DE102019134213B4 - Energy storage for a vehicle - Google Patents

Abstract

Energy store (1) for an electrically drivable vehicle, with at least two parallel-connected storage strands (10, 20, 30, 40), wherein the energy store has a first interface (61) and a second interface (62), the first interface (61 ) is coupled to the storage strings (10, 20, 30, 40), wherein the energy storage device (1) comprises a DC-DC converter (71), wherein the second interface (62-64) is coupled to the DC-DC converter (71), the storage strings (10, 20, 30, 40) and the DC-DC converter (71) are arranged in a common housing (85), the energy store (1) having activatable safety isolating elements (P1, P2) and the activatable safety isolating elements (P1, P2) being set up To separate the first interface (61) from the storage strands (10, 20, 30, 40) at a defined event without interrupting the power supply at the second interface (62-64), thereby marked This means that the storage strings (10, 20, 30, 40) are high-voltage storage strings and each have at least one first and one second partial storage string (11, 12; 21, 22; 31, 32; 41, 42) with an intermediate center tap (13, 23, 33, 43), each partial storage string containing at least one high-voltage DC voltage source and the high-voltage direct voltage source having a potential difference of at least 60 volts, the first partial storage strings (11, 21, 31, 41) each have a switchable isolating element (14, 24, 34, 44) arranged in series, and two of the high-voltage storage strands (10, 20, 30, 40) each at the center taps (13, 23, 33, 43) can be electrically coupled via a switching element (51, 52, 53), the first interface (61) being a high-voltage interface for supplying energy to a high-voltage vehicle electrical system, the second interface (62-64) being a low-voltage interface for supplying energy to a low-voltage -On-board electrical system, the DC-DC converter (71) being a high-voltage/low-voltage DC-DC converter and being fed from one of the first partial storage strings (11, 21, 31, 41).

Description

The invention relates to an energy store for an electrically driven vehicle and an electrically driven vehicle.

Electrically driven vehicles are increasingly attracting people's interest. In particular, land vehicles, namely off-road and road vehicles such as passenger cars, buses, trucks and other commercial vehicles, rail vehicles (trains), but also watercraft (boats) and aircraft such as helicopters, multicopters, propeller aircraft, jet aircraft should be considered to be electrically powered vehicles, which at least have an electric motor used to propel the vehicle. Vehicles can be manned or unmanned. In addition to pure electric vehicles (BEV), the definition should also include hybrid electric vehicles (HEV), plug-in hybrids (PHEV) and fuel cell vehicles (FCHV).

The number of electrical safety, comfort and information systems is already considerable today, depending on the vehicle category and equipment. It can be observed that more and more components of this type are being installed. Examples include drive-by-wire systems (electric steering) and break-by-wire systems (electric braking), active chassis control for land vehicles, assistance systems and infotainment systems. There is a constant need to increase the storage capacity of the energy storage, the efficiency of the electrical components, the system availability and reliability, to shorten the charging time and to master the complexity in technology and production.

There have already been various technical approaches in the past to further develop the state of the art.

DE 10 2011 006 755 A1 relates to a system with a number of power supply branches connected in parallel, which are each connected via an output connection to one of a number of phase connections of an electrical power supply network. Each of the energy supply branches has at least two energy source modules connected in series, each with at least one photovoltaic module. The core idea is to connect photovoltaic modules in a matrix and to couple the photovoltaic modules into the energy supply lines in a coordinated manner via separate coupling devices assigned to the individual photovoltaic modules. In this way, it should be possible to generate three-phase current via suitable control of the coupling devices without the need for separate inverters.

In the DE 10 2010 009 260 A1 discloses a device for supplying a vehicle electrical system, in which converter channels which are electrically connected to the vehicle electrical system on the output side are each electrically connected on the input side to a storage element of an energy storage device composed of a plurality of these elements. A battery management unit BMU, which is electrically connected to the vehicle electrical system and to the storage elements of the energy store, controls or regulates the converter channels in such a way that the charge status of the storage elements is adjusted to one another through targeted charge removal and the voltage of the vehicle electrical system is kept constant at a target value.

