Vehicle electrical system arrangement and method for precharging a high-voltage vehicle electrical system

Abstract

The invention relates to a method for precharging a high-voltage electrical system (3) of an electrical system arrangement (1) of an electrically driven vehicle (20), wherein the electrical system arrangement (1) has at least one high-voltage battery (2), a high-voltage electrical system (3) and at least one low-voltage electrical system (4, 11), wherein the high-voltage electrical system (3) and the high-voltage battery (2) can be selectively connected to or separated from one another by at least one main contactor (5), wherein a first DC / DC converter (6) is connected with a high-voltage side to the high-voltage electrical system (3) and with a low-voltage side to a first low-voltage electrical system (4), wherein a second DC / DC converter (7) is connected with a high-voltage side to the high-voltage battery (2) and with a low-voltage side can be connected to or separated from the first low-voltage electrical system (4) via a coupling element (8), wherein the second DC / DC converter (7) is configured toto convert a high-voltage voltage of the high-voltage battery (2) into a low-voltage voltage on its low-voltage side, wherein, for pre-charging the high-voltage vehicle electrical system (3), the coupling element (8) is closed with the main contactor (5) open, the high-voltage voltage from the high-voltage battery (2) is converted into a low-voltage voltage by the second DC / DC converter (7), and the low-voltage voltage applied via the coupling element (8) is converted into a high-voltage voltage in the high-voltage vehicle electrical system (3) by the first DC / DC converter (6).

Description

The invention relates to an on-board power supply system arrangement for an electrically driven vehicle according to the preamble of claim 1, an electrically driven vehicle according to the preamble of claim 7 and a method for pre-charging a high-voltage on-board power supply system according to the preamble of claim 9.During the starting process of an electrically operated vehicle, capacitances of high-voltage components of a high-voltage on-board power supply are precharged either by a contactor composed of at least one high-voltage battery or by a DC / DC converter composed of a low-voltage system, in order to avoid high currents when a high-voltage battery is connected to the high-voltage on-board power supply.In the latter case, a low-voltage battery is required in the low-voltage system. The pre-charge time is limited by the power of the low-voltage battery, in particular at cold temperatures.DE 10 2020 007 060 A1 describes a pre-charging method for starting a high-voltage on-board power supply of an electrically operated vehicle with a high-voltage energy store, wherein the high-voltage energy store is electrically coupled to the high-voltage on-board power supply via an intermediate circuit, at least one low-voltage energy store, a time-based pre-charging circuit for the intermediate circuit, and a low-voltage on-board power supply with a DC / DC converter, which is designed for pre-charging the intermediate circuit via the low-voltage energy store. In this case, a pre-charge time window for pre-charging the intermediate circuit for the high-voltage on-board power supply is adapted if parameters of the low-voltage on-board power supply and / or of the low-voltage energy store are below a predefined limit value, or a charging power during pre-charging of the intermediate circuit is below a predefined limit power.The invention is based on the object of specifying a novel on-board power supply system arrangement for an electrically driven vehicle, a novel electrically driven vehicle and a novel method for precharging a high-voltage on-board power supply system.The object is achieved according to the invention by an on-board power supply system arrangement for an electrically driven vehicle having the features of claim 1, an electrically driven vehicle having the features of claim 7 and a method for pre-charging a high-voltage on-board power supply system having the features of claim 9.Advantageous embodiments of the invention are the subject matter of the dependent claims.An on-board power supply system for an electrically driven vehicle is proposed. The on-board power supply system comprises at least one high-voltage battery, one high-voltage on-board power supply system and at least one low-voltage on-board power supply system, wherein the high-voltage on-board power supply system and the high-voltage battery can be selectively connected to one another or disconnected from one another by at least one main contactor. A first DC / DC converter is connected with a high-voltage side to the high-voltage on-board power supply system and with a low-voltage side to a first low-voltage on-board power supply system. A second DC / DC converter is connected to the high-voltage battery with a high-voltage side and can be connected to the first low-voltage on-board power supply system or disconnected from it with a low-voltage side via a coupling element. The second DC / DC converter is