DE102019204805A1 - DC power supply device and method for charging a battery, in particular a battery of an electric motor vehicle - Google Patents

Abstract

The present invention provides a DC power supply device and a method for charging a battery, in particular a battery of an electric motor vehicle. The DC voltage network device is equipped with a first potential generating device (a) which is connectable on the primary side to a supply network (V) and which is configured on the secondary side for outputting a first potential (V1) to a first supply line (La); a second potential generating device (b), which on the primary side of the supply network (V) can be connected and which on the secondary side for outputting a second potential (V2) to a second supply line (Lb) is configured; a third potential generating device (c), which is connectable on the primary side to the supply network (V) and which is configured on the secondary side for outputting a third potential (V3) to a third supply line (Lc); a plurality of charging terminals (V1-V5; V1-V5; V4 ', V5`) for charging a battery (B1-B5; B1-B5; B4`, B5`) electrically connected thereto; the charging connections (V1-V5; V1-V5; V4 ', V5') having a first group (V1, V4, V5; V1, V4, V5, V4 ', V5') which are connected via a respective switching device (S1, S4, S5, S1, S4, S5, S4 ', S5') is connectable to the first supply line (La) and the second supply line (Lb) for outputting a first charging voltage (U1); the charging connections (V1-V5, V1-V5, V4 ', V5') having a second group (V2, V4, V5, V2, V4, V5, V4 ', V5') which are connected via a respective switching device (S2, S4, S5, S2, S4, S5, S4 ', S5') is connectable to the second supply line (Lb) and the third supply line (Lc) for outputting a second charging voltage (U2); and wherein the charging terminals (V1-V5; V1-V5; V4 ', V5') have a third group (V3, V4, V5; V3, V4, V4, V4 ', V5') connected via a respective switching device (S3 , S4, S5, S3, S4, S5, S4 ', S5') to the first supply line (La) and the third supply line (Lc) for outputting a third charging voltage (U3) is connectable.

Description

The present invention relates to a DC power supply device and a method for charging a battery, in particular a battery of an electric motor vehicle.

State of the art

Although applicable to any batteries, the present invention and its underlying problem will be explained with reference to a battery of an electric motor vehicle.

In order for electric motor vehicles to develop from the pure city vehicle to the vehicle for all routes and thus to develop from the second vehicle to the first vehicle, a reliable and modern charging infrastructure is required. The more electric vehicles are on the road, the more power is needed to charge the batteries of all these electric vehicles. A profitable operation of charging stations in the next few years can only be done in the urban area. In rural areas, grid expansion will not be as fast as charging stations will be.

Only with high investments and intelligent technology can the power grids be strengthened in such a way that the required power is available to charge the electric charging vehicles at the public charging stations. If many electric vehicles are charged at the same time or charge their batteries at the fast charging stations, high peak loads occur at these local locations. In addition, the network load spread over the day varies. In this regard, the public power grid is far from optimally designed today. This is why energy utilities are increasingly focusing on electricity generation, electricity consumption and energy storage, and are aiming for decoupling over time so that, for example, solar power can also be used at night.

Today's fast charging stations typically use AC / DC converters, such as from the WO 2012/038222 A2 known.

The batteries of electric vehicles differ technically in many respects, especially with regard to cell types, voltage levels and voltage ranges. The batteries need to be constantly recharged, which requires charging stations and chargers integrated into the electric vehicle. The electrical energy transmission from the power plant to the consumer usually takes place via an AC voltage network. In order to charge a DC storage in the form of a battery from the AC mains, the voltage form must be converted. This conversion is done by an AC converter (AC / DC converter). The minimum and maximum output power of the AC converter depends on the amplitude of the AC voltage and the type of converter. If, for example, the minimum voltage of such a converter is 650 V, an additional DC converter (DC / DC converter) is required to charge a battery with 400 V battery voltage. For example, if the voltage of the converter is 400 V, an expensive DC converter (DC / DC converter) is also required to charge a battery with 800 V battery voltage. In order to increase the efficiency and reduce the cost, it is preferred that a converter of the type boost converter or step-down converter is used.

Disclosure of the invention

The present invention provides a DC power supply device and a method for charging a battery, in particular a battery of an electric motor vehicle according to independent claims 1 and 12, respectively.

