Charging device for charging an electrical energy storage device that can be connected to the charging device

Abstract

Charging device (30) for charging an electrical energy storage device (14) of an electrically powered motor vehicle that can be connected to the charging device (30), comprising: - a first connection unit (16) for connecting to the electrical energy storage device (14), - a second connection unit (18) for connection to a multi-phase AC electrical network (12), with one connection element for each phase of the multi-phase AC electrical network (12), - exactly one charging module (32, 34, 36) per phase of the multi-phase AC electrical network (12), wherein each of the charging modules (32, 34, 36) has a respective AC voltage connection (56, 58, 60) for supplying a single-phase AC electrical voltage and a respective DC voltage connection (62, 64, 66) for providing a DC electrical voltage, wherein the AC voltage connection (56, 58, 60) is connected to the connection element of the phase (P1, P2, P3) of the multi-phase AC electrical network (12) assigned to the charging module (32, 34, 36), wherein the DC voltage connections (62, 64, 66) of the charging modules (32, 34, 36) are connected in series to the first connection unit (16), wherein each of the charging modules (32, 34, 36) is connected at its The DC voltage connection (62, 64, 66) has a bypass diode (50, 52, 54).

Description

[0001] The present invention relates to a charging device for charging an electrical energy storage device of an electrically powered motor vehicle that can be connected to the charging device, comprising a first connection unit for connecting to the electrical energy storage device, a second connection unit for connecting to a multi-phase AC electrical network, with one connection element for each phase of the multi-phase AC electrical network, and at least one charging module per phase of the multi-phase AC electrical network, wherein each of the charging modules has a respective AC voltage connection for supplying a single-phase AC electrical voltage and a respective DC voltage connection for providing a DC electrical voltage.wherein the AC voltage connection is connected to the connection element of the phase of the multi-phase AC electrical network assigned to the charging module. Furthermore, the invention relates to an electrically powered motor vehicle with an electrical system comprising an electrical energy storage device and a drive unit connected to the electrical system, wherein the electrical system comprises a charging device connected to the electrical energy storage device for charging the electrical energy storage device, a connection unit for connecting to a multi-phase AC electrical network, which has one connection element for each phase of the multi-phase AC electrical network, and at least one charging module per phase of the multi-phase AC electrical network.wherein each of the charging modules has a respective AC voltage connection for supplying a single-phase alternating current and a respective DC voltage connection for providing a direct current, the AC voltage connection being connected to the connection element of the phase of the multi-phase alternating current network assigned to the charging module. Finally, the invention also relates to a method for charging an electrical energy storage device of an electrically powered motor vehicle connected to a charging device, wherein the charging device is supplied with electrical energy from a multi-phase alternating current network by connecting at least one charging module with a respective AC voltage connection to each phase of the multi-phase alternating current network.wherein a single-phase alternating current is supplied to the charging module via its respective AC voltage connection, wherein each charging module provides a direct current voltage at a respective DC voltage connection by converting the electrical energy supplied on the AC side.

[0002] A charging device of this type, as well as a method of charging an electrical energy storage device of an electrically powered motor vehicle connected to the charging device, is known, for example, from US 2015 / 0180252 A1. A three-phase AC power grid, formed here by a public power supply network, is connected to a primary side of a three-phase AC transformer. On the secondary side, the three-phase AC transformer is connected with each phase to a center terminal of a half-bridge module comprising two series-connected semiconductor switches. The half-bridge modules are connected in parallel with respect to their series connection and thus form a common DC link.Two further half-bridge modules are connected to the DC link, their center terminals each leading to a low-pass filter, which provides a DC voltage. These two half-bridge modules operate as DC / DC converters to generate other DC voltages from the DC link in a predefined manner. These can be used to charge the batteries of electric vehicles.

