Active ac / DC converter with variable output voltage, and charging device for an electric vehicle having such an ac / DC converter

Abstract

The invention relates to an active AC / DC converter (1) which is designed to generate a variably specifiable DC voltage and to output same at a DC voltage output (5). The AC / DC converter (1) is equipped with: an AC input (4) for the connection of a plurality of AC phases (usually three AC phases); a transformer (7); a matrix converter (6) connected downstream of the AC input (4); and a rectifier output stage (8). The matrix converter (6) is connected or connectable to each AC phase of the plurality of AC phases via a plurality of converter inputs (21) and is designed to generate, from an AC voltage having a first frequency applied to the AC input (4), an alternating current having a second frequency different from the first frequency and to output same via a plurality of converter outputs (9) to a plurality of primary-side connections of the transformer (7). The rectifier output stage (8) is connected on the input side to a secondary-side connection of the transformer (7) and on the output side to the DC voltage output (5) and is designed to convert an output AC voltage of the transformer (7) into the variably specifiable DC voltage.

Description

[0001] 2024P15002 DE

[0002] 1

[0003] Description

[0004] Active AC / DC converter with variable output voltage and a charging device for an electric vehicle with such an AC / DC converter

[0005] Technical field

[0006] The invention relates to an active AC / DC converter with variable output voltage and a charging device for an electric vehicle with such an AC / DC converter.

[0007] Technical background

[0008] Charging the traction batteries of electric vehicles, as well as other applications, requires generating variable-amplitude DC voltages, since the most suitable charging voltage depends on the battery's current state of charge. Electrical power distribution in supply networks, however, relies on alternating current (AC), necessitating the use of AC / DC converters that transform the AC voltage from the supply network into a DC voltage with a selectable amplitude. In this process, the highest possible efficiency is desirable to minimize energy losses during rectification and voltage adaptation.

[0009] Another requirement when charging electric vehicles is galvanic isolation of the electric vehicle from the power grid and other electric vehicles connected for charging, in order to ensure maximum safety when using a charging device.

[0010] Both requirements can be met, among other things, with power electronic devices that connect an AC / DC converter, a buffer capacitor, a high-frequency inverter, a high-frequency transformer, and another AC / DC converter in series. The high-frequency transformer provides galvanic isolation, and in the case of resonant converters, the amplitude of the DC voltage generated by the device can be adjusted via the output frequency of the high-frequency inverter. The buffer capacitor, often also called a DC link capacitor, serves to smooth the DC voltage generated by the input-side AC / DC converter. (See 2024P15002 DE.)

[0011] 2. At a quasi-stationary operating point, the input-side AC / DC converter feeds as much electrical energy into the buffer capacitor as the high-frequency inverter draws from the buffer capacitor and outputs as high-frequency alternating current to the high-frequency transformer. The buffer capacitor is a large and expensive component.

[0012] The invention aims to introduce an improved active AC / DC converter. This objective is achieved through the AC / DC converter according to claim 1. Preferred embodiments of the invention are the subject matter of the dependent claims.

[0013] Summary of the invention

[0014] The invention introduces an active AC / DC converter configured to generate a DC voltage of a predefinable amplitude and output it at a DC voltage output. The AC / DC converter is equipped with an AC input for connecting a plurality of AC phases (typically three AC phases), a transformer, a matrix converter connected downstream of the AC input, and a rectifier output stage. The matrix converter is connected, or connectable, to each AC phase of the plurality of AC phases via a plurality of converter inputs and is configured to generate an AC current with a second frequency different from the first frequency from an AC voltage with a first frequency applied to the AC input and to output it via a plurality of converter outputs to a plurality of primary-side terminals of the transformer.The rectifier output stage is connected on the input side to a secondary-side connection of the transformer and on the output side to the DC voltage output and is designed to rectify an AC output voltage of the transformer and thus convert it into a DC voltage of a predeterminable amplitude.

