motor vehicle

Abstract

The invention relates to a motor vehicle (2) having an energy storage device (10) connected to a plug (14) via a charging unit (12). The charging unit (12) has a first precharging resistor (50) bridged by a first switching element (20), wherein the first precharging resistor (50) is assigned to an interior heater (56) as a heating element (60). The invention further relates to a method (64) for operating a motor vehicle and the use of a precharging resistor (50).

Description

[0001] The invention relates to a motor vehicle with an energy storage device connected to a plug via a charging unit. Furthermore, the invention relates to a method for operating a motor vehicle and the use of a pre-charging resistor of a charging unit.

[0002] Motor vehicles, such as passenger cars, have a main drive for propulsion, with the main drive increasingly comprising an electric motor. In this case, for example, only one or more electric motors are used to propel the motor vehicle, so that the motor vehicle is designed as an electric vehicle. In an alternative to this, the motor vehicle also comprises an internal combustion engine. A high-voltage on-board electrical system is usually used to supply power to the electric motor, which is fed by an energy storage device in the form of a high-voltage battery. The high-voltage battery has several battery modules, which are usually identical in design. Each of the battery modules, in turn, has several individual batteries, some of which are electrically connected in series and some in parallel.Thus, each of the battery modules provides an electrical direct voltage that is a single or multiple of one of the batteries.

[0003] To heat the interior of a motor vehicle, cooling water generated during operation of the combustion engine is typically used. This cooling water is fed to a heat exchanger coupled to a fan duct that reaches the interior. Without the combustion engine, such cooling is not possible. In this case, an interior heater is used, which has several heating elements, such as heating resistors. These are powered by the energy storage devices.

[0004] When charging the energy storage device, a charging unit in the motor vehicle is usually used. This converts an electrical voltage provided by a charging station into a voltage suitable for charging the energy storage device. For this purpose, the charging unit usually comprises a rectifier and / or a DC-DC converter. These usually have several semiconductor switch elements that are actuated to achieve the desired electrical voltage. To stabilize the electrical voltage thus provided and / or used, a capacitor is usually present that serves as an electrical intermediate (circuit) storage. If these capacitors are not charged, they essentially provide no electrical resistance at the start of the charging process, so that a comparatively large electrical current is passed through the charging unit, which could lead to damage.To prevent this, so-called pre-charging resistors are used to connect the capacitors to the charging station, for example, via the rectifier. These pre-charging resistors limit the electrical current carried by the charging unit. When the capacitor is sufficiently charged, the pre-charging resistors are bypassed with a low resistance, thus reducing electrical losses.

[0005] When the semiconductor switches of the rectifier / DC-DC converter are switched, electrical losses occur, which is why the rectifier or DC-DC converter must be cooled. The excess heat dissipated in this process is used to heat the interior, especially in relatively cool ambient temperatures. However, this is only possible during charging. The separate interior heater continues to be used while the vehicle is in operation.

[0006] From US 2023 / 0 226 933 A1, motor vehicles are known to which an energy storage device is connected via a charging unit with a plug, wherein the charging unit has a first pre-charging resistor which is bridged by a first switching element.

[0007] DE 10 2021 133 998 B3 discloses a precharging resistor also as a heating element for heating a coolant. The arrangement of the precharging resistor in the housing of a battery system also heats the interior of the battery housing.

[0008] The invention is based on the object of specifying a particularly suitable motor vehicle and a particularly suitable method for operating a motor vehicle as well as a particularly suitable use of a precharging resistor, wherein manufacturing costs and / or weight are advantageously reduced.

[0009] With regard to the motor vehicle, this object is achieved according to the invention by the features of claim 1, with regard to the method by the features of claim 9, and with regard to the use by the features of claim 10. Advantageous further developments and refinements are the subject of the respective subclaims.

[0010] The motor vehicle is preferably land-based and preferably has a number of wheels, of which at least one, preferably several or all, are expediently driven by a main drive. Preferably, the main drive is designed entirely electric, and the motor vehicle is, for example, an electric vehicle. In an alternative, the drive additionally has an internal combustion engine, so that the motor vehicle is designed as a hybrid motor vehicle. At least, however, the main drive comprises an electric motor, by means of which the power required for the propulsion of the motor vehicle is provided. Thus, the main drive is an electric motor main drive. Suitably, one, preferably several, of the wheels is designed to be steerable. This makes it possible to move the motor vehicle independently of a specific roadway, for example rails or the like.In this case, it is advantageously possible to position the motor vehicle essentially anywhere on a roadway, which is made, in particular, of asphalt, tar, or concrete. The motor vehicle is, for example, a commercial vehicle, such as a truck or a bus. However, the motor vehicle is particularly preferably a passenger car.

