WO2013127445A1

WO2013127445A1 - Charging system for the galvanically separated charging of an electrical energy accumulator of a vehicle, electrically powered vehicle, charging station for a vehicle, and corresponding method

Info

Publication number: WO2013127445A1
Application number: PCT/EP2012/053398
Authority: WO
Inventors: Monika POEBL; Richard Roskosch; Claus Seisenberger; Hans WÜNSCHE
Original assignee: Siemens Aktiengesellschaft
Priority date: 2012-02-29
Filing date: 2012-02-29
Publication date: 2013-09-06
Also published as: CN204659475U; DE112012005961A5

Abstract

The aim of the invention is to a solution for the galvanically separated charging of an energy accumulator of an electrically powered vehicle (3) in a safe and reliable way. In order to achieve said aim, the invention relates to a charging system (1) comprising a primary unit (7) outside the vehicle that has a primary coil for emitting electrical power and also a secondary unit (5) on the vehicle that has a secondary coil coupled to the energy accumulator (2) for receiving the power. At least one sensor coil arrangement (13) is provided with at least one sensor coil (15) which serves for detection of an electrically conductive foreign body (11) located in a power transmission region (10) between the primary unit (7) and the secondary unit (5). An electronic evaluation unit (14) detects the foreign body (11) by means of a variable that is dependent on the inductance of the at least one sensor coil (15).

Description

description

Charging system for galvanic charging of a

electrical energy storage of a vehicle, electrically powered vehicle, charging station for a vehicle and corresponding method

The invention relates to a charging system for the galvanically isolated charging of an electrical energy storage of an electrically driven vehicle with electrical energy, namely in particular an electrically driven motor vehicle, preferably a passenger car. The charging system comprises a vehicle-external primary unit with a primary coil for delivering electrical energy, as well as a vehicle-side secondary unit with a coupled to the energy storage secondary coil for receiving the energy. The invention also relates to an electrically driven vehicle, a charging station for such a vehicle, as well as a method for galvanically separate charging of an electrical energy storage of an electrically driven vehicle with electrical energy.

Electrically powered vehicles, in particular motor vehicles, are already state of the art. Such vehicles include an electric drive device - namely an electric drive motor - and are driven by means of the electric drive device. The electric drive device is supplied with electrical energy from an energy store, namely in particular from a so-called "traction battery." A particular challenge with electrically driven vehicles is that the energy store can be fully charged with electrical energy very quickly In the case of conventional charging systems, the user places the vehicle in the vicinity of a charging station ("charging station" or else a corresponding power connection) and connects it Vehicle via an electrical line with the charging station. The charging of the electrical energy storage takes place here in the conventional way via a cable. There are also more comfortable charging systems are known, which allow a wireless or galvanic separation of electrical energy. In this case, for example, the vehicle is parked above a ground unit (primary unit) such that a primary coil present in the primary unit is opposite a secondary coil arranged on the vehicle floor. The energy transfer now takes place with the aid of an alternating magnetic field between the primary unit of the charging station on the one hand and the secondary unit of the vehicle on the other hand. This is an inductive coupling between the primary coil and the secondary coil. It thus eliminates the manual connection of the vehicle to a charging station via appropriate lines. For the charging process, the user only needs to park the vehicle within a certain area above the primary unit and, if necessary, also to release the charging process.

In the present case, the interest is directed to the last-described more comfortable method, which allows wireless charging of the energy storage. The described convenient charging system can even enable an uncomplicated recharging of the vehicle in many places if corresponding primary units or ground units are installed. As a result, the disadvantage of the limited capacity of the energy storage can be compensated within certain limits: The vehicle can always be recharged, for example during the parking period. Also in public parking lots, parking bays and the like thus the installation of corresponding primary units in large numbers makes sense. However, if one were to equip such a large number of parking spaces and the like with corresponding primary units, one would have to contend with a new challenge: typically, not every parking space can be completed or monitored. As a result of conductive objects in the range of magnetic Alternating field hazards, such objects must be detected by appropriate measures and, where appropriate, the energy transfer can not be enabled or disabled. The presence of electrically conductive foreign bodies in the area of the alternating magnetic field entails the risk that this conductive object may heat up and, moreover, that the power electronics of the primary unit / secondary unit may be damaged. It is an object of the invention to provide a solution, as in a charging system of the type mentioned charging the energy storage can be done very effective and reliable. This object is achieved by a charging system, by an electrically powered vehicle, by a charging station and by a method having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description and the figures.

