DE102017206809A1 - DC-DC converter, vehicle electrical system with a DC-DC converter - Google Patents

Abstract

Disclosed is a DC-DC converter (GW1, ...) for converting between two voltages (U1, U2), comprising: - two first power terminals (A11, A12) for connecting the DC-DC converter (GW1, ...) to a first voltage (U1 ); - two second power connections (A21, A22) for connecting the DC-DC converter (GW1, ...) to a second voltage (U2); A third power terminal (A3) for switching the DC / DC converter (GW1, ...) on / to an electrical device (LD); A first voltage conversion path (SP1, SP5, SP6) for converting between the two voltages (U1, U2) electrically connected between the first power terminals (A11, A12) on the one hand and the second power terminals (A21, A22) on the other hand; A first controllable selection switch (AS1) which comprises a first (E1), a second (E2) and a third (E3) switching terminals and is connected in series in the first voltage converter path (SP1) via the first (E1) and the second (E2) switching connection , SP5) and is electrically connected to the third power terminal (A3) via the third switching terminal (E3); A power management unit (EM) for controlling the first selection switch (AS1) configured to selectively connect at least two of each of the first (E1), second (E2) and third (E3) switching terminals to each other electrically.

Description

Technical area

The present invention relates to a DC-DC converter, in particular for an electrical system of a motor vehicle, as well as an electrical system, in particular for a motor vehicle, with a DC-DC converter.

State of the art and object of the invention

Bordnetze, especially of motor vehicles, have a variety of electrical loads, which operating voltages of different types of voltage, such. As a DC voltage, a single-phase or multi-phase AC voltage, or different voltage levels or different power requirements. To be able to supply these loads despite the different operating voltages and the different power demands (at the same time) with electrical energy, the electrical systems have three or more electrical systems branches with different vehicle electrical system voltages, in which the electrical loads of different operating voltages or power requirements are divided electrically connected.

In order to be able to shift electrical energy from another vehicle electrical system branch into this vehicle electrical system display in the event of a rapid increase in the demand for electrical power in one of the vehicle electrical system branches, the on-board electrical systems usually have two or more current / voltage converters which are connected between the electronic systems during operation of the vehicle electrical system Convert on-board network voltages of different voltage types or voltage levels of the on-board network branches.

The two or more current / voltage converters require a corresponding number of control and control electronic units and other circuit arrangements for controlling or for controlling these current / voltage converters, which leads to increased complexity and thus to increased manufacturing costs of the vehicle electrical system.

Thus, the object of the present invention is to provide a way to produce a vehicle electrical system, in particular a motor vehicle, in a simple manner and inexpensively.

Description of the invention

This object is achieved with objects of the independent claims. Advantageous embodiments are the subject of the dependent claims.

According to a first aspect of the invention, a DC-DC converter for converting between a first and a second voltage (or vehicle electrical system voltage) is provided.

The DC-DC converter comprises two first power connections for connecting the DC-DC converter to the first voltage (for example a first vehicle electrical system voltage of a first electrical system branch of a vehicle electrical system), two second electrical connections for connecting the DC-DC converter to the second voltage (for example, a second vehicle electrical system voltage of a second electrical system branch of the electrical system).

The DC-DC converter further comprises at least one third power connection for switching or connecting the DC-DC converter to at least one electrical device, for example an electrical load or an electrical energy source (for example, a third electrical system branch of the electrical system), or to an electrical connection of the at least one electrical device.

The DC-DC converter further comprises at least a first voltage converter path, which is electrically connected between the two first power terminals on the one hand and the two second power terminals on the other hand and is adapted to convert between the first and the second voltage.

Here, a "conversion between the first and the second voltage (or vehicle electrical system voltage)" means that the DC-DC converter or the at least one first voltage converter path and further voltage transformer paths to be described below are set up, the first voltage (2) applied between the two first electrical connections (FIG. or a first vehicle electrical system voltage) into the second voltage (or a second vehicle electrical system voltage) between the two second electrical connections and / or vice versa. For this purpose, the DC-DC converter or the voltage converter paths corresponding circuit components, such. B. Hall bridges with controllable switches and / or diodes, coils, capacitors, for voltage conversion.

A voltage converter path is thus an electrical circuit that includes the above-mentioned voltage conversion circuit components and is configured to convert between the first and second voltages.

The DC-DC converter further comprises at least a first controllable Selection switch (or switch, in particular power selection switch or power switch), which comprises a first, a second and a third switching terminal and via the first and the second switching terminal serially in the at least one first voltage converter path and the third switching connection to the at least one third power connection electrically connected.

Here, the half-sentence means: "... via the first and the second switching connection serially electrically connected in the at least one first voltage converter path ..." that the first and the second switching connection of the at least one first selection switch are in the at least one first voltage converter path and Part of the at least one first voltage converter path. If the first and the second switching connection are electrically connected to one another in a switching state of the at least one first controllable selection switch, then the at least one first voltage converter path is electrically conductive at least in the section between the first and the second switching connection and allows current to flow through this section. If the first and the second switching connection are electrically separated from one another in a further switching state of the at least one first controllable selection switch, the at least one first voltage converter path is electrically open and the current flow through this voltage converter path is interrupted.

The DC-DC converter further comprises a power management unit for controlling the at least one first select switch configured to selectively connect at least two of the first, second, and third switch terminals to each other or to electrically disconnect each of the three switch terminals.

The invention is based on the recognition that the drive architecture of a motor vehicle with an electric drive with an electric machine, an inverter for driving them, a (traction) battery, a DC-DC converter and a charger (one and / or three-phase) one Variety of high performance electronic components.

In addition, even in conventional vehicles known high-performance electronic components such. B. a high-voltage heating or a high-voltage air conditioning compressor.

In general, a traction DC converter (traction DCDC) is further provided, which is electrically connected between the (traction) battery and the inverter and is adapted to set the DC link voltage for the inverter regardless of the state and operating point of the (traction) battery (voltage adjustment).

According to the current state, each of the above-mentioned high-performance electronic components has its own control electronics consisting of a control unit and a line-electronic actuator including driver and sensors, which leads to a high production cost and high production costs for motor vehicles. In addition, the utilization of the drive units is low.

