DE102021209389B3 - Electrical system for a motor vehicle and motor vehicle - Google Patents

Abstract

The invention relates to a vehicle electrical system (20) for a motor vehicle (2) having a high-voltage energy store (6) with two storage banks (10), the two storage banks (10) being connected to an additional switching device (30), the additional - Switching device (30) has a supply output (34) for supplying a number of high-voltage consumers (22) and wherein the additional switching device (30) is set up to enable two switching states, namely a first switching state in which the two memory banks (10) and the supply output (34) are connected in parallel, and a second switching state in which the two memory banks (10) and the supply output (34) are connected in series.

Description

The invention relates to an on-board electrical system for a motor vehicle having a high-voltage energy storage device with two storage banks. The invention also relates to a motor vehicle with such a vehicle electrical system.

Electrical systems for motor vehicles with a high-voltage energy storage device are known per se and, for example, in DE 10 2019 204 173 A1 , the DE 10 2017 114 988 A1 , the DE 10 2018 214 085 A1 and the DE 10 2018 000 491 A1 described. They are mainly installed in electric vehicles.

For the charging of electric vehicles at charging stations, in particular charging columns, using DC voltage, two voltage classes or voltage levels are currently provided, namely 400 V and 800 V. If the electrical system of an electric vehicle is only designed for one of these voltage classes or voltage levels, then only a part of the Charging stations are used to charge the motor vehicle.

The invention is based on the object of specifying an advantageously designed vehicle electrical system for a motor vehicle and an advantageously designed motor vehicle.

This object is achieved by an on-board electrical system having the features of patent claim 1 and by a motor vehicle having the features of patent claim 10 . The advantages and preferred configurations listed with regard to the vehicle electrical system can also be transferred to the motor vehicle and vice versa. Advantageous configurations with expedient developments of the invention are specified in the dependent patent claims.

The vehicle electrical system according to the invention is designed for a motor vehicle and is accordingly part of a motor vehicle in the installed state. The motor vehicle according to the invention in turn has a corresponding vehicle electrical system and is typically designed as an electric vehicle or hybrid vehicle. This means that the motor vehicle usually has at least one electric motor, by means of which propulsion can be generated, ie with which a longitudinal acceleration for the motor vehicle can be specified.

The vehicle electrical system also has a high-voltage energy store and is preferably set up in such a way that the high-voltage energy store can be charged using a DC voltage that is provided by a charging station of the type mentioned at the outset. The vehicle electrical system is typically compatible with the two voltage classes or voltage levels mentioned at the outset, namely 400 V and 800 V. This means that the vehicle electrical system is preferably set up in such a way that the high-voltage energy store can be charged with either 400 V or 800 V. The high-voltage energy storage device has two storage banks for this purpose in particular.

In this case, the two memory banks are connected to an additional switching device in the vehicle electrical system or linked to an additional switching device. That additional switching device in turn has a supply output for supplying a number of high-voltage consumers with DC voltage. Furthermore, the additional switching device is set up to enable at least two switching states, namely a first switching state and a second switching state. The two memory banks and the supply output are connected in parallel in the first switching state, and the two memory banks and the supply output are connected in series in the second switching state.

The additional switching device is preferably designed as a simple switching device. This means that the switching device has a number of semiconductor switches which are formed, for example, by IGBTs (IGBT: insulated-gate bipolar transistor). With the aid of these semiconductor switches, only one connection of the memory banks is preferably made possible, so that these can be used as two voltage sources or two current sources either in a parallel connection or in a serial connection for the supply output. In some cases, a third switching state is also possible, in which the supply output is separated from the memory banks. In addition, however, the additional switching device preferably has no (DC) voltage converter, i.e., for example, no charge pump, no step-up converter, no step-down converter, etc.

The additional switching device means that the vehicle electrical system is then set up, in particular, to optionally provide two different DC voltages as supply voltages at the supply output for supplying the high-voltage consumers. This means that a first supply voltage is provided at the supply output with the first switching state and that a second supply voltage is provided at the supply output with the second switching state. The first supply voltage is usually in the range of 300 V to 500 V, in particular in the range of 350 V to 450 V, and the second supply voltage is usually in the range of 700 V to 900 V, in particular in the range of 750 V to 850 V supply voltage voltage typically in good approximation twice the first supply voltage. The two supply voltages are preferably at the voltage levels mentioned at the outset, namely 400 V and 800 V. Switching between the first and the second switching state then requires switching between the 400 V voltage level and the 800 V voltage level. The exact supply voltages here usually vary in Depending on the state of charge of the high-voltage energy store and/or depending on the state of use of the high-voltage energy store.

