Device for inductive or wired charging of an electric vehicle

Abstract

A device (1) for the inductive or wired charging of an electric vehicle (2) and having a mains connection for an AC voltage supply network (10), a rectifier (3) connected to the mains connection, which is designed to rectify an AC voltage received from the mains connection into a first DC voltage, an inverter (4) connected to the rectifier (3) and designed to inverter-convert the first DC voltage received from the rectifier (3), and a first charging outlet (20) connected to the inverter (4) for inductive charging, characterized by a galvanically isolated DC / DC converter (17) which is connected on the input side to the rectifier (3) and on the output side to a second charging outlet (18) for wired charging and is designed to convert the first DC voltage into a second DC voltage and output it to the second charging outlet (18).

Description

Technical area

[0001] The invention relates to a device for the inductive (wireless) or wired charging of an electric vehicle. Technical background

[0002] Passenger and truck transport are to be decarbonized over the coming years and decades for well-known reasons. Various technologies are available for charging battery-powered electric vehicles, namely AC charging, DC charging, and inductive charging. With AC charging, a charger is permanently installed on board the electric vehicle. This charger receives alternating current, rectifies it, and converts it into a charging voltage suitable for the current charge level of the electric vehicle's traction battery. The disadvantage of this approach is that every vehicle requires a built-in charger. This is offset by the fact that AC voltage is available almost everywhere via the power grid.With DC charging, the required DC voltage is transmitted from the electric vehicle to the (external) charging device, which then generates this DC voltage as the charging voltage for the traction battery and outputs it to the electric vehicle. DC charging is expected to prevail over AC charging in the medium term. Both AC charging and DC charging are wired charging technologies.

[0003] During inductive or wireless charging, the energy is transferred inductively from a ground coil via an air gap to a secondary coil installed at a suitable location in the electric vehicle.

[0004] This eliminates the need to plug a charging connector into the electric vehicle, as is required for both AC and DC charging. This increases convenience while also opening up the possibility of short-term charging, for example, when stopping at a traffic light. A small number of electric vehicles are already available on the market that can be charged inductively. This number is expected to steadily increase over the coming years.

[0005] The invention aims to introduce a novel charging device for charging an electric vehicle. The invention achieves this objective by means of a device according to claim 1. The subclaims specify particularly advantageous embodiments of the invention. Summary of the invention

[0006] The invention introduces a novel device for the inductive or wired charging of an electric vehicle. The device is equipped with a mains connection for an AC voltage supply network, a rectifier connected to the mains connection, an inverter connected to the rectifier, and a first charging outlet for inductive charging connected to the inverter. The rectifier is designed to rectify an AC voltage received from the mains connection into a first DC voltage. The inverter is designed to invert the first DC voltage received by the rectifier.According to the invention, the device also has a galvanically isolated DC / DC converter which is connected on the input side to the rectifier and on the output side to a second charging outlet for wired charging and is designed to convert the first DC voltage into a second DC voltage and output it to the second charging outlet.

[0007] Given the increasing market penetration of wireless charging technologies in the electric vehicle market, which the inventors expect, the invention has the advantage of offering backward compatibility for existing older electric vehicles without the option of wireless charging, or conversely, forward compatibility for an inductively chargeable electric vehicle acquired at a later date, at low cost and without duplication of effort. An older electric vehicle can be charged via cable using the device according to the invention, for which purpose the device according to the invention can provide a direct voltage for direct voltage charging requested by the electric vehicle via the DC / DC converter. The additional circuitry required for this is limited to the DC / DC converter and the second charging output, because all other components are required for wireless charging anyway.When purchasing an inductively charging electric vehicle, a ground coil can be connected to the first charging outlet without having to replace the device. In this case, the additional effort for forward compatibility lies in the inverter and the first charging outlet.

[0008] Preferably, the device has a ground coil connected or connectable to the first charging outlet, which is designed to wirelessly transmit electrical energy received from the inverter to a secondary coil of the electric vehicle. The ground coil connection can be detachable via a plug / socket system or fixed (after the initial connection has been established, for example, by screwing or snapping in place). In the first case, the charging outlet is preferably designed as a socket.

