DC converter having a wide output voltage range

Abstract

The invention relates to a DC converter (1) having a wide output voltage range and to a charging device (20) for electric vehicles (30) which has a DC converter (1) of this type. The DC converter (1) according to the invention is equipped with a high-frequency alternating voltage generator (14) for connection to a supply grid (3), the high-frequency alternating voltage generator being designed to generate a plurality of high-frequency alternating voltage signals according to a first control signal (8), and with a transformer assembly (2) which is connected, on the input side thereof, to the high-frequency alternating voltage generator (14) and which has a plurality of secondary windings (5). The DC converter (1) also has a plurality of at least three rectifiers (6, 6-1, 6-2, 6-3, 6-4), each of the rectifiers (6, 6-1, 6-2, 6-3, 6-4) being connected, on the input side thereof, to a relevant secondary winding (5) of the transformer assembly (2) and being designed to rectify an alternating voltage received from the transformer assembly (2) into a direct voltage, and a switching matrix (10) which is connected to respective outputs of the plurality of rectifiers (6, 6-1, 6-2, 6-3, 6-4) and which is designed to interconnect, according to a second control signal (9), the respective direct voltages generated by the rectifiers (6, 6-1, 6-2, 6-3, 6-4) by connecting the outputs of the rectifiers (6, 6-1, 6-2, 6-3, 6-4) in parallel and / or in series and to output said direct voltages at a rectifier output (11) of the DC converter (1) in the form of a total direct voltage. The charging device (20) according to the invention for at least one electric vehicle (30) is equipped with at least one DC converter (1) according to the invention.

Description

[0001] 202416797

[0002] 1

[0003] Description

[0004] DC controller with wide output voltage range

[0005] Technical field

[0006] The invention relates to a DC controller with a wide output voltage range and a charging device for electric vehicles with such a DC controller.

[0007] Technical background

[0008] Traction batteries for battery-powered vehicles (electric vehicles) vary considerably depending on the application, particularly regarding required parameters such as DC voltage, DC current, and battery capacity. For example, battery voltages in electric vehicles can range from 200 to 1300 volts with battery capacities of 5 to 500 kilowatt-hours. Depending on the model, traction batteries can be charged with charging powers ranging from tens and hundreds of kilowatts up to the megawatt range. This wide range of parameters places high demands on the system architecture used, particularly concerning cost-efficiency and the flexibility of the required charging infrastructure.

[0009] The electrical energy, according to the aforementioned battery-specific parameters, is typically supplied by means of galvanically isolated DC converters, also known as AC / DC converters, or in two stages after rectification by galvanically isolated DC / DC converters in DC fast charging stations. Such fast charging stations are preferably modular and therefore scalable. The individual AC / DC or DC / DC converters, built as modules, can be connected in parallel or in series and can be operated unidirectionally or, with appropriate hardware design, bidirectionally.

[0010] Furthermore, when selecting the system architecture for the DC charging infrastructure, other parameters, often interrelated, must be optimized in relation to the application objective. Examples include cost, efficiency, scalability, weight, volume, electromagnetic compatibility, noise level, cooling technology, protection class, and country- or region-specific regulatory requirements. 202416797

[0011] 2

[0012] Various circuit topologies are known, each with its own advantages and disadvantages. For example, galvanically isolated resonant architectures represent a group in which an LC resonant circuit, or in multiphase systems, a separate resonant circuit for each phase, is excited to oscillate at a higher frequency by energy pulses. If the resonant circuits, or at least a portion of their inductance, are designed as transformers, they cause a corresponding energy flow from the primary to the secondary side of the transformer. Rectification of the high-frequency secondary-side transformer voltage provides the desired DC output parameters (voltage / current / power).

[0013] It is difficult to adjust the transferred energy across a wide range of output parameters on the primary side. Consequently, after rectification on the secondary side, the voltage and power range achievable with sufficient efficiency is limited. For example, the pulses used to excite the LC resonant circuits on the primary side can be varied in terms of pulse length and amplitude to achieve the desired voltage and power data. Controlling the pulse length and phase relative to the oscillation of the resonant circuit excited by the pulses places very high demands on the semiconductor circuit, especially at low power levels. Therefore, the control must be highly precise to ensure stable adjustment of the desired voltage and power range.

