Power supply system for a vehicle and method for controlling a power supply system for a vehicle

Abstract

The invention relates to a power supply system (1, 1', 1") for an electric vehicle, comprising a first AC voltage connection (1a) and a second AC voltage connection (1b), which are designed to be connected to an AC voltage source. Furthermore, the power supply system (1, 1', 1") comprises a power converter arrangement (1000) with a symmetrical power converter circuit (10, 10', 10") with power factor correction, wherein the power converter circuit (10, 10', 10") is connected to the first AC voltage connection (1a) via at least one first input connection (10a) and to the second AC voltage connection (1b) via at least one second input connection (10b) and is designed to convert the AC voltage applied between the first AC voltage connection (1a) and the second AC voltage connection (1b) into a first DC voltage (U2a), which is applied between a first output connection (11a) of the power converter circuit (10,10', 10") and a center terminal (30), and a second DC voltage (U2b) present between a second output terminal (11b) of the converter circuit (10, 10', 10") and the center terminal (30), and a first capacitor (31) connected between the first output terminal (11a) and a center terminal (30), and a second capacitor (32) connected between the second output terminal (10b) and the center terminal (30). The power supply system (1, 1', 1") is further configured to supply a load (50) connected between the first AC voltage terminal (1a) and the center terminal (30) with a predetermined AC voltage during a charging process in which the first AC voltage terminal (1a) and the second AC voltage terminal (1b) are connected to an external voltage source.

Description

The present invention relates to a power supply system for a vehicle and to a method for controlling a power supply system for a vehicle, and to a computing unit and a computer program for carrying it out.BACKGROUND OF THE INVENTIONIn integrated charging devices (so-called on-board chargers) for electric vehicles (fully electric or hybrid), the AC voltage of the grid is converted into a DC voltage in order to charge the traction battery of the electric vehicle. For example, the on-board charger can be constructed in two stages. The first stage may be a rectifier, which may be equipped with a power factor correction (PFC), for the in-phase rectification of the input AC voltage. The second stage may be a DC-DC converter for converting the rectified input voltage into the battery voltage of the traction battery. Alternatively, single-stage concepts are also possible, which combine both functions in a rectifier stage.On-board chargers can be operated either in regions with three-phase AC networks (e.g. 22kW in EU and China) or in regions with single-phase AC networks (e.g. North America and Japan). Furthermore, the nominal voltage of the single-phase alternating voltage grid in North America can be an alternating voltage with an amplitude of 120 V or 240 V depending on the performance of the connection.On-board chargers are also intended to provide, in part as an additional function, the alternating voltage for a socket in the car (vehicle-to-load, V2L). In some vehicles, this function need only be provided when the vehicle is not in charging operation. In a bidirectional embodiment of rectifier and DC-DC converter, the hardware installed for charging operation can provide this function (possibly with further components for protection / monitoring). In other vehicles, however, the function should also be available in the charging mode.Disclosure of the InventionAccording to the invention, a power supply system for a vehicle and a method for controlling a power supply system for a vehicle, and a computing unit and a computer program for carrying it out are proposed having the features of the independent patent claims. Advantageous embodiments are the subject matter of the dependent claims and of the following description.The invention is based on a power supply system for a vehicle, which has a first AC voltage connection and a second AC voltage connection, which are configured to be connected to an AC voltage source, via which the vehicle can be supplied with an AC voltage. Furthermore, the power supply system comprises a power converter arrangement with a balanced power converter circuit which is connected via a first input terminal to the first AC voltage terminal and via a second input terminal to the second AC voltage terminal. The converter circuit is configured to convert the alternating voltage present at the first alternating voltage connection and the second alternating voltage connection into a first direct voltage and a second direct voltage, wherein the first direct voltage is present between a first output connection of the converter circuit and a center connection and the second direct voltage is present between a second output connection of the converter circuit and the center connection. The first and the second direct voltage are in particular polarized in opposite directions to one another. The converter arrangement further comprises a first capacitor connected between the first output terminal and the center terminal and a second capacitor connected between the second output terminal and the center terminal.The core of the invention