[0009] The second charging outlet can be configured either as a connection for a charging cable or as a charging cable permanently connected to the DC / DC converter and a charging plug located at a free end of the charging cable. In the latter case, the charging plug can be, in particular, a Combined Charging System charging plug, a North American Charging Standard charging plug, or a CHAdeMO charging plug.

[0010] Particularly preferably, the device has a communication unit configured to establish a first wireless communication channel to the electric vehicle and a second wired communication channel to another electric vehicle connected to the second charging outlet. The communication unit can thus be used to control both an inductive charging process via the ground coil and a wired charging process via the second charging outlet, thereby eliminating the need for a separate unit for the DC charging supported by the invention for reasons of backward compatibility. In particular, the communication unit can be configured as a charging controller on the charger side.

[0011] The communication unit can be configured to transmit a positioning signal containing information about an overlap between the ground coil and the secondary coil via the first communication channel. The positioning signal can be received by an electric vehicle and used to position the secondary coil of the electric vehicle as precisely as possible over the ground coil of the device according to the invention by appropriately maneuvering the electric vehicle.

[0012] The device can be equipped with an object detection device configured to detect an object located between the ground coil and the secondary coil and, depending on the detection result, to output an enable signal to the inverter. The object detection device ensures that such an object is not affected by the strong fields used in inductive charging. These fields can lead to heating of metallic or living objects, which must be avoided.

[0013] Particularly preferably, the inverter is designed to generate an alternating voltage with a frequency between 70 and 100 kilohertz, preferably between 80 and 90 kilohertz, particularly preferably at least approximately 85 kilohertz. Alternating voltages in these frequency ranges and with the desired electrical power can be reliably generated using available power electronic components.

[0014] In versions with a ground coil, the device preferably has a frequency adjustment unit connected between the inverter and the ground coil, which is designed to variably adjust a resonant frequency. The frequency adjustment unit can, for example, contain a network of switchable and switchable capacitors and / or coils. It serves to tune the resonant frequency of the system consisting of the primary side (charging device according to the invention), air gap, and secondary side (electric vehicle). The resonant frequency depends on the spatial overlap between the primary-side ground coil and the vehicle-side coil, as well as the dimensions of the air gap between the two coils. These parameters are subject to significant fluctuations when the electric vehicle is parked over the ground coil.However, the charging arrangement consisting of the charging device and the electric vehicle achieves the best efficiency when operated at the resonant frequency; on the other hand, the inductive energy transfer should occur at a predetermined frequency. The frequency adjustment unit therefore serves to compensate for the changing inductance and the resulting change in the resonant frequency of the arrangement and to return it to the desired, predetermined frequency value, for example, 85 kHz. In this context, the use of the frequency adjustment unit leads to improved energy efficiency.

[0015] The device can be equipped with a buffer capacitor connected between a first connecting pole and a second connecting pole, with the first and second connecting poles connecting the rectifier, the inverter, and the DC / DC converter. The buffer capacitor serves to smooth the voltage output by the rectifier and to reserve energy for the (usually pulsed) operation of the inverter and DC / DC converter.

[0016] Particularly preferably, in embodiments with a ground coil, the device according to the invention has a first housing, a second housing and a connecting cable extending from the first housing to the second housing. At least the rectifier, the DC / DC converter, the first charging outlet and the second charging outlet are arranged in or on the first housing and at least the ground coil is arranged in the second housing. The first housing is designed for attachment to a vertical surface and the second housing is designed for attachment to a horizontal surface. The inverter can be arranged optionally in the first or the second housing. In the former case, the connecting cable is designed as a high-frequency cable for transmitting the comparatively high alternating voltage generated by the inverter to the ground coil.In the latter case, the connecting cable can be a simple cable for a supply voltage, since the change to the alternating voltage only takes place in the second housing.

