Electrically powered vehicle

Abstract

An electrically powered vehicle (10) comprising an electric drive (126) for propelling the vehicle (10); a fuel cell (14) for generating electrical and thermal energy; an electrically rechargeable high-voltage vehicle battery (124) for supplying the electric drive (126), which can be heated with thermal energy from the fuel cell (14); and a low-voltage electrical system (108) for supplying further low-voltage electrical consumers (114); is characterized in that the low-voltage electrical system (108) can be supplied with low-voltage energy from the fuel cell (14).

Description

Technical FieldThe invention relates to an electrically operated vehicle, containing (a) an electric drive for moving the vehicle; (b) a fuel cell for generating electrical and thermal energy; (c) an electrically rechargeable high-voltage vehicle battery for supplying the electric drive, which battery can be heated with thermal energy of the fuel cell; and (d) a low-voltage on-board electrical system for supplying further electrical low-voltage loads.The invention further relates to a retrofit module for retrofitting and to a method for operating such an electrically operated vehicle.A vehicle may be moved to land, water, or in the air. In particular, a vehicle may be a passenger car, trucks, recreational vehicles, sailboats, ships, aircraft, motor cycles and the like.In the past, most vehicles have been operated with fossil fuels, for example in an internal combustion engine. To achieve climate neutrality, other solutions are now sought. In particular, vehicles with an electric drive and a powerful vehicle battery are already available in series. Drives with a fuel cell are also known.In internal combustion engines, energy chemically stored in the fuel is first converted into thermal energy and then into mechanical work. In electrically powered vehicles, the energy stored in a battery is converted to mechanical work via an electric drive. In a fuel cell, the energy chemically stored in a fuel, such as hydrogen, is directly converted to electrical energy and then to mechanical work.Besides these drive forms, hybrid forms, also referred to as hybrid drive, are known. These use a conventional internal combustion engine and an additional electrically operated drive with battery as energy store. As long as the battery supplies energy, the vehicle is driven exclusively with electrical energy. The internal combustion engine is then used as a main drive. Depending on the design, the battery can be charged by recuperation or, in the case of plug-in hybrids, at external energy sources. In hybrid drives, two main drives and two associated energy stores-battery and fuel tank-are used. These are of complex construction and have a high weight and thus increase the production costs, the maintenance effort and the energy requirement.Disadvantages of exclusively electrically driven vehicles are the limited range, the long time for charging and the short service life of the batteries. These disadvantageous effects occur more strongly at low temperatures, i.e. in particular in cold regions, at night and in winter. At low temperatures, the efficiency of the battery decreases. This requires heating of the battery. The heater is operated with power from the vehicle battery. This also applies to the passenger compartment. This too must be electrically heated for heating. This affects the range of the vehicle.Prior ArtDE 10 2011 076 737 A1 and DE 10 2017 002 854 A1 each disclose an electrically operated vehicle in which the traction battery is thermally coupled to an additional fuel cell. The thermal coupling can take place directly by spatial proximity or indirectly via a thermal energy management system, for example a heating and cooling circuit. The electrical energy generated by the fuel cell serves either for charging the traction battery or directly for driving. This realizes an arrangement for increasing the range, which arrangement is referred to as a "range extender". In both vehicles, the electrical energy is converted to high voltages and then fed into the high-voltage grid.Disclosure of the InventionIt is the object of the invention to provide an electrically operated vehicle of the type mentioned at the beginning which enables a long range more efficiently even at low temperatures.According to the invention, the object is achieved in that the low-voltage on-board electrical system can be supplied with low-voltage energy from the fuel cell. The arrangement according to the invention has the advantage that the electrical energy from the fuel cell is not fed into the high-voltage battery and does not have to be converted from a low-voltage level to a high-voltage level. This prevents energy losses during the conversion. The electrical energy is directly available to the electrical loads in the low-voltage on-board electrical system and can thus cover the base load. This relieves the traction battery operated with high voltage. The low voltage vehicle electrical system draws less energy from the high voltage battery. In this case, too, conversion losses are avoided. By using the energy from the fuel cell more effectively, the range can be increased significantly without feeding energy into the high-voltage battery (traction battery).The feeding of the electrical energy into the low-voltage on-board electrical system is also particularly advantageous because no safety-relevant high-voltage components of the vehicle have to be changed. In contrast to the high-voltage power supply system of the vehicle, the low-voltage