DE102017010390A1 - energy converters - Google Patents

Abstract

The invention relates to energy converters (50, 60, 62, 64) for electrically coupling a first on-board network (12) acted upon by a first direct electrical voltage (U) to a second electrical on-board network (14) acted upon by a second direct electrical voltage (U) The energy converter (50, 60, 62, 64) comprises a first series circuit (52) of three series-connected switching elements (32, 34, 36), wherein the first series circuit (52) for connecting to the first or the second of the vehicle electrical system (12, 14), the series circuit (52) having two connection points of two respective ones of the switching elements (32, 34, 36) at which the respective switching elements (32, 34, 36) are electrically coupled to each other the connection points by means of a respective electrical inductance (30, 40) to the other of the two electrical systems (12, 14) is connected.

Description

The invention relates to an energy converter for electrically coupling a first electrical system supplied with a first electrical DC voltage to a second electric vehicle electrical system charged with a second electrical DC voltage.

Generic energy converters find particular use when at least two electrical systems, such as the first and the second electrical system, which are acted upon by different electrical DC voltages to be electrically coupled together. As part of the electrical coupling electrical energy between the two electrical systems can be exchanged by the energy converter in a predeterminable manner. Such electrical energy converters are now finding particular use in motor vehicles, in particular in motor vehicles which are designed to be electrically driven. Generic energy converters can be designed for unidirectional or bidirectional energy coupling. In order to realize the energy coupling, the energy converter is usually designed as a clocked energy converter. By means of the clocked energy converter, the desired electrical coupling function can be provided. For this purpose, the clocked energy converter can be controlled in a suitable manner by means of a control unit.

Electric vehicle electrical systems as well as motor vehicles with such on-board networks are basically well-known in the prior art. For example, the WO 2013/010 693 A1 a system with a battery charger and a vehicle power supply stage. Motor vehicles, in particular, electrically driven motor vehicles generally have at least one electrical system which comprises electrical devices and units. The electrical system serves to electrically couple the electrical devices and units with each other in a predeterminable manner. At least a part of the electrical devices or units is connected to the electrical system. The electrical system thus serves to distribute the electrical energy within the motor vehicle.

In particular, in the case of electrically driven motor vehicles, at least a second electrical system is generally provided, wherein at least one of the two electrical systems is designed to be exposed to a DC voltage in the high-voltage range. The term "high voltage" includes a DC electrical voltage that is greater than about 60V. Preferably, the term "high voltage" conforms to the standard ECE R 100.

Meanwhile, it is increasingly the case of electrically driven vehicles that the first and the second electrical system are designed for high voltage, but for different DC voltages in the high voltage range. Thus, for example, the first electrical system can be acted upon by a DC voltage of about 800 V, whereas the second electrical system can be supplied with a DC voltage of about 400 V. Of course, the values of the DC voltages can also be chosen differently. In principle, however, the aforementioned voltage values result in consideration of standardized components, as well as electrical devices which are designed or standardized for such electrical voltages.

In order to be able to electrically couple the two electrical vehicle electrical systems with one another, it is customary in the prior art to couple the two electric vehicle electrical systems electrically to each other electrically. For reasons of electrical safety, a galvanic connection between these two on-board networks, in particular in the area of high voltage, as a rule not desired, or in part also not allowed. In addition, in the case of on-board networks which are designed for high-voltage and, moreover, are generally electrically insulated from an electrical reference potential, for example a vehicle mass of the motor vehicle or the like, the function of an insulation monitor may be impaired. This can be caused by an asymmetry of the electrical potentials of the first and the second DC voltage with respect to the electrical reference potential. The coupling of the two electrical systems therefore takes place in the prior art usually by means of a galvanically isolated DC / DC converter as a clocked energy converter. Such a galvanically isolated DC / DC converter is large, expensive, heavy and allows only a limited efficiency because of the provision of electrical insulation. In addition, two separate insulation monitors are required to monitor the two vehicle electrical systems, especially when used in the high voltage range.