configured to convert a high voltage of the high voltage battery into a low voltage on its low voltage side. According to the invention, the first DC / DC converter is configured to convert a low-voltage voltage from the low-voltage on-board power supply into a high-voltage voltage for the high-voltage on-board power supply, wherein a controller of the on-board power supply arrangement is configured to close the coupling element for precharging the high-voltage on-board power supply when the main contactor is open, to actuate the second DC / DC converter for converting the high-voltage from the high-voltage battery into a low-voltage voltage and to actuate the first DC / DC converter for converting the low-voltage present via the coupling element into a high-voltage in the high-voltage on-board power supply.In one specific embodiment, a voltage sensor system for detecting the voltage is situated in the high-voltage on-board power supply and is connected to the controller, which is configured to close the main contactor as soon as the high-voltage on-board power supply reaches the voltage level of the high-voltage battery.In one embodiment, a second low-voltage on-board power supply is connected to the low-voltage side of the second DC / DC converter.In one embodiment, a low-voltage battery is connected to the first or second low-voltage on-board power supply system.Each low-voltage on-board power supply system can have its own consumers.In one embodiment, at least one safety-critical load for a redundant supply is connected to the first low-voltage on-board power supply system and / or to the second low-voltage on-board power supply system.In one specific embodiment, the first DC / DC converter is also configured to convert the high-voltage voltage from the high-voltage on-board power supply system into a low-voltage voltage for the first low-voltage on-board power supply system. The first DC / DC converter is therefore designed in this case as a bidirectional DC / DC converter.According to one aspect of the present invention, an electrically driven vehicle having the above-described on-board power supply system is proposed, wherein the high-voltage battery is configured to supply power to an electric machine for driving the vehicle.In one specific embodiment, the at least one safety-critical load includes a brake system and / or a steering system of the vehicle and / or an advanced driver assistance system. The advanced driver assistance system, also known briefly as ADAS, is a driver assistance system having electronic additional devices in motor vehicles for assisting the driver in certain driving situations. Safety aspects play an important role here above all in planning, guiding and stabilizing a driving task, but are also otherwise always important in the driver assistance systems.According to one aspect of the present invention, a method for precharging a high-voltage on-board power supply system of an on-board power supply system of an electrically driven vehicle is proposed. The on-board power supply system comprises at least one high-voltage battery, one high-voltage on-board power supply system and at least one low-voltage on-board power supply system, wherein the high-voltage on-board power supply system and the high-voltage battery can be selectively connected to one another or disconnected from one another by at least one main contactor. A first DC / DC converter is connected with a high-voltage side to the high-voltage on-board power supply system and with a low-voltage side to a first low-voltage on-board power supply system. A second DC / DC converter is connected to the high-voltage battery with a high-voltage side and can be connected to the first low-voltage on-board power supply system or disconnected from it with a low-voltage side via a coupling element. The second DC / DC converter is configured to convert a high voltage of the high voltage battery into a low voltage on its low voltage side. According to the invention, for precharging the high-voltage on-board power supply system when the main contactor is open, the coupling element is closed, the high-voltage from the high-voltage battery is converted by the second DC / DC converter to a low-voltage voltage, and the low-voltage voltage present via the coupling element is converted by the first DC / DC converter to a high-voltage in the high-voltage on-board power supply system.In one specific embodiment, the main contactor is closed as soon as the high-voltage on-board power supply system reaches the voltage level of the high-voltage battery.According to the present invention, it is provided that one DC / DC converter supports the low-voltage on-board power supply system, while the other DC / DC converter pre-charges the high-voltage on-board power supply system.It is advantageous here that no separately installed precharge circuit is required. Further, a low voltage battery is not required, but is not intended to be excluded. The precharge duration is therefore independent of a low-voltage battery. As a result, the pre-charge power can be increased, in particular at a low external temperature.Exemplary embodiments of the