on-board power supply system is comparatively easily accessible. The fuel cell can therefore be installed permanently subsequently or retrofitted as a module in a simple manner.Typically, the low-voltage on-board electrical system comprises a low-voltage battery. The low-voltage battery is provided in addition to the traction battery. The energy of the low-voltage battery is also available when the fuel cell is switched off.In a particularly preferred embodiment of the invention, it is provided that the low-voltage energy can be fed from the fuel cell into the low-voltage on-board electrical system at a voltage which is above the voltage of the low-voltage on-board electrical system. This can be realized with a suitable DC / DC converter. The low-voltage consumers connected to the low-voltage on-board electrical system are then preferably supplied with energy from the fuel cell. The high-voltage battery, which is likewise connected to the low-voltage on-board electrical system via a converter, is only subjected to load if the power requirement cannot be met by the fuel cell.The low voltage electrical system may typically have a voltage of 12 volts, 24 volts, or 48 volts or another voltage up to 60 volts in operation. The low-voltage energy from the fuel cell can then be fed into the low-voltage electrical system at a voltage difference of 0.01 to 5 volts above the voltage of the low-voltage electrical system. In a 12 volt low-voltage vehicle electrical system, for example, the voltage of the fuel cell can be converted to 14.5 volts. The output voltage of the fuel cell, i.e. the voltage optionally converted by a converter, with which the energy is fed into the low-voltage on-board electrical system, is then always above the voltage of the low-voltage on-board electrical system even in the case of minor fluctuations.Merely by reducing or avoiding the conversion losses in a converter when feeding in and using electrical power, a considerable extension of the range can be achieved. A range extension beyond this can be achieved if an additional electrical low-voltage heating for heating the high-voltage vehicle battery and / or other vehicle devices is provided, which can be supplied at least partially with electrical energy from the fuel cell. Typically, vehicles have electrically operated PTC heaters that are operated at high voltage. An additional heating that can be operated with low voltage makes it possible to provide additional thermal energy beyond the thermal energy of the fuel cell for heating the vehicle components, in particular the high-voltage battery and the passenger compartment. This is particularly advantageous at very low temperatures. Unlike in known arrangements, in this embodiment of the invention no energy is fed into the high voltage battery. Rather, as much energy as possible from the fuel cell is used for heating. The relief of the high-voltage battery achieved as a result leads to a significantly longer range.The thermal energy can be transmitted directly from the fuel cell to the high-voltage battery or indirectly, for example via an energy bus. In a preferred embodiment of the invention, a heating and cooling circuit with a heat exchanger fluid is provided for influencing the temperature of the high-voltage battery, of the passenger compartment and / or of other vehicle devices, and the thermal energy of the fuel cell and / or of an additional electrical low-voltage heating can be fed into the heating and cooling circuit. The heat exchanger fluid may be water, optionally with an antifreeze. However, it is also possible to realize the heating and cooling circuit with other liquids, air or other gases. Pumps, fans and other circulation means may be used. It may also be useful to construct the heating and cooling circuit from a plurality of sub-circuits which, for example, divide thermal energy among one another using heat exchanger devices. Alternatively, instead of a circuit, in particular when using air as heat exchanger fluid, a simple air flow can also be used, which transfers thermal energy and then flows into the atmosphere.A particularly preferred embodiment of the invention provides that the thermal energy of the fuel cell can be fed into the heating and cooling circuit upstream of the high-voltage heating. This can be done by a heat exchanger. This achieves a reduction in the electric power required for heat maintenance of the vehicle. In this embodiment, the high-voltage heating can be completely shut off or operates at a reduced load.In a further embodiment of the invention, it is provided that the heating and cooling circuit comprises a heat pump with an expansion valve, an evaporator and a compressor and the thermal energy of the fuel cell can be fed in downstream of the expansion valve or upstream of the compressor. This enables the increase of the refrigerant enthalpy and the improvement of the flow utilization in the heat pump.The vehicle typically has a high-voltage heater, for example a PTC heater. It is then particularly advantageous if the thermal energy of the fuel cell can be fed in upstream of the high-voltage heating. The heat is thus ideally incorporated into the heating and cooling circuit of the vehicle before the internal heating already present in the vehicle. This achieves a more rapid heating of the vehicle and its components, such as the traction battery, the motor, the inverter, and the like, during the cold start. The more rapid heating enables the switching-on duration of the high-voltage heating to be reduced.The thermal energy may be transferred to the HVAC