Electrically powered vehicle

Abstract

The invention relates to an electrically powered vehicle (10), including 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 power to the electric drive (126), which battery can be heated by thermal energy of the fuel cell (14); and a low-voltage electrical system (108) for supplying other electric low-voltage consumers (114); the invention is characterised in that the low-voltage electrical system (108) can be supplied with low-voltage power from the fuel cell (14).

Description

[0001] International patent application

[0002] Electric vehicle

[0003] Technical area

[0004] The invention relates to an electrically powered vehicle comprising

[0005] (a) an electric drive for propulsion of the vehicle;

[0006] (b) a fuel cell for generating electrical and thermal energy;

[0007] (c) an electrically rechargeable high-voltage vehicle battery for supplying the electric drive, which can be heated with thermal energy from the fuel cell; and

[0008] (d) a low-voltage on-board network to supply additional low-voltage electrical consumers.

[0009] The invention further relates to a retrofit module for retrofitting and a method for operating such an electrically powered vehicle.

[0010] A vehicle can be moved on land, water, or air. In particular, a vehicle can be a passenger car, truck, mobile home, sailboat, ship, airplane, motorcycle, and the like.

[0011] In the past, most vehicles were powered by fossil fuels, for example in an internal combustion engine. Other solutions are now being sought to achieve climate neutrality. In particular, vehicles with electric drive and a powerful vehicle battery are already available as standard. Drives with fuel cells are also known. In internal combustion engines, the energy stored chemically 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 into mechanical work via an electric drive. In a fuel cell, the energy stored chemically in a fuel, for example hydrogen, is converted directly into electrical energy and then into mechanical work.

[0012] In addition to these drive systems, there are also hybrid systems, also known as hybrid drives. These utilize a conventional combustion engine and an additional electric drive system with a battery as an energy storage device. As long as the battery is supplying power, the vehicle is driven exclusively by electrical energy. After that, the combustion engine serves as the primary drive. Depending on the design, the battery can be recharged through recuperation or, in the case of plug-in hybrids, from external energy sources. Hybrid drives utilize two primary drives and two associated energy storage systems—a battery and a fuel tank. These systems are complex and heavy, thus increasing manufacturing costs, maintenance effort, and energy consumption.

[0013] The disadvantages of purely electric vehicles are their limited range, the long charging time, and the short battery life. These adverse effects are more pronounced at low temperatures, particularly in cold regions, at night, and in winter. At low temperatures, battery efficiency decreases. This makes it necessary to heat the battery. The heating is powered by energy from the vehicle battery. The same applies to the passenger compartment, which also requires electrical heating. This reduces the vehicle's range.

[0014] State of the art

[0015] DE 10 2011 076 737 A1 and DE 10 2017 002 854 A1 each disclose an electrically powered vehicle in which the traction battery is thermally coupled to an additional fuel cell. The thermal coupling can occur directly through spatial proximity or indirectly via a thermal energy management system, such as a heating and cooling circuit. The electrical energy generated by the fuel cell is used either to charge the traction battery or directly for propulsion. This creates a range-increasing arrangement known as a "range extender." In both vehicles, the electrical energy is converted to high voltages and then fed into the high-voltage grid.

[0016] Disclosure of the invention

[0017] The object of the invention is to create an electrically powered vehicle of the type mentioned above which enables a long range more efficiently even at low temperatures.

[0018] According to the invention, this object is achieved in that the low-voltage 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 avoids energy losses during conversion. The electrical energy is directly available to the electrical consumers in the low-voltage electrical system and can thus cover the base load. This relieves the load on the high-voltage traction battery. The low-voltage electrical system draws less energy from the high-voltage battery. This also avoids conversion losses. Through the more effective use of the energy from the fuel cell, the range can be significantly increased without feeding energy into the high-voltage battery (traction battery).

