DE102022210652A1 - Battery arrangement - Google Patents

Abstract

The present invention relates to a battery arrangement (1), in particular for a vehicle (100), comprising a first battery (2), wherein both poles (3, 4) of the first battery (2) are connected to an output (5), wherein a first pole (3) of the first battery (2) is connected to the output (5) by means of a galvanically isolating first switch (6) and wherein a second pole (4) of the first battery (2) is connected to the output (5) by means of a first bidirectionally blocking semiconductor switch arrangement (7); at least one second battery (8) which is connected in parallel to the first battery (2) and to the output (5), wherein, in particular for each second battery (8), a galvanically isolating second switch (9) is connected between the output (5) and a first pole (10) of the second battery (8) and a second bidirectionally blocking semiconductor switch arrangement (11) is connected between the output (5) and a second pole (12) of the second battery (8).

Description

State of the art

The present invention relates to a battery arrangement, in particular for a vehicle.

Electric vehicles, especially larger electric vehicles such as trucks, traditionally use several battery packs that are connected in parallel to increase the range. The parallel connection of the several battery packs is traditionally done using electromechanical switches, especially relays. However, such a parallel connection is problematic in that possible voltage differences between the individual battery packs and/or between the battery packs and a charging network or a load cause high currents in the electromechanical switches. Even small voltage differences cause high current peaks when switching between batteries with slightly different charge states. These high current peaks cause premature and severe aging of the electromechanical switches.

Out of JP 2014-124043 A a motor drive control device with a serial-parallel connection circuit is known. The connection circuit has a serial switch and two parallel switches and at least one of two step-up choppers. That is, this circuit has one or both step-up choppers. Each of the step-up choppers includes a reactor and an energy storage switch. The step-up chopper further includes an output switch which consists of the parallel switch of the connection circuit. This output switch is connected in series with the parallel switch and outputs a step-up voltage. The step-up chopper reduces current of the serial switch. The step-up chopper outputs a voltage value which is greater than a sum of the voltages of two DC power supplies.

Disclosure of the invention

A battery arrangement according to the invention has a first battery and at least one second battery. Both poles of the first battery are connected to an output. A first pole of the first battery is connected to the output by means of a galvanically isolating first switch. A second pole of the first battery is connected to the output by means of a first bidirectionally blocking semiconductor switch arrangement. The at least one second battery is connected in parallel to the first battery and to the output. A galvanically isolating second switch is connected between the output and a first pole of the second battery. A second bidirectionally blocking semiconductor switch arrangement is connected between the output and a second pole of the second battery.

By providing the combination of galvanically isolating switches in a first pole and the bidirectional blocking semiconductor switch arrangement at a second pole of the batteries, potential differences, which arise in particular due to different charge states of the batteries, can be compensated without high currents flowing.

The subclaims show preferred developments of the invention.

A connection arrangement of the second battery was explained above, according to which a galvanically isolating second switch is connected to a first pole of the second battery and a bidirectionally blocking semiconductor switch arrangement is connected to a second pole of the second battery. These switches are connected between the respective poles of the respective battery explained above and the output. However, the present invention is not limited to a total of two batteries. Rather, the battery arrangement preferably comprises a plurality of second batteries. Each of these second batteries preferably has a first pole and a second pole, the first pole of each of these second batteries being connected to the output by means of a galvanically isolating first switch and the second pole of each of these second batteries being connected to the output by means of a bidirectionally blocking semiconductor switch arrangement. In addition, each further second battery is preferably connected in parallel to the first battery and to the output.

Preferably, the first and/or the second bidirectional blocking semiconductor switch arrangement has at least two third switches and at least two diodes connected anti-serially to one another. At least one of the third switches is a semiconductor component. Preferably, all third switches are each semiconductor components.

In a special design, the third switches are transistors. These enable fast switching. The diodes are each connected anti-parallel with a transistor.

Preferably, the transistors are also connected anti-serially (bidirectionally blocking). Preferably, the transistors are connected to each other in a common drain (English: “common- drain”) or in a common source (English: “common-source”) arrangement.

