Motor vehicle

Abstract

The invention relates to a motor vehicle (26) designed as a hybrid or electric vehicle (26) and comprising a drive battery (16) and an electric motor (18) for generating propulsion, wherein said motor vehicle has a receiving unit (12) for inductively transmitted energy and a rectifier (14) connected downstream of the receiving unit (12), wherein said motor vehicle is designed for an operating mode in which inductively transmitted energy is received during driving operation, and wherein an energy buffer (28) is connected between the rectifier (14) and the drive battery (16).

Description

[0001] The invention relates to a motor vehicle which is designed as a hybrid or electric vehicle.

[0002] The prevalence of electric vehicles has increased significantly recently, and it is expected that their prevalence will continue to grow in the near future. The same applies to hybrid vehicles, at least those that, like electric vehicles, are designed to be charged via an external energy source.

[0003] For charging via an external energy source, such motor vehicles have an interface through which the respective vehicle can be connected to an external energy source. Currently, such interfaces are typically implemented as a connector, as described, for example, in DE 10 2016 209 898 A1.

[0004] However, interfaces for wireless / contactless power transmission are also known. Here, the connection between the vehicle and the external power source is established through an inductive coupling.

[0005] Such wireless / contactless energy transfer can also be used to charge a motor vehicle while driving. Corresponding charging methods are described, for example, in US 2017 / 0 334 296 A1 and US 2017 / 0 136 911 A1.

[0006] The invention is based on the object of specifying a motor vehicle which is advantageously designed as a hybrid or electric vehicle.

[0007] This object is achieved by a motor vehicle having the features of patent claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the dependent patent claims.

[0008] According to at least one preferred embodiment, the motor vehicle according to the invention is designed as a so-called commercial vehicle. Independently of this, it is also designed as a hybrid or electric vehicle.

[0009] It features a so-called drive battery, also called a traction battery, and an electric motor for generating propulsion. The drive battery typically has a nominal voltage greater than or equal to 100 V, and in particular greater than or equal to 200 V, and is implemented, for example, as a lithium-ion battery.

[0010] The motor vehicle further comprises a receiving unit for inductively transmitted energy and a rectifier connected downstream of the receiving unit. The receiving unit expediently forms an interface via which the motor vehicle can be connected to an external energy source, in particular for charging the motor vehicle via the external energy source. The interface is designed for wireless / contactless energy transmission, in which a connection between the motor vehicle and an external energy source can be established by inductive coupling. In a preferred embodiment, the receiving unit is also designed for resonant inductive coupling. Independently of this, the receiving unit typically comprises a conductor loop or receiver coil.

[0011] Furthermore, the motor vehicle is configured for an operating mode in which inductively transmitted energy is received during driving. This operating mode is therefore also referred to below as the receive operating mode. The inductively transmitted energy, which is conveniently received by the receiving unit, is then used, in particular, to inductively charge the motor vehicle.

[0012] The basic concept for charging a motor vehicle while driving is known in principle and is outlined, for example, in US 2017 / 0 334 296 A1 and US 2017 / 0 136 911 A1.

[0013] This basic concept is now preferably followed at least to the extent that the motor vehicle, i.e., the motor vehicle according to the invention, is typically designed such that it can be connected to an external energy source, which is configured as a so-called inductive roadway. Such an inductive roadway typically comprises several transmitting units distributed along the road, each transmitting unit typically comprising a conductor loop or transmitting coil and emitting energy during operation.

[0014] The receiving unit, in turn, is usually designed in such a way that it can be inductively coupled to each of these transmitting units and that, with sufficient coupling between the receiving unit and one of the transmitting units, it receives at least part of the energy emitted by the corresponding transmitting unit as inductively transmitted energy.

[0015] To implement the aforementioned operating mode, i.e., the receive operating mode, the motor vehicle is then typically further configured such that, when driving along a corresponding induction road with activated transmitting units, the receiving unit in the receive operating mode forms an inductive coupling with one transmitting unit after the other in a temporal sequence, each time for a limited time, and receives inductively transmitted energy during each inductive coupling. When driving along the induction road, the receiving unit typically receives an energy pulse from each transmitting unit, with the individual energy pulses being received at staggered intervals, i.e., as a sequence of energy pulses.