[0019] Feeding the electrical energy into the low-voltage on-board network is particularly advantageous because no safety-relevant

[0020] High-voltage components of the vehicle must be modified. In contrast to the vehicle's high-voltage system, the low-voltage electrical system is comparatively easy to access. The fuel cell can therefore be easily retrofitted as a permanent installation or as a module. The low-voltage electrical system typically includes a low-voltage battery. The low-voltage battery is provided in addition to the traction battery. The energy from the low-voltage battery is available even when the fuel cell is switched off.

[0021] In a particularly preferred embodiment of the invention, the low-voltage energy from the fuel cell can be fed into the low-voltage vehicle electrical system at a voltage that is higher than the voltage of the low-voltage vehicle electrical system. This can be achieved using a suitable DC / DC converter. The low-voltage consumers connected to the low-voltage vehicle electrical system are then preferably supplied with energy from the fuel cell. The high-voltage battery, which is also connected to the low-voltage vehicle electrical system via a converter, is only loaded when the power demand cannot be met by the fuel cell.

[0022] The low-voltage electrical system can typically operate at a voltage of 12 volts, 24 volts, or 48 volts, or another voltage up to 60 volts. The low-voltage energy from the fuel cell can then be fed into the low-voltage electrical system with a voltage difference of 0.01 to 5 volts above the voltage of the low-voltage electrical system. In a 12-volt low-voltage electrical system, for example, the voltage of the fuel cell can be converted to 14.5 volts. The output voltage of the fuel cell—that is, the voltage (converted, if necessary, by a converter) at which the energy is fed into the low-voltage electrical system—is then always above the voltage of the low-voltage electrical system, even with minor fluctuations.

[0023] A significant range extension can be achieved simply by reducing or avoiding the conversion losses in a converter when feeding in and using electrical power. A further range extension can be achieved if an additional low-voltage electrical heater is provided to heat the high-voltage vehicle battery and / or other vehicle equipment, which can be at least partially supplied with electrical energy from the fuel cell. Vehicles typically have electrically operated PTC heaters that are operated at high voltage. An additional heater that can be operated at low voltage makes it possible to provide additional thermal energy for heating the vehicle components, in particular the high-voltage battery and the passenger compartment, in addition to the thermal energy of the fuel cell. This is particularly advantageous at very low temperatures.Unlike known arrangements, this embodiment of the invention does not feed any energy into the high-voltage battery. Instead, as much energy as possible from the fuel cell is used for heating. The resulting reduction in the load on the high-voltage battery leads to a significantly increased range.

[0024] The thermal energy can be transferred 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, the passenger compartment, and / or other vehicle equipment. The thermal energy of the fuel cell and / or an additional low-voltage electric heater can be fed into the heating and cooling circuit. The heat exchanger fluid can be water, possibly with an antifreeze. However, it is also possible to implement the heating and cooling circuit with other liquids, air, or other gases. Pumps, fans, and other circulation devices can be used.It may also be useful to construct the heating and cooling circuit from several sub-circuits, which, for example, share thermal energy among themselves using heat exchangers. Alternatively, instead of a circuit, especially when using air as the heat exchange fluid, a simple air flow can be used, which transfers thermal energy and then flows into the atmosphere.

[0025] 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 heater. This can be achieved through a heat exchanger. This reduces the electrical power required to maintain the vehicle's heat. In this embodiment, the high-voltage heater can be switched off completely or operates at a reduced load. In a further embodiment of the invention, 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 downstream of the expansion valve or upstream of the compressor. This enables the refrigerant enthalpy to be increased and the electricity utilization in the heat pump to be improved.

[0026] Typically, the vehicle has a high-voltage heater, such as a PTC heater. In this case, it is particularly advantageous if the thermal energy from the fuel cell can be fed upstream of the high-voltage heater. The heat is therefore ideally integrated into the vehicle's heating and cooling circuit upstream of the vehicle's existing internal heater. This allows for faster warm-up of the vehicle and its components, such as the traction battery, motor, inverter, and the like, during cold starts. This faster warm-up allows for a reduction in the high-voltage heater's duty cycle.