Advantages of the invention

The DC power supply device and the method according to the present invention make it possible to reduce or eliminate restrictions with regard to desired charging power and network stability and to construct the charging station with a charging station as flexibly as possible.

The idea underlying the present invention is to allow a simultaneous charging of a plurality of batteries with different charging voltages, which can be tapped off by an at least three-phase DC network.

Preferred developments are the subject of the respective subclaims.

According to a preferred embodiment, the charging terminals have a fourth group, which via a respective switching device alternatively with either the first supply line and the second supply line for outputting the first charging voltage or with the second supply line and the third supply line for outputting the second charging voltage or with the first Supply line and the third supply line for outputting the third charging voltage is connectable. This allows various charging voltages to be switchably provided at a charging port.

According to a further preferred embodiment, a DC voltage converter device for converting the corresponding charging voltage into a DC charging voltage of the battery is connected between at least one charging connection and the associated switching device. This increases the flexibility.

According to a further preferred embodiment, an alternating voltage converter device for converting the corresponding charging voltage into a charging AC voltage of the battery is connected between at least one charging connection and the associated switching device. This allows the connection of inductively rechargeable batteries.

According to a further preferred embodiment, at least one storage capacitor is connected between one of the first to third supply lines and a further one of the first to third supply lines. This makes it possible to counteract voltage fluctuations.

According to a further preferred embodiment, at least one net damper device is provided for stabilizing and / or vibration damping and / or damping the net. This increases the network stability.

According to another preferred embodiment, the first, second and third potentials are different from each other. This increases the number of available charging voltages.

According to a further preferred embodiment, the first switching element is arranged between a first supply line and a node. The first switching element may be an on / off element. A second switching element may electrically couple a first terminal of a charging station to either the second supply line or the node. A third switching element may couple a second terminal of the charging station to either the third supply line or the node. According to a further preferred embodiment, a diode is arranged between the first terminal of the charging station and the second switching element and / or between the second terminal of the charging station and the third switching element.

According to a further preferred embodiment, the charging connections are two-pole or three-pole.

According to a further preferred embodiment, an energy management device is provided, by means of which the fourth switching device can be controlled, wherein the energy management device is designed to detect a state of charge of the battery and to control the switching device of the fourth group as a function of the detected state of charge of the battery. This enables efficient energy management based on predefined or predefinable criteria.

According to a further preferred embodiment, the energy management device is designed such that the control of the fourth switching device in dependence on the detected state of charge of the battery is such that is switched with increasing state of charge of the battery from a lower to a higher charging voltage. This increases the flexibility and allows adaptation to existing buck-boosters or boosters.

According to a further preferred embodiment, the energy management device is designed such that the control of the fourth switching device in response to the detected state of charge of the battery is such that is switched with increasing state of charge of the battery from a higher to a lower charging voltage. This increases the flexibility and allows adaptation to existing buck-boosters or boosters.

list of figures

• 1 eine schematische Darstellung zur Erläuterung einer Gleichspannungs-Netzvorrichtung zum Laden einer Batterie eines Elektrokraftfahrzeuges gemäß einer ersten Ausführungsform der vorliegenden Erfindung;
• 2 eine schematische Darstellung zur Erläuterung einer Gleichspannungs-Netzvorrichtung zum Laden einer Batterie eines Elektrokraftfahrzeuges gemäß einer zweiten Ausführungsform der vorliegenden Erfindung;
• 3 eine schematische Darstellung zur Erläuterung einer Gleichspannungs-Netzvorrichtung zum Laden einer Batterie eines Elektrokraftfahrzeuges gemäß einer dritten Ausführungsform der vorliegenden Erfindung;
• 4 eine schematische Darstellung zur Erläuterung einer Gleichspannungs-Netzvorrichtung zum Laden einer Batterie eines Elektrokraftfahrzeuges gemäß einer vierten Ausführungsform der vorliegenden Erfindung;
• 5 eine schematische Darstellung zur Erläuterung einer Gleichspannungs-Netzvorrichtung zum Laden einer Batterie eines Elektrokraftfahrzeuges gemäß einer fünften Ausführungsform der vorliegenden Erfindung;
• 6 eine schematische Darstellung zur Erläuterung einer Gleichspannungs-Netzvorrichtung zum Laden einer Batterie eines Elektrokraftfahrzeuges gemäß einer sechsten Ausführungsform der vorliegenden Erfindung;
• 7 eine schematische Darstellung zur Erläuterung einer Schalteinrichtung für eine Gleichspannungs-Netzvorrichtung gemäß einer Ausführungsform;
• 8 eine schematische Darstellung zur Erläuterung einer Schalteinrichtung für eine Gleichspannungs-Netzvorrichtung gemäß einer alternativen Ausführungsform; und
• 9 eine schematische Darstellung zur Erläuterung einer Schalteinrichtung für eine Gleichspannungs-Netzvorrichtung gemäß einer weiteren alternativen Ausführungsform.