[0016] Furthermore, the motor vehicle is expediently configured such that, in the aforementioned receive operating mode, an alternating current is generated in the receiving unit by inductively transmitted energy, which is fed to the rectifier connected downstream of the receiving unit. The rectifier, in turn, then generates a direct current, fed by the alternating current. This direct current can be used, for example, to charge the drive battery and thus the motor vehicle. Depending on the application, this direct current is then actually used to charge the drive battery and thus the motor vehicle, namely in a charging operating mode. The charging operating mode is expediently a special form of the receive operating mode.

[0017] However, charging does not occur by directly feeding the direct current generated by the rectifier to the drive battery. Instead, the motor vehicle is designed so that an intermediate energy storage device is connected between the rectifier and the drive battery.

[0018] The buffer typically serves as a type of energy buffer, allowing energy peaks to be safely absorbed and temporarily stored. The absorbed and temporarily stored "excess" energy can then be released again during power pauses. In this context, reference should be made again to the previous explanations, according to which the energy transfer to the receiver unit is typically pulsed. This is because the inductive energy transfer and the travel via the "static" transmitting units / transmitters usually only result in energy being transferred when the receiver unit / receiver is positioned over a transmitting unit / transmitter. No energy is transferred during the intermediate pauses. This leads to pulsed energy transfer. As a result, the electrical power that can be used to charge the vehicle also changes significantly over time.With the intermediate storage, at least a certain amount of compensation can be achieved, so that the “alternating power” is converted into a uniform power that is more favorable for the vehicle.

[0019] The following should be noted in addition: The aforementioned energy pulse typically represents a "phase of inductive energy transfer," i.e., a period in which the overlap between the receiver and one of the transmitters is sufficiently high. The aforementioned energy peaks arise, in particular, because the receiver is moved from one transmitter to the next during the traverse of the inductive path, and thus cannot receive any power in between.

[0020] It should also be noted that during such a "phase of inductive energy transfer," the energy transfer is conveniently carried out using alternating current with a high frequency (e.g., 100 kHz). Therefore, an energy pulse referred to above typically comprises "several smaller pulses."

[0021] The aforementioned more uniform power is then typically also advantageous for a so-called battery management system (BMS). The motor vehicle preferably includes such a battery management system. Furthermore, the motor vehicle preferably includes a control device that is signal-connected to the battery management system.

[0022] The battery management system is typically designed to evaluate the internal condition of the drive battery (e.g., state of charge, temperature, etc.) and transmit the corresponding evaluation to the control device of the motor vehicle. This allows the control device to, for example, control a "current release"—both in the charging and discharging directions—depending on this evaluation, for which the control device is preferably configured. The control device also typically has the task of maintaining predefined limits of the drive battery in order to prevent damage to the drive battery. Accordingly, the control device is preferably configured for this task.

[0023] This includes, for example, that in the case of a discharged drive battery, the electric motor must not draw more power from the vehicle system than can be supplied by the drive battery, whereby other auxiliary consumers (such as a high-voltage heater) must also be taken into account. In the case of a charging situation, this means, for example, that the electric motor's recuperation ("energy recovery") during braking must be regulated in such a way that the drive battery is not overcharged.

[0024] Irrespective of this, the motor vehicle is typically equipped for the aforementioned recuperation during braking.

[0025] In any case, the motor vehicle is designed in such a way that an intermediate energy storage device is connected between the rectifier and the drive battery, as already explained above.

[0026] The energy buffer is typically designed for an energy content of at least 0.1 Wh and in particular for an energy content of at least 0.3 Wh. Preferably, the energy buffer is also designed for an energy content of at least 1 Wh, more preferably for an energy content of at least 5 Wh and in particular for an energy content of at least 15 Wh.

[0027] Irrespective of this, the energy buffer is usually designed for an energy content of maximum 450 Wh, for an energy content of maximum 400 Wh or for an energy content of maximum 300 Wh. Preferably, the energy buffer is designed for an energy content of maximum 200 Wh and in particular for an energy content of maximum 100 Wh.

[0028] In addition, the energy buffer is typically designed for a maximum charging voltage of at least 20 V, for a maximum charging voltage of at least 50 V or for a maximum charging voltage of at least 100 V. Preferably, the energy buffer is also designed for a maximum charging voltage of approximately 400 V or approximately 800 V or approximately 900 V.