US 2018/0 043 789 A1 discloses an electrical circuit with at least three battery modules. Each of the battery modules includes at least one battery part and at least two electrical switches. Each of the battery modules is electrically connected to at least a second battery module via an electrical connecting line.

US 2016/0 254 521 A1 describes a storage battery in which one or more pyrotechnic safety isolating elements (so-called pyrofuses) are provided.

In the DE 10 2013 204 073 A1 a battery is provided which includes a battery housing and two connections for a consumer. The battery also includes a battery string which is arranged in the battery housing and which connects the two connections to one another and has at least one battery cell which is connected in series and/or in parallel with the battery string. A thermal tripping element is arranged within the battery housing.

The triggering element is designed to trigger when a predetermined first temperature is present in the area of the thermal triggering element.

U.S. 8,842,404 B2 discloses a short-circuit protection device for limiting or switching off short-circuit currents in high-energy direct-current networks.

the DE 10 2016 213 844 A1 describes a battery system with a current interruption arrangement for separating an electrical current flow between at least one battery of the battery system and a consumer. The current interruption arrangement has a number of power semiconductors.

DE 10 2008 053 074 A1 shows a high-speed switching device for a high-performance battery in a submarine direct current network. The high-performance battery comprises a plurality of battery modules connected in parallel, each with at least one strand of high-performance battery cells connected in series. Each of the strands, which have the grid voltage of the DC island grid, has a switching unit for each of the battery modules. The switching unit comprises a parallel circuit made up of a diode polarized to let the charging current of the battery module through and a power semiconductor switch polarized to let the discharge current through. The parallel circuit is arranged in a connecting conductor of the battery module. The switching state of the power semiconductor switch can be controlled by a monitoring and control device in order to interrupt the discharge current flowing in the connecting conductor.

In the DE 10 2015 219 589 A1 describes a vehicle battery device with a first accumulator, which has an intermediate tap, a second accumulator, which has a positive pole, and with a first and a second positive terminal. The positive pole of the second battery is connected to the intermediate tap of the first battery. The second accumulator has a nominal voltage that is lower than the nominal voltage of the first accumulator. The first positive connection is connected to a positive pole of the first accumulator. The second positive connection is connected to the positive pole of the second accumulator. A ground connection of the vehicle battery device is connected to a negative pole of the first accumulator via a first switch. The ground connection is also connected to a negative pole of the second accumulator via a second switch. The vehicle device provides two low-voltage voltages.

None of the cited documents relates to an energy store for an electrically driven vehicle that meets the particularly high requirements for operational safety and reliability, particularly in connection with the assistance systems for autonomous driving.

It is therefore an object of the invention to provide an energy storage device for an electrically driven vehicle and a corresponding vehicle that is improved in relation to the points mentioned.

The object is achieved by an energy storage device according to claim 1. The energy storage device has at least two high-voltage storage strings connected in parallel, each with at least a first and a second partial storage string connected in series. The sub-storage strings each include at least one high-voltage direct voltage source. According to the disclosure, high-voltage direct currents are characterized by a potential difference of at least 60 volts. In the present case, the high-voltage direct current of the high-voltage storage strands can be several hundred volts, e.g. B. 200 V, 400 V, 600 V, 800 V, 1200 V or voltage values between the mentioned. For example, the partial storage strings can be battery modules each having a plurality of cells connected in series. A number of battery modules, possibly with additional electronic components, can also be combined to form a battery pack and form a partial storage string. The redundant supply from at least two high-voltage storage strings improves the availability and reliability of the energy supply.

According to a further aspect, the first partial storage strings each include a switchable isolating element arranged in series with the high-voltage DC voltage source. A current flow in the first sub-storage strings can be interrupted by the isolating element.