If the two vehicle electrical systems were galvanically coupled to one another, the asymmetric electrical potentials of the two vehicle electrical systems could arise in relation to the electrical reference potential due to the DC / DC converter being connected to the two vehicle electrical systems. This can lead to equalizing currents, for example in a potential equalization line or in corresponding high-voltage shielding. If an electrical conductivity is insufficiently available in this regard, dangerous voltages can arise at undesired locations, for example at a converter housing of the DC / DC converter. Out However, for reasons of electrical safety, such a case must not lead to a risk to a user or the motor vehicle.

In addition, it should be borne in mind that when connecting two vehicle electrical systems with different DC voltages, further problems may arise which may arise because the two vehicle electrical systems are designed differently with regard to electrical insulation, in particular with regard to creepage distances and clearances. The interpretation of the creepage distances and clearances of each of the vehicle electrical system is usually based on the respective DC voltage with which the respective vehicle electrical system is acted upon. In the case of an insulation fault in that of the vehicle electrical system, which is acted upon by the higher DC voltages, therefore, the electrical insulation of that of the vehicle electrical system, which is acted upon by the smaller DC voltages, can be overloaded with a galvanic coupling. This can not only cause damage but even destruction. As a result, there is the danger that the second of the vehicle electrical system is also damaged due to the disturbance of the electrical insulation of the first of the vehicle electrical system.

The invention is therefore based on the object to improve an energy coupling between on-board networks, in particular in electrically driven motor vehicles.

With the invention, an energy converter according to the independent claim 1 is proposed.

Advantageous developments emerge by features of the dependent claims.

With respect to a generic energy converter is particularly proposed by the invention that this has a first series connection of three series-connected switching elements, wherein the first series circuit is formed for connection to the first or the second of the vehicle electrical system, wherein the series connection two connection points of two respective Having switching elements at which the respective switching elements are electrically coupled together, wherein a respective one of the connection points is connected by means of a respective electrical inductance to the other of the two vehicle electrical system.

The invention is based on the idea that a galvanic coupling between the first and the second electrical system can be realized by the two inductors in conjunction with the at least one series circuit of three switching elements, which due to the nature of the coupling special security requirements can be realized by means which in particular the aforementioned problems in terms of electrical safety can be solved. It is thus - contrary to the prior art - possible with the invention, the first and the second electrical system to electrically couple with each other, and at the same time to ensure high reliability and electrical safety.

Namely, with the invention, it is possible to compensate for the asymmetry with respect to the electrical reference potential which is generally produced in the case of a galvanic coupling of the two electrical vehicle systems due to the different DC voltages. This can be achieved by the interaction of the switching elements with the inductors, so that by means of the energy converter according to the invention, the electrical potentials of the first and the second electrical system can be set almost floating against each other. This makes it possible to realize a balance in relation to the reference potential between the electrical potentials of the first and the second electrical system. This has a particularly advantageous effect in measures for producing the electromagnetic compatibility, in particular a radio interference suppression. The invention is therefore particularly suitable for use in on-board networks whose DC voltage is electrically isolated from the reference potential, such as IT networks or the like.

In addition, the invention allows the occurrence of a fault in one of the two electric vehicle electrical systems by means of the energy converter according to the invention, a decoupling or deactivation of the electrical coupling can be achieved so that the disturbance can not affect the respective other of the electrical system. As a result, in particular the electrical safety, especially the protection of persons, can be improved. Finally, it can be further achieved with the invention that the electrical insulation of both vehicle electrical systems, namely the first and the second electrical vehicle electrical system, can be monitored only with a single insulation monitor.

With the invention can be achieved in particular that none of the electrical potentials of the DC voltages of the first and the second electrical system must be selected together. Rather, the invention allows due to the circuit structure to electrically decouple the electrical potentials of the DC voltage of the first electrical system from the electrical potentials of the DC voltage of the second electrical system. With the circuit structure according to the invention, a corresponding adaptation can be achieved in a single converter stage of the clocked energy converter.