The storage banks of the high-voltage energy store are preferably designed as units with exactly two external connection poles, namely a plus pole and a minus pole. The additional switching device is then preferably connected to the four outer connection poles of the two memory banks. Each memory bank in turn has a multiplicity of accumulator cells which are connected to one another within the memory bank and are in the form of lithium-ion accumulator cells, for example. In addition, the two memory banks are preferably constructed in essentially the same way, so that the two memory banks can be regarded as voltage sources or current sources of the same type.

Also typical is an embodiment in which the high-voltage energy store is designed as a module. In this case, that module typically has a housing, ie in particular a housing which closes off the module from the outside. Such a module is then typically prefabricated and connected to other components of the vehicle electrical system to produce the vehicle electrical system, for example via one or more cables.

Depending on the variant, the additional switching device is also part of the high-voltage energy storage device. Alternatively, it is part of a separate assembly, in particular an additional module. A corresponding additional module then typically has a housing, in particular a housing, which closes off the additional module from the outside.

If the additional switching device is now part of such an additional module, then the additional module and the high-voltage energy store are typically connected to one another via one or more cables. Depending on the application, a corresponding cable has a plug connector on at least one end.

The vehicle electrical system also has a DC charging input, via which the high-voltage energy store can be charged using direct current. The DC charging input is supplemented by a basic switching device, which in turn is set up to enable two switching states, namely a first switching state and a second switching state. The basic switching device is set up such that the two memory banks and the DC charging input are connected in parallel in the first switching state and the two memory banks and the DC charging input are connected in series in the second switching state. In this way, a vehicle electrical system is then implemented in which the high-voltage energy store can be charged via one and the same DC charging input with two different DC voltages as charging voltages.

The high-voltage energy store can then typically be charged via the DC charging input by means of a charging voltage that is provided by a charging station of the type mentioned at the outset. The vehicle electrical system is preferably compatible with the two voltage classes or voltage levels mentioned at the outset, namely 400 V and 800 V, so that the high-voltage energy storage device can be charged with either 400 V or 800 V.

The basic switching device is also preferably designed as a simple switching device. This means that the base switching device has a number of semiconductor switches which are formed, for example, by IGBTs (IGBT: insulated-gate bipolar transistor). With the aid of these semiconductor switches, it is preferably only possible to interconnect the memory banks, so that the charging voltage at the DC charging input is present either at each memory bank or at both memory banks together. In some cases, a third switching state is also possible, in which the DC charging input is separated from the memory banks. In addition, however, the basic switching device preferably has no (DC) voltage converter, i.e., for example, no charge pump, no step-up converter, no step-down converter, etc.

The basic switching device is also preferably part of the high-voltage energy store, at least if it is designed as a module. This means that the basic switching device is preferably positioned within a housing that closes off the high-voltage energy store from the outside. In contrast, the additional switching device is preferably arranged outside such a housing and is part of a separate module.

It is also advantageous if the additional switching device is connected to the two memory banks via an intermediate tap between the two memory banks and the basic switching device. Thus, the intermediate tap of the additional switching device then leads to the outputs of the Voltages present in memory banks are independent of the switching state of the base switching device.

In addition, it is advantageous if the vehicle electrical system has an AC charging input for charging the high-voltage energy store using AC voltage. The AC charging input is preferably connected to the two memory banks via an intermediate tap between the two memory banks and the basic switching device, ie in particular the aforementioned intermediate tap, and/or via the additional switching device. This approach of connecting an AC charging input to the two memory banks via an intermediate tap and/or via an additional switching device is viewed as an independently inventive approach. Accordingly, an application directed thereto or a divisional application directed thereto remains reserved.

According to an advantageous embodiment, the DC charging input and the AC charging input are then connected to the two memory banks via different switching devices, with each of these switching devices, i.e. the basic switching device on the one hand and the additional switching device on the other, optionally having a parallel Connection or a serial connection of the two memory banks allows.

It is also expedient if the vehicle electrical system is set up in such a way that charging operation is enabled, in which the high-voltage energy store is charged, and that in this charging operation a supply voltage is provided at the supply output to supply the number of high-voltage consumers. In an advantageous development, a first charging mode is also made possible, in which the high-voltage energy store is charged via the DC charging input, and a second charging mode, in which the high-voltage energy store is charged via the AC charging input. In this case, a supply voltage is then preferably provided at the supply output both in the first charging mode and in the second charging mode. In this case, the supply voltage is typically independent of the charging operation and depends only on the switching state of the additional switching device.