Furthermore, a center tap is arranged between the first and the second partial storage line. Two of the high-voltage storage strings can be electrically coupled at the center taps via a switching element. Due to the switchable coupling, the current flow in the energy store and in particular between the partial storage strings can be controlled (redirected) in a way that is adapted to the situation.

Preferred configurations of the invention are specified in the dependent claims and the following description, each of which individually or in combination can represent an aspect of the invention.

Advantageously, by selectively coupling at least two of the center taps, an active charge transfer/charge reversal can be carried out between the storage strings or the individual partial storage strings.

The energy store includes a high-voltage interface for supplying energy to a high-voltage vehicle electrical system and a low-voltage interface for supplying energy to a low-voltage vehicle electrical system. Low-voltage vehicle electrical systems are generally those that are not high-voltage vehicle electrical systems. Low-voltage vehicle electrical systems can have a voltage of 12 V, 24 V or 48 V, for example. The high-voltage interface can preferably be electrically coupled to the high-voltage storage strings. The energy store can include a high-voltage/low-voltage direct-current converter. The low-voltage interface can preferably be connected to the high-voltage Be coupled low-voltage DC-DC converter. The high-voltage/low-voltage direct current converter can in particular be fed from one of the first partial storage strings. The high-voltage vehicle electrical system can be a traction vehicle electrical system, which includes at least one traction motor and/or possibly other consumers. A separate low-voltage battery to supply the low-voltage vehicle electrical system is then no longer absolutely necessary. Optionally, an additional (low-capacity) voltage source can be provided for the system start-up.

According to one advantageous aspect, the second partial storage strings can each include a switchable isolating element connected in series. As a result, the flow of current in the second partial storage strings can be interrupted.

The switchable isolating elements can each include a semiconductor switch. Semiconductor switches hardly wear out. Furthermore, an active battery or cell management can be operated through a targeted control, for example with a pulse width modulation (PWM) or an operation in the pinch area. For example, voltage differences can be compensated for by controlled charge transfers.

Advantageously, the switchable isolating elements can have an electrically or electromagnetically actuatable switch connected in parallel or in series with the semiconductor switch. The parallel connection minimizes losses and increases availability if an isolating element fails. The alternative series connection can promote safe electrical separation. The switchable isolating elements can preferably include a safety isolating element or a fuse. The (additional) redundancy promotes safe separation of the current path.

According to a further advantageous aspect, the energy store can have a second high-voltage/low-voltage direct-current converter. The second high-voltage/low-voltage direct-current converter can be fed from one of the first or second partial storage strings. The low-voltage interface can be coupled to the second high-voltage/low-voltage direct-current converter.

The energy store can preferably have a further high-voltage/low-voltage direct-current converter. The additional high-voltage/low-voltage DC converter can be fed from one or more of the high-voltage storage strings.

The different high-voltage/low-voltage DC converters can each supply different (low-voltage) sub-networks. Alternatively, the high-voltage/low-voltage DC converters can increase redundancy.

According to a further advantageous aspect, the energy store can have at least three of the high-voltage storage strands. This configuration has proven to be particularly suitable.

Advantageously, the center taps can be coupled in a ring shape via the switching elements. The ring-shaped coupling increases the number of alternative current paths.

In an advantageous embodiment, the energy store can include four or more of the high-voltage storage strings.

According to a further advantageous aspect, one high-voltage storage string or two high-voltage storage strings can be arranged in a battery housing. In this way, the high-voltage storage strings can be removed from the energy store and serviced or replaced particularly easily.

According to a further aspect, the high-voltage storage strings and the high-voltage/low-voltage direct current converter(s) are arranged in a common housing. The energy store has safety isolating elements that can be activated. The safety isolating elements are set up to separate the high-voltage interface from the high-voltage storage strands in the event of a defined event, but without interrupting the energy supply at the low-voltage interface.

The safety isolating elements can be, for example, pyro switches (pyrofuses) and/or fuses. The safety isolating elements can be set up and arranged in the electrical circuit in order to separate the high-voltage interface from the high-voltage voltage sources in the event of a defined event, without interrupting the power supply to the low-voltage vehicle electrical system.