Based on this finding, a solution was sought in the context of this invention, with the production costs and production costs for a motor vehicle, in particular a hybrid, plug-in hybrid or electric vehicle, or for its high-voltage architecture to reduce and exploitation to increase the driving units.

Within the scope of the invention, it has been recognized that the solution consists of not using the drive units only for individual functional implementations, but with a single drive electronics having a plurality of functions, e.g. Charging, heating and voltage adjustment, implement.

For this purpose, it requires a (traction) DC-DC converter, in addition to the primary function of the DC voltage conversion in addition to the above functions such. As e.g. Charging, heating and voltage adjustment can be implemented.

It was recognized that this multi-functionality of the DC-DC converter can be realized by means of a power multiplexer principle, with a power multiplexer in turn can be accomplished easily by means of a controllable selection switch.

Based on this finding, the above-described DC-DC converter has been provided with at least one first controllable selection switch, which via the first and the second switching terminal serially in the at least one first voltage converter path of the DC-DC converter and the third switching connection to the at least one third power connection (via the at least one electrical load or source can be additionally connected to the DC-DC converter) is electrically connected. The selection switch is then activated by means of the described energy management unit.

Since the above-mentioned multifunctionality of the DC-DC converter by means of a single selector switch and a corresponding software-based modification of the power management unit, which is already present for controlling the DC-DC converter, the electrical system and thus the motor vehicle can be easily and inexpensively manufactured.

This provides a possibility to produce a vehicle electrical system, in particular a motor vehicle, in a simple and cost-effective manner.

By way of example, the energy management unit is further configured to electrically connect the first and second switching terminals of the at least one first controllable selector switch to each other for conversion between the first and second voltages, thereby enabling current to flow through the at least one first voltage converter path.

The energy management unit is further configured, for example, to electrically connect the third switching connection of the at least one first controllable selection switch to the first and / or the second switching connection in order to operate the at least one electrical device and thus to enable a current flow via the DC-DC converter to the at least one electrical device ,

The energy management unit is further configured, for example, to electrically connect the first, the second and the third power connection of the at least one first controllable selection switch to one another for the conversion between the first and the second voltage and for simultaneous operation of the at least one electrical device and thus current flows through the at least one to enable a first voltage converter path and to / from the at least one electrical device.

By way of example, the at least one first voltage converter path comprises a first half-bridge which is electrically connected between the two second electrical connections and comprises two first controllable switches, which are electrically connected in series between the two second electrical connections and via a middle connection of the first half-bridge.

The at least one first selection switch is electrically connected, for example, via the first and the second switching connection between the one of the two first electrical connections and the middle connection of the first half-bridge.

The at least one first voltage converter path further includes, for example, a first inductive component, such. B. a first coil which is electrically connected between a (in particular positivspannungsseitigen) of the two first power terminals and the center terminal of the first half-bridge and in series with the at least one first selection switch.

The at least one first selection switch is electrically connected, for example, via the first and the second switching connection between the one of the two first electrical connections and the middle connection of the first half-bridge and serially to the first inductive component.

The DC-DC converter further comprises, for example, a second voltage converter path, which is electrically connected between the two first current connections on the one hand and the two second electrical connections on the other hand and thus parallel to the at least one first voltage converter path and is set up to convert between the first and the second voltage. This second voltage converter path enables a voltage conversion between the first and the second voltage independently of the first voltage converter path or the switching state of the first selection switch in the first voltage converter path.

The second voltage converter path includes, for example, a second half-bridge, which is electrically connected between the two second current terminals and thus parallel to the first half-bridge. The second half-bridge comprises two second controllable switches, which are electrically connected to one another in series between the two second current connections via a middle connection of the second half-bridge.

The second voltage converter path further includes, for example, a second inductive component, such. B. a second coil, which is electrically connected between the one of the two first power terminals and the center terminal of the second half-bridge.

The DC-DC converter further comprises, for example, a fourth power connection for connecting the DC-DC converter to the at least one electrical device or to the one electrical connection or to a further electrical connection of the at least one electrical device.

For example, the DC-DC converter further includes a third voltage conversion path for conversion between the first and second voltages. The third Voltage converter path is also electrically connected between the two first power terminals on the one hand and the two second power terminals on the other hand, and thus parallel to the at least one first and the second voltage converter path.

The DC-DC converter further comprises, for example, a second controllable selection switch (or switch, in particular, power selection switch) comprising fourth, fifth, and sixth switching terminals and, via the fourth and fifth switching terminals, serially in the third voltage conversion path and via the sixth switching terminal is electrically connected to the fourth power connector.

The energy management unit is further configured, for example, to electrically connect at least in each case two of the fourth, the fifth and the sixth switching connection to one another or to electrically disconnect all of these three switching connections from one another.

In particular, the energy management unit is arranged to electrically connect the fourth switching connection to the fifth switching connection and thus to enable a further current flow through the second voltage converter path in addition to the current flow through the at least one first voltage converter path. Thereby, the power flow in the conversion between the first and the second voltage is increased.

In particular, the energy management unit is further configured to electrically connect the sixth switching connection to the fourth and / or the fifth switching connection to increase the operating power of the at least one electrical device and thus to conduct current via the second voltage converter path (in addition to the current flow via the at least one first voltage converter path ) to enable the at least one electrical device.

The third voltage converter path comprises, for example, a third half-bridge, which is electrically connected between the two second current connections and thus parallel to the first and the second half-bridge and comprises two third controllable switches which electrically connect to each other in series between the two second electrical connections via a middle connection of the third half-bridge are connected.

The third voltage converter path further includes, for example, a third inductive component which is electrically connected between the one of the two first electrical connections and the middle connection of the third half-bridge.

The second selection switch is electrically connected, for example, via the fourth and the fifth switching connection between the one of the two first electrical connections and the middle connection of the third half-bridge and in series with the third inductive component.

The DC-DC converter further comprises, for example, a fifth power connection for connecting the DC-DC converter to the at least one electrical device or to yet another power connection of the at least one electrical device.