The use of the energy converter proves to be particularly advantageous if the first series connection is connected to that of the on-board electrical system which has the larger one of the direct voltages. Thus, from the second electrical system, an energy conversion to the first electrical system can be realized by the energy converter realizes a Hochsetzstellfunktion. Conversely, an energy flow is possible by the energy converter realizes a Tiefsetzstellfunktion. Is only an energy conversion in a single direction required, for example, from the first electrical system exclusively to the second electrical system or vice versa, the energy converter can be simplified accordingly, for example, by switching elements are realized only by diodes. As a result, the circuit complexity can be further reduced. If, however, a bi-directional coupling of the first and the second on-board network at any voltage levels of the DC voltages of the two vehicle electrical system required, a second series circuit of three series-connected switching elements is preferably provided, wherein the second series circuit is designed for connection to the respective other of the vehicle electrical system, wherein the series connection also has two connection points each of two respective ones of the switching elements, at which the respective switching elements are electrically coupled to each other, wherein a respective one of the connection points of the first series connection is connected by means of the respective electrical inductance to a respective connection point of the second series circuit. By means of this circuit structure in the manner of a modified H-bridge circuit, it is thus possible to realize a high level of flexibility with regard to energy conversion with little effort and without the requirement of galvanic isolation.

With the energy converter according to the invention, it is thus possible to achieve a symmetrization of the electrical potentials of the DC voltages of the first and the second electrical system with respect to the electrical reference potential. It is also possible by the energy converter of the invention to achieve a substantially higher power density, a lower weight and also lower costs and a higher efficiency compared to DC / DC converters of the prior art, which are designed as galvanically insulating converters.

Furthermore, the invention allows to monitor both electrical systems with only a single insulation guard. Compensation currents on potential cables as well as on shieldings can be reduced if not largely avoided. At the same time an increase in the safety of Berührschutzes is possible by an insufficient connection of the equipotential bonding conductor can no longer generate dangerous electrical voltage to a converter housing of the energy converter. In addition, a higher reliability against the DC / DC converter of the prior art can be achieved. Furthermore, it can be achieved that, in the event of an insulation fault in one of the two vehicle electrical systems, the other of the two vehicle electrical systems need not be substantially impaired thereby. The insulation error can therefore be limited to the respective vehicle electrical system. In addition, in the case of an insulation fault by adjusting the electrical potentials by means of the energy converter still the other of the electrical system can be operated without the risk of overloading the local insulation needs to be taken into account. Finally, a guarantee of safety, in particular a high-voltage safety, can be achieved with respect to an insulation fault in that of the vehicle electrical system with the larger of the DC voltages.

It proves to be particularly advantageous if the electrical potentials of the first and the second electrical DC voltage are adjusted symmetrically to a common electrical reference potential. This makes it possible to set the electrical potentials of the first and the second DC electrical voltage so that with respect to the electrical reference potential is given a symmetrical adjustment. This is advantageous in particular for electrical safety as well as for measures in the field of electromagnetic compatibility, in particular radio interference suppression, for example in relation to Y capacitors or the like.

Furthermore, it proves to be advantageous if the electrical inductances essentially have approximately the same inductance value. This allows a particularly uniform load of the clocked energy converter can be achieved.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing (s). The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

• 1 ein schematisches Prinzipschaltbild für einen galvanisch gekoppelten bidirektionalen Energiewandler gemäß der Erfindung, der für den Einsatz bei unterschiedlichen Spannungslagen von angeschlossenen Bordnetzen ausgebildet ist;
• 2 ein schematisches Spannungs-Orts-Diagramm für den Energiewandler gemäß 1,
• 3 eine schematische Tabelle für Schaltmuster der Schaltelemente des Energiewandlers gemäß 1,
• 4 ein schematisches Prinzipschaltbild für einen galvanisch gekoppelten Energiewandler basierend auf 1, wobei der Energiewandler für einen unidirektionalen Tiefsetzbetrieb ausgebildet ist,
• 5 ein schematisches Prinzipschaltbild für einen galvanisch gekoppelten Energiewandler basierend auf 1, wobei der Energiewandler für einen unidirektionalen Hochsetzbetrieb ausgebildet ist,
• 6 ein schematisches Prinzipschaltbild für einen galvanisch gekoppelten bidirektionalen Energiewandler basierend auf 1, wobei der Energiewandler für einen unidirektionalen Tiefsetzbetrieb und für einen unidirektionalen Hochsetzbetrieb ausgebildet ist,
• 7 ein schematisches Simulationsschaltbild für eine Simulation des Energiewandlers gemäß 1,
• 8 bis 13 schematische Diagrammdarstellungen von Simulationsergebnissen der Simulation gemäß 7,
• 14 ein schematisches Simulationsschaltbild einer Simulation wie 7 für den Energiewandler gemäß 6,
• 15 bis 20 schematische Diagrammdarstellungen von Simulationsergebnissen gemäß den 8 bis 13 zur Simulation gemäß 14,
• 21 ein schematisches Prinzipschaltbild für eine galvanisch getrennten bidirektionalen Energiewandler gemäß dem Stand der Technik, der für einen Einsatz bei unterschiedlichen Spannungslagen von angeschlossenen Bordnetzen ausgebildet ist,
• 22 ein schematisches Spannungs-Orts-Diagramm für den Energiewandler gemäß 21, welches elektrische Potentiale in Bezug auf eine Fahrzeugmasse darstellt,
• 23 eine schematische Schaltbilddarstellung wie 1 mit einem Isolationsfehler,
• 24 bis 29 schematische Diagrammdarstellungen zu Auswirkungen des Isolationsfehlers gemäß 23 gemäß den 8 bis 13,
• 30 eine schematische Schaltbilddarstellung wie 23, wobei ein Schaltelement des Energiewandlers dauerhaft eingeschaltet wird,
• 31 bis 36 schematische Diagrammdarstellungen der Auswirkung gemäß 30, wobei keine Veränderung des Schaltverhaltens der Schaltelemente vorgenommen wird, und
• 37 bis 42 schematische Diagrammdarstellungen wie 31 bis 36, wobei das Schaltverhalten der Schaltelemente verändert wird,