Show it:

• 1 a schematic illustration for explaining a DC power supply device for charging a battery of an electric motor vehicle according to a first embodiment of the present invention;
• 2 a schematic representation for explaining a DC power supply device for charging a battery of an electric motor vehicle according to a second embodiment of the present invention;
• 3 a schematic illustration for explaining a DC power supply device for charging a battery of an electric motor vehicle according to a third embodiment of the present invention;
• 4 a schematic illustration for explaining a DC power supply device for charging a battery of an electric motor vehicle according to a fourth embodiment of the present invention;
• 5 a schematic representation for explaining a DC power supply device for charging a battery of an electric motor vehicle according to a fifth embodiment of the present invention;
• 6 a schematic illustration for explaining a DC power supply device for charging a battery of an electric motor vehicle according to a sixth embodiment of the present invention;
• 7 a schematic illustration for explaining a switching device for a DC power supply device according to an embodiment;
• 8th a schematic illustration for explaining a switching device for a DC power supply device according to an alternative embodiment; and
• 9 a schematic representation for explaining a switching device for a DC power supply device according to another alternative embodiment.

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

Description of the embodiments

1 FIG. 12 is a schematic diagram for explaining a DC power supply apparatus for charging a battery of an electric motor vehicle according to a first embodiment of the present invention. FIG.

The three-phase DC power supply N1 for charging a battery of an electric motor vehicle is equipped with a first potential generating means a , which primary side to a supply network V can be connected or connected and which secondary side for outputting a first potential V1 to a first supply line La is configured.

Furthermore, a second potential generating device is provided b , which are connected to the supply network on the primary side V can be connected or connected and which secondary side for outputting a second potential V2 to a second supply line lb is designed.

Finally, a third potential generating device c provided, which primary side to the supply network V can be connected or connected and which secondary side for outputting a third potential V3 to a third supply line Lc is designed.

A plurality of first to fifth charging ports V1 - V5 is used to charge a respective first to fifth battery electrically connected thereto B1 - B5 a (not shown) electric motor vehicle.

The charging ports have a first group of charging ports V1 . V4 . V5 on, each of a first, fourth and fifth switching device S1 . S4 . S5 with the first supply line La and the second supply line Lb for outputting a first charging voltage U1 is connectable.

The charging ports have a second group of charging ports V2 . V4 . V5 on, each of a second, the fourth and the fifth switching device S2 . S4 . S5 with the second supply line lb and the third supply line Lc for outputting a second charging voltage U2 is connectable.

The charging ports have a third group of charging ports V3 . V4 . V5 , each with a third, the fourth and the fifth switching device S3 . S4 . S5 with the first supply line La and the third supply line Lc for outputting a third charging voltage U3 is connectable.

Characterized in that the fourth and fifth switching means have a multiple switching function, overlap the first to third group of the charging terminals V1 - V5 , In other words, the charging terminals have a fourth group of charging terminals V4 . V5 on, which also belong to the first and second group.

The fourth and fifth switching device S4 . S5 allow the fourth or fifth charging port V5 respectively. V5 alternatively alternatively with the first supply line La and the second supply line lb for outputting the first charging voltage U1 or with the second supply line lb and the third supply line Lc for outputting the second charging voltage U2 or with the first supply line La and the third supply line Lc for outputting the third charging voltage U3 is connectable.

In the first embodiment, for example, the first charging voltage U1 = 300 V , the second charging voltage U2 = 400 V and the third charging voltage U3 = 700 V, wherein the first to third charging port V1 - V3 bipolar and the fourth and fifth charging ports V4 . V5 can be switched three poles.

So if an electric motor vehicle with a battery voltage of 350 V with a DC-DC converter, which can only increase the charging voltage of the charging port, it is forcibly at the first charging station V1 or the fourth charging station V4 or the fifth charging station V5 to load.