The anti-parallel diodes are preferably intrinsic or extrinsic to the respective transistor. In an exemplary case in which the respective transistor is a unipolar transistor such as a MOSFET, the respective anti-parallel diode is an intrinsic diode of the transistor, for example the MOSFET. The intrinsic diode of the transistor is in particular a body diode of the transistor. Alternatively or additionally, in an exemplary case in which the respective transistor is a bipolar transistor such as an IGBT, the anti-parallel diode is preferably an element separate from the transistor.

Preferably, the first switch and/or the second switch are each a relay or a contactor. This allows a reliable galvanic isolating interruption to be created.

Preferably, the output is connected to a load and/or a power grid, in particular an on-board network and/or a charging network. The load is in particular an electrical machine of the vehicle. The on-board network is in particular an on-board network of the vehicle. The charging network is in particular a charging station for charging the vehicle, in particular by means of the on-board network of the vehicle.

In a preferred embodiment, the battery arrangement has a control unit for controlling a charging process and/or a discharging process of the batteries. The control unit is designed to control the switches and the bidirectionally blocking semiconductor switch arrangements for compensating voltage differences between the batteries.

Preferably, the control unit is configured to close the first switch and the third switches of the first semiconductor switch arrangement, while the second switch and the third switches of the second semiconductor switch arrangement are at least initially open. The second switch and the third switches of the second semiconductor switch arrangement are open in particular until a voltage difference between the first battery and the output is equalized.

“Open” preferably means that the corresponding switch is non-conductive. “Closed” preferably means that the corresponding switch is conductive.

By means of the second switch and the bidirectionally blocking semiconductor switch arrangement on the second battery, it can be ensured that, when the first switch is closed and when the third switches of the first semiconductor switch arrangement on the first battery are closed, a potential between the first battery and the output can be balanced without a charging current and/or a discharging current flowing from and/or to the second battery.

Preferably, the control unit is configured to close the second switch and one of the third switches of the second semiconductor switch arrangement, in particular during or after the equalization between the first battery and the output. In particular, a third switch of the second semiconductor switch arrangement is not closed or is kept open. In other words, in particular, only a third switch of the second semiconductor switch arrangement is closed.

Because one of the third switches of the second semiconductor switch arrangement is closed and the other switch is open, a current can flow through the closed third switch and through one of the diodes. The current from and/or to the second battery only flows through the diode when there is a potential difference between the second battery and the output and/or between the second battery and the first battery. Because the current flows through the diode even at very small potential differences, a strong and sudden increase in current can be prevented compared to conventional relay circuits. The diode explained above, through which the current flows, is the diode that is connected anti-parallel to the open third switch.

Preferably, the control unit is configured to close another of the third switches of the second semiconductor switch arrangement depending on a current flow through one of the diodes of the second semiconductor switch arrangement. In this case, the control unit is configured in particular to close the third switch of the second semiconductor switch arrangement via whose anti-parallel connected diode the above-mentioned current flows (when the other third switch of the same semiconductor switch arrangement is closed). This makes it possible to first prevent current peaks via the current flowing through said diode and then to close the corresponding third switch in order to reduce line losses.

Particularly preferably, the battery arrangement further comprises a charge state detection unit for detecting a charge state of the batteries. The control unit is designed to compare charge states of the batteries. During a discharge process of the batteries, the The control unit prefers the battery with the highest charge level as the first battery. Alternatively or additionally, the control unit is configured to set the battery with the lowest charge level as the first battery during a charging process of the batteries.

In other words, due to the parallel arrangement of all batteries, the above designations “first battery” and “second battery” are initially arbitrary and can refer to any of the plurality of batteries. By detecting the charge level of the batteries, the control unit then determines which of the batteries is/are “the first battery” or “the second battery” or “the second batteries”. In still other words, the control unit is set up, for example during a discharging process of the batteries, to first close the first switch and the third switches of the battery which has the highest charge level. Analogously, the control unit is set up, for example during a charging process of the batteries, to first close the first switch and the third switches of the battery which has the lowest charge level.

Preferably, in the case of a plurality of second batteries, the additional second batteries are sorted by the control unit according to their state of charge and the procedure explained above when charging or discharging the batteries is extended or repeated accordingly.