heating and cooling circuit via a heat exchanger. However, it is also possible to transmit the thermal energy of the fuel cell separately via an air stream. In particular, it can be provided that a separate air stream comprises a heat pump with an evaporator and the thermal energy of the fuel cell and / or of a low-voltage heater operated with electrical energy of the fuel cell can be transmitted via the air stream to the evaporator, the high-voltage battery, the heating and cooling circuit or to other components with heat requirement. In this embodiment of the invention, the waste heat of the air-cooled fuel cell is used in that the heat is not directly incorporated into the HVAC heating and cooling circuit, but rather the warm exhaust air in vehicles with a heat pump is conducted in a targeted manner to the evaporator of the heat pump or to other components with heat requirement, for example the high-voltage battery or heating circuit components. In this embodiment of the invention, an improvement in the COP value (coefficient of performance) is achieved. The variant is particularly simple to integrate into an existing vehicle.The control of the fuel cell, the heating and cooling circuit, an air flow, the low-voltage battery and the further components can be effected by means of the control devices present in the vehicle. This is particularly useful if the components are already integrated during the production of the vehicle. If the vehicle is retrofitted, it is advantageous if an additional control is provided, with which the fuel cell and / or the energy flows of the electrical and thermal energy generated by the fuel cell can be controlled in accordance with the ambient temperature or a value representing the temperature of the high-voltage vehicle battery. In particular, it can also be provided that the additional controller controls the low-voltage heating. In this embodiment of the invention, the existing vehicle system and the existing controller do not have to be accessed. The control system is directed to the temperatures, for example the temperatures in the high-voltage battery, in the vehicle interior and / or the ambient temperatures. These can be evaluated in the controller and the fuel cell, optionally the low-voltage heating system and the parameters of the heating and cooling circuit can be set in such a way that the optimum operating temperatures of the high-voltage battery are achieved at high energy efficiency.Advantageously, the sensors are provided for determining the power fed from the high-voltage battery into the low-voltage on-board electrical system, and the controller switches on the fuel cell if the voltage measured for the feed is above a threshold value, in particular more than 1 volt above a quiescent voltage.Typically, a vehicle diagnostic system (OBD) is provided in the vehicles. In a particularly simple embodiment of the invention, the signals of the sensors can be transmitted at least partially via the vehicle diagnostic system to the additional controller. The data of the vehicle diagnostic system can be read out in a simple manner at a plug provided for this purpose. The signals make it possible to ascertain and identify the necessary heat requirement of the vehicle for the power output of the system as a function of the required thermal power in the heating and cooling circuit, e.g. HVAC. Alternatively or additionally, the current flow to at least one electrical load of the heating and cooling circuit can be measured. Ideally, the current to a plurality of consumers of the heating and cooling circuit is measured, for example by a heat pump, fan, water pump and / or air conditioning compressor. In order to optimize the demand recognition and determine the required power, the ambient temperature can also be used in particular.In an advantageous configuration of the invention, a DC / DC converter is provided between the fuel cell and the low-voltage on-board power supply system and / or a DC / DC converter is provided between the high-voltage battery and the low-voltage on-board power supply system, and at least one of the sensors is a current sensor which detects the current flow between the DC / DC converter and the low-voltage on-board power supply system. This enables the determination of the necessary current requirement of the vehicle for the power output of the system as a function of the required electrical power in the low-voltage network. Alternatively or additionally to reading out the OBD signals, the current requirement of the loads in the low-voltage on-board power supply can be identified by determining the current flow in the low-voltage on-board power supply between the DC / DC converter and the loads and / or the individual low-voltage loads and / or the current flow between the high-voltage power supply and the associated DC / DC converter.In particular at low temperatures, the vehicle including the fuel cell, unlike in internal combustion engines, must be prepared for starting. Thus, when the vehicle key is detected or a car door is opened, individual consumers are activated. This leads to a higher voltage in the low-voltage on-board power supply system, because the DC / DC converter feeds from the high-voltage power supply system into the low-voltage on-board power supply system. The additional controller is therefore preferably configured such that the fuel cell is started when a power determined from the signals of the current sensor at the DC / DC converter between the high-voltage battery and the low-voltage on-board power supply system exceeds a threshold