阅读说明：本技术 供电系统 (Power supply system ) 是由 S·布鲁梅 S·内斯科 D·乌克威克 于 2021-07-05 设计创作，主要内容包括：为了提供更有效的供电系统(1),供电系统(1)包括整流器(8)、低压逆变器(2)和低压执行器(4),其中,整流器(8)构造为将主交流电压(u、v、w)转换为低输入直流电压(Ue),其中,低压逆变器(2)与整流器(8)连接,并构造为将低输入直流电压(Ue)转换为低供应交流电压(uv1),并且其中,低压逆变器(2)与低压执行器(4)连接,从而通过低供应交流电压(uv1)为低压执行器(4)供电。根据本发明,还设有直流电压转换器(3),它与整流器(8)连接,并构造为将低输入直流电压(Ue)转换为特低直流电压(Uz)。特低压逆变器(5)与直流电压转换器(3)连接,并构造为将特低直流电压(Uz)转换为特低供应交流电压(uv2)。特低压逆变器(5)与特低压执行器(6)连接,从而通过特低供应交流电压(uv2)向特低压执行器(6)供电。(In order to provide a more efficient power supply system (1), the power supply system (1) comprises a rectifier (8), a low-voltage inverter (2) and a low-voltage actuator (4), wherein the rectifier (8) is configured to convert a main alternating voltage (u, v, w) into a low input direct voltage (Ue), wherein the low-voltage inverter (2) is connected to the rectifier (8) and configured to convert the low input direct voltage (Ue) into a low supply alternating voltage (uv1), and wherein the low-voltage inverter (2) is connected to the low-voltage actuator (4) in order to supply the low-voltage actuator (4) with the low supply alternating voltage (uv 1). According to the invention, a direct-current voltage converter (3) is also provided, which is connected to the rectifier (8) and is designed to convert the low input direct-current voltage (Ue) into an ultra-low direct-current voltage (Uz). The extra-low voltage inverter (5) is connected to the direct voltage converter (3) and is configured to convert the extra-low direct voltage (Uz) into an extra-low supply alternating voltage (uv 2). The extra-low voltage inverter (5) is connected to the extra-low voltage actuator (6) so as to supply power to the extra-low voltage actuator (6) via an extra-low supply alternating voltage (uv 2).)

1. A power supply system (1) comprising: -a rectifier (8), -a low-voltage inverter (2) and-a low-voltage actuator (4), wherein the rectifier (8) is configured to convert a main alternating voltage (u, v, w) into a low input direct voltage (Ue), wherein the low-voltage inverter (2) is connected to the rectifier (8) and is configured to convert the low input direct voltage (Ue) into a low supply alternating voltage (uv1), and wherein the low-voltage inverter (2) is connected to the low-voltage actuator (4) in order to supply the low-voltage actuator (4) with the low supply alternating voltage (uv1), characterized in that a direct-voltage converter (3) is provided which is connected to the rectifier (8) and is configured to convert the low input direct voltage (Ue) into an extra-low direct voltage (Uz); an extra-low voltage inverter (5) is provided, which is connected to the direct voltage converter (3) and is designed to convert the extra-low direct voltage (Uz) into an extra-low supply alternating voltage (uv2), wherein the extra-low voltage inverter (5) is connected to an extra-low voltage actuator (6) in order to supply the extra-low voltage actuator (6) with power via the extra-low supply alternating voltage (uv 2).

2. Power supply system (1) according to claim 1, characterized in that the dc voltage converter (3) is connected to the low voltage inverter (2) via a supply connection (10) to supply operating power to the low voltage inverter (2) via an extra low dc voltage (Uz).

3. Power supply system (1) according to claim 1 or 2, characterized in that the direct voltage converter (3) is an integral part of the rectifier (8).

4. Power supply system (1) according to one of the claims 1 to 3, characterized in that the direct voltage converter (3) is implemented isolated.

5. Power supply system (1) according to one of the claims 1 to 4, characterized in that the direct voltage converter (3) is implemented bidirectional.

6. Power supply system (1) according to claim 5, characterized in that the direct voltage converter (3) comprises an inverter unit (30) for converting a low input direct voltage (Ue) into a primary voltage (Ue1), in that the direct voltage converter (3) comprises a transformer unit (31) connected to the inverter unit (30) for converting a primary alternating voltage (Ue1) into a secondary alternating voltage (Ue2), and in that the direct voltage converter (3) comprises a rectifier unit (32) connected to the transformer unit (31) for converting the secondary voltage (Ue2) into the ultra-low direct voltage (Uz).

