METHOD AND DEVICE FOR OPERATING CHARGING STATIONS

Abstract

A method for supplying a number of electric charging stations with electricity, wherein AC voltage provided by an electricity source is transformed into a prescribed AC voltage level by at least one transformer via at least one star winding and at least one delta winding and subsequently routed via AC voltage lines to the number of electric charging stations and converted directly to direct current in respective charging stations from the number of electric charging stations locally by at least two rectifiers of the charging stations.

Claims

1. A method for supplying a number of electric charging stations with electricity, wherein AC voltage provided by an electricity source is transformed into a prescribed AC voltage level by at least one transformer via at least one star winding and at least one delta winding and subsequently routed via AC voltage lines to the number of electric charging stations and converted directly to direct current in respective charging stations from the number of electric charging stations locally by at least two rectifiers of the respective charging station.

2. The method as claimed in claim 1, wherein each charging station comprises at least two 6-pulse rectifiers and at least one DC isolating DC/DC converter.

3. The method as claimed in claim 2, wherein the DC isolating DC/DC converters of a plurality of the charging stations are electrically connected so as to be switchable between parallel and series arrangement and the DC/DC converters of the plurality of the charging stations are interconnected in parallel or in series in order to alter a common output voltage or a common output current of the charging stations interconnected by the DC/DC converters.

4. The method as claimed in claim 1, wherein the supply of the number of electric charging stations with electricity involves performing load management by which a total power of the number of electric charging stations is limited to a maximum power of the at least one transformer.

5. The method as claimed in claim 1, wherein the at least one transformer comprises, in addition to the at least one star winding and the at least one delta winding, at least one further winding by which a number of phase-offset phases is increased and a power factor of respective charging stations from the number of electric charging stations is increased.

6. The method as claimed in claim 5, wherein respective secondary windings of the at least one transformer are operated in grounded or ungrounded fashion.

7. The method as claimed in claim 1, wherein a total power of the number of electric charging stations is built up gradually by a multiplicity of transformers that supply the number of electric charging stations in a parallel circuit with electricity.

8. The method as claimed in claim 1, wherein the at least two rectifiers of a respective charging station are arranged in parallel, in series or in a manner switchable between a series and a parallel arrangement.

9. A transformation device for supplying a number of charging stations with electricity, wherein the transformation device comprises at least one transformer, and the at least one transformer comprises at least one delta winding and at least one star winding for transforming AC voltage arriving on the at least one transformer into a prescribed voltage level, and the at least one transformer is configured to route said voltage level via AC voltage lines directly to rectifiers of respective charging stations.

10. A charging station arrangement having a number of charging stations and a transformation device for supplying the number of charging stations with electricity, wherein the transformation device comprises at least one transformer, and the at least one transformer comprises at least one delta winding and at least one star winding for transforming AC voltage arriving on the at least one transformer into a prescribed voltage level and the at least one transformer routes said voltage level via AC voltage lines to respective charging stations, and wherein each charging station comprises at least two rectifiers that can each be supplied directly with electricity by the at least one transformer.

11. The charging station arrangement as claimed in claim 10, wherein each charging station comprises a DC/DC converter, and wherein the DC/DC converters of at least two charging stations are electrically connected via a circuit, and wherein the circuit is embodied such that the respective DC/DC converters of the at least two charging stations are connected either in parallel or in series with a charging point for a vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 depicts a schematic representation of a possible embodiment of the presented charging station arrangement.

[0042] FIG. 2 depicts a schematic representation of an interconnection of two DC/DC converters of different charging stations.

[0043] FIG. 3 depicts a charging station arrangement based on the prior art.

[0044] FIG. 4 depicts a further charging station arrangement based on the prior art.

[0045] FIG. 5 depicts yet a further charging station arrangement based on the prior art.

[0046] FIG. 6 depicts a further charging station arrangement based on the prior art.