[0017] Particularly preferably, the rectifier and inverter are designed without galvanic isolation, which significantly reduces material requirements. Galvanic isolation, desired for safety reasons, is achieved during inductive charging by the design with a base coil and secondary coil. For DC charging, the DC / DC converter is designed with galvanic isolation according to the invention. Short description of the characters

[0018] The invention is explained in more detail below with reference to exemplary embodiments. They show: Fig. 1 shows a first embodiment of a device according to the invention with electric vehicles connected for charging; and Fig. 2 a second embodiment of a device according to the invention. Detailed description of the characters

[0019] Fig. 1 shows a first exemplary embodiment of a device 1 according to the invention with two electric vehicles 2 connected for charging. Typically, only one electric vehicle 2 will be connected to the charging device 1 at a time, so that the charging device 1 is used either for inductive charging of one electric vehicle 2 shown or for wired DC charging of the other electric vehicle 2 shown. The charging device 1 can be designed to charge only one electric vehicle 2 at a time in order to enable a cost-effective power-electrical design of the components of the charging device 1 used jointly for both charging types. Conversely, it is conceivable to design the charging device 1 according to the invention such that the two electric vehicles 2 can be charged simultaneously, thus offering maximum convenience for households with two electric vehicles.

[0020] In Fig. Figure 1 shows one of the two electric vehicles 2 as a block diagram to better illustrate the functionality of inductive charging and the interaction of the components used. The other electric vehicle 2, however, is only shown schematically, since the DC charging used for this electric vehicle 2 requires only minimal circuitry, which—except for measurement and safety components—can also be designed differently depending on the model.

[0021] The charging device 1 is connected via a corresponding connection to an AC voltage supply network 10, which provides the energy required for charging the electric vehicle 2 or the electric vehicles 2. With a bidirectional design of the charging device 1, electrical energy from the electric vehicle 2 can also be fed back into the AC voltage supply network 10 in order to compensate for fluctuations in the supply of electrical energy in the AC voltage supply network 10.

[0022] The charging device 1 has a rectifier 3, which is fed from the AC power supply network 10 and rectifies the AC voltage received from the AC power supply network into a DC voltage. The rectifier 3 is connected on the output side to an inverter 4, which converts the DC voltage generated by the rectifier 3 into a high-frequency AC voltage. For example, the AC voltage can have a frequency between 80 and 100 kilohertz, preferably at least approximately 85 kilohertz.

[0023] In the present exemplary embodiment, the alternating voltage generated by the inverter 4 is output via a frequency adjustment unit 5 to a ground coil 6 connected to a first charging outlet 20, which inductively transmits the electrical energy received via the chain of rectifier 3, inverter 4, and the (optional) frequency adjustment unit 5 to the electric vehicle 2. The frequency adjustment unit 5 can contain a network of switchable capacitors and / or coils and serves to tune the resonant frequency of the system comprising the primary side (charging device 1), air gap, and secondary side (electric vehicle 2). The resonant frequency or the impedance of the arrangement depends on the spatial overlap between the primary-side ground coil 6 and the vehicle-side coil, as well as the dimensions of the air gap between the two coils.

[0024] These parameters are subject to significant fluctuations when the electric vehicle 2 is parked above the ground coil 6. However, the charging arrangement comprising charging device 1 and electric vehicle 2 operates at its most efficient level at the resonant frequency; on the other hand, the inductive energy transfer should occur at a predetermined frequency. The frequency adjustment unit 5 therefore serves to compensate for the changing inductance and the resulting change in the resonant frequency of the arrangement and to return it to the desired, predetermined frequency value, for example, 85 kHz. In this context, the use of a frequency adjustment unit 5 leads to improved energy efficiency.

[0025] The inductively chargeable electric vehicle 2 is in Fig. 1 is shown as an example and reduced to its components intended for the inductive charging process. Its exact structure is not particularly relevant to the subject matter of the invention, but will be briefly explained for a better understanding.