value over a predefined period of time. Alternatively, a voltage gradient above a threshold value to be defined as a function of the vehicle can also be used as an indicator for the approaching vehicle start.Conversely, it can be provided that the controller is configured such that the fuel cell is switched off when a power determined from the signals of the current sensor falls below a threshold value over a predefined period of time. Typically, the vehicle controller turns all loads off in sequence. If a reasonable operation of the fuel cell system is undershot, i.e. if the electrical power falls below the threshold value for a defined period of time, the fuel cell is switched off. The fuel cell is therefore operated only when electrical and thermal power is actually also requested.In a further embodiment of the invention, it is provided that the controller is configured such that the fuel cell is no longer started for a predefined period of time after a predefined number of restarts. Normally, a restart of the fuel cell is possible immediately after it is switched off. However, if after a defined number of restarts the power decrease falls below a minimum each time, then a system start no longer takes place for a defined period of time.Known arrangements are based on the current requirement of the vehicle and its components. In contrast, a preferred embodiment of the invention provides that one of the sensors is a temperature sensor for detecting the ambient temperature and the controller determines a need for thermal energy from the ambient temperature. The sensor can be used to determine the necessary heat requirement of the vehicle and its components for the power output of the fuel cell as a function of the required thermal power in the heating and cooling circuit. In this case, the identification of the heat requirement can be determined by reading out the OBD signals and / or by measuring the current flow to at least one electrical load of the heating and cooling circuit. The flow of current to a plurality of consumers of the heating and cooling circuit, for example to the heat pump, to the fan, to the water pump and / or to the air conditioning compressor, is preferably detected. For optimizing requirement recognition and thus for ascertaining the power requirement, the ambient temperature can also be used.The invention can be realized by fixedly installing the fuel cell and, if appropriate, the low-voltage battery in a new car. In a further embodiment of the invention, a retrofit module is provided. The retrofit module can be used for retrofitting an electrically operated vehicle which is equipped with an electric drive for moving the vehicle, an electrically rechargeable high-voltage vehicle battery for supplying the electric drive and a low-voltage on-board electrical system for supplying further electrical low-voltage consumers. In this case, the retrofit module contains, according to the invention, a fuel cell which generates low-voltage electrical energy, with which the low-voltage on-board electrical system can be supplied. The fuel cell also generates thermal energy, with which the high-voltage vehicle battery can be heated directly or indirectly, for example via a heating and cooling circuit.A method according to the invention for operating a vehicle of the type described above comprises the steps of: (a) generating low-voltage electrical energy with the fuel cell; (b) storing the electrical energy in the low-voltage battery; (c) determining the state of charge of the high-voltage battery; and (d) feeding electrical energy from the low-voltage on-board electrical system to the high-voltage battery if the state of charge of the high-voltage battery falls below a threshold value.With the invention, a retrofit module can be used as an emergency power unit. In this case, if necessary, for example when the high-voltage battery reaches a state of charge at which the vehicle can no longer start, electrical energy can be fed from the low-voltage on-board electrical system into the high-voltage battery. The energy from the low voltage electrical system may be fed either from the fuel cell or from a low voltage battery charged with the fuel cell.Preferably, it is provided that(a) monitoring the state of charge of the low voltage battery; (b) turning on the fuel cell when the state of charge of the low voltage battery falls below a threshold; and (c) supplying the electrical energy generated with the fuel cell to the low voltage battery until the state of charge is again above the threshold.In this operating mode, at least the low-voltage battery always has sufficient electrical energy to realize essential functions in the vehicle. The operating mode can be used, for example, for emergency running at low speed. In this case, the feeding into the high-voltage network or into the charging interface of the drive battery takes place during travel. The charging interface is arranged, for example, before or after the drive battery.The operating mode can also be used for functioning as an emergency power unit (mobile charger). Electrical energy for the emergency driving mode is then provided by the feed via the charging interface at standstill. The operating mode can bridge long standstill phases without the energy stores of the vehicle being emptied completely.In particular, it can be provided that the fuel cell is switched on when the temperature of the high-voltage battery is below a threshold value. When the vehicle is at a standstill, the low-current battery can be monitored, for example. When the state of