DE102018107824B4 - Electric charging device - Google Patents

Abstract

Electric charging device (10) with
a power converter arrangement (12) having a DC connection (14) and an n-phase AC connection (16), wherein the DC connection (14) can be electrically connected to the electrical energy storage (20) of the electrically powered vehicle (30) and the n-phase AC connection (16) can be electrically connected to the mains current (18),
characterized by the fact that
The converter arrangement (12) comprises a transformer (32), at least two rectifiers (50, 52, 54, 56, 58, 60) and a switching device (48), wherein the transformer has an n-phase primary coil (46) and at least two n-phase secondary coils (34, 36, 38, 40, 42, 44), wherein the primary coil (46) is connected to the n-phase AC terminal (16) and the at least two secondary coils (34, 36, 38, 40, 42, 44) are each connected to a rectifier (50, 52, 54, 56, 58, 60), wherein the at least two rectifiers (50, 52, 54, 56, 58, 60) can be interconnected via the switching device (48) and the switching device (48) is connected to the DC terminal (14) is connected, wherein the switching device (48) can be directly electrically connected to the electrical energy storage device (20) via the DC connection (14).

Description

The invention relates to an electric charging device for charging an electrical energy storage device of an electrically powered vehicle with a power converter arrangement having a DC connection and an n-phase AC connection, wherein the DC connection can be electrically connected to the electrical energy storage device of the electrically powered vehicle and the n-phase AC connection can be electrically connected to the mains power supply.

Such electrical charging devices are known from the prior art and typically feature a power converter arrangement, which serves in particular to convert multiphase alternating current, for example three-phase mains current, into direct current, and to convert direct current stored in the energy storage device into alternating current for feeding into the power grid. The voltage level on both the input and output sides is variably adjustable.

The US 2013/0134935 A1 For example, a DC fast charger with multiple rectifiers, each connected to a DC-DC converter, is disclosed. The rectifiers are connected to a multi-phase power source and convert multi-phase AC current into DC current. The DC-DC converters, connected in parallel, convert the high DC voltage present at the rectifier outputs into a lower charging DC voltage. In this way, the DC fast charger provides the DC current required for the rapid charging of the energy storage system of an electric vehicle.

Disadvantages of the in the US 2013/0134935 A1 The described design is that the DC fast charger is designed for a single, predefined DC charging current with a predefined DC voltage and a predefined current. Other energy storage devices that have a charging DC voltage or current that differs from the predefined DC charging voltage or current cannot be used with the charger described in the description. US 2013/0134935 A1 The described version of the charging device cannot be used for charging.

Furthermore, the DE 10 2016 102 053 A1 and the DE 10 2016 103 011 A1 A charging station for charging the electrical energy storage device of an electric vehicle, wherein the charging station has a multi-stage charging device. The multi-stage charging device comprises a transformer, at each of whose transformer outputs a rectifier is arranged. The rectifiers are electrically connected to a DC-to-voltage converter via a switching device. In operation, the charging device converts the multi-phase alternating current into a direct current required for charging the electrical energy storage device. In a preliminary stage, a DC voltage is preset via a corresponding circuit of the rectifiers using the switching device, and the DC-to-voltage converter downstream of the switching device sets the DC voltage required for charging the electrical energy storage device. A disadvantage of such multi-stage charging devices is their complex and costly design, as several stages and complex and costly DC-to-voltage converters are required to set the DC voltage required for charging the electrical energy storage device.

The object of the invention is therefore to provide a single-stage charging device which provides different voltage and current levels for charging the electrical energy storage device and forms a galvanic isolation from the power grid.

This problem is solved by a charging device having the features of the main claim.

By comprising a transformer, at least two rectifiers, and a switching device, the power converter arrangement includes an n-phase primary coil and at least two n-phase secondary coils. The primary coil is connected to the n-phase AC terminal, and the at least two secondary coils are each connected to a rectifier. The at least two rectifiers can be interconnected via the switching device, which is connected to the DC terminal and can be directly connected to the electrical energy storage device via the DC terminal. This allows the mains current to be converted into different DC currents required for charging the energy storage device. Therefore, with the charging device according to the invention, energy storage devices can be charged with different DC voltages and currents. This design of the charging device allows the use of simple and cost-effective electrical components, as relatively low electrical voltages are transmitted and converted from the secondary side of the transformer. Furthermore, this design of the charging device eliminates the need for separate galvanic isolation. Due to the defined stray inductance of the transformer, a choke coil or other inductors arranged after the transformer can be omitted to enable rectification. This reduces the cost of the charging device.

