Charging points with central rectifier and switchable DC voltage controllers

Abstract

The invention relates to a device for charging electric vehicles (8), comprising at least one mains connection (1), central power electronics (2), and a plurality of charging stations (5), each of which is connected to the central power electronics (2) via a cable (10), wherein the central power electronics (2) has one or more rectifiers (3). The invention is characterized in that at least one galvanically isolating DC / DC converter (4) is connected downstream of the rectifiers (3) in the central power electronics (2), and in that the charging stations (5) each have at least one non-galvanically isolating DC / DC converter (6).

Description

[0001] The present invention relates to a device for charging electric vehicles comprising at least one mains connection, a central power electronics unit and a plurality of charging stations, each of which is connected to the central power electronics unit via a cable, wherein the central power electronics unit has one or more rectifiers.

[0002] Such a charging device for electric vehicles is known from patent application US 2022 / 0363155 A1. The charging device is designed to simultaneously charge multiple electric vehicles with different power requirements. To satisfy these different power requirements when charging electric vehicles, a switching matrix is ​​provided that interconnects DC power components in such a way that the highest possible charging power required by the respective electric vehicle is provided at the individual charging stations. This is achieved by a computer networking the corresponding DC / DC converters with the charging stations via the switching matrix in such a way that the power drawn at the charging stations corresponds as closely as possible to the maximum permissible charging power of the connected electric vehicle. In this way, electric vehicles can be charged particularly quickly and efficiently.

[0003] The object of the present invention is to provide a device for charging several electric vehicles with several charging stations, which requires as few and inexpensive electronic components as possible and at the same time enables a high degree of flexibility when charging electric vehicles with higher charging capacities.

[0004] This object is achieved according to the invention by patent claim 1, advantageous embodiments of the present invention can be taken from the dependent patent claims, the description and the figures.

[0005] The present invention is characterized by the fact that at least one galvanically isolating DC / DC converter is connected downstream of the rectifiers in the central power electronics, and that the charging station each has at least one non-galvanically isolating DC / DC converter. For standards and safety reasons, the individual charging stations must be galvanically isolated from the power supply from the mains connection. This galvanic isolation is usually achieved at the DC voltage level by a DC / DC converter, also called a potential-isolating DC / DC converter. In addition to galvanic isolation, this DC / DC converter also has the task of converting a first DC voltage into a second, usually significantly higher DC voltage.According to the invention, the rectifiers, which provide the DC voltage required for the charging stations, are arranged in the central power electronics unit, followed by a galvanically isolating DC / DC converter, so that the charging stations connected to the output of the galvanically isolating DC / DC converter via a cable are all centrally galvanically isolated from the mains. This has the major advantage that the charging stations themselves do not need to have a galvanically isolating DC / DC converter; instead, a much cheaper and more compact, non-galvanically isolating DC / DC converter can be used in the charging station. This DC converter provides the charging voltage required for the respective electric vehicle but does not have to perform a galvanic isolation function. Central galvanic isolation thus enables a particularly cost-effective and compact design of charging stations.This can result in enormous economic benefits, particularly with a larger number of charging stations connected to a central power electronics system.

[0006] In a first embodiment of the present invention, the central power electronics comprises a plurality of rectifiers and / or a plurality of galvanically isolating DC / DC converters. When the charging stations have a high power demand, one rectifier and one galvanically isolating DC / DC converter are often not sufficient to supply the connected charging stations with sufficient charging power when fully occupied by electric vehicles due to their limited performance. In this case, it is advantageous to connect a plurality of rectifiers and / or galvanically isolating DC / DC converters in parallel so that the maximum electrical power provided by the grid connection can be utilized. It is also possible, when the power demand is particularly high, to supply the central power electronics with two or more grid connections in order to provide an even higher charging power.

[0007] Advantageously, it is also provided that at least one galvanically isolating DC / DC converter is present in one or more charging stations in addition to the non-galvanically isolating DC / DC converter. In this case, one charging station can be used to charge multiple electric vehicles by providing two or more charging points in the charging station. Since the two or more electric vehicles must be galvanically isolated from each other during the charging process, the additional DC / DC converters must be galvanically isolating to meet safety requirements and the standard.

[0008] In a further embodiment of the present invention, it is provided that in at least one charging station, the outputs of the non-galvanically isolating DC / DC converter can be connected to the outputs of the at least one galvanically isolating DC / DC converter via a switch. If only a single vehicle is connected to the charging station, the outputs of the non-galvanically isolating DC / DC converter and the at least one galvanically isolating DC / DC converter can be combined by connecting the outputs of the non-galvanically isolating DC / DC converter and the at least one galvanically isolating DC / DC converter in parallel, thus also accommodating increased charging power of electric vehicles.Since in this case only one electric vehicle is being charged and a galvanically isolating DC / DC converter is already present in the central power electronics, the non-galvanically isolating DC / DC converter and the galvanically isolating DC / DC converter can be easily interconnected in the charging station, since potential separation is always ensured in the central power electronics.