charge falls below a minimum threshold, the fuel cell is turned on and generates charging current for charging the low voltage battery. This electrical energy can be used to activate the control units in the vehicle. These include, for example, the release of the parking brake or the opening of doors.There may be cases where the voltage is so low that low voltage loads in the vehicle are shut down. The activation energy of the fuel cell system is comparatively low. For such cases, it may be provided that the fuel cell is started manually for charging the low-voltage battery.The fuel cell can also serve for generating a trickle charge. This is used when the vehicle is standing in the cold in winter, for example, and the high-voltage battery is completely discharged. Such a situation can occur with prolonged service lives at low temperatures. The waste heat of the fuel cell is then additionally used for the vehicle.The fuel cell makes it possible to protect the vehicle battery from critical temperatures. Its use prevents the battery from being subcooled, for example by activation of the circulation pump responsible for cooling / heating.Embodiments of the invention are the subject of the dependent claims. An exemplary embodiment is explained in more detail below with reference to the attached drawings.DefinitionsIn this description and in the appended claims, all terms have a meaning familiar to the person skilled in the art which is set forth in the technical literature, standards and the relevant websites and publications, in particular of the lexical type, for example www.Wikipedia.de www.wart.de or the competitor, research institute, universities and associations. In particular, the terms used do not have the opposite meaning of what the person skilled in the art takes from the above publications.Brief Description of the DrawingsFIG. 1 is a schematic illustration of a vehicle to illustrate the installation variants of a fuel cell module. FIG. 2 is a perspective view of a fuel cell module with a housing and pressure vessels for hydrogen. FIG. 3 is a schematic illustration of the circuits for mobile application of the arrangement of FIG. 2. FIG. 4 shows a variant of the exemplary embodiment from FIG. 3 with an additional low-voltage battery. FIG. 5 illustrates the introduction of the heat and waste heat from the retrofit module with fuel cell into the heating and cooling circuit of the vehicle. FIG. 6 shows a heat pump of the vehicle, which heat pump is subjected to heat and waste heat from the retrofit module.DESCRIPTION OF THE EMBODIMENTFIG. 1 shows a vehicle generally designated 10. In the present exemplary embodiment, the vehicle 10 is a passenger motor vehicle. It is understood that the invention can also be applied to any other vehicle, i.e. trucks, recreational vehicles, sailboats, ships, aircraft, motor cycles and the like. The vehicle has a cavity at the rear or front, such as a trunk compartment 12 or 18, respectively. In the trunk compartment 12 or 18, the vehicle can be retrofitted with a fuel cell module 14 or it can already be installed in a fixed manner during production. The fuel cell module 14 is supplied with hydrogen from a tank 16 via a feed line 20.FIG. 2 shows the fuel cell module 14 and the tank 16 in detail. In the present exemplary embodiment, the tank 16 comprises two pressure vessels 22 each having a volume of, for example, 10 l and, for example, 350 bar or 700 bar, which are filled with liquid hydrogen. Depending on the fuel cell, it is of course also possible to use other gases or liquids in more or fewer pressure vessels 22.The pressure vessels 22 are secured bottle-shaped and crash-proof on a common base plate 24. For this purpose, tensioning straps 26 are provided. The base plate 24 may be fixedly bolted or otherwise fixed in the vehicle prior to the pressure vessels 22 being secured. This facilitates the installation of the base plate 24. the tightening straps 26 can also be operated by the layman, so that the pressure vessels 22 can easily be released and replaced, serviced and / or filled as required.The supply line 20 to the fuel cell module 14 is provided on the module side with a manually operated shut-off 28. Upstream of the shut-off 28, T-pieces 30 and 34 and a corner piece 32 are installed in the supply line 20, respectively. A first pressure vessel 22 is connected via the T-piece 30. It is understood that further pressure vessels can likewise be connected via further T-pieces. A further pressure vessel is connected to the corner piece 32. If only one pressure vessel 22 is provided, no tee 30 is required. It is understood that instead of a corner piece 32, a linear connection is also possible.A filling connection 36 with a valve opening in the direction of the feed line is connected to the T-piece 34. Via the filling connection 36, the pressure vessels 22 can be filled and refilled with the shut-off 28 closed. Instead of filling the pressure vessels 22 via the filling connection 36, empty pressure vessels 22 can also be replaced by full pressure vessels. For this purpose, a quick connection 38 is opened and the clamping straps 26 are released. The quick connection 38 can be designed, for example, similar to commercially available quick connections for hoses from garden engineering, in which the opening in the pressure vessel 22 is closed by a valve as soon as the quick connection 38 is released. It is understood that any other terminal may be used.The use of replaceable pressure vessels 22 allows the use of a deposit system, so that not every gas station needs to provide the