DE102021119957A1 - Method and device for operating energy generators for a vehicle electrical system - Google Patents

Abstract

A device (200) for operating a plurality of energy generators (201, 202, 223) for providing electrical energy in an on-board electrical system (220) of a vehicle (100) is described. The device (200) is set up to cause a first energy generator (201) to be operated in order to set, in particular to regulate, an actual voltage (231) at a reference point (242) of the vehicle electrical system (220) to a desired voltage value . The device (200) is also set up to cause a second energy generator (202, 223) to be operated depending on a load (310) of the first energy generator (201) in order to provide electrical energy in the vehicle electrical system (220).

Description

The invention relates to a method and a corresponding device for operating different energy generators to provide electrical energy in an electrical vehicle electrical system.

A vehicle has an on-board electrical system for supplying electrical energy to various electrical consumers in the vehicle. When the number of electrical consumers in the vehicle electrical system increases, the electrical energy requirement in the vehicle electrical system typically also increases. The increased energy requirement can be covered, for example, by providing one or more additional energy generators, with an energy generator being set up to transfer electrical energy from another vehicle electrical system (e.g. from a high-voltage vehicle electrical system) to the electrical system with the electrical consumers .

The operation of several electrical energy generators to cover the energy requirement in an on-board network can lead to inefficiencies and/or instabilities in the energy supply of the on-board network.

This document deals with the technical task of enabling the most efficient and stable possible energy supply to an electrical vehicle on-board network from several electrical energy suppliers.

The object is solved by each of the independent claims. Advantageous embodiments are described inter alia in the dependent claims. It is pointed out that additional features of a patent claim dependent on an independent patent claim without the features of the independent patent claim or only in combination with a subset of the features of the independent patent claim can form a separate invention independent of the combination of all features of the independent patent claim, which can be made the subject of an independent claim, a divisional application or a subsequent application. This applies equally to the technical teachings described in the description, which can form an invention independent of the features of the independent patent claims.

According to one aspect, a device for operating a plurality of energy generators for providing electrical energy in an on-board electrical system of a (motor) vehicle is described. The vehicle electrical system can be a low-voltage vehicle electrical system, e.g. with a nominal voltage of 60V or less, in particular with a nominal voltage of 12V or 48V.

The device is set up to cause a first energy generator (e.g. a first DC-DC converter) to be operated in order to adjust, in particular to regulate, the actual voltage at a reference point of the vehicle electrical system to a voltage setpoint value. The reference point can be arranged on an electrical energy store, in particular on the terminals of an energy store, of the vehicle electrical system. The first energy generator can be designed to transfer electrical energy from another vehicle electrical system (e.g. from a high-voltage vehicle electrical system with a nominal voltage of 300V or more) to the vehicle electrical system.

The device can be set up to determine measurement data relating to the actual voltage at the reference point (e.g. using a voltage measuring unit at the reference point). Furthermore, the device can be set up to operate the first energy generator as a function of the measurement data, in particular in order to regulate the actual voltage to the desired voltage value. For this purpose, e.g. the duty cycle of the first DC-DC converter can be changed as a manipulated variable. The first energy generator can thus be operated as a voltage regulator in order to set the actual voltage at a specific reference point in the vehicle's electrical system to a desired voltage value.

Furthermore, the device is set up to cause (at least) a second energy generator (e.g. a second DC-DC converter) to be operated depending on the utilization of the first energy generator in order to provide electrical energy in the vehicle electrical system. The first energy generator can, for example, have a maximum possible power and/or a maximum possible duty cycle. The utilization can show, for example, the proportion (e.g. the percentage) of the maximum possible power and/or the maximum possible duty cycle with which the first energy producer (at a specific point in time) is operated.

In particular, the device can be set up to determine utilization information relating to the current utilization of the first energy producer. The utilization information can display the proportion (eg the percentage) of the maximum possible power and/or the maximum possible duty cycle with which the first energy generator is operated. The second energy generator can then be operated as a function of the utilization information, in particular in order to ensure that the utilization of the first energy generator gers does not exceed a certain load threshold.