Showing:

• 1 a schematic block diagram for a galvanically coupled bidirectional energy converter according to the invention, which is designed for use in different voltage levels of connected on-board networks;
• 2 a schematic voltage-local diagram for the energy converter according to 1 .
• 3 a schematic table for switching pattern of the switching elements of the energy converter according to 1 .
• 4 a schematic block diagram for a galvanically coupled energy converter based on 1 wherein the energy converter is designed for a unidirectional step-down operation,
• 5 a schematic block diagram for a galvanically coupled energy converter based on 1 wherein the energy converter is designed for a unidirectional boosting operation,
• 6 a schematic block diagram for a galvanically coupled bidirectional energy converter based on 1 wherein the energy converter is designed for a unidirectional step-down operation and for a unidirectional step-up operation,
• 7 a schematic simulation diagram for a simulation of the energy converter according to 1 .
• 8th to 13 schematic diagrams of simulation results of the simulation according to 7 .
• 14 a schematic simulation diagram of a simulation such 7 for the energy converter according to 6 .
• 15 to 20 schematic diagrams of simulation results according to the 8th to 13 according to the simulation 14 .
• 21 a schematic block diagram for a galvanically isolated bidirectional energy converter according to the prior art, which is designed for use in different voltage levels of connected on-board networks,
• 22 a schematic voltage-local diagram for the energy converter according to 21 representing electrical potentials with respect to a vehicle mass,
• 23 a schematic diagram representation as 1 with an insulation fault,
• 24 to 29 Schematic diagram of the effects of the insulation fault according to 23 according to the 8th to 13 .
• 30 a schematic diagram representation as 23 wherein a switching element of the energy converter is switched on permanently,
• 31 to 36 schematic diagram of the effect according to 30 , wherein no change in the switching behavior of the switching elements is made, and
• 37 to 42 schematic diagram representations like 31 to 36 , wherein the switching behavior of the switching elements is changed,

21 shows an energy converter 10 According to the prior art, for coupling a first electrical system voltage U ₁ acted upon first electrical system 12 with an acted upon by a second electrical DC voltage U ₂ second electrical system 14 serves. The energy converter 10 has a clocked converter unit 16 and, in the present case, is a bi-directional energy converter that provides both a boost and a boost function.

For this purpose, the clocked energy converter includes 10 four semiconductor switches 32 . 34 , 36, 38, which are formed in the present case by metal oxide semiconductor field effect transistors (MOSFET), which are connected in the manner of an H-bridge circuit. The H-bridge circuit further includes an inductance 30 that serves the energy conversion. The clocked energy converter 10 is basically a known circuit topology, which is why reference is made to statements relating to the functionality of this circuit on the relevant state of the art.