Such a configuration of the vehicle electrical system is particularly advantageous if at least one high-voltage consumer connected to the supply output is designed as an auxiliary unit for temperature control of the high-voltage energy store, i.e. for bringing the high-voltage energy store into a predetermined temperature window and/or within a specified temperature range. In this case, for example, a heating element, a coolant pump or an electric refrigerant compressor then forms the at least one high-voltage consumer.

Alternatively or additionally, at least one high-voltage consumer connected to the supply output is designed to control the temperature of the interior of the motor vehicle. In this case, for example, a heating element, a coolant pump or an electric refrigerant compressor then in turn forms the at least one high-voltage consumer.

• 1 ein Elektrofahrzeug mit einem Bordnetz, welches einen Hochvolt-Energiespeicher und ein Speicherzusatzmodul aufweist, und
• 2 das Speicherzusatzmodul.

Further advantages, features and details of the invention result from the claims, the following description of preferred embodiments and with reference to the schematic drawings. Show in it:

• 1 an electric vehicle with an on-board electrical system, which has a high-voltage energy storage device and an additional storage module, and
• 2 the storage add-on module.

Corresponding parts are provided with the same reference numbers in both figures.

An example described below and in 1 The motor vehicle 2 outlined is designed as an electric vehicle and has two electric motors, not shown, with which propulsion can be generated, with which a longitudinal acceleration for the motor vehicle 2 can therefore be specified. In this case, each electric motor is connected to an electric motor supply output 4 of a high-voltage energy store 6 in order to be supplied with electrical energy.

In the exemplary embodiment, the high-voltage energy store 6 is designed as a module and has a housing 8 which closes off the high-voltage energy store 6 from the outside. In the housing 8, two memory banks 10 are arranged, according to 1 are designed as units with exactly two outer connection poles 12, namely a positive pole and a negative pole. Each memory bank 10 in turn has a large number of accumulator cells 14 (in 1 4 are shown as an example), which are connected to one another within the memory bank 10 and are designed, for example, as lithium-ion accumulator cells. In the exemplary embodiment, the two memory banks 10 are also constructed essentially in the same way, so that the two memory banks 10 can be regarded as voltage sources or current sources of the same type.

Furthermore, the high-voltage energy store 6 has a DC charging input 16, via which the high-voltage energy store 6 can be charged using direct current. The DC charging input 16 is added by a basic switching device 18, which is set up to enable at least two switching states, namely a first switching state and a second switching state. The basic switching device 18 is set up in such a way that in the first switching state the two memory banks 10 and the DC charging input 16 are connected in parallel and that in the second switching state the two memory banks 10 and the DC charging input 16 are connected in series . In this way, the high-voltage energy store 6 can be charged via one and the same DC charging input 16 with two different DC voltages as charging voltages. In the exemplary embodiment, these are 400 V and 800 VD, which means that the nominal voltage for both memory banks 10 is 400 V in the exemplary embodiment.

The high-voltage energy store 6 is also part of an on-board network 20 of the motor vehicle 2 and is also used in the on-board network 20 to supply a number of high-voltage consumers 22 in a sub-board network 24. The sub-board network 24 is not directly connected to the high-voltage energy store 6, but indirectly via an additional module 26. In the exemplary embodiment, the additional module 26 also has a housing 28, which closes off the additional module 26 from the outside.

Part of the additional module 26 is an additional switching device 30, which 2 is shown in more detail. That additional switching device 30 is connected to the two memory banks 10 via an intermediate tap 32 between the two memory banks 10 and the basic switching device 18. The intermediate tap 32 of the additional switching device 30 then carries the terminals 12 present on the memory banks 10 Voltages to independent of the switching state of the basic switching device 18.

The additional switching device 30 also has a supply output 34 for supplying the high-voltage consumers 22 in the vehicle electrical system section 24 with direct voltage. Furthermore, the additional switching device 30 is set up to enable at least two switching states, namely a first switching state and a second switching state. In this case, the two memory banks 10 and the supply output 34 are connected in parallel in the first switching state, and the two memory banks 10 and the supply output 34 are connected in series in the second switching state.

In the embodiment according to 2 the additional switching device 30 is further designed as a simple switching device. It has three semiconductor switches S1, S2, S3, which are formed, for example, by IGBTs (IGBT: insulated-gate bipolar transistor). With the aid of these semiconductor switches S1, S2, S3, it is only possible to connect the memory banks 10 so that they can be used as two voltage sources or two current sources either in a parallel connection or in a serial connection for the supply output 34. The switches S2 and S3 are closed and the switch S1 is open in the first switching state and the switches S2 and S3 are open and the switch S1 is closed in the second switching state. A third switching state is preferably additionally made possible, in which the supply output 34 is separated from the memory banks 10. This third switching state is in 2 shown. Here all three switches S1, S2, S3 are open.