[0014] Against this background, the invention aims to introduce an improved DC converter with a wide output voltage range and a charging device for electric vehicles incorporating such an improved DC converter. The invention achieves this objective through a DC converter according to claim 1 and a charging device according to claim 12. Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0015] Summary of the invention

[0016] A first aspect of the invention comprises a DC converter with a high-frequency AC voltage generator for connection to a supply network, which is configured to generate a plurality of high-frequency AC voltage signals depending on a first control signal, a transformer arrangement connected to the high-frequency AC voltage generator on the input side and having a plurality of secondary windings, and a plurality of at least three rectifiers, wherein each of the rectifiers is connected on the input side to a respective secondary winding of the transformer arrangement and is configured to generate a 202416797

[0017] The DC converter according to the invention converts the alternating voltage received from the transformer arrangement into a direct voltage. It is connected to a switching matrix linked to the respective outputs of the plurality of rectifiers. This matrix is ​​configured to combine the respective direct voltages generated by the rectifiers, depending on a second control signal, by connecting the rectifier outputs in parallel and / or series, and to output the resulting total direct voltage at a rectifier output of the DC converter. The DC converter according to the invention offers a particularly large output voltage range because the at least three rectifiers allow for numerous combinations of series and / or parallel connections of the individual rectifiers, which accordingly provide different output voltages and output currents.

[0018] In this context, a "high-frequency alternating voltage signal" refers specifically to an alternating voltage – preferably sinusoidal – with a frequency between 10 and 50 kilohertz. Within this frequency range, the transformer arrangement can be implemented in a small form factor with minimal material usage.

[0019] The high-frequency AC generator produces high-frequency AC signals depending on a first control signal. In particular, the high-frequency AC generator can adjust the amplitude of the high-frequency AC signals, as well as their frequency, depending on the first control signal.

[0020] The high-frequency AC generator can obtain the electrical power required for the high-frequency AC signals, for example, from an AC or DC power supply network. When supplied from an AC network, particularly a 50 or 60 Hz network, the generation of the high-frequency AC signals preferably occurs without rectification of the supply voltage(s), for example, by pulsed excitation of resonant circuits directly from the phase of the power supply network that has a suitable amplitude at the time the pulse is generated.

[0021] The transformer arrangement can generally consist of separate transformers for each AC signal and each rectifier, i.e., each with a primary winding for connection to an AC signal from the high-frequency AC generator and a secondary winding for connection to the subsequent rectifier, or it can be designed as a multi-phase transformer. A multi-phase transformer is particularly suitable in the case of a high-frequency AC generator for generating three high-frequency signals.

[0022] 4

[0023] AC voltage signals and exactly three rectifiers in the DC controller, since such transformer arrangements are widely available and inexpensive.

[0024] Preferably, the high-frequency AC voltage generator is configured to generate each high-frequency AC voltage signal with a phase angle different from the remaining high-frequency AC voltage signals. This has the advantage of reduced ripple in the total DC voltage generated by the DC controller and thus lower requirements for filtering the total DC voltage and / or reduced electromagnetic radiation.

[0025] Preferably, the high-frequency AC generator is designed for a three-phase power supply network. Such a power supply network is available almost everywhere. Preferably, the high-frequency AC generator draws the electrical power required for the high-frequency AC signals equally from the three phases, thereby achieving a symmetrical load on the three phases of the power supply network.

[0026] The transformer arrangement is particularly preferably configured to output an alternating voltage at least at one selected secondary winding of the transformer arrangement with an amplitude that differs from that of the remaining secondary windings of the transformer arrangement. This can be achieved, for example, by a different turns ratio of the transformer arrangement. In particular, the at least one selected secondary winding of the transformer arrangement can have a different number of turns than the remaining secondary windings of the transformer arrangement.

[0027] Accordingly, a selected rectifier of the plurality of rectifiers can be configured to output a DC voltage with a maximum amplitude that is at least approximately equal to the sum of the respective maximum amplitudes of the remaining rectifiers. This can be most easily achieved by using a different turns ratio of the transformer arrangement. With three rectifiers, the maximum amplitude of one rectifier can be equal to the sum of the maximum amplitudes of the two remaining rectifiers. Here, the maximum amplitudes of the two remaining rectifiers can be equal, which allows these two rectifiers to be connected in parallel up to the maximum amplitude. In other words, a first of the three rectifiers can be configured to output a first maximum DC voltage.

[0028] 5, and a second and a third of the three rectifiers are configured to output a second maximum DC voltage, wherein the first maximum DC voltage is at least approximately twice as large as the second maximum DC voltage.

[0029] The underlying principle can be generalized to a larger number of rectifiers than three. A fourth rectifier then has a maximum amplitude equal to the sum of the maximum amplitudes of the other three rectifiers, specifically a maximum amplitude equal to twice the next largest maximum amplitude. This can be done similarly for five or more rectifiers according to a binary series, although the complexity can increase significantly with the number of rectifiers.

[0030] The transformer assembly can have exactly three secondary windings and the DC converter exactly three rectifiers, with each rectifier being connected on its input side to one of the three secondary windings. Such a transformer assembly is particularly suitable for a single-piece transformer assembly with a common yoke, where the primary and secondary windings can optionally be connected in a star or delta configuration.