invention are explained in more detail below with reference to drawings.The following are shown: FIG. 1 shows a schematic view of an embodiment of an on-board power supply system for an electrically driven vehicle, FIG. 2 shows a schematic view of a further embodiment of an on-board power supply system for an electrically driven vehicle, FIG. 3 shows a schematic view of the on-board power supply system during the execution of a method for ring precharge, and FIG. 4 is a schematic view of an electrically driven vehicle.Corresponding parts are provided with the same reference numerals in all figures.FIG. 1 is a schematic view of an embodiment of an on-board power system arrangement 1 for an electrically driven vehicle 20. the on-board power system arrangement 1 comprises a high-voltage battery 2, a high-voltage on-board power system 3, in which at least one high-voltage component, for example an inverter for an electric drive machine, can be arranged, and at least one low-voltage on-board power system 4, 11. the high-voltage on-board power system 3 and the high-voltage battery 2 can be selectively connected to one another or disconnected from one another by at least one main contactor 5, in particular a plurality of main contactors 5. A first DC / DC converter 6 is connected to the high-voltage on-board power supply 3 and is therefore likewise optionally connectable to the high-voltage battery 2 or separable therefrom by means of the at least one main contactor 5. On a low-voltage side, the first DC / DC converter 6 is connected to a first low-voltage on-board power supply system 4. The first DC / DC converter 6 is configured to convert a low-voltage voltage from the low-voltage on-board power supply 4 into a high-voltage voltage for the high-voltage on-board power supply 3.Furthermore, the first DC / DC converter 6 can optionally also be configured to convert the high-voltage voltage from the high-voltage on-board power supply 3 into a low-voltage voltage for the low-voltage on-board power supply 4 and thus be configured bi-directionally. This is probably often the case and advantageous in the overall context of technology in electrically driven vehicles 20, but is not absolutely necessary for the basic idea of the invention, but only optional.A second DC / DC converter 7 is directly connected to the high-voltage battery 2. A low-voltage side of the second DC / DC converter 7 can be connected to the first low-voltage on-board power supply system 4 or disconnected therefrom via a coupling element 8, for example a relay, a contactor or a semiconductor circuit. Furthermore, electrical consumers 9 can be connected to the first low-voltage on-board power supply system 4. The second DC / DC converter 7 is configured to convert the high voltage of the high voltage battery 2 into a low voltage on its low voltage side.FIG. 2 is a schematic view of a further embodiment of an on-board power supply system 1 for an electrically driven vehicle 20.The on-board power supply system arrangement 1 corresponds to a large extent to the on-board power supply system arrangement 1 shown in FIG. 1, but contains further components. In particular, a low-voltage battery 10 can be connected to the first low-voltage on-board power supply 4. Furthermore, a second low-voltage on-board electrical system 11 can be connected to the low-voltage side of the second DC / DC converter 7, to which further electrical loads 12 can be connected. Furthermore, safety-critical loads 13 for a redundant supply can be connected both to the first low-voltage on-board power supply system 4 and to the second low-voltage on-board power supply system 11.FIG. 3 is a schematic view of the vehicle electrical system arrangement 1 when carrying out a method for ring precharge.First, the high-voltage on-board power supply 3 is discharged. The at least one main contactor 5 is open in this case.For precharging the high-voltage on-board power supply system 3, the coupling element 8 is closed. The second DC / DC converter 7 converts the high-voltage from the high-voltage battery 2 to a low-voltage voltage on its low-voltage side, to which the second low-voltage on-board power supply system 11 can be connected, from where it is fed via the closed coupling element 8 into the first low-voltage on-board power supply system 4. The first DC / DC converter 6 converts the low-voltage voltage from the first low-voltage on-board power supply 4 into a high-voltage voltage in the high-voltage on-board power supply 3 and pre-charges it. An energy flow E during the precharging from the high-voltage battery 2 via the second DC / DC converter 7, the coupling element 8 and the first DC / DC converter 6 to the high-voltage on-board power supply system 3 is illustrated by arrows in FIG. 3.When the high-voltage on-board power supply 3 reaches the voltage level of the high-voltage battery 2 (which can be detected by a voltage sensor system), the at least one main contactor 5 is closed and the precharged high-voltage on-board power supply 3 is thus connected to the high-voltage battery 2.The method for pre-charging the high-voltage on-board power supply system 3 can be carried