DE102019102030A1 - Stationary charging device with integrated battery storage for providing electrical energy either from a power supply system or from the battery storage at a charging connection for an electrically drivable motor vehicle and corresponding operating method for the charging device - Google Patents

Abstract

The invention relates to a stationary charging device (10) for providing electrical energy from a power network (11) at a charging connection (14) for an electrically drivable motor vehicle (12), a stationary electrical energy store (17) for temporarily storing at least a portion of the Energy is provided and an AC-DC converter (19) for transferring the energy from the power grid (11) into a DC intermediate circuit (20) and a DC-DC converter (21) for the controlled transfer of the part of the energy from the DC intermediate circuit (20) is provided in a memory intermediate circuit (22) of the energy store (17) and the charging connection (14) has its own DC charging converter (23) for controlled energy delivery to the motor vehicle (12). The invention provides that a switch arrangement (28) is provided, by means of which the DC charging converter (23) of the charging connection (14) is connected to the DC intermediate circuit (20) via a first switch unit (S1) and via a second switch unit (S2 ) is connected to the memory intermediate circuit (22).

Description

The invention relates to a stationary charging device with integrated battery storage, by means of which electrical energy can be provided either directly from a power supply and / or from at least one battery in the battery storage for an electrically drivable motor vehicle (e.g. electric vehicle or hybrid vehicle). The charging device has a charging connection which can be connected to the motor vehicle in order to transmit the electrical energy into the motor vehicle. The energy is transmitted by means of DC voltage. The charging device also has an electrical energy store for temporarily storing energy, so that the entire energy does not have to be drawn directly from the power supply during a charging process or, depending on the further application situation (legal regulations), electricity can only be drawn from the power supply or only from the battery . The former application situation can e.g. be provided for a so-called boost charging if the power supply connection is made smaller or less powerful than the charging connection on the power and current side. The invention also includes a method for operating the loading device.

A charging device of the type mentioned with its own electrical energy store for temporarily storing electrical energy can have a construction as will be described below with reference to 1 is described. A charging device is shown therein 10 ' connected to an electrical grid 11 can be connected, that is, to a public energy supply network or to a local energy supply network. Through the power grid 11 an alternating current can be provided. The charger 10 ' can be provided for this purpose, electrical energy for charging a traction battery of an electrically drivable motor vehicle 12th To provide, for example, an electric vehicle or a hybrid vehicle. The car 12th can be a charging socket 13 to which a charging port 14 ' , for example a charging plug, can be connected. The charger 10 ' can be designed in two parts, but this is optional. This two-part design can be an electrical stationary storage 15 ' and a charging station 16 ' to provide a DC voltage at the charging connection 14 ' provide.

To electrical energy from the power grid 11 to receive and at the charging port 14 ' provide and electrical energy in an electrical energy storage 17 ' to store between, a charging system can be provided, which is an optional transformer 18 ' , an AC-DC converter 19 ' (AC - AC, DC - DC), a DC link 20 ' , a DC-DC converter 21 ‚And a memory intermediate circuit 22 ' can have, with the memory intermediate circuit 22 ' another DC-DC converter for the charging connection 14 ' can be connected. For the sake of better distinction, this further DC-DC converter is better than a DC charge converter 23 ' designated. The charger 10 ' can over the transformer 18 ' with the power grid 11 be connected. From the transformer 18 ' can the AC-DC converter 19 ' electrical energy in the DC link 20 ' transfer. From there, the DC-DC converter can be used 21 ' electrical energy in the intermediate storage circuit 22 ' transferred to the energy storage 17 ' charge. From the intermediate storage circuit 22 ' can by means of the DC charging converter 23 ' Energy from the power grid 11 (using the DC-DC converter 21 ' ) and / or the energy storage 17 ' received and to the charging port 14 ' be transmitted. Charging power can be achieved using the DC charging converter 23 ' can be controlled or adjusted in a known manner. The other way around, electrical energy from the motor vehicle 12th in the case of feedback in the opposite direction, either into the energy store 17 ' and / or the power grid 11 (using the DC-DC converter 21 ' ) be transmitted. 1 illustrates an electrical charging current path 24th the energy from the power grid 11 towards the motor vehicle 12th as it results from a charging process and a regenerative current path 25th of energy from the motor vehicle 12th into the power grid 11 as it results from a regeneration.