[0011] The motor vehicle, for example, has a high-voltage electrical system. The high-voltage electrical system supplies power to the main electric drive, which will also be referred to simply as the main drive in the following. For this purpose, the main drive and the high-voltage electrical system are electrically coupled. When the main drive is in operation, i.e., when the motor vehicle is to be accelerated or at least moved at a constant speed, electrical energy is drawn from the high-voltage electrical system by means of the main drive. The main drive preferably comprises a converter, by means of which the electrical voltage provided by the high-voltage electrical system is converted into a voltage that is applied to the electric motor, in particular any electromagnets of the electric motor. The converter is preferably designed as a pulse-controlled inverter.

[0012] The motor vehicle comprises an energy storage device, which is expediently configured as a battery or at least comprises several batteries. The energy storage device is preferably a high-voltage battery or comprises one. The energy storage device comprises, in particular, two terminals that serve to establish electrical contact with other components of the motor vehicle. The terminals are provided and configured for this purpose. In particular, a specific direct current voltage is present between the terminals during operation. In particular, the voltage present at the terminals is between 400 V and 800 V. Expediently, any high-voltage vehicle electrical system is supplied by the energy storage device.

[0013] The motor vehicle further comprises a charging unit which serves to charge the energy storage device, in particular from an external source. For this purpose, the motor vehicle has a plug which is designed in particular as a Type 1 or Type 2 plug and which is suitable, in particular intended and configured, to be electrically contacted with a charging infrastructure, such as a charging station or another part of a supply network. For this purpose, the plug has in particular corresponding contacts which can be electrically contacted with corresponding mating contacts of a mating plug of the charging infrastructure. When the energy storage device is charged, electrical energy is fed to the energy storage device via the plug and the charging unit. The charging unit thereby carries out a suitable conversion of the electrical voltage provided at the plug.At least an adjustment is made by means of the charging unit so that the charging process of the energy storage device is controlled or regulated by means of it.

[0014] The charging unit comprises a first pre-charging resistor which is bridged by a first switching element. The parallel circuit comprising the first pre-charging resistor and the first switching element is arranged in particular between the energy storage device and the plug. When the first switching element is open, the electrical current conducted between the energy storage device and the plug is conducted via the first pre-charging resistor. If, on the other hand, the first switching element is closed, i.e. is electrically conductive, the electrical current conducted between the plug and the energy storage device is conducted predominantly via the first switching element due to the reduced electrical resistance. This reduces electrical losses. The first switching element is designed, for example, as an electrical switching element, for example a semiconductor switch.Alternatively, the first switching element is or includes a mechanical switch, such as a relay or a contactor.

[0015] When the first switching element is open, i.e. electrically non-conductive, the electrical current conducted between the plug and the energy storage device via the charging unit is limited by means of the first pre-charging resistor, thus preventing damage to the charging unit or other components of the motor vehicle. In particular, the first pre-charging resistor / first switching element is located on the side of the charging unit facing the plug and forms, for example, the connection between the charging unit and the plug. If the charging unit has a capacity or, for example, the energy storage device is relatively empty, a comparatively low electrical resistance is initially provided during a charging process, so that a comparatively large electrical current is conducted between the energy storage device and the plug when the first switching element is closed.In this case, the first switching element is open. Conveniently, the first switching element is always open at the start of a charging process, so that the electrical current is initially limited by the first pre-charging resistor. Only when the electrical current flowing through the plug / charging unit is below a certain limit is the first switching element closed.

[0016] The motor vehicle further comprises an interior space, which in particular serves to accommodate persons. A driver's seat is expediently arranged in the interior space, and / or controls for controlling the motor vehicle, such as a steering wheel, are located therein. Alternatively, or in combination with this, seats for persons transported by the motor vehicle are arranged in the interior space, for example. The motor vehicle comprises an interior heater, which is suitable, in particular provided and configured, for heating the interior space, which is also referred to, for example, as the passenger compartment. For this purpose, the interior heater comprises a heating element, which is in particular electrically configured. The heating element is, for example, a heating coil or an ohmic resistor, such as a ceramic resistor. For example, the interior heater comprises a fan, by means of which an airflow can be created over the heating element.The air flow heated in this way is directed into the interior. Alternatively, the heating element is arranged directly within the interior, for example, in an armrest or a seat, so that the heating element at least partially forms a seat heater.

[0017] The heating element of the interior heater is formed by the first pre-charging resistor. In other words, the first pre-charging resistor is assigned to the interior heater as a heating element. Thus, the first pre-charging resistor performs two functions: limiting the electrical current conducted via the plug, and generating heat, which warms the interior of the vehicle. In particular, the interior heater, with the exception of the pre-charging resistor, has no additional heating element. As a result, the number of required components is reduced, thus reducing material and manufacturing costs. The weight of the vehicle and the required installation space are also reduced.In addition, the first pre-charging resistor, which is only used for a comparatively short period of time when limiting the electrical current, is used more frequently due to its additional use in the interior heater, thus improving utilization. In summary, according to the invention in particular, the interior heater and the charging unit are not separate from each other, but rather share (at least) the first pre-charging resistor. For example, with the exception of the first pre-charging resistor, the charging unit has no further pre-charging resistors, and the interior heater has no further heating elements. This makes it possible to design the motor vehicle comparatively compact.

