Converter unit of a vehicle electrical system and vehicle electrical system with converter unit

Abstract

Converter unit (WE) of a vehicle electrical system, wherein the converter unit has a first interface (LS) configured as a charging interface (LS), wherein the charging interface (LS) of the converter unit (WE) is configured to be connected to a charging port of the vehicle electrical system intended for connection to external power sources, and wherein the converter unit has a second interface (SS2), wherein the converter unit (WE) has several DC-DC converters (W1, W2), a configuration circuit (KS), and selection switches (AS1, AS2), wherein the converters (W1, W2) are connected to the selection switches (AS1, AS2) via the configuration circuit (KS), the charging interface (LS) is connected to the configuration circuit (KS) via the converters (W1, W2), and the configuration circuit (KS) is connected to the second interface (SS2) via the selection switches (AS1, AS2), wherein the converters (W1, W2) each have a first side (S1, S1').which is connected to the charging interface (LS), and have a second side (S2, S2') which is connected to the configuration circuit (KS), wherein the configuration circuit (KS) has a first switching state (1) in which the configuration circuit (KS) connects the second sides (S2, S2') in parallel and connects them to the selection switches (AS1, AS2), and the configuration circuit (KS) has a second switching state (2) in which the configuration circuit (KS) connects the second sides (S2, S2') in series and connects them to the selection switches (AS1, AS2), wherein components to be supplied are connected to the second interface (SS2), such that the second sides (S2, S2') of the multiple converters (W1, W2) are connected to the configuration circuit (KS), which is set up by controlled parallel or series configuration of these converters (W1, W2),to generate different nominal voltages for the component to be supplied for different purposes, wherein the selection switches (AS1, AS2) are designed to select different component groups for connection to the converters (W1, W2) in different configurations of the configuration circuit (KS).

Description

[0001] Vehicles with electric drive systems have, in addition to the electric drive unit, other electrical components that require power. Drive components, especially the electric motor and the battery, have high power requirements, which is why they are operated at high nominal voltages. Furthermore, the nominal voltage of the battery can differ from that of the electric motor, particularly to enable very high nominal voltages for fast-charging systems. If the nominal voltages of different branches of the vehicle's electrical system differ, multiple nominal supply voltages must be provided. Therefore, a separate converter is typically used for each of the different nominal voltages, with a specific turns ratio that matches the required nominal voltage.

[0002] The pre-published document DE 10 2018 217 238 A1 describes a charging circuit with a DC voltage input, a configuration circuit, and two intermediate circuit capacitors of corresponding converters following the configuration circuit. The converters are connected in parallel on the side facing away from the configuration circuit, with a DC voltage output directly connected to this parallel connection.

[0003] German patent application DE 10 2016 123 924 A1 describes a charging circuit with two charging strings, each equipped with a rectifier and a downstream DC-DC converter. On the output side, the DC-DC converters of the different charging strings can be connected in parallel or series and, configured in this way, directly connected to the single output of this charging circuit.

[0004] The publication DE 696 25 119 T2 shows an in-vehicle alternator with a circuit that is rigidly connected downstream of it and directly powered by it. No provision is made for supplying electrical energy from an external source.

[0005] One of the aims of the invention is to demonstrate a way in which vehicle electrical systems with different nominal voltages can be implemented cost-effectively.

[0006] This problem is solved by the subject matter of the independent claims. Further properties, features, embodiments and advantages become apparent with the dependent claims as well as with the description and the figures.

[0007] It is proposed to use multiple converters, which are connected on the side where the components to be powered are connected to a configuration circuit. This circuit, through controlled parallel or series connection (or configuration) of the converters, can generate different nominal voltages for various purposes on the component side. In a series configuration, the output voltages of the converters are added together, while this is not the case in a parallel configuration. This allows for the generation of different supply voltages. Furthermore, selector switches are provided, which allow different component groups to be selected for connection to the converters depending on the configuration.In this way, a first group of components can be selected that has a particularly high nominal voltage, which is connected to the converters in a series configuration, while in the same way a second group of components with a lower nominal voltage can be selected and connected to the converters in order to connect appropriately configured converter outputs (in parallel configuration) to these components.