consists in that, due to the symmetrical structure of the rectifier of the converter circuit having a central connection, a further AC voltage is set or adjusted between the first AC voltage connection and the central connection in addition to the input voltage. This voltage may be supplied as a vehicle-to-load voltage from the power supply system.In detail, the power supply system is configured to supply a load, in particular a load connected to a socket of the vehicle, such as an electrical load, which is connected between the first AC voltage connection and the central connection, with a predefined AC voltage during a charging process in which the power supply system is connected to the external AC voltage source via the AC voltage connections. For this purpose, the voltage level of the central connection is adjusted by modulation of the alternating voltage present at the first alternating voltage connection and the alternating voltage present at the second alternating voltage connection. During the charging process, a traction battery of the vehicle is also charged using the first DC voltage and / or second DC voltage.As a result, the vehicle-to-load function can be provided in the load mode without additional components being necessary, as a result of which costs can be saved during production.Furthermore, the voltage provided as a vehicle-to-load voltage can be set to a predefined voltage, for example an AC voltage of 120 V, by setting the voltage level of the central connection independently of the mains connection.In addition, the symmetrical structure of the rectifier makes it possible to dispense with an unfolder circuit which switches between the positive and negative DC voltage potentials at the zero crossing and thus causes disadvantages with regard to the common mode emissions and insulation distances of the rectifier. This makes it possible to save costs during production and to reduce the maintenance or repair outlay.In one embodiment, the converter circuit comprises a plurality of first input terminals, each of the first input terminals being connected to the first AC voltage terminal, respectively. Furthermore, the converter circuit comprises a plurality of second input terminals, wherein each of the second input terminals is respectively connected to the second AC voltage terminal. This allows the power supply system to be connected to a two-phase AC voltage source. The use of two first input connections and two second input connections is particularly preferred. As a result, the power supply system can optionally also be connected to a three-phase alternating voltage source.In one embodiment, the power supply system further comprises a third AC voltage connection and a fourth AC voltage connection, which are configured to be connected to the external AC voltage source. The power converter circuit of the power supply system further has two first input terminals and two second input terminals. The converter arrangement further comprises a first changeover switch and a second changeover switch. The first changeover switch is arranged between the two first input terminals, the first AC voltage terminal and the third AC voltage terminal and is configured to connect, when the power supply system is connected to a two-phase external AC voltage source, the two first input terminals to the first AC voltage terminal, and, when the power supply system is connected to a three-phase external AC voltage source, connect one of the two first input terminals to the first AC voltage terminal and connect the other of the two first input terminals to the third AC voltage terminal. Analogously, the second changeover switch is arranged between the two second input terminals, the second AC voltage terminal and the fourth AC voltage terminal and is configured, when the power supply system is connected to a two-phase external AC voltage source, to connect the two second input terminals to the second AC voltage terminal and, when the power supply system is connected to a three-phase external AC voltage source, to connect one of the two second input terminals to the second AC voltage terminal and to connect the other of the two second input terminals to the fourth AC voltage terminal. The power supply system is configured such that an AC voltage of a two-phase AC voltage source is present in particular between the first and the third AC voltage connection and an AC voltage of a three-phase AC voltage is present at the four AC voltage connections. The first and second changeover switches are in particular also configured to detect whether a two-phase or three-phase alternating voltage is present and to automatically provide the associated connection between the alternating voltage connections and the input connections.As a result, the power supply system can be connected to both a two-phase and a three-phase alternating voltage source without additional components being necessary in the converter circuit. In particular, manufacturing costs for the power supply system can thereby be reduced.In one embodiment, the power converter arrangement furthermore comprises at least one first inductance which is arranged in each case between one of the at least one first input terminal of the power converter circuit and the AC voltage terminal to which the respective first input terminal is connected, and at least one