The energy must be exchanged with the power grid every time 11 (Charging and regeneration) both by the DC-DC converter 21 ' as well as the DC charging converter 23 ' be performed. As with every conversion stage, i.e. the conversion stage in the DC-DC converter 21 ' and the conversion stage in the DC charging converter 23 ' , there is also a power loss in each case, power loss is generated in two conversion stages, although only one conversion stage would be technically necessary. Would you like the DC charge converter 23` to the DC link 20 ' connect, these unnecessary losses would always arise if there is an energy exchange (charging and recovery) between the energy storage 17 ' and the motor vehicle 12th would be carried out. So there would be no efficiency gain.

From the WO 2018/153459 A1 a stationary battery storage device is known which can be connected to a power grid via a transformer, an AC-DC converter and a DC-DC converter. Switch units can be used to switch between different batteries in the battery storage.

From the DE 10 2017 116 070 A1 is a system for an electric quick charge Electric vehicle is known which, in addition to a connection to an electrical power network, also has a stationary battery, by means of which additional electrical charging power can be provided.

From the DE 10 2017 207 102 A1 is known in a charging device to connect a charging port for connecting an electric vehicle via a DC charging converter to a DC intermediate circuit, to which both a power supply system are connected via an AC-DC converter and a battery storage device via a DC-DC converter .

The invention has for its object to be able to operate a charging device with electrical energy storage for the temporary storage of energy efficiently.

The object is solved by the subject matter of the independent claims. Advantageous embodiments are described by the dependent claims, the following description and the figures.

The invention provides a stationary charging device, by means of which electrical energy can be provided from a power network at a charging connection for an electrically drivable motor vehicle. At the charging connection, the electrical energy is made available by means of DC voltage. In contrast, an AC voltage is drawn or received from the power grid. In the manner described, the charging device has a stationary energy store for temporarily storing at least part of the energy. The charging device has a charging system that is configured in the following manner. An AC-DC converter is provided to transfer energy from the power grid to a DC link. A DC-DC converter is provided for transferring at least part of the energy from the DC intermediate circuit into a memory intermediate circuit of the energy store. The respective intermediate circuit (that is, DC intermediate circuit and memory intermediate circuit) can each be implemented, for example, on the basis of cables and / or busbars. Each is an electrical connection between the components that the respective intermediate circuit connects. Said charging connection for connection to the motor vehicle has its own DC charging converter for controlled energy delivery to the motor vehicle. The DC charging converter is a DC-DC converter in the manner described.

The charging system described thus corresponds to the charging system of the charging device described at the outset, with the exception of the connection of the DC charging converter to the intermediate storage circuit.

In order to enable efficient operation, a switch arrangement is provided according to the invention, by means of which the DC charging converter of the charging connection is connected to the DC link via a first switch unit and to the storage link via a second switch unit. In other words, the DC charge converter can alternately be electrically connected to either the DC link and the memory link by closing the respective switch unit, i.e. is switched electrically conductive. A switch unit can be implemented, for example, on the basis of at least one contactor and / or on the basis of at least one semiconductor circuit breaker.

The advantage of the invention is that electrical energy can be transferred from the power grid to the DC charging converter of the charging connection, bypassing the DC-DC converter, which from the point of view of the AC-DC converter leads to the energy store. In the same way, electrical energy can be transferred from the energy store to the DC charging converter of the charging connection, bypassing the DC-DC converter, which leads to the AC-DC converter from the point of view of the energy store. Thus, there is only one conversion stage by a DC-DC converter for the transmission of energy both from the power supply network to the charging connection and from the energy storage device to the charging connection, namely the DC charging converter. This advantageously eliminates a power loss that would arise in a second conversion stage.

In order to provide the charging device described, it can be provided that a charging station with integrated battery storage (stationary storage) or alternatively a battery storage (stationary storage) with integrated charging station is used as a basis.

The invention also includes embodiments which result in additional advantages.

In one embodiment, a control device of the switch arrangement is set up to keep the first switch unit closed and the second switch unit open for a first charging operation, in which a transfer of the energy from the mains supply to the charging connection is bypassed, bypassing the energy store. Thus, the DC-DC converter is bypassed when the energy is transmitted. The energy can be transferred directly from the AC-DC converter to the DC charging converter via the first switch unit. The opened second switch unit decouples the energy storage device from the DC charging converter. With a “closed” switch unit, one is electrical in the manner mentioned Conductively switched switch unit and an “open” switch unit generally means an electrically blocked switch unit. The DC-DC converter is of course deactivated or switched in each case.

