Voltage network

Abstract

The invention relates to a voltage network (1) comprising at least one high-voltage battery (2) and at least two galvanically isolated DC / DC converters (3, 4), wherein the nominal output voltages of the two DC / DC converters (3, 4) are different, wherein the nominal voltage of the at least one first DC / DC converter (3) is 12 V, wherein the nominal voltage of the at least one second DC / DC converter (4) is more negative than -36 V, wherein at least one load (7) is connected to a 12 V output line (5) of the first DC / DC converter (3) and the negative output line (6) of the second DC / DC converter (4).

Description

[0001] The invention relates to a voltage network comprising at least one high-voltage battery and at least two galvanically isolated DC / DC converters.

[0002] Such voltage networks are known, for example, in electric vehicles. In these systems, a low-voltage voltage is provided via galvanically isolated DC / DC converters to supply power to the vehicle's electrical system. It is known that the two DC / DC converters provide different voltage levels or nominal output voltages, for example, 12 V and 48 V. Such a generic voltage network is disclosed, for example, in US 2023 / 0134237A1.

[0003] Another voltage network with two DC / DC converters with different nominal voltages is known from US 2024 / 0 283 249 A1.

[0004] DE 10 2016 220 120 A1 concerns an energy supply system, in particular for motor vehicles.

[0005] DE 10 2020 214 699 A1 concerns an electrical network in a motor vehicle.

[0006] The invention is based on the technical problem of further improving a generic voltage network.

[0007] The solution to the technical problem is achieved by a voltage network with the features of claim 1. Further advantageous embodiments of the invention are set out in the dependent claims.

[0008] The power supply network comprises at least one high-voltage battery and at least two galvanically isolated DC / DC converters. The high-voltage battery has a nominal voltage greater than 60 V, preferably greater than or equal to 200 V, 400 V, or higher. The nominal output voltages of the two DC / DC converters are different. The nominal voltage of the first DC / DC converter is 12 V. This voltage is used, for example, to supply a low-voltage electrical system with a low-voltage battery or a suitable energy storage device. Furthermore, the nominal voltage of the second DC / DC converter is lower than -36 V, with at least one load connected to a 12 V output of the first DC / DC converter and the negative output of the second DC / DC converter.This results in a voltage difference of over 48 V across the load, allowing the current to be reduced at the same power output compared to a DC / DC converter with a nominal voltage of 48 V, while the resulting total voltage remains below the touch voltage limit of 60 V. Depending on component tolerances, the nominal voltage at the second DC / DC converter can be reduced to -47.9 V. Preferably, the nominal voltage is equal to or less than -47.5 V.

[0009] In one embodiment, the 12 V output of the first DC / DC converter is fed back to a feedback input of the second DC / DC converter, the second DC / DC converter being configured to regulate its output voltage such that the sum of the output voltages of the first and second DC / DC converters is less than 60 V. It is assumed that the nominal voltage of the second DC / DC converter is more negative than -47.5 V (or down to -47.9 V). Thus, if, for example, the output voltage of the first DC / DC converter rises to 16 V, the second DC / DC converter regulates its voltage up to -43.5 V (or down to -43.9 V) so that the sum of the output voltages remains at 59.5 V (or down to 59.9 V). This takes advantage of the fact that many DC / DC converters have such feedback inputs to regulate their output voltage. Here, the output voltage of another DC / DC converter is used as a feedback signal to regulate the output voltage below 60 V as the total output voltage.The corresponding ratio can be adjusted using resistors.

[0010] In another embodiment, the at least two galvanically isolated DC / DC converters have a common primary winding, with two secondary windings connected in series on the secondary side. A center tap between the two secondary windings is connected to the ground terminals of the two rectifiers on the secondary side. This results in a compact design and saves components. The two ground terminals can also be referred to as terminal 31 and terminal 41, respectively.

[0011] In another embodiment, a further first DC / DC converter and a further DC / DC converter are provided, so that the voltage network on the LV side is redundant. The 12 V output line of the further first DC / DC converter can be fed back to the feedback input of the further second DC / DC converter, but this is not mandatory.