second inductance which is arranged in each case between one of the at least one second input terminal of the power converter circuit and the AC voltage terminal to which the respective second input terminal is connected. This means that if the converter circuit has only a first and a second input terminal, a first inductance and a second inductance are present. The first inductance is connected between the first input terminal and the first AC voltage terminal, while the second inductance is connected between the second input terminal and the second AC voltage terminal. If, on the other hand, the converter circuit has, for example, two first input terminals and two second input terminals, which are each connected to the first AC voltage terminal or the second AC voltage terminal or first to fourth AC voltage terminals, two first inductances and two second inductances are used. The two first inductances are arranged here in particular behind the changeover switch, at which the connection to the first AC voltage connection is divided between the two first input connections, such that only one first inductance is arranged between each of the first input connections and the first AC voltage connection. The same applies to the second inductances. If the power supply system further comprises a third and fourth AC voltage connection and two first and two second input connections, wherein one of the first input connections is connected to the first AC voltage connection and the other of the first input connections is connected to the third AC voltage connection and one of the second input connections is connected to the second AC voltage connection and the other of the second input connections is connected to the fourth AC voltage connection, a first inductance is arranged between each of the first input connections and the corresponding AC voltage connection and a second inductance is arranged between each of the second input connections and the corresponding AC voltage connection. The at least one first inductance and / or the at least one second inductance can be coils, for example.By using inductances, the ripple of the respective input voltage and, associated therewith, the ripple of the output voltage can be reduced and the power factor can be improved.In one embodiment, the converter circuit further comprises at least one first drivable semiconductor switching element, which is arranged between one of the at least one first input terminal and the first output terminal, and at least one second drivable semiconductor switching element, which is arranged between the same of the at least one first input terminal and the second output terminal. Furthermore, the power converter circuit comprises at least one third drivable semiconductor switching element which is arranged between one of the at least one second input terminal and the first output terminal, and at least one fourth drivable semiconductor switching element which is arranged between the same of the at least one second input terminal and the second output terminal. If the converter circuit has a single first input terminal and a single second input terminal, the converter circuit also comprises a single first to fourth drivable semiconductor switching element. In the case of more than one first and / or second input terminal, the number of first or second drivable semiconductor switching elements corresponds to the number of first input terminals, and in each case a first and a second drivable semiconductor switching element is connected to exactly one of the first input terminals. The same applies to the third or fourth drivable semiconductor switching element.This provides a symmetrical converter circuit in a simple manner, which generates two DC voltages from an applied AC voltage, which voltages are applied between an output terminal and the central terminal.In one embodiment, the converter circuit further comprises a central output terminal which is connected to the central terminal, and additionally a fifth drivable semiconductor switching element and a sixth drivable semiconductor switching element which are connected in series between one of the at least one first input terminal and the central terminal, and / or a seventh drivable semiconductor switching element and an eighth drivable semiconductor switching element which are connected in series between one of the at least one second input terminal and the central terminal.By using the additional semiconductor switching elements connected to the central terminal, the shape of the DC voltage can be further improved, whereby in particular the use of further filters to smooth the DC voltage can be dispensed with.The invention further relates to a vehicle comprising a charging connection configured to connect the vehicle to an external AC voltage source, and a power supply system according to any one of the preceding claims, wherein the first AC voltage connection and the second AC voltage connection of the power supply system are connected to corresponding connections of the charging connection. In the case of a three-phase alternating voltage, both the charging connection and the power supply system have four connections. In this case, the four terminals of the charging terminal can be connected to the terminals of the external AC voltage source, and the four AC voltage terminals of the