[0031] In a DC converter according to the invention with three rectifiers and three secondary windings, a control unit can be provided which is configured to generate the first and second control signals and thereby, in a first operating state for a low total DC voltage, connect two of the rectifiers in parallel and deactivate the third rectifier, in a second operating state for a medium total DC voltage, connect the two rectifiers in series and connect the rectifiers connected in series in parallel to the third rectifier, and in a third operating state for a high total DC voltage, connect the two rectifiers and the third rectifier in series.Such embodiments of the invention enable a wide output voltage range with a relatively low circuit effort and thus represent a particularly favorable compromise between effort and achievable flexibility with regard to output voltage and output power of the DC controller.

[0032] In a DC converter according to the invention with N rectifiers (N is an integer greater than 2), the switching matrix can comprise N-1 first switches, N-1 second switches, and N-1 third switches. The N rectifiers comprise a top rectifier, a bottom rectifier, and a third rectifier. 202416797

[0033] 6. At least one middle rectifier. Each of the first switches is connected between a negative output terminal of the lowest rectifier and a negative output terminal of a respective rectifier from the set of at least one middle rectifier and the highest rectifier. Furthermore, every second switch is connected between a positive output terminal of the highest rectifier and a positive output terminal of a respective rectifier from the set of at least one middle rectifier and the lowest rectifier. Finally, every third switch is connected between a positive output terminal of a respective rectifier and a negative output terminal of a respective other rectifier, with no third switch being connected between the highest rectifier and the lowest rectifier.In other words, the first switches allow the negative output terminals of the rectifiers to be connected or disconnected, the second switches allow the positive output terminals to be connected or disconnected, and the third switches allow any two adjacent rectifiers to be connected in series. This switching matrix thus enables a wide variety of parallel and series connection configurations of the rectifiers with a relatively small total number of switches, thereby allowing for a broad output voltage range for different output power levels. The terms "top," "middle," and "bottom" rectifier are derived from their electrical potentials when all rectifiers are connected in series and do not refer to their physical position within the DC converter.

[0034] Preferably, the rectifiers are designed as active rectifiers. Active rectifiers have a high efficiency because they avoid the losses caused by the threshold voltage of the rectifier diodes in passive rectifiers; however, this requires more complex control of the semiconductor switches used instead of the diodes. Conversely, active rectifiers can also be designed for bidirectional operation, i.e., they can function as inverters with reversed energy flow.

[0035] The DC controller according to the invention can be equipped with a buffer capacitor connected between the poles of the DC voltage output of the DC controller. The buffer capacitor contributes to smoothing the output voltage at the DC voltage output and can buffer sudden load changes.

[0036] A second aspect of the invention relates to a charging device for at least one electric vehicle with at least one DC converter according to the first aspect of the invention. 202416797

[0037] 7

[0038] Such a charging device can be equipped with three DC converters according to the invention for connection to a three-phase supply network, wherein a first supply network connection of a first DC converter of the three DC converters is connected to a first phase of the supply network, a second supply network connection of the first DC converter is connected to a second phase of the supply network, and a third supply network connection of the first DC converter is connected to a third phase of the supply network, wherein a second supply network connection of a second DC converter of the three DC converters is connected to the first phase of the supply network.A first supply line connection of the second DC converter is connected to the second phase of the supply network, and a third supply line connection of the second DC converter is connected to the third phase of the supply network. Furthermore, a first supply line connection of a third DC converter is connected to the first phase of the supply network, a second supply line connection of the third DC converter is connected to the third phase of the supply network, and a third supply line connection of the third DC converter is connected to a second phase of the supply network. The respective supply line connections of the respective DC converters are thus connected to the individual phases of the supply network in a rotated or permuted manner relative to each other. This allows for a more even, or at least a more even, load distribution across the phases of the supply network, particularly in one specific case.in which the outputs of the three DC converters are connected, or can be connected, to provide higher charging power. Such an architecture is suitable, for example, for a so-called power block, in which power electronics modules combined in a central unit can be flexibly interconnected and distributed to several charging ports (so-called dispensers) or routed to one of the several charging ports.

[0039] Brief description of the images

[0040] The invention is explained in more detail below with reference to illustrations of exemplary embodiments. The same reference numerals are used in the various illustrations for identical or similar functional units, so that what is said about one exemplary embodiment can be applied to the other exemplary embodiments unless otherwise stated. The illustrations show:

[0041] Fig. 1 shows a first embodiment of a DC controller according to the invention;

[0042] Fig. 2 shows a second embodiment of the DC controller according to the invention; 202416797

[0043] 8

[0044] Fig. 3 shows a table of switching states of a switching matrix of the second embodiment of the DC controller according to the invention from Fig. 2;

[0045] Fig. 4 shows a third embodiment of the DC controller according to the invention;

[0046] Fig. 5 shows a table of switching states of the switching matrix of the third embodiment of the DC controller according to the invention from Fig. 4;

[0047] Fig. 6 shows a first embodiment of a charging device according to the invention;

[0048] Fig. 7 shows a second embodiment of a charging device according to the invention, and

[0049] Fig. 8 shows an embodiment of a high-frequency alternating voltage generator for use in the DC controller according to the invention.