In one embodiment, said control device is set up to keep the first switch unit open and the second switch unit closed for a second charging operation in which a transfer of energy from the energy store to the charging connection is provided. As a result, the energy can be transmitted directly from the intermediate storage circuit via the second switch unit to the DC charging converter, without the energy having to be transmitted to the intermediate DC circuit by the DC-DC converter. Thus, in the second charging mode as well as in the first charging mode, the DC-DC converter is bypassed during the transmission of the energy, that is to say its conversion stage is avoided. The DC-DC converter is of course deactivated or switched in each case.

So far, only the charging operation, that is to say a transfer of energy into the motor vehicle, has been described. In one embodiment, said control device for the switch arrangement is set up to keep the first switch unit closed and the second switch unit open when energy is fed back from the motor vehicle into the charging device for a first regenerative operation, in which the energy is fed back into the power grid. This means that the regenerated energy can also be conducted past the DC-DC converter. For a second regenerative operation, in which the energy is fed back into the energy store, it is provided that the control device keeps the first switch unit open and the second switch unit closed. As a result, the regenerated energy is transferred directly from the DC charging converter via the second switch unit to the intermediate storage circuit and from there to the energy store. Thus the DC-DC converter is bypassed or bypassed here too. The DC-DC converter is of course deactivated or switched in each case.

The charging device can also be of modular design in order to be able to supply several motor vehicles. In one embodiment, in addition to the described charging system, the AC-DC converter, the DC intermediate circuit, the DC-DC converter, the memory intermediate circuit, the energy store, the switch arrangement and the charging connection with DC charging converter are at least one more provided such charging system. However, these two or more than two charging systems are then not provided independently of one another, but the charging systems are connected to one another in pairs by a connection switch arrangement. This has the advantage that components or parts of one of the charging systems can also be used by another of the charging systems by switching an appropriate electrical connection in the connection switch arrangement.

Thus, in one embodiment, a switch control of the respective connection switch arrangement (by means of which two of the charging systems are connected to one another) is set up to provide additional energy for the rapid charging operation (boost charging) of a motor vehicle at the charging connection of one of the charging systems by closing a connection switch unit of the connection switch arrangement from another the charging systems. In other words, energy can be provided at a charging connection, which is not only drawn exclusively from the own charging system, i.e. via its AC-DC converter or from its energy store, but an additional portion of energy can be obtained from another charging system, i.e. can be obtained from its AC-DC converter or from its energy storage.

In one embodiment, the respective connection switch arrangement between two charging systems provides for the DC intermediate circuits of the two charging systems to be connected to one another via a respective connection switch unit and for the switch control of this connection switch arrangement to be set up for charging operation from the power supply system by means of the Connection switch unit, which connects the two DC intermediate circuits, to connect electrically. For this purpose, the connection switch unit is closed or switched to be electrically conductive. This connection means that the DC-DC converters of both charging systems are no longer involved in the charging process, i.e. they are bridged. A connection switch unit can be formed on the basis of at least one contactor and / or at least one power semiconductor.

In one embodiment, the respective connection switch arrangement of two charging systems connects the vehicle-side outputs of the DC charging converters to one another via a respective connection switch unit. In other words, a direct electrical connection between the two charging connections can be provided by closing this connection switch unit. The switch control of the connection switch arrangement is set up for charging operations from the energy stores of the two charging systems to the vehicle-side outputs by means of the connection switch unit thereof To connect outputs electrically. In other words, electrical energy can be provided from the energy store of each of the two charging systems via its own DC charging converter at the charging port of one of the charging systems, in that part of the energy is conducted via the closed connection switch unit of the charging ports. Thus, energy can also be drawn from the energy stores of the charging systems and the DC-DC converters of the two connected charging systems can be bypassed or bypassed.

The control device described for the switch arrangement of each charging system and the switch control described for the connection switch arrangement between two charging systems can each be implemented on the basis of a microcontroller and / or a microprocessor and / or a logic circuit. The switching operations can be implemented on the basis of a program module or software, the program instructions of which can be stored in a data memory of the control device or the switch control. The following instructions, which also belong to the invention, can be implemented in particular by the program instructions.

The method according to the invention provides for operating a charging device with the components described. In this case, the control device of the switch arrangement electrically bridges or bypasses the DC-DC converter by means of the switch arrangement during charging operation of a motor vehicle at the charging connection. This avoids the conversion stage of the DC-DC converter during charging. In the same way, the conversion stage can also be avoided in the manner described in the case of energy recovery. The DC-DC converter is only necessary or provided to supply or charge the energy store with energy from the power grid and / or to feed energy from the energy store back into the power grid.