The energy converter 10 is in a metal case 18 arranged, which is electrically conductive with a vehicle mass 20 a not shown electrically driven motor vehicle, in this case an electric vehicle, is connected. With one connection is the clocked converter unit 16 to the first electrical system 12 and with a second connection to the second electrical system 14 connected. The first and the second electrical DC voltage U ₁ , U ₂ are different. In the present embodiment it is provided that the electrical dc voltage U ₁ is about 800 V, whereas the direct electric voltage U ₂ is about 400 volts. Connection side includes the energy converter 10 respective backup capacitors 26 . 28 ,

With the clocked converter unit 16 can thus by suitable clock patterns for the semiconductor switches 32 . 34 . 36 . 38 a given energy conversion can be achieved. For this purpose, the semiconductor switches 32 . 34 . 36 . 38 controlled by a control unit, not shown in a suitable manner in clock mode.

For the purpose of radio interference suppression Y-capacitors 22 are provided, each of the electrical potentials HV ₁ +, HV- and HV ₂ + in the region of the connection to the respective vehicle electrical system 12 . 14 via a respective one of the Y capacitors 22 to the housing 18 is coupled. Parallel to each of the Y capacitors 22 is by means of an electrical resistance 24 a respective insulation resistance shown.

As 21 shows is in galvanically coupled energy converters, such as the energy converter 10 , which is designed in the present case as a DC / DC converter, one of the electrical potentials used, here HV-, looped directly from one of the electrical system connections to the other of the electrical system connections. The respective voltage adjustment thus relates only to the corresponding high-voltage potentials HV + of the first and second DC electrical voltages U ₁ , U ₂ . For reasons of electrical safety, all high-voltage potentials of low-voltage potentials, in particular of the vehicle ground, are at least in the case of electrically driven motor vehicles 20 , electrically isolated or isolated. An electrical connection therefore consists only of the Y capacitors 22 and the electrical resistors 24 that represent the insulation resistances.

By the Y-capacitors 22 and the electrical resistors 24 is the electrical potential of the vehicle mass 20 in a high-voltage system, it is normally essentially between the two high-voltage potentials HV and HV +. In a galvanically coupled energy converter, such as the energy converter 10 according to 21 However, there is an asymmetry within the vehicle mass 20 generated. This can lead to the Y capacitors 22 charging unevenly, insulation monitoring being disturbed, and in the least favorable case, even different ground potentials within the vehicle ground 20 can result. As a result, high electrical voltages between different electrical devices, such as their housings or the like may be present, whereby, for example, a permanent electric current, for example via a potential equalization line or shielding, in particular of lines acted upon by high voltage, can be effected. 22 shows an example of the energy converter 10 according to 21 how the different electrical potentials can be set for a well-connected potential equalization line.

1 now shows an energy converter 50 according to the invention, with which the aforementioned problems can be avoided. The energy converter 50 serves the galvanic electrical coupling of the first electrical system voltage U ₁ acted upon first vehicle electrical system 12 with the second electrical DC voltage U ₂ second electric vehicle electrical system 14 , For this purpose, the energy converter includes 50 a first series circuit 52 of three series-connected switching elements 32 . 34 . 36 , The first series circuit 52 serves to connect to the first electrical system 12 , The first series circuit 52 has two connection points of two respective ones of the switching elements 32 . 34 . 36 on, where the respective switching elements 32 , 34, 36 are electrically coupled together. A respective one of the connection points is by means of a respective electrical inductance 30 . 40 to the second electrical system 14 connected.

For connection to the second electrical system 14 includes the energy converter 50 a second series circuit 54 of three series-connected switching elements 38 . 42 . 44 , The second series circuit 54 serves to connect to the second electrical system 14 , The second series circuit 54 also has two connection points of two respective ones of the switching elements 38 . 42 . 44 on, where the respective switching elements 38 . 42 . 44 are electrically coupled together. A respective one of the junctions of the first series circuit 52 is by means of the respective electrical inductance 30 . 40 connected to a respective connection point of the second series circuit 54.

The other elements with respect to the Y capacitors 22, the electrical resistors 24, the housing 18 as well as the vehicle mass 20 and the electrical system 12 . 14 correspond to what is already based on 21 previously explained why reference is made in this respect to the corresponding statements.