The combination of a first energy producer, which (preferably alone) brings about the voltage regulation in the vehicle electrical system, and at least one second energy producer, which supports the first energy producer in order to limit the utilization of the first energy producer, can result in a particularly efficient and stable energy supply to the vehicle electrical system become.

The device can be set up to cause the second energy producer to be operated in order to set, in particular to regulate, the actual utilization of the first energy producer to a desired utilization value.

At a first load, the first energy generator can have an optimum degree of efficiency for providing electrical energy in the vehicle electrical system. In other words, the first energy generator can be designed in such a way that the first energy generator has a (local or global) efficiency optimum with regard to the provision of electrical energy in the vehicle electrical system when it is first utilized.

The desired utilization value can then preferably be such that the desired utilization value deviates from the first utilization by at most 10%. Alternatively or additionally, the device can be set up to cause the second energy producer to be operated in such a way that the actual utilization of the first energy producer deviates from the first utilization by at most 10%, at least on average over time.

The second energy producer can thus be used to adjust the utilization of the first energy producer to a specific (optimal) nominal utilization value. For this purpose, utilization information relating to the utilization of the first energy producer can be determined (repeatedly), and the second energy producer can be operated as a function of the current utilization information. For example, a manipulated variable (e.g. the duty cycle) of the second energy generator can be adjusted as a function of the utilization information, in particular as a function of the deviation between the actual utilization and the utilization target value.

Adjusting the utilization of the first energy generator to a setpoint utilization value makes it possible to operate the vehicle electrical system in a particularly energy-efficient and stable manner.

The device can be set up to cause the second energy generator to be operated in order to provide a specific target current and/or a specific target power in the vehicle electrical system. Current and/or power regulation of the second energy generator can thus be effected in order to further increase the stability of the operation of the vehicle electrical system.

The device can be set up to detect that the actual utilization of the first energy producer is equal to or greater than an upper utilization threshold value. In response to this, the second energy generator in the vehicle electrical system can provide an electrical power that is increased by a certain quantity and/or an electrical current that is increased by a certain quantity. A gradual increase in the power provided by the second energy generator can thus be brought about. For example, the entire possible power range of the second energy generator can be divided into 3 to 10 steps. The quantitative value can thus be between 1/10 to 1/3 of the entire possible power range of the second energy generator. By gradually increasing the power provided, the stability and energy efficiency of the vehicle electrical system can be further increased.

Correspondingly, the device can be set up to detect that the actual utilization of the first energy producer is equal to or lower than a lower utilization threshold value (where the lower utilization threshold value is equal to or lower than the upper utilization threshold value) . In a preferred example, the lower utilization threshold value is less than the upper utilization threshold value minus a utilization difference of the first energy producer, which is caused by the above-mentioned amount of electricity or power of the second energy producer. A particularly stable operation of the energy supply of the vehicle electrical system can be made possible in this way.

In response to the detected reduction in utilization, the second energy generator in the vehicle electrical system can provide an electrical power reduced by the specific quantity value and/or an electric current reduced by the specific quantity value. By gradually reducing the power provided, the stability and energy efficiency of the vehicle electrical system can be further increased.

The device can be set up to ensure that the second energy generator is only then used to provide electrical energy in the vehicle electrical system is operated when the electrical power to be provided by the second energy generator and/or when the current to be provided by the second energy generator reaches or exceeds a predefined minimum value.

Alternatively or additionally, the device can be set up to check (before activating the second energy generator) whether the electrical power to be provided by the second energy generator and/or the current to be provided by the second energy generator reaches or exceeds a predefined minimum value. Furthermore, the device can be set up to ensure that the second energy generator is only operated to provide electrical energy in the vehicle electrical system when the electrical power to be provided by the second energy generator and/or when the current to be provided by the second energy generator exceeds the predefined Minimum value reached or exceeded.

It can thus be brought about that the second energy generator is only operated with a specific minimum output. In this way, the energy efficiency of the vehicle electrical system can be further increased.