required fuel at a fuel dispenser. In an alternative exemplary embodiment, the tank 16 is fixedly integrated into the fuel cell module 14 and is housed together therewith. Then only one connection piece is accessible from the outside for filling. The fuel cell module 14 is then somewhat larger, but easier to install.The retrofit module comprising fuel cell 14, tank 16 and the further components described below is identified in FIGS. 3 to 6 by a dashed line 104. All remaining components are typical components that are incorporated in the manufacture of conventional electrically powered vehicles 10.In operation, the fuel cell 14 generates electrical energy. This is illustrated at 100 in FIGS. 3 and 4. The fuel cell 14 also generates thermal energy. This is illustrated by an arrow 102. The electrical energy is fed via a DC / DC converter 106 into the already present low-voltage on-board electrical system 108. An additional low voltage PTC heater 110 is connected to the fuel cell 14 upstream of the DC / DC converter 106. This generates additional thermal energy beyond the thermal energy from the fuel cell if necessary. This is illustrated by an arrow 112. Both the thermal energy 102 from the fuel cell 14, i.e. the waste heat thereof, and the thermal energy 112 generated by the PTC heater 110 are emitted via a heat exchanger to the already present heating and cooling circuit (HVAC) 120 of the vehicle 10.The vehicle 10 has a low-voltage on-board electrical system 108 to which a plurality of low-voltage electrical loads 114 are connected. These consumers include control units, light, comfort devices, window, seat and steering wheel heating, entertainment devices and smaller drives for moving mirrors and the like. Low-voltage loads 116 are also connected, which are required for thermal management. These include, for example, pumps, fans and heaters. Excess low voltage energy may be stored in a low voltage battery 118 and is available back to the low voltage grid as needed.In addition to the low-voltage on-board electrical system 108, the vehicle 10 also has a high-voltage electrical system 122. The voltage in the high-voltage grid 122 is many times higher than the voltage in the low-voltage on-board grid 108. For example, the low-voltage on-board power supply system can be operated at 12 volts. The voltage in the high-voltage power supply system is significantly above 200 volts, for example 400 volts. The high voltage power supply is powered from a high voltage rechargeable battery 124 (also referred to as an accumulator). For example, the high voltage battery 124 may be a lithium ion battery. The high-voltage battery 124 covers the demand for electrical energy of the drive unit 126, i.e. of an electric motor. In addition to the drive unit 126, other high-voltage consumers 128 can also be connected to the high-voltage network, for example a compressor in the heating and cooling circuit 120, a heat pump or a high-voltage PTC heater. These components are typically already present in the vehicle 10 before retrofitting. Typically, the vehicles provide a DC / DC converter 130, via which electrical energy from the high voltage battery 124 may be provided to the low voltage electrical system 108.The fuel cell 14 now represents a second energy source, with which low-voltage energy is fed into the low-voltage on-board electrical system 108 at 132. The voltage from the fuel cell 14 is converted with the DC / DC converter 106 to a voltage level that is slightly above the voltage generated by the DC / DC converter 130 from the high voltage battery 124. Therefore, the electrical energy from the fuel cell 14 is always used first. This protects the high-voltage battery and achieves a high range.The fuel cell 14 thus generates thermal energy, on the one hand, with which vehicle components, in particular the high-voltage battery 124, can be heated. This improves the range. Secondly, it is achieved that less energy is drawn from the high-voltage battery 124 for the low-voltage on-board electrical system. This also improves the range.The retrofit module 104 is provided with an additional controller 134. The controller 134 is used to control the fuel cell 14 and the low-voltage heater 110. The switching on and off of these components 14 and 110 is carried out in accordance with sensor signals. The sensor signals, in particular the ambient temperature, are read out from the OBD plug 136. In the present exemplary embodiment, however, further sensors 138 are also provided in the retrofit module 104. One of the sensors is a current sensor 146 for measuring current between DC / DC converter 130 and low-voltage vehicle electrical system 108, and a current sensor 147 between DC / DC converter 106 and low-voltage vehicle electrical system 108. When the vehicle 10 is switched on, the electrical loads 114 are gradually switched on. In this case, the voltage measured by a sensor U normally falls. The vehicle's own controller therefore provides that the voltage in the low-voltage on-board electrical system is raised somewhat before the low-voltage loads 114 are switched on. For this purpose, a trigger is used, for example the approach of the vehicle key or the opening of a vehicle door. Depending on the current and / or voltage profile, the controller 134 interprets that the vehicle 10 is in short in need of electrical and / or thermal energy and switches on the fuel cell 14.The sensors 147 and 148 shown in FIGS. 3 and 4 are provided for determining the power fed into the low-voltage on-board electrical system from the high-voltage battery. The controller