[0015] The active AC / DC converter of the invention has the advantage that it does not require a buffer capacitor, since the (high-frequency) alternating current for controlling the transformer is generated directly by current pulses switched through the AC phases by the matrix converter. As a result, the active AC / DC converter according to the invention can be implemented with reduced costs and a smaller size compared to devices known from the prior art. 2024P15002 DE

[0016] 3

[0017] Particularly preferably, the matrix converter has a separate, switchable current path for each possible combination of a given converter input (of the plurality of converter inputs) and a given converter output (of the plurality of converter outputs). This means that a separate, switchable current path exists from each converter input to each converter output, so that current pulses can flow from one AC phase to a primary-side terminal of the transformer without impeding the flow of a corresponding current pulse from another AC phase to another primary-side terminal of the transformer. A matrix converter of this preferred type thus possesses the greatest degree of freedom in generating the AC current(s) for driving the primary side of the transformer, enabling the implementation of even complex control algorithms with small control constants.However, a potential disadvantage is the large number of switches required for the many switchable current paths.

[0018] Therefore, it can alternatively be provided that the matrix converter has at least one common current path segment for a plurality of possible current paths between a respective converter input of the plurality of converter inputs and a respective converter output of the plurality of converter outputs. In this case, not all AC phases can be switched through to a primary-side connection of the transformer simultaneously; however, such matrix converters can be implemented with a smaller number of switches.

[0019] In particular, such matrix converters could have a first connection terminal as a first common current path segment and a second connection terminal as a second common current path segment. Such matrix converters can therefore be designed symmetrically. The matrix converter of the active AC / DC converter can be equipped with a plurality of first switches, each of which is connected between a respective converter input and the first common current path segment. The first common current path segment can thus be selectively connected to one of the converter inputs, and therefore to one of the AC phases, via one of the first switches. Naturally, two first switches connected to the first common current path segment should never be switched on simultaneously, or at most only briefly, as otherwise two of the AC phases would be short-circuited.The first shared current path segment thus becomes a kind of bus, via which current pulses can be routed from the converter inputs connected to the AC phases to one of the converter outputs. See 2024P15002 DE.

[0020] 4. The matrix converter can be equipped with a plurality of second switches, each of which is connected between a respective converter input and the second common current path section. Such circuit configurations can be built completely symmetrically.

[0021] For example, at least one first switch or one second switch can comprise a transistor, a first diode, a second diode, a third diode, and a fourth diode, wherein an anode of the first diode is connected to a first intermediate node and a cathode of the first diode is connected to the respective converter input, wherein an anode of the second diode is connected to the first intermediate node and a cathode of the second diode is connected to the common current path section, wherein an anode of the third diode is connected to the common current path section and a cathode of the third diode is connected to a second intermediate node, wherein an anode of the fourth diode is connected to the respective converter input and a cathode of the fourth diode is connected to the second intermediate node, and wherein the transistor is connected between the first intermediate node and the second intermediate node.Naturally, all first and second switches are preferably constructed identically, but this is not mandatory. The configuration of the first and second switches described here allows for bidirectional operation of the active AC / DC converter, thus enabling energy feedback, for example, in a vehicle-to-grid (V2G) application. Given the steadily increasing use of renewable energy sources, such applications are expected to utilize the traction batteries of electric vehicles connected to charging stations as buffer storage for stabilizing the power grid.

[0022] Alternatively, at least one switch can comprise two antiparallel-connected unidirectionally conducting transistors. Such unidirectionally conducting transistors can be implemented either as a conventional transistor with a series-connected diode or as a transistor with an intrinsically implemented diode. An implementation with an intrinsically implemented diode is suitable for a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), where the diode can be implemented via an additional doping region around either the source or drain of the MOSFET. For this purpose, a p-type doping region is used for an n-channel MOSFET, and an n-type doping region for a p-channel MOSFET.

[0023] In a unidirectional embodiment of the active AC / DC converter according to the invention, at least one first switch can comprise a transistor, a first diode, a second diode, a third diode, and a fourth diode. An anode of the first diode is connected to a first 2024P15002 DE

[0024] 5

[0025] An intermediate node and a cathode of the first diode are connected to the respective converter input. An anode of the second diode is connected to the first common current path segment, and a cathode of the second diode is connected to the first intermediate node. An anode of the third diode is connected to a second intermediate node, and a cathode of the third diode is connected to the respective converter input. An anode of the fourth diode is connected to the second intermediate node, and a cathode of the fourth diode is connected to the second common current path segment. The transistor is connected between the first and second intermediate nodes. Such embodiments of the invention have the advantage that they can be built with a smaller number of transistors.Depending on the voltage levels prevailing in the circuit, the first switch or the first switches constructed in this way connect the first common current path section or the second common current path section to a respective alternating current phase.