[0008] A converter unit for a vehicle electrical system is therefore proposed, wherein the converter unit has a first interface and a second interface. The first interface is designed as a charging interface, i.e., as the charging interface of the converter unit, which can be connected, for example, to a charging socket (outside the converter unit). The converter unit further has a second interface, which in particular has several connections that can be selected via selector switches. The second interface is thus a multi-connection interface and serves, for example, for connection to an electric motor and / or to a battery and / or to electrical power components such as heating elements of an exhaust gas purification system or an air conditioning system, or even electrically driven air conditioning compressors.

[0009] The multiple DC-DC converters of the converter unit can, for example, be two DC-DC converters. The DC-DC converters of the converter unit are preferably identical in design. In particular, the DC-DC converters have the same transformation ratios, the same maximum current, the same rated power, and the same rated voltages.

[0010] The converter unit is further equipped with a configuration circuit and selection switches. As mentioned, the configuration circuit allows for the parallel or series configuration (controllable) of one side of the multiple converters. The selection switches allow a second interface to select a group of components from several to connect to the converters via the configuration circuit. The converters are connected to the selection switches via the configuration circuit. The charging interface, i.e., generally the first interface, is connected to the configuration circuit via the converters. The configuration circuit is connected to the second interface via the selection switches. Thus, the first interface, i.e., the charging interface, is connected to the second interface via the converters, the configuration circuit, and the selection switches, specifically in the order mentioned.Each converter has a first side and a second side. The first side is used to connect a charging source, generally a charging station, which can also be capable of regenerative charging. The second side is used to connect the component or group of components selected (using the selector switches). As mentioned, the configuration circuit located between the converters (or their second side) and the selector switches allows for the configuration, i.e., the targeted, configured connection of the second sides of the converters. The second side of the converters is connected to the configuration circuit.

[0011] The configuration circuit has a first switching state in which it connects the second sides of the converters in parallel. The resulting parallel connection of the second sides of the converters is connected by the configuration circuit to the selector switches; the configuration circuit is set up and wired for this purpose. The configuration circuit has a second switching state in which it connects the second sides in series. The resulting series connection of the second sides of the converters is connected by the configuration circuit to the selector switches, particularly in the second switching state of the configuration circuit. The first sides of the converters can be referred to as input sides, while the second sides can be referred to as output sides. This relates specifically to the direction of energy flow during charging.When feeding back, other suitable terms arise (namely first side: output side and second side: input side), so that the terms first and second side are used here and not the terms intended for specific applications such as input side and output side.

[0012] The selector switches can be electromechanical. In particular, they are designed as changeover switches. Each selector switch has a center contact and at least two selectable contacts that can be selectively connected to the center contact. The connections of the second interface can be selected using these selectable contacts. One selector switch is provided for each of the two DC voltage potentials. Thus, the selector switches can be implemented using a double-pole changeover switch (which preferably has, in addition to two switching positions in which connections are made, a third neutral position in which the center contact or center connection remains disconnected).

[0013] The converters are preferably galvanically isolated converters. They comprise a chopper, a transformer, and a subsequent rectifier. The output voltage and current can be adjusted by the duty cycle of the chopper. Preferably, the converters are controlled by the same converter controller. In particular, the converters are controlled by the same control signals. The configuration circuit can include a switching device for setting the respective switching state, in particular at least one changeover switch, a normally open contact, a normally closed contact, or the like. This can be electromechanical or designed as a semiconductor switching device.