[0018] The charging unit preferably also comprises liquid cooling. The liquid cooling has a plurality of channels through which a liquid, in particular water, is conducted. By means of the liquid cooling, any waste heat generated during operation of the charging unit is dissipated, for example into the environment. Alternatively, this heat is fed to the interior heater, which comprises a heat exchanger for this purpose. This results in (additional) heating of the interior using waste heat from the charging unit, although this expediently occurs independently of the setting of the first switching element. However, an (additional) heat source is only present in the interior heater when the first switching element is open due to the first pre-charging resistor acting as a heating element. In this case, this heat is not waste heat but dedicatedly provided heat.

[0019] The charging unit expediently has one or more contactors, which are preferably arranged upstream between the plug and the first pre-charging resistor. This enables, in particular, galvanic isolation between the rest of the charging unit / energy storage device and the plug, thus increasing safety. The charging unit preferably comprises a rectifier, which is designed, in particular, in the manner of a bridge rectifier. The first pre-charging resistor and the first switching element are expediently located electrically between the rectifier and the plug. This ensures that no comparatively high electrical current is conducted via the rectifier, which is why the requirements for the components of the rectifier are reduced, and therefore manufacturing costs are reduced. In other words, the required short-circuit strength of the rectifier is reduced, in particular.A choke is expediently present. This is used, in particular, to smooth the electrical current. The choke is suitably located between the first pre-charging resistor / the first switching element and the rectifier, so that it is also protected by the first pre-charging resistor. Thanks to the rectifier, it is thus possible to apply an alternating electrical voltage to the plug, which is converted by the charging unit into a direct electrical voltage required to charge the energy storage device. For example, the first pre-charging resistor / the first plug is located between the rectifier and the energy storage device. This also makes it possible to operate the first pre-charging resistor without using the rectifier, for example even when no alternating electrical voltage is applied to the plug.

[0020] A capacitor is expediently assigned to the rectifier, particularly on the side facing the energy storage device. This capacitor stabilizes the electrical voltage provided by the rectifier, thereby reducing the load on the energy storage device and other components connected to the rectifier. Due to the first precharging resistor, when the capacitor is not charged, the electrical current conducted through the rectifier is limited when the first switching element is open.

[0021] For example, the rectifier is a passive rectifier and is formed, for example, only by means of diodes. However, the rectifier is particularly preferably designed with feedback capability, so that it can also function as an inverter. Due to the feedback capability, it is possible, for example, to use the energy storage device as a temporary energy storage device to supply, for example, an island grid or the like. In this way, it is also possible to energize the first pre-charging resistor when no electrical current is being conducted via the plug, i.e. while the motor vehicle is in operation. In other words, the first pre-charging resistor is energized when the energy storage device is not being charged, and the charging unit is designed in particular in this way.The charging unit expediently comprises a switch unit so that the first pre-charging resistor can be electrically contacted on both sides with different components of the rectifier, in particular different bridge branches. Consequently, with a suitable setting of the switch unit and / or the rectifier, which functions in particular in the manner of an inverter, an electrical current can be supplied to the first pre-charging resistor by means of the energy storage device, wherein no electrical current is conducted via the plug. For this purpose, the switch unit is expediently arranged between the first pre-charging resistor and the plug, and the switch unit preferably has a plurality of switches. It is preferably possible to connect the first pre-charging resistor between individual phases / connections / poles of the rectifier by means of the switch unit.

[0022] For example, the level of the electrical voltage used to charge the energy storage device is predetermined by the electrical voltage applied to the plug or by the operation of the rectifier. For this purpose, a phase-cutting or phase-cutting control is used, for example. However, the charging unit particularly preferably comprises a DC-DC converter that is electrically arranged between the rectifier and the energy storage device. Due to the DC-DC converter, it is possible to adapt the electrical DC voltage provided by the rectifier, so that, for example, the charging process of the energy storage device is improved and electrical losses are reduced. The requirements for the individual components of the rectifier are also reduced, which lowers manufacturing costs.If the rectifier is designed to be capable of regenerating energy, the DC-DC converter is preferably also capable of regenerating energy, so that the rectifier can be fed from the energy storage device via the DC-DC converter.

[0023] For example, the DC-DC converter is a boost converter, a buck converter, or comprises both. For example, the DC-DC converter has a boost converter and a buck converter, or this has, for example, a bridge circuit with different switches. The DC-DC converter is expediently designed as a cascaded / stepped buck-boost converter. In particular, the DC-DC converter is designed as a push-pull converter, a forward converter, or a forward converter. In particular, any required diodes are replaced by switches so that the DC-DC converter is capable of regenerative power. Preferably, the DC-DC converter and the rectifier are designed as a common structural unit, in particular as a power controller. Any available capacitance is suitably assigned to both.This makes it possible to provide a comparatively compact charging unit, with electrical losses reduced due to the short electrical connections. It is also possible, in particular, to use any capacitance that functions as an intermediate circuit capacitor or the like between both, thus reducing the number of required components.