In other words, in the event of an accident, all high-voltage connections of the energy store can be switched off and currentless by the safety isolating elements, while the voltage supply to the low-voltage vehicle electrical system is maintained. This aspect enables the low-voltage vehicle electrical system to be supplied from the energy store, even if the high-voltage supply had to be switched off for safety reasons.

If the safety separators are irreversible separators such as Pyrofuses are, the safety isolating elements can optionally be additionally connected in series with a switchable isolating element or have this integrated. In this way, the high-voltage interfaces can be reversibly de-energized for maintenance or service.

The energy storage device preferably has switchable isolating elements which are set up to selectively isolate the high-voltage/low-voltage DC/DC converters from the storage strings.

In an advantageous embodiment, the energy store comprises switchable isolating elements which are set up to selectively switch off the low-voltage interfaces.

The above aspects allow for granular control of current paths. In this way, current flows can be diverted around defective components, short circuits can be electrically isolated and the energy supply of particularly relevant consumers can be prioritized.

An electrically drivable vehicle with an energy store according to the invention is also provided. In addition to the energy storage device, the vehicle can have a high-voltage vehicle electrical system and a low-voltage vehicle electrical system, with the high-voltage vehicle electrical system and the low-voltage vehicle electrical system each being fed by the energy storage device according to the invention.

• - 1 eine vereinfachte schematische Darstellung eines Energiespeichers mit zwei Hochvolt-Speichersträngen,
• - 2 eine vereinfachte schematische Darstellung eines Energiespeichers mit drei Hochvolt-Speichersträngen, und
• - 3 eine vereinfachte schematische Darstellung eines Energiespeichers mit vier Hochvolt-Speichersträngen.

Further advantages and features of the invention result from the following descriptions and from the accompanying drawings, to which reference is made. Show it:

• - 1 a simplified schematic representation of an energy storage device with two high-voltage storage strings,
• - 2 a simplified schematic representation of an energy store with three high-voltage storage strings, and
• - 3 a simplified schematic representation of an energy store with four high-voltage storage strings.

The individual components are usually designated according to their function and, if necessary, grouped together. Electrical couplings of the respective components in the electrical circuit are given via direct or indirect connections. Features and functions that have already been described in connection with a figure are only repeated in the context of the other figures if this appears necessary for better understanding.

In 1 a simplified schematic overview of an energy store 1 for an electrically driven vehicle is shown. The energy store 1 has two high-voltage storage strings 10, 20 connected in parallel. The high-voltage storage strings 10, 20 each include a first and a second series-connected sub-storage string 11, 12, 21, 22 with an intermediate center tap 13, 23. The first sub-storage strings 11, 21 each include one with the respective high-voltage DC voltage source of the sub-storage string 11, 21 switchable isolating element 14, 24 arranged in series connection. The isolating element 14, 24 is closed during normal operation. It is preferably designed as a make contact, i.e. open without current or with high resistance when not activated. Alternatively, it can be designed as an opener. Two of the high-voltage storage strands 10, 20 can be electrically coupled at the center taps 13, 23 via a switching element 51. The two center taps 13, 23 connecting switching element 51 is normally open, and can therefore preferably also be designed as a closer.

The energy store 1 includes a high-voltage interface 61 for supplying energy to a high-voltage vehicle electrical system and two low-voltage interfaces 62, 63 for supplying energy (each) to a low-voltage vehicle electrical system. Of course, in other design variants, more (or fewer) than two low-voltage interfaces can also be supplied. The high-voltage interface 61 is coupled to the high-voltage storage strands 10, 20.

The energy store 1 also has a high-voltage/low-voltage direct current converter 71 . The high-voltage/low-voltage DC converter 71 is fed from one of the first partial storage strings 11, 21. The low-voltage interface 62 is coupled to the high-voltage/low-voltage direct current converter 71 .