[0027] The thermal energy can be transferred to the HV AC heating and cooling circuit via a heat exchanger. However, it is also possible to transfer the thermal energy of the fuel cell separately via an air flow. In particular, it can be provided that the separate air flow comprises a heat pump with an evaporator, and the thermal energy of the fuel cell and / or a low-voltage heater powered by electrical energy from the fuel cell can be transferred via the air flow to the evaporator, the high-voltage battery, the heating and cooling circuit, or other components requiring heat.In this embodiment of the invention, the waste heat from the air-cooled fuel cell is utilized in that the heat is not incorporated directly into the HV AC heating and cooling circuit, but rather the warm exhaust air in vehicles with a heat pump is directed specifically to the evaporator of the heat pump or to other components that require heat, 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. This variant is particularly easy to integrate into an existing vehicle. The fuel cell, the heating and cooling circuit, an air flow, the low-voltage battery and the other components can be controlled using the control devices existing in the vehicle. This is particularly useful if the components are integrated during vehicle manufacture.If the vehicle is retrofitted, it is advantageous if an additional control system 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 according to 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 control system controls the low-voltage heating. With this embodiment of the invention, there is no need to intervene in the existing vehicle system and the existing control system. The control system is based on 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 control system and the fuel cell, if necessary.The low-voltage heater and the parameters of the heating and cooling circuit can be adjusted to achieve the optimal operating temperatures of the high-voltage battery with high energy efficiency.

[0028] Advantageously, the sensors are provided to determine the power fed into the low-voltage vehicle electrical system by the high-voltage battery, and the control system switches on the fuel cell when the voltage measured for the feed-in is above a threshold value, in particular more than 1 volt above a rest voltage.

[0029] Typically, vehicles are equipped with an on-board diagnostic system (OBD). In a particularly simple embodiment of the invention, the sensor signals can be transmitted, at least in part, to the additional controller via the vehicle diagnostic system. The data from the vehicle diagnostic system can be easily read out using a connector provided for this purpose. The signals enable the determination and identification of the vehicle's heat requirement for the system's power output, depending on the required thermal output in the heating and cooling circuit, e.g., HVAC. Alternatively or additionally, the current flow to at least one electrical consumer in the heating and cooling circuit can be measured. Ideally, the current flow to several consumers in the heating and cooling circuit is measured, e.g., by a heat pump, fan, water pump, and / or air conditioning compressor.The ambient temperature can also be used to optimise demand detection and determine the required power.

[0030] In an advantageous embodiment of the invention, a DC / DC converter is provided between the fuel cell and the low-voltage vehicle electrical system and / or a DC / DC converter is provided between the high-voltage battery and the low-voltage vehicle electrical system, and at least one of the sensors is a current sensor that detects the current flow between the DC / DC converter and the low-voltage vehicle electrical system. This makes it possible to determine the vehicle's necessary power consumption for the system's power output as a function of the required electrical power in the low-voltage vehicle electrical system. The power consumption of the consumers in the low-voltage vehicle electrical system can be identified as an alternative to or in addition to reading the OBD signals by determining the current flow in the low-voltage vehicle electrical system between the DC / DC converter and the consumers and / or the individual low-voltage consumers and / or the current flow between the high-voltage vehicle electrical system and the associated DC / DC converter.

[0031] Particularly at low temperatures, the vehicle, including the fuel cell, must be prepared for starting, unlike combustion engines. Therefore, 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 vehicle electrical system because the DC / DC converter feeds power from the high-voltage network into the low-voltage vehicle electrical system. The additional control is therefore preferably configured such that the fuel cell is started when the power determined from the signals of the current sensor on the DC / DC converter between the high-voltage battery and the low-voltage vehicle electrical system exceeds a threshold value over a specified period of time. Alternatively, a voltage gradient above a threshold value, which can be defined for each vehicle, can be used as an indicator of the impending vehicle start.Conversely, the control system can be configured such that the fuel cell is shut down if the power determined from the current sensor signals falls below a threshold for a specified period of time. Typically, the vehicle control system shuts down all consumers in sequence. If the fuel cell system falls below a reasonable level of operation, i.e., if the electrical power falls below the threshold for a defined period of time, the fuel cell is shut down. The fuel cell is therefore only operated when electrical and thermal power is actually being used.