[0050] Detailed image description

[0051] Fig. 1 shows a first embodiment of a DC controller 1 according to the invention. The DC controller 1 has a high-frequency AC voltage generator 14 at its input, which in the example shown is supplied with electrical energy by a three-phase supply network 3. Instead of a three-phase supply network 3, other types of electrical supply could also be used, for example a single-phase supply network or a DC supply network, optionally incorporating photovoltaics, battery storage systems, and the like.

[0052] The high-frequency AC generator 14 serves to convert the electrical power drawn from the supply network 3 into several (at least three) high-frequency AC signals. "High frequency" here refers in particular to frequencies between 10 and 50 kilohertz. The high-frequency AC signals generated by the high-frequency AC generator 14 preferably have distinct phase angles, uniformly distributed over the unit circle. The amplitude and, if applicable, also the frequency of the high-frequency AC signals is determined by a first control signal 8 from a control unit 7.

[0053] 9

[0054] A high-frequency alternating voltage signal is output to a transformer arrangement 2, more precisely to a corresponding primary winding 4 of the transformer arrangement 2. The transformer arrangement 2 also has a plurality of secondary windings 5. The transformer arrangement 2 can, for example, consist of several separate transformers, each with a primary and a secondary winding 4, 5, or it can be constructed as a multi-phase transformer.

[0055] The transformer arrangement 2 has at least three secondary windings 5, which are connected via corresponding terminals to a corresponding number of rectifiers 6. Preferably, the transformer arrangement 2 has a different turns ratio for at least one such terminal. For example, with three secondary windings 5, the transformer arrangement 2 can be configured to output an AC voltage twice as high at one secondary winding as at the other two secondary windings 5.

[0056] The rectifiers 6 are designed to convert the alternating voltage received from the transformer arrangement 2 into a direct voltage. The magnitude of the direct voltage depends primarily on the amplitude of the high-frequency alternating voltage signals generated by the high-frequency AC voltage generator 14, as well as the respective turns ratio of the transformer arrangement 2 for each path to the respective rectifier 6. However, it is also conceivable to equip the rectifiers 6 with boost or buck stages, so that the direct voltage they output can also be determined by these stages, controlled by a further control signal from the control unit 7 (not shown). Fundamentally, however, each rectifier 6 is designed to output a direct voltage of a level or amplitude within an interval between a minimum and a maximum amplitude, regardless of the internal structure of the rectifier itself.

[0057] The rectifiers 6 are connected at their outputs to a switching matrix 10, which is designed to connect the rectifier outputs by series and parallel connection in such a way that a total DC voltage is output at a rectifier output 11. The magnitude of this total DC voltage is determined by the DC voltages generated by the rectifiers 6 and their summation by series connection. Furthermore, the available current, and thus the available output power of the DC controller 1, can be set by parallel connection in the switching matrix 10 as the sum of the currents of several rectifiers 6. The switching matrix 202416797

[0058] 10

[0059] 10 has three or more switching states in which different rectifiers 6 are connected in different configurations, which advantageously results in a wide output voltage and output power range of the DC controller 1.

[0060] Fig. 2 shows a second embodiment of the DC converter 1 according to the invention, which corresponds in its basic structure to the first embodiment shown in Fig. 1, so that only the differently constructed components are described below. The transformer arrangement 2 of the DC converter 1 of the second embodiment has three primary windings 4 and three secondary windings 5, each connected in a delta configuration. However, one or both sides of the transformer arrangement 2 can also be connected in a star configuration. Three rectifiers 6 are provided, corresponding to the number of secondary windings 5, and are designated 6-1, 6-2, and 6-3 to distinguish the individual units. The outputs of each rectifier 6 consist of a negative output terminal 13-n and a positive output terminal 13-p and are connected to the switching matrix 10, which is shown in greater detail in Fig. 2 than in Fig. 1.

[0061] In the second embodiment of the DC converter 1, a buffer capacitor 12 is connected between the terminals of the rectifier output 11. In the example shown, this is implemented as a single capacitor, but it can generally also be implemented as a parallel and / or series connection of several capacitors. The buffer capacitor 12 serves to smooth and buffer the output voltage of the DC converter 1.