[0003] An electrically powered motor vehicle is a vehicle equipped with an electric drive unit that, during normal operation, provides at least a portion of the necessary mechanical power for propulsion. If the vehicle has only an electric drive unit, it is an electric vehicle. However, if the vehicle is also equipped with an internal combustion engine to enable normal operation, it is a hybrid vehicle. In a hybrid vehicle, the electric drive unit and the internal combustion engine can operate simultaneously during normal operation.

[0004] Modern electric vehicles of the aforementioned type require high-performance onboard charging systems for the rapid charging of the vehicle's energy storage system. This energy storage system is typically a high-voltage battery or accumulator designed for a direct current voltage in the range of several hundred volts. To implement a high-performance charging system, it is often designed for connection to a three-phase alternating current network, namely the public power grid. The alternating current of the public power grid, which is commonly used in this context, is approximately 400 V at 50 Hz. Standardized connectors, capable of carrying 16 or 32 amps per phase, can supply the charging system with an electrical power output of 11 kW or 22 kW.The three-phase alternating voltage can be provided, for example, via power connections at charging stations, as defined by the IEC 62196 standard, type 2, or directly via a CEE three-phase connector, as defined, for example, in the IEC 60309 standard.

[0005] Current state-of-the-art charging devices of this type typically have power outputs of 3.6 kW or 7.2 kW. If the power output is 7.2 kW, active phase switching is often incorporated to reduce phase imbalance in the three-phase AC network. This is also regulated by standards, such as the Low Voltage Directive VDE-AR-N 4105 for apparent power outputs greater than 3.69 kVA. These charging devices form a self-contained unit with a homogeneous design.

[0006] Although the aforementioned state of the art has proven effective, the requirement for a complex power module within the charging device for phase switching proves to be a disadvantage. This also hinders a structured design that could offer manufacturing advantages. Furthermore, the power provided by the aforementioned three-phase AC grid is not fully utilized. This results in comparatively long charging times for the high-voltage battery. Additionally, it is disadvantageous that phase connections with corresponding line protection devices must be installed for a connection station to the three-phase AC grid, even though the available power cannot be fully utilized—in the worst case, only 3.6 kW out of a possible 22 kW.

[0007] Furthermore, it proves to be a disadvantage that a single cooling device, namely a water cooling device, is provided for the entire charging device, so that in the event of a malfunction of the charging device, the entire charging device always has to be replaced.

[0008] Finally, it proves to be a disadvantage that the energy converters of the charging device must always be designed for the entire maximum battery voltage of the high-voltage battery, because if more than one energy converter is present, the energy converters are operated in parallel.

[0009] WO 2013 / 104408 A1 further discloses a charging device that provides a corresponding number of independent DC voltages via a plurality of DC / DC converters. Finally, JP 2013-81301 A discloses an energy converter with three half-bridge modules that can be switched between different energy flow directions as DC / DC converters to electrically couple a motor vehicle's drive unit to both a vehicle battery and a single-phase public power grid. EP 2815913 A1 further discloses a charging system for electric vehicles. US 2013 / 0020989 A1 further discloses an AC / DC power converter and a DC charging station. In addition, WO 2013 / 117425 A1 discloses a converter for a battery charging station.Finally, DE 10 2013 220 704 A1 discloses the dual use of an inverter for conductive and inductive charging of an electric vehicle, and US 2015 / 0 155 791 A1 discloses a power supply device and a method for generating power using the same.

[0010] Overall, the purpose of the invention is to provide an improved charging device.

[0011] The invention proposes a charging device according to claim 1, an electrically powered motor vehicle according to further independent claim 7, and a method according to further independent claim 8 as a solution.

[0012] Further advantageous embodiments of the invention will become apparent from the features of the dependent claims.

[0013] With regard to a charging device of this type, it is particularly proposed that the DC voltage connections of the charging modules be connected in series to the first connection unit.

[0014] With regard to a motor vehicle of this type, it is particularly proposed that the DC connections of the charging modules be connected in series to the electrical energy storage device.

[0015] Finally, with regard to a generic procedure, it is specifically proposed that the energy storage device be charged via the DC voltage connections connected in series.