The device can be set up to detect that a voltage, in particular the actual voltage at the reference point, of the vehicle electrical system has reached or fallen below a minimum voltage. In response to this, it can then (automatically) be brought about that the second energy producer (possibly independently of the utilization of the first energy producer) is operated in order to provide electrical energy in the vehicle electrical system. An emergency supply can thus be provided by the second energy supplier. In this way, the stability of the vehicle electrical system can be further increased.

The device can be set up to repeatedly determine temperature data relating to the temperature of the first energy generator and/or the second energy generator at a sequence of times. The temperature data can be recorded, for example, using a temperature sensor.

Furthermore, the device can be set up to set and/or adapt the power distribution of the first power provided by the first energy generator in the vehicle electrical system and the second power provided by the second energy generator in the vehicle electrical system as a function of the temperature data.

In particular, the device can be set up to determine on the basis of the temperature data that the temperature of the first energy generator has reached or exceeded a temperature threshold value. In response, the first power can then be caused to decrease and the second power to increase (so that the sum of the first and second powers remains constant). Alternatively or additionally, it can be determined on the basis of the temperature data that the temperature of the second energy generator has reached or exceeded a temperature threshold value. The first power can then be caused to increase and the second power to decrease in response (such that the sum of the first and second powers remains constant).

The power distribution between the energy generators can thus be used to keep the temperatures of the energy generators below a specific temperature threshold value. In this way, the cooling requirements for the vehicle electrical system can be reduced and thus the energy efficiency of the vehicle electrical system can be increased.

As already explained above, the first energy generator and/or the second energy generator can each include a DC-DC converter that is set up to transfer electrical energy from another vehicle electrical system, in particular from a high-voltage vehicle electrical system, to the vehicle electrical system.

According to a further aspect, an on-board electrical system for a vehicle is described, which includes the device described in this document.

According to a further aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described which comprises the device described in this document and/or the vehicle electrical system described in this document.

According to a further aspect, a method for operating a plurality of energy generators for providing electrical energy in an on-board electrical system of a vehicle is described. The method includes the operation of a first energy generator in order to set, in particular to regulate, the actual voltage at a reference point of the vehicle electrical system to a voltage setpoint. The method also includes the operation of a second energy generator depending on a utilization of the first energy generator to provide electrical energy in the vehicle electrical system.

According to a further aspect, a software (SW) program is described. The SW program can be set up to run on a processor (e.g. on a vehicle's control unit), and thereby the in the carry out the procedures described in this document.

According to a further aspect, a storage medium is described. The storage medium can comprise a SW program which is set up to be executed on a processor and thereby to carry out the method described in this document.

It should be noted that the methods, devices and systems described in this document can be used both alone and in combination with other methods, devices and systems described in this document. Furthermore, any aspects of the methods, devices and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in many different ways. Furthermore, features listed in brackets are to be understood as optional features.

• 1 ein beispielhaftes Fahrzeug mit einem elektrischen Gesamt-Bordnetz;
• 2 ein beispielhaftes elektrisches Gesamt-Bordnetz eines Fahrzeugs;
• 3 einen beispielhaften zeitlichen Verlauf der Auslastung eines ersten Energieerzeugers eines Bordnetzes; und
• 4 ein Ablaufdiagramm eines beispielhaften Verfahrens zum Betrieb von unterschiedlichen Energieerzeugern zur Versorgung eines elektrischen Fahrzeug-Bordnetzes.

The invention is described in more detail below using exemplary embodiments. show it

• 1 an exemplary vehicle with an overall electrical system;
• 2 an exemplary overall electrical system of a vehicle;
• 3 an exemplary time course of the utilization of a first energy generator of a vehicle electrical system; and
• 4 a flowchart of an exemplary method for operating different energy generators to supply an electrical vehicle electrical system.

As explained at the outset, this document is concerned with enabling the most efficient and stable electrical energy supply possible for a (partial) on-board network of a vehicle. In this context shows 1 an exemplary vehicle 100 with an (entire) vehicle electrical system 100. Furthermore, FIG 2 exemplary components of an (overall) vehicle electrical system 100 with several (partial) vehicle electrical systems 210, 220. The first (partial) vehicle electrical system 210 can have a first nominal voltage and the second (partial) vehicle electrical system 220 can have a second nominal voltage. In this case, the first nominal voltage can be greater than the second nominal voltage. For example, the first nominal voltage can be in the high-voltage (HV) range, for example 300V or more. The second nominal voltage can be in the low-voltage (NV) range, for example 60V or less, in particular 48V or 12V.