[0062] The switching matrix 10 of the second embodiment of the DC controller 1 has two first switches S1-1, S1-2, two second switches S2-1, S2-2, and two third switches S3-1, S3-2. The number of switches in each group is one less than the number of rectifiers 6-1, 6-2, 6-3, in this case, two. The first switches S1-1, S1-2 are connected between the negative output terminal 13-n of the lowest rectifier 6-3 and a respective negative output terminal 13-n of one of the remaining rectifiers 6-1 and 6-2. The second switches S2-1, S2-2 are connected between the positive output terminal 13-p of the highest rectifier 6-1 and a respective positive output terminal 13-p of one of the remaining rectifiers 6-2 and 6-3.The third switches S3-1 and S3-2 are connected between the positive and negative output terminals of two adjacent rectifiers; more precisely, the third switch S3-1 is connected between the negative output terminal 13-n of rectifier 6-1 and the positive output terminal 13-p of rectifier 6-2, and the third switch S3-2 is connected between the negative output terminal 13-n of rectifier 6-2 and the positive output terminal 13-p of rectifier 6-3. 202416797.

[0063] 11

[0064] The first switches S1-1 and S1-2 are used to connect the negative output terminals 13-n for a parallel connection of rectifiers, while the second switches S2-1 and S2-2 are used to connect the positive output terminals 13-p. The third switches S3-1 and S3-2 are used to connect the adjacent rectifiers for a series connection.

[0065] The first switches S1-1, S1-2, the second switches S2-1, S2-2, and the third switches S3-1, S3-2 are controlled by second control signals 9 provided by the control unit 7. The control unit 7 can generally be configured as a central unit or as a distributed arrangement of several subunits.

[0066] Fig. 3 shows a table of switching states of a switching matrix 10 of the second embodiment of the DC controller 1 according to the invention from Fig. 2. The rectifier 6-1 is configured to generate a maximum output voltage Vi, the rectifier 6-2 a maximum output voltage V2, and the rectifier 6-3 a maximum output voltage V3. In the example shown, Vi and V2 are preferably equal, and V3 is twice as large as Vi or V2, respectively. The switching matrix 10 of the DC controller 1 of the second embodiment can be controlled according to the logic levels shown in the table of Fig. 3. A 0 means that the corresponding switch is open, i.e., not conducting. A 1 means that the switch is closed, i.e., conducting.

[0067] For maximum output voltage, all three rectifiers 6-1, 6-2, and 6-3 can be connected in series. To do this, the first and second switches S1-1, S1-2, S2-1, and S2-2 are opened, while the third switches S3-1 and S3-2 are closed. Due to the series connection of rectifiers 6-1, 6-2, and 6-3, the output current of the DC controller 1 is limited to the maximum current that the weakest rectifier 6-1, 6-2, and 6-3 can deliver. However, this is not a disadvantage when using the DC controller 1 to charge a battery, especially a traction battery of an electric vehicle, since high voltages typically occur towards the end of a charging cycle when the potential charging power is low due to the battery's electrochemical properties.If the maximum output voltages Vi and V2 are set to 350 volts and V3 accordingly to 700 volts, this results in an achievable maximum output voltage of 1400 volts for the DC controller 1 according to the invention.

[0068] In a second operating mode, rectifiers 6-1 and 6-2 can be connected in series. The series connection of rectifiers 6-1 and 6-2 can in turn be combined with the remaining 202416797

[0069] 12

[0070] Rectifiers 6-3 can be connected in parallel to achieve a higher output current in a medium voltage range of, in this example, a maximum of 700 volts. For lower charging powers, it is also possible to activate only either rectifiers 6-1, 6-2, or rectifier 6-3. For the second operating mode with all three rectifiers 6-1, 6-2, and 6-3, switches S1-1, S2-2, and S3-1 are closed, while switches S1-2, S2-1, and S3-2 are opened.

[0071] A third operating mode of the DC controller 1 is intended for relatively low output voltages, a maximum of 350 volts in this example. In this third operating mode, rectifier 6-3 is deactivated, while rectifiers 6-1 and 6-2 are connected in parallel. For particularly low output power, only one of rectifiers 6-1 or 6-2 could be used. For this third operating mode, the first two switches, S1-1 and S1-2, as well as the second switch, S2-1, are closed, while switches S2-2, S3-1, and S3-2 are opened.

[0072] The switching matrix 10 of the embodiment shown in detail in Fig. 2 allows for a wide output voltage range with a small number of switches. Depending on the output voltages and currents required for a specific application, the rectifiers can be connected in different configurations. The second and third operating modes can each be operated in several variations: in the second operating mode, rectifiers 6-1 and 6-2 can be connected in series, rectifier 6-3 can be operated alone, or rectifiers 6-1 and 6-2 can be connected in parallel with rectifier 6-3 (the switching states required for these variations can be easily derived). Of the three variations, the one with the highest efficiency for the required output parameters should be selected.The third operating mode can also be divided into three variants: operation of either rectifier 6-1 or rectifier 6-2 alone, or parallel operation of both rectifiers 6-1 and 6-2. Again, the variant with the most favorable efficiency for the respective application should be selected. The switching states required for the two variants of the third operating mode not shown in Fig. 3 can be easily derived.