If another electric motor vehicle with a battery voltage of 350 V with a DC-DC converter, which can only lower the charging voltage of the charging port, it is at the second charging station V2 or the third charging station V3 (as far as the dielectric strength is greater than the third charging voltage U3 is) or the fourth charging station V4 or the fifth charging station V5 to load.

If there is another electric vehicle with a battery voltage of 800 V with a DC-DC converter, which can only increase the charging voltage of the charging port, it can be used at all charging stations V1 - V5 getting charged.

An electric motor vehicle with a battery voltage of 400 V, wherein the battery voltage range is between 330 V at a charge state of 1% and 450 V at a charge state of 100%, with a boost converter is at the fourth charging station V4 connected.

If the electric vehicle has a charge state of 1% (battery voltage 330 V) on arrival, it can first with the first charging voltage U1 = 300V are charged until the battery voltage rises above 400V. From this moment until the vehicle battery is fully charged, it can be charged either with the first charging voltage U1 = 300 V or second charging voltage U2 = 400 V.

Which of the latter two options is selected can be automatically determined by an energy management system (cf. 6 ).

Another electric motor vehicle with a battery voltage of 800 V, wherein the battery voltage range between 650 V in a state of charge of 1% and 850 V at a state of charge of 100%, with a boost converter is now at the fourth charging station V4 connected.

If the other electric vehicle on arrival has a state of charge of 1% (battery voltage 650 V), it can first be charged with the first charging voltage U1 = 300 V or the second charging voltage U2 = 400 V until the battery voltage rises above 700 V. From this moment until the vehicle battery is fully charged, it can be charged either with the first charging voltage U1 = 300 V or second charging voltage U2 = 400 V or the third charging voltage U3 = 700 V.

As in the previous case, due to predetermined energy management criteria and possible further criteria, this can be done automatically by an energy management system (cf. 6 ).

2 FIG. 12 is a schematic diagram for explaining a DC power supply apparatus for charging a battery of an electric motor vehicle according to a second embodiment of the present invention. FIG.

The DC power supply device N2 according to the second embodiment differs from the first embodiment described above in that between the first to fifth charging port V1 - V5 and the associated first to fifth switching device S1 - S5 a respective first to fifth DC voltage converter means W1 - W5 for converting the corresponding charging voltage U1 . U2 . U3 in a DC charging voltage of the respective first to fifth battery B1 - B5 is switched.

3 FIG. 12 is a schematic diagram for explaining a DC power supply apparatus for charging a battery of an electric motor vehicle according to a third embodiment of the present invention. FIG.

The DC power supply device N3 according to the third embodiment differs from the first embodiment described above in that a first storage capacitor CA between the first supply line La and the second supply line lb is switched and a second storage capacitor CB between the second supply line lb and the third supply line lb is switched.

A third storage capacitor C1 is parallel to the first switching device S1 at the charging port V1 connected. A fourth storage capacitor C4a is at the fourth charging port V4 between the connections of the fourth switching device S4 with the first and second supply lines La . lb connected. A fifth storage capacitor c4b is at the fourth charging port V4 between the connections of the fourth switching device S4 with the second and third supply line lb . Lc connected.

Such storage capacitors CA . CB . C1 . C4a . c4b are used for buffering voltage fluctuations of the DC voltage network, which, for example, when connecting additional vehicles or by voltage fluctuations of the supply network V can arise. The arrangement and interconnection of such storage capacitors CA . CB . C1 . C4a . c4b and possible further storage capacitors is in principle arbitrary and here only as an example.

4 is a schematic diagram for explaining a DC power supply device for charging a battery of a Electric motor vehicle according to a fourth embodiment of the present invention.

The DC power supply device N4 according to the fourth embodiment differs from the first embodiment described above in that a net damper device ND is provided, which with the first, second and third supply line La . lb . Lc is connected and is provided for stabilizing and / or vibration damping and / or damping of the network.

5 FIG. 12 is a schematic diagram for explaining a DC power supply apparatus for charging a battery of an electric motor vehicle according to a fifth embodiment of the present invention. FIG.

The DC power supply device N5 According to the fifth embodiment, a combination of the first and second embodiments.