The first vehicle electrical system 210 can include a first energy store 211 (e.g. a lithium-ion-based store) and one or more first electrical loads 214 (e.g. an electric drive motor of the vehicle 100). The second vehicle electrical system 220 can include a second energy store 221 (e.g. a lead battery or a lithium-ion based store) and a multiplicity of second electrical consumers 224 . Exemplary second electrical consumers 224 are: one or more lighting elements (e.g. headlights, rear lights, interior lighting, etc.), an infotainment system, an air conditioning system, seat heating, etc.

The electrical energy for operating the second (partial) vehicle electrical system 220 can be provided by one or more energy generators 201, 202, 223. An energy generator 201, 202, 223 can include a DC voltage converter 201, 202 which is set up to transfer electrical energy from the first vehicle electrical system 210 to the second vehicle electrical system 220. Alternatively or additionally, an energy generator 201, 202, 223 can include a generator 223, which is driven by an internal combustion engine of vehicle 100 and/or by the wheels of vehicle 100 in order to generate electrical energy.

For stable and/or energy-efficient operation of second vehicle electrical system 220, the voltage at a specific reference point of second vehicle electrical system 220 is typically set, in particular regulated, to a specific setpoint value. However, if several energy generators 201, 202, 223 provide electrical energy in the second vehicle electrical system 220, there may be conflicts between the different energy producers 201, 202, 223 and thus instabilities in the second vehicle electrical system 220 if several energy generators 201, 202, 223 voltage regulation takes place at the same time. This can be the case in particular when the different energy generators 201, 202, 223 feed electrical energy into the second vehicle electrical system 220 at different points 241, 242, 243 and/or when the different energy generators 201, 202, 223 depending on the j respective actual voltage 231 at different points 241, 242, 243 in the second vehicle electrical system 220, in particular regulated.

A (control) device 200 of the vehicle electrical system 110 and/or the vehicle 100 can be set up to cause electrical energy to be provided in the second vehicle electrical system 220 by a first (possibly main) energy generator 201 in such a way that the actual Voltage 231 is set at a specific first reference point 241 to a specific setpoint. In particular, the first energy generator 201 for voltage regulation at a first reference point 241 can be used. The first reference point 241 can, for example, be arranged in the immediate vicinity (eg between the terminals) of the second electrical energy store 221 (because the second energy store typically already has a voltage measuring unit).

The one or more other (second) energy generators 202, 223 can be designed to provide electrical energy in the second vehicle electrical system 220 without voltage regulation. If necessary, electrical energy can be provided selectively by the one or more other energy generators 202, 223, e.g. if it is recognized that the utilization of the first energy generator 201 has reached or exceeded a specific utilization threshold value.

Another energy generator 202, 223 can then provide electrical energy with current regulation, in which the actual current 232 provided by the other energy generator 202, 223 is set to a specific desired value. As an alternative or in addition, a power control can take place, in which the electrical power provided by the other energy generator 202, 223 is set to a specific desired value.

A first generator (main generator) 201 can thus be controlled (in particular regulated) via a voltage specification. This enables the use of existing control algorithms and a stable adjustment of the voltage in the second vehicle electrical system 220. This also enables a modular design of the second vehicle electrical system 220 (e.g. for different equipment variants of the vehicle 100).

The one or more additional generators 202, 223 can be controlled or regulated depending on the utilization of the main generator 201, e.g. by specifying a target current. The main generator 201 thus supplies the stability of the voltage level in the second vehicle electrical system 220. In the event of increased loads, the one or more additional generators 202, 223 allow additional electrical power to be provided. Voltage offsets due to lines between different reference points 241, 242, 243 or structural tolerances of the energy generators 201, 202, 223 then no longer have any influence on the stability and the energy efficiency of the second vehicle electrical system 220.

