DE102016010839A1 - High-voltage battery system for a motor vehicle and method for producing a plurality of operating states - Google Patents

Abstract

The object of the present invention is to compensate for charge differences between two energy stores (16, 18). The invention relates to a high-voltage battery system (10) for a motor vehicle, which is at least partially electrically operable, with at least two energy stores (16, 18) which can be connected in series and in parallel, and wherein a plurality of operating states of the high-voltage battery system (10) can be produced in which the high-voltage battery system (10) has an on-board charger (32) for at least two separate output voltages (U1, U2), each of the output voltages (U1, U2) being provided for each of the at least two energy stores (16, 18), wherein the on-board charger (32) of at least one of the operating states of the high-voltage battery system (10) can be produced.

Description

The invention relates to a high-voltage battery system for a motor vehicle according to the preamble of patent claim 1 and to a method for producing a plurality of operating states in a high-voltage battery system according to patent claim 7.

High-voltage battery systems with at least two energy stores are already known from the prior art. The US 2015/0002095 A1 describes an electrical storage system having a plurality of DC buses and a plurality of energy storage devices, which are connected in series and are suitable for charging and discharging. The number of DC buses is greater than the number of energy storage. The energy storage devices have a respective switch, which is connected in series with the energy store. Furthermore, the switches are interconnected with the DC buses and can switch between the DC buses by means of the switch. The energy of the energy storage can be directed to a consumer point. Furthermore, a voltage detector is disclosed which detects a voltage of the respective energy store. A control unit switches the switches according to a detected voltage of the voltage detector.

Object of the present invention is to develop a high-voltage battery system of the type mentioned in such a way that charge differences between the at least two energy storage can be compensated.

This object is made possible by a high-voltage battery system having the features of patent claim 1 and by a method for producing a plurality of operating states according to patent claim 7.

Advantageous embodiments with expedient developments of the invention are specified in the remaining claims.

In order to develop a high-voltage battery system in the preamble of claim 1 and a method specified in the preamble of claim 7 such that charge differences between the at least two energy storage can be compensated, it is inventively provided that the high-voltage battery system has an on-board charger for at least two separate output voltages of which each of the output voltages is provided in each case for one of the at least two energy stores, wherein at least one of the operating states of the high-voltage battery system can be produced by means of the on-board charger. In the high voltage battery system, the sub-strings may be charged differently and have different voltages. The consequence would be uncontrollable balancing currents, which would lead to energy losses (heat), aging of the components or even destruction of the components. In particular relays would be particularly affected by the uncontrollable balancing currents. The resulting over time imbalance of the charge states or the voltages of the at least two energy storage devices can be compensated according to the invention via the on-board charger, which may be in particular two-phase. The recharging current can be regulated at any time. A galvanic separation of the two sub-networks is guaranteed at all times. Thus, recharge currents for battery balancing can be controlled at any time and, if necessary, also stopped. It is furthermore advantageous that an additional expenditure due to the on-board loader does not arise since the on-board loader, as already known from the prior art, has already been developed as a two-phase supercharger for at least two separate output voltages.

By means of the high-voltage battery system according to the invention can be dispensed with complicated interconnections, for example, the electric motor. For example, an electric motor with more than one three-phase system is currently used to equalize the currents (for example, two separate three-phase systems). These are operated by separate inverters and can be connected both in the star and in the delta. Also a combination of star / triangle is possible. The DC voltage supply of the inverter takes place via partial taps of the high-voltage battery system. Thus, for example, in an 800 volt battery system and a 2 x 3 phase motor, one inverter may be supplied with the lower 400 volt (0 to 400 volt) and the other with the upper 400 volt (400 to 800 volt). Thus, each semiconductor with a lower blocking resistance can be used against operation at 800 volts. Via the stator of the motor, the energy can be transferred from one voltage level to the other. By choosing the turns ratio between the two three-phase systems and the circuit type (star / delta), the total voltage can also be split in a different ratio. However, this has the disadvantage that the electric motor must be constructed very complicated or that in case of a defect, the entire electric motor must be replaced, which can lead to increased costs.

According to an advantageous embodiment of the high-voltage battery system, the high-voltage battery system on exactly two energy storage and a on-board charger with exactly two output voltages. This has the advantage that in current high-voltage battery systems in motor vehicles this each loaded with different operating conditions or an operating state, for example, the driving is. By means of the exactly two energy stores, it is possible, for example, that charging can be carried out with a higher voltage, it being possible to divide the voltages between the individual energy stores. Thus, it makes sense that the on-board charger also has exactly two output voltages for the respective energy storage.