[0014] In one embodiment, the configuration circuit includes a changeover switch. Its switching position is set according to the switching state of the configuration circuit. In other words, the switching state of the configuration circuit corresponds to the switching state of the changeover switch (generally: the switching device), whereby the changeover switch (generally: the switching device) thus executes the switching states of the configuration circuit. Via the changeover switch, in the first switching state of the configuration circuit, a first terminal potential of the second side of the first converter is connected to a first terminal potential of the second side of the second converter. Thus, the same potentials (i.e., positive or negative) of the converters are connected to each other via the changeover switch in the first switching state of the configuration circuit.As mentioned, the switching position of the changeover switch changes with the switching state of the configuration circuit, since these are identical in this embodiment. In the second switching state of the configuration circuit, the first terminal potential of the second side of the first converter is connected to a second terminal potential of the second side of the second converter via the changeover switch. Thus, in the second switching state of the configuration circuit, the changeover switch connects one of two potentials (positive or negative) of the second side of the first converter to another (i.e., negative or positive) potential of the second side of the second converter. In this latter case, a series connection results. The series connection is established by the changeover switch in the first switching state of the configuration circuit, whereby the converters are connected in series (and thus different potentials of different converters are connected to each other).In the first switching state of the configuration circuit, the switch connects the different converters with the same or similar potential (plus or minus).

[0015] It may be provided that, particularly in this embodiment, the configuration circuit includes a diode. This diode can connect the second terminal potential of the second side of the second converter to the second terminal potential of the second side of the first converter. Thus, the diode connects two identical potentials (i.e., positive or negative) of the second side of different converters. The reverse bias points away from the second terminal potential of the second side of the first converter. In particular, it points towards the second terminal potential of the second side of the second converter.

[0016] There are preferably two potentials on the selector switch side, namely positive and negative. One of the converters, in particular the first converter, is connected to one of these potentials, specifically to the higher of the two. The second converter, or a further converter, is connected to the other potential on the selector switch side. The potentials on the selector switch side are connected to the selector switches, in particular to their center contact or center terminal. If a diode is provided, it is directly connected to one of the potentials on the selector switch side. The connection is such that the diode is reverse-biased with respect to this potential.

[0017] If the converter unit includes a switch and a diode, the diode can, for example, start at the positive potential of the second side of the second converter and connect to the positive potential on the selector switch side. In this case, the diode is directly connected to the positive terminal of the second side of the first converter. Alternatively, when using a switch with a diode in the configuration circuit, the diode can be directly connected to the smaller (i.e., negative) potential of the two selector switch potentials. The other end of the diode is directly connected to the negative potential of the second side of the first converter. Thus, in this case, the diode connects the negative terminal of the second side of the first converter to the negative terminal of the second side of the second converter.In one embodiment, the forward direction leads from the negative potential of the selector switch-side potentials to the negative potential of the first transducer. In this case, the changeover switch is connected via its center terminal to the positive potential of the second side of the second transducer and selectively connects this to either the positive or the negative potential of the second side of the first transducer.

[0018] Another embodiment provides that the configuration circuit has two diodes and, in particular, no changeover switch whose switching position would change with the switching state of the configuration circuit, but only a switch that is open or closed depending on the switching state of the configuration circuit.

[0019] In this embodiment, the configuration circuit comprises two diodes. The configuration circuit includes a first diode that connects the first terminal potential of the second side of the first converter to the first terminal potential of the second side of the second converter. Furthermore, the configuration circuit includes a second diode that connects the second terminal potential of the second side of the first converter to the second terminal potential of the second side of the second converter. The reverse bias of the first diode points away from the first terminal potential of the second side of the first converter. The forward bias of the second diode points away from the second terminal potential of the second side of the second converter. The first terminal potential (of each converter) can be a negative potential. The second terminal potential (of each converter) can be a positive potential.The first diode can point away from the negative potential of the second side of the second converter and lead to the negative potential of the second side of the first converter. Similarly, the second diode can point from the positive potential of the second side of the second converter to the positive potential of the second side of the first converter, which is the forward direction. Thus, the first and second diodes each connect a potential of the second side of the first converter (positive or negative) to the corresponding potential of the second side of the second converter. In this configuration, the diodes connect the same potentials of different converters. The first diode connects the negative potentials of the second sides of the two converters, and the second diode connects the positive potentials of the second sides of the two converters. The forward direction (of the diodes) leads away from the second converter and towards the first converter.