7. Power supply system (1) according to any one of claims 1 to 6, characterized in that the low-voltage actuator (4) is part of a movement system, a machine tool or a rotating electrical machine.

8. Power supply system (1) according to any of the claims from 1 to 7, characterized in that said extra low voltage actuator (6) is part of a long stator linear motor.

9. Power supply system (1) according to any one of claims 1 to 7, characterized in that the extra-low voltage actuator (6) is part of a planar motor.

10. Power supply system (1) according to any one of claims 1 to 7, characterized in that the extra low voltage actuator (6) is part of an extra low voltage rotating electrical machine.

11. Power supply system (1) according to any one of claims 1 to 10, characterized in that a first plurality of extra-low voltage inverters (5) with associated extra-low voltage actuators (6) is provided, wherein the first plurality of extra-low voltage inverters (5) is connected with the direct voltage converter (3) in order to convert the input extra-low voltage direct current (Uz) into a corresponding extra-low supply alternating voltage (uv2) and in order to supply the extra-low supply alternating voltage (uv2) to the associated extra-low voltage actuators (6).

12. Power supply system (1) according to one of the claims 1 to 11, characterized in that a second plurality of low-voltage inverters (2) with associated low-voltage actuators (4) is provided, wherein the second plurality of low-voltage inverters (2) is connected with the rectifier (8) for converting the low input direct voltage (Ue) into a corresponding low supply alternating voltage (uv1) and for supplying the low supply alternating voltage (uv1) to the associated low-voltage actuators (4) respectively.

13. Method for supplying an ultra-low voltage actuator (6) and a low voltage actuator (4), wherein a rectifier (8) converts a main alternating voltage (u, v, w) into a low input direct voltage (Ue) and a low voltage inverter (2) converts the low input direct voltage (Ue) into a low supply alternating voltage (uv1) for supplying the low voltage actuator (4) with the low supply alternating voltage (uv1), characterized in that the low input direct voltage (Ue) is converted by a direct voltage converter (3) into an ultra-low direct voltage (Uz) and the ultra-low voltage inverter (5) converts the ultra-low direct voltage (Uz) into an ultra-low supply alternating voltage (uv2) for supplying the ultra-low voltage actuator (6) with the ultra-low supply alternating voltage (uv 2).

14. The method according to claim 13, characterized in that the excess energy at the extra-low voltage actuator (6) is passed through the extra-low voltage inverter (5), the direct voltage converter (3),

-and fed into the low-voltage actuator (4) through the low-voltage inverter (2),

and/or

-fed into a power supply network through the rectifier (8).

15. The method as claimed in claim 13 or 14, characterized in that the excess energy at the low-voltage actuator (6) is passed through the low-voltage inverter (2),

-fed into the extra-low voltage actuator (6) through the direct voltage converter (3) and through the extra-low voltage inverter (5),

and/or

-fed into a power supply network through the rectifier (8).

Technical Field

The invention relates to a power supply system comprising a rectifier, a low-voltage inverter and a low-voltage actuator, wherein the rectifier is designed to convert a main alternating voltage (mains alternating voltage) into a low input direct voltage, wherein the low-voltage inverter is connected to the rectifier and is designed to convert the input low direct voltage into a low supply alternating voltage, and wherein the low-voltage inverter is connected to the low-voltage actuator in order to supply the low-voltage actuator with the low supply alternating voltage. The invention further relates to a method for supplying low-voltage actuators and extra-low-voltage actuators, wherein a rectifier converts a main ac voltage into a low input dc voltage and a low-voltage inverter converts the low input dc voltage into a low supply ac voltage, so that the low-voltage actuators are supplied with the low supply ac voltage.

Background

Direct Current (DC) voltages and Alternating Current (AC) voltages are generally divided into different voltage ranges. The Voltage range of the ultra low direct Voltage is 0 to 120V DC, wherein, although 0 to 60V DC can also be provided according to DVC-a (critical Voltage Classification a), reference is made to the standard EN 61800-5-1. The extra low alternating voltage is in the range of 0 to 50V AC. In contrast, the low DC voltage is in the range of 120 to 1500V DC, while the low AC voltage is in the range of 50 to 100V AC. The high direct current voltage is in the range of 1500V DC or more, and the high alternating current voltage is in the range of 1000V AC or more.