The on-board electrical system 20 is then set up by the additional switching device 30 to optionally provide two different DC voltages as supply voltages at the supply output 34 for the supply of the high-voltage consumers 22 . This means that a first supply voltage is provided at the supply output 34 with the first switching state and that a second supply voltage is provided at the supply output 34 with the second switching state. In the exemplary embodiment, the first supply voltage is 400 V and the second supply voltage is 800 V. Switching between the first and the second switching state then requires switching between 400 V and 800 V. The exact supply voltages here usually vary depending on the state of charge of the High-voltage energy store 6 and/or depending on the state of use of the high-voltage energy store 6.

In addition, the additional module 26 in the exemplary embodiment has an AC charging input 36 for charging the high-voltage energy store 6 using AC voltage. The AC charging input 36 is connected to the two memory banks 10 via the additional switching device 30 and via the intermediate tap 32 . In this case, a rectifier circuit 28 is interposed between the AC charging input 36 and the additional switching device 30 for converting AC voltage into DC voltage. Depending on the design variant, the AC voltage is present as a single-phase AC voltage or as a multi-phase AC voltage.

In the exemplary embodiment, the high-voltage energy store 6 and the additional module 26 are also connected to one another via one or two cables that are not shown in detail. The high-voltage energy store 6 has two module outputs 40 and the additional module 26 has two module inputs 42. Each module output 40 is connected to exactly one memory bank 10, and vice versa, a module output 40 is provided for each memory bank 10 see. Each connection between memory bank 10 and module output 40 is preferably secured, for example via a safety fuse. Finally, each module output 40 is connected to a module input 42 .

Reference List

2

motor vehicle

4

E-motor supply output

6

High-voltage energy storage

8th

Housing

10

memory bank

12

connection pole

14

accumulator cell

16

DC charging input

18

Basic switching device

20

electrical system

22

high-voltage consumers

24

sub-network

26

add-on module

28

Housing

30

additional switching device

32

intermediate tap

34

supply output

36

AC charging input

38

rectifier circuit

40

module output

42

module input

S1

semiconductor switch 1

S2

semiconductor switch 2

S3

semiconductor switch 3

Claims (9)

Vehicle electrical system (20) for a motor vehicle (2) having a high-voltage energy store (6) with two memory banks (10), wherein - This has a DC charging input (16) for charging the high-voltage energy store (6) and a basic switching device (18), - the base switching device (18) is set up to enable two switching states, namely a first switching state in which the two memory banks (10) and the DC charging input (16) are connected in parallel, and a second switching state in which the two memory banks (10) and the DC charging input (16) are connected in series, - the two memory banks (10) are connected to an additional switching device (30), - the additional switching device (30) has a supply output (34) for supplying a number of high-voltage consumers (22) and - The additional switching device (30) is set up to enable two switching states, namely a first switching state in which the two memory banks (10) and the supply output (34) are connected in parallel, and a second switching state in which the two Memory banks (10) and the supply output (34) are connected in series. Electrical system (20) after claim 1 , wherein this is set up such that with the first switching state a first supply voltage is provided at the supply output (34), which is in the range between 300 V and 500 V, and that with the second switching state a second supply voltage at the supply output (34) is provided, which ranges between 700V and 900V. Electrical system (20) after claim 1 or 2 , wherein the high-voltage energy store (6) is designed as a module and wherein the additional switching device (30) is part of an additional module (26). Electrical system (20) after claim 1 or 2 , wherein the high-voltage energy store (6) is designed as a module and wherein the additional switching device (30) is part of this module. Electrical system (20) according to one of Claims 1 until 4 , wherein the high-voltage energy store (6) is designed as a module and wherein the base switching device (18) is part of this module. Electrical system (20) according to one of Claims 1 until 5 , wherein the additional switching device (30) is connected to the two memory banks (10) via an intermediate tap (32) between the two memory banks (10) and the basic switching device (18). Electrical system (20) according to one of Claims 1 until 6 , wherein this has an AC charging input (36) for charging the high-voltage energy storage device (6) and wherein the AC charging input (36) is connected to the two storage banks (10) via the additional switching device (30). is. Electrical system (20) according to one of Claims 1 until 7 , wherein this is set up in such a way that a charging operation is made possible in which the high-voltage energy store (6) is charged, and that in this charging operation at the supply output (34) a supply voltage is provided to supply the number of high-voltage consumers ( 22). Motor vehicle (2) having an on-board network (20) according to one of the preceding claims and designed as an electric vehicle (2) or hybrid vehicle.

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