The DC-DC converter further includes, for example, a fourth voltage conversion path for conversion between the first and second voltages electrically connected between the first two power terminals on the one hand and the two second power terminals on the other hand, and thus parallel to the at least one first, second and third voltage conversion paths.

The DC-DC converter further comprises, for example, a third controllable selection switch (or switch, in particular, power selection switch) comprising seventh, eighth, and ninth switching terminals, and via the seventh and eighth switching terminals serially in the fourth voltage conversion path and via the ninth switching terminal is electrically connected to the fifth power connector.

The energy management unit is further configured, for example, to selectively connect at least in each case two of the seventh, the eighth and the ninth switching connection to one another electrically or to electrically disconnect all of these three switching connections from one another.

In particular, the power management unit is configured to electrically connect the seventh switching port to the eighth switching port and thus to enable the flow of current through the fourth voltage path. This further increases the power flow during conversion between the first and second voltages.

In particular, the energy management unit is further configured to electrically connect the ninth switching connection to the seventh and / or the eighth switching connection for further increasing the operating performance of the at least one electrical device and thus to conduct current via the fourth voltage converter path (in addition to the current flow via the at least one first) and the third voltage conversion path) to the to allow at least one electrical device.

The fourth voltage converter path comprises, for example, a fourth half-bridge, which is electrically connected between the two second current terminals and thus parallel to the first, the second and the third half-bridge. The fourth half-bridge comprises two fourth controllable switches, which are electrically connected to one another in series between the two second current connections via a middle connection of the fourth half-bridge.

The fourth voltage converter path further includes, for example, a fourth inductive component, which is electrically connected between the one of the two first electrical connections and the middle connection of the fourth half-bridge.

The third selection switch is electrically connected, for example, via the seventh and the eighth switching connection between the one of the two first electrical connections and the middle connection of the fourth half-bridge and in series with the fourth inductive component.

The at least one first voltage converter path further comprises, for example, an H-switching bridge, which is electrically connected between the two first electrical connections and comprises a bridge branch.

Here, the H-switching bridge is formed for example as a full bridge with four independently controllable switches, which are each connected in pairs in one of two half-bridges of the H-switching bridge via a respective middle port in series. The bridge branch connects the center connections of the two half bridges of the H-switching bridge to each other electrically.

The at least one first selection switch is connected in series electrically, for example, via the first and the second switching connection in the bridge branch of the H switching bridge.

The energy management unit is further configured, for example, to switch the H-switching bridge or its four switches in a controlled manner for conversion between the first and the second voltage.

The at least one first voltage converter path further includes, for example, a transformer having a primary coil and a secondary coil. In this case, the primary coil is electrically connected, for example, in the bridge branch of the H-switching bridge and in series with the at least one first selection switch (or serially to the current path between the first and the second switching connection of the at least one first selection switch). The secondary coil is electrically connected, for example, between the two second power terminals.

The selector switches described above and further to be described below each comprise, for example, one or more electromechanical switches and / or one or more semiconductor switches, such as, for example, one or more semiconductor switches. As MOSFET, IGBT, etc., which are electrically connected in a manner known in the art between the corresponding switching terminals of the respective selector switch, so that they can perform the above-described functions of the respective selector switch.

The selection switches can be placed either on the side of the first power connections of the respective voltage converter paths or between the inductive component and the half-bridge of the respective voltage converter paths. The placement of the selector switches can be made independently for each voltage transformer path. Ie. the first voltage converter path with the first selector switch on the side of the first power terminals and the third voltage converter path with the second selector switch between the inductive component and the half-bridge.

According to a further aspect of the invention, a vehicle electrical system, in particular for a motor vehicle, is provided.

The electrical system includes a first electrical system branch with a first (electrical system) voltage, a second electrical system branch with a second (electrical system) voltage, and a third electrical system branch with at least one electrical device, which includes, for example, an electrical load and / or an electrical energy source.

The electrical system further comprises a DC converter described above for converting between the first and the second (electrical) voltage, which via the two first power connections to the first electrical system branch and thus to the first (electrical system) voltage, via the two second power connections to the second electrical system branch and thus at the second (electrical system) voltage, and is electrically connected via the at least one third power connection to the third electrical system branch and thus to the at least one electrical device.

For example, the DC-DC converter is galvanically isolated from the third electrical system branch or the at least one electrical device, for example by means of a transformer.

The at least one electrical device includes, for example, a DC load, such as a DC heater; a single- or multi-phase AC consumer, such as a single- or multi-phase AC heater or an electric motor; a DC or AC charging port; a DC power source, such as a battery; and / or a single- or multi-phase AC power source, such as a generator.

Advantageous embodiments of the DC-DC converter described above are, as far as applicable to the above-mentioned electrical system, also to be regarded as advantageous embodiments of the electrical system.

The energy management unit is further configured, for example, to synchronize the previously described selection switches and further selector switches to be described below and semiconductor switches of the previously described and subsequently described half-bridge or H-bridge on the side of the three electrical systems so that the previously described functions such as the inductive charging or the parallel operation can be realized. Furthermore, should also parallel feeds to other electrical system branches, such. B. on a 48V Bordnetzzweig be possible.

The energy flow between the above-mentioned on-board network branches is unidirectional or bidirectional. The control of the uni- or bidirectional energy flow takes place by synchronized switching of the selector switch and the semiconductor switch of the half-bridges or the H-bridge but also by targeted permanent switching corresponding selection switch or corresponding semiconductor switch, such. B. in the case of a discharge of an energy storage in a vehicle electrical system branch (high-voltage vehicle electrical system branch).

