System for charging a rechargeable battery of an electric vehicle

Abstract

System for charging a rechargeable battery (1) of an electric vehicle, wherein the electric vehicle is equipped with an electric drive motor (2), a generator (4) generating a first alternating current output (3), an internal combustion engine (5) driving the generator and startable during the operation of the electric vehicle, and a first electrical charging plug device (6), characterized in that - that when the combustion engine is started, the generator can be used at least temporarily as an electrical power source to supply the battery with charging power, - that the first charging plug device is geometrically designed in such a way that a single-phase AC network (8) supplying a second output alternating current (7) can be connected to the first charging plug device with a first charging cable (9) in order to supply the battery with charging power as an electrical power source when the electric vehicle is switched off, - that the first charging connector is designed for a load with a maximum electrical voltage of at least 240 volts and a maximum current of at least 32 amperes and - that a second electrical charging plug (10) is integrated into the electric vehicle, to which a DC charging station (13) supplying a first DC current (12) can be connected with a second charging cable (11) when the electric vehicle is parked, so that when the electric vehicle is parked the DC charging station can be used either exclusively or simultaneously with the single-phase AC network as an electrical power source to supply the battery with charging power.

Description

[0001] The invention relates to a system for charging a rechargeable battery of an electric vehicle, in which the electric vehicle is equipped with an electric drive motor, a generator generating a first output alternating current, an internal combustion engine driving the generator which can be started during the driving operation of the electric vehicle and a first electrical charging plug device.

[0002] In individual local public transport, climate-friendly and environmentally friendly vehicle concepts with alternative drive systems, especially electric drives, are gaining increasing market share. These electric drives typically draw the electrical power for traction from high-voltage batteries, preferably rechargeable lithium-ion batteries. These secondary batteries offer several advantages in terms of energy and power density compared to other electrochemical energy storage technologies. In electric vehicles, these batteries are usually charged when the vehicle is stationary or parked, i.e., not ready to drive, via the AC power grid, usually the vehicle user's home electrical system, or via DC charging stations.In electric vehicles with a combustion engine that can be engaged while driving, charging is also possible while the vehicle is in operation or ready to drive. The combustion engine drives a generator to produce electricity, which can also be used to charge the battery. Preferably, the power output of the combustion engine serves to extend the range of an electric drive motor of the electric vehicle, which is why the combination of combustion engine and generator is referred to as a range extender in this document. Consequently, the electrical system architecture of an electric vehicle is subject to specific technical requirements, primarily concerning the energy and power flows when the vehicle is stationary and in motion. The system for charging the rechargeable battery is part of this electrical system architecture.

[0003] Charging systems for recharging the battery of an electric vehicle are known from the prior art. For example, document EP 0 596 988 A1 describes the electrical supply system of a battery-powered electric vehicle. This is based on a supply from public AC grids. Furthermore, document EP 0 610 258 B1 presents a charging station for electric vehicles, specifying in particular the requirement that the charging station provides a DC voltage.

[0004] It is an object of the present invention to provide an improved charging system for recharging a battery in an electric vehicle.

[0005] This problem is solved by a system for charging a rechargeable battery of an electric vehicle according to claim 1. Advantageous embodiments and further developments of the invention are set out in the dependent claims.

[0006] According to the invention, when the combustion engine is started, the generator can be used at least temporarily as an electrical power source to supply the battery with charging power, and the first charging plug device is geometrically designed such that a single-phase AC network supplying a second output AC current can be connected to the first charging plug device with a first charging cable in order to supply the battery with charging power as an electrical power source when the electric vehicle is switched off.The first charging connector is designed for a load with a maximum electrical voltage of at least 240 volts and a maximum current of at least 32 amperes, and a second electrical charging connector is integrated into the electric vehicle, to which a first DC charging station supplying DC current can be connected with a second charging cable when the electric vehicle is parked, so that when the electric vehicle is parked the DC charging station can be used either exclusively or simultaneously with the single-phase AC network as an electrical power source to supply the battery with charging power.

[0007] One advantage of the invention lies in the high degree of flexibility it offers the vehicle user regarding charging options for the rechargeable battery when the electric vehicle is parked. In addition to charging the battery at, for example, a public charging station via the DC charging connector (i.e., the second charging connector), charging at AC sources is also possible via the AC connector (i.e., the first charging connector).

[0008] According to a preferred embodiment of the present invention, the first AC output current is rectified to a second DC current by a first AC-DC converter and a second AC-DC converter connected in parallel to the first AC-DC converter. The parallel connection of the two converters results in, in particular, a high degree of country-specific flexibility in the design of the charging function at AC voltage sources.