[0016] The invention thus proposes for the first time that, on the DC side, the charging modules no longer need to be operated in parallel, but can instead be operated in series. The series connection is understood to mean that the individual DC voltages of the charging modules add up to a total voltage, and no partial compensation occurs due to reverse polarity. If exactly one charging module is connected to exactly one phase of the multi-phase AC electrical network, then all charging modules will carry the same DC current. Furthermore, if the charging modules are identical in type, it can be assumed that each charging module provides approximately the same DC voltage.This has the advantage that the charging modules no longer need to be designed for the full DC voltage dictated by the maximum battery voltage of the energy storage system, particularly the high-voltage battery. By selecting appropriate components, requirements regarding electrical safety in the design of the respective charging modules can also be simplified, resulting in cost savings.

[0017] Preferably, the charging module includes or is formed by a switched-mode power converter. The charging module may also include a rectifier unit. Alternatively, the switched-mode power converter may also provide a rectifier function. Furthermore, the charging module may also include a linear regulator, for example, to adjust a DC voltage.

[0018] Furthermore, the invention allows for a modular design of the charging device, for example, by having each charging module form a single unit that is manageable and preferably also individually testable, and can be easily detachably coupled to the charging device. This simplifies not only the manufacture of the charging device but also any maintenance and repair work. Naturally, it is also possible to connect two or more charging modules in parallel to one phase of the multi-phase AC power network, which are then also connected in parallel on the DC side. This allows for a matrix-like connection within the charging device, which permits a high degree of flexibility. In this way, charging devices with different power outputs can be provided simply by adjusting the configuration with appropriate charging modules.The invention proves particularly advantageous when used with the standard three-phase AC power grid, such as that provided by the public power supply network. On the AC side, the charging modules can be connected to the three-phase AC power grid in either a star or delta configuration. Depending on the power requirements, switching between these configurations can also be provided. Overall, this allows for a substantially uniform load distribution across the three-phase AC power grid. The active phase switching common in the prior art can be completely eliminated. At the same time, significantly higher power output can be achieved compared to prior art charging devices, which also reduces charging times for the high-voltage battery.

[0019] A multiphase AC electrical network as defined in the invention is an AC electrical network comprising at least two phases whose alternating voltages preferably have substantially the same frequency and, in particular, approximately the same amplitude, but which are phase-shifted relative to each other. In addition to the respective phases, for which corresponding phase conductors are provided, the multiphase AC electrical network typically also includes a neutral conductor. This can serve to close the circuit, particularly in the case of an unbalanced load on the multiphase AC electrical network. Depending on the operating mode, it may also be de-energized during operation. Furthermore, a protective conductor may also be provided.Multiphase AC electrical networks include, in particular, the three-phase AC electrical network, which—as previously explained—is provided by the public power grid, a four-phase AC electrical network, a five-phase AC electrical network, and / or similar networks, such as those used in specific industrial installations. Multiphase AC electrical networks are characterized, among other things, by their ability to generate rotating fields, which allow for the particularly efficient operation of rotating electrical machines. Typically, the voltage amplitude in multiphase AC electrical networks is essentially the same for each phase.Furthermore, with a symmetrical load on the multi-phase AC electrical network, it can be achieved that the neutral conductor of the multi-phase AC electrical network is essentially not subjected to electric current.

[0020] The charging module is preferably designed to be supplied with electrical energy only via the respective AC voltage connection and to provide the corresponding DC voltage at the respective DC voltage connection by converting the AC-side electrical energy supplied. Preferably, the charging modules are designed for essentially the same electrical power output. Furthermore, they are particularly advantageously designed to be mechanically essentially identical, so that they can be interchanged in virtually any way.

[0021] The invention thus provides that, corresponding to the number of phases of the multi-phase AC electrical network, at least one charging module is provided, which is connected to precisely that phase. Preferably, the switched-mode power converter is then also connected exclusively to that phase.

[0022] The preceding and following statements apply equally to the electrically powered vehicle and to the method for charging an electrical energy storage device of an electrically powered vehicle connected to the charging device.