In a preferred embodiment, the at least two rectifiers can be connected in series and in parallel. Connecting the rectifiers in series allows the DC voltage provided for charging the energy storage device to be varied, with the DC voltage varying depending on how many rectifiers are connected in series. Similarly, connecting the rectifiers in parallel allows the current to be varied, with the number of rectifiers connected in parallel being the determining factor. Additionally, the rectifiers can be configured as variable or fixed, with fixed rectifiers converting the AC voltage into defined, constant DC voltages and variable rectifiers converting the AC voltage into variable DC voltages. Fixed and variable rectifiers can be combined so that the output DC voltage varies depending on how many rectifiers are connected in series and what DC voltages the variable rectifiers provide. This allows the DC current to be easily adapted to the connected energy storage device.

Preferably, the transformer has six n-phase secondary windings and six rectifiers, with each n-phase secondary winding connected to a separate rectifier. This converts the mains voltage into six relatively small AC voltages, which are then converted into six relatively small DC voltages by the rectifiers. In this way, the switching device allows for the easy adjustment of many different DC currents and voltages. Furthermore, the rectifiers can be implemented cost-effectively, as they convert relatively small AC voltages into DC voltages. In a preferred embodiment, the at least two rectifiers comprise field-effect transistors, preferably silicon-based MOSFETs interconnected in an active front-end topology. Because the MOSFETs conduct relatively small AC voltages, MOSFETs with a low voltage rating can be used, and such MOSFETs can be manufactured in very high volumes, thus making them cost-effective.

Preferably, the power converter unit is designed to be bidirectional. A bidirectional design of the power converter arrangement allows the electricity stored in the energy storage device to be fed into the power grid.

Preferably, the charging device is arranged in a charging station for charging the electrical energy storage system of the electric vehicle, thereby reducing the vehicle's weight. Alternatively, the charging device is arranged within the electric vehicle itself. This allows the electric vehicle's energy storage system to be charged at different charging stations, as the adjustment of the grid current to the electrical current required for charging the energy storage system is handled within the vehicle.

Preferably, the power converter arrangement includes capacitors.

• 1 eine schematische Darstellung eines elektrisch angetriebenen Kraftfahrzeugs, das zum Laden seines Energiespeichers mit einer Ladestation verbunden ist, und
• 2 eine schematische Darstellung einer in der Ladestation aus 1 angeordneten elektrischen Ladevorrichtung.

The invention is explained in more detail with reference to the drawings. These show:

• 1 a schematic representation of an electrically powered motor vehicle connected to a charging station for charging its energy storage, and
• 2 a schematic representation of a charging station made of 1 arranged electric charging device.

1 Figure 1 shows a schematic representation of a motor vehicle 30 with an energy storage device 20 arranged therein. The energy storage device 20 is connected to a charging station 70 via a charging cable 21, the charging station 70 being connected to a power source 19, which is located in the 1 This is exemplified as a power plant. The power source 19 supplies the charging station 70 with a grid current 18, which is a three-phase alternating current. The nominal voltage of the grid current 18 is 3-30 kV for medium voltage and 60 kV or 110 kV for high voltage. For medium voltage, a low-voltage transformer is connected upstream so that the charging device 10 is supplied with 400 V or 480 V.

The energy storage device 20 is charged via the charging station 70, whereby the mains current 18 provided by the power source 19 is converted and adapted via a charging device 10 arranged in the charging station 70 in such a way that the energy storage device 20 can be charged by it.

2 Figure 1 shows a schematic representation of the charging device 10. The charging device 10 has a three-phase AC connection 16 and a DC connection 14, with the three-phase AC connection 16 being used for... The charging device 10 is connected to the mains power 18 and, via the DC connection 14, to the energy storage device 20 of the electrically powered vehicle 30. Within the charging device 10, the three-phase AC connection 16 is connected to a three-phase primary coil 46 of a transformer 32, for example, a toroidal transformer. The transformer 32 has an iron core (not shown in the figures), with the primary coil 46 arranged on the primary side of the transformer 32. Six three-phase secondary coils 34, 36, 38, 40, 42, 44 are arranged on the secondary side of the transformer 32. The secondary coils 34, 36, 38, 40, 42, 44 have such a number of turns that the three-phase alternating current applied to the AC terminal 16 is divided into six equal three-phase alternating currents, which are applied to the outputs of the secondary coils 34, 36, 38, 40, 42, 44.