power supply system can each be connected to the corresponding terminal of the charging terminal.The invention further relates to a method for operating a power supply system as illustrated in the preceding embodiments, wherein the voltage level of the central connection is controlled in such a way that a predefined alternating voltage is present at the load. The voltage level of the central connection is controlled in particular by modulation of the alternating voltage present at the first alternating voltage connection and / or of the alternating voltage present at the second alternating voltage connection. Preferably, a downstream adjustment of the voltage level of the center connection takes place by means of a downstream DC / DC converter, the input of which is connected to the center tap.A computing unit according to the invention, e.g. a control unit of a power supply system, is configured, in particular by programming, to carry out a method according to the invention.The implementation of a method according to the invention in the form of a computer program or computer program product with program code for carrying out all method steps is also advantageous since this causes particularly low costs, in particular if an executing control device is also used for further tasks and is therefore present in any case. Finally, a machine-readable storage medium is provided with a computer program stored thereon, as described above. Suitable storage media or data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, such as hard disks, flash memories, EEPROMs, DVDs, among others. Download of a program via computer networks (Internet, intranet, etc.) is also possible. Such a download can be effected in a wired or wired or wireless manner (e.g. via a WLAN network, a 3G, 4G, 5G or 6G connection, etc.).Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.The invention is schematically illustrated in the drawing on the basis of exemplary embodiments and is described below with reference to the drawing.Brief Description of the DrawingsFIG. 1 shows a power supply system according to an embodiment of the invention, FIG. 2 shows a power supply system according to a further embodiment of the invention, FIG. 3 shows a power supply system according to a further embodiment of the invention, FIG. 4 shows a converter circuit that can be used in a power supply system according to an embodiment of the invention, and FIG. 5 shows a converter circuit that can be used in a power supply system according to a further embodiment of the invention.Embodiment(s) of the InventionFIG. 1 shows a power supply system 1 according to an embodiment of the invention. The power supply system 1 comprises a first AC voltage connection 1 aand a second AC voltage connection 1 b, via which the power supply system 1 can be connected to an external AC voltage source. The external AC voltage source can be, for example, a single-phase AC voltage source.The power supply system 1 further comprises a converter arrangement 1000 having a converter circuit 10. The first input terminal 10 ais conductively connected to the first AC voltage terminal 1 aof the power supply system 1 and the second input terminal 10 bis conductively connected to the second AC voltage terminal 1 bof the power supply system 1. A first inductance 21 is connected between the first AC voltage terminal 1 aand the first input terminal 10 a. A second inductance 22 is connected between the second AC voltage terminal 1 band the second input terminal 10 b. The inductance 21, 22 serves to reduce the ripple of the alternating voltage present between the alternating voltage terminals 1 a, 1 b.The converter circuit 10 further comprises a first output terminal 11 aand a second output terminal 11 b, via which the converter circuit 100 outputs a first DC voltage U 2 aand a second DC voltage U 2 b. Furthermore, a first capacitor 31 and a second capacitor 32 are connected in series between the first output terminal 11 aand the second output terminal 11 band have a central terminal 30 between the first capacitor 31 and the second capacitor 32. The first DC voltage U 2 acan be tapped between a first DC voltage connection 100 aof the converter arrangement 1000 and the central connection 30, while the second DC voltage U 2 bcan be tapped between a second DC voltage output connection 100 bof the converter arrangement 1000 and the central connection 30.Furthermore, a load 50 is arranged between the first AC voltage connection 1 aand the central connection 30. The alternating voltage U0is present at the load 50. The load 50 may be, for example, an electric device such as a refrigerator connected to a power outlet located, for example, in the vehicle interior.The alternating voltage U0applied to the load 50 can be adjusted in particular by modulation of the alternating voltage applied to the first alternating voltage connection 1 aand / or the alternating voltage applied to the second alternating voltage connection 1 b. As a result, regardless of the amplitude of the input voltage, which may be 120 V or 240 V in North America, for example, the alternating voltage present at the load 50 may always have a predefined amplitude, for example 120 V.FIG. 2 shows a power supply system 1' according to a further embodiment of the invention. The same reference numerals designate the same components, so that a