[0032] In a further embodiment of the invention, the control system is configured such that, after a predetermined number of restarts, the fuel cell is not restarted for a predetermined period of time. Normally, the fuel cell can be restarted immediately after it is shut down. However, if, after a defined number of restarts, the power consumption falls below a minimum each time, the system will not restart for a defined period of time.

[0033] Known arrangements are based on the power requirements of the vehicle and its components. A preferred embodiment of the invention, however, provides that one of the sensors is a temperature sensor for detecting the ambient temperature, and the controller determines a thermal energy requirement 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. The heat requirement can be identified by reading the OBD signals and / or by measuring the current flow to at least one electrical consumer in the heating and cooling circuit. Preferably, the current flow to several consumers in the heating and cooling circuit, for example to the heat pump, the fan, the water pump, and / or the air conditioning compressor, is detected.The ambient temperature can also be used to optimize demand detection and thus determine the power requirement. The invention can be implemented by permanently installing the fuel cell and, if applicable, the low-voltage battery in a new car. A further embodiment of the invention provides a retrofit module. The retrofit module can be used to retrofit an electrically powered vehicle equipped with an electric drive for propulsion of the vehicle, an electrically rechargeable high-voltage vehicle battery for powering the electric drive, and a low-voltage on-board electrical system for supplying additional low-voltage electrical consumers. According to the invention, the retrofit module contains a fuel cell that generates low-voltage electrical energy that can be used to supply the low-voltage on-board electrical system.The fuel cell also generates thermal energy, which can be used to heat the high-voltage vehicle battery directly or indirectly, for example via a heating and cooling circuit.

[0034] A method according to the invention for operating a vehicle of the type described above comprises the steps:

[0035] (a) Determine the state of charge of the high-voltage battery;

[0036] (b) generating low-voltage electrical energy with the fuel cell;

[0037] (c) feeding the electrical energy into the low-voltage battery; and

[0038] (d) feeding electrical energy from the low-voltage vehicle electrical system into the high-voltage battery via a charging network connection when the state of charge of the high-voltage battery falls below a threshold value.

[0039] The invention allows a retrofit module to be used as an emergency power generator. If necessary, for example, if the high-voltage battery reaches a charge level at which the vehicle can no longer start, electrical energy from the low-voltage electrical system can be fed into the high-voltage battery. The energy from the low-voltage electrical system can be fed either from the fuel cell or from a low-voltage battery charged with the fuel cell.

[0040] Operation can be manual with driver intervention or automated without driver intervention.

[0041] Provision may be made for (a) the state of charge of the low-voltage battery to be monitored;

[0042] (b) the fuel cell is switched on when the charge level of the

[0043] Low voltage battery falls below a threshold; and

[0044] (c) the electrical energy generated by the fuel cell is transferred to the

[0045] low-voltage battery until the charge level is again above the threshold.

[0046] In this mode of operation, at least the low-voltage battery always has sufficient electrical energy to perform essential functions in the vehicle. This mode can, for example, be used to provide energy for emergency driving at low speeds. The energy is fed into the high-voltage grid or into the charging interface of the traction battery while driving. The charging interface can be located, for example, upstream or downstream of the traction battery.

[0047] This mode of operation can also be used as an emergency power generator (mobile charger). In this case, electrical energy for emergency driving is provided by feeding it in via the charging interface while the vehicle is stationary. This mode can bridge long periods of standstill without completely draining the vehicle's energy storage.

[0048] In particular, it can be provided that the fuel cell is switched on when the temperature of the high-voltage battery falls below a threshold. For example, when the vehicle is stationary, the low-current battery can be monitored. When the state of charge falls below a minimum threshold, the fuel cell is switched on and generates charging current to charge the low-voltage battery. This electrical energy can be used to activate the control units in the vehicle. This includes, for example, releasing the parking brake or opening doors.

