Converter configuration for an electricity charging station and corresponding electricity charging station

[0001] This application claims priority to German Patent Application No. 10 2017 217 753.5, filed Oct. 6, 2017, the content of such application being incorporated by reference herein in its entirety.

[0002] The present invention relates to a converter configuration for an electricity charging station. The present invention also relates to a corresponding electricity charging station.

[0003] In electrical engineering, any stationary device or electrical system that serves for supplying energy to mobile, battery-operated units, machines or motor vehicles by way of simple setting or insertion without it being necessary for the energy storage—for example the traction battery of an electric automobile—to be removed compulsorily is referred to as a charging station. Charging stations for electric automobiles are also sometimes referred to as “electricity charging stations” and can comprise a plurality of charging points.

[0004] Known here in particular are direct-current fast charging/high-performance charging (HPC) systems such as the so-called combined charging system (CCS), which is widespread in Europe. In the case of direct-current charging of the generic type, direct current is fed from the charging column directly into the vehicle and, for this purpose, is provided by way of a powerful rectifier from the electricity network or by way of large buffer accumulators at solar charging stations, for example. Situated in the vehicle is a battery management system, which communicates with the charging column directly or indirectly in order to adapt the current intensity, or to terminate the process when a capacity limit is reached.

[0005] The power, electronics system is usually located in this case in the charging column. Since the direct-current connections of the charging column are connected directly to corresponding connections of the traction battery, it is thus possible for high charging currents to be transmitted with little loss, which allows short charging times.

[0006] In the various charging, stations used worldwide, a wide variety of topologies are used for the power electronics system. Known in particular are charging stations that additionally use an energy storage in the form of a battery. However, a plurality of topologies in the power electronics system are also possible for the connection of a battery.

[0007] For instance, US 2015202973 and WO 15103164, both of which are incorporated by reference herein, disclose converter constructions for a charging station for electric vehicles, which converter constructions enable additional energy storage batteries to be installed in the respective charging station. The arrangement consists in each case of a rectifier connected to the network followed by a DC voltage converter or DC chopper. The respective battery is connected on one side to the electricity network and on the other side to the charging station.

[0008] JP 2012019602, US 2015328999 and US 2012074901, all of which are incorporated by reference herein, describe further fast-charging columns for charging electric vehicles with additional energy storage batteries.

[0009] US 2015061569 and US 2008067974, both of which are incorporated by reference herein, finally discuss in each case a vehicle charging station with an additional energy storage and a network connection connected by means of a converter.

[0010] The invention provides a charging station for an electricity charging station and a corresponding electricity charging station according to the independent claims.

[0011] A preferred embodiment of the invention is based on a network connection with 55 kW via a small AC/DC rectifier. A small DC/DC converter then follows. Finally, a DC/DC controller for the battery follows in order to charge the energy from the network into the storage battery or to discharge the battery and provide a large amount of power for charging the vehicle. Furthermore, a DC/DC controller is also provided for the vehicle, which DC/DC controller concentrates the power from the network and from the battery and provides the desired charging voltage of 200 to 950 V to the vehicle.

[0012] The proposed approach is based on the knowledge that there are various ways to design a converter topology in a charging station. A contained battery can thus be integrated in a wide variety of ways. Converters can likewise be used in a very wide variety of numbers. The conceivable solutions differ here significantly in terms of their efficiency.

[0013] The invention also takes into account the fact that most known charging solutions provide charging columns, which draw the required charging energy directly from the network and therefore do not have an additional storage. An additional storage can be added very easily in these charging columns by virtue of said storage being connected on the AC side to the network and to the charging column. This is not necessarily the most efficient solution. Also, additional stores are often not accommodated in the same housing as the charging column or the power electronics system, which requires more outlay in terms of installation. The charging columns furthermore often have a specific minimum size because topologies with outdated IGBT technologies are used. These are cheap but require more installation space.

[0014] In contrast, one preference of the invention disclosed here lies in the introduced possibility of installing the energy storage—in this case a battery—in the same housing as the power electronics system in order to minimize the installation outlay. The overall solution is also very compact in order not to obstruct the visibility in road traffic significantly. This requires the use of very fast converter topologies at high switching frequencies, which in turn requires the use of SiC MOS modules. In this case, the battery is accommodated in the DC part, which improves the efficiency of the charging station and significantly reduces the production costs thereof.

[0015] Further advantageous configurations of the invention are specified in the dependent patent claims.

[0018] The FIGURE illustrates by way of example an electricity charging station equipped with a charging station (10) according to aspects of the invention. A rectifier (AC/DC converter 11) serves here for connection to the public TN or TT low-voltage network. A first DC voltage converter (DC/DC converter 12) connected to said rectifier (11) transmits the voltage for protection against ground faults to the internal IT network of the charging station (10).

[0019] At this location, essentially two power paths split up inside the charging station (10): a first DC chopper (13) feeds the connected battery (21, 22) comprising strings (21, 22), of which there are two in accordance with the image, and allows the energy stored in such a way to be fed back for the accelerated charging of connected vehicles. Each string may include multiple modules and each module may include multiple cells. For the supply of power to said connected vehicles, a second DC chopper (14) is provided with, for example, a DC EMC filter (15) connected downstream and, for example, a second DC voltage converter (16), preferably operated in discontinuous conduction mode (DCM), which second DC chopper and second DC voltage converter have suitably protected connection lines for the purpose of power transmission. The associated pilot line (18) can be provided with an overvoltage protection system (19) depending on the charging standard and the charging voltage.