[0009] In a further embodiment of the present invention, the central power electronics comprises a switching matrix that connects the outputs of the galvanically isolated DC / DC converters in the central power electronics to the cables leading to the charging stations. Such a switching matrix can increase flexibility with regard to increased charging power requirements of the charging stations. In particular, any number of galvanically isolated DC / DC converters and thus also upstream rectifiers can be connected in parallel, thus delivering increased charging power to the respective charging stations.

[0010] In a further embodiment of the invention, the central power electronics system has at least one computer that records the maximum charging power drawn by the electric vehicles at the charging stations and compares it with the maximum permissible power of the components in the central power electronics system. This computer, which can be centrally or decentrally configured, ensures that none of the electronic components involved in the charging process are overloaded. This applies both to the electronic components in the charging station and to the electronic components of the central power electronics system. None of the components involved may be overtaxed. Therefore, the computer ensures that the charging stations are not overloaded, and that the central power electronics and, if applicable, the grid connection cannot be overloaded.For this purpose, the maximum performance of the components involved is stored in the computer and is taken into account when controlling the charging processes.

[0011] Advantageously, it is also provided that the computer controls the switching matrix in such a way that the maximum permissible charging power is always available to the electric vehicles for all components involved in the charging process. In this case, the computer can control the switching matrix within the maximum permissible load of the electronic components so that even power-hungry electric vehicles are supplied with the highest possible charging power at the charging stations. Overloading of the components involved is avoided, however, since the link in the chain with the least load always determines the maximum possible charging power for the charging process. The flexible interconnection of galvanically isolated DC / DC converters and rectifiers via the switching matrix, however, enables a flexible provision of high power for the charging stations.

[0012] The present invention is described and explained below with reference to several figures. They show: Fig. 1 shows a charging device according to the invention for charging electric vehicles with several charging stations and a central power electronics with centrally arranged galvanically isolating DC / DC converters and non-galvanically isolating DC / DC converters in the charging stations, Fig. 2 a charging device according to the invention, wherein the charging stations have galvanically isolating DC chopper units in addition to the non-galvanically isolating DC chopper units and Fig. 3 a charging device according to the invention, wherein the central galvanically isolating DC / DC converters can be connected on the output side via a switching matrix for particularly high charging power at the charging stations.

[0013] In Fig. 1 shows a charging device according to the invention, which has a central power electronics unit 2, to which a plurality of charging stations 5 are connected via cables 10. At each of these charging stations 5, an electric vehicle 8 can be charged. Such charging devices are typical for charging parks for electric vehicles, as installed in larger parking lots. The central power electronics unit 2 is connected to the three-phase network 1 and is supplied with electrical energy from it. The central power electronics unit 2 consists, on the one hand, of a plurality of rectifiers 3 connected in parallel and, connected to them, a plurality of galvanically isolating DC / DC converters 4. The rectifiers 3 are connected in parallel so that each galvanically isolating DC / DC converter 4 can draw on the maximum available power required in the charging station 5.The galvanically isolating DC / DC converters 4 have two functions: first, they galvanically isolate the charging stations 5 from the mains connection 1 and the other electronic components of the central power electronics 2, and second, they increase the DC voltage of the rectifiers 3 to a significantly higher output voltage. Electric vehicles 8 now have a charging voltage of 800 volts, so the voltage available at the charging stations 5 should be at least 800 volts. In the arrangement shown in . Fig. 1, the output voltage of the galvanically isolated DC / DC converters is 950 volts, which is then applied to the charging stations 5 via cables 10. Each of the charging stations 5, in turn, contains a non-galvanically isolated DC / DC converter 6, which provides the charging voltage required for the respective connected electric vehicle 8. This charging voltage can be regulated by the non-galvanically isolated DC / DC converters 6, for example, in the range of 150 to 1,000 volts.

[0014] Since all charging stations 5 are already galvanically isolated from the central power electronics 2 by a galvanically isolating DC / DC converter 4, it is sufficient for the charging stations 5 that a non-galvanically isolating DC / DC converter 6 is present in each charging station 5, which is significantly more compact than galvanically isolating DC / DC converters 4 and is also more cost-effective.