Brief description of the drawing:

In the following, exemplary embodiments of the invention will be explained in more detail with reference to the accompanying drawings. Showing:

1 in a schematic representation of a circuit topology of a first electrical system (or a portion thereof) of a motor vehicle with a DC-DC converter according to a first embodiment of the invention;

2 in a schematic representation of a circuit topology of a second electrical system of a motor vehicle (or a portion thereof) with a DC-DC converter according to a second embodiment of the invention;

3 in a schematic representation of a circuit topology of a third electrical system (or a portion thereof) of a motor vehicle with a in 2 illustrated DC-DC converter;

4 in a schematic representation of a circuit topology of a fourth electrical system (or a portion thereof) of a motor vehicle with a DC-DC converter according to a third embodiment of the invention;

5 in a schematic representation of a circuit topology of a fifth electrical system (or a portion thereof) of a motor vehicle with a DC-DC converter according to a fourth embodiment of the invention;

6 in a schematic representation of a circuit topology of a sixth electrical system (or a portion thereof) of a motor vehicle with a in 5 illustrated DC-DC converter;

7 in a schematic representation of a circuit topology of a seventh vehicle electrical system (or a portion thereof) of a motor vehicle with a DC-DC converter according to a fifth embodiment of the invention;

8th in a schematic representation of a circuit topology of an eighth electrical system (or a portion thereof) of a motor vehicle with a DC-DC converter according to a sixth embodiment of the invention.

Detailed description of the drawing:

1 shows a schematic representation of a circuit topology of a first electrical system BN1 (or a portion thereof) of a motor vehicle with a DC-DC converter GW1 according to a first embodiment.

The first vehicle electrical system BN1 comprises a first, a second and a third vehicle electrical system branch BZ1, BZ2, BZ3.

The first electrical system branch BZ1 includes sensitive power consumers, such. B. vehicle interior lighting, and has a first vehicle electrical system voltage U1 in the amount of, for example, 12 volts.

The second electrical system branch BZ2 includes high-performance power consumers, such. B. an electric motor for driving the motor vehicle, and has a second vehicle electrical system voltage U2 in the amount of, for example, 48 volts.

The third on-board network branch BZ3 includes, for example, a further high-performance DC consumer, such as a DC heater LD, which is supplied with power from the second on-board network branch BZ2.

The electrical system BN1 further includes a DC-DC converter GW1, which is electrically connected between the first, the second and the third board power supply branch BZ1, BZ2, BZ3.

The DC-DC converter GW1 comprises two first electrical connections A11, A12, via which the DC-DC converter GW1 is electrically connected to the first on-board network branch BZ1 and thus to the first vehicle electrical system voltage U1.

The DC-DC converter GW1 further comprises two second electrical connections A21, A22, via which the DC-DC converter GW1 is electrically connected to the second electrical system branch BZ2 and thus to the second vehicle electrical system voltage U2.

The DC-DC converter GW1 further comprises a third power connection A3, via which the DC-DC converter GW1 is electrically connected to the third onboard power supply branch BZ3 or to the DC heating LD.

The DC-DC converter GW1 further comprises three half-bridges HB1, HB2, HB3, which are respectively connected in parallel between the two second current terminals A21, A22 and each other.

The three half-bridges HB1, HB2, HB3 each have two controllable power semiconductor switches S1, S2; S3, S4; S5, S6, which are each connected in pairs between the two second power terminals A21, A22 and center tap M1, M2, M3 of the respective half-bridges HB1, HB2, HB3 to each other in series.

The center taps M1, M2, M3 of the three half bridges HB1, HB2, HB3 are electrically connected to a first (positive voltage side) of the two first power terminals A11 via circuit components to be described below.

The three half bridges HB1, HB2, HB3 are further electrically connected via a respective negative voltage side terminal NA to a second (negative voltage side) of the two first power terminals A12 and a second (negative voltage side) of the two second power terminals A22.

Via respective positive voltage side terminal PA, the three half bridges HB1, HB2, HB3 are further electrically connected to a first (positive voltage side) of the two second power terminals A21.

Between the first of the two first current connections A11 and the center taps M1, M2, M3 of the respective half-bridges HB1, HB2, HB3, the DC-DC converter GW1 in each case has a coil L1, L2, L3 (storage choke), which in each case between the first of the two first electrical connections A11 and the respective center taps M1, M2, M3 are electrically connected in series.

The respective half-bridges HB1, HB2, HB3 and the corresponding respective coils L1, L2, L3 and associated electrical connections, which connect the respective half-bridges HB1, HB2, HB3 with the respective corresponding coils L1, L2, L3 as well as with the two first and the two second power terminals A11, A12; A21, A22 electrically connect, respectively form a first, a second and a third voltage converter path SP1, SP2, SP3 for unidirectional / bidirectional voltage conversion between the first and the second board electrical system voltage U1, U2. These three voltage converter paths SP1, SP2, SP3 are independently controllable or controllable.

The DC-DC converter GW1 further comprises a first controllable (power) selection switch AS1 (or (power) switch), which is electrically connected in the first voltage converter path SP1 between a first coil L1 and the center tap M1 of a first half-bridge HB1 and a first, one second and a third switching terminal E1, E2, E3.

Via the first switching connection E1, the first selection switch AS1 is electrically connected to the first coil L1. The first selection switch AS1 is electrically connected to the center tap M1 of the first half-bridge H1 via the second switching connection E2. Thus, the first coil L1 and the first selection switch AS1 between the first of the two first power terminals A11 and the center tap M1 of the first half-bridge H1 are connected to each other in series electrically.

Via the third switching connection E3, the first selection switch AS1 is furthermore electrically connected to the third power connection A3.

The first selection switch AS1 comprises one or more contactors, relays, power semiconductor switches and / or other power switching elements, which are interconnected in a manner known to those skilled in the art and controlled so that the first selection switch AS1 driven by an external control signal respectively two or all of the three switching terminals E1, E2, E3 electrically connect to each other.

The DC-DC converter GW1 further includes a second controllable (power) selection switch AS2 (or power switch), which is electrically connected in the third voltage converter path SP3 between a third coil L3 and the center tap M1 of a third half-bridge HB3 and a fourth, a fifth and a sixth Switching connection E4, E5, E6 has.

Via the fourth switching connection E4, the second selection switch AS2 is electrically connected to the third coil L3. Via the fifth switching connection E5, the second selection switch AS2 is electrically connected to the center tap M3 of the third half-bridge H3. Thus, the third coil L3 and the second selection switch AS2 between the first of the two first power terminals A11 and the center tap M3 of the third half-bridge H3 are connected to each other in series electrically.

The second selection switch AS2 is also electrically connected to the third power connection A3 via the sixth switching connection E6.