detailed explanation is omitted and reference is made to the explanations relating to FIG. 1.In contrast to the converter circuit 10 of FIG. 1, the power conversion circuit 10' of FIG. 2 has two first input terminals 10a and two second input terminals 10b, each of the first input terminals 10a being connected to the first AC voltage terminal 1a and each of the second input terminals being connected to the second AC voltage terminal 1b. A first inductance 21 is connected between each of the first input terminals 10 aand the first AC voltage terminal 1 a. Furthermore, a second inductance 22 is also connected in each case between each of the second input terminals 10 band the second AC voltage terminal 1 b.In addition, the converter circuit 10' has a center output terminal 11c connected to the center terminal 30. As a result, the converter circuit 10' can be additionally connected to the voltage level of the center terminal 30.In the case of a three-phase AC power source, as shown in FIG. 3, the power supply system 1" includes a third AC terminal 1 cand a fourth AC terminal 1 din addition to the first AC terminal 1 aand the second AC terminal 1 b. Here, the two first input terminals 10 aand the two second input terminals 10 bare not connected in parallel to the first AC voltage terminal 1 aand the second AC voltage terminal 1 b, respectively, but each of the input terminals 10 a, 10 bof the converter circuit 10 is connected to one of the four AC voltage terminals. Through the third AC voltage terminal 1 cand the fourth AC voltage terminal 1 d, the power supply system 1" can be connected to a three-phase AC voltage source.In this case, one of the first input connections 10 ais connected to the first AC voltage connection 1 aand the other first input connection 10 ais connected to the third AC voltage connection 1 c, while one of the two second input connections 10 bis connected to the second AC voltage connection 1 band the other second input connection 10 bis connected to the fourth AC voltage connection 1 d. Furthermore, a first inductance 21 is connected between each of the first input terminals 10 aand the corresponding AC voltage terminal 1 a, 1 cto which the first input terminal 10 ais connected. Analogously, a second inductance 22 is connected between each of the second input terminals 10 band the corresponding AC voltage terminal 1 b, 1 dto which the second input terminal 10 bis connectedFor this purpose, no further components are necessary in the converter arrangement 1000'. Instead, one of the two first input terminals 10a is connected to the first AC voltage terminal 1a and the other of the two first input terminals 10a is connected to the third AC voltage terminal 1c. Furthermore, one of the two second input terminals 10 bis connected to the second AC voltage terminal 1 band the other of the two second input terminals 10 bis connected to the fourth AC voltage terminal 1 d. This connection can be effected by a suitable first changeover switch 41 and a suitable second changeover switch 42, wherein, in the case of a single-phase AC voltage, the first changeover switch 41 connects the two first input terminals 10 ato the first AC voltage terminal 1 aand the second changeover switch 42 connects the two second input terminals 10 bto the second AC voltage terminal 1 b. In the case of a three-phase alternating voltage, the first changeover switch 41 connects one of the two first input terminals 10 ato the first alternating voltage terminal 1 aand the other of the two first input terminals 10 ato the third alternating voltage terminal 1 c, while the second changeover switch 42 connects one of the two second input terminals 10 bto the second alternating voltage terminal 1 band the other of the two second input terminals 10 bto the fourth alternating voltage terminal 1 d. The first changeover switch 41 and the second changeover switch 42 can operate automatically, in particular.FIG. 4 shows a converter circuit 10 which can be used in a power supply system 1, 1', 1" according to an embodiment of the invention. In particular, this power converter circuit 10 can be used in the power supply system 1 shown in FIG. 1.For this purpose, the converter circuit 10, 10' has a first drivable semiconductor switching element 12a and a second drivable semiconductor switching element 12b, both of which are connected to the first input terminal 10a. The first drivable semiconductor switching element 12 ais furthermore connected to the first output terminal 11 a, while the second drivable semiconductor switching element 12 bis connected to the second output terminal 11 b. In addition, the power conversion circuit 10 includes a third drivable semiconductor switching element 13 aand a fourth drivable semiconductor switching element 13 b. Here, the third drivable semiconductor switching element 13 ais connected to the second input terminal 10 band the first output terminal 11 a, and the fourth third drivable semiconductor switching element 13 bis connected to the second input terminal 10 band the second output terminal 11 b.By the balanced converter circuit 10 thus set forth, when an AC voltage is applied between the first input terminal 10 aand the second input terminal 10 b, first and second DC voltages can be generated.The interconnection of the connections of the converter circuit 10, 10' illustrated in FIG. 4 could