[0020] To enable configuration, the configuration circuit includes a switch (e.g., a normally open or a normally closed switch). The switch is specifically single-pole. The switch connects the first terminal potential of the second side of the first converter to the second terminal potential of the second side of the first converter and to the second terminal potential of the second side of the second converter. In the first switching state of the configuration circuit, the switch is open, and in the second switching state, the switch is closed. The switch thus connects those terminals or potentials of the second side of the converters to which the diodes are connected. In other words, the switch connects the potentials of the second sides of the converters that are not connected to one of the selection switches.These are in particular the “inner” terminals of the converters (to which the diodes and the switch are connected), whereas the “outer” terminals of the converters are connected to the selection switches and thus represent the supply potentials (+, -) of the converter unit.

[0021] The charging interface is an interface of the converter unit and thus a component used to connect the converter unit to other components (of the vehicle's electrical system). The charging interface of the converter unit is preferably configured to be connected to a charging port of the vehicle's electrical system, which is intended for connection to external power sources. The charging port (e.g., a charging socket) of the vehicle's electrical system can therefore be designed according to a standard for wired charging of plug-in vehicles. Additional components such as rectifiers or similar devices can be provided between the interface of the converter unit and the charging port of the vehicle's electrical system (which forms an external interface).

[0022] The charging interface of the converter unit is designed to be connected to the charging port of the vehicle's electrical system. The charging port, for which the converter unit's charging interface is designed, can belong to a first branch of the electrical system. The second interface can also be designed for connection to components of the vehicle's electrical system, in particular to multiple branches. In this case, the first connection of the second interface is designed for connection to a second branch of the electrical system. The second connection of the second interface is designed for connection to a third branch of the electrical system. The second interface thus comprises two different connections (each with two potentials). The second branch of the electrical system and the charging port have different nominal voltages. In particular, the connections of the second interface are designed for different nominal voltages.

[0023] Furthermore, a control unit can be provided that is connected to the configuration circuit. This control unit (which belongs to the converter unit) is preferably also connected to the selection switches. The control unit is preferably configured to control the configuration circuit in a parallel state, connecting the second sides in parallel. Furthermore, the control unit is preferably configured to control the selection switches in a first position in the parallel state. In this position, the configuration circuit is connected to the first terminal of the second interface. In the parallel state, the selection switches connect the configuration circuit to the first terminal of the second interface. The control unit can also be configured to control the configuration circuit in a serial state, connecting the second sides of the converters serially.In serial mode, the controller is further configured to actuate the selector switches in a second position. In this second position, the selector switches connect the configuration switches to a second terminal of the second interface. Depending on the state, the selector switches connect the configuration circuit to different terminals of the second interface. In serial mode, the selector switches connect the configuration circuit to the second terminal, and in parallel mode, they connect it to the first terminal. The configuration circuit also assumes two different switching positions depending on the state (parallel or serial).

[0024] The control system is preferably configured to first establish a neutral state when setting a parallel or serial state. In the neutral state, the selector switches do not connect the configuration circuit to any of the terminals of the second interface. Rather, the neutral position is an empty position in which the selector switches are disconnected. In this case, the center terminals of the selector switches are not connected to any contact that would be connected to other components, or the selector switches themselves are not connected to any contact when they are in the neutral state. The neutral state is considered, in particular, to be the state of the converter unit or the control system. After this state has been established, a parallel or serial state is preferably set (especially according to a specification from a higher-level control system).This parallel or series state is set after the neutral state on the configuration circuit. After setting the parallel or series state of the configuration circuit, the selector switches are moved to a first or second position, specifically to a position where the selector switches (unlike the neutral state) connect the configuration circuit to a terminal of the second interface.