A charging system according to the invention is designed for electrically isolated charging of an electrical energy store of an electrically driven vehicle with electrical energy. The charging system includes a vehicle-external primary unit with a primary coil for discharging electrical energy, as well as a vehicle-side secondary unit with a coupled to the energy storage secondary coil for receiving the energy. According to the invention, at least one sensor coil arrangement is provided with at least one sensor coil for detecting an electrically conductive foreign object located in an energy transfer area between the primary unit and the secondary unit. In addition, the charging system also includes an electronic evaluation device, which is set up to detect the electrically conductive foreign body in the energy transmission area on the basis of a variable dependent on the inductance and / or the quality of the at least one sensor coil. The invention thus goes the way, to detect an electrically conductive foreign body in the space between the primary unit on the one hand and the secondary unit on the other hand use a sensor coil arrangement with at least one sensor coil, by means of which the presence of the foreign body can be detected by inductive means. The invention is based on the finding that the planned off armor of a plurality of parking spaces with respective primary units for charging electric vehicles, the problem arises that it is not possible at all, each parking and thus each primary unit or each charging se ready to monitor. The invention further builds on the recognition that the gap between the Primärein- unit and the secondary unit must be monitored for the presence of elec trically conductive foreign bodies, because such foreign bodies could lead to a threat, such as for heating this foreign body or abe to a damage to the power electronics and the like. Another finding is that such foreign body detected by suitable sensors and, where appropriate, the energy transfer does not have to be released or even switched off and interrupted. First, the threat of manipulation attempts with the help of a permanent monitoring of parking or lockable boxes bypass. Conductive objects randomly located in the area of the power field could then be located by manual control. However, these measures argue against a widespread and frequently used charging procedure. In contrast, the invention allows an automated or automatic detection of an electrically conductive foreign body in the energy transmission area, so that after detection of this foreign body, the charging process may be interrupted or the start of the charging process can not be released at all. Ge compared to the infrared detectors proposed in the art, the invention also has the advantage that the sensor coil assembly basically in all conceivable conditions can be used successfully, while optical systems are less practical, because sensitive to dirt. The charging system according to the invention thus enables a reliable detection of foreign bodies, regardless of the prevailing conditions, in particular also independent of contamination of the primary unit / secondary unit. Overall, thus a particularly reliable and reliable charging of the energy storage is possible. With regard to the sensor coil arrangement, basically two different embodiments are initially provided: Firstly, the sensor coil arrangement can be a coil arrangement that is different from the primary coil and from the secondary coil. This means that the at least one sensor coil is a coil formed separately from the primary coil and separately from the secondary coil. On the other hand, however, it can also be provided that the sensor coil arrangement comprises the primary coil and / or the secondary coil or is formed by the primary coil and / or the secondary coil. Thus, the already existing coils (primary coil and / or secondary coil) can also serve as sensor coils for the detection of conductive objects in the region of the power field. In this case, for example, the electronic evaluation device can be inductively coupled to the primary coil and / or secondary coil.

Also with regard to the arrangement of the at least one sensor coil various embodiments are provided:

In one embodiment, it is provided that such a sensor coil arrangement is integrated with at least one sensor coil in the vehicle-external primary unit. Thus, conductive foreign bodies closer to the primary coil than the secondary coil can be detected. In addition, this embodiment has the advantage that the foreign body can thus be detected even when charging the energy storage of such a vehicle whose secondary unit has no corresponding sensor coil arrangement. Additionally or alternatively, it can also be provided that such a sensor coil arrangement is integrated with at least one sensor coil in the vehicle-internal secondary unit. Thus, in turn, conductive foreign bodies can be detected particularly reliably, which lie in the vehicle vertical direction or in the vertical direction closer to the vehicle floor than the primary unit.

It proves to be advantageous if respective sensor coil arrangements are each integrated with at least one sensor coil both in the primary unit and in the secondary unit. This has the advantage that conductive foreign bodies can be detected within the entire height range between the primary unit and the secondary unit without incorrectly detecting the vehicle floor itself or metal parts located in the lower area of the vehicle as foreign bodies. Namely, the mutual sensor coil assemblies may have such ranges in the vertical direction that overlap each other, but are individually less than a minimum possible distance between the primary unit and the secondary unit. Thus, the entire height range between the primary unit and the secondary unit is covered in the vertical direction and thus can be checked for the presence of foreign matter, wherein the metal parts of the motor vehicle outside the detection range of the primary-side sensor coil assembly and thus can not cause misdetection. In one embodiment, it is provided that the evaluation device is set up to check the energy transfer region for the presence of a foreign body before the start of a charging process and / or during the charging process. In particular, the energy transfer area between the primary unit and the secondary unit is continuously or continuously monitored by means of the evaluation device for the presence of a foreign body. This monitoring preferably begins before the initiation the charging process and preferably lasts at least until the completion of the charging process. Thus, the charging process is very safe. To bring the security to a maximum, the evaluation device can output a signal after detection of a foreign body in the energy transmission area, due to which a charging process is interrupted or the start of a charging process is prevented.