also be used in the converter arrangement 1000' of FIG. 2 or 3. For this purpose, a first and second or third and fourth drivable semiconductor switching element 12 a, 12 b, 13 a, 13 b, respectively, would be used for each of the first input connections 10 aand each of the second input connections 10 b. Furthermore, the central output connection 11 c,or it would not be connected to any of the input connections 10 a, 10 b,would be dispensed with in this case.FIG. 5 shows a converter circuit 10'' which can be used in a power supply system 1, 1', 1" according to a further embodiment of the invention.In contrast to the converter circuit 10 as shown in FIG. 4, the converter circuit 10'' further comprises a central output terminal 11 c, via which the converter circuit 10'' can be connected to the central terminal 30 arranged between the first capacitor 31 and the second capacitor 32.In addition to the first to fourth drivable semiconductor switching elements 12a, 12b, 13a, 13b, the converter circuit 10'' has a fifth drivable semiconductor switching element 12c and a sixth drivable semiconductor switching element 12d. The fifth and sixth drivable semiconductor switching elements 12 c, 12 dare connected in series between the first input terminal 10 aand the central output terminal 11 c. Furthermore, the converter circuit 10'' comprises a seventh drivable semiconductor switching element 13c and an eighth drivable semiconductor switching element 13d, which in turn are connected in series between the second input terminal 10b and the central output terminal 11c. The fifth and sixth drivable semiconductor switching elements 12 c, 12 dand the seventh and eighth drivable semiconductor switching elements 13 c, 13 dare connected in series in such a way that no current can flow unintentionally between the first input terminal 10 aor the second input terminal 10 band the central output terminal 11 c. That is to say that if the drivable semiconductor switching elements are MOSFETs, for example, the current flow through a single drivable semiconductor switching element would be able to be blocked only in one direction, since the body diode of the MOSFET is conductive in the other direction. By arranging two drivable semiconductor switching elements in series, a current flow can be prevented by connecting the drivable semiconductor switching elements in such a way that the directions in which the body diodes can conduct the current are opposite to one another (so-called back-to-back circuit). A corresponding functionality can likewise be represented with individual bidirectionally blocking switching elements, for example GaN switching elements. Accordingly, the fifth and sixth drivable semiconductor switching elements 12 c, 12 dor the seventh and eighth drivable semiconductor switching elements 13 c, 13 dmay be replaced by a bidirectional switching element, respectively.The converter circuit 10'' could be used in the power supply system 1 shown in FIG. 1, for example. For this purpose, the power converter circuit 10 shown in FIG. 1 would have to have only one central output terminal 10 c, which can be connected to the central terminal 30.If the converter circuit 10'' is to be installed in the power supply system 1', 1'' of FIG. 2 or 3, the circuit shown would have to be inserted once for a pair of first input terminal 10a and second input terminal 10b. In this case, this would mean that the converter circuit 10'' shown would be present twice.

Claims

Power supply system (1, 1', 1") for an electric vehicle, comprising: - a first AC voltage connection (1a) and a second AC voltage connection (1b) which are configured to be connected to an AC voltage source, and - a converter arrangement (1000), the converter arrangement (1000) comprising: - a balanced converter circuit (10, 10', 10") with power factor correction, wherein the converter circuit (10, 10', 10") is connected via at least one first input connection (10a) to the first AC voltage connection (1a) and via at least one second input connection (10b) to the second AC voltage connection (1b) and is configured to convert the AC voltage present between the first AC voltage connection (1a) and the second AC voltage connection (1b) into a first DC voltage (U2a), which is present between a first output terminal (11a) of the converter circuit (10) and a central terminal (30), and to convert a second DC voltage (U2b) which is present between a second output terminal (11b) of the converter circuit (10, 10', 10") and the central terminal (30), - a first capacitor (31) which is connected between the first output terminal (11a) and the central terminal (30), and - a second capacitor (32) which is connected between the second output terminal (10b) and the central terminal (30), wherein the power supply system (1, 1', 1") is configured to generate a load (50) which is connected between the first AC voltage terminal (1a) and the central terminal (30) during a charging process in which the power supply system (1, 1', 1") to supply a predetermined alternating voltage to the external alternating voltage source.The power supply system (1') according to claim 1, wherein the converter circuit (10') comprises: - a plurality of first input terminals (10a), each of the plurality of first input terminals (10a) being connected to the first AC voltage terminal (1a), respectively, and - a plurality