[0023] Each charging module has a bypass diode at its DC voltage terminal. This protects the charging modules against reverse polarity in the event of dynamic processes on the DC side, such as those caused by tolerances and / or switching operations. Such a situation can occur particularly when the charging device is switched on, for example, if the DC voltage builds up at different rates at the DC voltage terminals of the charging modules. The bypass diode, which is connected to the DC voltage terminal in reverse bias during normal operation of the charging modules, thus ensures increased operational reliability, especially under dynamic conditions.

[0024] Furthermore, it is proposed that the charging device include a monitoring circuit through which the series-connected DC terminals of the charging modules are connected to the first connection unit. This monitoring circuit allows the operating states of the charging device, and in particular the charging modules, to be detected and monitored. Moreover, the monitoring circuit can electrically decouple, and specifically disconnect, the series connection of the DC terminals of the charging modules from the electrical energy storage system. This is useful, for example, if the charging device detects a fault and hazardous conditions need to be avoided. Such a condition could be caused, for instance, by a defect in a charging module or similar component. Such a defect could be, for example, an insulation fault or the like.Furthermore, the monitoring circuit can also be designed to detect reverse polarity in a connected electrical energy storage device, particularly a high-voltage battery, and prevent electrical coupling between the DC-connected charging modules and the electrical energy storage device. Additionally, it can be designed to provide electrical decoupling in the event of faults within the multi-phase AC electrical network, for example, if one or more phases fail, resulting in a highly unbalanced load on the network.One aspect of the invention is to achieve, through the circuit topology, the most uniform possible load distribution across the multiphase AC electrical network when high power is drawn from it. To this end, it is specifically provided that the charging modules are preferably operated with essentially the same electrical power. For this purpose, the charging device can include a control unit connected to the charging modules, which controls them accordingly.

[0025] Furthermore, the monitoring circuit can also monitor other parameters of the charging device, in particular the charging modules, and control corresponding changes in state, especially with regard to electrical coupling. This allows for monitoring the temperature of the charging device, including the temperature of each individual charging module, the function of a cooling device, and, if applicable, individual charging module cooling modules or similar components.

[0026] It is particularly advantageous if the monitoring circuit includes a reverse current protection diode. The reverse current protection diode is preferably connected in series with the DC voltage terminals of the charging modules, which are connected in series on the DC side, in such a way that electric current can flow during normal charging operation. The reverse current protection diode ensures that electrical energy cannot be fed from the electrical energy storage device into the charging device. This protects the charging modules from impermissible exposure to electrical energy on the DC side.For this purpose, the reverse current protection diode preferably has a reverse voltage withstand capability that exceeds the rated voltage of the electrical energy storage device by a protection factor to ensure that the voltage withstand capability of the reverse current protection diode is always sufficient in the intended operation of the charging device.

[0027] According to a further training, it is proposed that, to provide a modular design for the charging device, each charging module is designed as an individually handleable unit. This allows for a modular design of the entire charging device, enabling its simple assembly as needed. The charging modules can thus be provided and preferably also tested as separately handled units. This allows for the temporary storage of the charging modules and their assembly only when orders for the respective charging device are received. Because the charging modules are individually handled units, they can be arranged in virtually any configuration within the charging device. Furthermore, the appropriate selection of connection units, particularly plug connectors, ensures easy assembly.Furthermore, this design naturally allows for very simple maintenance of a charging device in the event of a malfunctioning charging module. The faulty charging module can easily be replaced with another charging module, particularly one that has already been tested for functionality. This can be done quickly, thus improving the overall availability of the charging device.

[0028] Preferably, each charging module also has its own cooling unit enclosed within its assembly. This further improves the modular design of the charging device, especially when the charging modules include their own cooling units. It is particularly advantageous if the charging device includes a cooling system that thermally couples the cooling units of the charging modules and reliably dissipates the heat energy from the charging modules. For this purpose, the cooling units can, for example, include a cooling plate that contacts a corresponding contact surface of the cooling system on the charging device side. The contact surface of the charging device can be equipped, for example, with air cooling, water cooling, and / or the like to dissipate the heat. For the purpose of thermal coupling, the cooling plates can be pressed against the corresponding contact surfaces on the charging module side.