The at least one sensor coil is preferably a planar or planar sensor coil. Particularly preferably, the sensor coil arrangement comprises a multiplicity of such planar sensor coils which are arranged in a common plane, for example also on a common printed circuit board.

The sensor coil arrangement can thus be a planar arrangement of a plurality of coils which are dimensioned in such a way that conductive objects of a specific size can still be detected up to a certain distance (preferably smaller than a minimum distance between primary unit and secondary unit). The planar or planar configuration of the sensor coil arrangement provides, in particular, for a compact arrangement which, for example, can be easily integrated into the primary unit and / or secondary unit. A helical configuration of the sensor coils in a plane has, in addition to the mentioned advantage with respect to the flat and simple construction, also functional advantages, namely in particular with regard to the characterization of the magnetic field.

Preferably, the at least one sensor coil-in particular the multiplicity of sensor coils-is designed as a printed conductor structure on a flexible printed circuit board. The arrangement of the sensor coil assembly on a flexible printed circuit board has the advantage that the entire sensor coil assembly requires relatively little space and thus even in can integrate the secondary unit of the vehicle, in which, as we know, little space is available.

The flexible circuit board can be easily inserted into the housing of the primary unit and / or secondary unit. Due to the planar arrangement of the individual coils, a uniform coverage of the detection range is achieved. If there are special objects in the housing in the vicinity of a single coil, such as fastening screws, the influence of these special objects can be taken into account by means of a modified geometry in the coil in question. In the case of a two-dimensional arrangement of coils, therefore, the geometry of that coil in whose vicinity or in the field special objects (own conductive objects of the system) are located in or on the housing (such as fastening screws) can be modified in such a way that an identical or otherwise a similar behavior - in particular an equal field distribution - as in the other coils results. In a preferred embodiment, it is provided that the sensor coil arrangement has a range in the vertical direction which is greater than half the maximum possible distance between the primary unit and the secondary unit. This means that by means of the sensor coil arrangement, the conductive foreign bodies can be detected up to a distance which is greater than half the maximum possible distance between the primary unit and the secondary unit. It is thus achieved that all foreign bodies located in the vicinity of the sensor coil arrangement can be detected, that is to say those foreign bodies which lie in the relevant energy transmission area.

It also proves to be particularly advantageous if the range of the sensor coil arrangement in the vertical direction is smaller than a minimum possible distance between the primary unit and the secondary unit. Thus, in turn, it can be prevented that the metallic components of the driving soil to lead to a misdetection and thus to an unwanted interruption of the charging process.

The maximum possible or the minimum possible distance between the primary unit and the secondary unit is understood in particular to mean distances which result in an unladen motor vehicle on the one hand or a motor vehicle with maximum load on the other hand. For motor vehicle charging stations, such as passenger cars, the minimum and maximum distances between the primary unit and the secondary unit may be determined taking into account the respective heights of all motor vehicles on the market. If the charging station for motor vehicles - especially for passenger cars - set up, it can be provided that is used as the maximum distance of the maximum distance in all possible passenger cars. Accordingly, the minimum possible distance for all passenger cars can be used as the minimum distance. This is based on the fact that the height at which the vehicle floor is located is standardized for passenger cars and thus lies within a predetermined value range. As a result of this procedure, it is achieved that the respective detection areas overlap in all possible passenger cars without the vehicle floor itself leading to a misdetection. If the charging station, however, for other types of

Vehicles - such as trucks or cleaning vehicles - determined, so the determination of the maximum and minimum distance can be made taking into account the respective vehicle.

As already explained, respective sensor coil arrangements can also be integrated into both the primary unit and the secondary unit, namely in such a way that respective detection areas of the mutual sensor coil arrangements overlap in the vertical direction. Thus, the entire height range between the primary unit and the secondary unit is deducted with respect to the detection of foreign bodies. covers, and it also misdetections are prevented due to fixed vehicle parts.

The above-mentioned distance between the primary unit and the secondary unit essentially corresponds to the distance between the vehicle floor on the one hand and the floor of the charging station on the other. The secondary unit is in fact usually mounted on the vehicle floor or below the motor vehicle and thus also forms the vehicle floor itself.