According to a further advantageous embodiment, the two energy stores can be electrically coupled to each other by means of exactly one switch. By means of exactly one switch, a series connection of exactly two energy storage is possible, whereby a further operating state of the entire high-voltage battery system can be produced.

In a further advantageous embodiment, respective terminals can be provided, via which the at least two energy stores can be charged with a DC voltage or with an AC voltage. This has the advantage that several options for charging the at least two energy stores can be provided. For example, can be charged with a DC voltage from a Aufladesäule the at least two energy storage or is also a charge from a household standard AC power outlet possible.

In a further advantageous embodiment, further respective connections are provided, via which the at least two energy stores can be charged with at least two DC voltages which are different in voltage. It has been found that, for example, energy stores in motor vehicles have a voltage of 400 volts each. By providing the further connections, charging with 800 volts (double voltage of the energy storage devices) can be provided, for example. This has the advantage that the high-voltage battery system can be charged faster. Thus, a further operating state can be provided via the high-voltage battery system according to the invention. This increases the flexibility during the charging process.

It has also proved to be advantageous if at least one of the plurality of operating states is a driving operation and at least one of the plurality of operating states is a charging operation. In particular, it can be three charging stations. In the different operating conditions, it may happen that differences in charge between the two energy storage must occur and must be compensated. For example, when switching from an 800-volt charging mode (two energy storage devices of the high-voltage battery system connected in series) to the 400-volt driving mode (energy storage devices are connected in parallel), the energy stores can be charged differently and have different voltages. Uncontrollable equalizing currents would be the result, which would lead to energy losses (heat), aging of the components or even to the destruction of the components. The imbalances that arise over time in the majority of operating states can be compensated. In particular, the operating states may be an 800-volt DC charging or a 400-volt DC charging, or a 400-AC charging or a driving operation.

The invention also relates to a method for producing a plurality of operating states in a high-voltage battery system having at least two battery stores of a motor vehicle which is operated at least partially electrically, wherein at least two separate output voltages are generated by means of an on-board charger which is coupled to the at least two energy stores, so that at least one of the plurality of operating conditions is established.

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

Showing:

1 a schematic representation of an embodiment of a high-voltage battery system according to the invention;

2 the high-voltage battery system according to the invention in a first operating state;

3 the high-voltage battery system according to the invention in a second operating state;

4 the high-voltage battery system according to the invention in a third operating state; and

5 the high-voltage battery system according to the invention in a fourth operating state.

In the figures, identical or functionally identical elements are provided with the same reference numerals.

1 shows an embodiment of a high-voltage battery system according to the invention 10 , The high-voltage battery system 10 can be a plurality of sub-strands 12 . 14 exhibit. In the in 1 illustrated embodiment, the high-voltage battery system 10 a first substrand 12 and a second sub-string 14 on. The substring 12 also has a first energy storage 16 on. The substring 14 has a second energy storage 18 on. Furthermore, the respective sub-strands 12 . 14 respective ancillaries 20 . 22 exhibit. At the ancillaries 20 . 22 they may in particular be consumers who, for example, do not directly serve to drive a motor vehicle, not shown. In particular, it can be provided that the ancillaries are operable with 400 volts. This has the technical background that built in the motor vehicle on-board networks usually work with a 400 volt voltage level. Furthermore, in this example, the first energy storage 16 as well as the second energy storage 18 a DC voltage of 400 volts ready. It goes without saying that the 400 Volt is just an example. This is merely illustrative of the invention. There are, of course, other voltage levels or voltages within the sub-strands 12 . 14 possible.

By means of the first energy storage 16 Thus, a first voltage U _{1 is} provided and by means of the second energy store 18 provided a second voltage U ₂ . The voltages U ₁ and U ₂ are also referred to as output voltages U ₁ , U ₂ . Furthermore, in the sub-strands 12 . 14 capacitors 24 . 26 or semiconductors are provided, whereby, for example, a control of an electric machine 28 . 30 can be carried out. It should be clarified here that in the high-voltage battery system 10 the second electric machine 30 or the second accessory 22 optional. It is also possible that in an inverse order the electric machine 28 or the first accessory 20 optional.