[0024] For example, the charging unit is formed solely by the first pre-charging resistor, the first switching element, the rectifier, and optionally the DC-DC converter. Particularly preferably, however, the charging unit comprises an EMC filter circuit. This is arranged, for example, between the first switching element and the plug. The EMC filter circuit increases electromagnetic compatibility, so that voltage / current peaks or other artifacts caused by charging the energy storage device using the charging unit do not repercussions in any supply network connected to the plug. In particular, the EMC filter circuit comprises a filter, such as a high-pass filter, a low-pass filter, or preferably a band-pass filter. Alternatively, the EMC filter circuit is arranged between the energy storage device and the rectifier.If a DC-DC converter is present, the EMC filter voltage is expediently arranged between the DC-DC converter and the energy storage device. The EMC filter circuit is designed, for example, as a high-pass filter, low-pass filter, or band-pass filter. As a result, peaks / artifacts in the electrical voltage resulting, for example, from the operation of the rectifier are not conducted to the energy storage device, thus reducing stress. The EMC filter circuit preferably forms the connection to the charging unit. Suitably, two EMC filter circuits are present, representing the different connections of the charging unit. All other (electrical / electronic) components of the charging unit are located between the EMC filter circuits.Due to this arrangement of the EMC filter circuits, the energy storage device and any power grid connected to the plug are subjected to comparatively low loads when the charging unit is in operation, thus reducing the demands on the operation of the charging unit, such as the rectifier, and the other components used. If a contactor is present, it is suitably arranged between the EMC filter circuit and the first pre-charging resistor.

[0025] For example, the rectifier is designed as a single-phase device. In this case, the plug is also designed as a single-phase device, and the first switching element and the first pre-charging resistor are assigned to this phase. Alternatively, the plug is designed as a multi-phase device, so that it can be used with multiple mating plugs. Preferably, the rectifier is also designed as a multi-phase device, so that the amount of energy that can be supplied by the rectifier is increased, thus accelerating charging of the energy storage device. In particular, the plug and the rectifier are designed as three-phase devices.

[0026] For example, the first switching element and the first precharging resistor are assigned to one of the phases. For example, the first precharging resistor is the only precharging resistor. However, the remaining phases are preferably also each assigned an additional precharging resistor bridged by a respective additional switching element. This prevents the formation of excessive electrical current there as well. In particular, the additional switching elements and the respective additional first precharging resistors are arranged between the plug and in the rectifier. The switch unit, if any, is expediently present and is located in particular between the individual switching elements and the plug.In this case, the switch unit is designed in particular such that the sides of the switching elements / pre-charging resistors facing away from the rectifier can be connected to a common point which is, for example, detached from the plug or electrically contacted with it. Thus, it is possible to use the switch unit to connect each phase of the plug to all phases of the rectifier, which occurs in particular when a single-phase alternating voltage is applied to the plug. In this way, it is also possible, particularly if the rectifier is capable of feedback, to create an electrical current flow via the first pre-charging resistor, regardless of whether an electrical voltage is applied to the plug. The energy storage device is used in particular to supply current to the first pre-charging resistor.

[0027] Conveniently, all switching elements, i.e., the additional switching elements and the first switching element, are identical in design, allowing the use of identical parts. For example, the additional precharging resistors are identical in design to the first precharging resistor. Conveniently, the additional precharging resistors are then also used as heating elements. Alternatively, only the first precharging resistor is used as a heating element, and the additional precharging resistors are independent of the interior heater. Thus, they are used relatively rarely, allowing for the use of more cost-effective components.

[0028] For example, all precharging resistors are assigned to the interior heater. Alternatively, only some of the precharging resistors are assigned to the interior, and suitably only the first precharging resistor. If multiple precharging resistors are assigned to the interior heater, they are used simultaneously when the interior heater is operating, for example. Alternatively, they are used alternately, thus reducing the load.

[0029] The motor vehicle preferably comprises a housing in which the further switching elements, the further pre-charging resistors, and the first switching element are arranged. Any rectifier and / or any DC-DC converter is expediently arranged within the housing. Any liquid cooling system is expediently arranged within the housing. For example, the first pre-charging resistor is also arranged in the housing, and preferably also all remaining components of the interior heater. This simplifies assembly. However, it is particularly preferred that the first pre-charging resistor be arranged outside the housing. In particular, all components of the charging unit, with the exception of the first pre-charging resistor, are arranged within the housing. This means that the housing is designed in the manner of a module, which facilitates assembly.These components can be arranged in an optimized manner due to the first pre-charging resistor located outside them, and the structure of the interior heater can also be optimized independently.