[0012] In another embodiment, the voltage network comprises at least two first DC / DC converters and at least two second DC / DC converters, wherein at least one first DC / DC converter and at least one second DC / DC converter share a common inverter and a common primary winding, and at least one further first DC / DC converter and at least one further second DC / DC converter share another common inverter and another common primary winding. Preferably, the outputs of the first DC / DC converters are connected to each other on the secondary side, and the outputs of the second DC / DC converters are connected to each other on the secondary side. This distributes the power and simultaneously ensures redundancy, while the multiple primary windings also allow for better weight distribution on a printed circuit board. More than two first and second DC / DC converters can also be provided, e.g., four or eight.

[0013] In a further embodiment, at least one control circuit for the inverters on the primary side is designed to control the inverters with a time offset, so that ripple on the DC voltage side at the high-voltage battery is reduced.

[0014] In another embodiment, the at least one consumer includes an electric machine. The consumer can be, for example, a drive motor or an air conditioner.

[0015] The invention is explained in more detail below with reference to preferred embodiments. The figures show: Fig. 1. A schematic block diagram of a voltage network, Fig. 2 a schematic block diagram of a first embodiment and Fig. 3 a schematic block diagram of a second embodiment.

[0016] In the Fig. Figure 1 shows an electrical voltage network 1. The voltage network 1 comprises a high-voltage battery 2 and two galvanically isolated DC / DC converters 3 and 4. The nominal output voltage of the first DC / DC converter 3 is 12 V. The nominal output voltage of the second DC / DC converter 4 is equal to or less than -47.5 V. The 12 V output line 5 and the -47.5 V output line 6 are connected to a load 7, which then receives a voltage of 59.5 V or more, but less than 60 V. The first DC / DC converter 3 also supplies an on-board electrical system with an on-board battery 8. The high-voltage battery 2 is further shown to be connected to an inverter 9, which supplies an electric motor 10 with a three-phase AC voltage. A DC link capacitor 11 is connected in parallel to the DC input of the inverter 9.It is further shown that the 12 V output line 5 of the first DC / DC converter 3 is connected to a feedback input 12 of the second DC / DC converter 4, so that the latter regulates its output voltage depending on the voltage on the 12 V output line 5.

[0017] In the Fig. Figure 2 shows a first embodiment in which the two DC / DC converters 3, 4 are partially fused. The two DC / DC converters 3, 4 have a common inverter 13 and a common primary winding 14 on the primary side. On the secondary side, two secondary windings 15, 16 are connected in series, with their center tap 17 serving as a common ground connection. The first DC / DC converter 3 has a first rectifier 18, at the output of which the nominal output voltage of 12 V is present. Similarly, the second DC / DC converter 4 has a second rectifier 19, at the output of which the nominal output voltage of -47.5 V (up to -47.9 V) is present. A vehicle electrical system load 20 is also shown. The advantage of this circuit is that the two DC / DC converters 3, 4 have a common primary side, and a common ground can be easily established via the center tap 17.Consumer 7 can then be supplied with a voltage just below the touch voltage of 60 V, allowing it to be operated at a higher power output or, at the same power output, at a lower current. Furthermore, the voltage network 1 includes another first DC / DC converter 21 and another second DC / DC converter 22. The second and second DC / DC converters 21 and 22 use the same inverter 13 and the same primary winding 14. The second first DC / DC converter 21 has a rectifier 23, and the second DC / DC converter 22 has a second rectifier 24, at which the nominal output voltages of 12 V and -47.5 V, respectively, are again applied. The second first DC / DC converter 21 and the second DC / DC converter 22 serve as backups and also have two secondary windings 25 and 26 connected in series with a center tap 27.