Conductive objects in the area of the power field, ie in the energy transmission area, can therefore be detected by inductive charging by means of suitable coil systems or respective sensor coil arrangements. In order to be able to monitor the entire area between the primary unit and the secondary unit, but avoid false triggering by the vehicle floor or metal parts in the lower area of the vehicle, the installation of the presented sensor coil arrangements in this case is proposed here-as already explained. The detection range of the two coil systems

(So the maximum distance between the coil system and a conductive foreign body) can be sized according to the requirements. The range of each coil assembly is preferably slightly more than half the maximum distance between the primary unit and the secondary unit (at minimum load), but is clearly less than the minimum distance between the primary unit and the secondary unit (at maximum load). With inductive charging, vehicles with different loading and vehicle types with differing ground clearances on metallic foreign bodies in the energy transmission area can be monitored and therefore safely charged.

Depending on the load state, the detection ranges of the two sensor coil arrangements thus overlap only slightly (without loading) or somewhat further (medium or large load of the vehicle). The represented design of the two sensor coil arrangements thus always ensures that that an introduced, conductive object can be detected at any time and independently of the current loading of the vehicle - and in particular also independently of the respective vehicle model - but the vehicle floor or body parts in the lower area of the vehicle do not cause a false triggering of the system ,

In one embodiment, it is provided that the sensor coil arrangement is assigned at least one test coil, by means of which the proper functioning of the sensor coil arrangement can be checked. This check is carried out in particular by short-circuiting the test coil. The at least one test coil is preferably arranged above or below the sensor coil arrangement. If, for example, the test coil is short-circuited at predetermined times, in particular by the evaluation device, this should be determined by the evaluation device on the basis of the monitored variable, which is dependent on the inductance of the at least one sensor coil. Short-circuiting may e.g. by means of a relay in which a make contact shorts the relevant test coil. This self-test capability prevents additional manipulation, such as coupling a high-power "matching" oscillator signal to prevent detection of conductive objects in the area of the power field.

Preferably, the evaluation device has an oscillator for providing an oscillator signal whose frequency can be changed depending on the inductance of the at least one sensor coil. The evaluation device can then be set up to determine, on the basis of the frequency of the oscillator signal as a variable, whether or not an electrically conductive foreign body is located in the energy transmission region. If the sensor coil arrangement contains a plurality of sensor coils, each of the sensor coils or, optionally, any desired group - for example series connection - can be connected to the oscillator of the evaluation device from a plurality or even all of the coils. be sen. This means that each sensor coil can be assigned a separate oscillator or, alternatively, a group of sensor coils can be coupled to a common oscillator. The at least one sensor coil can serve as an inductor of an LC sine oscillator, wherein a basic circuit known from the relevant literature can be used as LC oscillator. The oscillation frequency of the oscillator-that is, the frequency of the oscillator signal-depends, inter alia, on the inductance of the at least one sensor coil. Their effective inductance in turn is influenced by conductive objects in their environment. Namely, the magnetic field of the coil induces currents into the conductive foreign body, and eddy currents are formed here, which in turn have a retroactive effect on the magnetic field of the sensor coil. Thus, the frequency of the oscillator signal also changes in the presence of conductive foreign bodies in the energy transfer region. With modern micro-controllers, it is then possible to determine the current frequency of the oscillator signal without much effort and with high accuracy. Now, if a certain range of values for just allowable frequency deviations set, so can be detected with this arrangement, the introduction of conductive objects in the energy transmission area. As a monitored variable, additional or alternatively further properties of the sensor coil arrangement can be defined, such as a coil quality and / or a phase shift between the current and the voltage at the at least one sensor coil and / or an output amplitude of the oscillator signal.

With regard to the arrangement of the evaluation device, different embodiments are also provided: In particular, the evaluation device is integrated into that unit-primary unit or secondary unit-into which the sensor coil arrangement is also integrated. If two such sensor coil arrangements are used, namely one in the primary unit and one in the secondary unit, so too two separate electronic evaluation devices are used, namely an evaluation in the primary unit, and a separate evaluation in the secondary unit.

The evaluation device can also be arranged on the common printed circuit board as the sensor coil arrangement, namely in particular on a flexible printed circuit board. Alternatively, however, it can also be provided that the evaluation device is arranged on a separate printed circuit board, that is to say on a different printed circuit board than the sensor coil arrangement. The evaluation device can then be coupled to the at least one sensor coil via suitable connection techniques-galvanically or else galvanically separated. For example, the evaluation device can be coupled to the at least one sensor coil by means of field coupling. By way of example, larger conductive areas on the flexible printed circuit board on the one hand and on the evaluation device on the other hand can oppose each other, so that they are capacitively coupled to one another. Another possibility for coupling would be opposing coils integrated into the respective circuit boards, in which case an inductive coupling is provided. In principle, all types of field coupling are conceivable: capacitive, inductive and / or electromagnetic.