[0073] Fig. 4 shows a third embodiment of the DC converter 1 according to the invention. In this third embodiment, the transformer arrangement 2 has four secondary windings 5 ​​and, accordingly, four rectifiers 6-1, 6-2, 6-3, and 6-4. The higher number of rectifiers 202416797

[0074] As shown in Figure 13, the switching matrix 10 also has three more first, second, and third switches each. Otherwise, the DC controller 1 of Figure 4 is functionally very similar to that of Figure 2. The maximum output voltage V4 of the fourth rectifier 6-4 is preferably twice that of the third rectifier 6-3 (V3), which in turn is twice that of the maximum output voltages V1 and V2 of the rectifiers 6-1 and 6-2. For example, V1 and V2 can be 175 volts, V3 350 volts, and V4 700 volts.

[0075] Fig. 5 shows a table of switching states of the switching matrix 10 of the third embodiment of the DC converter 1 according to the invention from Fig. 4. For the highest possible output voltage, all four rectifiers 6-1, 6-2, 6-3, and 6-4 can be connected in series. In this example, this again results in a maximum output voltage of 1400 volts. For an output voltage in the upper middle range, the rectifiers 6-1, 6-2, and 6-3 can be connected in series, and rectifier 6-4 can additionally be connected in parallel to the rectifiers connected in series. In this example, a maximum output voltage of 700 volts is achieved. For a lower middle output voltage range, the rectifiers 6-1 and 6-2 can be connected in series, and rectifier 6-3 can be connected in parallel to them, resulting in a maximum output voltage of 350 volts in this example.Finally, rectifiers 6-1 and 6-2 can be connected in parallel, resulting in a low maximum output voltage of 175 volts. The corresponding switching states of the first, second, and third switches of the switching matrix 10 are listed in the table in Fig. 5. For all operating modes except the series connection of all rectifiers 6-1, 6-2, 6-3, and 6-4, three variants with and without parallel connection can again be easily identified. Again, the variant with the best efficiency should be selected for the specific application and the desired partial load operation, which will depend significantly on the required output current.

[0076] Fig. 6 shows a first embodiment of a charging device 20 according to the invention, which is equipped with a DC controller 1 according to the invention to provide the charging parameters required for charging an electric vehicle 30, such as charging voltage and charging current. These charging parameters are determined by the design of the traction battery of the electric vehicle 30 and its current state of charge (SoC) and can vary widely from vehicle model to vehicle model. The DC controller 1 is connected to the electric vehicle 30 via a charging cable 22 and a charging plug. The charging device 1 of the illustrated embodiment also has a user interface 21, via which authentication, control, and payment of a charging process can be carried out. 202416797

[0077] 14

[0078] Fig. 7 shows a second embodiment of a charging device 20 according to the invention, which has a central unit 27, often called a power block, and a plurality of so-called dispensers 24 connected to the power block 27. The actual power electronics are centrally arranged in the power block 27 and can be flexibly distributed to the charging outputs on the dispensers 24. For this purpose, a power router 25 is provided, which can be constructed similarly to the switching matrix 10 of the DC controller 1. Examples of such power routers are known in the prior art, for example from DE 102020213788 A1. In the example shown, the power block 27 is equipped with three DC controllers 1 according to the invention, each of which is designed for connection to a three-phase supply network 3.The connections of the three DC converters 1 are each permutably connected to the respective phases, which is intended to result in the most even possible load distribution across the three phases of the supply network 3. However, a different number of DC converters 1 can also be provided, in particular a higher number than three.

[0079] The power router 25 is connected to the dispensers 24 via underground cable 26. The dispensers 24 themselves resemble conventional charging devices externally, but—apart from functional units necessary for operational safety such as surge protection, overcurrent fuses, and the like—do not contain any power electronic functional units, as these are centrally located in the power block 27. Each dispenser 24 is equipped with at least one user interface 21, one charging cable 22, and one charging plug 23.

[0080] The design of the charging device 20, with a central unit 27 and several dispensers 24, offers the advantage of increasing the utilization rate of the DC converters 1, since it is not necessary to provide a DC converter 1 with the maximum charging power available at each charging port of the charging device 20. In practice, it will only rarely occur that the total charging power demanded at the charging ports exceeds the maximum capacity of the DC converters 1 assembled in the central unit 27. In such a case, the charging power at individual or all charging ports of the charging device 20 is reduced. Various methods can be used for this reduction, such as a calculated reduction or by taking into account the respective contract and tariff classes of the individuals or companies charging their electric vehicles via the charging device 20.