[0030] For example, the first pre-charging resistor is attached, and expediently the other components of the interior heater are also attached. The interior heater and the charging unit are thus present as a common structural unit, which simplifies assembly. However, it is particularly preferred for two connections to be incorporated into the housing, to which a cable, which in particular has two wires, is connected. The first pre-charging resistor is connected to the connections, and in particular to the first switching element, via the cable. In particular, the first switching element is guided against the two connections, for example by means of a further cable or busbars. For example, the connections are provided by means of the further cable, which merges into the cable. Alternatively, the connections are designed in the manner of plug-in connections, thus simplifying storage of the housing.The use of the cable makes it possible to mount the interior heater relatively far away from the housing, allowing for flexible installation. The connectors allow for separate storage of the cable and the interior heater, further simplifying storage and installation.

[0031] The method is used to operate a motor vehicle with an energy storage device connected to a plug via a charging unit. The charging unit has a first pre-charging resistor, which is bridged by a first switching element. The first pre-charging resistor is assigned to an interior heater as a heating element. The motor vehicle is, for example, a passenger car (car), a truck (lorry), or a bus.

[0032] In the method, the first switching element is opened depending on a heating request. In other words, the heating request is first detected and then the first switching element is opened or at least left in the open state, even if it should be closed based on other operating data or the like of the charging unit. If the energy storage device is to be charged, the method expediently first opens the first switching element and then an electrical current is passed through the charging unit, for example via the rectifier, if present. Because the first switching element is open, the electrical current passed is limited. In particular, the first switching element is left open until any capacity or other intermediate storage device in the charging unit is at least sufficiently charged or a specific period of time has elapsed, for example 5 seconds, 2 seconds or 1 second.Subsequently, when there is no heating requirement, the first switching element is opened so that electrical losses are reduced.

[0033] The motor vehicle preferably comprises a control unit that is suitable, expediently provided and configured, to carry out the method. The control unit is implemented, for example, by means of a single device or divided between different devices. The invention likewise relates to such a control unit. For example, the control unit is a component of the charging unit and / or the interior heater. The control unit is designed, for example, as an application-specific integrated circuit (ASIC) or comprises a programmable computer, such as a microprocessor. In particular, the control unit comprises a memory on which a computer program product is stored which, when the program is executed by a computer, in particular the microprocessor, causes the computer to carry out the method. The computer is expediently a component of a control unit or electronics and is formed, for example, by means of the latter.The computer preferably comprises or is formed by a microprocessor. The computer program product is, for example, a file or a data carrier containing an executable program that, when installed on a computer, automatically executes the method.

[0034] The invention further relates to such a control device and also to such a computer program product. Furthermore, the invention relates to a storage medium on which the computer program product is stored. Such a storage medium is, for example, a CD-ROM, a DVD, or a Blu-ray disc. Alternatively, the storage medium is an SD card, a USB stick, or another storage device that is, for example, rewritable or only writable once. Such a storage device is, for example, a flash memory, a RAM, or a ROM.

[0035] The heating request is created, for example, by a user who, in particular, makes a manual or other input, or by an on-board computer. Once this request has been made, it is detected, and as a result, the first switching element is opened. Consequently, the electrical current supplied to the energy storage device is passed through the first pre-charging resistor, so that it is heated. Expediently, the fan of the interior heater, if present, is activated here, so that overheating of the first pre-charging resistor is avoided and the heat is transported into the interior of the motor vehicle. As soon as the heating request is no longer present, the first switching element is closed again. Consequently, no electrical current is passed through the first pre-charging resistor, so that it is no longer heated.

[0036] If heating is required after charging or during any other operation of the motor vehicle, i.e. in particular while moving or at least when the plug is not connected to a charging infrastructure, energy is taken from the energy storage device and fed to the first pre-charging resistor. In other words, the first pre-charging resistor is energized by means of the energy storage device. In this case, the first switching element is also open, so that no electrical current can flow through it. The switch unit and the rectifier are expediently present. In particular, a suitable voltage is provided by means of the rectifier, which voltage is applied to both sides of the first pre-charging resistor at least also by means of the switch unit. For example, a direct current or an alternating voltage is applied to the first pre-charging resistor for this purpose.If a DC-DC converter is present, for example, the electrical voltage is adjusted to prevent overloading of the first pre-charging resistor / rectifier. If additional switching elements / pre-charging resistors are present that are not assigned to the interior heater, the other switching elements are left closed or closed even when heating is required. This reduces electrical losses.