In the present case, a vehicle is understood to mean in particular a motor vehicle, namely preferably a passenger car. However, the invention is not limited to a motor vehicle and can also be applied to other electrically powered vehicle types, such as self-propelled cleaning machines, especially for corporate buildings, baggage trolleys at airports, forklifts and the like. It is only crucial that the electrical energy storage of the vehicle is charged by inductive means via a transformer including a primary coil and a secondary coil. The invention also relates to an electrically driven vehicle, in particular a motor vehicle, which has an electric drive device for driving the vehicle, as well as an electrical energy storage, which provides electrical energy for the drive device. The vehicle also includes a secondary unit with a secondary coil, which can be inductively coupled to charge the energy store with electrical energy with a vehicle-external primary coil of a primary unit. In the vehicle is a, especially in the secondary unit integrated,

Sensor coil assembly provided with at least one sensor coil, which is used for detecting a located in a power transmission area between the primary unit and the secondary unit, electrically conductive foreign body. The vehicle also includes an electronic evaluation unit, which is also integrated, for example, in the secondary unit and which can detect the electrically conductive foreign body in the energy transmission range on the basis of a variable dependent on the inductance and / or the quality of the at least one sensor coil.

A charging station according to the invention for an electrically driven vehicle is designed for galvanically separate charging of an electrical energy store of the vehicle with electrical energy and comprises a primary unit including a primary coil, which for charging the energy storage with electrical energy with a vehicle-side secondary coil of a secondary unit of the vehicle can be inductively coupled. The charging station comprises a sensor coil arrangement, in particular integrated in the primary unit, with at least one sensor coil for detecting an electrically conductive foreign body located in an energy transfer area between the primary unit and the secondary unit. The charging station also includes an electronic evaluation device which is integrated in particular in the primary unit and which is designed to use one of the inductance and / or the quality of the at least one sensor. Sorspule dependent size to detect the electrically conductive foreign body in the energy transfer area.

The invention also includes a method for the galvanically isolated charging of an electrical energy store of an electrically driven vehicle with electrical energy by discharging electrical energy through a vehicle-external primary coil of a primary unit, as well as by receiving the energy through a coupled to the energy storage vehicle-side secondary coil of a secondary unit of the vehicle. A electrically conductive foreign body located in an energy transfer area between the primary unit and the secondary unit is detected by means of a sensor coil arrangement having at least one sensor coil, wherein the electrically conductive foreign body in the energy transfer area by means of an electronic evaluation device coupled to the at least one sensor coil is detected by the inductance of the at least one sensor coil dependent size.

The preferred embodiments presented with reference to the charging system according to the invention and their advantages apply correspondingly to the vehicle according to the invention, to the method according to the invention and to the charging station according to the invention.

Further features of the invention will become apparent from the claims, the figures and the figures. All the features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or alone.

The invention will now be explained with reference to a preferred embodiment, as well as with reference to the accompanying drawings. It should be emphasized at this point that the embodiment described below represents only an exemplary embodiment of the invention and the invention is therefore not limited to this embodiment.

Show it:

1 shows a schematic representation of a side view of a charging system according to an embodiment of the invention;

Figures 2 to 4 in a schematic representation of the charging system according to FIG 1, wherein different positions of an electrically conductive foreign body are shown in a power transmission area;

5 to 7, the system according to FIG 1, wherein different

Distances between a primary unit and a secondary unit due to different loading states of a motor vehicle are shown;

8 shows a schematic representation of a plan view of a sensor coil arrangement; and

9 shows a block diagram of an electronic evaluation device, which is coupled to the sensor coil arrangement.

A charging system 1 shown schematically in FIG. 1 serves to charge an energy storage device 2 of an electrically driven vehicle 3 with electrical energy. The vehicle 3 is for example a motor vehicle, for example a passenger car. With electrical energy from the energy storage device 2 while an electric drive device 4 is supplied, which is designed for driving the vehicle 3. The drive device 4 is thus a electric drive motor, by means of which the wheels of the vehicle 3 are driven.

The energy storage 2 is a vehicle battery, which can supply not only the drive device 4 but also other components in the vehicle 3. The energy storage 2 is charged wirelessly with electrical energy. For this purpose, the energy storage device 2 is electrically connected to a secondary unit 5 of the vehicle 3. This secondary unit 5 is arranged in the floor area of the vehicle 3, for example below the floor or integrated in the vehicle floor. The arrangement of the secondary unit 5 in the front region of the vehicle 3 is shown merely by way of example; the secondary unit 5 can also be located in the middle region or else in the rear region of the vehicle 3, for example-viewed in the longitudinal direction of the vehicle 3.