of second input terminals (10b), each of the plurality of second input terminals (10b) being connected to the second AC voltage terminal (1b), respectively.The power supply system (1") according to claim 1 or 2, wherein the power supply system (1") further comprises: - a third AC terminal (1c) and a fourth AC terminal (1d) adapted to be connected to an AC voltage source, wherein the converter circuit (10') comprises two first input terminals (10a) and two second input terminals (10b), and wherein the converter arrangement (1000') further comprises: - a first changeover switch (41) arranged between the two first input terminals (10a), the first AC voltage terminal (1a) and the third AC voltage terminal (1c) and adapted to, when the power supply system (1") is connected to a two-phase external AC voltage source, connect the two first input terminals (10a) to the first AC voltage terminal (1a), and, when the power supply system (1") is connected to a three-phase external AC voltage source, one of the two first input terminals (10a) is connected to the first AC voltage terminal (1a) and the other of the two first input terminals (10a) is connected to the third AC voltage terminal (1c), and a second changeover switch (42), which is arranged between the two second input terminals (10b), the second AC voltage terminal (1b) and the fourth AC voltage terminal (1d) and is configured, when the power supply system (1") is connected to a two-phase external AC voltage source, to connect the two second input terminals (10b) to the second AC voltage terminal (1b) and, when the power supply system (1") is connected to a three-phase external AC voltage source, connecting one of the two second input terminals (10b) to the second AC voltage terminal (1b) and connecting the other of the two second input terminals (10b) to the fourth AC voltage terminal (1d).Power supply system (1, 1', 1") according to one of the preceding claims, wherein the converter arrangement (1000, 1000') further comprises: - at least first inductance (21), which is respectively arranged between one of the at least one first input terminal (10a) of the converter circuit (10') and the AC voltage terminal (1a, 1c) to which the respective first input terminal (10a) is connected, and - at least one second inductance (22), which is respectively arranged between one of the at least one second input terminal (10b) of the converter circuit (10') and the AC voltage terminal (1b, 1d) to which the respective second input terminal (10b) is connected.Power supply system (1, 1', 1") according to one of the preceding claims, wherein the converter circuit (10, 10', 10") further comprises: - at least one first drivable semiconductor switching element (12a) arranged between one of the at least one first input terminal (10a) and the first output terminal (11a), - at least one second drivable semiconductor switching element (12b) arranged between the same of the at least one first input terminal (10a) and the second output terminal (11b), - at least one third drivable semiconductor switching element (13a) arranged between one of the at least one second input terminal (10b) and the first output terminal (11a), and - at least one fourth drivable semiconductor switching element (13b) arranged between the same of the at least one second input terminal (10b) and the second output terminal (11b).Power supply system (1, 1', 1") according to the preceding claim, wherein the converter circuit (10', 10") further comprises: - a central output terminal (11c) connected to the central terminal (30), - a fifth drivable semiconductor switching element (12c) and a sixth drivable semiconductor switching element (12d) connected in series between one of the at least one first input terminal (11a) and the central terminal (10c), and / or - a seventh drivable semiconductor switching element (13c) and an eighth drivable semiconductor switching element (13d) connected in series between one of the at least one second input terminal (11b) and the central terminal (10c).A vehicle comprising a charging port adapted to connect the vehicle to an external alternating voltage source and a power supply system (1, 1', 1") according to any of the preceding claims, wherein each of the alternating voltage ports (1a, 1b, 1c, 1d) of the power supply system (1, 1', 1") is connected to corresponding ports of the charging port.A method of operating a power supply system (1, 1', 1") according to any one of claims 1 to 6, the method comprising: controlling (S100) the voltage level of the center terminal (30) so that a predetermined alternating voltage is applied to the load (50).Method according to the preceding claim, wherein the voltage level of the central connection (30) is controlled by modulation of the alternating voltage present at the first alternating voltage connection (1a) and / or of the alternating voltage present at the second alternating voltage connection (1b).Computing unit which is configured to carry out all method steps of a method according to one of Claims 8 or 9.A computer program which causes a computing unit to perform all method steps of a method according to one of claims 8 or 9 when it is executed on the computing unit.A machine-readable storage medium having stored thereon a computer program according to the preceding claim.

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