[0029] According to a further training, it is proposed that the charging modules be designed to provide essentially the same DC voltage. This would allow for the use of essentially identical charging modules in the construction of the charging device. Furthermore, this would also enable standardization of the charging modules, thus improving the overall modular design of the charging device. Standardization would also allow for the creation of different charging devices for varying power requirements simply by arranging the appropriate number of charging modules in each device. Additionally, the manufacturing of the charging modules could be more cost-effective because standardization would allow for mass production and, in particular, testing.

[0030] To adapt the charging device to different electrical energy storage devices with regard to the DC operating voltage, it is particularly proposed that at least one of the charging modules be operated in a current-controlled manner and the other charging modules in a voltage-controlled manner. This allows the DC voltage supplied to the first connection unit for the electrical energy storage device to be adjusted as needed, thereby ensuring that the electrical energy storage device is supplied with an electric current for charging purposes in a predefinable manner. The electric current can, for example, depend on the type of electrical energy storage device, its charge capacity, its state of charge, and / or similar factors.In particular, this is a parameter specified by the manufacturer, which is implemented by means of the charging device in order to charge the electrical energy storage device as optimally as possible, to achieve the fastest possible charging, to achieve the longest possible service life of the electrical energy storage device and / or the like.

[0031] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the figures. In the figures, the same reference numerals denote the same features and functions.

[0032] They show: Fig. 1 A schematic block diagram of a prior art charging device connected to a three-phase AC electrical network on the AC side, with two charging modules connected in parallel to a high-voltage battery on the DC side; and Fig. 2 a charging device according to the invention, which is connected to a three-phase alternating current electrical network on the alternating current side and which has a charging module for each phase, which are connected in parallel on the direct current side to a high-voltage battery of a motor vehicle.

[0033] Fig. Figure 1 shows a charging device 10 according to the prior art, as it is currently commonly used. The charging device 10 has a first connection unit 16, which is connected to an electrical energy storage device 14, which in this case is formed by a high-voltage battery of a motor vehicle (not shown). The motor vehicle has an electric drive unit (also not shown) that uses the high-voltage battery 14 for propulsion.

[0034] Furthermore, the charging device 10 has a second connection unit 18, which is connected to a three-phase alternating current electrical network 12, here the public power supply network. From the Fig. It is not apparent from Figure 1 that the second connection unit 18 has exactly one connection element for each phase P1, P2, P3 of the three-phase AC electrical network 12. Each connection element is thus electrically coupled to exactly one of the phases P1, P2, P3. Furthermore, the charging device 10 has a connection for a neutral conductor N and a connection for a protective conductor S of the three-phase AC electrical network 12.

[0035] The charging device 10 further comprises a charging module 22 and a charging module 24, each configured as a switched-mode power converter and having a single-phase AC input connected to the three-phase AC electrical network 12 via an active phase switch 20. On the DC side, the charging modules 22 and 24 are connected in parallel to the first connection unit 16.

[0036] The charging modules 22 and 24 are arranged in a common assembly. To reduce phase imbalance, active phase switching 20 is provided, by means of which the charging modules 22 and 24 are connected to the respective phases P1, P2, and P3 of the three-phase AC electrical network 12 in a predefinable manner. This is intended, among other things, to ensure compliance with the low-voltage directive VDE-AR-N 4105. The charging device 10 is available with a power output of 3.6 kW or 7.2 kW. At the 7.2 kW power output, active phase switching 20 is required to avoid phase imbalance.

