SE538341C2

SE538341C2 - Device, method and system for enabling secure wireless transfer of energy to a vehicle

Info

Publication number: SE538341C2
Application number: SE1451089A
Authority: SE
Inventors: André Claesson; Kenneth Lindgren
Original assignee: Scania Cv Ab
Priority date: 2014-09-17
Filing date: 2014-09-17
Publication date: 2016-05-24
Also published as: DE102015011211A1; SE1451089A1

Abstract

23 Abstract A device and a method for enabling secure wireless transfer of energy from acharging station in a roadway to a vehicle, wherein the device includes a pluralityof sensors configured to generate a detection field in a certain pattern underneaththe vehicle for sensing a metallic object, and a control unit, wherein the controlunit is configured to: provide authentication data of an authentication between thevehicle and the charging station; determine a distance d between the chargingstation and the vehicle, and compare the distance with a threshold distance dt;generate activation data to the plurality of sensors in order to activate thedetection field when the distance between the vehicle and the charging station isequal to or less than the threshold distance dt and before any transfer of energy isstarted; monitor if any metallic object is in the detection field; generate controldata for controlling transfer of energy from the charging station to the vehicle independence of the monitoring and the authentication data. (Figure 2)

Description

Device, method and system for enabling secure wireless transfer of energy to a vehicle Field of the invention The present invention relates to a device, a method and a system for enablingsecure wireless transfer of energy from a charging station in a roadway to avehicle. The present invention also relates to a computer program, a computer program product and a vehicle comprising the device.

Background of the invention An electric vehicle is a vehicle with an energy storage that can be charged withelectricity, and the electricity stored in the energy storage drives or contributes todrive the wheels of the vehicle. One kind of electric vehicle is a so called “plug-in”electric vehicle that can be charged from an external source of energy such as a wall socket.

Charging from a wall socket normally means that the vehicle has to remainstationary for several hours. This may work for private cars which are used only afew hours a day, but is not suitable for busses or trucks that should be under wayfor a larger part of the day and/or night. For such vehicles inductive charging viacharging stations in the roadway is an alternative, where a large amount of energyin a short time may be transferred to the vehicle when the vehicle is passing thecharging station or shortly stops at the charging station e.g. at a bus stop. Whencharging, a large amount of energy is wirelessly transferred from the chargingstation to the vehicle and care has to be taken such that the energy transfer canbe made in a secure way. Especially objects containing metal are hazardous as they may become very hot if exposed to the inductive energy field. ln US2011074346 a wireless vehicle charger safety system is described. Athermal sensor is used to detect high temperatures in the energy transfer area. ltis brieﬂy mentioned that a metal detector may be used to detect any metal parts.When an object is detected the energy transfer is stopped or limited. Further, in 2 US2012/0181875, a stationary unit is described which has a device for detectingthe presence of an electrically conductive object in an area for inductive transferof electric energy. Measuring coils cover the transfer area to sense any electrically conductive object in the area.

The above-mentioned systems concern charging a vehicle at a stationarycharging station, where the energy transfer is made over a rather large period oftime. When larger amounts of energy are to be transferred, e.g. when thecharging station is embedded in the roadway and the vehicle shall be charged in ashort time, more care has to be taken to ensure that no metallic objects are nearthe charging zone.

Summary of the invention lt is thus an object of the invention to alleviate at least some of the drawbacks withthe prior art. lt is a further object of the invention to achieve a device and amethod that enables secure wireless transfer of energy from a charging station in a roadway to a vehicle. lt is a still further object to be able to detect metallic objects that come underneaththe vehicle before or during charging. lt may be possible to charge the vehicleduring a longer period of time, because it is possible to have control of the spaceunderneath the vehicle before and during charging and there is less need for a security margin.

The device includes a plurality of sensors configured to generate a detection fieldin a certain pattern underneath the vehicle for sensing a metallic object. Thedevice further includes a control unit. The control unit is configured to: - provide authentication data of an authentication between the vehicle and thecharging station; - determine a distance d between the charging station and the vehicle, andcompare the distance with a threshold distance dt; 3 - generate activation data to the plurality of sensors in order to activate thedetection field when the distance between the vehicle and the charging station isequal to or less than the threshold distance dt and before any transfer of energy isstarted; - monitor if any metallic object is in the detection field; - generate control data for controlling transfer of energy from the charging stationto the vehicle in dependence of the monitoring and the authentication data.

According to one embodiment, the control unit is configured to generate activationdata to activate the detection field only if the authentication data reveals that thevehicle is positively authenticated to be charged from the charging station.

According to one embodiment, the threshold distance d1 is equal to the length of avehicle, or a set length of at least the length of the vehicle.

According to one embodiment, the plurality of sensors includes inductive sensors and/or capacitive sensors.