[0029] It is also advantageous if a DC-DC converter is interposed between the energy buffer and the traction battery. Thus, the motor vehicle then has the DC-DC converter in addition to the energy buffer. The DC-DC converter is typically designed to convert a higher input voltage Ue at the input of the DC-DC converter into a lower output voltage Ua at the output of the DC-DC converter. The input of the DC-DC converter is then usually connected to the energy buffer, and the output to the traction battery.

[0030] The interconnection of the energy buffer on the one hand and the DC-DC converter on the other hand creates, among other things, additional flexibility with regard to the voltage level at the receiving unit. This is certainly advantageous, because the transmittable power is limited, among other things, by the current, which in turn means higher power at a higher voltage level.

[0031] Depending on the application, various design variants of the energy buffer are advantageous. According to at least one design variant, the energy buffer comprises a rechargeable battery cell or a number of interconnected rechargeable battery cells. Alternatively or additionally, the energy buffer comprises a capacitor or a number of interconnected capacitors. Alternatively or additionally, the energy buffer comprises a supercapacitor or a number of interconnected supercapacitors.

[0032] If the energy buffer has a capacitor or a number of interconnected capacitors or a supercapacitor or a number of interconnected supercapacitors, the energy buffer preferably has an electrical (total) capacitance whose value is preferably greater than or equal to 1 mF, more preferably greater than or equal to 10 mF and in particular greater than or equal to 1F.

[0033] Independently of this, depending on the application, the motor vehicle is configured for an alternative or additional reception operating mode in which the traction battery is not charged, but instead electrical energy is supplied to the electric motor. This means that in this alternative or additional reception operating mode, electrical energy from the energy buffer or from the DC-DC converter is not supplied to the traction battery, but instead to the electric motor. This alternative or additional reception operating mode is also referred to below as the traction operating mode, and in this traction operating mode, additional charging losses in the traction battery can be avoided.

[0034] It is also useful if the motor vehicle is configured for an alternative or additional reception operating mode in which the traction battery is charged and electrical energy is supplied to the electric motor. This alternative or additional reception operating mode is also referred to below as a mixed operating mode.

[0035] Irrespective of this, it is always possible that the motor vehicle will brake, for example, because the traffic situation or traffic flow influences the choice of vehicle speed. During such braking, electrical energy is generated, preferably through recuperation. This, along with the inductively transmitted energy, is expediently taken into account during control by the aforementioned control device, particularly to prevent overcharging of the drive battery. The control device then only permits inductive energy transfer, for example, if the permissible charging current to the drive battery is higher than the expected current resulting from the inductive energy transfer.

[0036] Depending on the application, the motor vehicle is further configured to transmit a request or command to a previously described external energy source via a transmitting and receiving unit of the motor vehicle, which is suitable for starting or stopping an inductive transmission of energy by the external energy source. Alternatively, the motor vehicle is configured to start and stop the inductive transmission itself, in particular by reducing or increasing the voltage at the receiving unit.

[0037] In any case, the motor vehicle preferably does not include a device that enables control of the inductively transmitted energy during inductive charging. Therefore, the inductive transmission of energy is preferably not controlled, but typically only started and stopped.

[0038] Further advantages, features, and details of the invention will become apparent from the claims, the following description of preferred embodiments, and the schematic drawings, which show: Fig. 1 shows a top view of a charging system with an induction line and an electric vehicle according to the state of the art, Fig. 2 a receiving unit of the electric vehicle according to the state of the art, Fig. 3 shows a block diagram of the charging system according to the state of the art, and Fig. 4 shows a block diagram of a charging system according to the invention.

[0039] Corresponding parts are provided with the same reference numerals in all figures.

[0040] A charging system 2, which enables charging of an electric vehicle 4 while driving, is known in principle and a corresponding design according to the state of the art is described in Fig. 1. This charging system 2 includes the electric vehicle 4 and an induction line 6.

[0041] The induction line 6 comprises a plurality of transmitting units 8, which are controlled by a transmitting control unit 10 and supplied with electrical energy during transmission. The transmitting units 8 are designed for inductive energy transmission during transmission and each comprise, for example, a transmitting coil.

[0042] The electric vehicle 4, in turn, has a receiving unit 12 designed to receive inductively transmitted energy. Such a receiving unit 12 according to the prior art is described in Fig. 2 and has, for example, a receiving coil.