[0081] In certain applications, it may be advantageous if the dispensers 24, in addition to the power electronic units of the power block, i.e. the DC controllers 1, also have local power electronic units, for example for AC charging or 202416797

[0082] 15. DC charging with low charging power and low charging voltages is designed. Reference is made to the state of the art in this regard.

[0083] Fig. 8 shows an embodiment of a high-frequency AC voltage generator 14 for use in the DC controller according to the invention. The high-frequency AC voltage generator 14 of the example in Fig. 8 is equipped on its input side with a pulse generator 15, which in the example shown is designed for an AC voltage supply from a three-phase supply network. The high-frequency AC voltage generator 14 of Fig. 8 is configured to generate high-frequency pulses with a frequency and / or duration specified by the first control signal from the phases of the supply network applied to its input. The high-frequency AC voltage generator 14 generates a plurality of high-frequency pulse trains, which are intended to correspond to the number of high-frequency AC voltage signals of the high-frequency AC voltage generator 14.The high-frequency pulse trains are output to resonant circuits 16, which are excited to oscillate by the pulse trains and typically consist of a suitable combination of an inductor and a capacitor. It is possible to make the resonant circuit 16 tunable, for example, by selectively connecting capacitors in parallel. The electrical oscillations generated by the resonant circuits 16 are output by the high-frequency AC voltage generator 14 as high-frequency AC voltage signals.

[0084] The invention has been explained in more detail with reference to illustrations of exemplary embodiments. These exemplary embodiments are intended solely to aid understanding and do not limit the invention, which is defined exclusively by the following claims.

[0085] 202416797

[0086] Reference symbol list

[0087] 1 DC controller

[0088] 2 transformer arrangement

[0089] 3 Supply network

[0090] 4 Primary winding

[0091] 5 Secondary winding

[0092] 6, 6-1, 6-2, 6-3, 6-4 rectifiers

[0093] 7 Control unit

[0094] 8 first control signal

[0095] 9 second control signal

[0096] 10 switching matrix

[0097] 11 Rectifier output

[0098] 12 Buffer capacity

[0099] 13-n negative output pole

[0100] 13-p positive output pole

[0101] 14 High-frequency AC voltage generator

[0102] 15 Pulse generator

[0103] 16 Resonance circuit

[0104] 51-1, S1-2, S1-3 first switch

[0105] 52-1, S2-2, S2-3 second switch

[0106] 53-1, S3-2, S3-3 third switch

[0107] 20 Charging device

[0108] 21 User interface

[0109] 22 charging cables

[0110] 23 charging plugs

[0111] 24 dispensers

[0112] 25 Power Routers

[0113] 26 underground cables

[0114] 27 Power- Block

[0115] 30 electric vehicles

Claims

202416797 17 Patent claims 1. A DC converter (1) with a high-frequency AC voltage generator (14) for connection to a supply network (3), which is configured to generate a plurality of high-frequency AC voltage signals depending on a first control signal (8), a transformer arrangement (2) connected to the high-frequency AC voltage generator (14) on the input side, wherein the transformer arrangement (2) has a plurality of secondary windings (5), a plurality of at least three rectifiers (6, 6-1, 6-2, 6-3, 6-4), wherein each of the rectifiers (6, 6-1, 6-2, 6-3, 6-4) is connected on the input side to a respective secondary winding (5) of the transformer arrangement (2) and is configured to convert an AC voltage received by the transformer arrangement (2) into a DC voltage, and a connection with respective outputs of the plurality of rectifiers (6, 6-1, 6-2, 6-3, 6-4) connected switching matrix (10) which is designed toDepending on a second control signal (9), the respective DC voltages generated by the rectifiers (6, 6-1, 6-2, 6-3, 6-4) are combined by connecting the outputs of the rectifiers (6, 6-1, 6-2, 6-3, 6-4) in parallel and / or in series and output as a total DC voltage at a rectifier output (11) of the DC controller (1).

2. The DC controller (1) of the preceding claim, wherein the high-frequency AC voltage generator (14) is configured to generate each high-frequency AC voltage signal with a phase angle different from the remaining high-frequency AC voltage signals.

3. The DC controller (1) of one of the preceding claims, wherein the high-frequency alternating voltage generator (14) is configured for a three-phase supply network (3).

4. The DC controller (1) of one of the preceding claims, wherein the transformer arrangement (2) is configured to output an alternating voltage of an amplitude different from that of the remaining secondary windings (5) of the transformer arrangement (2) at least on a selected secondary winding (5) of the transformer arrangement (2).