[0026] The inductively chargeable electric vehicle 2 from Fig. 1 comprises a secondary coil 11 for receiving the inductively transmitted electrical energy, a vehicle-mounted frequency adjustment unit 12, a vehicle-mounted rectifier 13 for rectifying the electrical energy received as high-frequency alternating voltage, and a battery charger, which in the example shown is designed as a DC / DC converter 14 and is connected downstream of the traction battery 15 of the electric vehicle 2. Alternative designs may be known from the prior art.

[0027] The device 1 according to the invention has a galvanically isolating DC / DC converter 17, which serves to convert the DC voltage generated by the rectifier 4, the magnitude of which is essentially determined by the amplitude of the AC voltage of the AC voltage supply network 10, into a (charging) DC voltage requested by an electric vehicle for DC charging. The requested DC voltage is adapted to the respective instantaneous state of charge of the traction battery of the electric vehicle 2 to be charged via cable. In general, the higher the state of charge of a battery, the higher the DC voltage required to continue charging the battery.The electric vehicle 2, which knows the state of charge of its traction battery, therefore requests a suitable DC charging voltage for a particular time, which the device 1 provides via the DC / DC converter 17 and a second charging output 18 connected to its output.

[0028] The second charging outlet 18 can be designed as a socket for a charging cable or - as in Fig. 1 - comprise a charging cable 19 permanently connected to the DC / DC controller 17 and a charging plug 20 arranged at a free end of the charging cable 19.

[0029] With common charging technologies, as already mentioned above, parameters of the charging process are negotiated at the beginning of the session between the charging device and the electric vehicle. For this purpose, communication is established between the charging device and the electric vehicle. The charging device 1 according to the invention has a communication unit 7 for this purpose, which can establish a first (wireless) communication channel 8 to a corresponding vehicle-side communication unit 16 and a second (wired) communication channel 9 to an electric vehicle 2 connected to the second charging outlet 18. The first communication channel 8 can be operated by suitable modulation of a signal transmitted between the ground coil 6 and the secondary coil 10 or on the basis of another type of wireless communication such as Bluetooth or WLAN.The second communication channel 9 is preferably handled via established communication standards intended for DC charging, such as ISO 15118, which provide communication via the charging cable. The communication unit 7 is also connected to the inverter 4 and the DC / DC converter 17 in order to transmit the parameters relevant for the inductive or wired energy transmission, which have been negotiated with the corresponding electric vehicle 2.

[0030] Fig. Figure 2 shows a second embodiment of a device 1 according to the invention, wherein in this embodiment, the spatial arrangement of the functional units of the charging device 1 according to the invention forms the main aspect of the illustration. In a first housing 21, which is designed and provided for attachment to a vertical surface such as a post or a wall, at least the rectifier 3, the communication unit 7, the DC / DC converter 17, the first charging outlet 20 and the second charging outlet 18 are arranged. In the Fig.In the example shown in Figure 2, the second charging outlet 18 is again illustrated as being configured with a charging cable 19 permanently connected to the charging device and a charging plug 20. The first housing 21 preferably has a holder (not shown) for the charging plug 20 so that it can be kept handy when not plugged into an electric vehicle. For example, the holder can be designed to mimic the shape of a charging socket, so that the charging plug 20 can be plugged into the holder like the charging socket of an electric vehicle and then held by the holder.

[0031] The functional units arranged in the first housing 21 are connected via a connecting cable 23 connected to the first charging outlet 20 to a second housing 22, in which at least the ground coil 6 of the device 1 is arranged. In principle, it is possible to arrange the inverter 4 and the frequency adjustment unit 5 in the second housing 22. In this case, the connecting cable 23 can be designed as a relatively simple cable for a direct voltage. However, the disadvantages here are the increased space requirement in the second housing 22 and the more difficult cooling. Therefore, it is alternatively also possible to arrange the inverter 4 and the frequency adjustment unit 5 in the first housing 21, in which case the connecting cable 23 should be designed as a high-frequency cable in order to keep the losses during the transport of the high-frequency power signal to be transmitted from the ground coil 6 to a minimum.