switches on the fuel cell if the voltage measured for the feed at the sensor 148 is above a threshold value, in particular more than 1 volt above a quiescent voltage. If desired, the retrofit module 104 includes an additional low voltage battery 150. This is illustrated in FIG. 4.The exemplary embodiment in FIG. 5 illustrates a variant in which the thermal energy of the fuel cell 14 can be fed into the heating and cooling circuit 120 upstream at 302 to the high-voltage heater 128 via a heat exchanger 301. The temperatures in the retrofit module and in the heating and cooling circuit 120 are detected by sensors 141, 142 and 143. This achieves a reduction in the electric power required for heat maintenance of the vehicle. In this embodiment, the high-voltage heating can be completely shut off or operates at a reduced load.FIG. 6 illustrates an embodiment in which the heating and cooling circuit comprises a heat pump 200 with a condenser 212, an expansion valve 213, an evaporator 215 and a compressor 211, and the thermal energy of the fuel cell is fed downstream of the expansion valve 213 or upstream of the compressor ( 211). In this case, the thermal energy of the fuel cell is added to the lines 214 and 216 and to the evaporator 215. This enables the increase of the refrigerant enthalpy and the improvement of the flow utilization in the heat pump.The exemplary embodiments explained above serve to illustrate the invention claimed in the claims. Features disclosed together with other features can generally also be used alone or in combination with other features explicitly or implicitly disclosed in the exemplary embodiments in the text or in the drawings. Dimensions and sizes are given only by way of example. Suitable ranges will be apparent to those skilled in the art and therefore need not be explained in more detail here. The disclosure of a specific configuration of a feature does not mean that the invention is intended to be limited to this specific configuration. Rather, such a feature can be realized by a large number of other configurations familiar to the skilled person. The invention can therefore be realized not only in the form of the illustrated embodiments, but by all embodiments which are covered by the scope of the appended claims.The terms "upper", "lower", "right" and "left" refer solely to the appended drawings. It is to be understood that claimed devices may also assume a different orientation. The term "containing" and the term "comprising" mean that further, non-mentioned components can be provided. The term "substantially", "predominantly" and "predominantly" includes all features which have a property or content predominantly, i.e. more than all other mentioned components or properties of the feature, that is to say, for example more than 50% in the case of two components.References 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 2011 076 737 A1

[0008] DE 10 2017 002 854 A1

[0008] Cited Non-Patent Literaturewww.Wikipedia.de

[0039] www.wis. de

[0039]

Claims

Electrically operated vehicle (10), containing (a) an electric drive (126) for moving the vehicle (10); (b) a fuel cell (14) for generating electrical and thermal energy; (c) an electrically rechargeable high-voltage vehicle battery (124) for supplying the electric drive (126), which battery can be heated with thermal energy of the fuel cell (14); and (d) a low-voltage electrical system (108) for supplying further electrical low-voltage consumers (114); characterized in that (e) the low-voltage electrical system (108) can be supplied with low-voltage energy from the fuel cell (14).Vehicle according to one of the preceding claims, characterized in that the low-voltage energy can be fed from the fuel cell (14) into the low-voltage on-board electrical system (108) at a voltage which is above the voltage of the low-voltage on-board electrical system.The vehicle of any preceding claim, characterized in that the low voltage electrical system (108) is in operation at a voltage of 12 volts, 24 volts or 48 volts or another voltage up to 60 volts.Vehicle according to Claim 2 or 3, characterized in that the low-voltage energy can be fed from the fuel cell (14) into the low-voltage electrical system at a voltage difference of 0.01 to 5 volts above the voltage of the low-voltage electrical system (108).Vehicle according to one of the preceding claims, characterized in that an additional electrical low-voltage heating (110) is provided for heating the high-voltage vehicle battery (124) and / or other vehicle devices, which can be supplied at least partially with electrical energy from the fuel cell (14).Vehicle according to one of the preceding claims, characterized in that a heating and cooling circuit (120) with a heat exchanger fluid is provided for influencing the temperature of the high-voltage battery (124), of the passenger compartment and / or of other vehicle devices, and the thermal energy of the fuel cell (14) and / or of an additional electrical low-voltage heater (110) can be fed into the heating and cooling circuit (120).Vehicle according to Claims 5 and 6, characterized in that the thermal energy of the fuel cell (14) can be fed into the heating and cooling circuit (120) upstream of the high-voltage heater (110).Vehicle according to Claim 6 or 7, characterized in that the heating and cooling circuit (120) comprises a heat pump (200) having an expansion valve (213), an evaporator (215), a condenser (212) and a compressor (211), and the thermal energy of the fuel cell (14) and / or of the heating element (110) can be fed in downstream