5. The DC converter (1) of one of the preceding claims, wherein a selected rectifier (6-3, 6-4) of the plurality of rectifiers (6, 6-1 , 6-2, 6-3, 6-4) is configured to output a DC voltage with a maximum amplitude that is at least approximately equal to a sum of the respective maximum amplitudes of the remaining rectifiers (6, 6-1 , 6-2, 6-3) of the plurality of rectifiers (6, 6-1 , 6-2, 6-3, 6-4). 202416797 18 6. The DC converter (1) of one of the preceding claims, wherein the transformer arrangement (2) has exactly three secondary windings (5) and is connected to exactly three rectifiers (6-1 , 6-2, 6-3), each rectifier (6-1 , 6-2, 6-3) being connected on its input side to one of the three secondary windings (5).

7. The DC converter (1) of the two preceding claims, wherein a first of the three rectifiers (6-3) is configured to output a first maximum DC voltage (V3), and wherein a second (6-2) and a third (6-1) of the three rectifiers (6-1 , 6-2, 6-3) are configured to output a second maximum DC voltage (Vi, V2), wherein the first maximum DC voltage (V3) is at least approximately twice as large as the second maximum DC voltage (V1, V2).

8. The DC controller (1) according to one of the two preceding claims, comprising a control unit (7) configured to generate the first and second control signals (8, 9) and thereby, in a first operating state for a low total DC voltage, to connect two of the rectifiers (6-1 , 6-2) in parallel and to deactivate the third rectifier (6-3), in a second operating state for a medium total DC voltage, to connect the two rectifiers (6-1 , 6-2) in series and to connect the rectifiers (6-1 , 6-2) connected in series to the third rectifier (6-3), and in a third operating state for a high total DC voltage, to connect the two rectifiers (6-1 , 6-2) and the third rectifier (6-3) in series.

9. The DC converter (1) of one of the preceding claims, comprising N rectifiers (6, 6-1, 6-2, 6-3, 6-4), wherein the switching matrix comprises N-1 first switches (S1-1, S1-2, S1-3), N-1 second switches (S2-1, S2-2, S2-3), and N-1 third switches (S3-1, S3-2, S3-3), wherein the N rectifiers (6, 6-1, 6-2, 6-3, 6-4) comprise a top rectifier (6-1), a bottom rectifier (6-3, 6-4), and at least one middle rectifier (6-2, 6-3), wherein each of the first switches (S1-1, S1-2, S1-3) is connected between a negative output terminal (13-n) of the bottom rectifier (6-3, 6-4) and a negative Output pole (13-n) of each rectifier (6-1 , 6-2, 6-3) from the set of at least one middle rectifier (6-2, 6-3) and the top rectifier (6-1) is switched, wherein every second switch (S2-1 , S2-2,S2-3) is connected between a positive output terminal (13-p) of the uppermost rectifier (6-1) and a positive output terminal (13-p) of each rectifier (6-2, 6-3, 6-4) from the set of at least one middle rectifier (6-2, 6-3) and the lowermost rectifier (6-3, 6-4), wherein, 202416797 19 every third switch (S3-1 , S3-2, S3-3) is connected between a positive output terminal (13-p) of one respective rectifier (6-2, 6-3, 6-4) and a negative output terminal (13-n) of one respective other rectifier (6-1 , 6-2, 6-3), with no third switch (S3-1 , S3-2, S3-3) being connected between the uppermost rectifier (6-1) and the lowermost rectifier (6-3, 6-4).

10. The DC converter (1) of one of the preceding claims, wherein the rectifiers (6, 6-1 , 6-2, 6-3, 6-4) are configured as active rectifiers (6, 6-1 , 6-2, 6-3, 6-4).

11. The DC controller (1) of one of the preceding claims, comprising a buffer capacity (12) which is connected between the poles of the DC voltage output (11) of the DC controller (1).

12. A charging device (20) for at least one electric vehicle (30) with at least one DC converter (1) according to one of the preceding claims.

13. The charging device (1) according to the preceding claim, comprising three DC converters (1) according to claim 3, wherein a first supply network connection of a first DC converter (1) of the three DC converters (1) is connected to a first phase of the supply network (3), a second supply network connection of the first DC converter (1) is connected to a second phase of the supply network (3), and a third supply network connection of the first DC converter (1) is connected to a third phase of the supply network (3), wherein a second supply network connection of a second DC converter (1) of the three DC converters (1) is connected to the first phase of the supply network (3).a first supply network connection of the second DC converter (1) is connected to the second phase of the supply network (3) and a third supply network connection of the second DC converter (1) is connected to the third phase of the supply network (3) and wherein a first supply network connection of a third DC converter (1) of the three DC converters (1) is connected to the first phase of the supply network (3), a second supply network connection of the third DC converter (1) is connected to the third phase of the supply network (3) and a third supply network connection of the third DC converter (1) is connected to a second phase of the supply network (3).

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