[0037] A pre-charging resistor of a charging unit is used as a heating element for heating an interior space. The charging unit is suitable, in particular provided and configured, for charging an energy storage device. The charging unit preferably comprises a capacitor, and the pre-charging resistor serves to limit an electrical current carried by the charging unit when the capacitor is discharged. Since the pre-charging resistor is also used as a heating element, it has two functionalities. In particular, the heating element is a component of an interior heater. For example, the interior space is a living space or business space, and the energy storage device is, for example, stationary. Alternatively, the interior space is formed by a mobile dwelling, for example a caravan or a tent. Particularly preferably, the interior space is a component of a motor vehicle and suitably a passenger compartment.

[0038] The further developments and advantages explained in connection with the motor vehicle are to be transferred analogously to the method / the control unit / the computer program product / the storage medium / the use as well as to each other and vice versa.

[0039] An embodiment of the invention is explained in more detail below with reference to a drawing. In the drawings: Fig. 1 schematically simplified a motor vehicle with a charging unit and an interior heater Fig. 2 schematically shows the loading unit in a higher level of detail, and Fig. 3 a method for operating the motor vehicle.

[0040] Corresponding parts are provided with the same reference numerals in all figures.

[0041] In Fig. 1 shows a simplified schematic representation of a motor vehicle 2 in the form of a passenger car (car). The motor vehicle 2 has a plurality of wheels 4, by means of which contact is made with a road surface (not shown in detail). At least some of the wheels 4 are driven by a main drive 6 which comprises an electric motor. The main drive 6 is therefore an electric motor main drive. In addition, the main drive 6 has a converter, namely a pulse-controlled inverter, by means of which the electrical voltage required to power the electric motor is provided. The converter itself is powered, i.e. operated, by means of a high-voltage on-board electrical system 8, by means of which an electrical direct voltage of 800 V is provided during normal operation.

[0042] The high-voltage on-board electrical system 8 is powered by an energy storage device 10, which is designed as a high-voltage battery. The energy storage device 10 is connected via a charging unit 12 to a plug 14 having a plurality of contacts 16. Each of the contacts 16 can be connected to a corresponding mating contact of a mating connector (not shown) of a charging infrastructure, so that energy can be transferred from the charging infrastructure to the energy storage device 10. The plug 14 is thus designed to be multi-phase and can be connected to a three-phase alternating current network. Each of the phases of the electrical alternating current network is assigned one of the contacts 16. In addition, one of the contacts 16 is electrically assigned to ground, and another to the neutral conductor. In summary, the energy storage device 10 is connected to the plug 14 via the charging unit 12.

[0043] The charging unit 12 has two EMC filter circuits 18, each of which includes a bandpass filter (not shown in detail). Electrically, the two EMC filter circuits 18 form the ends of the charging unit 12 facing the plug 14 and the charging unit 10, respectively. The individual phases of the plug 14, i.e., the associated contacts 16, are routed to the associated EMC filter circuit 18. One of these phases is routed via a first switching element 20, and the remaining two are routed via a further switching element 22, each of which is identical in construction, to a rectifier 24, which is thus also multi-phase, namely three-phase. A DC-DC converter 26 is electrically connected downstream of the rectifier 24 and is electrically connected to the remaining EMC filter circuit 18, which is also formed by a bandpass filter.

[0044] This EMC filter circuit 18, the DC-DC converter 26 and the rectifier 24, which is designed as a B6 rectifier, are, as shown in Fig. 2, integrated into a charging controller 28, which also has several capacitors 30, by means of which the provided electrical voltage is stabilized. The charging controller 28, and thus also the DC-DC converter 26 and the rectifier 24, are designed to be capable of regenerating energy.

[0045] Thus, the charging unit 12 comprises the DC-DC converter 26, which is electrically arranged between the rectifier 24 and the energy storage device 10.

[0046] Each of the phases of the three-phase rectifier 24 is connected to the associated switching element 20, 22 via a choke 32. In summary, the first switching element 20 is assigned to one of the phases, and each of the remaining phases is assigned one of the further switching elements 22. On the side opposite the chokes 32, the switching elements 20, 22 are connected to a switch unit 34 having two switches 36. By means of the switches 36, the phases on the side facing away from the rectifier 24 can be electrically short-circuited to one another, i.e., electrically connected to a common point. If the phases are not short-circuited, they are each connected by means of the switch unit 34 via a contactor 38 to the EMC filter circuit 18 of the charging unit 12 assigned to the plug 14. A corresponding contactor is also assigned to the neutral conductor.

[0047] The additional switching elements 22 are each bridged by means of an additional pre-charging resistor 40, which, like the additional switching elements 22, the first switching element 40, the switch unit 34, the two EMC filter circuits in 18, the contactors 38, the charging controller 28, and the chokes 32, are arranged in a common housing 42. A liquid cooling system 44 is also incorporated into the housing 42 and is connected to a cooling circuit (not shown in detail). The liquid cooling system 44 dissipates any heat loss generated in the housing 42, for example, into the environment of the motor vehicle 2, or is used, for example, to control the temperature of the energy storage device 10.