[0049] There may be cases where the voltage is so low that low-voltage consumers in the vehicle are switched off. The activation energy of the fuel cell system is comparatively low. In such cases, the fuel cell can be started manually to charge the low-voltage battery. The fuel cell can also be used to generate a trickle charge. This is needed, for example, when the vehicle is parked in the cold in winter and the high-voltage battery is completely discharged. Such a situation can arise during extended periods of inactivity at low temperatures. In this case, the waste heat from the fuel cell is also used for the vehicle.

[0050] The fuel cell makes it possible to protect the vehicle battery from critical temperatures. Its use prevents the battery from overcooling, for example, by activating the circulation pump responsible for cooling / heating.

[0051] Embodiments of the invention are the subject of the dependent claims. One embodiment is explained in more detail below with reference to the accompanying drawings.

[0052] Definitions

[0053] In this description and the appended claims, all terms have a meaning familiar to the person skilled in the art, as defined in the specialist literature, standards, and relevant internet pages and publications, particularly lexical ones, such as www.Wikipedia.de, www.wissen.de, or those of competitors, research institutes, universities, and associations. In particular, the terms used do not have the opposite meaning to what the person skilled in the art would understand from the above publications.

[0054] Short description of the drawings

[0055] Fig. l is a schematic representation of a vehicle to illustrate the installation variants of a fuel cell module.

[0056] Figure 2 is a perspective view of a fuel cell module with a housing and pressure vessels for hydrogen. Figure 3 is a schematic representation of the circuits for the mobile application of the arrangement shown in Figure 2.

[0057] Fig.4 shows a variant of the embodiment of Figure 3 with an additional low-voltage battery.

[0058] Fig.5 illustrates the heat and waste heat input from the retrofit module with

[0059] Fuel cell in the heating and cooling circuit of the vehicle.

[0060] Fig.6 shows a heat and waste heat from the retrofit module

[0061] Vehicle heat pump.

[0062] Description of the embodiment

[0063] Figure 1 shows a vehicle generally designated 10. In the present embodiment, the vehicle 10 is a passenger car. It is understood that the invention can also be applied to any other vehicle, i.e., trucks, mobile homes, sailboats, ships, airplanes, motorcycles, and the like. The vehicle has a hollow space at the front or rear, such as a trunk 12 or 18, respectively. The vehicle can be retrofitted with a fuel cell module 14 in the trunk 12 or 18, or it can be permanently installed during manufacture. The fuel cell module 14 is supplied with hydrogen from a tank 16 via a supply line 20.

[0064] Figure 2 shows the fuel cell module 14 and the tank 16 in detail. In the present embodiment, the tank 16 comprises two pressure vessels 22, each with a volume of, for example, 10 l and a pressure of, for example, 350 bar or 700 bar, which are filled with liquid hydrogen. Depending on the fuel cell, other gases or liquids can of course also be used in more or fewer pressure vessels 22.

[0065] The pressure vessels 22 are bottle-shaped and mounted in a crash-proof manner on a common base plate 24. Tensioning straps 26 are provided for this purpose. The base plate 24 can be firmly screwed into the vehicle or secured in another way before the pressure vessels 22 are attached. This facilitates the installation of the base plate 24. The tensioning straps 26 can also be operated by a layperson, so that the pressure vessels 22 can be easily removed and replaced, maintained, and / or filled as needed.

[0066] The supply line 20 to the fuel cell module 14 is provided with a manually operated shut-off valve 28 on the module side. Upstream of the shut-off valve 28, T-pieces 30 and 34 or a corner piece 32 are installed in the supply line 20. A first pressure vessel 22 is connected via the T-piece 30. It is understood that additional pressure vessels can also be connected via additional T-pieces. Another pressure vessel is connected to the corner piece 32. If only one pressure vessel 22 is provided, a T-piece 30 is not required. It is understood that a linear connection is also possible instead of a corner piece 32.