The second sub-storage strings 12, 22 each include a switchable isolating element 15, 25 connected in series with the high-voltage DC voltage source. The isolating element 15, 25 is a make contact which is normally open or has a high resistance in the case of a semiconductor switch without activation. Alternatively, the separating element can also be an opener. To reduce the electrical components, one of the separating elements 14, 15, 24, 25 either in the first partial storage line 11, 21 or in the second partial storage line 12, 22 can alternatively be omitted.

The separating elements 14, 24, 15, 25 in the first and second partial storage strings 11, 21, 12, 22 can preferably be arranged in such a way that a separating element 14, 24, 15, 25 is located on each side of the high-voltage voltage sources. In other words follows in the respective high-voltage storage strings 10, 20 in a series connection to a first separator element 14, 24, the high-voltage DC voltage source of the first partial storage string 11, 21. The first partial storage string 11, 21 follows, between the first partial storage string 11, 21 and the second Sub-storage string 12, 22 lying, the center tap 13, 23. Following the center tap 13, 23, connected in series, is the high-voltage DC voltage source of the second sub-storage string 12, 22. Finally, the isolating elements 15, 25 in the second sub-storage strings 12, 22 follow. The at least two high-voltage storage strings 10, 20 are connected in parallel, i.e. electrically coupled before the isolating elements 14, 24 of the first partial storage strings 11, 21 and after the isolating elements 15, 25 of the second partial storage strings 12, 22.

The switchable isolating elements 14, 24 in the first partial memory strings 11, 21 each comprise a semiconductor switch 141. The switchable isolating elements in the first partial memory strings 14, 24 have an electrically or electromagnetically actuatable switch 142 connected in series or in parallel with the semiconductor switch 141. This is shown as an example on the separating element 14 in the first partial storage branch 11 of the first high-voltage storage branch 10, but of course also applies to the other separating elements, also in the further partial storage branches and in the other embodiment variants.

In the embodiment shown, the energy store 1 has a second high-voltage/low-voltage direct-current converter 72 . The second high-voltage/low-voltage DC-DC converter 72 is fed from one of the first partial storage strings 11, 21, but can alternatively also be supplied with energy from one of the second partial storage strings 12, 22. The low-voltage interface 63 is coupled to the second high-voltage/low-voltage direct current converter 72 .

The high-voltage storage strings 10, 20 and the high-voltage/low-voltage direct-current converters 71, 72 are arranged in a common housing 85. The energy store 1 has activatable safety isolating elements P1, P2. The safety isolating elements P1, P2 are set up in order to separate the high-voltage interface 61 from the high-voltage storage strands 10, 20 in the event of a defined event (such as an accident, a short circuit or another error) without the energy supply to the low-voltage Interfaces 62, 63 to interrupt. If the safety isolating elements are irreversible isolating elements such as pyrofuses, the safety isolating elements can optionally also be connected in series with a switchable isolating element or have this integrated.

The energy store 1 includes switchable isolating elements 91, 92 which are set up to selectively disconnect or connect the high-voltage/low-voltage DC/DC converters 71, 72 from the storage strings 10, 20. In this way, for example, particularly efficient operation in the partial load range is made possible.

The energy store 1 has switchable isolating elements 91, 92 which are set up to selectively switch off the low-voltage interfaces 62, 63 and optionally to separate the still-voltage low-voltage DC-DC converter on the high-voltage side from the high-voltage storage strands in the event of a fault. The separating elements for separating the high-voltage/low-voltage DC-DC converters 71, 72 from the high-voltage storage strands 10, 20 can (depending on the circuit design) be the same as the separating elements 91, 92 in order to selectively switch the low-voltage interfaces currentless.

The high-voltage storage strings 10, 20 are arranged in a battery housing 81, 82, 83.

2 shows a simplified schematic representation of an embodiment variant of the energy store 1. The energy store 1 comprises three of the high-voltage storage strands 10, 20, 30.