For example, the voltage 231 at the reference point 242 of the second energy store 221 can be set to a specific target voltage (e.g. 14V) in the second vehicle electrical system 220 as a default in order to ensure that the electrical energy store 221 is charged continuously. For this purpose, the main generator 201 can be given a suitable setpoint voltage, which compensates for any voltage drops on the lines of the vehicle electrical system 220 (between the main generator 201 and the reference point 242).

Furthermore, the utilization of the main generator 201 can be monitored. As soon as the utilization of the main generator 201 reaches or exceeds a specific utilization threshold value, one or more additional generators 202, 223 can be operated in order to additionally provide electrical energy in the vehicle electrical system 220. For this purpose, for example, a target current can be specified in each case, which is to be fed into vehicle electrical system 220. As a result of this, the main generator 201 can reduce the electrical power provided by the main generator 201 in order to keep the voltage at the specified target value. The plurality of generators 201, 202, 223 can thus be kept in a desired, ideal state of utilization without component tolerances or further voltage drops between the other generators 201, 202, 223 and the energy store 221 having to be taken into account and/or compensated for.

The one or more other energy generators 202, 223 can only be switched on if the one or more energy generators 202, 223 can each supply a certain minimum output, which enables the one or more other energy generators 202, 223 to be relatively efficient . A DC-DC converter 202 typically has relatively poor efficiency at relatively low power. An energy generator 202, 223 can thus be activated as soon as the energy generator 202, 223 can be operated with an efficiency which is equal to or greater than a specific minimum efficiency.

The one or more other generators 202, 223 can receive a stepped current specification for providing electrical energy. At the activation threshold, a generator 202, 223 can request e.g. 10A, with the result that the utilization of the main generator 201 decreases. If the utilization of the main generator 201 continues to increase, 20A can be requested when the utilization threshold is reached again, and so on.

If the utilization of the main generator 201 drops, the electricity provided by a further generator 202, 223 or the power provided by a further generator 202, 223 can be gradually reduced in an analogous manner.

3 shows an example of a time profile 320 of the utilization 310 of the main generator 201. The device 200 can be set up to increase the electrical power provided by a further generator 202, 223 or the electricity 232 provided by a certain quantity value if the utilization 310 exceeds the upper Utilization threshold 311 reached or exceeded. On the other hand, the device 200 can be set up to reduce the electrical power or current 232 provided by the specific quantity value if the load 300 reaches or falls below the lower load threshold value 312 . As a result, the utilization 300 decreases or increases by a specific utilization (difference) value 321.

in the in 3 In the illustrated example curve 320 of utilization 310 as a function of time 300, utilization 310 reaches upper utilization threshold value 311 at first point in time 301, so that at least one additional generator 202, 223 is activated to generate a power or current 232 according to the quantity value to provide. In response to this, the load 310 of the main producer 201 falls by the load value 321, but then increases again in the example shown, until the upper load threshold value 311 is reached again at the second point in time 302. Thereupon twice the quantity value of power or current 232 is requested from the additional producer 202 , 223 , which leads to a reduction in the utilization 310 of the main producer 201 by the utilization value 321 .

In the example shown, the power requirement in the vehicle electrical system 220 then drops, so that the utilization 310 of the main generator 201 reaches the lower utilization threshold value 312 at the third point in time 303, which means that the additional generator 202, 223 required power or current 232 are reduced by the quantity value. The utilization 310 of the main generator 201 then increases by the utilization value 321, but in the example shown it again reaches the lower utilization threshold value 312 by the fourth point in time 304, which leads to a further reduction in the output from the additional generator 202, 223 required power or current leads (in particular, this can lead to a deactivation of the other generator 202, 223).

A particularly efficient and stable operation of the vehicle electrical system 220 can be made possible by such a gradual adjustment of the power or current requested by a further generator 202, 223. Furthermore, a tuning of a controller can thus be dispensed with.