The second selection switch AS2 likewise comprises one or more contactors, relays, power semiconductor switches and / or other power switching elements, which are interconnected and controllable in a manner known to those skilled in the art, that the second selection switch AS2 is controlled by a further external control signal two or all the three switching terminals E4, E5, E6 electrically connect to each other.

The DC-DC converter GW1 further comprises an energy management unit EM, which signal output side with the drive terminals of the respective power semiconductor switches S1, S2; S3, S4; S5, S6 of the three half bridges H1, H2, H3 and the respective selector switch AS1, AS2 is connected by signal technology and is set up, depending on selected operating modes of the electrical system BN1, the respective power semiconductor switches S1, S2; S3, S4; S5, S6 and the respective selection switch AS1, AS2 controlled to switch.

After the topology of the electrical system BN1 and the DC-DC converter GW1 based 1 has been described in detail, its function is described in more detail below:

The DC-DC converter GW1 is set up to perform, inter alia, three operating modes to be described below.

In a first operating mode, the DC-DC converter GW1 converts the first vehicle electrical system voltage U1 into the second vehicle electrical system voltage U2 or vice versa.

For operating the DC-DC converter GW1 in the first operating mode, the energy management unit EM switches off the two selection switches AS1, AS2, so that the three switching connections E1, E2, E3; E4, E5, E6 of the respective selector switch AS1, AS2 are electrically isolated from each other. In this first operating mode, therefore, only the second current path SP2 with the second coil L2 and the second half-bridge H2 is active. The energy management unit EM switches the two power semiconductor switches S3, S4 of the second half-bridge H2 on / off in a manner known to those skilled in the art and thus converts the first vehicle electrical system voltage U1 and into the second vehicle electrical system voltage U2 or vice versa (simple DCDC converter operation).

If during the voltage conversion between the two on-board network voltages U1, U2, a higher power flow between the first and the second board power supply branch BZ1, BZ2 desired, the power management unit EM switches either the first and / or the second selection switch AS1, AS2 in a switching state in which first switching terminal E1 of the first selection switch AS1 with the second switching terminal E2 of the corresponding selector switch AS1 or the fourth switching terminal E4 of the second selector switch AS2 are electrically connected to the fifth switching terminal E5 of the corresponding selector switch AS2. This activates the first and third current paths SP1, SP3 for voltage conversion. By appropriate control of the power semiconductor switches S1, S2; S5, S6 of the first and third half-bridges H1, H3, more current and thus also more electrical power are shifted from the first onboard power supply branch BZ1 into the second onboard power supply branch BZ2 or vice versa ("boost" operation of the DC voltage converter GW1).

In a second operating mode, the DC-DC converter GW1 supplies the DC heater LD in the third onboard power supply branch BZ3 with power from the second onboard power supply branch BZ2.

For operating the DC-DC converter GW1 in the second operating mode, the energy management unit EM switches the first and / or the second selection switch AS1, AS2 such that the second switching connection E2 of the first selection switch AS1 with the third switching connection E3 of the same selection switch AS1 and the fifth switching connection E5 with the sixth switching terminal E6 of the second selection switch AS2 are electrically connected. This will be a Power flow from the second electrical system branch BZ1, BZ2 to the third electrical system branch BZ3 and thus to the electric DC heater LD produced ("DC chopper" operation of the DC-DC converter GW1).

In a third operating mode, the DC-DC converter GW1 converts between the first and the second vehicle electrical system voltage U1, U2 and at the same time supplies the DC heater LD in the third vehicle electrical system branch BZ3 with power from the second vehicle electrical system branch BZ2.

For operating the DC-DC converter GW1 in the third operating mode, the energy management unit EM switches the first and / or the second selection switch AS1, AS2 such that all three switching connections E1, E2 and E3; E4, E5 and E6 of the respective selector switch AS1, AS2 are electrically connected to each other. As a result, all three on-board network branches BZ1, BZ2, BZ3 are electrically connected to one another and flow currents from the second on-board network branch BZ2 into the first and third on-board network branches BZ1, BZ3. The quantities of electrical power which are to flow from the second on-board network branch BZ2 into the first or third on-board network branch BZ1, BZ3 are controlled by the energy management unit EM by controlling the three half bridges H1, H2, H3 or their power semiconductor switches S1, S2; S3, S4; S5, S6 regulated in a manner known in the art (combined "Boost" and "DC chopper" operation of the DC-DC converter GW1).

2 shows in a further schematic representation of a circuit topology of a second electrical system BN2 (or a portion thereof) with a DC-DC converter GW2 according to a second embodiment.

The second vehicle electrical system BN2 differs from the first vehicle electrical system BN1 in 1 in that the third on-board network branch BZ3, instead of a high-power DC consumer, comprises a single-phase high-power AC consumer LD, such as a single-phase AC heater.

The DC-DC converter GW2 in 2 differs from the DC-DC converter GW1 in 1 in that it has a fourth power connection A4, which is electrically connected to the sixth switching connection E6 of the second selection switch AS2.

The AC load LD in the third electrical system branch BZ3 is electrically connected between the third and the fourth power connection A3, A4 of the DC voltage converter GW2.

With the in 2 shown DC-DC converter GW2 can in the second or the third operating mode instead of one in the in 1 In this embodiment, a so-called "AC chopper" operation can be realized, in which the single-phase high-power AC load LD is supplied with alternating current generated by the DC voltage converter GW2.

3 shows in a further schematic representation of a third electrical system BN3 (or a portion thereof) of a motor vehicle with a in 2 illustrated DC-DC converter GW2.

The third electrical system BN3 differs from the second electrical system BN2 in 2 in that the third on-board network branch BZ3 comprises an alternating-current charging cable LD instead of a single-phase AC consumer, via which the on-board network BN3 can charge on-board energy storage systems with alternating current. For charging the on-board network energy storage, the on-board network BZ is electrically connected via the AC charging cable LD to an external AC power system.

The DC-DC converter GW3 in 3 differs from the DC-DC converter GW2 in 2 in that the first and third coils L1, L3 are each electrically connected between the first electrical connection A11 and the first and third half-bridges H1, H2 (or their respective center tap M1, M3).