For example, the battery arrangement preferably has three batteries, i.e. two “second batteries”. The batteries are sorted by the control unit according to their charge levels. In the exemplary case of the discharge process, the battery with the highest charge level of the three batteries is defined as “the first battery”, the one with the second highest charge level is defined as “the second battery” and the one with the lowest or third highest charge level is defined as “the third battery” or as “another second battery”. At the start of the discharge process, as explained above, the control unit first closes the first switch and the third switches of the first semiconductor switch arrangement, which are connected to the first battery. After equalizing the potential of the first battery, the control unit closes the second switch and one of the third switches of the second semiconductor switch arrangement, which are connected to the second battery. As soon as or shortly after a current flows through one of the diodes of the second semiconductor switch arrangement, the second third switch of the second semiconductor switch arrangement is closed in order to reduce line losses. Then, analogously to the steps for the first battery and the second battery, the galvanically isolating switch, which is connected between the first pole of the third battery and the output, and a third switch of a further semiconductor switch arrangement, which is connected between the second pole of the third battery and the output, are closed. As soon as a current flows through the diode of the further semiconductor switch arrangement, the further third switch of the further semiconductor switch arrangement is then closed.

The charging and/or discharging process mentioned above can thus be extended or adapted to any number of batteries.

In the preferred embodiments explained above, preferably no further switches are connected between the above-mentioned elements. For example, no switches other than the first galvanically isolating switch are connected between the first pole of the first battery and the output. This preferably applies to all poles and/or all batteries.

The control unit is preferably a CPU and/or a GPU. The control unit is in particular an on-board computer of a vehicle.

Short description of the drawings

• 1 zeigt ein Schaltdiagramm einer Batterie-Anordnung gemäß einem ersten Ausführungsbeispiel der Erfindung,
• 2 zeigt ein Blockschaltdiagramm eines Verfahrens zur Steuerung der Batterie-Anordnung gemäß der ersten Ausführungsform,
• 3 zeigt ein Schaltdiagramm einer Batterie-Anordnung gemäß einem zweiten Ausführungsbeispiel der Erfindung, und
• 4 zeigt eine schematische Ansicht eines Fahrzeugs, welches die Batterie-Anordnung gemäß einem der Ausführungsbeispiele aufweist.

Embodiments of the invention are described in detail below with reference to the accompanying drawing. In the drawing:

• 1 shows a circuit diagram of a battery arrangement according to a first embodiment of the invention,
• 2 shows a block diagram of a method for controlling the battery arrangement according to the first embodiment,
• 3 shows a circuit diagram of a battery arrangement according to a second embodiment of the invention, and
• 4 shows a schematic view of a vehicle having the battery arrangement according to one of the embodiments.

Embodiments of the invention

1 shows a battery arrangement 1 according to a first embodiment of the invention. The battery arrangement 1 has a first battery 2 and a second battery 8. The first battery 2 has two poles 3, 4, which are each connected to an output 5. The output 5 is connected, for example, to a load. The A load is, for example, an electrical machine of a vehicle, in particular an inverter.

Alternatively or additionally, the output 5 is a power network, such as an on-board network of a vehicle and/or a charging network for an electric vehicle having the battery arrangement 1.

The first pole 3 of the first battery 2 is connected to the output 5 by means of a galvanically isolating first switch 6. The galvanically isolating first switch 6 is a relay. The second pole 4 of the first battery 2 is connected to the output 5 by means of a first bidirectional blocking semiconductor switch arrangement 7.

The second battery 8 also has two poles 10, 12. The second battery 8 is connected in parallel between the first battery 2 and the output 5. A first pole 10 of the second battery 8 is connected to the output 5 by means of a second galvanically isolating switch 9.

A second pole 12 of the second battery 8 is connected to the output 5 by means of a second bidirectional blocking semiconductor switch arrangement 11.

Both semiconductor switch arrangements 7, 11 each have two third switches 13, 14 and two diodes 15, 16 connected anti-serially to one another. The third switches 13, 14 are MOSFETs in this embodiment. The anti-serially connected diodes 15, 16 are intrinsic diodes of the MOSFETs, also called body diodes.

Due to the anti-serial arrangement of the diodes 15, 16, each semiconductor switch arrangement 7, 11 blocks a current from the respective battery 2, 8 to the output 5 and from the output 5 to the respective battery 2, 8, i.e. in both directions (“bidirectional”), when the transistors 13, 14 are in an open state (non-conductive state).

Furthermore, the battery arrangement 1 comprises a control unit 20 which controls the switches 6, 9 and the bidirectional blocking semiconductor switch arrangements 7, 11.