The one or more additional generators 202, 223 can receive a regulated current specification, in which the utilization 310 of the main generator 201 is kept at a defined value. This control point is preferably set to the optimum efficiency of the main generator 201 . The utilization 310 of the main generator 201 can thus be used as a control variable for operating the one or more other generators 202, 223. In particular, the one or more additional generators 202, 223 can be operated in such a way that the actual utilization 310 of the main generator 201 has a specific utilization target value. In this case, the target value of the load 310 can depend on the optimum efficiency of the main generator 201 . In particular, the target value of the load 310 can be such that the main generator 201 has the optimum efficiency with a load 310 corresponding to the target value. A particularly efficient operation of the vehicle electrical system 220 can thus be made possible.

The robustness of vehicle electrical system 220 against voltage dips during power peaks can be increased in particular by specifying a lower limit voltage of voltage 231 in vehicle electrical system 220 for one or more other generators 202, 223, at which the one or more other generators 202, 223 autonomously generate electric power Feed energy into the second vehicle electrical system 220, possibly independently of a current specification and/or of a utilization 310 of the main generator 201.

The one or more additional generators 202, 223 can thus be set up to monitor the actual voltage 231 in the vehicle electrical system 220. If it is detected that the actual voltage 231 has reached or fallen below a voltage threshold value, the operation of the one or more additional generators 202, 223 can be started automatically and/or autonomously (possibly without current and/or power regulation). provide electrical energy in the vehicle electrical system 220. A particularly stable operation of the vehicle electrical system 220 can be made possible in this way.

The temperature of the individual generators 201, 202, 223 can be taken into account in the power distribution between the different generators 201, 202, 223. If the temperature of a generator 201, 202, 223 reaches or exceeds a certain temperature threshold value, the power provided by this generator 201, 202, 223 can be reduced, and the power provided by the one or more other generators 201, 202, 223 accordingly increase. By redistributing the performance requirements to different generators 201, 202, 223, a particularly efficient cooling of the producers 201, 202, 223 are enabled. In particular, a cooling system for the generators 201, 202, 223 can be designed with a reduced cooling capacity and thus with reduced costs.

4 shows a flowchart of a (possibly computer-implemented) method 400 for operating a plurality of energy generators 201, 202, 223 (in particular DC-DC converters) to provide electrical energy in an electrical system 220 (in particular in a LV vehicle electrical system) of a vehicle 100.

The method 400 includes the operation 401 of a first energy generator 201 in order to set, in particular to regulate, the actual voltage 231 at a reference point 242 of the vehicle electrical system 220 (e.g. at the terminals of an energy store 221 of the vehicle electrical system 220). The first energy generator 201 can thus be operated with voltage regulation in order to regulate the actual voltage 231 at the reference point 242 to the desired voltage value. A stable vehicle electrical system voltage can thus be provided in an efficient manner.

The method 400 also includes the operation 402 of a second energy generator 202 , 223 depending on the utilization 310 of the first energy generator 201 in order to provide (additional) electrical energy in the vehicle electrical system 220 . For this purpose, the actual utilization 310 of the first energy producer 201 can be determined (repeatedly, at a sequence of times). The operation of the second energy generator 202, 223 can then be adapted in each case as a function of the respectively determined actual utilization 310 of the first energy generator 201, in particular in order to set the actual utilization 310 to a specific utilization target value. A particularly energy-efficient provision of electrical energy can be brought about in this way.

The present invention is not limited to the exemplary embodiments shown. In particular, it should be noted that the description and the figures are only intended to illustrate the principle of the proposed methods, devices and systems by way of example.

Claims (12)