[0067] A filling connection 36 with a valve opening in the direction of the supply line is connected to the T-piece 34. The pressure vessels 22 can be filled and refilled via the filling connection 36 when the shut-off valve 28 is closed. Instead of filling the pressure vessels 22 via the filling connection 36, empty pressure vessels 22 can also be replaced with full pressure vessels. To do this, a quick-connector 38 is opened and the tensioning straps 26 are released. The quick-connector 38 can, for example, be designed similarly to commercially available quick-connectors for gardening hoses, where the opening in the pressure vessel 22 is closed by a valve as soon as the quick-connector 38 is released. It goes without saying that any other connection can also be used.

[0068] The use of replaceable pressure vessels 22 enables the use of a deposit system, so that not every gas station has to provide the required fuel at a pump. In an alternative embodiment, the tank 16 is permanently integrated into the fuel cell module 14 and enclosed together with it. Only one filling nozzle is then accessible from the outside. The fuel cell module 14 is then somewhat larger but easier to install. The retrofit module comprising the fuel cell 14, tank 16, and the additional components described below is identified in Figures 3 to 6 by a dashed line 104. All other components are typical components that are installed during the manufacture of conventional, electrically powered vehicles 10.

[0069] During operation, the fuel cell 14 generates electrical energy. This is illustrated at 100 in Figures 3 and 4. The fuel cell 14 also generates thermal energy. This is illustrated by an arrow 102. The electrical energy is fed into the existing low-voltage vehicle electrical system 108 via a DC / DC converter 106. 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 as needed over and above the thermal energy from the fuel cell. This is illustrated by an arrow 112. Both the thermal energy 102 from the fuel cell 14, i.e. its waste heat, and the thermal energy 112 generated by the PTC heater 110 are transferred to the existing heating and cooling circuit (HVAC) 120 of the vehicle 10 via a heat exchanger.

[0070] The vehicle 10 has a low-voltage electrical system 108, to which a plurality of low-voltage electrical loads 114 are connected. These loads include control units, lights, comfort devices, window, seat, and steering wheel heaters, entertainment devices, and smaller drives for moving mirrors and the like. Also connected are low-voltage loads 116, which are required for thermal management. These include, for example, pumps, fans, and heaters. Excess low-voltage energy can be stored in a low-voltage battery 118 and is available again for the low-voltage network when needed.

[0071] In addition to the low-voltage electrical system 108, the vehicle 10 also has a high-voltage electrical system 122. The voltage in the high-voltage electrical system 122 is many times higher than the voltage in the low-voltage electrical system 108. For example, the low-voltage electrical system can be operated at 12 volts. The voltage in the high-voltage electrical system is significantly higher than 200 volts, for example, 400 volts. The high-voltage electrical system is supplied by a rechargeable high-voltage battery 124 (also referred to as an accumulator). For example, the high-voltage battery 124 can be a lithium-ion battery. The high-voltage battery 124 covers the electrical energy requirements of the drive unit 126, i.e., 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 prior to retrofitting. Typically, the vehicles provide a DC / DC converter 130, via which electrical energy from the high-voltage battery 124 can be provided to the low-voltage electrical system 108.

[0072] The fuel cell 14 now represents a second energy source, with which low-voltage energy is fed into the low-voltage electrical system 108 at 132. The voltage from the fuel cell 14 is converted by the DC / DC converter 106 to a voltage level slightly higher than 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 long range.

[0073] The fuel cell 14 therefore generates thermal energy, which can be used to heat vehicle components, particularly the high-voltage battery 124. This improves the range. It also ensures that less energy is drawn from the high-voltage battery 124 for the low-voltage vehicle electrical system. This also improves the range.