[0025] First, the system determines whether a switching command is present, requiring a switching state to be set. If so, a neutral state is initially set (by the controller), in which the selector switches are in a neutral position. The configuration circuit is then switched to a parallel or series state (according to the predefined setting). Only after this process is complete do the selector switches move to the first or second position, i.e., leave the neutral state. This prevents components connected to the second interface from receiving an unsuitable voltage, particularly an overvoltage.Once the correct state (serial or parallel state) of the configuration circuit is set, the selection switches are in a neutral state and only move to a state in which a connection is made to a terminal of the second interface after the setting has been completed.

[0026] The converter unit can be integrated into a vehicle electrical system. A vehicle electrical system can therefore be provided that includes a converter unit as described herein. The vehicle electrical system further comprises a first, second, and third branch. The first branch has a charging port, in particular the aforementioned charging port of the branch, which is connected to the converter unit. The charging port of the branch is configured for connection to external power sources, preferably designed according to a standard for wired charging of plug-in vehicles. The second branch has a different nominal voltage than the third branch. The second branch has at least one electrical component with a first nominal voltage, and the second branch has at least one electrical component with a second nominal voltage.The second rated voltage is different from the first rated voltage. In particular, the second rated voltage is higher, and preferably twice as high, as the first rated voltage. Thus, the selector switches connect the third branch of the electrical system to the converters when the configuration circuit is in series, resulting in a high voltage (namely, twice the voltage with two converters). The selector switches connect the configuration circuit to the second branch of the electrical system when the configuration circuit is in parallel, resulting in a lower voltage, namely half the voltage provided in series.

[0027] The second branch of the electrical system can include at least one electrical component, such as a heating element or an electric air conditioning compressor. These components operate at the first nominal voltage. The third branch of the electrical system can include at least one electrical component, such as a traction battery, a heating element, an electric air conditioning compressor, or a combination thereof, all of which operate at the second nominal voltage.

[0028] The Fig. 1 and Fig. Figure 2 serves to illustrate exemplary embodiments of the converter unit and the vehicle electrical system described here.

[0029] The Fig. Figure 1 shows a converter unit WE with a first interface, which serves as the charging port of the converter unit. The converter unit further includes a second interface SS2, which has two terminals A1 and A2. Each of these terminals has two potentials, i.e., two potential contacts.

[0030] The converter unit comprises several DC-DC converters; in the case of the Fig. 1. Two units in the form of a first converter W1 and a second converter W2. Each of these converters has a first side S1, S1' and a second side S2, S2'. The first sides S1, S1' of converters W1, W2 are on the side of the charging port LS of converter unit WE, while the second sides S2, S2' are opposite converters W1, W2. The second sides S1, S2 face the second interface.

[0031] The converter unit also includes a configuration circuit KS. Depending on the switching state, this circuit is configured to connect the second terminals S2 and S2' of converters W1 and W2 in parallel or series. Selector switches AS1 and AS2 are connected to the second terminals S2 of converters W1 and W2 via the configuration circuit KS. These selector switches AS1 and AS2 allow for the adjustable selection of which of the two terminals A1 and A2 is to be connected to the configuration circuit KS. A controller ST controls both a changeover switch U, which is used in the configuration circuit to set the switching state, and the selector switches AS1 and AS2.

[0032] In the Fig. Figure 1 shows an embodiment in which the first transducer has a first terminal potential WA1- and a second terminal potential WA1+ on its second side S2. The first terminal potential WA1- is the negative potential of the second side S2 of transducer W1, and the terminal potential WA1+ is the positive potential of the second side S2 of the first transducer W1. Similarly, the second transducer W2 has a first terminal potential WA2- (negative potential) and a positive potential WA2+ (positive potential) on its second side S2'. The two outer potentials WA1+ and WA2- of the two transducers W1 and W2 are each connected to a center terminal of the selector switches AS1 and AS2, respectively. The first selector switch AS1 is thus connected to the positive potential, and the second selector switch AS2 to the negative potential of the transducer unit WE.