The energy converter 50 according to 1 is configured to electrically couple the first and the second electrical system 12, 14 bidirectionally. In addition, the energy converter 50 according to 1 designed to be operated in each of the coupling directions both as a boost converter and as a buck converter. This can be achieved by the control unit, not shown, which the switching elements 32 . 34 . 36 . 38 . 42 . 44 of the energy converter 50 operated in a corresponding manner in clock mode.

Due to the special structure of the energy converter 50 does not need any of the electrical potentials of the first and the second electrical system 12 . 14 through the energy converter 50 to be dragged through. At this point, the circuit topology therefore differs significantly from that described in relation to the prior art 21 was explained. This allows the energy converter 50 namely the HV- potentials are set almost independently. In the in 1 illustrated circuit topology is realized by appropriate clocking of the switching elements 32, 34, 36, 38, 42, 44, the corresponding setting of the electrical potential HV.

The switching elements 32 . 34 . 36 . 38 . 42 . 44 are formed in this embodiment as a semiconductor switch. The semiconductor switches are designed here as metal oxide semiconductor field effect transistors (MOSFET). In alternative embodiments, other transistors, in particular bipolar transistors such as insulated gate bipolar transistor (IGBT) can also be used here. The semiconductor switches are presently formed by transistors which are operated in the switching mode. For this purpose, they receive appropriate control signals from the control unit.

The effects on the potential course by the energy converter 50 through, are based on 2 shown schematically. Out 2 it can be seen that in the energy converter 50 according to 1 Ground covers on the connection sides to the on-board networks 12 . 14 correspond to substantially the same electrical potential. An influence due to an asymmetry in the vehicle mass 20 with respect to the high-voltage potentials within the energy converter 50 can be kept very small, especially negligible, in particular by the Y-capacitors 22 to the housing 18 can be significantly reduced and by the insulation resistance 24 inside the case 18 can be kept much larger than at the terminals. This can be achieved, for example, by greater distances from live parts of the energy converter 50 to the housing 18 ,

3 schematically shows a table for the operation of the switching elements 32 . 34 . 36 . 38 , 42, 44 to realize a respective energy conversion function. A "0" stands for an open switching element, in which a current flow at most by an inverse diode of the respective switching elements 32 . 34 . 36 . 38 . 42 . 44 flows. A "1" stands for a closed switching element, which is permanently switched on for the intended conversion operation. "T" stands for a switching element which is operated by the control unit in the cyclic operation or switching operation.

By changing a clock ratio, the desired conversion functionality can be achieved. "0/1" indicates that the setting of this switching element can be made independently for the desired functionality. It can be provided that, when the inverse diode is acted upon by an electric current, the respective switching element is switched on at the same time in order to be able to reduce, for example, forward losses.

4 shows another energy converter 60 according to the invention, its circuit topology on that of the energy converter 50 which is why reference is additionally made to the relevant remarks. The energy converter 60 In the present case, it is designed only for unidirectional operation, and at the same time it is designed as a step-down converter. The energy converter 60 according to 4 therefore allows only electrical energy from the first electrical system 12 to the second electrical system 14 to promote. As a result, the circuit structure and the wiring effort of the energy converter 60 towards the energy converter 50 be significantly reduced. The reduction relates in particular to the switching elements required for the corresponding conversion operation, wherein the second series circuit 54 can be completely saved and in the first series circuit 52 the switching element 34 is replaced by a diode D1.

Another energy converter 62 in place of a buck-boost operation like the energy converter 60 provides a Hochsetzstellbetrieb is based on 5 shown. The difference to the embodiment according to 1 is essentially in the series circuits, with respect to the energy converter 50 according to 1 the first series circuit 52 is omitted and in the second series circuit 54, the switching elements 38 and 44 are replaced by diodes D2, D3. As well as this energy converter 62 is designed only for a unidirectional conversion operation, a very simple circuit structure can also be achieved here, so that the energy converter 62 - as well as the energy converter 60 - Can be made very compact in terms of effort.

