the charging device (3).

8. The method according to any one of the preceding claims, characterized in that The charge cooling cycle (7) and / or the extended charge cooling cycle (7) is formed in dependence on at least one cell variation range of at least one cell of the traction battery (2).

9. The method according to any one of the preceding claims, characterized in that Different cooling circuits (5, 7), in particular the charge cooling circuit (7) and / or the extended charge cooling circuit (7), of a cooling device (6) are formed by means of at least one valve (11).

10. A motor vehicle (1) comprising a traction battery (2), a charging device (3) for charging the traction battery (2) with alternating current, and an ambient heat exchanger (4) of a cooling circuit (5) of a cooling device (6), by means of which a plurality of different circuits (5, 7) can be formed, wherein: When the traction battery (2) is charged by the charging device (3), a charging cooling circuit (7) is formed, through which heat can be absorbed from a charging heat element (9) thermally connected to the charging device (3) and can be dissipated to a traction heat element (10) thermally connected to the traction battery (2), without heat exchange with an ambient heat exchanger (4).

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