[0037] Although the charging device 10 has proven itself in the prior art, it requires a complex power module in the form of an active phase switch 20. This precludes a modular design due to inherent structural limitations. Furthermore, the power supplied by the three-phase AC power grid 12 cannot be fully utilized, as only 3.6 kW or 7.2 kW are possible. However, the three-phase AC power grid 12, in the form of the public low-voltage power supply network, allows for the provision of either 11 kW or 22 kW, depending on the connection type. Corresponding connections are designed, for example, for a nominal current load of 16 amperes or 32 amperes.Furthermore, the charging device 10 proves to be disadvantageous in that, in the event of a malfunction, the entire charging device 10 must always be replaced or serviced. Finally, the charging modules 22, 24 must always be designed for the entire operating voltage of the high-voltage battery 14 because the charging modules 22, 24 are operated in parallel.

[0038] This problem can be remedied by means of the invention. Fig. Figure 2 shows a corresponding charging device 30 according to the invention, which also has a first connection unit 16 connected to the electrical energy storage device 14. Furthermore, the charging device 30 also has a second connection unit 18 connected to the three-phase AC electrical network 12 and – as in the embodiment according to Figure 2 – Fig. 1 - has one connection element each for phase P1, P2, P3 as well as for the neutral conductor N and the protective conductor S of the multi-phase AC electrical network 12. In this respect, with regard to the external connection options, the charging device 30 largely corresponds to the charging device 10.

[0039] However, the design of the charging device 30 is now different. Unlike the design according to Fig. 2 is in the embodiment according to the invention according to Fig. 2. Now, exactly one charging module 32, 34, 36 in the form of a switched-mode power converter is provided for each phase P1, P2, P3 of the three-phase AC electrical network 12. Each of the charging modules 32, 34, 36 has exactly one AC voltage connection 56, 58, 60, which serves to supply a single-phase AC voltage. They are connected in a star configuration on the AC side. Each of the charging modules 32, 34, 36 also has a DC voltage connection 62, 64, 66 for providing a DC voltage. The respective AC voltage connection 56, 58, 60 is connected to the connection element of the phase P1, P2, P3 of the three-phase AC electrical network 12 assigned to the charging module 32, 34, 36. Each of the charging modules 32, 34, 36 is further connected to a control unit of the charging device 30 which is not shown.The control unit can be used to activate or deactivate charging modules 32, 34, and 36. Furthermore, parameters such as voltage, current, and / or similar can be set. Finally, the control unit also records the temperature of each charging module for temperature monitoring purposes.

[0040] According to the invention, the DC voltage connections 62, 64, 66 of the charging modules 32, 34, 36 are connected in series to the first connection unit 16. In this case, the connection is made via a monitoring circuit 44, which has an electromechanical switching element in the form of a switching contact 46. Furthermore, the monitoring circuit 44 includes a reverse current protection diode 48, which is also connected in series with the series connection of the DC voltage connections 62, 64, 66. The reverse current protection diode 48 prevents the high-voltage battery 14 from feeding electrical energy into the charging device 30 in an undesired manner, which could lead to damage within the charging device 30, particularly with regard to the charging modules 32, 34, 36. The monitoring circuit 44 is also connected to the control unit.

[0041] The monitoring circuit 44 monitors the electrical voltage at the first terminal unit 16 as well as the temperature of the charging modules 32, 34, 36. Furthermore, the electrical current flowing through the first terminal unit 16 is also monitored by means of a current sensor (not shown). Additionally, the electrical voltage of phases P1, P2, P3 and the electrical current in these phases are monitored. If impermissible conditions occur, the electromechanical switching element 46 opens the DC circuit, thus interrupting the current flow through the first terminal unit 16.

[0042] Furthermore, the charging device 30 has a bypass diode 50, 52, 54 on the DC side for each of the charging modules 32, 34, 36. The bypass diodes 50, 52, 54 serve to prevent reverse polarity on the DC side at the DC terminals 62, 64, 66 during dynamic processes, especially when the charging device 30 is switched on. This protects the charging modules 32, 34, 36 from reverse polarity.