6 shows a further embodiment of an energy converter 64 who is on the design of the energy converter 50 according to 1 which is why reference is additionally made to the relevant remarks. The energy converter 64 is different from the energy converter 50 in that only the first series circuit 52 is present. The second series circuit 54, however, is omitted. The inductors 30 . 40 thus immediately make the connections for the second electrical system 14 ready. The energy converter 64 is different from the energy converter 50 in that the energy converter 64 a unidirectional Tiefsetzstellfunktion of the first electrical system 12 to the second electrical system 14 provides. In addition, the energy converter 64 at the same time a unidirectional boosting function for an energy transfer from the second electrical system 14 to the first electrical system 12 ready. The energy converter 64 is therefore preferably used when the first DC voltage U _{1 is} greater than the second DC voltage U ₂ . This can be taken for a variety of high-voltage electrical systems as given. For such applications, therefore, the energy converter does not need as much effort as the energy converter 50 according to 1 to be designed.

7 shows a schematic representation of a simulation circuit diagram of the energy converter 50 for the simulation by means of a suitable simulation tool. The results are based on the 8th to 13 shown. The 8th to 13 show schematic diagrams of the effect of the energy converter 50 according to 1 ,

8th shows a schematic diagram of a voltage waveform of the first DC voltage U ₁ with a graph 74 , An abscissa 70 is assigned to the time in seconds, whereas an ordinate 72 associated with the electrical voltage in volts. It can be seen that a substantially constant DC voltage of about 800 V is established.

9 shows in a comparable schematic diagram as 8th with a graph 76 a voltage curve of the second DC voltage U ₂ . The abscissa 70 and the ordinate 72 are as appropriate 8th selected. It can be seen that a substantially constant DC voltage of about 400 V is established.

The 10 to 13 show in further schematic diagrams like the 8th and 9 Voltage curves, as they relate to the various high-voltage potentials of the first and the second electrical system 12 . 14 opposite the vehicle mass 20 to adjust.

10 shows by means of a graph 80 an electrical voltage between the electrical potential HV ₁ + of the first electrical system 12 and the vehicle mass 20 , It can be seen that an electrical voltage of about 400 V is established. 11 shows a corresponding representation of the electrical potential HV ₁ -, wherein by means of the graph 82 it can be seen that a corresponding DC voltage of about -400 V is established.

The 12 and 13 provide the appropriate situation for the second electrical system 14 where by means of a graph 84 in 12 the electrical voltage of the electrical potential HV ₂ + is shown in relation to the vehicle mass and by means of a graph 86 in 13 the electrical voltage between the electrical potential HV _{2 to} the vehicle ground 20 is shown. It can be seen that in 12 a voltage of about +200 V, whereas in 13 a voltage of about -200 V is established by means of the graph 86.

14 shows a schematic representation of a simulation circuit diagram, such as 7 for the energy converter 60 according to 4 , The 15 to 20 show corresponding representations like the 8th to 13 , Graphs 87, 88, 90, 92, 94, 96 show the corresponding voltage curves in the respective diagrams. Basically, the conditions are as they have already been explained with respect to the previous embodiment, which is why reference is additionally made to the relevant explanations.

23 shows in a further schematic circuit diagram representation of the energy converter 50 according to 1 , where now an insulation fault 58 as a disturbance between the electrical potential HV ₁ + and the vehicle ground 20 over the housing 18 is made. The energy converter 50 is operated here in Tiefsetzstellbetrieb. As the electrical potentials but through the energy converter 50 are electrically isolated from each other, the high potential is not automatically in the designed for low voltages second electrical system 14 at. By properly controlling the energy converter 50 This can be achieved.

Add a voltage measurement between the high-voltage potentials and the vehicle mass 20 What, for example, in the energy converter itself or in any other component in a vehicle electrical system 12 . 14 can be provided, the energy converter 50 Recognize the shifted voltages and adjust its regulation so that in a wiring system with the lower voltage, here the electrical system 14 , no dangerous electrical potential arises. In Tiefsetzstellbetrieb shown here, only the switching element, at the electrical potential of the error occurs to be permanently switched through. In the present case, this is the switching element 32 , Without the duty cycle on the switching element 36 to change, the output voltage remains constant at the desired value and the second electrical system 14 can continue to operate. However, the electrical potentials are no longer symmetrical to the vehicle mass after this procedure 20 ,

A corresponding representation with respect to the insulation error, as he just using 23 has been explained with the schematic diagrams according to the 24 to 29 shown schematically. The diagrams correspond to those already explained above. By means of the graphs 98 . 100 . 102 . 104 . 106 . 108 the corresponding voltage curves are shown. It can be seen that at time t = 0.5 s the insulation fault 58 occurs. Accordingly, the voltage curves set.