[0033] The internal terminal potentials WA1- and WA2+ of converters W1 and W2 can be connected to each other in different ways via the configuration circuit. The first terminal potential, WA1-, is connected to the center terminal of the switch U, so that this potential WA1- can be selected to be connected either to the first potential WA2- of the other converter (W2) or to the second potential WA2+ of the second converter. In switching state 1 of the switch U, the negative terminal potential WA1- (i.e., the first terminal potential WA1-) of the first converter W1 is connected to the negative potential of the converter unit, i.e., to the first terminal potential WA2- of the second converter W2. In the second switching state 2, the switch U connects the first terminal potential WA1- to the second terminal potential WA2+ of the second converter W2. A diode D connects the second terminal potential WA2+ of the second converter W2 to the positive potential of the converter unit WE.with the second potential WA1+ of the first converter W1. Here, the forward bias of diode D leads to the first converter W1. The potentials of the converter unit can also be referred to as busbars. In the . Fig. 1. Two busbars are provided, namely a positive and a negative busbar. These busbars run from the converters to the selection switches AS1 and AS2.

[0034] A controller ST is connected to the changeover switch U and the selector switches AS1 and AS2. In the first switching state 1 of the changeover switch U, and thus of the configuration circuit KS, the terminal potentials WA1+, WA1-, WA2+, and WA2- of the converters W1 and W2 are connected in parallel. In the second switching state 2 of the changeover switch, and thus in the second switching state of the configuration circuit, the terminal potentials of the two converters W1 and W2 are connected in series. Specifically, the connection of WA1- with WA2+ results in the outer terminal potentials WA1+ and WA2- carrying the sum of the voltages on the second side S2 of the converters W1 and W2. The selector switches AS1 and AS2 have a different switching position in the first switching state (i.e., in the parallel state) than in the series state (i.e.,In the second switching state 2, the selection switches connect the configuration circuit to different terminals (A1+ or A2+,-) depending on the switching state. This allows two different on-board power supply branches BZ2 and 3 to be connected to terminals A1 and A2, and it is possible for the on-board power supply branches B2 and 3 to have different nominal voltages. On-board power supply branch BZ1 is used to connect the converter unit, for example, to an external charging station and can have a standardized charging plug or socket.

[0035] The ST control unit is configured to switch the changeover switch U and the selection switches AS1, AS2, in particular according to a switching command from a higher-level control unit (not shown).

[0036] The selector switches AS1 and AS2 can have a third position, namely a neutral position, in which they do not connect the configuration circuit KS to either terminal A1 or A2. It can be provided that when the switching position of the changeover switch U or the configuration circuit KS changes, the controller sets the selector switches AS to the neutral position. Preferably, before the changeover switch U is switched, the controller sets the selector switches AS1 and AS2 to a neutral position, and only after the changeover switch U has been switched does it assume one of the two selected switching positions in which the selector switches connect the configuration circuit KS to one of the terminals A1 or A2.

[0037] The Fig. Figure 2 shows a similar circuit, in which, in particular, the switches, the control unit, the connections A1, A2, the converters and the charging interface are set up and connected as in the Fig. 1 shown. Fig. 2 differs in particular from the configuration circuit KS of the Fig. 1.