Device (200) for operating a plurality of energy generators (201, 202, 223) to provide electrical energy in an electrical system (220) of a vehicle (100); wherein the device (200) is set up - Cause a first energy generator (201) to be operated in order to set an actual voltage (231) at a reference point (242) of the vehicle electrical system (220) to a desired voltage value, in particular to regulate it; and - to cause a second energy generator (202, 223) depending on a load (310) of the first energy generator (201) is operated to provide electrical energy in the vehicle electrical system (220). Device (200) according to claim 1 , wherein the device (200) is set up to cause the second energy generator (202, 223) to be operated in order to adjust the actual utilization (310) of the first energy generator (201) to a utilization target value, in particular to regulate it. Device (200) according to claim 2 , wherein - the first energy generator (201) has an optimal efficiency for providing electrical energy in the vehicle electrical system (220) at a first load; and - the load target value differs from the first load by a maximum of 10%; and/or - the device (200) is set up to cause the second energy generator (202, 223) to be operated in such a way that the actual utilization (310) of the first energy generator (201), at least on average over time, by at most 10% deviates from the first load. Device (200) according to one of the preceding claims, wherein the device (200) is set up to cause the second energy generator (202, 223) to be operated in order to generate a specific target current and/or a specific target power in the vehicle electrical system (220) to provide. Device (200) according to one of the preceding claims, wherein the device (200) is set up - to detect that an actual utilization (310) of the first energy producer (201) is equal to or greater than an upper utilization threshold value (311); and - In response to this, the second energy generator (202, 223) in the vehicle electrical system (220) provides an electrical power increased by a specific quantity value and/or an electric current (232) increased by a specific quantity value. Device (200) according to one of the preceding claims, wherein the device (200) is set up - to detect that an actual utilization (310) of the first energy generator (201) is equal to or smaller than a lower utilization threshold value (312) is; and - to cause in response to that of the second energy generator (202, 223) in the vehicle electrical system (220) by a specific quantity value reduced electrical power and/or an electrical current (232) reduced by a specific quantity value are provided. Device (200) according to any one of the preceding claims, wherein - The device (200) is set up to ensure that the second energy generator (202, 223) is only operated to provide electrical energy in the vehicle electrical system (220) when an electrical energy to be provided by the second energy generator (202, 223). power and/or when a current (232) to be provided by the second energy generator (202, 223) reaches or exceeds a predefined minimum value; and or - the device (200) is set up, - to check whether an electrical power to be provided by the second energy generator (202, 223) and/or a current (232) to be provided by the second energy generator (202, 223) reaches or exceeds a predefined minimum value; and - cause the second energy generator (202, 223) to be operated to provide electrical energy in the vehicle electrical system (220) only when the electrical power to be provided by the second energy generator (202, 223) and/or when the second energy generator (202, 223) to be provided current (232) reaches or exceeds the predefined minimum value. Device (200) according to one of the preceding claims, wherein the device (200) is set up - To detect that a voltage (231), in particular the actual voltage (231) at the reference point (242), of the vehicle electrical system (220) has reached or fallen below a minimum voltage; and - In response to this, causing the second energy generator (202, 223) to be operated independently of the load (310) of the first energy generator (201) in order to provide electrical energy in the vehicle electrical system (220). Device (200) according to one of the preceding claims, wherein the device (200) is arranged to repeat at a sequence of times - determine temperature data relating to a temperature of the first energy generator (201) and/or the second energy generator (202, 223); and - setting and/or adapting a power distribution of a first power provided by the first energy generator (201) in the vehicle electrical system (220) and a second power provided by the second energy generator (202, 223) in the vehicle electrical system (220) as a function of the temperature data . Device (200) according to claim 9 , wherein the device (200) is set up - to determine on the basis of the temperature data that the temperature of the first energy generator (201) reaches or exceeds a temperature threshold value; and - in response thereto causing the first power to be reduced and the second power to be increased; and/or - to determine on the basis of the temperature data that the temperature of the second energy generator (202, 223) reaches or exceeds a temperature threshold value; and - in response thereto causing the first power to increase and the second power to decrease. Device (200) according to one of the preceding claims, wherein the first energy generator (201) and/or the second energy generator (202, 223) each comprise a DC/DC converter which is set up to convert electrical energy from another vehicle electrical system (210) of the vehicle (100 ), In particular from a high-voltage vehicle electrical system, to be transferred to the vehicle electrical system (220). Method (400) for operating a plurality of energy generators (201, 202, 223) to provide electrical energy in an electrical system (220) of a vehicle (100); the method (400) comprising - Operating (401) a first energy generator (201) in order to set an actual voltage (231) at a reference point (242) of the vehicle electrical system (220) to a desired voltage value, in particular to regulate it; and - Operation (402) of a second energy generator (202, 223) depending on a load (310) of the first energy generator (201) to provide electrical energy in the vehicle electrical system (220).

Images