[0015] Furthermore, a computer 11 is provided, which monitors the power flows to the charging stations 5 and ensures that none of the involved electronic components, such as the rectifier 3, the galvanically isolating DC / DC converters 4, and the non-galvanically isolating DC / DC converters 6, are overloaded. However, within the maximum permissible loads, the computer 11 ensures that the charging stations can draw the highest possible charging power from the electric vehicles 8, thus keeping the charging process as short as possible.

[0016] The embodiment in Fig. 2 differs from the embodiment in Fig. 1 in that in each of the charging stations 5, in addition to the non-galvanically isolating DC / DC converter 6, there is now at least one further galvanically isolating DC / DC converter 4. This can also be connected to the non-galvanically isolating DC / DC converter 6 via a switch 7 if only one electric vehicle 8 is connected to the charging station 5 at a time. When the switch 7 is open, at least two electric vehicles 8 can be connected to a charging station 5. The more galvanically isolating DC / DC converters 4 there are at a charging station, the more electric vehicles 8 can be connected. However, the number of connected electric vehicles is limited by the maximum power of the central power electronics 2.The galvanically isolating DC / DC converters 4 and the non-galvanically isolating DC / DC converter 6 can never provide more charging power for an electric car 8 than can be provided by the central power electronics 2, even when the switch 7 is closed. This must be taken into account when dimensioning the electronic components in the charging stations 5 and in the central power electronics 2 in order to enable optimal, economical operation of the entire charging device.

[0017] Fig. Figure 3 shows a further embodiment of the present invention, in which the embodiment in Fig. 2 in addition to the central power electronics 2, a switching matrix 9 which can be controlled by the computer 11. In this case, the outputs of the galvanically isolating DC / DC converters 4 of the central power electronics 2 can be connected particularly flexibly, so that the individual charging stations 5 are not limited to the maximum power of a galvanically isolating DC / DC converter 4 in the central power electronics 2 when calling up the charging power, but rather all galvanically isolating DC / DC converters 4 in the central power electronics 2 that are not currently loaded are available, in order to be able to charge, for example, electric vehicles 8 with particularly high power requirements at a charging station 5. Thus, the design in Fig.3 particularly flexible charging of multiple electric vehicles 8, even when one or more electric vehicles 8 have a particularly high power requirement, since the charging power of a charging station 5 to which no electric vehicle 8 is currently connected does not have to be directed to this charging station 5 via the switching matrix 9, but can be made available to other charging stations 5. Of course, in this case too, the maximum possible charging power per charging station is limited by the electronic components of the DC / DC converters 6, 4 in the respective charging station 5. List of reference symbols 1 mains connection 2 central power electronics 3 rectifiers 4 galvanically isolating DC / DC converters 5 Charging station 6 DC chopper 7 switches 8 electric vehicles 9 Switch matrix 10 cables 11 computers QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] US 2022 / 0363155 A1

[0002]

Claims

[1] Device for charging electric vehicles (8) comprising at least one mains connection (1), a central power electronics unit (2) and several charging stations (5), each of which is connected to the central power electronics unit (2) via a cable (10), wherein the central power electronics unit (2) comprises one or more rectifiers (3), characterized by , that at least one galvanically isolating DC chopper (4) is connected downstream of the rectifiers (3) in the central power electronics (2) and that the charging stations (5) each have at least one non-galvanically isolating DC chopper (6). [2] Device for charging electric vehicles (8) according to claim 1, characterized by , that the central power electronics (2) has several rectifiers (3) and / or several galvanically isolating DC choppers (4). [3] Device for charging electric vehicles (8) according to claim 1 or claim 2, characterized by, that in one or more charging stations (5) in addition to the non-galvanically isolating DC-DC converter (6) at least one galvanically isolating DC-DC converter (4) is present. [4] Device for charging electric vehicles (8) according to one of claims 1 to 3, characterized by , that in at least one charging station (5) the outputs of the non-galvanically isolating DC-DC converter (6) and the outputs of the at least one galvanically isolating DC-DC converter (4) can be connected via a switch (7). [5] Device for charging electric vehicles (8) according to one of the preceding claims, characterized by , that the central power electronics (2) has a switching matrix (9) which connects the outputs of the galvanically isolating DC controllers (4) in the central power electronics (2) to the cables (10) to the charging stations (5). [6] Device for charging electric vehicles (8) according to one of the preceding claims, characterized by , that the central power electronics (2) has at least one computer (5) which records the maximum charging power requested by the electric vehicles (8) at the charging stations (5) and compares it with the maximum permissible power of the components in the central power electronics (2). [7] Device for charging electric vehicles (8) according to claims 5 and 6, characterized by , that the computer (5) controls the switching matrix (9) in such a way that the maximum permissible charging power is always available for all components involved in the charging process at the electric vehicles (8).

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