[0038] The following section refers to the configuration circuit KS of the Fig. 2. Reference is made. This includes an opener or a closer VS, and in this Fig. 1. No switch. Furthermore, two diodes D1 and D2 are present in the configuration circuit KS of the Fig. 2. The switch VS selectively connects the internal potentials of the converters W1 and W2, i.e., the potential terminals WA1- and WA2+, in a switchable manner. As also in the Fig. 1. The outer potential terminals WA1+ and WA2- are permanently connected to the potential of the converter unit WE. The first diode D1 connects the first potential (the negative potential) of the converter unit WE to the first terminal WA1- of the second side S2 of the first converter W1. The forward direction here leads from the first potential of the converter unit WE to the first converter W1. The second diode D2 connects the second terminal potential WA2+ to the second potential of the converter unit (i.e., to the positive terminal or the positive busbar). The forward direction here points towards the first converter. The switch VS, like the changeover switch U, Fig. 1. Two switching positions, namely 1 and 2: In the first switching position 1, the configuration circuit KS connects converters W1 and W2 in parallel, while in the second switching position, the configuration circuit KS connects converters W1 and W2 (their second sides) in series. This is similar to the control ST with the changeover switch U in the... Fig. If the ST controller is connected to switch VS (also called the connecting switch) via control input 1, then the ST controller is also connected to the VS switch (also called the connecting switch). The same applies to setting the switching positions via the ST controller as in the... Fig. 1 shown, where the switching positions are the same and are designated in the same way (1 and 2).

[0039] The terminals of the second interface are designated A1 and A2, where A1 is shorthand for A1+, A1- and A2 is shorthand for A2+, A2-. Thus, each terminal A1, A2 has two connection potentials (A1+, A1- and A2+, A2-).