out by a controller 14, which is configured to actuate the at least one main contactor 5, the first and second DC / DC converters 6, 7, the coupling element 8 and, if appropriate, the voltage sensor system.The solution described does not require an additional precharge circuit. A low-voltage battery 10 is also not required. If a low-voltage battery 10 is nevertheless provided, the pre-charge duration is independent of the low-voltage battery 10.The present invention proposes a pre-charging process of the high-voltage on-board power supply system 3, in which the pre-charging takes place via two DC / DC converters 6, 7 and via the low-voltage on-board power supply system 4, 11. A prerequisite for this is two separate DC / DC converters 6, 7, one of which is arranged in the high-voltage on-board power supply 3 downstream of the main contactors 5 and the other of which is in direct contact with the high-voltage battery 2 upstream of the main contactors 5. Both DC / DC converters 6, 7 supply at least a part of the low-voltage on-board power supply system 4, 11 and can be contacted with one another on their low-voltage sides via a coupling element 8.The low-voltage on-board power supply systems 4, 11 can perform different tasks and have consumers 9, 12, 13. The coupling element 8 can be present for redundancy reasons (with respect to the DC / DC converters 6, 7) or be used in a targeted manner for implementing the present invention. A low-voltage battery 10 can also optionally be arranged as a buffer in at least one of the two low-voltage on-board power supply systems 4, 11. Each low-voltage on-board power supply system 4, 11 can have its own consumers 9, 12 and both low-voltage on-board power supplies 4, 11 can be connected to safety-critical consumers 13 (redundancy). Because of the coupling element 8, only one of the low-voltage on-board power supply systems 4, 11 can also be connected to the safety-critical consumers 13.If the main contactors 5 are open (for example, at standstill, during parking, at rest), the high-voltage on-board electrical system 3 is without voltage and the first DC / DC converter 6 cannot supply the first low-voltage on-board electrical system 4 connected thereto. However, the safety-critical consumers 13 can be supplied with low-voltage voltage directly from the high-voltage battery 2 via the second DC / DC converter 7. This low-voltage voltage can furthermore be used to pre-charge the high-voltage on-board power supply system 3, in which the coupling element 8 connects the low-voltage sides of the two DC / DC converters 6, 7, wherein the first DC / DC converter 6 converts the low-voltage voltage back into high-voltage voltage and thus pre-charges the high-voltage on-board power supply system 3 with the main contactors 5 still open, so that the main contactors 5 can then be closed and then the normal supply of the first low-voltage on-board power supply system 4 from the high-voltage on-board power supply system 3 is possible again and the coupling element 8 can be opened again. Thus, a low voltage battery 10 is not required, but may still optionally be present. A pre-charge is then also possible independently of its charge state.The on-board power supply system device 1 can be arranged in an electrically driven vehicle 20, it being possible for the high-voltage battery 2 to be used to supply power to an electric machine for driving the vehicle 20. The consumers 9, 12, 13 are safety-critical consumers 13 and non-safety-critical consumers 9, 12 of the vehicle 20.Safety-critical consumers 13 can be, for example, a brake system and / or a steering system of the vehicle 20. Non-safety-critical consumers 9, 12 can comprise, for example, entertainment electronics, interior lighting and air conditioning of the vehicle 20.FIG. 4 is a schematic view of an electrically driven vehicle 20 that may be equipped with the onboard electrical system device 1 described above and illustrated in FIGS. 1 to 3. The vehicle 20 may be, for example, a passenger car, a commercial vehicle or bus.List of reference characters1 On-board power supply system 2 High-voltage battery 3 High-voltage on-board power supply system 4 Low-voltage on-board power supply system, first low-voltage on-board power supply system 5 Main contactor 6 First DC / DC converter 7 Second DC / DC converter 8 Coupling element 9 Load 10 Low-voltage battery 11 Low-voltage on-board power supply system, second low-voltage on-board power supply system 12 Load 13 Load, safety-critical load 14 Controller 20 Vehicle E Energy flowReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2020 007 060 A1

[0004]

Claims