The secondary unit 5 can, for example, have a housing in which the components belonging to the secondary unit 5 can be accommodated. These components include, in particular, a secondary coil, by means of which the energy store 2 can be charged with electrical energy by transformation. This secondary coil is electrically connected to the energy storage 2. This coil can be, for example, a planar coil whose windings are all in one plane, wherein this coil can be arranged on a printed circuit board. In the exemplary embodiment, the entire secondary unit 5 is designed flat, so that its extent in the vehicle longitudinal direction and vehicle transverse direction is significantly greater than the extension in the vehicle vertical direction. In the secondary unit 5, other components may be integrated, such as a rectifier and the like. Below the vehicle 3 is a charging station 6, which may be integrated, for example, in a parking lot, a parking bay or other parking opportunity. The charging station 6 includes a primary unit 7 which is mounted on a nem substrate or floor 8 rests and / or is integrated in the bottom 8. The primary unit 7 is also flat and extends in the horizontal direction. It includes a primary coil, which is not shown in greater detail in the figures, and which can be inductively coupled to said secondary coil of the vehicle 3, as a result of which electrical energy can be transmitted from the primary coil to the secondary coil and thus into the energy store 2. The primary coil may also be a planar or planar coil which is arranged on a printed circuit board and whose windings all lie in one plane.

For charging the energy storage device 2, the vehicle 3 is placed over the charging station 6, namely such that the secondary unit 5 is in vertical overlap with the primary unit 7 and thus lies above the primary unit 7. For this purpose, already known from the prior art centering and alignment units can be used. The charging process is then controlled by means of an electronic control device 9 of the charging station 6, which is indicated only schematically in FIG. To charge the energy store 2 with electrical energy, the primary coil is driven in such a way that a magnetic alternating field is generated between the primary coil and the secondary coil arranged parallel thereto. This field then induces an electrical voltage on the secondary coil and electrical current flows in the secondary circuit. From this AC voltage, a DC voltage is then generated with the aid of a rectifier, with which the energy storage 2 is charged.

The magnetic field is located in an intermediate region between the primary coil or primary unit 7 on the one hand and the secondary unit 5 on the other hand. This intermediate region is referred to below as the energy transfer region 10. This is because the transmission of electrical energy takes place in this area. In Figure 1, a distance in the vertical direction between the primary unit 7 and the secondary unit 5 is also denoted by d. Now, the interest is directed to the detection of an electrically conductive foreign body 11 in the energy transmission area 10. FIGS. 2 to 4 each show an enlarged view of the charging system 1 or the front area of the vehicle 3 (without the wheel). In the example according to FIG. 2, an electrically conductive foreign body 11 rests on the primary unit 7. This foreign body 11 poses a risk that it may heat up when transmitting the electrical energy and, moreover, that the electronic components of the charging system 1 may be damaged. This foreign body 11 is dangerous even if it is located at a distance to both the primary unit 7 and the secondary unit 5, as shown in FIG. Here lies between the foreign body 11 and the primary unit 7 additionally an electrically non-conductive spacer 12. From a conductive object in the field of power field is also a threat from when the foreign body 11 directly below or directly to the secondary unit 5 under the Vehicle 3 is located. This is shown by way of example in FIG. Here, a spacer is also located between the foreign body 11 and the secondary unit 7

12th

In order to be able to detect such a foreign body from an electrically conductive material, a sensor coil arrangement is respectively formed in one of the units 5, 7 or even both in the primary unit 7 and in the secondary unit 5

13 (FIG 8) with an associated electronic evaluation unit 14 (FIG 9) integrated. Referring now to FIG. 8, the sensor coil assembly 13 may include a plurality of planar sensor coils 15, all of which lie in a plane and are disposed on a, for example, flexible circuit board 16. The sensor coil assembly 13 thus represents a coil array, which is used to detect metallic Foreign bodies in the energy transmission area 10 is used. The planar sensor coil arrangement 13 is integrated in the respective unit (primary unit 7 or secondary unit 5) in such a way that the circuit board 16 extends in the horizontal direction and thus lies parallel to the primary coil and secondary coil. The sensor coil arrangement 13 can be arranged, for example, below or above the respective power coil. Optionally, the sensor coil assembly 13 may even comprise or be formed by the primary coil and / or secondary coil. The individual sensor coils 15 are also connected to terminals 17 on the circuit board 16, which are arranged on a tab 18 of the circuit board 16. Via these connections 17, sensor coils 15 can be connected to the electronic evaluation device 14.