[0048] Two terminals 46 are incorporated into the housing 42, which are connected to the phase assigned to the first switching element 20 by means of a busbar or the like. The first switching element 20 is connected between the two terminals 46. A cable 48 having two wires is connected to the terminals 46. A first pre-charging resistor 50, which is arranged outside the housing 42, is connected between the remaining ends. The charging unit 12 thus has the first pre-charging resistor 50, which is bridged by the first switching element 20. The first pre-charging resistor 50 is electrically arranged between the rectifier 24 and the plug 14.

[0049] In summary, the plug 14 and the regenerative rectifier 24 are designed as multi-phases, with the first pre-charging resistor 50 being assigned to one of the phases, by means of which the first switching element 20 is bridged. The remaining phases, however, are each assigned one of the further switching elements 22, which are bridged by the respectively assigned further pre-charging resistor 40. Essentially, only the first pre-charging resistor 50 of the charging unit 12 is arranged outside the housing 42. At least the further switching elements 22, the further pre-charging resistors 14, and the first switching element 20 are arranged in the housing 42. Consequently, the two EMC filter circuits 18 are also located within the housing 42, with one of them being electrically connected between the plug 14 and the first switching element 20 / the further switching elements 22, and the other between the energy storage device 10 and the rectifier 24.The two terminals 46 are introduced into the housing 42, to which the first pre-charging resistor 50 is connected via the cable 48.

[0050] The motor vehicle 2 further comprises an interior 52, in which, for example, a driver's seat 54 is arranged. To heat the interior 52, the motor vehicle 2 has an interior heater 56, which is arranged within a fan duct 58 that extends into the interior 52. The interior heater 56 has a heating element 60 and a fan 62. During operation, the fan 62 generates an air flow through the fan duct 58, which is guided along the heating element 60 and is thus heated. The air heated in this way is guided into the interior 52 by means of the fan duct 58. The first pre-charging resistor 50 of the charging unit 12 is used as the heating element 60. In other words, the first pre-charging resistor 50 is assigned to the interior heater 56 as the heating element 60. Due to the cable 48, a comparatively flexible arrangement of the housing 42 to the fan line 58 and the other components of the interior heater 56 is possible.Since the first precharging resistor 50 has two functionalities, the number of required components and thus also the weight of the motor vehicle 2 and the required installation space are reduced.

[0051] In Fig. 3 illustrates a method 64 for operating the motor vehicle 2, which is carried out at least partially by means of a control unit 65a. Thus, the motor vehicle 2 is operated according to the method 64, and the control unit 65a is suitable, provided, and configured to carry out the method 64. For this purpose, the control unit 65a comprises a computer 65b in the form of a microprocessor and a memory 65c. A computer program product 65d is stored in the memory 65c. The computer program product 65d comprises a plurality of instructions which, when executed by the computer 65b, cause it to carry out the method 64.

[0052] The method 64 begins in a first work step 66. If the motor vehicle 2, namely the energy storage device 10, is to be charged using the charging infrastructure, a second work step 68 is carried out. In this step, the first switching element 20 and the further switching elements 22 are initially opened. The switch unit 34 is also set such that the phases are separated from one another. The contactors 38 are then closed. As a result, a current flows from the charging infrastructure via the plug 14, the pre-charging resistors 40, 50 and the choke 32 to the rectifier 24. The semiconductor switches of the rectifier 24 are operated such that they provide an electrical direct voltage on the side facing the DC-DC converter 26, by means of which the capacitors 30 are charged.

[0053] When the capacitors 30 are sufficiently charged, a third work step 70 is carried out. In this step, the first switching element 20 and the other switching elements 22 are closed. The rectifier 24 is thus connected to the plug 14 with low resistance, so that electrical losses are reduced. The voltage converter 26 is then also operated so that the DC voltage provided by the rectifier 24 is increased or decreased to an electrical voltage suitable for charging the energy storage device 10. For this purpose, the semiconductor switches of the rectifier 24 and the voltage converter 26 are actuated as appropriate. The resulting electrical losses lead to heating. Part of the heat generated in this way is dissipated by the liquid cooling system 44. As soon as the energy storage device 10 is sufficiently charged, in a fourth work step 72 the operation of the charging controller 28 is stopped and the contactors 38 are opened.Thus, the charging unit 28 is galvanically separated from the connector 14, so that the mating connector of the charging infrastructure can be safely removed. The process 64 is then completed in a fifth step 74.

[0054] If a heating request 76 is detected during the charging process, a sixth work step 78 is carried out after the third work step 70. The heating request 76 is created, for example, by a user by actuating a corresponding input device, so that it is detected. In the sixth work step 78, the first switching element 20 is opened, and the electrical current assigned to this phase is therefore no longer conducted via the first switching element 20, but via the first pre-charging resistor 50. As a result, the latter heats up. In addition, the fan 62 is operated so that the air heated by the first pre-charging resistor 50 is conveyed into the interior 52 via the fan line 58. The other switching elements 22 remain closed during this time, so that excessive heating of the other pre-charging resistors 40 and thus of the housing 42 is prevented.When the request 76 is no longer present, the first switching element 20 is closed again and the operation of the fan 62 is stopped.