[0032] The invention has been explained in more detail with reference to illustrations of preferred embodiments. These embodiments are provided solely for the purpose of better understanding and are not intended to limit the scope of the invention, which is defined exclusively by the following claims. List of reference symbols 1 charging device 2 electric vehicles 3 rectifiers 4 inverters 5 Frequency adjustment unit 6 ground coil 7 Communication unit 8 first communication channel 9 second communication channel 10 AC power supply network 11 Secondary coil 12 vehicle-side frequency adjustment unit 13 vehicle-side rectifier 14 DC / DC controllers 15 Traction battery 16 vehicle-side communication unit 17 DC / DC controllers 18 second charging outlet 19 charging cables 20 first loading exit 21 first housing 22 second housing 23 connecting cables

Claims

[1] A device (1) for the inductive or cable-based charging of an electric vehicle (2) and having a mains connection for an AC voltage supply network (10), a rectifier (3) connected to the mains connection, which is designed to rectify an AC voltage received from the mains connection into a first DC voltage, an inverter (4) connected to the rectifier (3) and designed to convert the first DC voltage received from the rectifier (3), and a first charging outlet (20) connected to the inverter (4) for inductive charging, characterized by a galvanically isolated DC / DC converter (17) which is connected on the input side to the rectifier (3) and on the output side to a second charging outlet (18) for wired charging and is designed to convert the first DC voltage into a second DC voltage and output it to the second charging outlet (18). [2] The device (1) of the preceding claim, with a ground coil (6) connected or connectable to the first charging outlet (20), which is designed to wirelessly transmit electrical energy received from the inverter (4) to a secondary coil (11) of the electric vehicle (2). [3] The device (1) of one of the preceding claims, in which the second charging outlet (18) is designed as a connection for a charging cable (19). [4] The device (1) of one of claims 1 or 2, wherein the second charging outlet (18) is designed as a charging cable (19) fixedly connected to the DC / DC controller (17) and a charging plug (20) arranged at a free end of the charging cable (19). [5] The device (1) of the preceding claim, wherein the charging plug (20) is a Combined Charging System charging plug, a North American Charging Standard charging plug or a CHAdeMO charging plug. [6] The device (1) of one of the preceding claims, comprising a communication unit (7) which is designed to establish a first wireless communication channel (8) to the electric vehicle (2) and a second wired communication channel (9) to a further electric vehicle (2) connected to the second charging outlet (18). [7] The device (1) of the preceding claim, in which the communication unit (7) is designed to send a positioning signal via the first communication channel (8) which contains information about an overlap of the ground coil (6) and the secondary coil (11). [8] The device (1) of one of the preceding claims, in which the inverter (4) is designed to generate an alternating voltage with a frequency between 70 and 100 kilohertz, preferably between 80 and 90 kilohertz, particularly preferably of at least approximately 85 kilohertz. [9] The device (1) of claim 2 or of claim 2 and one of claims 3 to 8, with a frequency adjustment unit (5) connected between the inverter (4) and the ground coil (6), which is designed to variably set a resonance frequency. [10] The device (1) of any one of the preceding claims, comprising a buffer capacitor connected between a first connecting pole and a second connecting pole, wherein the first and second connecting poles interconnect the rectifier (3), the inverter (4) and the DC / DC converter (17). [11] The device (1) of claim 2 or of claim 2 and one of claims 3 to 10, with a first housing (21), a second housing (22) and a connecting cable (23) extending from the first housing (21) to the second housing (22), wherein at least the rectifier (3), the DC / DC converter (17), the first charging outlet (20) and the second charging outlet (18) are arranged in or on the first housing (21) and at least the ground coil (6) is arranged in the second housing (22), and wherein the first housing (21) is designed for attachment to a vertical surface and the second housing (22) is designed for attachment to a horizontal surface. [12] The device (1) of one of the preceding claims, in which the rectifier (3) and the inverter (4) are designed without galvanic isolation.

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