An on-board power supply system (1) for an electrically driven vehicle (20), comprising at least one high-voltage battery (2), a high-voltage on-board power supply system (3) and at least one low-voltage on-board power supply system (4, 11), wherein the high-voltage on-board power supply system (3) and the high-voltage battery (2) can be selectively connected to one another or disconnected from one another by at least one main contactor (5), wherein a first DC / DC converter (6) is connected to the high-voltage on-board power supply system (3) by a high-voltage side and to a first low-voltage on-board power supply system (4) by a low-voltage side, wherein a second DC / DC converter (7) is connected to the high-voltage battery (2) by a high-voltage side and can be connected to the first low-voltage on-board power supply system (4) by a coupling element (8) or disconnected therefrom, wherein the second DC / DC converter (7) is configured to convert a high-voltage voltage of the high-voltage battery (2) into a low-voltage voltage on its low-voltage side, characterized in that the first DC / DC converter (6) is configured to convert a low-voltage voltage from the low-voltage on-board power supply (4) into a high-voltage for the high-voltage on-board power supply (3), wherein a controller (14) of the on-board power supply arrangement (1) is configured to close the coupling element (8) for precharging the high-voltage on-board power supply (3) when the main contactor (5) is open, the second DC / DC converter (7) for converting the high-voltage from the high-voltage battery (2) to a low-voltage voltage and for controlling the first DC / DC converter (6) for converting the low-voltage present via the coupling element (8) into a high-voltage in the high-voltage on-board electrical system (3).On-board power supply system arrangement (1) according to Claim 1, characterized in that a voltage sensor system for detecting the voltage in the high-voltage on-board power supply system (3) is arranged and connected to the controller (14), which is configured to close the main contactor (5) as soon as the high-voltage on-board power supply system (3) reaches the voltage level of the high-voltage battery (2).On-board power supply system arrangement (1) according to Claim 1 or 2, characterized in that a second low-voltage on-board power supply system (11) is connected to the low-voltage side of the second DC / DC converter (7).On-board power supply system arrangement (1) according to one of the preceding claims, characterized in that a low-voltage battery (10) is connected to the first (4) or second (11) low-voltage on-board power supply system.On-board power supply system arrangement (1) according to one of the preceding claims, characterized in that at least one safety-critical load (13) for a redundant supply is connected to the first low-voltage on-board power supply system (4) and / or to the second low-voltage on-board power supply system (11).On-board power supply system arrangement (1) according to one of the preceding claims, characterized in that the first DC / DC converter (6) is configured to convert the high-voltage voltage from the high-voltage on-board power supply system (3) into a low-voltage voltage for the first low-voltage on-board power supply system (4)Electrically driven vehicle (20) having an on-board power supply system arrangement (1) according to one of the preceding claims, characterized in that the high-voltage battery (2) is configured to supply power to an electric machine for driving the vehicle (20).Electrically driven vehicle (20) according to Claim 7, characterized in that the at least one safety-critical load (13) comprises a brake system and / or a steering system of the vehicle (20) and / or an advanced driver assistance system.Method for pre-charging a high-voltage on-board power supply system (3) of an on-board power supply system (1) of an electrically driven vehicle (20), wherein the on-board power supply system (1) has at least one high-voltage battery (2), a high-voltage on-board power supply system (3) and at least one low-voltage on-board power supply system (4, 11), wherein the high-voltage on-board power supply system (3) and the high-voltage battery (2) can be selectively connected to one another or disconnected from one another by at least one main contactor (5), wherein a first DC / DC converter (6) is connected to the high-voltage on-board power supply system (3) by a high-voltage side and to a first low-voltage on-board power supply system (4) by a low-voltage side, wherein a second DC / DC converter (7) is connected to the high-voltage battery (2) with a high-voltage side and is connectable to the first low-voltage on-board power supply system (4) or is separable from it with a low-voltage side via a coupling element (8), wherein the second DC / DC converter (7) is configured to convert a high-voltage of the high-voltage battery (2) into a low-voltage on its low-voltage side, characterized in that, for precharging the high-voltage on-board power supply system (3) when the main contactor (5) is open, the coupling element (8) is closed, by the second DC / DC converter (7) the high-voltage from the high-voltage battery (2) is converted into a low-voltage voltage and by the first DC / DC converter (6) the low-voltage present via the coupling element (8) is converted into a high-voltage in the high-voltage on-board electrical system (3).Method according to Claim 9, characterized in that the main contactor (5) is closed as soon as the high-voltage on-board power supply system (3) reaches the voltage level of the high-voltage battery (2).

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