There are seven charging stations V1 - V5 and V4 ' . V5` intended. At the first and second charging station V1 . V2 are DC-DC converters W1 . W2 intended. Likewise, at the fourth charging station V4 and the fifth charging station V5 DC voltage converter W4 respectively. W5 intended. The third, sixth and seventh charging station V3 . V4` and V5` have no DC-DC converter.

6 FIG. 12 is a schematic diagram for explaining a DC power supply apparatus for charging a battery of an electric motor vehicle according to a sixth embodiment of the present invention. FIG.

In the N6 according to the sixth embodiment, unlike the fifth embodiment, an energy management device EM provided by the fourth, fifth, sixth and seventh switching device S4 . S5 . S4 ' . S5` are automatically switchable.

For switching, a state of charge of the respective connected battery is detected B4 . B5 . B4 ' . B5` through the energy management device EM , Controlling the switching devices S4 . S5 . S4 ' . S5` then takes place as a function of the detected state of charge of the respective battery B4 . B5 . B4 ' . B5 ' ,

For example, the control could be such that with increasing state of charge of the respective battery B4 . B5 . B4 ' . B5 ' is switched from a low to a higher charging voltage. However, in individual cases, this depends on whether a boost converter or buck converter or no actuator is present in the vehicle.

Although the present invention has been fully described above with reference to preferred embodiments, it is not limited thereto but is modifiable in a variety of ways.

In particular, the various embodiments with respect to the electrical interconnection of the DC voltage with the charging stations, switching devices and the converter devices can be combined with each other. Any charging connections of the mentioned different charging variants can be connected mixed to the DC voltage network.

Non-illustrated contactors and disconnectors can be completely and / or partially integrated into the power supply or in the charging station. Also, the number of charging ports is arbitrary.

Although DC charging of the batteries is performed in the above-described embodiments, the present invention is also applicable to AC charging, wherein between the charging terminals and the associated switching means, an AC / DC converter for converting the charging voltage into a charging AC voltage of the battery is to be inserted, ie in particular for inductive charging.

Optionally, additional switching devices may be inserted between the AC to DC converters. Likewise, the voltage levels additionally provided converter can be chosen arbitrarily.

Current voltage measuring sensors and / or fuses, not shown, can be interconnected independently of one another at any point.

Although the present invention has been explained with reference to a three-phase DC network, it is not limited thereto, but applicable to any three-phase and multi-phase DC networks.

Also, the potential position of the supply lines is selected by way of example in the above-mentioned embodiments and can generally be configured as desired.

The converter device W5 can instead of switchable, alternatively, simultaneously with all supply lines La . lb, Lc be connected when a corresponding multi-pole converter device is used.

7 shows a schematic representation of the fourth switching device S4 as shown, for example, in a DC power supply device N1 - N6 the above-described first to sixth embodiments can be used. The fourth switching device S4 includes four switching elements in this example S4a . S 4 b . S4c and s4d , The first switching element S4a is between the first supply line La and a first terminal of the fourth charging station V4 arranged. The second switching element S 4 b is between the second supply line lb and the first terminal of the fourth charging station V4 arranged. The third switching element S4c is between the second supply line lb and a second terminal of the fourth charging station V4 arranged. The fourth switching element s4d is between the third supply line Lc and the second terminal of the fourth charging station V4 arranged. In this way, a flexible interconnection of the two charging terminals of the fourth charging station V4 with the three supply lines La . lb and Lc possible.

For example, are the first switching element S4a and the third switching element S4c closed and the second switching element S 4 b and the fourth switching element s4d open, so is the fourth charging station V4 the first charging voltage U1 at. Are the second switching element S 4 b and the fourth switching element s4d closed, and the first switching element S4a and the third switching element S4c open, so is the fourth charging station V4 the second charging voltage U2 at. Are the first switching element S4a and the fourth switching element s4d closed and the second switching element S 4 b and the third switching element S4c open, so is the fourth charging station V4 the third charging voltage U3 at. Are all four switching elements S4a to s4d open, so is the fourth charging station V4 completely from the supply lines La to Lc separated.

8th shows a schematic representation of a fourth switching device S4 according to an alternative embodiment. The fourth switching device S4 This embodiment differs from the fourth switching device described above S4 in that instead of four switching elements S4a to s4d only three switching element S4e to s4g are provided. In the first switching element S4e and the third switching element s4g according to 8th these are changeover switches. In the second switching element S4f according to 8th it is an on / off element.