[0018] In the Fig. Figure 3 shows another alternative embodiment. Regarding the design of the first DC / DC converter 3 and the second DC / DC converter 4, reference can be made to the descriptions in Figure 3. Fig. 2 Reference is made to Figure 2, whereby the on-board battery is not shown. In contrast to the embodiment according to Fig. In Figure 2, the additional first DC / DC converter 21 and the additional second DC / DC converter 22 each have their own inverter 28 and their own primary winding 29. As indicated by the dots, several additional first and second DC / DC converters 21, 22 can also be present. On the output side, all first DC / DC converters 3, 21 are connected in parallel, and all second DC / DC converters 4, 22 are connected in parallel. A control circuit 30 for the inverters 13, 28 is arranged on the primary side, which controls the inverters 13, 28 with a time offset to reduce the ripple at the high-voltage battery 2. The primary windings 14, 29 can be selected to be smaller than the single primary winding 14 according to Figure 2. Fig. 2. It should also be noted that the DC / DC converters 3, 4, 21, 22 can be bidirectional. The inverters 13, 28 are preferably designed as full-bridge inverters. Reference symbol list 1 electrical voltage network 2 high-voltage batteries 3 first DC / DC converter 4 second DC / DC converter 5 12 V output line 6-47.5V output line 7 consumers 8 On-board battery 9 inverters 10 Electric machine 11 Intermediate circuit capacitor 12 Feedback Input 13 inverters 14 Primary winding 15 Secondary winding 16 Secondary winding 17 Center tap 18 first rectifier 19 second rectifier 20 On-board electrical consumers 21 more first DC / DC converters 22 additional second DC / DC converters 23 first rectifier 24 second rectifier 25 Secondary winding 26 Secondary winding 27 Center tap 28 inverters 29 Primary winding 30 Control circuit

Claims

[1] Voltage network (1) comprising at least one high-voltage battery (2) and at least two galvanically isolated DC / DC converters (3, 4), wherein the nominal output voltages of the two DC / DC converters (3, 4) are different, wherein the nominal voltage of the at least one first DC / DC converter (3) is 12 V, characterized by , that the nominal voltage of the at least one second DC / DC converter (4) is more negative than -36 V, wherein at least one load (7) is connected to a 12 V output line (5) of the first DC / DC converter (3) and the negative output line (6) of the second DC / DC converter (4). [2] Voltage network (1) according to claim 1, characterized by, that the 12 V output line (5) of the first DC / DC converter (3) is fed back to a feedback input (12) of the second DC / DC converter (4), wherein the second DC / DC converter (4) is configured to regulate its output voltage such that the sum of the output voltages of the first DC / DC converter (3) and the second DC / DC converter (4) is less than 60 V. [3] Voltage network (1) according to any of the preceding claims, characterized by , that the at least two galvanically isolated DC / DC converters (3, 4) have a common primary winding (14), wherein on the secondary side two secondary windings (15, 16) are connected in series, wherein a center tap (17) between the two secondary windings (15, 16) is connected to ground terminals of the two rectifiers (18, 19) on the secondary side. [4] Voltage network (1) according to any of the preceding claims, characterized by, that a further first DC / DC converter (21) and a further second DC / DC converter (22) are provided. [5] Voltage network (1) according to claim 4, characterized by , that the four DC / DC converters (3, 4, 21, 22) have a common primary winding (14), wherein on the secondary side two further secondary windings (25, 26) are connected in series, wherein a center tap (27) between the two further secondary windings (25, 26) is connected to ground terminals of the two further rectifiers (23, 24). [6] Voltage network (1) according to any of the preceding claims, characterized by, that the voltage network (1) has at least two first DC / DC converters (3, 21) and at least two second DC / DC converters (4, 22), wherein at least one first DC / DC converter (3) and at least one second DC / DC converter (4) have a common inverter (13) and a common primary winding (14) and at least one further first DC / DC converter (22) have a further common inverter (28) and a further common primary winding (29). [7] Voltage network (1) according to claim 6, characterized by , that the outputs of the first DC / DC converters (3, 21) are connected to each other on the secondary side and the outputs of the second DC / DC converters (4, 22) are connected to each other on the secondary side. [8] Voltage network (1) according to claims 6 and 7, characterized by , that at least one control circuit (30) is designed on the primary side to control the inverters (13, 28) with a time offset. [9] Voltage network (1) according to any of the preceding claims, characterized by , that at least one consumer (7) has an electric machine (10).

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