The main alternating voltage of the supply network is in the low voltage range, preferably 230V AC, 400V AC or 480V AC. In contrast, low-voltage actuators require low supply AC voltages of 500 to 800V AC, depending on the embodiment. Therefore, a power supply system is needed to convert the main ac voltage into a low supply ac voltage suitable for the low voltage actuator, which can be provided to the low voltage actuator. In principle, each low-voltage actuator can be connected directly to the supply network by means of one or more low-voltage transformer direct converters. These low-voltage transformers or direct converters therefore convert the main ac voltage of the supply network directly into a low supply ac voltage for supply to the low-voltage actuators, which is of course uneconomical. In order to create a more cost-effective topology, rectifiers are often provided in the supply system for the supply of the low-voltage actuators. The rectifier converts the main ac voltage to a low input dc voltage. However, since the low-voltage actuator requires a low supply alternating-current voltage, a low-voltage inverter that converts a low input direct-current voltage into a low supply alternating-current voltage is further provided. The low supply ac voltage is in turn supplied to the associated low-voltage actuator. Usually, a low-voltage inverter is assigned to each low-voltage actuator, wherein the low-voltage inverters draw a low input dc voltage from the same rectifier.

However, in long stator linear motors, planar motors, smaller rotating electrical machines, and the like, extra low voltage actuators are often installed, and their operation requires extra low supply ac voltage. Thus, in known power supply systems, a further rectifier is often provided, which converts the main alternating voltage into a low direct voltage, which is in turn supplied to the extra-low voltage inverter. The extra low voltage inverter converts the low dc voltage to a low supply ac voltage and provides it to the extra low voltage actuator.

Disclosure of Invention

The object of the present invention is to provide an alternative power supply system which makes it possible to supply actuators with different supply voltages.

According to the invention, this object is achieved in that: the method comprises the steps of providing a direct-current voltage converter connected with a rectifier and configured to convert a low input direct-current voltage into an ultra-low direct-current voltage, wherein an ultra-low voltage inverter is provided, the ultra-low voltage inverter is connected with the direct-current voltage converter and configured to convert the ultra-low direct-current voltage into an ultra-low supply alternating-current voltage, and the ultra-low voltage inverter is connected with an ultra-low voltage actuator so as to supply power to the ultra-low voltage actuator through the ultra-low supply alternating-current voltage. Furthermore, the object is achieved by the following method: the low input DC voltage is converted to an extra low DC voltage by a DC voltage converter (DC-DC converter), and the extra low voltage inverter converts the extra low DC voltage to an extra low supply ac voltage to power the extra low voltage actuator with the extra low supply ac voltage.

Thus, on the one hand, the low-voltage actuator is supplied from the mains alternating voltage (for example, supplied by the supply network) through the rectifier and the low-voltage inverter, while on the other hand, the extra-low-voltage actuator is supplied through the same rectifier, direct-voltage converter and extra-low-voltage inverter. Since the dc voltage converter converts the low input dc voltage provided by the rectifier to an ultra low dc voltage, there is no need for any other rectifier to convert the main ac voltage to an ultra low dc voltage. The rectifier is preferably designed for converting a mains alternating voltage of 220 to 480V AC ± 10% to a low input direct voltage of 120 to 1500V DC, preferably 250 to 900V DC, more preferably 500 to 900V DC. The power supply system can therefore be used for many power supply systems existing worldwide (TT systems, TN-S systems, TN-C-S systems with a three-phase main alternating voltage in the range 220 to 480V AC ± 10%). Since the required levels of the low input dc voltage and the ultra-low dc voltage are known in advance, a dc voltage converter with a smaller voltage range can be used. This also results in a high efficiency of the dc voltage converter.

Preferably, the dc voltage converter is connected to the low-voltage inverter via a supply connection, so that the low-voltage inverter is supplied with operating power (operating energy/operating power) via the extra low dc voltage. As with the extra-low voltage inverter, it is necessary to supply operating power to the low voltage inverter in order to ensure basic functions, i.e., supply (power supply) to the control unit and the switching unit. Since the extra low dc voltage to be converted is already present on the input side of the extra low voltage inverter, this extra low dc voltage is used to tap off the operating power of the extra low voltage inverter and to ensure its functioning. Therefore, the low-voltage inverter can also supply running power by an ultra-low direct-current voltage through the supply connection.