[0055] If the motor vehicle 2 is moving and therefore no charging process is taking place when the heating request 76 is detected, a seventh work step 80 is carried out after the first work step 66. In this seventh work step 80, the switch unit 34 is actuated such that all phases on the side of the first switching element 20 and the further switching elements 22 facing the plug 14 are electrically short-circuited. The further switching elements 22 are also closed and the first switching element 20 is opened. In a subsequent eighth work step 82, the charging controller 28 is operated such that electrical energy is drawn from the energy storage device 10 by means of it. Due to the setting of the switch unit 34, the resulting electrical current is not passed through the further pre-charging resistors 40, but through the first pre-charging resistor 50, so that the latter is heated.The fan 62 is also operated, which is why the heated air is introduced into the interior 52. As soon as the heating request 76 no longer exists, the operation of the charging controller 28 is discontinued, thus ending the current supply to the first pre-charging resistor 50. In addition, the fan 62 is shut down. Here, too, the method 64 is terminated in the subsequent fifth work step 74.

[0056] In summary, in method 64, the first switching element 20 is opened depending on the heating request 76, i.e., whenever the heating request 76 exists. As long as the heating request 76 exists, the first switching element 20 remains open. Thus, the first precharging resistor 50 is heated, and by means of this, the interior space 52 is heated. In other words, the first precharging resistor 50 is thus used as the heating element 60.

[0057] The invention is not limited to the exemplary embodiment described above. Rather, other variants of the invention can also be derived therefrom by those skilled in the art without departing from the scope of the invention. In particular, all individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the scope of the invention. List of reference symbols 2 motor vehicles 4 wheel 6 Main drive 8 High-voltage electrical system 10 energy storage 12 loading units 14 plugs 16 Contact 18 EMC filter circuit 20 first switching element 22 additional switching element 24 rectifiers 26 DC-DC converters 28 charging stations 30 capacity 32 Throttle 34 Switch unit 36 switches 38 contactor 40 additional precharge resistor 42 housings 44 Liquid cooling 46 connection 48 cables 50 first precharge resistor 52 Interior 54 Driver's seat 56 interior heaters 58 Blower line 60 heating element 62 blowers 64 procedures 65a control unit 65b Computer 65c storage 65d Computer program product 66 first step 68 second step 70 third step 72 fourth step 74 fifth step 76 Heating request 78 sixth step 80 seventh step 82 eighth work step

Claims

[1] Motor vehicle (2) with an energy store (10) which is connected to a plug (14) via a charging unit (12), wherein the charging unit (12) has a first pre-charging resistor (50) which is bridged by a first switching element (20), and wherein the first pre-charging resistor (50) is assigned to an interior heater (56) as a heating element (60), wherein the interior (52) is designed as a passenger compartment or passenger cell or as a mobile housing. [2] Motor vehicle (2) according to claim 1, characterized by that the charging unit (12) has a rectifier (24), wherein the first pre-charging resistor (50) is electrically arranged between the rectifier (24) and the plug (14). [3] Motor vehicle (2) according to claim 2, characterized by that the rectifier (24) is designed to be capable of regenerating energy. [4] Motor vehicle (2) according to claim 2 or 3, characterized bythat the charging unit (12) comprises a DC-DC converter (26) which is electrically arranged between the rectifier (24) and the energy store (10). [5] Motor vehicle (2) according to one of claims 2 to 4, characterized by that an EMC filter circuit (18) is arranged electrically between the first switching element (20) and the plug (14) and / or between the energy store (10) and the rectifier (24). [6] Motor vehicle (2) according to one of claims 2 to 5, characterized by that the plug (14) and the rectifier (24) are designed to be multi-phase, wherein the first switching element (20) and the first pre-charging resistor (50) are assigned to one of the phases and a further pre-charging resistor (40) bridged by a respective further switching element (22) is assigned to the remaining phases. [7] Motor vehicle (2) according to claim 6, characterized bythat the further switching elements (22), the further pre-charging resistors (40) and the first switching element (20) are arranged in a common housing (42) and the first pre-charging resistor (50) is arranged outside the housing (42). [8] Motor vehicle (2) according to claim 7, characterized by that two terminals (46) are introduced into the housing (42), to which the first pre-charging resistor (50) is connected via a cable (48). [9] Method (64) for operating a motor vehicle (2) according to one of claims 1 to 8, in which the first switching element (20) is opened as a function of a heating request (76). [10] Use of a pre-charging resistor (50) of a charging unit (12) for an energy storage device according to one of claims 1 to 8 as a heating element (60) for heating an interior space (52).

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