It can now be provided that for each sensor coil 15 each such evaluation device 14 is provided. But it can also be provided that a subset of sensor coils 15 or even all sensor coils 15 are connected to a common evaluation device 14, as shown in FIG. The following is a possible functional principle outlined for evaluation: The sensor coil 15 serves as an inductance of an LC Sinusos zillators 19, which outputs an oscillator signal 20 whose frequency depends on the inductance of the sensor coil 15. The oscillation frequency of the oscillator 19 is therefore dependent inter alia on the inductance of the sensor coil 15. This inductance in turn is influenced by the conductive foreign body 11 in the energy transmission area 10. Namely, the magnetic field of the sensor coil 15 induces currents in the conductive foreign body 11, and eddy currents are generated here, which in turn have a retroactive effect on the magnetic field of the sensor coil 15. Thus, the frequency of the oscillator signal 20 also changes in the presence of a foreign body 11 in the energy transmission area 10. The oscillator signal 20 is then supplied to a threshold value switch 21, which then triggers a microcontroller 22. Recognize the Microcontroller 22 that a foreign body 11 is present in the energy transfer area 10, so gives the microcontroller

22 a logic or digital signal 23 from. This signal

23 is for example to the control device 9 of the charging system 1 and / or to a corresponding control unit of

Vehicle 3 is discharged, so that the charging process is interrupted or not started at all.

The respective sensor coil assemblies 13 of the primary unit 7 and the secondary unit 5 are arranged and configured such that they collectively cover an area which comprises the entire energy transfer area 10 or the entire magnetic field of the primary coil. Thus, foreign objects 11 can be detected at any point in the energy transfer area 10. Referring now to FIGS. 5 to 7, the respective detection ranges of the mutual sensor coil arrangements 13 are explained in greater detail. As already explained, a sensor coil arrangement 13 is integrated into the secondary unit 5 and a corresponding sensor coil arrangement 13 into the primary unit 7. The sensor coil arrangement 13 integrated into the secondary unit 5 has a detection area

24 (sloping hatching in FIGS. 5 to 7), while the sensor coil arrangement 13 integrated into the primary unit 7 likewise has a corresponding detection area 25 (increasing hatching in FIGS. 5 to 7). The charging system 1 is designed so that the two detection areas 24, 25 overlap even at a maximum possible distance d _max in the vertical direction. This maximum possible distance d _max between the primary unit 7 and the secondary unit 5 is shown in FIG. 5 and adjusts itself with a minimum load of the vehicle 3. In contrast, a minimum possible distance d _m i _n between the primary unit 7 and the secondary unit 5 is shown in FIG 7, in which case the loading of the vehicle 3 is maximum. Even at the minimum distance d _m i _n , the primary unit 7 is outside the range or the detection range 24 of the vehicle-mounted sensor coil arrangement 13. The secondary unit 5 is also located outside the range or range. In other words, the respective sensor coil arrangements 13 are arranged and designed so that their respective ranges are greater than half the maximum distance d _max , but smaller than the minimum distance d _m i _n . Thus, it is achieved that, on the one hand, the complete energy transmission area 10 is covered, but on the other hand, the metallic components of the vehicle floor are not mistakenly interpreted as foreign bodies. These lie lely borrowed outside the detection range of the bottom sensor coil assembly 13th

If the charging station 6 for motor vehicles - especially for passenger cars - set up, it can be provided that the maximum distance d _max the maximum possible distance is used in all possible passenger cars. Accordingly, the minimum possible distance for all passenger cars can be used as the minimum distance d _m i _n . This is based on the fact that the height at which the vehicle floor is located is standardized for passenger cars and thus lies within a predetermined value range. By this procedure it is achieved that in all possible passenger cars, the respective detection areas 24, 25 overlap, without the vehicle floor itself leading to a misdetection.

If the charging station 6 for other types of vehicles - such as trucks or cleaning vehicles - set up, so the determination of the maximum and minimum distance d _max d _m i _n taking into account the respective vehicle type.

In FIG. 6, a distance di is shown as it is set for a mean load of the vehicle 3.

In the primary unit 7 and / or the secondary unit 5, at least one test coil (not shown in the figures) may be integrated, by means of which the proper Operation of the at least one sensor coil assembly 13 can be checked. For this purpose, the at least one test coil can be short-circuited by means of an electrical switch at predetermined times, whereby the inductance of the sensor coils 15 is also influenced, which should be determined by the evaluation device 14. This Selbsttestmöglichkeit prevents additional manipulation, such as by coupling an external oscillator signal with high power.

Claims

claims

1. charging system (1) for electrically isolated charging of an electrical energy store (2) of an electrically driven vehicle (3) with electrical energy, comprising:

- a vehicle-external primary unit (7) with a primary coil for delivering electrical energy, and

a vehicle-side secondary unit (5) with a secondary coil coupled to the energy store (2) for receiving the energy,

marked by

at least one sensor coil arrangement (13) with at least one sensor coil (15) for detecting an electrically conductive foreign body (11) located in an energy transfer area (10) between the primary unit (7) and the secondary unit (5)

- An electronic evaluation device (14) which is adapted to detect on the basis of one of the inductance of the at least one sensor coil (15) dependent size of the electrically conductive foreign body (11) in the energy transfer area (10).