[0043] The present design according to Fig. Furthermore, paragraph 2 allows the charging device 30 to be designed to provide a modular structure. In this case, each of the charging modules 32, 34, 36 is designed as an individually handleable unit. This allows each charging module to be easily arranged or replaced individually during manufacturing and maintenance. A particularly advantageous feature is the provision of electrical connectors for the electrical connections, thus reducing the need for complex assembly work.

[0044] Furthermore, each of the charging modules 32, 34, 36 has its own cooling unit 38, 40, 42 in the form of a cooling plate. The cooling unit 38, 40, 42 is each enclosed within the assembly of the charging module 32, 34, 36. This allows the manageable assembly to encompass not only the charging module but also its cooling system in a suitable manner. This makes it possible to test individual charging modules 32, 34, 36 independently of operation in the charging device 30. The cooling plates 38, 40, 42 contact a corresponding, in Fig. 2 Contact surface of the charging device 30 (not shown). The cooling plates 38, 40, 42 serve to dissipate heat energy generated during the conversion process in the charging modules 32, 34, 36.

[0045] For this purpose, the cooling plates 38, 40, 42 are thermally coupled to corresponding contact surfaces of the charging device 30, so that the thermal energy can be dissipated via this connection. The charging device 30 has a cooling system (not shown in detail) that is thermally coupled to the contact surface and is implemented here by air cooling. Alternatively or additionally, liquid cooling, for example using a coolant such as water or the like, can also be provided.

[0046] Furthermore, it is provided that the charging modules 32, 34, 36 are designed to provide essentially the same DC voltage. This allows the charging modules 32, 34, 36 to be standardized, simplifying both manufacturing and maintenance. Moreover, the series connection on the DC side means that the charging modules 32, 34, 36 no longer need to be designed for the entire operating voltage of the high-voltage battery 14. This reduces the effort required for electrical safety.

[0047] To enable adaptation to the high-voltage battery 14, the charging module 36 is designed to operate in current-controlled mode, while charging modules 32 and 34 are operated in voltage-controlled mode. This allows for voltage adjustment within the control range, while the current control simultaneously enables the high-voltage battery 14 to be supplied with electrical current for charging in a predefined manner. This allows for highly flexible adjustment of the electrical parameters with respect to the high-voltage battery 14, thus achieving optimal charging, for example, with regard to charging speed, maximum service life, and / or similar factors. Since all charging modules 32, 34, and 36 are supplied with the same direct current on the DC side, highly flexible adjustment is possible.

[0048] Preferably, the charging modules 32, 34, 36 are controlled by the control unit of the charging device 30 (not shown) such that they convert essentially the same electrical power. This ensures that the three-phase AC electrical network 12 is subjected to a substantially symmetrical load on the AC side. The phase misalignment frequently encountered in the prior art can thus be largely avoided, or at least reduced.

[0049] The active phase switching 20 required in the prior art can be completely eliminated by the invention. Furthermore, the invention enables the charging device 30 to have a modular design. The advantages discussed previously can thus be achieved. In addition, the monitoring circuit 44 ensures a high level of safety, particularly with regard to the charging device 30, but also with regard to the connected equipment such as the high-voltage battery 14 and the AC power grid 12. The monitoring circuit 44 is specifically designed to shut down the entire charging device 30 even if only one of the charging modules 32, 34, 36 malfunctions. Furthermore, the cooling plates 38, 40, 42 of the charging device 30 can be thermally connected in series.This allows thermal equalization to occur between the charging modules 32, 34, 36.

[0050] The exemplary embodiment serves only to illustrate the invention and is not limiting to it. Furthermore, it should be noted that the advantages, features, and embodiments described for the device according to the invention apply equally to the corresponding method and vice versa. In particular, corresponding method features may be provided for device features and vice versa.