In this embodiment, with the DC-DC converter GW2 an "AC charging" operation can be realized, in which one or more not shown in the figure electric energy storage in the electrical system BN3 can be charged with AC from the vehicle external AC mains, the DC-DC converter GW2 means of first and third Spannungswanderpfades SP1, SP3 (or at least two current paths) converts the alternating current into direct currents. Thus, the motor vehicle can be charged by means of an on-board socket to a 230 volt AC power.

4 shows in a further schematic representation of a fourth electrical system BN4 (or a portion thereof) with a DC-DC converter GW3 according to a third embodiment.

The fourth board network BN4 differs from the third board network BN3 in 2 in that the third electrical system branch BZ3 instead of a single-phase AC consumer, a three-phase AC load LD, such as a three-phase electric motor, or a three-phase AC power source, such as a generator.

The three-phase AC consumer LD in the third electrical system branch BZ3 comprises three current phases, via which the AC consumer LD is electrically connected to the DC-DC converter GW3.

The DC-DC converter GW3 in 4 differs from the DC-DC converter in 2 in that it additionally comprises a fifth power connection A5 and is electrically connected via the third, the fourth and the fifth power connections A3, A4 and A5 to the respective ones of the three power phases of the AC load LD.

Furthermore, the DC-DC converter GW3 comprises a fourth voltage converter path SP4 with a fourth half-bridge H4 with two series-connected power semiconductor switches S7, S8 and a fourth coil L4. Further, the DC / DC converter GW3 includes a third (power) selection switch AS3 (or (power) changeover switch) which is electrically connected in the fourth voltage conversion path SP4 serially to the fourth coil L4.

The fourth half-bridge H4 is electrically connected with its two series-connected power semiconductor switches S7, S8 between the two second current terminals A21, A22 of the DC-DC converter GW3 parallel to the three half-bridges H1, H2, H3 described above. The fourth half-bridge H4 has a fourth middle connection M4, via which the two power semiconductor switches S7, S8 are connected in series to one another.

The fourth half-bridge H4 is electrically connected via the center connection H4 to the third selection switch AS3, the fourth coil L4 and furthermore to the first of the two first current connections A11 of the DC-DC converter GW3.

The third selection switch AS3 comprises a seventh, an eighth and a ninth switching connection E7, E8, E9. Via the seventh switching connection E7, the third selection switch AS3 is electrically connected to the fourth coil L4 and thus to the first of the two first current connections A11 of the DC-DC converter GW3. Via the eighth switching connection E8, the third selection switch AS3 is electrically connected to the middle connection M4 of the fourth half-bridge H4 and via the ninth switching connection E9 to the fifth power connection A5 of the DC-DC converter GW3.

5 shows in a further schematic representation of a fifth electrical system BN5 (or a portion thereof) with a DC-DC converter GW4 according to a fourth embodiment.

The on-board network BN5 comprises a first on-board network branch BZ1 in which there is a first vehicle electrical system voltage U1, a second vehicle electrical system branch BZ2 in which a second vehicle electrical system voltage U2 is present, and a third vehicle electrical system branch BZ3, which charges an alternating-current charging unit LD or an alternating-current charging cable for connecting the vehicle electrical system BN5 an external AC network.

The electrical system BN5 further includes the DC-DC converter GW4, which is electrically connected between the first, the second and the third board power supply branch BZ1, BZ2, BZ3.

The DC-DC converter GW4 comprises two first electrical connections A11, A12, via which the DC-DC converter GW4 is electrically connected to the first on-board electrical system branch BZ1 and thus to the first vehicle electrical system voltage U1.

The DC-DC converter GW4 further comprises two second electrical connections A21, A22, via which the DC-DC converter GW4 is electrically connected to the second electrical system branch BZ2 and thus to the second vehicle electrical system voltage U2.

The DC-DC converter GW4 further comprises a third and a fourth power connection A3, A4, via which the DC-DC converter GW4 is electrically connected to the third onboard power supply branch BZ3 or to the AC charging cable LD.

The DC-DC converter GW4 further includes a voltage converter path SP5 which is electrically connected between the two first power terminals A11, A12 on the one hand and the two second power terminals A21, A22 on the other hand and is adapted to convert the first vehicle electrical system voltage U1 into the second vehicle electrical system voltage U2 and / or vice versa.

In this embodiment, the voltage converter path SP5 of the DC-DC converter GW4 is in the form of a phase-shifted Zero Voltage Transition (ZVT) converter.

The voltage converter path SP5 thus comprises an H-switching bridge HS, which in turn comprises two half-bridges H6, H7, which are electrically connected to each other in parallel between the two first current terminals A11, A12. The two half-bridges H6, H7 each have two controllable power semiconductor switches S11, S12; S13, S14, which are in each case connected in series electrically in series via a respective middle connection M6, M7 in the respective half bridges H6, H7.

The H-switching bridge HS further comprises a bridge branch BZ, which is electrically connected between the center terminals M6, M7 of the two half-bridges H6, H7.

Between the first two power terminals A11, A12, the voltage converter path SP5 further comprises a capacitor C1, which is electrically connected in parallel to the H-switching bridge HS or to the two H-bridges H6, H7.

The DC-DC converter GW4 further comprises a (power) selection switch AS1 (or (power) switch) having a first, a second and a third switching terminal E1, E2, E3, which in series via the first and the second switching terminal E1, E2 Bridge branch BZ of H-switching bridge HS of voltage transformer path SP5 electrically connected. Via the third switching connection E3, the selection switch AS1 is electrically connected to the third power connection A3 of the DC-DC converter GW4.

The voltage converter path SP5 further includes a transformer TF1 having a primary coil PS and a secondary coil SS, wherein the primary coil PS is electrically connected in the bridge branch BZ of the H-switching bridge HS in series with the selection switch AS1.

The voltage converter path SP5 further comprises a second capacitor C2, which is electrically connected in the bridge branch BZ in series with the selection switch AS1 and the primary coil PS of the transformer TF1. Here, the primary coil PS connects the selection switch AS1 and the second capacitor C2 to each other electrically. In other words, the primary coil PS is located in the bridge branch BZ between the selection switch AS1 and the second capacitor C2.