[0026] Preferably, the second frequency is higher than the first frequency. The first frequency will typically be a frequency of the supply network of at least approximately 50 or 60 Hertz. The second frequency, on the other hand, can be, for example, between 20 and 100 kilohertz. The second frequency is neither a fixed value nor is it in a fixed ratio to the first frequency. Rather, the second frequency is the control variable used to determine the amplitude of the DC voltage generated by the active AC / DC converter according to the invention. In other words, the amplitude of the DC voltage is a function of the second frequency.

[0027] The active AC / DC converter is preferably equipped with a primary-side resonant circuit connected between the majority of converter outputs and the majority of primary-side terminals of the transformer. This resonant circuit is designed to oscillate resonantly at the second frequency upon excitation by the matrix converter. The use of a primary-side resonant circuit improves the efficiency of the system and reduces electromagnetic radiation as well as transformer losses due to higher-frequency signal components.

[0028] Similarly, a secondary-side resonant circuit arrangement can be provided between the secondary-side connection of the transformer and the rectifier output stage. Such a secondary-side resonant circuit arrangement offers corresponding advantages during regenerative operation, i.e., when excited by the rectifier output stage, which operates as an inverter in the case of regenerative operation, as a primary-side resonant circuit.

[0029] 6

[0030] Resonance circuit arrangement. The primary-side and secondary-side resonance circuit arrangements can act together as a distributed resonance circuit arrangement.

[0031] Preferably, the active AC / DC controller is designed for three-phase operation on the supply network side, i.e., for three alternating current phases.

[0032] The transformer can, for example, be designed with three phases on the primary side, such as in a star or delta configuration. In such a case, any primary-side resonant circuit arrangement will also be three phases, i.e., equipped with three resonant circuits.

[0033] The transformer can have a winding ratio of 1:1 or 1:x, where x is preferably greater than 1. If x is greater than 1, higher DC voltages can be generated, which makes the active AC / DC converter according to the invention particularly suitable for the rapid charging of traction batteries with high open-circuit voltages.

[0034] A buffer capacitor is preferably connected downstream of the rectifier output stage. Such a buffer capacitor serves to smooth the variably adjustable DC voltage.

[0035] A secondary aspect of the invention relates to a charging device for charging an electric vehicle, which includes an active AC / DC converter according to the invention.

[0036] Brief description of the images

[0037] The invention will be described in more detail below with reference to illustrations of exemplary embodiments. These show:

[0038] Fig. 1 shows a first embodiment of an active AC / DC converter according to the invention;

[0039] Fig. 2 shows a first embodiment of a matrix converter as it can be used in the active AC / DC controller according to the invention;

[0040] Fig. 3 shows a second embodiment of a matrix converter as it can be used in the active AC / DC controller according to the invention; 2024P15002 DE

[0041] 7

[0042] Fig. 4 shows a second embodiment of a bidirectional switch, as it can be used in the matrix converter of the active AC / DC controller according to the invention;

[0043] Fig. 5 shows a third embodiment of a bidirectional switch, as it can be used in the matrix converter of the active AC / DC controller according to the invention;

[0044] Fig. 6 shows a third embodiment of a matrix converter that can be used in the active AC / DC controller according to the invention;

[0045] Fig. 7 shows a second embodiment of the active AC / DC converter according to the invention; and

[0046] Fig. 8 shows a third embodiment of the active AC / DC converter according to the invention.

[0047] Detailed character description

[0048] Fig. 1 shows a first embodiment of an active AC / DC converter 1 according to the invention. The active AC / DC converter 1 of Fig. 1 has a particularly simple and therefore cost-effective design. A matrix converter 6 is connected via an AC input 4 to a power supply network 2, from which the active AC / DC converter 1 can draw electrical power and convert it into a variably preset DC voltage. With this DC voltage, the active AC / DC converter 1 can, for example, charge a battery 3 connected to a DC voltage output 5. In a bidirectional design of the active AC / DC converter 1, a regenerative braking operation can be provided, in which the active AC / DC converter 1 draws electrical power from the battery 3 and feeds it back into the power supply network 2.