The second switching element S4f according to 8th is between the second supply line lb and a node K arranged. The first switching element S4e according to 8th is with a connection to the first terminal of the fourth charging station V4 connected. Furthermore, the first switching element S4e according to 8th between an electrical connection to the first supply line La and an electrical connection to the node K switch back and forth. Analogously, the third switching element according to 3 is with a connection to the second terminal of the fourth charging station V4 connected. Furthermore, the third switching element s4g according to 8th between an electrical connection to the third supply line Lc and an electrical connection to the node K switch back and forth.

Accordingly, by the configuration according to 8th the following switching states are set: Connects the first switching element S4e the first connection of the fourth charging station V4 with the first supply line La and connects the third switching element s4g the second port of the fourth charging station V4 with the node K and is still the second switching element S4f closed, so is the fourth charging station V4 the first charging voltage U1 at. Connects the first switching element S4e the first connection of the fourth charging station V4 with the node K and connects the third switching element s4g the second port of the fourth charging station V4 with the third supply line Lc and is still the second switching element S4f closed, so is the fourth charging station V4 the second charging voltage U2 at. Connects the first switching element S4e the first connection of the fourth charging station V4 with the first supply line La and connects the third switching element s4g the second port of the fourth charging station V4 with the third supply line Lc , so is the fourth charging station V4 the third charging voltage U3 at. In the latter case is still the second switching element S4f preferably opened.

9 shows a schematic representation of a fourth switching device S4 according to a further alternative embodiment. The fourth switching device S4 This embodiment differs from the fourth switching device described above S4 according to 8th in that in addition between the node K and a terminal of the fourth charging station V4 a diode D is provided. In this way it can be ensured that the electric current only in the intended direction, ie from the supply lines La . lb and Lc in the direction of the fourth charging station V4 flows. Especially if at the fourth charging station V4 for example, a battery B4 is connected and optionally both the first switching element S4e as well as the third switching element s4g according to 9 with the node K may be a short circuit at the fourth charging station V4 and in particular one to the fourth load station V4 connected battery B4 be prevented. The diode D can do this, as in 9 shown, between the first switching element S4e and the first Connection of the fourth charging station V4 be provided. Alternatively, it is also possible to use the diode D between the third switching element s4g and the second terminal of the fourth charging station V4 to arrange.

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• WO 2012/038222 A2 [0005]

Claims (15)