According to one embodiment, the detection field is configured to have a shape ofa fence when generated.

According to one embodiment, the vehicle is equipped with a receiver unitconfigured to receive energy from the charging area, and wherein the detectionfield is configured to have a shape of a fence that at least partly encircles the receiver unit.

According to one embodiment, the detection field is configured to have a width wand to extend at least partly around the circumference of the vehicle.

According to one embodiment, the detection field is configured to have a height hextending between at least one of the plurality of sensors and a roadway of thevehicle.

According to one embodiment, the control unit is configured to generate controldata allowing transfer of energy to the vehicle if at least one charging condition isfulfilled.

According to one embodiment, the charging conditions includes: authenticationdata that reveals that the vehicle is positively authenticated to be charged fromthe charging station; the vehicle is within a certain distance from the chargingstation; an activated detection field.

According to one embodiment, the control unit is configured to generate controldata preventing transfer of energy to the vehicle from the charging station if anymetallic object is detected in the detection field.

According to one embodiment, the control unit is configured to generate anotification signal to the driver and/or a central unit if any metallic object isdetected in the detection field.

The method for enabling secure wireless transfer of energy from a chargingstation in a roadway to a vehicle, wherein the vehicle is equipped with a pluralityof sensors configured to generate a detection field in a certain pattern underneaththe vehicle for sensing a metallic object, comprises: - performing an authentication between the vehicle and the charging station; - activating the detection field when a distance d between the vehicle and thecharging station is equal to or less than a threshold distance dt and before anytransfer of energy is started; - monitoring if any metallic object is in the detection field; - controlling transfer of energy from the charging station to the vehicle in dependence of the monitoring and the authentication.

According to one embodiment, the method comprises activating the detection fieldonly if the vehicle is positively authenticated to be charged from the chargingstation.

According to one embodiment, the method comprises transferring energy to thevehicle if at least one charging condition is fulfilled.

According to one embodiment, the charging conditions includes: a positiveauthentication of the vehicle to be charged from the charging station; the vehicleis within a certain distance from the charging station; and the detection field isactivated.

According to one embodiment, the method comprises preventing transfer ofenergy to the vehicle from the charging station if any metallic object is detected bythe detection field.

According to one embodiment, the method comprises notifying the driver and/or acentral unit if any metallic object is detected by the detection field.

According to a further aspect, the invention relates to a computer program P,wherein the computer program P includes a computer program code to cause acontrol unit, or a computer connected to the control unit, to perform the methodaccording to any of the steps herein.

According to a still further aspect, the invention relates to a computer programproduct comprising a computer program code stored on a non-transitorycomputer-readable medium to perform the method steps according to any of thesteps as disclosed herein, when the computer program code is executed by a control unit or by a computer connected to the control unit. 6 According to another aspect, the invention relates to a system comprising thedevice and a charging station configured for wireless transfer of energy from thecharging station to the vehicle.

According to one embodiment, the vehicle includes a distance detector configuredto measure a distance between the vehicle and the charging station.

According to one embodiment, the vehicle and the charging station are configured to communicate with each other in a wireless way.

According to still another aspect, the invention relates to a vehicle comprising the device according to any of the embodiments as described herein.

Preferred embodiments are described in the dependent claims and in the detaileddescription.

Short description of the appended drawinqs Below the invention will be described with reference to the accompanying figures,of which: Fig. 1 shows an electric vehicle with a receiver area for wireless transfer of energyfrom a charging station embedded in the roadway according to one embodiment.Fig. 2 shows the electric vehicle and charging station in Fig. 1 seen from aboveaccording to one embodiment.

Fig. 3 illustrates a control unit according to one embodiment of the invention.

Fig. 4A illustrates a side view of a part of the electric vehicle of Fig. 1 and 2, andthe height h of the detection field according to one embodiment.

Fig. 4B illustrates a view from above of a part of the electric vehicle of Fig. 1 and2, and the width w of the detection field according to one embodiment.

Fig. 5 illustrates a flow chart of a method of the invention according to one embodiment.

Detailed description of preferred embodiments of the invention 7 ln Fig. 1 an electric vehicle 1 travelling on a roadway 5 is illustrated. The travellingdirection is illustrated by the arrow 14. The electric vehicle 1, hereafter called thevehicle 1, may be any kind of vehicle arranged to be electrically charged in awireless way. For example, the vehicle 1 may be a private car, a truck, a lorry, abus or any other kind of industrial or working vehicle. The vehicle 1 has a pluralityof wheels 2. The vehicle 1 is further equipped with a receiver unit 3 for receivingenergy in a wireless way. The receiver unit 3, also called a “pick up”, is located inthe bottom part of the vehicle 1. A charging station 6 for wireless transfer ofenergy is also shown embedded in the roadway 5. The charging station 6 maytransfer energy to the receiver unit 3 when certain conditions have been fulfilled.The receiver unit 3 may be configured to be lowered to facilitate charging from thecharging station 6. When no charging is in progress, the receiver unit 3 may beraised again to protect the receiver unit 3.