The invention also includes developments of the method according to the invention with features that have already been described in connection with the developments of the charging device according to the invention. For this reason, the corresponding developments of the method according to the invention are not described again here.

A recharging process and / or an electrical feedback for an electrically drivable motor vehicle can be implemented in the manner described by means of the charging device. Within the scope of the invention, a motor vehicle in particular includes a motor vehicle (for example a passenger car and / or truck) and / or a passenger bus and / or an industrial truck and / or an aircraft and / or a helicopter and / or a drone and / or a ship to understand.

The invention also includes combinations of the features of the described embodiments.

Further features of the invention result from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the combination indicated in each case, but also in other combinations or on their own.

• 1 eine schematische Darstellung einer Ausführungsform einer Ladevorrichtung gemäß dem Stand der Technik; und
• 2 eine schematische Darstellung einer Ausführungsform der erfindungsgemäßen Ladevorrichtung.

An exemplary embodiment of the invention is described below. This shows:

• 1 a schematic representation of an embodiment of a loading device according to the prior art; and
• 2nd is a schematic representation of an embodiment of the loading device according to the invention.

In the figures, the same reference numerals designate elements that have the same function.

2nd shows a loading device 10th , by means of which electrical energy from a power grid 11 in a motor vehicle 12th can be transferred to in the motor vehicle 12th to charge an energy store, for example a traction battery. In the manner described, the motor vehicle 12th a charging socket for this 13 exhibit. The car 12th can via its charging socket 13 with a charging port 14 the charger are electrically connected. To the electrical energy from the power grid 11 towards the charging port 14 to transfer, the loading device 10th via a transformer 18th to the power grid 11 be connected. About the transformer 18th an alternating voltage, for example multi-phase than three times 400 volts AC, can be received. Energy from the power grid 11 can then by means of an arrangement, here as a charging system 26 is referred to, on the one hand, in an energy store 17th cached and secondly at the charging port 14 to be provided. The energy storage 17th can be an electrochemical accumulator, for example based on lithium, lead, redox flow, hydrogen, to name just a few. The energy store can also provide storage, for example, as a pumped storage power plant and / or as a rotary store. It can described structural separation in stationary storage 15 and charging station 16 be provided.

The charging system 26 can provide energy from the grid 11 using an AC-DC converter 19th into a DC link or DC link 20 transferred to. From the DC link 20 can the energy or part of the energy by means of a DC-DC converter 21 into a storage intermediate circuit of the energy store 17th are transmitted, that is, to connections of the energy store 17th . Thus, by means of the DC-DC converter 21 the energy store with energy from the power grid 11 to be charged.

For setting or controlling an energy output of the charging connection 14 to the motor vehicle 12th can for the charging port 14 a separate DC-DC converter can be provided, which acts as a DC charging converter in the manner mentioned 23 is designated. The charging port 14 can be at a vehicle-side output 27 of the DC charging converter 23 be connected. The DC charging converter 23 can by means of a switch arrangement 28 both with the DC link 20 as well as the intermediate storage circuit 22 via a respective switch unit S1 , S2 be connected. In other words, by the switch arrangement 28 a first switch unit S1 be provided, through which the DC charging converter 23 directly with the DC link 20 is connected or connected. Furthermore, by the switch arrangement 28 a second switch unit S2 be provided, through which the DC charging converter 23 directly with the intermediate storage circuit 22 is electrically connected or connected. For switching or controlling the switch units S1 , S2 can be a control device 29 the switch arrangement 28 be provided. The control device 29 can be configured in the manner described, for example on the basis of a microcontroller and / or a microprocessor and / or a logic circuit.

For energy transfer between the power grid 11 and the charging port 14 (both directions of transmission, i.e. charging and regeneration) can be done by the control device 29 the switch unit S1 closed and the switch unit S2 be kept open. Thus the DC-DC converter 21 bypassed or omitted in this energy transfer. For an energy transfer between the energy storage 17th and the charging port 14 (both directions of transmission) can by the control device 29 the switch unit S1 opened and the switch unit S2 be kept closed. This also makes the DC-DC converter for this energy transfer 21 bypassed or omitted. By the control device 29 can therefore always only one of the switch unit during a charging process and during regeneration S1 , S2 closed while the other is kept open. For an energy exchange between the AC-DC converter 19th and the energy storage 17th can be provided by the control device 29 both switch units S1 , S2 be kept open. So the charging port 14 from the DC intermediate circuits 20 , 22 decoupled.