30 shows a representation like 23 , but now the insulation fault 58 occurs during boosting operation. This case is less critical because the second wiring system 14 in this case designed for the larger DC voltage. Will the switching element 44 permanently switched on, the system can be stabilized better overall. The corresponding simulations show the 31 to 36 , where also the disturbance 58 occurs at the time t = 0.5 s. By means of the graphs 110, 112, 114, 116, 118, 120 shown in the diagrams, the corresponding voltage changes can be understood.

The voltage curves adjust without the control unit changing the switching behavior of the switching elements 32 . 34 . 36 . 38 . 42 . 44 needs to change. The 37 to 42 show according to the 31 to 36 schematic diagrams, wherein the control unit makes a change in the switching behavior here, in particular with respect to the switching of the switching element 44 , It can be seen that the electrical potentials of the second electrical system 14 essentially symmetrical with respect to the vehicle mass 20 stay. Using the graphs shown in the diagrams 122 . 124 . 126 . 128 . 130 . 132 the corresponding voltage changes can be reconstructed.

The embodiments are merely illustrative of the invention and are not intended to limit this.

LIST OF REFERENCE NUMBERS

10

energy converters

12

first electrical system

14

second electrical system

16

converter unit

18

casing

20

vehicle mass

22

Y-capacitor

24

resistance

26

backup capacitor

28

backup capacitor

30

inductance

32

Semiconductor switches

34

Semiconductor switches

36

Semiconductor switches

38

Semiconductor switches

40

inductance

42

Semiconductor switches

44

Semiconductor switches

50

energy converters

58

insulation fault

60

energy converters

62

energy converters

64

energy converters

70

abscissa

72

ordinate

74

graph

76

graph

78

graph

80

graph

82

graph

84

graph

86

graph

88

graph

90

graph

92

graph

94

graph

96

graph

98

graph

100

graph

102

graph

104

graph

106

graph

108

graph

110

graph

112

graph

114

graph

116

graph

118

graph

120

graph

122

graph

124

graph

126

graph

128

graph

130

graph

132

graph

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2013/010693 A1 [0003]

Claims (6)

Energy converter (50, 60, 62, 64) for electrically coupling a first on-board network (12) acted upon by a first direct electrical voltage (U ₁ ) to a second electrical vehicle electrical system (14) acted upon by a second direct electrical voltage (U ₂ ), characterized by a first series circuit (52) of three series-connected switching elements (32, 34, 36), the first series circuit (52) being designed for connection to the first or second of the vehicle electrical system (12, 14), the series circuit (52 ) has two connection points of two respective ones of the switching elements (32, 34, 36), at which the respective switching elements (32, 34, 36) are electrically coupled to each other, wherein a respective one of the connection points by means of a respective electrical inductance (30, 40) the other of the two electrical systems (12, 14) is connected. Energy converter (50) after Claim 1 characterized in that at least one of the switching elements (32, 34, 36) is formed by a diode (D1, D2, D3) to form the energy converter (60, 62, 64) for unidirectional energy conversion. Energy converter (50) after Claim 1 or 2 characterized by a second series connection (54) of three series-connected switching elements (38, 42, 44), the second series circuit (54) being designed for connection to the respective other of the vehicle electrical system (12, 14), the series circuit ( 54) also has two connection points (38, 42, 44) of two respective ones of the switching elements (38, 42, 44) at which the respective switching elements (38, 42, 44) are electrically coupled together, wherein a respective one of the connection points of the first Series circuit (52) is connected by means of the respective electrical inductance (30, 40) to a respective connection point of the second series circuit (54). Energy converter according to one of the preceding claims, characterized in that the electrical inductances (30, 40) have the same inductance value. Energy converter after Claim 1 , characterized in that the first and the second electrical system (12, 14) by means of the energy converter (50, 60, 62, 64) are galvanically coupled. Energy converter according to one of the preceding claims, characterized in that the energy converter (50, 60, 62, 64) is formed, electrical potentials (HV ₁ , HV ₂ ) of the first and the second DC electrical voltage (U ₁ , U ₂ ) symmetrically to to set a common reference potential (20).

Images