The respective partial strands 12 . 14 are with a on-board loader 32 connected. The on-board loader 32 again has a voltage transformer 34 which in particular has a filter for smoothing an AC voltage U _AC and a power correction factor. The voltage converter 34 can be fed in particular with the AC voltage U _AC . Furthermore, the on-board loader 32 a first DC / DC converter 36 and a second DC / DC converter 38 on. The two DC / DC converters 36 . 38 are constructed in particular insulating. Thus, the partial strands 12 . 14 from the on-board loader 32 galvanically isolated.

Furthermore, the high-voltage battery system 10 a plurality of connections 40 . 42 . 44 . 46 . 48 . 50 on, over which the energy storage 16 . 28 are rechargeable. For example, with a voltage U ₃ , which in particular corresponds to twice the voltage of U ₁ or U ₂ or the sum of the voltages U ₁ + U ₂ , the energy storage 16 . 18 getting charged. Furthermore, the in 1 illustrated high-voltage battery system 10 a switch 52 on, by means of which the two energy storage 16 . 18 can be connected in series.

2 shows that off 1 known high-voltage battery system 10 in a first operating state. The in 2 shown operating state can in this case in particular a loading of the energy storage 16 . 18 be with the charging voltage U ₃ . In particular, in the case of motor vehicles, this may be, for example, an 800 volt DC voltage. The desk 52 is closed. Thus, the energy storage 16 and 18 connected in series. For example, via the connectors 48 . 50 the voltage U ₃ in the high-voltage battery system 10 be fed. About the arrows 54 schematically the main charging current is shown. This flows from the connection 48 over the first energy storage 16 over the switch 52 over the second energy storage 18 towards the connection 50 , The voltage U ₃ corresponds in particular to the respective double voltages U ₁ or U ₂ or the sum of the individual voltages from U ₁ and U ₂ . Since the voltage U ₁ and the voltage U ₂ may be different, for example due to the aging of the first energy storage 16 or the second energy store 16 can via the on-board loader 32 equalizing currents 56 (also shown by arrows) flow. This is done by a magnetic power transmission 58 within the on-board loader 32 guaranteed. The equalizing currents 56 are also called balancing streams.

3 shows a further operating state of the high-voltage battery system according to the invention 10 , In this operating state is in particular a charging operation, by means of which with the AC voltage U _AC, the high-voltage battery system 10 is operated. About the AC power connections 51a Up to c can in particular the three-phase AC voltage U _AC in the on-board loader 32 be fed. The voltage converter 34 converts the AC voltage U _AC into a respective DC voltage provided by the first and second DC / DC converters 36 . 38 is converted into a respective output voltage. The respective Output voltage is via the first DC / DC converter 36 the arrows 54 the main charging current following the first energy storage 16 passed and loads the first energy storage 16 thus up. The same happens with the second DC / DC converter 38 and the second energy storage 16 , The desk 52 is in 3 open.

4 shows the high-voltage battery system 10 in a further operating state. Here is the high-voltage battery system 10 for example, charged with the voltage U ₂ . For example, this can be done at the terminals 46 . 48 the corresponding voltage U _{2 are} fed. In particular, this can be 400 volts DC. About the arrows 54 the main charging current is indicated. The main charging current flows when the switch is closed 52 for example, from the connection 46 over the second energy storage 18 and loads the second energy store 18 , From there he goes to the second port 48 , From the connection 46 can continue the voltage U ₂ via the second DC / DC converter 38 also for connection 48 reach. In the second DC / DC converter 38 can via the magnetic power transmission 58 Energy to the first DC / DC converter 36 be transferred so that this over the arrows 54 the main charging current, the first energy storage 16 can charge. In an analogous way, of course, the first sub-string 12 be connected and thus the second sub-string 14 getting charged.

5 shows the high-voltage battery system 10 in a further operating state. At the in 5 shown operating state is in particular the driving operation of a motor vehicle. When driving, especially the electrical machines 28 and 30 operated with the corresponding voltages U ₁ and U ₂ . Based on the substring 12 Now the driving is explained. Energy from the first energy store 16 will be provided. About the arrows 54 becomes the main charging current for the first electric machine 28 provided. It also gets electrical energy for the first accessory 20 provided. About the first DC / DC converter 36 can now equalizing currents 56 flow. These in turn will be by means of magnetic power transmission 58 to the second branch 14 issued. Thus it can be ensured that the stresses within the substrands 12 . 14 are almost the same and thus the life of the high-voltage battery system 10 can be extended.