[0074] The retrofit module 104 is provided with an additional controller 134. The controller 134 serves to control the fuel cell 14 and the low-voltage heater 110. These components 14 and 110 are switched on and off according to sensor signals. The sensor signals, in particular the ambient temperature, are read from the OBD connector 136. In the present exemplary embodiment, however, additional sensors 138 are also provided in the retrofit module 104. One of the sensors is a current sensor 146 for measuring current between the DC / DC converter 130 and the low-voltage vehicle electrical system 108, as well as a current sensor 147 between the DC / DC converter 106 and the low-voltage vehicle electrical system 108. When the vehicle 10 is switched on, the electrical consumers 114 are gradually switched on. The voltage measured by a sensor U normally drops.The vehicle's own control system therefore provides for the voltage in the low-voltage electrical system to be slightly increased before the low-voltage consumers 114 are switched on. A trigger is used for this, such as the approach of the vehicle key or the opening of a vehicle door. Depending on the current and / or voltage curve, the control system 134 interprets this as meaning that the vehicle 10 will soon require electrical and / or thermal energy and switches on the fuel cell 14.

[0075] The sensors 147 and 148 shown in Figures 3 and 4 are intended to determine the power fed into the low-voltage vehicle electrical system by the high-voltage battery. The controller switches on the fuel cell when the voltage measured at sensor 148 for the feed-in is above a threshold value, in particular more than 1 volt above a rest voltage. If necessary, the retrofit module 104 contains an additional low-voltage battery 150. This is illustrated in Figure 4.

[0076] The embodiment in Figure 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 electrical power required to maintain the vehicle's heat. In this configuration, the high-voltage heater can be switched off completely or operates at a reduced load.

[0077] Figure 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). The thermal energy of the fuel cell is added to lines 214 and 216 as well as to the evaporator 215. This enables the refrigerant enthalpy to be increased and the power utilization in the heat pump to be improved.

[0078] The exemplary embodiments explained above serve to illustrate the invention claimed in the claims. Features which are disclosed together with other features can generally also be used alone or in combination with other features which are explicitly or implicitly disclosed in the text or in the drawings in the exemplary embodiments. Dimensions and sizes are given only as examples. Suitable ranges will become apparent to those skilled in the art from their specialist knowledge and therefore need not be explained in more detail here. The disclosure of a specific embodiment of a feature does not mean that the invention is to be limited to this specific embodiment. Rather, such a feature can be implemented by a variety of other embodiments familiar to those skilled in the art.The invention can therefore be realized not only in the form of the embodiments explained, but by all embodiments covered by the scope of protection of the appended claims.

[0079] The terms "top," "bottom," "right," and "left" refer exclusively to the attached drawings. It is understood that claimed devices may also assume other orientations. The terms "containing" and "comprising" mean that additional, unmentioned components may be provided. The terms "essentially," "predominantly," and "predominantly" include all features that exhibit a property or content in the majority, i.e., more than all other mentioned components or properties of the feature—for example, more than 50% for two components.

Claims

Patent claims 1. Electrically powered vehicle (10) comprising (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 can be heated with thermal energy from the fuel cell (14); and (d) a low-voltage on-board network (108) for supplying further low-voltage electrical consumers (114); characterized in that (e) the low-voltage on-board network (108) can be supplied with low-voltage energy from the fuel cell (14).

2. Vehicle according to one of the preceding claims, characterized in that the low-voltage energy from the fuel cell (14) can be fed into the low-voltage vehicle electrical system (108) at a voltage which is higher than the voltage of the low-voltage vehicle electrical system.

3. Vehicle according to one of the preceding claims, characterized in that the low-voltage on-board network (108) has a voltage of 12 volts, 24 volts or 48 volts or another voltage up to 60 volts during operation.

4. Vehicle according to claim 2 or 3, characterized in that the low-voltage energy from the fuel cell (14) can be fed into the low-voltage vehicle electrical system with a voltage difference of 0.01 to 5 volts above the voltage of the low-voltage vehicle electrical system (108).

5. Vehicle according to one of the preceding claims, characterized in that an additional electrical low-voltage heater (110) for heating the High-voltage vehicle battery (124) and / or other vehicle equipment is provided, which can be at least partially supplied with electrical energy from the fuel cell (14).

6. 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), the passenger compartment and / or other vehicle devices, and the thermal energy of the fuel cell (14) and / or an additional electrical low-voltage heater (110) can be fed into the heating and cooling circuit (120).