The middle terminal M7 of one of the two half bridges H7 of the H switching bridge HS, which is electrically connected directly to the second capacitor C2, is also electrically connected to the fourth current terminal A4 of the DC voltage converter GW4.

The voltage converter path SP5 further comprises a further half-bridge H5, which in turn comprises two current connections HA1, HA2 and two controllable power semiconductor switches S9, S10 connected in series with each other via a center connection M5 between the two current connections HA1, HA2.

The half-bridge H5 is electrically connected to the secondary coil SS (or at its two ends) of the transformer TF1 and to a first of the two second current terminals A21 of the DC-DC converter GW4 via the two current connections HA1, HA2.

The half-bridge H5 is further electrically connected via the center connection M5 to a second of the two second current connections A22 of the DC-DC converter GW4.

The voltage converter path SP5 further comprises two coils L5, L6, which are each electrically connected between the first of the two second power terminals A21 of the DC-DC converter GW4 and one of the two power terminals HA1, HA2 of the half-bridge H5.

The voltage converter path SP5 further comprises a filter FT which is electrically connected between the two coils L5, L6 on the one hand and the first of the two second current terminals A21 of the DC voltage converter GW4 on the other hand.

The voltage converter path SP5 further comprises a third capacitor C3, which is electrically connected between the two second current terminals A21, A22 of the DC-DC converter GW4 and thus parallel to the filter FT, the two coils L5, L6 and the half-bridge H5.

The DC-DC converter GW4 further comprises an energy management unit EM, which in each case has a signal output with the control terminals of the respective power semiconductor switches S11, S12, S13, S14; S9, S10 of the H-switching bridge HS and the half-bridge H5 and is connected by signal technology with the control terminal of the selection switch AS1.

The operation of the DC-DC converter GW4 is similar to that of the in 1 represented the DC-DC converter GW1.

In the first mode of operation, the first and second switch terminals E1, E2 of the selector switch AS1 are electrically contacted with each other under the control of the power management unit EM, thereby operating the DC-DC converter GW4 in the simple DCDC converter operation.

In the second mode of operation, the first and third switch terminals E1, E3 of the selector switch AS1 are electrically contacted with each other under the control of the power management unit EM, whereby the DC-DC converter GW4 is operated in the aforementioned "DC chopper" mode.

If all three switching terminals E1, E2, E3 of the selection switch AS1 are electrically contacted with one another by the energy management unit EM, the DC-DC converter GW4 is operated in the combined DCDC converter and "DC chopper" mode.

6 shows in a further schematic representation of a circuit topology of a sixth electrical system BN6 (or a portion thereof) with an in 5 illustrated DC-DC converter GW4.

The sixth electrical system BN6 differs from the fifth electrical system BN5 described above in that the third electrical system branch BZ3 comprises a further transformer TF2 whose primary coil is electrically connected in series between the third and the fourth power connection A3, A4 of the DC-DC converter GW4. About this second transformer TF2 of the DC voltage converter GW4 is galvanically isolated from the third board power supply branch BZ3.

7 shows in a further schematic representation of a circuit topology of a seventh vehicle electrical system BN7 (or a portion thereof) with a DC-DC converter GW5 according to a fifth embodiment.

The seventh on-board network BN7 differs from the sixth on-board network BN6 described above in that the third onboard power supply branch BZ3 has a DC load LD instead of an AC charging cable, which is electrically connected to the DC voltage converter GW5 via the third power connection A3. The DC-DC converter GW5 in this seventh on-board electrical system BN7 has no fourth power connection.

8th shows in a further schematic representation of a circuit topology of eighth electrical system BN8 (or a portion thereof) with a DC-DC converter GW6 according to a sixth embodiment.

The DC-DC converter GW6 in 8th is different from the one in 5 or 6 in that instead of the second capacitor C2, it has a further (power) selection switch AS2 (or (power) changeover switch) which has a fourth, a fifth and a sixth switch connection E4, E5, E6 and via the fourth and fifth switch terminal E4, E5 between the center terminal M7 one of the two half-bridges H7 of the H-switching bridge HS and the primary coil PS of the transformer TF1 is electrically connected. Thus, the DC-DC converter GW6 two selection switches AS1, AS2, which are each electrically connected in one of the two electrical connections of the primary coil PS of the transformer TF1 to one of the two center terminals M6, M7 of the H-switching bridge HS.

Via the sixth switching connection E6, the second selection switch AS2 is electrically connected to the fourth power connection A4 of the DC-DC converter GW6.

The third on-board network branch BZ3 has a DC load LD, which is electrically connected between the third and the fourth power connection A3, A4 of the DC-DC converter GW6.

Claims (14)