By the high-voltage battery system according to the invention 10 Thus, it is possible to operate an 800-volt network with much fewer switches / contactors. Furthermore, uncontrollable equalizing currents can be avoided in 400-volt operation (driving, 400-volt DC charging, AC charging). The recharge currents for battery balancing can be controlled at any time and, if necessary, stopped. The result is two HV subsystems, each with 400 volts operating voltage. An insulating DC / DC converter from 800 volts to 400 volts is unnecessary, as it is currently installed in the prior art. There is no additional effort in the AC charger as the charger is already being developed as a two-phase charger. In the modes "driving mode", "400-volt DC charging" and "AC charging" are the energy storage 16 . 18 via a switch 52 separated. The resulting over time imbalance of the charge states or voltages of the two sub-strands 12 . 14 is about the on-board loader 32 , which in particular a two-phase on-board loader 32 can be balanced. A galvanic separation of the two partial strands 12 . 14 is guaranteed at any time. By a charge of, for example, 800 volts, an increased charging power can be performed. It is still possible to operate the system with 400 volts (infrastructure independence). Furthermore, apart from the charging components, there are no changes to the components of the high-voltage battery system 10 , in particular the electrical system, necessary. The contactor matrix to switch the strands of the battery depending on the use cases, is omitted in the present invention. This contactor matrix is only necessary in the event that is charged with 800 volts DC voltage. The electric potential separation, which is given by the contactor matrix, is eliminated in the high-voltage battery system according to the invention 10 , Thus, the potential-separating DC / DC converter can be saved.

LIST OF REFERENCE NUMBERS

10

High-voltage battery system

12

first substrand

14

second substrand

16

first energy store

18

second energy store

20

first accessory

22

second accessory

24

first capacitor

26

second capacitor

28

first electric machine

30

second electric machine

32

board charger

34

DC converter

36

first DC / DC converter

38

second DC / DC converter

40

connection

42

connection

44

connection

46

connection

48

connection

50

connection

51a

AC connection

51b

AC connection

51c

AC connection

52

switch

54

arrow

56

transient

58

magnetic power transmission

U ₁

first tension

U ₂

second tension

U ₃

third tension

U _AC

AC

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2015/0002095 A1 [0002]

Claims (7)

High voltage battery system ( 10 ) for a motor vehicle, which is at least partially electrically operable, with at least two energy stores ( 16 . 18 ), which are switchable in series and in parallel, and wherein a plurality of operating states of the high-voltage battery system ( 10 ), characterized in that the high-voltage battery system ( 10 ) an on-board loader ( 32 ) for at least two separate output voltages (U _{1 ,} U ₂ ), of which each of the output voltages (U ₁ , U ₂ ) in each case for one of the at least two energy stores ( 16 . 18 ), wherein by means of the on-board loader ( 32 ) at least one of the operating states of the high-voltage battery system ( 10 ) can be produced. High voltage battery system ( 10 ) according to claim 1, characterized in that the high-voltage battery system ( 10 ) exactly two energy stores ( 16 . 18 ) and a on-board loader ( 32 ) with exactly two output voltages (U _{1 ,} U ₂ ). High voltage battery system ( 10 ) according to claim 2, characterized in that the exactly two energy stores ( 16 . 18 ) by means of exactly one switch ( 52 ) are electrically coupled to each other. High voltage battery system ( 10 ) according to any preceding claim, characterized in that respective connections ( 40 . 42 . 44 . 46 . 48 . 50 ) are provided, via which the at least two energy stores ( 16 . 18 ) with a DC voltage (U ₁ , U ₂ , U ₃ ) or with an AC voltage (U _AC ) are rechargeable. High voltage battery system ( 10 ) according to any preceding claim, characterized in that further respective connections ( 40 . 42 . 44 . 46 . 48 . 50 ) are provided, via which the at least two energy stores ( 16 . 18 ) are chargeable with at least two different in the voltage DC voltages (U ₁ , U ₂ , U ₃ ). High voltage battery system ( 10 ) according to a preceding claim, characterized in that at least one of the plurality of operating states is a driving operation and at least one of the plurality of operating states is a charging operation. Method for producing a plurality of operating states in a high-voltage battery system ( 10 ) with at least two energy stores ( 16 . 18 ), a motor vehicle which is at least partially electrically operated, characterized in that by means of a on-board loader ( 32 ), which with the at least two energy stores ( 16 . 18 ), at least two separate output voltages (U _{1 ,} U ₂ ) are generated so that at least one of the plurality of operating states is established.

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