[0049] The matrix converter 6 serves to generate higher-frequency current pulses from the alternating current phases of a first frequency (typically 50 or 60 Hertz) applied to the alternating current input 4. These pulses then generate an alternating current of a second frequency, which is different from the first frequency and usually higher, in particular at least two decades higher. The matrix converter does not include a buffer capacitor, such as those connected in a so-called back-to-back configuration between a rectifier and an inverter in numerous inverters known in the prior art. By omitting such a buffer capacitor, the active AC / DC converter 1 according to the invention can be manufactured with reduced costs and a smaller footprint. 2024P15002 DE

[0050] 8. This will be achieved. By eliminating the buffer capacitor, which is usually implemented as an electrolytic capacitor, the average lifespan of the device also increases.

[0051] A transformer 7 is connected downstream of the matrix converter 6. In the embodiment shown in Fig. 1, the primary winding of the transformer acts as a filter for the current pulses generated by the matrix converter 6, thus generating a sinusoidal alternating current of the second frequency. In the example shown, the transformer is configured with three phase inputs; however, configurations with a different number of connections could also be used.

[0052] The transformer 7 transfers the alternating current to its secondary side and outputs it to a rectifier output stage 8, which rectifies the alternating current and thereby generates the DC voltage with a predefinable amplitude. The amplitude of the DC voltage generated by the rectifier output stage 8 is determined by the amplitude of the alternating current generated by the components upstream of the rectifier output stage 8, or by the resulting AC voltage. In a unidirectional design of the active AC / DC converter 1, the rectifier output stage 8 can be constructed with passive elements such as diodes, or, particularly in bidirectional operation, with active elements such as transistors. Using active elements reduces the power dissipation of the rectifier output stage 8; however, this requires increased complexity for controlling the active elements.The rectifier output stage 8 can also contain one or more smoothing capacitors that smooth an AC component of the rectified output voltage.

[0053] The transformer 7 can generally have a turns ratio of 1:1 or a different ratio. In particular, the transformer 7 can be configured to transform a comparatively low peak voltage provided by the supply network 2 to a higher voltage level in order to provide a charging voltage suitable even for large batteries 3 with a high open-circuit voltage. For example, the transformer can be configured to transform alternating currents or voltages generated by the matrix converter from a 400-volt three-phase network to a level of 800 volts and higher.

[0054] Fig. 2 shows a first embodiment of a matrix converter 6, as it can be used in the active AC / DC controller 1 according to the invention. The matrix converter 6 of Fig. 2 is designed such that it can be used for each combination of one of the converter inputs 21 (in the example 2024P15002 DE).

[0055] The matrix converter 6 (three converter inputs 21 for a three-phase supply network) has its own current path with a corresponding first switch 10 for each converter output 9. In the example shown, three converter outputs 9 are provided, allowing for a simple connection to a three-phase transformer 7. However, other numbers of converter outputs, such as two or more, are also possible. Due to the three converter inputs 21 and the three converter outputs 9, 3 x 3 = 9 first switches 10 are required. This illustrates that the matrix converter 6, with its own current path for each possible combination of converter inputs 21 and converter outputs 9, requires a comparatively high number of first switches 10 and therefore increased implementation effort.However, it has the advantage that a current pulse from more than one AC phase can be switched simultaneously to a respective converter output 9. This allows for a higher output power of the active AC / DC converter. The first switches 10 are bidirectional. Given the desirable high switching speed, semiconductor switches, such as silicon carbide transistors, are generally suitable for this purpose.

[0056] Fig. 3 shows a second embodiment of a matrix converter 6, as it can be used in the active AC / DC controller 1 according to the invention. The matrix converter 6 of this embodiment can be implemented with a smaller number of first switches 10, which enables cost savings. In the example shown with three converter inputs 21 and three converter outputs 9, only six first switches 10 are required instead of the nine first switches 10 of the embodiment of Fig. 2. Three first switches 10 are connected between each associated converter input 21 and one of two common current path sections 11-1, 11-2. The two common current path sections 11-1, 11-2 serve to provide the necessary current paths for the current flow to a converter output 9 and back from a converter output 9 to a converter input 21. To select a converter output 9, the matrix converter 6 shown in Fig.Three second switches 12 are provided, namely one second switch 12 between each of the common current path sections 11-1, 11-2 and each converter output 9. In the example shown with three converter outputs 9, there are therefore six second switches 12. Although this increases the total number of switches to twelve, exceeding the number of first switches 10 in the embodiment of Fig. 2, the matrix converter 6 of Fig. 3 can usually be implemented at a lower cost, since slower and therefore less expensive semiconductor switches, such as ordinary (silicon) IGBTs (Insulated Gate Bipolar Transistors), can be used as the second switches. 2024P15002 DE.