The dc voltage converter may be an integral part of the rectifier or may be embodied as a separate unit (device). Preferably, the dc voltage converter is implemented as isolated and/or bidirectional.

Bidirectional dc voltage converters are known, however, have been used to date to power batteries, Uninterruptible Power Supplies (UPS), and Battery Electric Vehicles (BEV). In the case of supplying a battery or an uninterruptible power supply, a low input direct voltage (essentially 500-1000V DC) is present at the input side and converted to an output very low direct voltage (24-48V DC) at the output side.

Preferably, the excess energy at the extra-low voltage actuator is supplied (fed) into the low voltage actuator via the extra-low voltage inverter, the direct voltage converter and via the low voltage inverter.

If the extra-low voltage inverter and the dc voltage converter are implemented bidirectional, energy can flow not only from the input side of the dc voltage converter (where a low input dc voltage is present) to the output side of the dc voltage converter (where an extra-low dc voltage is present) but also from the output side to the input side. Thus, not only can the extra-low voltage actuator be supplied from the supply network via the rectifier, the dc voltage converter and the extra-low voltage inverter, but also the extra-low voltage actuator can be supplied via the extra-low voltage inverter and the dc voltage converter, i.e. to the low-input dc voltage and thus in turn to the low-voltage actuator via the low-voltage inverter. It is therefore possible to transfer electrical energy from extra low voltage actuators to low voltage actuators, which is why the system efficiency is increased by a bidirectional dc voltage converter, since extra low voltage actuators, in particular long stator linear motors and planar motors, often have dynamic load curves. Thus, there may be excess energy at the extra low pressure actuator, for example, generated by the braking process.

Preferably, the excess energy at the extra-low voltage actuator is fed back into the supply network via an extra-low voltage inverter, a dc voltage converter and via a rectifier. Thereby, the excess energy does not have to be destroyed (dissipated) and is therefore not lost, thereby increasing the efficiency of the power supply system. This feedback is particularly possible if the extra low voltage inverter, the dc voltage converter and the rectifier are bi-directional.

If the dc voltage converter is not implemented to be bi-directional (i.e., unidirectional), any excess energy present at the extra low voltage actuator can be dissipated (dissipated/dissipated) at the extra low voltage actuator. However, if a bidirectional extra-low voltage converter is provided, the excess energy (in the case of a unidirectional direct-current voltage converter, and also in the case of a bidirectional direct-current voltage converter) can also be converted back to an extra-low intermediate voltage and supplied to a further extra-low voltage actuator via a further extra-low voltage inverter, or, if a supply connection is provided for supplying the low-voltage inverter with operating power (operating energy), the excess energy is at least partially used as operating power.

Preferably, the excess energy at the low-voltage actuator is supplied to the extra-low-voltage actuator by the low-voltage inverter, via the dc voltage converter, and by the extra-low-voltage inverter, and/or the excess energy at the low-voltage actuator is supplied to the supply network by the low-voltage inverter and by the rectifier.

If the low-voltage inverter is designed to be bidirectional, energy feedback from the low-voltage actuator is possible, wherein energy can be fed back into the supply network via a bidirectional rectifier and/or energy can be fed to the extra-low-voltage actuator via a dc converter and an extra-low-voltage inverter.

Preferably, the dc voltage converter includes an inverter unit converting a low input dc voltage into a primary ac voltage, a transformer unit connected to the inverter unit to convert the primary ac voltage into a secondary ac voltage, and a rectifier unit connected to the transformer unit to convert the secondary ac voltage into an ultra-low dc voltage.

In order to provide a bidirectional dc voltage converter and to keep the number of electronic components used low, a double active bridge embodiment is advantageous. Preferably, the dual active bridge is implemented as a single stage and is controlled using three-level modulation. Thus, a high voltage range can be covered by a low input dc voltage, whereby the dc voltage converter can be connected to a supply network with different main ac voltages via suitable rectifiers. Furthermore, high dynamics are ensured by the dc voltage converter as a double active bridge. If the dual active bridges are implemented symmetrically, i.e. the dc voltage-ac voltage bridge and the ac voltage-dc voltage bridge are implemented identically, power symmetry is given by the dc voltage converter, which means that electrical energy can be fed in and fed back in the same amount. The power range of such a dc voltage converter is preferably up to 2kW with a repeated peak load capacity of 3 kW.