The center taps 13, 23, 33 can be coupled in a ring shape via the switching elements 51, 52, 53. The ring-shaped coupling is also possible and advantageous in design variants with more than three high-voltage storage strings.

In the variant shown, the energy store 1 has only one high-voltage/low-voltage direct-current converter 71 on the first partial storage line 11 . However, in a modified variant, it can also have a second and/or a further high-voltage/low-voltage direct-current converter 71, 73.

The switching elements 51, 52, 53 each comprise a semiconductor switch 531. The switching elements 51, 52, 53 have an electrically or electromagnetically actuatable switch 532 connected in series with the semiconductor switch 531. This is shown as an example on the switching element 53 between the third and the first center tap 33, 31, but of course also applies to the other switching elements that connect the center taps in a couplable manner, also in the further embodiment variants.

By opening the isolating elements 14, 15 of the first and second partial storage strings 11, 12 (and with the switching elements 51, 53 open), the first high-voltage/low-voltage DC-DC converter 71 can be selectively separated from the storage strings 10, 20, 30. In this way, the Nieder volt interface 62 selectively de-energized. Alternatively, separate separating elements can be provided for this.

In each case one high-voltage storage string 10, 20, 30 is arranged in a battery housing 81, 82, 83.

3 shows a simplified schematic representation of a further embodiment of the energy store 1. The energy store 1 comprises four of the high-voltage storage strands 10, 20, 30, 40.

In the embodiment shown, the energy store 1 has a second high-voltage/low-voltage direct-current converter 72 . The second high-voltage/low-voltage DC-DC converter 72 is fed from one of the second partial storage strings 12, 22, 32, 42, but in an alternative variant it can also be supplied with energy from one of the first partial storage strings 11, 21, 31, 41. The low-voltage interface 63 is coupled to the second high-voltage/low-voltage direct current converter 72 .

The energy store 1 has a further high-voltage/low-voltage direct current converter 73 . The other high-voltage/low-voltage DC converter 73 is fed from one or more of the high-voltage storage strings 10, 20, 30, 40, depending on the switching position of the isolating elements 14, 24, 15, 25.

The switchable isolating elements 15, 25, 35, 45 in the second partial storage strings 12, 22, 32, 42 each include a semiconductor switch 151.

The switchable isolating elements in the second partial storage strings 15, 25, 35, 45 have an electrically or electromagnetically actuatable switch 152 connected in parallel with the semiconductor switch 151. This is shown as an example on the separating element 15 in the second partial storage branch 12 of the first high-voltage storage branch 10, but of course also applies to the other separating elements, also in the further partial storage branches and the other design variants. In this way, losses are reduced. In a further embodiment variant, the semiconductor switches and the electrically or electromagnetically actuable switches are connected in series. The switchable isolating elements can be designed as normally open contacts (normally open or, in the case of semiconductor switches, high-impedance without activation). Each of the separating elements can be a safety separating element. The aspects mentioned promote a safe interruption of the current flow.

By opening the isolating elements 14, 15, 44, 45 of the first and second partial storage string 11, 12, 41, 42 (and with open switching elements 51, 53) of the first and fourth high-voltage storage string 10, 40, the first and second high-voltage low-voltage - DC-DC converters 71, 72 are selectively separated from the storage strands 10, 20, 30, 40. In this way, the low-voltage interface 62, 63 can be selectively switched off. Alternatively, separate separating elements can be provided for this.

The energy store 1 can optionally have switchable isolating elements (not shown here), which are set up to selectively isolate the high-voltage/low-voltage DC/DC converters 73 from the storage strings 10, 20.

The energy store 1 also has switchable isolating elements 93 which are set up to selectively switch the low-voltage interfaces 64 currentless.

Two high-voltage storage strings 10, 20 or 30, 40 are arranged in a battery housing 81, 82 in each case.