[0009] According to a further preferred embodiment of the invention, the second direct current either supplies the electric drive machine with electrical power via a direct current-to-alternating current converter connected upstream of the electric drive machine, or the second direct current supplies the electric drive machine with electrical power via the direct current-to-alternating current converter connected upstream of the electric drive machine and simultaneously charges the battery.

[0010] In this embodiment, the charging system enables the battery to be charged while the vehicle is ready to drive or while driving with the range extender. This means that alternating current is generated by the generator, which, when needed—preferably to extend the range of a journey already underway or to enable an upcoming journey in the first place—is driven by the combustion engine, consuming fuel in the process. The power output from the generator is diverted from the vehicle's electrical system, of which the charging system according to the invention is a part, preferably towards the electric drive motor. Alternatively, some of the output power is used to simultaneously charge the battery.

[0011] It can also be advantageous for the second AC output current to be rectified to a third DC output current by the first AC-DC converter and by the second AC-DC converter connected in parallel to the first AC-DC converter, and for the third DC output current to charge the battery.

[0012] According to the present description, the third direct current differs from the second direct current in particular in that the flow of the second direct current requires the operation of the range extender and the flow of the third direct current requires charging the vehicle at an alternating current source via the first charging plug.

[0013] According to a further embodiment of the present invention, the first AC-DC converter is designed for a maximum input power of at least 230 volts x 16 amperes and the second AC-DC converter is designed for a maximum input power of at least 230 volts x 16 amperes.

[0014] Such a system allows electric vehicle users, for example in North America, to connect their electric vehicles to differently specified but widely available AC charging networks. In North America, for instance, at least two AC power networks are common in residential settings: a 120-volt network protected by a continuous 16-ampere fuse and a 240-volt network protected by a continuous 32-ampere fuse. If the vehicle is connected to the higher-voltage network for charging, the battery charges more quickly compared to the lower-voltage network; this will be referred to as fast charging in the remainder of this document.

[0015] Additionally, the charging system preferably has the feature that the first direct current can be interrupted by a high-performance switch, in particular a DC contactor.

[0016] This allows the battery to be galvanically isolated from the DC charging station during the charging process, for example for high-voltage safety purposes.

[0017] Furthermore, the charging system according to the invention can be designed such that the second AC-DC converter and the DC contactor are geometrically integrated in a combination charging unit and the parallel connection of the first AC-DC converter with the second AC-DC converter is implemented outside the combination charging unit or on the combination charging unit.

[0018] This design offers particular advantages, especially for the vehicle manufacturer, in terms of a modular design for the vehicle's electrical system and / or the electric vehicle itself. For example, in this design, DC charging at a DC charging station can be offered as an optional extra, since this function and the necessary technical components are not essential for the functionality of the rest of the charging system. This would allow electric vehicles to be offered in different configurations, with DC charging available as an optional feature.If the vehicle is equipped with DC charging capability, another charging system configuration could omit the second AC-DC converter, allowing for the factory installation of a simplified version of the combined charging unit without the second converter. In this configuration, charging on the AC grid, based on the design of the first AC-DC converter, is limited to a maximum power of at least 230 volts x 16 amps, meaning fast charging is not possible. If the vehicle is primarily used in Europe or other countries or regions, or ordered from the manufacturer from these countries, the configuration with only one AC-DC converter is technically sufficient due to the limited availability of AC grids with higher output power.In these cases, the option of fast charging offers no technical benefit to the customer, meaning that a more cost-effective vehicle can be offered without any noticeable technical limitations. The modular design of the charging system according to the invention, hereinafter referred to as modularity, allows the vehicle manufacturer, as described, to offer various versions of the electric vehicle cost-effectively according to a modular system and to accommodate specific customer needs, e.g., in the form of optional equipment or country-specific variants, with minimal production effort. Furthermore, due to the specific embodiment of the charging system, it is conceivable that the range extender could also be considered optional and offered as special equipment.

[0019] Preferably, the combination charging unit, the first AC-DC converter, the first charging plug and the second charging plug are functionally controlled and monitored by at least one control unit.

[0020] In such a control unit or units, all necessary software components can be integrated to such an extent that the modularity of the charging system is not impaired. Typically, the software includes control functions, regulation functions, monitoring functions, and communication functions via data buses.

[0021] A particular embodiment is represented in that the first AC-DC converter, the combination charging unit, the AC-DC converter and the control unit are components of the electric vehicle.