The low voltage actuator may be part of a motion system, a machine tool, or a rotating motor.

The extra low voltage actuator may be part of a long stator linear motor, a planar motor or an extra low voltage rotary motor.

Preferably, a first plurality of extra-low voltage inverters with associated extra-low voltage actuators is provided, wherein the first plurality of extra-low voltage inverters are connected to the dc voltage converter in order to convert the extra-low dc voltage into a corresponding extra-low supply ac voltage and to supply the associated extra-low supply ac voltage to the associated extra-low voltage actuators. Thus, the extra low direct voltage may serve as a central connection point of the first plurality of extra low voltage inverters and the associated extra low voltage actuators. The extra low supply ac voltages of the respective extra low voltage actuators may be the same or different.

Preferably, a second plurality of low-voltage inverters with associated low-voltage actuators is provided, wherein the second plurality of low-voltage inverters are connected to a rectifier in order to convert the low input dc voltage into a corresponding supply low ac voltage and to supply the associated low-voltage actuators with the low supply ac voltage in each case. Thus, the low input dc voltage may serve as a central connection point for the first plurality of low-voltage inverters and associated low-voltage actuators. The low supply ac voltages of the respective low voltage actuators may be the same or different.

Drawings

The invention will be explained in more detail hereinafter with reference to fig. 1 to 5, which fig. 1 to 5 show by way of example, schematically and without limitation, advantageous design configurations of the invention. Shown in the attached drawings:

figure 1 shows a power supply system according to the prior art,

figure 2 shows a power supply system according to the invention,

figure 3 shows a power supply system with a supply connection,

FIG. 4 illustrates a power supply system having multiple inverters and actuators

Fig. 5 shows a preferred embodiment of the dc voltage converter.

Detailed Description

Fig. 1 shows a power supply system 1 according to the prior art. A low-voltage actuator 4 is provided, which is supplied with a low supply alternating voltage uv1 (for example, in the range of 50 to 1000V AC, preferably in the range of 500 to 800V AC). For example, the low pressure actuator 4 may be part of a motion system, a machine tool, or a rotating motor, etc.

Further, an extra low voltage actuator 6 is provided, and an extra low supply alternating voltage uv2 (for example, in the range of 0 to 50V AC) is supplied to the extra low voltage actuator 6. The extra low voltage actuator 6 may be part of a long stator linear motor, a planar motor, a rotating electrical machine (each designed for extra low supply ac voltage uv2), etc.

In order to provide the low supply ac voltage uv1, a low-voltage inverter 2 is provided, which low-voltage inverter 2 is connected to the low-voltage actuator 4 and thus supplies the low-voltage actuator 4 with the low supply ac voltage uv 1. On the other hand, in order to provide the extra-low supply ac voltage uv2, an extra-low voltage inverter 5 is provided, which extra-low voltage inverter 5 is connected to the extra-low voltage actuator 6 and thereby supplies the extra-low supply ac voltage uv2 to the extra-low voltage actuator 6.

Furthermore, a rectifier 8 is provided, which rectifier 8 is designed and designed to convert the main ac voltages u, V, w (in this case three-phase) into a low input DC voltage Ue (120 to 1500V DC). The main alternating voltages u, V, w are preferably present as low alternating voltages (i.e. in the range of 50 to 1000V AC) and are provided, for example, by a supply network.

The rectifier 8 is connected to the low-voltage inverter 2 and supplies the low-voltage inverter 2 with a low input dc voltage Ue. The low-voltage inverter 2 converts the low input dc voltage Ue into a low supply ac voltage uv1, which is supplied to the low-voltage actuator 4 at uv 1.

However, the extra low voltage inverter 5 requires an extra low input dc voltage Uz to convert it to an extra low supply AC voltage uv2(0 to 50V AC) and to supply the extra low voltage actuator 6. Therefore, a further rectifier 8 'is provided, which rectifier 8' is designed and configured to convert the main alternating voltage u, V, w into an extra low direct voltage Uz (in the range of 0 to 120 vdc, preferably 24 to 60 vdc). The further rectifier 8' thus supplies the extra low voltage dc voltage Uz to the extra low voltage inverter. The extra low voltage inverter 5 converts the extra low input dc voltage Uz into an extra low supply ac voltage uv2, which is supplied to the extra low voltage actuator 6 uv 2.