Claims

[1] Converter unit (WE) of a vehicle electrical system, wherein the converter unit has a first interface (LS) which is designed as a charging interface (LS), wherein the charging interface (LS) of the converter unit (WE) is designed to be connected to a charging connection of the vehicle electrical system which is provided for connection to external power sources and wherein the converter unit has a second interface (SS2), wherein the converter unit (WE) has a plurality of DC-DC converters (W1, W2), a configuration circuit (KS) and selection switches (AS1, AS2), wherein the converters (W1, W2) are connected to the selection switches (AS1, AS2) via the configuration circuit (KS), the charging interface (LS) is connected to the configuration circuit (KS) via the converters (W1, W2) and the configuration circuit (KS) is connected to the second interface (SS2) via the selection switches (AS1, AS2), wherein the converters (W1, W2) each have a first side (S1, S1'),which is connected to the charging interface (LS), and a second side (S2, S2') which is connected to the configuration circuit (KS), wherein the configuration circuit (KS) has a first switching state (1) in which the configuration circuit (KS) connects the second sides (S2, S2') in parallel and connects them to the selection switches (AS1, AS2), and the configuration circuit (KS) has a second switching state (2) in which the configuration circuit (KS) connects the second sides (S2, S2') in series and connects them to the selection switches (AS1, AS2), wherein components to be supplied are connected to the second interface (SS2), so that the second sides (S2, S2') of the plurality of converters (W1, W2) are connected to the configuration circuit (KS), which is set up by controlled parallel or serial configuration of these converters (W1, W2),to generate different nominal voltages for the component to be supplied for different purposes, wherein the selection switches (AS1, AS2) are designed to select different component groups for connection to the converters (W1, W2) for different configurations of the configuration circuit (KS). [2] Converter unit (WE) according to claim 1, wherein the selection switches (AS1, 2) in a first position connect the configuration circuit (KS) to a first terminal (A1+, A1-) of the second interface, in a second position connect the configuration circuit (KS) to a second terminal (A2+, A2-) of the second interface (SS2), and in a third position disconnect the configuration circuit (KS) from the first and from the second terminal (A1+, A1-; A2+, A2-). [3] Converter unit (WE) according to claim 1 or 2, wherein the configuration circuit (KS) has a changeover switch (U) via which, in the first switching state (1) of the configuration circuit (KS), a first terminal potential (WA1-) of the second side (S2) of the first converter (W1) is connected to a first terminal potential (WA2-) of the second side (S2') of the second converter (W2), and via which, in the second switching state (2) of the configuration circuit (KS), the first terminal potential (WA1-) of the second side (S2) of the first converter (W1) is connected to a second terminal potential (WA2+) of the second side (S2') of the second converter (W2). [4] Converter unit (WE) according to claim 3, wherein the configuration circuit (KS) comprises a diode which connects the second terminal potential (WA2+) of the second side (S2') of the second converter (W2) to the second terminal potential (WA1+) of the second side (S2) of the first converter (W1) and whose blocking direction points from the second terminal potential (WA1+) of the second side (S2') of the first converter (W2) to the second terminal potential (WA2+) of the second side (S2') of the second converter (W2). [5] Converter unit (WE) according to claim 1 or 2, wherein the configuration circuit (KS) has a first diode (D1) which connects the first terminal potential (WA1-) of the second side (S2) of the first converter (W1) to the first terminal potential (WA2-) of the second side (S2') of the second converter (W2) and has a second diode (D2) which connects the second terminal potential (WA1+) of the second side (S2) of the first converter (W1) to the second terminal potential (WA2+) of the second side (S2') of the second converter (W2), wherein the reverse direction of the first diode (D1) points away from the first terminal potential (WA1-) of the second side (S2) of the first converter (W1) and the forward direction of the second diode (D2) points away from the second terminal potential (WA2+) of the second side (S2') of the second converter (W2). [6] Converter unit (WE) according to claim 5, wherein the configuration circuit (KS) has a switch (VS) which switchably connects the first terminal potential (WA1-) of the second side (S2) of the first converter (W1) to the second terminal potential (WA2+) of the second side (S2') of the second converter (W2) and which is open in the first switching state (1) of the configuration circuit (KS) and is closed in the second switching state (2) of the configuration circuit (KS). [7] Converter unit (WE) according to one of the preceding claims, wherein the charging connection belongs to a first vehicle electrical system branch (BZ1), the first connection (A1+, A1-) of the second interface (SS2) is set up for connection to a second vehicle electrical system branch (BZ2), and the second connection (A2+, A2-) of the second interface (SS2) is set up for connection to a third vehicle electrical system branch (BZ3), wherein the second vehicle electrical system branch (BZ2) and the third vehicle electrical system branch (BZ3) have different nominal voltages. [8] Converter unit (WE) according to one of the preceding claims, comprising a controller (ST) which is connected in a controlling manner to the configuration circuit (KS) and the selection switches (AS1, AS2), wherein the controller (ST) is configured to control the configuration circuit in a parallel state, to connect the second sides (S2, S2') in parallel with one another and to control the selection switches (AS1, 2) in a first position in which the configuration circuit (KS) is connected to a first terminal (A1+, A1-) of the second interface (SS2), and the controller is configured to control the configuration circuit in a serial state, to connect the second sides (S2, S2') in series with one another and to control the selection switches (AS1, 2) in a second position in which the configuration circuit (KS) is connected to a second terminal (A1+, A1-) of the second interface (SS2). [9] Converter unit (WE) according to claim 8, wherein the controller (ST) is configured to first set a neutral state when setting a parallel state or series state, in which the controller sets the selection switches to a disconnecting state, to set a parallel state or series state on the configuration circuit after setting this state, and to control the selection switches in a first or a second position after setting a parallel state or series state on the configuration circuit. [10] Vehicle electrical system with a converter unit (WE) according to one of the preceding claims, a first, second and a third electrical system branch (BZ1, 2, 3), wherein the first electrical system branch (BZ1) has the charging connection which is designed for connection to external power sources, the second electrical system branch (BZ2) has at least one electrical component with a first nominal voltage, wherein this component belongs to the components to be supplied, and the third electrical system branch (BZ3) has at least one electrical component with a second nominal voltage which differs from the first nominal voltage and is in particular greater than the nominal voltage, wherein the component of the third electrical system branch also belongs to the components to be supplied. [11] Vehicle electrical system according to claim 10, wherein the second electrical system branch (BZ2) has as at least one electrical component a heating element or an electric air conditioning compressor with the first nominal voltage and the third electrical system branch (BZ3) has as at least one electrical component a traction high-voltage accumulator, or a heating element, or an electric air conditioning compressor with the second nominal voltage.

Images