2. charging system (1) according to claim 1, characterized in that a said sensor coil arrangement (13) in the primary unit (7) is integrated.

3. charging system (1) according to claim 1 or 2, characterized in that a said sensor coil arrangement (13) in the secondary unit (5) is integrated.

4. charging system (1) according to any one of the preceding claims, characterized in that the evaluation device (14) is adapted to before the start of a charging process and / or during the charging process the Energieübertragungsbe- (10) for the presence of a foreign body (11 ).

5. charging system (1) according to any one of the preceding claims, characterized in that the evaluation device (14) is adapted to after detection of a foreign body (11) in the energy transmission region (10) output a signal (23) due to a Charging interrupted or the start of a charging process is prevented.

6. charging system (1) according to any one of the preceding claims, characterized in that the sensor coil arrangement (13) has a plurality of planar sensor coils (15) which are arranged in a common plane.

7. charging system (1) according to one of the preceding claims, characterized in that the at least one sensor coil (15) is designed as a conductor track structure on a flexible printed circuit board (16).

8. charging system (1) according to any one of the preceding claims, characterized in that the sensor coil assembly (13) in the vertical direction has a range which is greater than half of a maximum possible distance (d _max ) between the primary unit (7) and the secondary unit (5).

9. charging system (1) according to any one of the preceding claims, characterized in that the sensor coil assembly (13) in the vertical direction has a range which is smaller than a minimum possible distance (d _m i _n ) between the primary unit (7) and the secondary unit (5).

10. charging system (1) according to any one of the preceding claims, characterized in that respective sensor coil assemblies (13) in both the primary unit (7) and in the secondary unit (5) are integrated and respective detection ranges (24, 25) of overlap on both sides of sensor coil assemblies (13).

11. charging system (1) according to any one of the preceding claims, characterized in that the sensor coil assembly (13) is associated with at least one test coil, by means of which, in particular by shorting the test coil, the proper operation of the sensor coil assembly (13) can be checked.

12. Charging system (1) according to one of the preceding claims, characterized in that the evaluation device (14) has an oscillator (19) for providing an oscillator signal (20) whose frequency depends on the inductance of the at least one sensor coil (15). is variable, wherein the evaluation device (14) is adapted to determine on the basis of the frequency of the oscillator signal (20) as a size, whether or not an electrically conductive foreign body (11) in the energy transmission region (10).

13. Electrically powered vehicle (3), in particular a motor vehicle, with an electric drive device (4) for driving the vehicle (3), with an electrical energy store (2) for providing electrical energy for the drive device (4), and with a secondary unit (5) with a secondary coil which can be inductively coupled to charge electrical energy with a primary coil (7) external of the vehicle to charge the energy store (2),

marked by

- A, in particular in the secondary unit (5) integrated, sensor coil arrangement (13) with at least one sensor coil (15) for detecting a in an energy transfer area (10) between the primary unit (7) and the secondary unit (5) located, electrically conductive foreign body ( 11) and

14. charging station (6) for an electrically driven vehicle (3), for electrically isolated charging of an electrical energy storage device (2) of the vehicle (3) with electrical energy, comprising a primary unit (7) including a

Primary coil, which can be coupled inductively to charge the energy store (2) with electrical energy with a vehicle-side secondary coil of a secondary unit (5),

marked by

- A, in particular in the primary unit (7) integrated, sensor coil assembly (13) with at least one sensor coil (15) for detecting a in an energy transfer area (10) between the primary unit (7) and the secondary unit (5) located, electrically conductive foreign body ( 11) and

- An electronic evaluation device (14) which is adapted to detect on the basis of one of the inductance of the at least one sensor coil (15) dependent size of the electrically conductive foreign body (11) in the energy transmission range (10).

15. A method for galvanically isolated charging of an electrical energy storage device (2) of an electrically driven vehicle (3) with electrical energy, comprising the steps of: - delivering electrical energy through a vehicle-external primary coil of a primary unit (7) and

Receiving the energy by means of a vehicle-side secondary coil of a secondary unit (5) of the vehicle (3) coupled to the energy store (2),

marked by

Detecting an electrically conductive foreign body (11) located in an energy transmission region (10) between the primary unit (7) and the secondary unit (5) by means of a sensor coil arrangement (13) having at least one sensor coil (15),

- wherein the electrically conductive foreign body (11) in the energy transmission region (10) by means of an at least one sensor coil (15) coupled electronic Aus¬ Value device (14) is detected based on a dependent of the inductance of the at least one sensor coil (15) size.