In general, in fig. 1, the extra low voltage actuator 4 is supplied by a rectifier 8 and the low voltage inverter 2, whereas the low voltage actuator 4 is supplied by another rectifier 8' and the extra low voltage inverter 2.

In contrast, fig. 2 shows a power supply system 1 according to the invention. As in fig. 1, a rectifier 8 is provided, which rectifier 8 is designed and constructed to convert the main alternating voltages u, V, w into a low input direct voltage Ue (120 to 1500V DC). Further, like fig. 1, the low input direct-current voltage Ue is converted by the low-voltage inverter 2 into a low supply alternating-current voltage uv1 (in the range of 50 to 1000V AC, preferably in the range of 560 to 800V AC) and supplied to the low-voltage actuator 4.

In contrast to fig. 1, however, in fig. 2, according to the invention, a dc voltage converter 3 is provided for supplying an extra low voltage actuator 6, which dc voltage converter 3 is connected to a rectifier 8 and to an extra low voltage inverter 5. The DC voltage converter 3 may be an integral part of the rectifier 8 and is designed and constructed to convert the low input DC voltage Ue provided by the rectifier 8 into an ultra-low DC voltage Uz (in the range of 0 to 120V DC, preferably 0 to 60V DC). The extra low dc voltage is supplied by the dc voltage converter 3 to the extra low voltage inverter 5. The extra low voltage inverter 5 is in turn connected to the extra low voltage actuator 6 and is correspondingly designed and configured to convert the extra low direct voltage Uz into an extra low supply alternating voltage uv2 (in the range of 0 to 50V AC) and to supply it to the extra low voltage actuator 6.

Whereby no further rectifier 8' is required to supply the extra low voltage inverter 5. Instead, the extra low voltage actuator 6 is supplied via the already existing rectifier 8, the dc voltage converter 3 and finally the extra low voltage inverter 5.

Each inverter is required to function as it supplies operating power (operating power) to the associated control unit, switching unit, etc. The extra-low voltage inverter 5 can use the extra-low dc voltage Uz already present on its input side and derive its operating power therefrom. Preferably, the output side of the dc voltage converter 3 is not only connected to the input side of the extra-low voltage inverter 2, but also to the low voltage inverter 2 via a supply connection (supply connection) 10, as shown in fig. 3. The low-voltage inverter 2 is supplied with operating power via an extra low dc voltage Uz by means of a supply connection (supply connection) 10.

The low dc voltage Ue can also be supplied by the rectifier 8 to a plurality of low-voltage inverters 2, wherein the plurality of low-voltage inverters 2 in turn each supply a low supply ac voltage uv1 to the low-voltage actuators 4. Likewise, the extra-low voltage dc voltage Uz from the dc voltage converter 3 may be supplied to a plurality of extra-low voltage inverters 5, wherein the plurality of extra-low voltage inverters 5 in turn each supply a low supply ac voltage uv1 to the extra-low voltage actuators 6. Such a power supply system 1 is schematically shown in fig. 4.

The low-voltage inverter 2 and/or the extra-low-voltage inverter 5 are preferably designed to be bidirectional, wherein the rectifier 8 can also be designed to be bidirectional. However, it is particularly preferred that the dc voltage converter 3 is implemented bidirectional and/or isolated (insulated). Excess energy from the extra-low voltage actuator 6 can thus be fed back into the supply network via the extra-low voltage inverter 5 and further via the dc voltage converter 3. However, the excess energy from the extra-low voltage actuator 6 can also be fed to the low voltage actuator 4 via the extra-low voltage inverter 5, the dc voltage converter 3 and further via the low voltage inverter 2. Of course, the excess energy from the low-voltage actuator 4 can also be fed via the low-voltage inverter 2, the dc converter 3 and the extra-low-voltage inverter 5 into the extra-low-voltage actuator 4 or fed back from the low-voltage actuator 4 via the low-voltage inverter 2 and the rectifier 8 into the supply network, if the rectifier 8 is likewise designed to be bidirectional.