This arrangement of the connections of the batteries 2, 8 with each other and with the output 5 makes it possible to compensate for voltage differences between the batteries 2, 8, which will be explained below in conjunction with the 2 The voltage differences between the batteries 2, 8 arise from different charge states of the batteries 2, 8.

2 shows a block diagram of a method for controlling the battery arrangement 1 according to the first embodiment. 2 The method shown and explained below is carried out in particular by the control unit 20.

In the following, it is initially assumed that the batteries 2, 8 are discharged. In other words, the output 5 for the following explanation is a load, for example an electrical machine.

Furthermore, it is assumed below that in the present case the first battery 2 can deliver a higher output voltage than the second battery 8. In other words, it is assumed below that the state of charge of the first battery 2 is higher than the state of charge of the second battery 8.

First, in a first step S1, the first switch 6 between the first pole and the output 5 is closed. In a second step S2, the two third switches 13, 14 of the first bidirectional blocking semiconductor switch arrangement 7 are closed, i.e., switched to the conductive state. The steps S1 and S2 can in particular be carried out simultaneously or shortly after one another.

This compensates for a potential difference between the first battery 2 and the output 5.

After equalizing this potential difference, the second switch 9 between the output 5 and the first pole 10 of the second battery 8 is closed in a third step S3. At the same time or shortly thereafter, a third switch 13 of the second bidirectional blocking semiconductor switch arrangement 11 is closed in a fourth step. More precisely, when discharging the batteries 2, 8 in this step S3, the pole-side transistor 13 (left in 1 ) is closed. The other third switch 14 is initially not closed in this step.

As a result, the second battery 8 is connected in parallel to the first battery 2 and the output 5 by means of the closed second switch 9 and by means of the closed transistor 13 as well as by means of the diode 16. However, initially no current will flow from the battery 2 to the output 5 as long as the charge state (provided voltage) of the first battery 2 does not fall equal to or below the charge state (provided voltage) of the second battery 8. In other words, a current only flows through the diode 16 if there is a potential difference between the second battery 8 and the output 5 or the first battery 2.

If the charge level of the first battery 2 drops to such an extent that a potential difference arises between the second battery 8 and the output 5, a current flows from the second battery 8 via the third switch 13 and via the diode 16 to the output 5. This is also referred to as a "natural connection" of the batteries 2, 8. This makes it possible in particular for a current to flow from the second battery 8 as soon as the charge level of the first battery 2 drops sufficiently, without voltages having to be monitored or switching transitions having to be carried out with high currents.

Subsequently, in a fifth step S5, the second third switch 14 is also activated or closed in order to reduce conduction losses through the diode 16.

Because activation of diode 16 does not occur suddenly, in contrast to closing a galvanically isolating switch (e.g. a relay), high current peaks can be avoided even with small potential differences.

Overall, the batteries 2, 8 can be connected more efficiently and safely by means of the connection arrangement of the battery arrangement 1 explained above.

The connection arrangement of the battery arrangement 1 explained above is advantageous not only for a discharging process, but also for a charging process.

For this purpose, it is assumed below that the state of charge of the first battery 2 is lower than the state of charge of the second battery 8. In other words, it is assumed below that the voltage provided by the first battery 2 is lower than the voltage provided by the second battery 8.

Again 2 As can be seen, the steps S1 to S3 are essentially carried out in the same way as for the discharge process. In a first step S1, the first switch 6 between the first pole 3 of the first battery 2 and the output 5 is closed. In a second step S2, the transistors 13, 14 between the second pole 4 of the first battery 2 and the output 5 are closed. In a third step, the second switch 9 between the first pole 10 of the second battery 8 and the output 5 is closed.

In a sixth step S6, in contrast to the step S4 explained above, only the output-side transistor 14 (right in 1 ) is closed. During the charging process, the current flows via the diode 15 (pole-side diode 15) to the second pole 12 of the second battery 8.

In a seventh step S7, the other third transistor 13 is then closed, similar to the fifth step S5, in order to avoid conduction losses through the diode 15.

The charging and discharging processes explained above can in particular be carried out one after the other.

In order to carry out the charging and discharging processes explained above, the control unit is particularly designed to detect a charge state of the batteries 2, 8. This can be done, for example, by detecting the voltage provided by the batteries 2, 8.