[0022] This particular design offers the advantage, among others, that the charging infrastructure outside the vehicle, for example the DC charging station or the public AC grid, can be kept as technically simple as possible, or that the establishment of a conductive connection via charging cable primarily only needs to be geometrically possible.

[0023] The invention is based on the following considerations: For electric vehicles with rechargeable batteries, different charger variants are required depending on the country-specific charging capacity, for example, for DC charging, single-phase AC charging, or three-phase AC charging. Furthermore, the charging infrastructure, according to the current state of series development, is so volatile that it is not yet foreseeable which charging architectures will actually be viable in the future. Typically, a single-phase 3.5-kilowatt AC charger represents the current state of series development, possibly with the additional option of DC charging. A disadvantage of this technology is that DC charging stations are not widespread, particularly in the USA, and therefore charging would only be possible with the 3.5-kilowatt AC charger. Otherwise, additional charging variants would have to be developed, which in turn would not be necessary for other markets.Therefore, the standard equipment includes a 3.5 kilowatt AC charger, referred to here as the basic charger. An optional AC charger, referred to here as the comfort charger, can be ordered. This charger incorporates an additional 3.5 kilowatt AC charging unit that can be connected in parallel to the basic charger. This allows for an AC charging capacity of 7 kilowatts. The comfort charger may be identical in design to the basic charger. Furthermore, the comfort charger includes a device, referred to here as a contactor box, for switching high currents, which also enables high-power DC charging. For this to work, a separate DC charging socket in the vehicle must be able to be disconnected from the high-voltage system via the contactor box.This offers the advantage that combining the contactor box and the comfort charger eliminates the need to develop further charging architecture variants, as the described architecture provides flexible charging functions across different countries. This includes, for example, AC charging on the 32-amp AC grid in the USA, with the additional option of DC charging at a DC charging station.

[0024] The following describes a preferred embodiment of the invention with reference to the accompanying drawing. Further details, preferred embodiments, and further developments of the invention will be derived from this. In detail, the drawing schematically illustrates... Fig. 1: A block diagram of a system for charging a rechargeable battery of an electric vehicle.

[0025] The Fig. Figure 1 shows the electrical system architecture of an electric vehicle with a range extender. The range extender consists of an internal combustion engine (5), which can have a small number of cylinders and be operated at a fuel-efficiency and power-saving operating point, and a generator (4) that is mechanically driven by the internal combustion engine (5). The generator produces alternating current (3). The range extender preferably generates power when the vehicle is ready to drive, in order to extend the range during a journey or to enable driving in the first place. When the range extender is in operation, the power generated by the generator is fed to the inputs of two AC-to-DC converters (14, 15) connected in parallel. At the outputs, the resulting DC current (16) is typically used to power the electric machine (2), which converts the electrical power into mechanical power.For this purpose, an AC-DC converter (17) is connected upstream of the electric machine as an inverter, since the latter cannot be supplied with DC current on the input side. Depending on the possible power output of the range extender (4, 5) and the power requirement of the drive machine (17), the DC current (16) can alternatively be provided to charge the high-voltage battery (1), which is preferably implemented using lithium-ion technology as an electrochemical energy storage system. Other electrochemical energy storage systems, such as nickel-metal hydride batteries or lead-acid batteries, would also be conceivable. When the vehicle is switched off, i.e., when the electric vehicle is not ready to drive, the following applies: Fig. In the topology shown in Figure 1, the battery (1) can be charged via external electrical power sources, for example, the household AC power connection (8) or a DC charging station (13). Simultaneous charging at an AC power source (8) and a DC charging station (13) is also possible. Charging at an AC power source is achieved by connecting a suitable charging cable (9) to the vehicle's integrated charging socket (6). The supplied AC current (7) is rectified by the two AC-to-DC converters (14, 15), and the resulting DC current (18) charges the battery (1). The two AC-to-DC converters are designed for a maximum input power of at least 230 volts x 16 amperes. The DC charging station (13) is connected to the vehicle's integrated charging socket (10) via a suitable charging cable (11).The supplied direct current (12) charges the battery (1) and can be interrupted via a DC contactor (19), for example, for safety reasons or when the battery is fully charged. The DC contactor (19) and the AC-DC converter (15) are preferably housed in a casing referred to as the combination charging unit (20). Geometrically, the combination charging unit (20) is designed such that the AC-DC converter (15) is mechanically removable, for example, by clamps, screws, or a slide-in mechanism. This clearly demonstrates the modular design of the charging system. Thus, the electric vehicle can be delivered, for example, with or without the DC charging function, i.e., with or without the combination charging unit (20).If the vehicle is equipped with the DC charging function, it can still be delivered with or without the fast charging function, meaning with or without an AC-DC converter (15). In some countries, the AC-DC converter (14) does not reach its design power limit of at least 230 volts x 16 amps due to the power ratings of the public AC grid (8), as would be the case, for example, with the 120-volt AC grid common in the USA. For all these customers, the AC-DC converter (15) can be omitted to their cost advantage, allowing for a country-specific equipment option for the vehicle with or without the AC-DC converter (15). In this context, designing the AC-DC converter (14) to exceed 230 volts x 16 amps offers no functional advantage for many countries, but does represent a cost disadvantage.The range extender, meaning the combination of generator (4) and combustion engine (5), can also be offered as an option, independent of the variants described above. If the generator (4) and the combustion engine (5) are not installed in the vehicle, the alternating current (3) is omitted. Regardless of the selected variants, the charging system is regulated, controlled, and monitored by a control unit (21). The necessary communication paths, implemented via data buses, are described in [reference missing]. Fig. 1 is represented as dotted lines. Reference symbol list 1 rechargeable battery 2 electric drive motors 3 first output alternating current 4 Generator 5 Internal combustion engine 6 first charging plug device 7 second output alternating current 8 AC network 9 first charging cable 10 second charging plug device 11 second charging cable 12 first direct current 13 DC charging stations 14 first AC-DC converter 15 second AC-DC converter 16 second direct current 17 DC-AC converters 18 third direct current 19 DC contactors 20 combination charging units 21 Control unit