Preferably, the dc voltage converter 3 comprises an inverter unit 30 for converting the low input dc voltage into a primary voltage ue1 (and vice versa); a transformer unit 3 connected to the inverter unit 30 for transforming the primary ac voltage ue1 into a secondary ac voltage ue2 (and vice versa); and a rectifier unit 32 connected to the transformer unit 31 for converting the secondary alternating voltage ue2 into an ultra low direct voltage uz (and vice versa).

Fig. 5 shows a particularly advantageous design of the dc voltage converter 3. In this case, the inverter unit 30 is advantageously embodied as a dc voltage/ac voltage bridge and comprises a first primary-side bridge branch having a first primary-side power switch S11 and a third primary-side power switch S13 connected in series. The dc voltage/ac voltage bridge further includes a second primary side bridge leg having a second primary side power switch S12 and a fourth primary side power switch S14 connected in series. The first primary side bridge limb and the second primary side bridge limb are each connected in parallel to the low input direct voltage Ue. A diode is connected in parallel to all primary-side power switches S11, S12, S13, S14, which diode is forward-biased with respect to the low input dc voltage Ue. The primary-side power switches S11, S12, S13, S14 are controlled by a primary-side control unit (not shown) such that the primary alternating voltage ue1 is accessible between the connection point of the first primary-side power switch S11 and the third primary-side power switch S13 and the connection point of the second primary-side power switch S12 and the fourth primary-side power switch S14.

The primary alternating voltage u1 is applied to the primary winding L1 of the transformer unit 31. Also shown in fig. 5 is a leakage inductance Ls in series with the primary winding. The transformer unit 31 converts the primary ac voltage ue1 into the secondary ac voltage ue2 according to a conversion ratio N1: N2.

Furthermore, the rectifier unit 32 is advantageously embodied as an alternating voltage/direct voltage bridge. The ac/dc bridge comprises a further first secondary bridge branch having a first secondary power switch S21 and a series-connected third secondary power switch S23. The ac/dc voltage bridge also includes a second secondary bridge branch connected in parallel with the first secondary bridge branch and having a second secondary power switch S22 and a fourth secondary power switch S24 connected in series. The secondary ac voltage ue2 of the transformer unit 31 is (applied) between the connection point of the first secondary power switch S21 and the third secondary power switch S23 and the connection point of the second secondary power switch S22 and the fourth secondary power switch S24. The secondary power switches S21, S22, S23, S24 are controlled by a secondary control unit (not shown) such that the secondary alternating voltage ue2 is converted into an ultra-low direct voltage Uz, which is connected in parallel to the first secondary bridge branch and the second secondary bridge branch. Of course, the primary control unit and the secondary control unit may be integral components of the dc voltage converter control unit. For all secondary power switches S21, S22, S23, S24, a diode is connected in parallel, which diode is forward-biased with respect to the very low dc voltage Uz.

The dc voltage converter 3 shown is implemented bidirectionally, i.e. it is possible to convert a low input dc voltage Ue into an extra low dc voltage Uz and vice versa. Therefore, power is supplied from the output side to the input side of the dc voltage converter 3 and vice versa. The rectifier unit 32 also serves as an inverter unit if the extra low direct voltage Uz is converted into a low input direct voltage Ue, i.e. in the embodiment shown, an alternating voltage/direct voltage bridge also serves as a direct voltage/alternating voltage bridge. Likewise, the inverter unit 30 also serves as a rectifier unit, i.e. in the embodiment shown, a direct voltage/alternating voltage bridge also serves as an alternating voltage/direct voltage bridge.

The isolation transformer unit 31 is used to isolate the input side of the dc voltage converter 3 from the output side of the dc voltage converter 3.

Furthermore, the dc voltage converter 3 has an optional input capacitor C1 connected in parallel with the low input dc voltage Ue_{Input device}、C2_{Input device}And an optional output capacitor C connected in parallel with the ultra-low DC voltage Uz_{Output of}. Also provided with optional, series-connected input filter inductors Lx_{Input device}And optionally a parallel input filter capacitance Cx_{Input device}. In addition, an optional, series-connected output filter inductance Lx is shown_{Output of}And an optional, parallel output filter capacitance Cx_{Output of}。

In order to be available for low input dc voltages Ue up to 900V, primary power switches S11, S12, S13, S14 with blocking capability up to 1200V may be used. In order to achieve high efficiency, silicon carbide is preferably used as the semiconductor material of the primary power switches S11, S12, S13, S14.