Each secondary coil 34, 36, 38, 40, 42, 44 is connected to a rectifier 50, 52, 54, 56, 58, 60, wherein the rectifiers 50, 52, 54, 56, 58, 60 are field-effect transistors, in particular MOSFETs. The rectifiers 50, 52, 54, 56, 58, 60 convert the three-phase alternating currents into six equal direct currents U _{_a} .

The rectifiers 50, 52, 54, 56, 58, 60 are interconnected via a switching device 48. The switching device 48 allows the rectifiers 50, 52, 54, 56, 58, 60 to be connected in series and in parallel, with two rectifiers 58, 60 being permanently connected in series. The switching device 48 has twelve switches S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 for connecting the other rectifiers 50, 52, 54, 56. 1 None of the switches are activated.

The functionality of the charging device 10 will be explained below using examples.

If, for example, the energy storage device 20 is to be charged with a maximum DC voltage of approximately 960 V, all rectifiers 50, 52, 54, 56, 58, 60, each with an output voltage of 160 V, are connected in series, with the input voltage of the transformer 32, supplied by the mains current 18, being 480 V. The output voltages of the transformer 32 are 60 V per secondary coil 34, 36, 38, 40, 42, 44, and 60 V, with the output voltages of the transformer 32 being increased to 160 V by a boost converter. Switches S1, S3, S6, and S9 are actuated during this process. By connecting rectifiers 50, 52, 54, 56, 58, and 60 in series, the DC voltages are added together, so that the DC voltage available for charging the energy storage device 20 is the sum of all DC voltages. For example, if a lower DC voltage is required to charge the energy storage device 20, only four of the rectifiers 54, 56, 58, and 60 are connected in series, with switches S5, S6, and S10 being actuated.

The current of the direct current available for charging the energy storage device 20 can also be changed in the same way by connecting the individual rectifiers 50, 52, 54, 56, 58, 60 in parallel. Thus, the current of the direct current available for charging the energy storage device 20 varies depending on how many rectifiers 50, 52, 54, 56, 58, 60 are connected in parallel.

In addition, the charging device 10 or the power converter arrangement 12 is designed bidirectionally, so that, for example, in the event of peak electricity demand on the power grid 18, the power grid 18 can draw on the energy storage device 20 arranged in the vehicle 30 and extract electrical energy from it.

Other constructive embodiments besides those described are also possible, which fall within the scope of protection of the main claim.

Claims (8)

An electric charging device (10) with a power converter arrangement (12) having a DC connection (14) and an n-phase AC connection (16), wherein the DC connection (14) is electrically connectable to the electrical energy storage device (20) of the electrically powered vehicle (30) and the n-phase AC connection (16) is electrically connectable to the mains power (18), characterized in that the power converter arrangement (12) has a transformer (32), at least two rectifiers (50, 52, 54, 56, 58, 60) and a switching device (48), wherein the transformer has an n-phase primary coil (46) and at least two n-phase secondary coils (34, 36, 38, 40, 42, 44), wherein the primary coil (46) is connected to the n-phase AC connection (16) and the at least two secondary coils (34, 36, 38, 40, 42, 44) are each connected to a rectifier (50, 52, 54, 56, 58, 60), wherein the at least two rectifiers (50, 52, 54, 56, 58, 60) can be interconnected via the switching device (48) and the switching device (48) is connected to the DC connection (14), wherein the switching device (48) can be directly electrically connected to the electrical energy storage device (20) via the DC connection (14). Electric charging device after Claim 1 , characterized in that the at least two rectifiers (50, 52, 54, 56, 58, 60) can be connected in series or in parallel with each other. Electric charging device after Claim 1 , characterized in that the transformer (32) has six n-phase secondary coils (34, 36, 38, 40, 42, 44) and six rectifiers (50, 52, 54, 56, 58, 60), wherein each n-phase secondary coil (34, 36, 38, 40, 42, 44) is connected to a rectifier (50, 52, 54, 56, 58, 60). Electric charging device after Claim 1 or 2 , characterized in that the power converter arrangement (12) is bidirectional. Electrical charging device according to one of the preceding claims, characterized in that the at least two rectifiers (50, 52, 54, 56, 58, 60) comprise field-effect transistors. Electric charging device according to one of the preceding claims, characterized in that the power converter arrangement (12) is arranged in a charging station for charging the electrical energy storage devices (20) of the electrically powered vehicles (30). Electric charging device according to one of the preceding claims, characterized in that the power converter arrangement (12) is arranged in an electrically powered vehicle (30). Electrical charging device according to one of the preceding claims, characterized in that the power converter arrangement (12) has capacitors.