of the expansion valve (213) or upstream of the compressor (211).Vehicle according to one of Claims 6 to 8, characterized in that the vehicle has a high-voltage heater (128) and the thermal energy of the fuel cell (14) and of the heating element (110) can be fed in upstream of the high-voltage heater (128).Vehicle according to one of the preceding claims 6 to 8, characterized in that thermal energy of the fuel cell (14) can be transmitted to the heating and cooling circuit (120) via an air stream.Vehicle according to Claim 10, characterized in that the heating and cooling circuit (120) comprises a heat pump with an evaporator and the thermal energy of the fuel cell (14) and / or of a low-voltage heater (110) operated with electrical energy of the fuel cell can be transmitted via the air stream to the evaporator, the high-voltage battery (124), the heating and cooling circuit (120) or to other components with heat requirement.Vehicle according to one of the preceding claims, characterized in that an additional controller (134) is provided, with which the fuel cell (14) and / or the energy flows of the electrical and thermal energy generated by the fuel cell can be controlled in accordance with the ambient temperature or a value representing the temperature of the high-voltage vehicle battery (124).The vehicle of claim 12, characterized in that the additional controller (134) controls the low voltage heater (110).Vehicle according to Claim 13, characterized in that sensors (138) are provided for determining the power fed into the low-voltage on-board electrical system (108) by the high-voltage battery (124), and the controller switches on the fuel cell (14) if the voltage measured for the feed is above a threshold value, in particular more than 1 volt above a quiescent voltage.Vehicle according to Claim 14, characterized in that a vehicle diagnostic system (OBD) (136) is provided and the signals of the sensors can be transmitted at least partially via the vehicle diagnostic system (136) to the additional controller (134).Vehicle according to claim 14, characterised in that a DC / DC converter (106) is provided between the fuel cell (14) and the low-voltage on-board power supply system (108), and / or a DC / DC converter (130) is provided between the high-voltage battery (124) and the low-voltage on-board power supply system (108), and at least one of the sensors (138) is a current sensor which detects the current flow between the DC / DC converter (106, 130) and the low-voltage on-board power supply system (108).Vehicle according to Claim 16, characterized in that the controller (134) is configured in such a way that the fuel cell (14) is started if a power determined from the signals of the current sensor (147) at the DC / DC converter between the high-voltage battery (124) and the low-voltage on-board electrical system (108) exceeds a threshold value over a predefined period of time.Vehicle according to Claim 16 or 17, characterized in that the controller (134) is set up in such a way that the fuel cell (14) is switched off if a power determined from the signals of the current sensor (147) falls below a threshold value over a predefined period of time.Vehicle according to Claim 18, characterized in that the controller (134) is configured in such a way that the fuel cell (14) is no longer started for a predefined period after a predefined number of restarts.Vehicle according to one of Claims 14 to 19, characterized in that one of the sensors (138) is a temperature sensor for detecting the ambient temperature and the controller determines a need for thermal energy from the ambient temperature.Retrofit module for retrofitting an electrically operated vehicle, having an electric drive (126) for moving the vehicle (10), an electrically rechargeable high-voltage vehicle battery (124) for supplying the electric drive (126), and a low-voltage on-board electrical system (108) for supplying further electrical low-voltage consumers (114); wherein the retrofit module contains a fuel cell (14) which generates low-voltage electrical energy with which the low-voltage on-board electrical system (108) can be supplied and thermal energy with which the high-voltage vehicle battery (124) can be heated.Retrofit module according to Claim 21, characterized in that a low-voltage battery (118) is included, which can be integrated into the low-voltage on-board electrical system (108).Method for operating a vehicle (10) according to one of Claims 2 to 20, having the steps of: (a) generating low-voltage electrical energy with the fuel cell (14); (b) storing the electrical energy in the low-voltage battery (118); (c) determining the state of charge of the high-voltage battery (124); and (d) feeding electrical energy from the low-voltage on-board power supply system (108) into the high-voltage battery (124) via a charging power supply connection if the state of charge of the high-voltage battery falls below a threshold value.Method according to Claim 23, characterized in that (a) the state of charge of the low-voltage battery (118) is monitored; (b) the fuel cell (14) is switched on if the state of charge of the low-voltage battery (118) falls below a threshold value; and (c) the electrical energy generated by the fuel cell (14) is fed into the low-voltage battery (118) until the state of charge is again above the threshold value.Method according to Claim 24, characterized in that the fuel cell (14) is switched on if the temperature of the high-voltage battery (124) is below a threshold value.

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