[0057] 10

[0058] The matrix converter 6 of Fig. 3 is designed to be bidirectional, allowing power to flow from the converter inputs 21 to the converter outputs 9 or in the opposite direction. This enables the active AC / DC converter 1 to operate bidirectionally, allowing electrical energy to be fed back into the supply network 2. However, the matrix converter 6 can also be implemented unidirectionally, as illustrated by an example below.

[0059] In the embodiment shown in Fig. 3, the first switches 10 each consist of a transistor 14 and four diodes 15. Two diodes 15 are connected in series in opposite directions, and these series connections are in turn connected in parallel in opposite directions. This results in two current paths, in each of which one diode 15 is always reverse-biased. The transistor 14 is connected between the two current paths, so that when the transistor 14 is switched on, current can flow through one diode 15 in each current path and through the transistor 14 itself. A so-called body or substrate diode (not shown for the first switches 10) of the transistor 14 is connected such that its forward direction is opposite to that of the diodes 15 in these two current paths. This allows the first switch 10 to be bidirectionally reverse-biased, and current can only flow when the transistor 14 is switched on.

[0060] The second switches 12 are shown here as a parallel circuit consisting of a transistor 14 and a diode 15. When using MOSFETs, the diode 15 can be implemented as a body or substrate diode as part of the transistor 14 itself.

[0061] Fig. 4 shows a second embodiment of a bidirectional switch 13, as it can be used in the matrix converter 6 of the active AC / DC converter 1 according to the invention. The second embodiment corresponds functionally to the first example, which is shown in Fig. 3 as the first switch 10 and part of the matrix converter 6 shown there, but has a different construction. The bidirectional switch 13 has two control electrodes 17, which can either selectively switch the bidirectional switch 13 in only one of the two possible directions or be connected to each other to allow the bidirectional switch 13 to be controlled by a single control signal. The control electrodes 17 are each connected to gate electrodes of transistors 14, which can be implemented as silicon carbide transistors or as conventional silicon-based IGBTs.The transistors 14 are connected in series in opposite directions, so that – depending on the polarity of a voltage applied between the two terminals 16 of the bidirectional switch 13 – one of the substrate diodes 15 of the two transistors 14 is always reverse-biased. If the transistor 14 whose substrate diode 15 is reverse-biased is switched on, current 2024P15002 DE can flow.

[0062] Current flows through the bidirectional switch 11 in the opposite direction to that of the blocking substrate diode 15. If no transistor 14 is switched on, the bidirectional switch 13 is blocked.

[0063] Fig. 5 shows a third embodiment of a bidirectional switch 13, as it can be used in the matrix converter 6 of the active AC / DC converter 1 according to the invention. The bidirectional switch 13 of Fig. 15 again has two transistors 14 and two diodes 15, the diodes 15 being connected in series with the transistors 14. The diodes 15 are connected, if present, oppositely to a substrate diode of the respective transistor 14, so that current can only flow through each transistor 14 when the transistor is switched on.

[0064] 14 is switched on. The diodes simultaneously determine the direction in which this current can flow. To allow bidirectional current flow, two such branches, each consisting of a transistor 14 and a diode 15, are connected antiparallel to each other. The diodes

[0065] When using MOSFETs as transistors 14, as described above, the diodes 15 can be implemented as part of the transistors 14. Due to the threshold voltage of the diodes 15, the power dissipation in this switch configuration may be higher than in the embodiment shown in Fig. 4. Furthermore, the control circuitry may be more complex because the gates of the two transistors 14 are driven with different potentials.

[0066] The embodiments of bidirectional switches 13 shown in Figures 4 and 5 can, for example, be used as first switches 10 in the illustrated embodiments of matrix converters 6, in the case of the embodiment of Fig. 3 instead of the switch configuration of the first switches 10 shown there.

[0067] Fig. 6 shows a third embodiment of a matrix converter 6, which can be used in the active AC / DC converter 1 according to the invention. In this embodiment, with three converter inputs 21 and three converter outputs 9, only three first switches 10 are required. However, the matrix converter 6 of this embodiment can only be operated unidirectionally; power flow is only possible from the supply network 2 to the DC voltage output 5, but no regenerative braking is possible. Here, a first switch 10 is connected between the two common current path sections 11-1 and 11-2. When transistor 14 is switched on, it can allow either a current flow from an AC input 4 through the third diode from the top, transistor 14, and the uppermost diode to the upper common current path section 11, or from the lower current path section 11 through the lowest diode, through transistor 14, and through the second diode from the top to the AC input 4.The matrix converter 6 of Fig. 6 can therefore be built with a minimal number of transistors 14 and thus be particularly cost-effective. 2024P15002 DE.