3 shows a schematic circuit diagram of a battery arrangement 1 according to a second embodiment.

Again 3 As can be seen, the battery arrangement 1 can have a plurality of second batteries 8. Each second battery 8 is connected in parallel to the first battery 2 and the output 5 as well as all other second batteries 8.

Furthermore, a first pole 10 of each (further) second battery 8 is connected to the output 5 via a second galvanically isolating switch 9. Each second pole 12 of each (further) second battery 8 is connected to the output 5 by means of a second bidirectional blocking semiconductor switch arrangement 11.

In this case, the above-mentioned steps S1 - S5 and/or S1 - S3 and S6, S7 are repeated accordingly for the discharging process and/or the charging process. More precisely, the steps S3 - S5 and/or the steps S3, S6, S7 are repeated for each (further) second battery 8.

4 shows a schematic view of a vehicle 100 comprising the battery assembly 1 according to one of the embodiments of the present invention.

The control unit 20 is preferably an on-board computer of the vehicle 100.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was 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 accepts no liability for any errors or omissions.

Cited patent literature

• JP 2014124043 A [0003]

Claims (10)

Battery arrangement (1), in particular for a vehicle (100), comprising: a first battery (2), wherein both poles (3, 4) of the first battery (2) are connected to an output (5), wherein a first pole (3) of the first battery (2) is connected to the output (5) by means of a galvanically isolating first switch (6) and wherein a second pole (4) of the first battery (2) is connected to the output (5) by means of a first bidirectionally blocking semiconductor switch arrangement (7); at least one second battery (8) which is connected in parallel to the first battery (2) and to the output (5), wherein, in particular for each second battery (8), a galvanically isolating second switch (9) is connected between the output (5) and a first pole (10) of the second battery (8) and a second bidirectionally blocking semiconductor switch arrangement (11) is connected between the output (5) and a second pole (12) of the second battery (8). Battery arrangement (1) according to Claim 1 , wherein the first and/or the second bidirectional-blocking semiconductor switch arrangement (7, 11) has at least two third switches (13, 14) and at least two diodes (15, 16) connected anti-serially to one another, wherein at least one of the third switches (13, 14), in particular all third switches (13, 14), are semiconductor components. Battery arrangement (1) according to Claim 2 , wherein the third switches (13, 14) are transistors and wherein the diodes (15, 16) are each connected anti-parallel with a transistor (13, 14). Battery arrangement (1) according to one of the preceding claims, wherein the first switch (6) and/or the second switch (9) is a relay and/or a contactor. Battery arrangement (1) according to one of the preceding claims, wherein the output (5) is connected to a load and/or a power network, in particular an on-board network and/or a charging network. Battery arrangement (1) according to one of the Claims 2 until 5 , comprising a control unit (20) for controlling a charging process and/or a discharging process of the batteries (2, 8), wherein the control unit (20) is configured to control the switches (6, 9) and the bidirectionally blocking semiconductor switch arrangements (7, 11) for compensating voltage differences between the batteries (2, 8). Battery arrangement (1) according to Claim 6 , wherein the control unit (20) is configured to close the first switch (6) and the third switches (13, 14) of the first semiconductor switch arrangement (7), while the second switch (9) and the third switches (13, 14) of the second semiconductor switch arrangement (11) are at least initially open, in particular are open until a voltage difference between the first battery (2) and the output (5) is equalized. Battery arrangement (1) according to Claim 7 , wherein the control unit (20) is arranged, in particular during or after the equalization between the first battery (2) and the output (5), to close the second switch (9) and one of the third switches (13, 14) of the second semiconductor switch arrangement (11). Battery arrangement (1) according to Claim 8 , wherein the control unit (20) is configured to close a further one of the third switches (13, 14) of the second semiconductor switch arrangement (11) as a function of a current flow through one of the diodes (14, 15) of the second semiconductor switch arrangement (11). Battery arrangement (1) according to one of the Claims 7 until 9 , further comprising a charge state detection unit for detecting a charge state of the batteries (2, 8), wherein the control unit (20) is configured to compare charge states of the batteries (2, 8) and, during a discharging process of the batteries (2, 8), to set the battery with a highest charge state as the first battery (2), and/or during a charging process of the batteries (2, 8), to set the battery with a lowest charge state as the first battery (2).

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