[0043] If the electric vehicle 4 now travels over the induction track 6, an inductive coupling is formed between the receiving unit 12 and the corresponding transmitting unit 8 each time the receiving unit 12 is positioned over one of the transmitting units 8, and energy is transferred inductively during the inductive coupling. As the vehicle travels over the induction track 6, energy is then transferred inductively in pulses.

[0044] The inductively transmitted energy received by the receiving unit 12 generates an alternating current in the receiving unit 12, which is fed to a rectifier 14 in the motor vehicle 4. In Fig. This is indicated in Figure 3. Here, the charging system 4 is shown in a block diagram according to the state of the art.

[0045] Fed by the alternating current, the rectifier 14 generates a direct current, which is ultimately used in a first operating mode to charge a drive battery 16. In a second operating mode, the direct current is used to power an electric motor 18 to generate propulsion, with the direct current in this case being fed to an inverter 20 connected upstream of the electric motor 18.

[0046] The change between the first operating mode and the second operating mode is controlled by a control device 22 of the electric vehicle 4. This control device is also configured to control the rectifier 14 and the inverter 20.

[0047] In Fig.Figure 4 shows an exemplary embodiment of a charging system 24 according to the invention. This differs from the prior art charging system 2 in the design of the electric vehicle 26, which additionally includes an energy buffer 28 and a DC-DC converter 30.

[0048] The energy buffer 28 is connected downstream of the rectifier 14 and thus interposed between the rectifier 14 and the drive battery 16. The DC-DC converter 30 is in turn connected downstream of the energy buffer 28 and thus interposed between the energy buffer 28 and the drive battery 16.

[0049] In the electric vehicle 26, the control device 22 is configured not only to control the change between the first operating mode and the second operating mode and the rectifier 14 and the inverter 20, but also to control the DC-DC converter 30.

[0050] In the exemplary embodiment, the energy buffer 28 is designed for an energy content of at least 1 Wh. In addition, the energy buffer 28 is designed for an energy content of a maximum of 100 Wh.

[0051] Independently of this, the energy buffer 28 is typically designed for a maximum charging voltage of at least 400 V.

[0052] Depending on the application, the energy buffer 28 also has two or more interconnected supercapacitors. List of reference symbols 2 Charging system 4 electric vehicle 6 Induction road 8 Transmitter unit 10 Transmission control unit 12 Receiving unit 14 rectifiers 16 traction battery 18 electric motor 20 inverters 22 Control device 24 charging system 26 electric vehicles 28 energy storage units 30 DC-DC converters QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 209 898 A1

[0003] US 2017 / 0 334 296 A1 [0005, 0012] US 2017 / 0 136 911 A1 [0005, 0012]

Claims

[1] Motor vehicle (26) designed as a hybrid or electric vehicle (26) and comprising a drive battery (16) and an electric motor (18) for generating propulsion, wherein - it has a receiving unit (12) for inductively transmitted energy and a rectifier (14) connected downstream of the receiving unit (12), - it is set up for an operating mode in which inductively transmitted energy is received during driving, and - an energy buffer (28) is connected between the rectifier (14) and the drive battery (16). [2] Motor vehicle (26) according to claim 1, wherein the energy buffer (28) is designed for an energy content of at least 5 Wh. [3] Motor vehicle (26) according to claim 1 or 2, wherein the energy buffer (28) is designed for an energy content of maximum 400 Wh. [4] Motor vehicle (26) according to one of claims 1 to 3, wherein the energy buffer (28) is designed for a maximum charging voltage of at least 50 V. [5] Motor vehicle (26) according to one of claims 1 to 4, wherein a DC-DC converter (30) is interposed between the energy buffer (28) and the drive battery (16). [6] Motor vehicle (26) according to one of claims 1 to 5, wherein the energy buffer (28) comprises an accumulator cell or a number of accumulator cells connected to one another. [7] Motor vehicle (26) according to one of claims 1 to 6, wherein the energy buffer (28) comprises a capacitor or a number of capacitors connected to one another. [8] Motor vehicle (26) according to one of claims 1 to 7, wherein the energy buffer (28) comprises a supercapacitor or a number of supercapacitors connected to one another. [9] Motor vehicle (26) according to one of claims 1 to 8, wherein a device is omitted by means of which a regulation of the inductively transmitted energy quantity is made possible during the reception of inductively transmitted energy.

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