Claims (13)

Energy store (1) for an electrically drivable vehicle, with at least two parallel-connected storage strands (10, 20, 30, 40), wherein the energy store has a first interface (61) and a second interface (62), the first interface (61 ) is coupled to the storage strings (10, 20, 30, 40), the energy storage device (1) comprising a DC-DC converter (71), the second interface (62-64) being coupled to the DC-DC converter (71), the storage strings (10, 20, 30, 40) and the DC-DC converter (71) are arranged in a common housing (85), the energy store (1) having activatable safety isolating elements (P1, P2) and the activatable safety isolating elements (P1, P2) being set up To separate the first interface (61) from the storage strands (10, 20, 30, 40) at a defined event without interrupting the power supply at the second interface (62-64), thereby marked This means that the storage strings (10, 20, 30, 40) are high-voltage storage strings and each have at least a first and a second series-connected sub-storage string (11, 12; 21, 22; 31, 32; 41, 42) with an intermediate center tap (13, 23, 33, 43), each partial storage string containing at least one high-voltage DC voltage source and the high-voltage direct voltage source having a potential difference of at least 60 volts, the first partial storage strings (11, 21, 31, 41) each having a switchable isolating element (14, 24, 34, 44) arranged in series sen, and two of the high-voltage storage strings (10, 20, 30, 40) can be electrically coupled at the center taps (13, 23, 33, 43) via a switching element (51, 52, 53), the first interface (61 ) is a high-voltage interface for supplying energy to a high-voltage vehicle electrical system, the second interface (62-64) being a low-voltage interface for supplying energy to a low-voltage vehicle electrical system, the DC/DC converter (71) being a high-voltage/low-voltage DC/DC converter and consisting of one of the first partial storage strings (11, 21, 31, 41) is fed. Energy storage (1) after claim 1 , wherein the second partial storage strings (12, 22, 32, 42) each comprise a switchable isolating element (15, 25, 35, 45) connected in series. Energy store (1) according to one of the preceding claims, wherein the switchable isolating elements (14, 15; 24, 25; 34, 35; 44, 45) each comprise a semiconductor switch (141). Energy storage (1) after claim 3 , wherein the switchable isolating elements (14, 15; 24, 25; 34, 35; 44, 45) have an electrically or electromagnetically operable switch (142) connected in parallel or in series with the semiconductor switch (141). Energy store (1) according to one of the preceding claims, wherein the energy store (1) has a second high-voltage/low-voltage direct current converter (72), the second high-voltage/low-voltage direct current converter (72) consisting of one of the first or second partial storage strings (11, 12 ; 21, 22; 31, 32; 41, 42) and wherein the low-voltage interface (63) is coupled to the second high-voltage/low-voltage direct current converter (72). Energy store (1) according to one of the preceding claims, wherein the energy store (1) has a further high-voltage/low-voltage direct current converter (73), the further high-voltage/low-voltage direct current converter (73) consisting of one or more of the high-voltage storage strands (10, 20, 30, 40). Energy store (1) according to one of the preceding claims, wherein the energy store (1) comprises at least three of the high-voltage storage strands (10, 20, 30, 40). Energy storage (1) after claim 7 , wherein the center taps (13, 23, 33, 43) can be coupled in a ring shape via the switching elements (51, 52, 53). Energy store (1) according to one of the preceding claims, wherein the energy store (1) comprises at least four of the high-voltage storage strands (10, 20, 30, 40). Energy store (1) according to one of the preceding claims, wherein in each case one high-voltage storage string (10, 20, 30, 40) or two high-voltage storage strings (10, 20, 30, 40) are arranged in a battery housing (81, 82, 83). are. Energy store (1) according to one of Claims 1 until 10 , wherein the energy store (1) comprises switchable isolating elements (91, 92) which are set up to selectively separate the high-voltage/low-voltage DC-DC converter (71, 72, 73) from the storage strings (10, 20, 30, 40). Energy store (1) according to one of Claims 1 until 11 , wherein the energy store (1) comprises switchable isolating elements which are set up to selectively switch off the low-voltage interfaces (62, 63, 64). Electrically drivable vehicle with an energy store (1) according to one of the preceding claims.

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