Claims

[1] Charging device (30) for charging an electrical energy storage device (14) of an electrically powered motor vehicle that can be connected to the charging device (30), comprising: - a first connection unit (16) for connecting to the electrical energy storage device (14), - a second connection unit (18) for connection to a multi-phase AC electrical network (12), with one connection element for each phase of the multi-phase AC electrical network (12), - exactly one charging module (32, 34, 36) per phase of the multi-phase AC electrical network (12), wherein each of the charging modules (32, 34, 36) has a respective AC voltage connection (56, 58, 60) for supplying a single-phase AC electrical voltage and a respective DC voltage connection (62, 64, 66) for providing a DC electrical voltage, wherein the AC voltage connection (56, 58, 60) is connected to the connection element of the phase (P1, P2, P3) of the multi-phase AC electrical network (12) assigned to the charging module (32, 34, 36), wherein the DC voltage connections (62, 64, 66) of the charging modules (32, 34, 36) are connected in series to the first connection unit (16), wherein each of the charging modules (32, 34, 36) is connected at its The DC voltage connection (62, 64, 66) has a bypass diode (50, 52, 54). [2] Charging device according to claim 1, characterized bya monitoring circuit (44) via which the series-connected DC voltage terminals (62, 64, 66) of the charging modules (32, 34, 36) are connected to the first connection unit (16). [3] Charging device according to claim 2, characterized by that the monitoring circuit (44) has a reverse current protection diode (48). [4] Charging device according to any one of claims 1 to 3, characterized by , that to provide a modular structure of the charging device (30) each of the charging modules (32, 34, 36) is designed as an individually handleable unit. [5] Charging device according to claim 4, characterized by , that each of the charging modules (32, 34, 36) has its own cooling unit (38, 40, 42) which is enclosed by its assembly unit. [6] Charging device according to one of the preceding claims, characterized by , that the charging modules (32, 34, 36) are designed to provide essentially the same DC electrical voltage. [7] Electrically powered motor vehicle with an electrical system comprising an electrical energy storage device (14) and a drive unit connected to the electrical system, wherein the electrical system comprises a charging device (30) connected to the electrical energy storage device (14) for charging the electrical energy storage device (14), comprising: - a connection unit (18) for connection to a multi-phase alternating current electrical network (12), which has one connection element for each phase of the multi-phase alternating current electrical network (12), - exactly one charging module (32, 34, 36) per phase of the multiphase AC electrical network (12), wherein each of the charging modules (32, 34, 36) has a respective AC voltage connection (56, 58, 60) for supplying a single-phase AC electrical voltage and a respective DC voltage connection (62, 64, 66) for providing a DC electrical voltage, wherein the AC voltage connection (56, 58, 60) is connected to the connection element of the phase (P1, P2, P3) of the multiphase AC electrical network (12) assigned to the charging module (32, 34, 36), wherein the DC voltage connections (62, 64, 66) of the charging modules (32, 34, 36) are connected in series to the electrical energy storage device (14), wherein each of the charging modules (32, 34, 36) is connected at its The DC voltage connection (62, 64, 66) has a bypass diode (50, 52, 54). [8] Method for charging an electrical energy storage device (14) of an electrically powered motor vehicle connected to a charging device (30), wherein the charging device (30) is supplied with electrical energy from a multi-phase AC electrical network (12) by connecting exactly one charging module (32, 34, 36) with a respective AC voltage connection (56, 58, 60) to each phase (P1, P2, P3) of the multi-phase AC electrical network (12), wherein a single-phase AC electrical voltage from the multi-phase AC electrical network (12) is supplied to the charging module (32, 34, 36) via its respective AC voltage connection (56, 58, 60), wherein each charging module (32, 34, 36) provides a DC electrical voltage at a respective DC voltage connection (62, 64, 66) by converting the AC-side supplied electrical energy,wherein the energy storage device (14) is charged via the DC voltage terminals (62, 64, 66) of the charging modules (32, 34, 36) connected in series, each of the charging modules (32, 34, 36) having a bypass diode (50, 52, 54) at its DC voltage terminal (62, 64, 66). [9] Method according to claim 8, characterized by , that at least one of the charging modules (32, 34, 36) is current-controlled and the other charging modules (32, 34, 36) are voltage-controlled.

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