The transformer described 18th can optionally be provided. When electrical isolation from the power supply is required 11 This can be done, for example, even without a transformer by means of electrical isolation in the DC-DC converter 21 and / or in the DC charging converter 23 be provided.

2nd illustrates regardless of how the loader 10th can be modular, in addition to the charging system 26 another charging system 26 ' can be provided, which can be configured in the same manner as the charging system 26 . The charging system 26 ' can have another transformer 30th with the power grid 11 or another power grid. From the charging system 26 ' For the sake of brevity, only the components relevant for further explanation are described below. By means of the charging system 26 ' can be another motor vehicle 31 can be charged with electrical energy or there can be feedback from the motor vehicle 31 respectively. The charging systems 26 , 26 ' can via a connection switch arrangement 32 be interconnected, here the DC link 20 of the charging system 26 with a corresponding DC link 33 of the charging system 26 ' via a first connection switch unit S3 can be connected or connected. The motor vehicle exit 27 of the DC charging converter 23 can with a corresponding motor vehicle-side output 34 of a DC charging converter 35 of the charging system 26 ' via a connection switch unit S4 connected or coupled. 2nd illustrated by ellipsis 36 that one more charging system or more charging systems in the same way with one of the charging systems 26 , 26 ' can be connected.

For switching the connection switch units S3 , S4 can for the connection switch assembly 32 a switch control 37 be provided. The switch control 37 can be configured in the manner described, for example on the basis of a microcontroller and / or a microprocessor and / or a logic circuit. To the motor vehicle 12th via the charging port 14 to provide with a charging power that can be greater than a transmission power by the charging system 26 itself can be provided by means of the connection switch arrangement 32 additional energy for this Charging process from the charging system 26 ' received or branched off. Should the energy from the power grid 11 can be removed by the switch control 37 the connection switch unit S3 closed and the connection switch unit S4 be kept open. Should the energy for the charging process from the energy storage 17th and an energy storage 38 of the charging system 26 ' can be removed by the switch control 37 the connection switch unit S3 opened and the connection switch unit S4 be kept closed.

This means that two charging systems can also be operated together 26 , 26 ' for charging a motor vehicle 12th each the DC-DC converter 21 of the charging system 26 and a DC-DC converter 39 of the charging system 26 ' bridged or bypassed.

Even with the stationary charging device 10th according to 2nd can therefore an electrochemical stationary storage with the energy storage (lithium, lead, redox flow, hydrogen, etc.) is constructed with the following high-voltage architecture: galvanically isolating transformer, AC-DC inverter, DC-DC actuator, energy storage. According to 1 According to the prior art, only one DC-coupled charging station can be connected to the high-voltage architecture of the charging system via the battery DC link. Alternatively, this connection could also be made via the DC link (not shown).

Disadvantages in the construction according to 1 : If an electric car were charged directly from the power grid (without going through the battery), two DC / DC conversion stages would be used, which would unnecessarily reduce the efficiency of charging by 1 to 5 percentage points. The same disadvantage exists if the electric car were fed back into the power grid (discharged). Disadvantages of the alternative structure: If an electric car were charged from the energy storage, two DC / DC conversion stages would also be used, which would unnecessarily worsen the degree of charging efficiency by 1 to 5 percentage points. The same disadvantage exists if the electric car feeds back (discharges) into the energy store.

In 2nd the solution to the problem is outlined. A bypass circuit in the form of the switch arrangement 28 is able to switch back and forth flexibly. Thus, when charging the electric car from the power grid, the lower conversion steps can be carried out by closing the switch unit S1 use. However, if an electric car is to be charged from the energy store, then a switch unit is sufficient S1 to open and switch unit S2 close. The same procedure applies if the electric car is to feed (discharge) back into the power grid or energy store.

The charger 10th improves the overall efficiency by at least 1 to 5 percentage points. Depending on the application, it may happen that an electric car has to be charged either from the power grid or from the stationary energy storage device within a few minutes (so that it has to be switched over). The charger 10th presents a solution for flexible optimization of the system efficiency, thereby reducing the current electricity costs for the operator of the system and thus the price per kWh charged for the end customer (driver of the electric car).

Overall, the examples show how the invention can be used to implement an HV bypass circuit in an electrical stationary memory in order to optimize the efficiency of a DC-coupled charging operation.