DETAILED DESCRIPTION OF THE INVENTION

[0047] FIG. 1 shows a transformer 1 that comprises a star winding 3 and a delta winding 5. To supply respective charging stations 7, 9 and 11 with electricity, an AC voltage arriving on the transformer is first transformed into a prescribed voltage level by the transformer 1 by means of the star winding 3 and the delta winding 5 and subsequently transmitted to the charging stations 7, 9 and 11 via a 6-phase bus 13.

[0048] The charging stations 7, 9 and 11 each comprise two rectifiers 15 and 17, of which, respectively, a rectifier 17 is in electrical contact with the star winding 3 and a rectifier 15 is in electrical contact with the delta winding 5.

[0049] Direct current converted by means of the rectifiers 15 and 17 is routed from the rectifiers 15 and 17 within a respective charging station 7, 9 and 11 to a DC/DC converter 19 that converts the direct current to a prescribed voltage level and makes said voltage level available for charging an end user, such as a motor vehicle, for example.

[0050] In charging station 7, the rectifiers 15 and 17 are connected in parallel. The effect achieved by this is that two intermediate circuit voltages differing by a factor of “2” can be represented in the charging station 7, which doubles an output current range of the DC/DC converter 19.

[0051] In charging station 9, the rectifiers 15 and 17 are connected in series. The effect achieved by this is that two intermediate circuit voltages differing by a factor of “2” can be represented in the charging station 9, which halves a conversion range of a DC/DC converter 19, so that an efficiency of a DC/DC converter 19 increases.

[0052] In charging station 11, the rectifiers 15 and 17 are interconnected such that it is possible to choose between a parallel and a series connection, so that, depending on the requirement, the output current range of the DC/DC converter 19 is doubled or the conversion range of the DC/DC converter 19 is halved and, by way of example, vehicles can be supplied with 400 volt and 800 volt battery voltages in parallel.

[0053] FIG. 2 shows a DC/DC converter 21 of a first charging station and a DC/DC converter 23 of a second charging station. The DC/DC converter 21 is electrically connected to the DC/DC converter 23 such that it is possible to choose between a parallel and a series arrangement of the DC/DC converters 21 and 23.

[0054] Series connection of the DC/DC converters 21 and 23 allows an output voltage of the connected first and second charging stations to be adjusted variably, whereas parallel connection allows an output current to be adjusted variably.

[0055] FIG. 3 depicts a circuit 30 based on the prior art. A transformer 31 uses an AC bus 33 to supply power to DC/DC converters 37 of respective charging stations. In order to optimize the voltage that is output by the transformer 31 for an optimum power factor, rectifiers 35 equipped with power factor correction or a power factor correction filter are connected between transformer 31 and respective DC/DC converter 37.

[0056] FIG. 4 depicts a circuit 40 having a central rectifier 41 and a DC bus 44. In contrast to the charging station arrangement shown in FIG. 1, use of the circuit 40 requires protective elements for transmitting electric power via the DC bus 44, such as circuit breakers and overvoltage protection devices, for example.

[0057] FIG. 5 depicts a circuit 50 that is based on an isolating transformer 51. In contrast to the circuit 50, the presented method allows DC isolation by a transformer, which is operated at high frequency and therefore compact, in a DC/DC converter, so that it is possible to dispense with the 50/60 Hz isolating transformer 51 upstream of a rectifier at a respective charging station. The respective charging stations can be embodied more compactly as a result of the presented method than would be possible on the basis of the circuit 50. In addition, use of the presented method avoids no-load losses in the isolating transformer 51.

[0058] FIG. 6 depicts a circuit 60 that comprises a transformer 61 that comprises in each case a star winding 65 and a delta winding 67 for supplying power to a charging station 63. In contrast to the circuit 60, the presented method provides for respective star and delta windings to be used for multiple charging stations, as a result of which a corresponding circuit may be embodied more compactly and more cheaply on the basis of the presented method than the circuit 60. In addition, the presented method allows a reduction in wiring complexity in comparison with the circuit 60, since a connecting line 69 between transformer and charging stations does not have to be routed in a star, but rather may be embodied as a bus, tree or ring distribution, for example.