[0068] 12

[0069] Fig. 7 shows a second embodiment of the active AC / DC converter 1 according to the invention. The second embodiment is fundamentally similar to the first embodiment shown in Fig. 1, so that what was said there also applies to this embodiment unless otherwise stated. The second embodiment differs from that of Fig. 1 primarily by a mains filter 18, which is connected between the AC inputs 4 and the matrix converter 6 and is intended to reduce any feedback from the switching operations in the matrix converter 6 to the supply network 2. For illustrative purposes only, the transformer 7 is shown here as a transformer with three primary and three secondary windings, with the primary and secondary windings shown connected in a star configuration. Naturally, at least one side could also be connected, for example, in a delta configuration.Numerous suitable transformer configurations are known in the prior art. It is also possible to implement the transformer 7 with a different number of windings and connections, which entails corresponding modifications to the upstream and downstream components such as the matrix converter 6 and the rectifier output stage 8.

[0070] Fig. 8 shows a third embodiment of the active AC / DC converter 1 according to the invention. The third embodiment is fundamentally similar to the second embodiment shown in Fig. 7, so that what is stated there also applies to this embodiment unless otherwise stated. The third embodiment differs from the second by the primary-side and secondary-side resonant circuit arrangements 19, 20, of which only one primary-side resonant circuit arrangement 19 may be provided. The resonant circuit arrangements 19, 20 have a corresponding number of resonant circuits as the transformer 7 has connections. The primary-side resonant circuits are excited to oscillate by current pulses from the matrix converter 6 and oscillate at or near a resonant frequency that is identical for all resonant circuits. They are driven such that they oscillate out of phase with each other; with three resonant circuits, the phase shift is 360 / 3 = 120 degrees.The sinusoidal oscillations generated by the resonant circuit can be transmitted to the secondary side of the transformer 7 with good efficiency. The resonant circuit reduces the high-frequency signal components of the current pulses from the matrix converter 6 injected into the transformer 7, which are problematic with regard to reduced efficiency and disruptive electromagnetic radiation. A secondary-side resonant circuit arrangement 20 can be used in a similar manner, which, together with the primary-side resonant circuit arrangement 19, forms a shared resonant circuit arrangement 2024P15002 DE between the primary and secondary sides of the transformer 7.

[0071] 13 functions. Such a split resonant circuit arrangement with both a primary-side resonant circuit arrangement 19 and a secondary-side resonant circuit arrangement 20 is particularly advantageous for an active AC / DC converter 1 intended for bidirectional operation, since the advantages of improved efficiency and reduced electromagnetic radiation can also be achieved for regenerative operation.

[0072] The invention has been explained in more detail with reference to illustrations of exemplary embodiments. These exemplary embodiments serve only to improve understanding and are not intended to limit the invention, which is defined exclusively by the following patent claims.

[0073] 2024P15002 DE

[0074] 14

[0075] Reference symbol list

[0076] 1 active AC / DC converter

[0077] 2 Supply network

[0078] 3 batteries

[0079] 4 AC inputs

[0080] 5 DC voltage output

[0081] 6 matrix inverters

[0082] 7 T transformer

[0083] 8 Rectifier output stage

[0084] 9 Converter output

[0085] 10 first switch

[0086] 11-1 first common current path section

[0087] 11-2 second common current path section

[0088] 12 second switch

[0089] 13 bidirectional switches

[0090] 14 transistors

[0091] 15 diode

[0092] 16 Terminal

[0093] 17 Control electrode

[0094] 18 mains filters

[0095] 19 primary-side resonant circuit arrangement

[0096] 20 secondary-side resonant circuit arrangement

[0097] 21 Converter input

Claims

2024P15002 DE 15 Patent claims 1. An active AC / DC converter (1) configured to generate a DC voltage of a predefinable amplitude and output it at a DC voltage output (5), comprising an AC input (4) for connecting a plurality of AC phases, a transformer (7), a matrix converter (6) connected downstream of the AC input (4), which is connected or connectable to each AC phase of the plurality of AC phases via a plurality of converter inputs (21) and which is configured to generate an AC current with a second frequency different from the first frequency from an AC voltage applied to the AC input with a first frequency and to output it via a plurality of converter outputs (9) to a plurality of primary-side terminals of the transformer (7),as well as a rectifier output stage (8) connected on the input side to a secondary-side connection of the transformer (7) and on the output side to the DC voltage output (5), which is designed to rectify an AC output voltage of the transformer (7) and thus convert it into a DC voltage of a predefinable amplitude.