DC power supply device for charging a battery, in particular a battery of an electric motor vehicle, comprising: a first potential generating device (a) which can be connected on the primary side to a supply network (V) and which is configured on the secondary side for outputting a first potential (V1) to a first supply line (La); a second potential generating device (b), which on the primary side of the supply network (V) can be connected and which on the secondary side for outputting a second potential (V2) to a second supply line (Lb) is configured; a third potential generating device (c), which is connectable on the primary side to the supply network (V) and which is configured on the secondary side for outputting a third potential (V3) to a third supply line (Lc); a plurality of charging terminals (V1-V5; V1-V5; V4 ', V5`) for charging a battery (B1-B5; B1-B5; B4`, B5`) electrically connected thereto; the charging connections (V1-V5; V1-V5; V4 ', V5') having a first group (V1, V4, V5; V1, V4, V5, V4 ', V5') which are connected via a respective switching device (S1, S4, S5, S1, S4, S5, S4 ', S5') is connectable to the first supply line (La) and the second supply line (Lb) for outputting a first charging voltage (U1); the charging connections (V1-V5, V1-V5, V4 ', V5') having a second group (V2, V4, V5, V2, V4, V5, V4 ', V5') which are connected via a respective switching device (S2, S4, S5, S2, S4, S5, S4 ', S5') is connectable to the second supply line (Lb) and the third supply line (Lc) for outputting a second charging voltage (U2); and the charging connections (V1-V5, V1-V5, V4 ', V5') have a third group (V3, V4, V5, V3, V4, V4, V4 ', V5') which are connected via a respective switching device (S3, S4, S5, S3, S4, S5, S4 ', S5') is connectable to the first supply line (La) and the third supply line (Lc) for outputting a third charging voltage (U3). DC power supply device according to Claim 1 , wherein the charging terminals (V1-V5; V1-V5; V4 ', V5') have a fourth group (V4, V5; V4 ', V5'), which via a respective switching device (S4, S5, S4 ', S5` Alternatively alternatively with the first supply line (La) and the second supply line (Lb) for outputting the first charging voltage (U1) or the second supply line (Lb) and the third supply line (Lc) for outputting the second charging voltage (U2) or the first supply line (La) and the third supply line (Lc) for outputting the third charging voltage (U3) is connectable. DC power supply device according to Claim 1 or 2 , wherein between at least one charging connection (V1-V5; V1, V2, V4, V5) and the associated switching device (S1-S5; S1, S2, S4, S5) a DC-voltage converter means (W1-W5; W1, W2, W4 , W5) for converting the corresponding charging voltage (U1; U2; U3) into a DC charging voltage of the battery (B1-B5; B1, B2, B4, B5) is connected. DC power supply device according to Claim 1 or 2 , wherein between at least one charging connection (V1-V5; V1-V5; V4 ', V5') and the associated switching device (S1-S5; S1-S5, S4 ', S5`) an AC converter device for converting the corresponding charging voltage ( U1; U2; U3) is connected to a charging AC voltage of the battery (B1-B5; B1-B5, B4 ', B5`). A DC power supply according to any one of the preceding claims, wherein at least one storage capacitor (CA, CB, C1, C4a, C4b) is connected between one of the first to third supply lines (La, Lb, Lc) and another one of the first to third supply lines (La, Lb , Lc) is switched. DC power supply device according to one of the preceding claims, wherein at least one mains damper device (ND) for stabilizing and / or vibration damping and / or damping of the network is provided. A DC power supply apparatus according to any one of the preceding claims, wherein the first, second and third potentials (V1, V2, V3) are different from each other. A DC power supply according to any one of the preceding claims, wherein the charging terminals (V1-V5; V1-V5; V4 ', V5`) are two-pole or three-pole. DC power supply device according to Claim 2 in which an energy management device (EM) is provided, by means of which the fourth switching device (S4, S5, S4 ', S5') is controllable, wherein the energy management device (EM) detects the state of charge of the battery (B4, B5; B4 ', B5 `) and for controlling the switching means (S4, S5, S4 ', S5`) of the fourth group in dependence on the detected state of charge of the battery (B4, B5; B4', B5`) is configured. DC power supply device according to Claim 9 wherein the energy management device (EM) is designed such that the control of the fourth switching device (S4, S5, S4 ', S5') in dependence on the detected state of charge of the battery (B4, B5, B4 ', B5') is such that with increasing state of charge of the battery (B4, B5; B4`, B5`) of one lower to a higher charging voltage (U1, U2, U3) is switched. DC power supply device according to Claim 9 wherein the energy management device (EM) is designed such that the control of the fourth switching device (S4, S5, S4 ', S5') in dependence on the detected state of charge of the battery (B4, B5, B4 ', B5') is such that is switched from a higher to a lower charging voltage (U1, U2, U3) with increasing state of charge of the battery (B4, B5, B4`, B5`). A method of charging a battery of an electric motor vehicle, comprising the steps of: providing a DC power supply device Claim 2 ; Connecting a respective battery (B1-B5; B1-B5; B4`, B5`) to the charging terminals (V1-V5; V1-V5; V4 ', V5`) of the first to fourth groups; Switching on the associated switching devices (S1-S5, S1-S5, S4 ', S5`); simultaneous charging of the batteries (B1-B5; B1-B5; B4`, B5`) with a respective first, second or third charging voltage (U1, U2, U3). Method according to Claim 12 wherein detecting a state of charge of a battery (B4, B5, B4 ', B5') connected to a charging terminal of the fourth group (V4, V5; V4 ', V5`) and controlling the associated switching means (S4, S5 S4 ', S5') of the fourth group in response to the detected state of charge of the battery (B4, B5; B4`, B5`) takes place. Method according to Claim 13 in that the control of the associated fourth switching device (S4, S5, S4 ', S5') in dependence on the detected state of charge of the battery (B4, B5, B4 ', B5') is such that with increasing state of charge of the battery (B4, B5 B4`, B5`) is switched from a lower to a higher charging voltage (U1, U2, U3). Method according to Claim 13 in that the control of the associated fourth switching device (S4, S5, S4 ', S5') in dependence on the detected state of charge of the battery (B4, B5, B4 ', B5') is such that with increasing state of charge of the battery (B4, B5 B4`, B5`) is switched from a higher to a lower charging voltage (U1, U2, U3).

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