A DC-DC converter (GW1, GW2, GW3, GW4, GW5, GW6) for converting between a first (U1) and a second (U2) voltage, comprising: - two first power connections (A11, A12) for connecting the DC-DC converter (GW1, GW2, GW3, GW4, GW5, GW6) to the first voltage (U1); - two second power terminals (A21, A22) for connecting the DC-DC converter (GW1, GW2, GW3, GW4, GW5, GW6) to the second voltage (U2); - At least a third power connection (A3) for switching or connecting the DC-DC converter (GW1, GW2, GW3, GW4, GW5, GW6) to at least one electrical device (LD); - At least a first voltage converter path (SP1, SP5, SP6), which between the two first power terminals (A11, A12) on the one hand and the two second power terminals (A21, A22) on the other hand electrically connected and is arranged between the first (U1) and the second (U2) voltage to convert; - At least a first controllable selection switch (AS1), which comprises at least a first (E1), a second (E2) and a third (E3) switching terminals and via the first (E1) and the second (E2) switching terminal serially in the at least one first voltage converter path (SP1, SP5) and via the third switching terminal (E3) to the at least one third power terminal (A3) is electrically connected; A power management unit (EM) for controlling the at least one first select switch (AS1) configured to selectively connect at least two of the first (E1), second (E2) and third (E3) switch terminals to each other electrically.  The DC-DC converter (GW1, GW2, GW3, GW4, GW5, GW6) according to claim 1, wherein the power management unit (EM) is further configured to unidirectionally convert the first (U1) and second (U2) voltages to the first one Switching connection (E1) to the second switching connection (E2) electrically connect.  A DC-DC converter (GW1, GW2, GW3, GW4, GW5, GW6) according to claim 1 or 2, wherein the power management unit (EM) is further configured to operate the at least one electrical device (LD) the third switching port (E3) with the first (E3). E1) and / or the second (E2) switching connection to connect electrically.  A DC-DC converter (GW1, GW2, GW3, GW4, GW5, GW6) according to any one of the preceding claims, wherein the power management unit (EM) is further adapted to uni- or bi-directionally convert between the first (U1) and second (U2) voltages and to simultaneously electrically connect the first (E1), second (E2) and third (E3) switching terminals for the simultaneous operation of the at least one electrical device (LD).  DC-DC converter (GW1, GW2, GW3) according to one of the preceding claims, wherein the at least one first voltage converter path (SP1) comprises a first half-bridge (H1) which is electrically connected between the two second power terminals (A21, A22) and two first controllable switches (S1, S2), wherein the two first switches (S1, S2) between the two second power terminals (A21, A22) and via a center terminal (M1) of the first half-bridge (H1) are electrically connected to each other in series, the at least one first selector switch (AS1) is electrically connected across the first (E1) and second (E2) switch terminals between the one of the first two power terminals (A11) and the middle terminal (M1) of the first half-bridge (H1).  The DC-DC converter (GW1, GW2, GW3) according to claim 5, wherein the at least one first voltage conversion path (SP1) further comprises a first inductor (L1) connected between one of the first two power terminals (A11) and the middle terminal (M1) of the first half-bridge (H1) is electrically connected in series to the at least one first selection switch (AS1).  A DC-DC converter (GW1, GW2, GW3) according to one of the preceding claims, further comprising a second voltage converter path (SP2) connected between the two first power terminals (A11, A12) on the one hand and the two second power terminals (A21, A22) on the other hand, and parallel to the at least one first voltage converter path (SP1) is electrically connected and is arranged to convert between the first (U1) and the second (U2) voltage.  DC-DC converter (GW2, GW3) according to one of the preceding claims, further comprising A fourth power terminal (A4) for connecting the DC-DC converter (GW2, GW3) to the at least one electrical device (LD); A third voltage converter path (SP3) which is electrically connected and arranged between the two first current terminals (A11, A12) on the one hand and the two second current terminals (A21, A22) on the other hand, and parallel to the at least one first voltage converter path (SP1), convert between the first (U1) and the second (U2) voltage; A second controllable selection switch (AS2) comprising a fourth (E4), a fifth (E5) and a sixth (E6) switching terminal and connected via the fourth (E4) and fifth (E5) switching terminals serially in the third voltage converter path (SP3 ) and is electrically connected to the third (A3) or fourth (A4) power terminal via the sixth switch terminal (E6); Wherein the power management unit (EM) is further configured to electrically connect at least two of the fourth (E4), fifth (E5) and sixth (E6) switch terminals, respectively.  DC-DC converter (GW3) according to one of the preceding claims, further comprising A fifth power terminal (A5) for connecting the DC-DC converter (GW3) to the at least one electrical device (LD); A fourth voltage converter path (SP4) which is electrically connected between the two first current terminals (A11, A12) on the one hand and the two second current terminals (A21, A22) on the other hand and is arranged in parallel to the at least one first voltage converter path (SP1), convert between the first (U1) and the second (U2) voltage; A third controllable selection switch (AS3) comprising a seventh (E7), an eighth (E8) and a ninth (E9) switching terminal and connected in series via the seventh (E7) and the eighth (E8) switching terminals in the fourth voltage conversion path (SP4 ) and is electrically connected via the ninth switching terminal (E9) to the fifth power terminal (A5); - wherein the power management unit (EM) is further configured to selectively connect at least two of the seventh (E7), an eighth (E8) and a ninth (E9) switching terminal to each other electrically. The DC-DC converter (GW4, GW5, GW6) according to one of the preceding claims, - wherein the at least one first voltage converter path (SP5) further comprises an H-switching bridge (HS), which is electrically connected between the two first power terminals (A11, A12) and a Bridge branch (BZ) comprises; - Wherein the at least one first selection switch (AS1) via the first (E1) and the second (E2) switching connection in the bridge branch (BZ) is connected in series electrically; - wherein the power management unit (EM) is further configured to switch the H-switching bridge (HS) controlled for conversion between the first (U1) and the second (U2) voltage.  The DC to DC converter (GW4, GW5, GW6) of claim 9, wherein the at least one first voltage conversion path (SP5) further comprises a transformer (TF1) having a primary coil (PS) and a secondary coil (SS), the primary coil (PS) in the bridge branch (BZ) are electrically connected in series with the at least one first selection switch (AS1) and the secondary coil (SS) between the two second power connections (A21, A22).  Vehicle electrical system (BN1, BN2, BN3, BN4, BN5, BN6, BN7, BN8), in particular for a motor vehicle, comprising: - A first electrical system branch (BZ1) with a first (electrical system) voltage (U1); - A second electrical system branch (BZ2) with a second (electrical system) voltage (U2); - A third Bordnetzzweig (BZ3) with at least one electrical device (LD); - a DC-DC converter (GW1, GW2, GW3, GW4, GW5, GW6) according to one of the preceding claims for converting between the first (U1) and the second (U2) (electrical system) voltage, which via the two first power connections (A11, A12) on the first vehicle electrical system branch (BZ1), via which two second electrical connections (A21, A22) are electrically connected to the second vehicle electrical system branch (BZ2), and via the at least one third electrical connection (A3) to the third vehicle electrical system branch (BZ3).  Vehicle electrical system (BN6) according to claim 12, wherein the DC-DC converter (GW4) is galvanically isolated from the third electrical system branch (BZ3).  Vehicle electrical system (BN1, BN2, BN3, BN4, BN5, BN6, BN7, BN8) according to claim 12 or 13, wherein the at least one electrical device (LD) a DC consumer, a single- or multi-phase AC load, a DC or AC charging port, a DC source, and / or comprises a single- or multi-phase AC power source.

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