Claims

[1] System for charging a rechargeable battery (1) of an electric vehicle, wherein the electric vehicle is equipped with an electric drive motor (2), a generator (4) generating a first alternating current output (3), an internal combustion engine (5) driving the generator which can be started during the operation of the electric vehicle and a first electrical charging plug device (6), characterized by , - that when the combustion engine is started, the generator can be used at least temporarily as an electrical power source to supply the battery with charging power, - that the first charging plug device is geometrically designed in such a way that a single-phase AC network (8) supplying a second output alternating current (7) can be connected to the first charging plug device with a first charging cable (9) in order to supply the battery with charging power as an electrical power source when the electric vehicle is switched off, - that the first charging connector is designed for a load with a maximum electrical voltage of at least 240 volts and a maximum current of at least 32 amperes and - that a second electrical charging plug (10) is integrated into the electric vehicle, to which a DC charging station (13) supplying a first DC current (12) can be connected with a second charging cable (11) when the electric vehicle is parked, so that when the electric vehicle is parked the DC charging station can be used either exclusively or simultaneously with the single-phase AC network as an electrical power source to supply the battery with charging power. [2] System according to claim 1, characterized by, that the first output alternating current is rectified by a first AC-DC converter (14) and a second AC-DC converter (15) connected in parallel to the first AC-DC converter to a second direct current (16). [3] System according to claim 2, characterized by , that the second direct current either supplies the electric drive machine with electrical power through a direct current-to-alternating current converter (17) connected upstream of the electric drive machine, or that the second direct current supplies the electric drive machine with electrical power through the direct current-to-alternating current converter connected upstream of the electric drive machine and simultaneously charges the battery. [4] System according to claim 2, characterized by, that the second output alternating current from the first AC-DC converter and from the second AC-DC converter is rectified to a third DC current (18) and the third DC current charges the battery. [5] System according to claim 2, characterized by , that the first AC-DC converter is designed for a maximum input power of at least 230 volts x 16 amps and the second AC-DC converter is designed for a maximum input power of at least 230 volts x 16 amps. [6] System according to any one of claims 2 to 5, characterized by , that the first direct current can be interrupted by a high-performance switch, in particular a DC contactor (19). [7] System according to claim 6, characterized by, that the second AC-DC converter and the DC contactor are geometrically integrated in a combination charging unit (20) and the parallel connection of the first AC-DC converter with the second AC-DC converter is implemented outside the combination charging unit or on the combination charging unit. [8] System according to claim 7, characterized by , that the combination charging unit, the first AC-DC converter, the first charging plug and the second charging plug are functionally controlled and monitored by at least one control unit (21). [9] System according to claim 8, characterized by , that the first AC-DC converter, the combination charging unit, the AC-DC converter and the control unit are components of the electric vehicle.

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