Reference list

10, 10 '

Loading device

11

power grid

12th

Motor vehicle

13

Charging socket

14

Charging port

15, 15 '

Stationary storage

16, 16 '

Charging station

17, 17`

Energy storage

18, 18 '

transformer

19, 19 '

AC-DC converter

20, 20 '

DC link

21, 21 '

DC-DC converter

22, 22`

DC link memory

23, 23 '

DC charging converter

24th

Charging current path

25th

Regenerative current path

26, 26 '

Charging system

27

output

28

Switch arrangement

29

Control device

30th

transformer

31

Motor vehicle

32

Connection switch arrangement

33

DC link

34

output

35

DC charging converter

36

Ellipsis

37

Switch control

38

Energy storage

39

DC-DC converter

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• WO 2018/153459 A1 [0005]
• DE 102017116070 A1 [0006]
• DE 102017207102 A1 [0007]

Claims (9)

Stationary charging device (10) for providing electrical energy from a power network (11) at a charging connection (14) for an electrically drivable motor vehicle (12), a stationary energy store (17) being provided for temporarily storing at least part of the energy and one AC-DC converter (19) for transferring the energy from the power grid (11) to a DC link (20) and a DC-DC converter (21) for transferring the part of the energy from the DC link (20) is provided in a storage intermediate circuit (22) of the energy store (17) and the charging connection (14) has its own DC charging converter (23) for controlled energy delivery to the motor vehicle (12), characterized in that a switch arrangement (28) The DC charging converter (23) of the charging connection (14) is provided via a first switch unit (S1) with the DC intermediate circuit (20) and via a second switch unit (S2) with the storage intermediate circuit (22) is connected. Loading device (10) after Claim 1 A control device (29) of the switch arrangement (28) is set up for a first charging operation in which a transfer of the energy from the power network (11) bypassing the energy store (17) to the charging connection (14) is provided, to keep the first switch unit (S1) closed and to keep the second switch unit (S2) open. Loading device (10) after Claim 2 The control device (29) is set up to open the first switch unit (S1) and the second switch unit (S2.) for a second charging operation, in which a transfer of the energy from the energy store (17) to the charging connection (14) is provided ) to keep closed. Loading device (10) according to one of the Claims 2 or 3rd The control device (29) is set up to, when energy from the motor vehicle (12) is fed back into the charging device (10) for a first regenerative operation, in which the energy is fed back into the power network (11), the first switch unit ( S1) closed and keep the second switch unit (S2) open, and for a second regenerative operation, in which the energy is fed back into the energy store (17), the first switch unit (S1) opened and the second switch unit (S2) kept closed. Charging device (10) according to one of the preceding claims, wherein, in addition to the charging system (26), AC-DC converter (19), DC intermediate circuit (20), DC-DC converter (21), memory intermediate circuit (22) , Energy storage device (17), switch arrangement (28) and charging connection (14) with DC charging converter (23) at least one further charging system (26 ') of the same type is provided and the charging systems (26, 26') in pairs with each other via a respective connection switch arrangement (32) are connected. Loading device (10) after Claim 5 A switch control (37) of the respective connection switch arrangement (32) of two of the charging systems (26, 26 ') is set up to provide additional energy by closing the charging connection (14) of one of the charging systems (26) for fast charging operation of a motor vehicle (12) a connection switch unit (S3, S4) of the connection switch arrangement (32) from the other of the charging systems (26 '). Loading device (10) according to one of the Claims 5 or 6 The DC link circuits (20, 33) of two charging systems (26, 26 ') are connected to one another via a respective connection switch unit (S3) and the switch control (37) is set up for charging operation by the respective connection switch arrangement (32) to electrically connect the DC intermediate circuits (20, 33) to the power network (11) by means of the connection switch unit (S3) connecting the DC intermediate circuits (20, 33). Loading device (10) according to one of the Claims 5 to 7 , With the respective connection switch arrangement (32), the vehicle-side outputs (27, 34) of the DC charging converters (23, 35) of two charging systems (26, 26 ') are interconnected via a respective connection switch unit (S4) and the switch controller (37 ) is set up to electrically connect the vehicle-side outputs (27, 34) for charging operation from the energy stores (17, 38) of the charging systems (26, 26 ') by means of the connection switch unit (S4) connecting the outputs (27, 34). Method for operating a charging device (10) according to one of the preceding claims, wherein a control device (29) of a switch arrangement (28) of the charging device (10) during a charging operation of a motor vehicle (12) at a charging connection (14) of the charging device (10) a DC-DC converter (21) of the charging device (10) is bridged electrically by means of the switch arrangement (28).

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