2. The active AC / DC converter (1) of the preceding claim, wherein the matrix converter (6) has a separate and switchable current path for each possible combination of a respective converter input (21) of the plurality of converter inputs (21) and a respective converter output (9) of the plurality of converter outputs (9).

3. The active AC / DC converter (1) of claim 1, wherein the matrix converter (6) has at least one common current path section (11-1 , 11-2) for a plurality of possible current paths between a respective converter input (21) of the plurality of converter inputs (21) and a respective converter output (9) of the plurality of converter outputs (9).

4. The active AC / DC converter (1) of the preceding claim, wherein the matrix converter (6) has a first connecting pole (11-1) as a first common current path section (11-1) and a second connecting pole (11-2) as a second common current path section (11-2).

5. The active AC / DC converter (1) of the preceding claim, comprising a plurality of first switches (10), of which a respective first switch (10) is connected between a respective converter input (21) and the first common current path section (11-1). 2024P15002 DE 16 6. The active AC / DC converter (1) of the preceding claim, comprising a plurality of second switches (12), one of which is connected between a respective converter input (21) and the second common current path section (11-2).

7. The active AC / DC converter (1) of the preceding claim, wherein at least a first switch (10) or a second switch (12) comprises a transistor (14), a first diode (15), a second diode (15), a third diode (15), and a fourth diode (15), wherein an anode of the first diode (15) is connected to a first intermediate node and a cathode of the first diode (15) is connected to the respective converter input (21), wherein an anode of the second diode (15) is connected to the first intermediate node and a cathode of the second diode (15) is connected to the common current path section (11-1, 11-2), wherein an anode of the third diode (15) is connected to the common current path section (11-1, 11-2) and a cathode of the third diode (15) is connected to a second intermediate node, wherein an anode of the fourth diode (15) is connected to the respective converter input (21), and a cathode of the fourth diode (15) is connected to the second intermediate node,and wherein the transistor (14) is connected between the first intermediate node and the second intermediate node.

8. The active AC / DC converter (1) of claim 6, wherein at least one first switch (10) comprises two antiparallel connected unidirectionally conducting transistors (14).

9. The active AC / DC converter (1) of claim 5, wherein at least one first switch (10) comprises a transistor (14), a first diode (15), a second diode (15), a third diode (15) and a fourth diode (15), wherein an anode of the first diode (15) is connected to a first intermediate node and a cathode of the first diode (15) is connected to the respective converter input (21), wherein an anode of the second diode (15) is connected to the first common current path section (11-1) and a cathode of the second diode (15) is connected to the first intermediate node, wherein an anode of the third diode (15) is connected to a second intermediate node and a cathode of the third diode (15) is connected to the respective converter input (21), wherein an anode of the fourth diode (15) is connected to the second intermediate node and a cathode of the fourth diode (15) is connected to the second common current path section (11-2),and wherein the transistor (14) is connected between the first intermediate node and the second intermediate node.

10. The active AC / DC converter (1) of any of the preceding claims, wherein the second frequency is higher than the first frequency. 2024P15002 DE 17 11. The active AC / DC converter (1) of the preceding claim, wherein the second frequency is between 20 and 100 kilohertz.

12. The active AC / DC converter (1) of any of the preceding claims, with a frequency between the A primary-side resonant circuit arrangement (19) is switched between the majority of converter outputs (9) and the majority of primary-side terminals of the transformer (7), and is designed to oscillate resonantly at the second frequency when excited by the matrix converter (6).

13. The active AC / DC converter (1) of any one of the preceding claims, comprising a secondary-side resonant circuit arrangement (20) connected between the secondary-side terminal of the transformer (7) and the rectifier output stage (8).

14. A charging device for charging an electric vehicle, characterized by an active AC / DC converter (1) according to any one of the preceding claims.

Images