7. Vehicle according to claim 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).

8. Vehicle according to claim 6 or 7, characterized in that the heating and cooling circuit (120) comprises a heat pump (200) with 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 the heating element (110) can be fed downstream to the expansion valve (213) or upstream to the compressor (211).

9. 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 / or the heating element (110) can be fed upstream to the high-voltage heater (128).

10. Vehicle according to one of the preceding claims 6 to 8, characterized in that thermal energy of the fuel cell (14) can be transferred to the heating and cooling circuit (120) via an air flow.

11. 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 a low-voltage heater (110) operated with electrical energy from the fuel cell can be transferred via the air flow to the evaporator, the high-voltage battery (124), the heating and cooling circuit (120) or to other components requiring heat.

12. Vehicle according to one of the preceding claims, characterized in that an additional control (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).

13. Vehicle according to claim 12, characterized in that the additional control (134) controls the low-voltage heater (110).

14. Vehicle according to claim 13, characterized in that sensors (138) are provided for determining the power fed from the high-voltage battery (124) into the low-voltage vehicle electrical system (108), and the control system switches on the fuel cell (14) when the voltage measured for the feed-in is above a threshold value, in particular more than 1 volt above a rest voltage.

15. Vehicle according to claim 14, characterized in that a vehicle diagnostic system (OBD) (136) is provided and the signals from the sensors can be transmitted at least partially to the additional control (134) via the vehicle diagnostic system (136).

16. Vehicle according to claim 14, characterized in that a DC / DC converter (106) is provided between the fuel cell (14) and the low-voltage vehicle electrical system (108), and / or a DC / DC converter (130) is provided between the high-voltage battery (124) and the low-voltage vehicle electrical 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 vehicle electrical system (108).

17. Vehicle according to claim 16, characterized in that the controller (134) is arranged such that the fuel cell (14) is started when a power determined from the signals of the current sensor (147) on the DC / DC converter between the high-voltage battery (124) and the low-voltage vehicle electrical system (108) exceeds a threshold value over a predetermined period of time.

18. Vehicle according to claim 16 or 17, characterized in that the control (134) is arranged such that the fuel cell (14) is switched off when a power determined from the signals of the current sensor (147) falls below a threshold value over a predetermined period of time.

19. Vehicle according to claim 18, characterized in that the controller (134) is configured such that the fuel cell (14) is no longer started for a predetermined period of time after a predetermined number of restarts.

20. 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 control determines a requirement for thermal energy from the ambient temperature.

21. A retrofit module for retrofitting an electrically powered vehicle with an electric drive (126) for propelling the vehicle (10), an electrically rechargeable high-voltage vehicle battery (124) for supplying the electric drive (126), and a low-voltage vehicle electrical system (108) for supplying additional low-voltage electrical consumers (114); wherein the retrofit module contains a fuel cell (14) which generates low-voltage electrical energy with which the low-voltage vehicle electrical system (108) can be supplied, and thermal energy with which the high-voltage vehicle battery (124) can be heated.

22. Retrofit module according to claim 21, characterized in that a low-voltage battery (118) is included, which can be integrated into the low-voltage vehicle electrical system (108).

23. A method for operating a vehicle (10) according to any one of claims 2 to 20, comprising the steps: (a) determining the state of charge of the high voltage battery (124); (b) generating low-voltage electrical energy with the fuel cell (14); (c) feeding the electrical energy into the low-voltage battery (118); and (d) feeding electrical energy from the low-voltage vehicle electrical system (108) into the high-voltage battery (124) via a charging network connection when the state of charge of the high-voltage battery falls below a threshold value.

24. Method according to claim 23, characterized in that the operation is carried out manually with intervention by the driver or automatically without intervention by the driver.

25. The method according to claim 23 or 24, characterized in that the fuel cell (14) is switched on when the temperature of the high-voltage battery (124) is below a threshold value.

26. A method for operating a vehicle (10) according to any one of claims 2 to 20, characterized in that: (a) the state of charge of the low-voltage battery (118) is monitored; (b) the fuel cell (14) is switched on when 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.

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