The vehicle 1 and the charging station 6 may be arranged to communicate in awireless way, as illustrated with bent arrows in the figure. The vehicle 1 and thecharging station 6 may be arranged to communicate directly with each other. Onekind of such wireless communication is referred to as vehicle-to-vehiclecommunication (V2V). The vehicle 1 and the charging station 6 may also bearranged to communicate with each other via an external computer 8, server, roadside unit or similar. One kind of such wireless communication is referred to asvehicle-to-infrastructure communication (V2l). The wireless communication mayalso be conducted via mobile communication servers, via an application in acommunication unit or via a server. The vehicle 1 is for the purpose of wirelesscommunication equipped with a unit for wireless communication 4. The chargingstation 6 is for the purpose of wireless communication also equipped with a unit for wireless communication 7.

The receiver unit 3 may include a charging plate (not shown) to receive theenergy from the charging station 6. The charging plate may be an inductiveenergy charging plate, thus capable of receiving energy via induction. Thereceived energy is then transferred to a battery arrangement (not shown) of the 8 vehicle 1 for charging the vehicle 1, either directly or via an energy managementunit (not shown) of the vehicle 1. The energy management unit may include e.g.an AC/DC-rectifier (not shown) to convert the energy to a suitable format for thebattery arrangement and the vehicle 1. The charging station 6 may include acharging plate (not shown) connected to a power supply (not shown). Thecharging station 6 may also include a control unit 25 that is configured to startenergy transfer from the charging station 6, stop energy transfer from the chargingstation 6, and/or regulate the effect of the energy transfer from the chargingstation 6. The charging station 6 and the vehicle 1 may exchange data forauthentication via the units for wireless communication 4, 7 such that a correctamount of energy can be transferred. ln Fig. 2 a view from above of the vehicle 1, the road way 5 and the chargingstation 6 is shown. The vehicle 1 is here arranged with a device 19 for enablingsecure wireless transfer of energy from the charging station 6 in the roadway 5 tothe vehicle 1. A system may include the device 19 and the charging station 6. Thedevice 19 includes a plurality of sensors 9. The sensors 9 are configured togenerate a detection field in a certain pattern underneath the vehicle 1 for sensinga metallic object. When a metallic object is sensed, the sensor 9 detecting theobject sends detection data to the control unit 10. The control unit 10 may thusknow an approximate position of the detected metallic object. The sensors 9 maybe inductive sensors and/or capacitive sensors. Thus, the plurality of sensors 9may according to one embodiment only comprise inductive sensors. According toanother embodiment, the plurality of sensors 9 may only comprise capacitivesensors. According to another embodiment, the plurality of sensors 9 includes amix of inductive sensors and capacitive sensors. The sensors 9 are connected toand energized via an electrical system of the vehicle 1 (not shown). The sensors 9thus act as metal detectors.

The device 19 further includes a control unit 10. The control unit 10 is furtherillustrated in Fig. 3, and includes a processing unit 15 and a memory unit 16. Theprocessing unit 15 may be made up of one or more Central Processing Units 9 (CPU). The memory unit 16 may be made up of one or more memory units. Amemory unit may include a volatile and/or a non-volatile memory, such as a flashmemory or Random Access Memory (RAM). The control unit 10 further includes acomputer program P including a computer program code to cause the control unit10, or a computer connected to the control unit 10, to perform any of the methodsteps that will be described in the following. The control unit 10 may be anElectronic Control Unit (ECU).

The control unit 10 is configured to provide authentication data of anauthentication between the vehicle 1 and the charging station 6. Theauthentication means that the vehicle 1, charging station 6 and/or the externalcomputer 8 performs an authentication procedure, where data of the vehiclecharging needs, identification data e.t.c. of the vehicle 1 may be “hand shaken”with the charging station 6. Thus, it may be identified if the vehicle 1 is an electricvehicle that is in need for charging, if the charging station 6 is compatible with thereceiving unit 3 for transfer of energy between the charging station 6 and thereceiving unit, how much energy that should be transferred and/or during howlong time the energy should be transferred etc. Various parameters such as thevelocity of the vehicle 1 may aid in authentication procedure. The velocity of thevehicle 1 may also be transmitted to the charging station 6 such that the chargingstation 6 may prepare charging of the vehicle 1. From the authenticationprocedure authentication data is retrieved. The authentication data may e.g.include data describing that the vehicle 1 is positively authenticated to be chargedfrom the charging station 6. This means that the charging station 6 may chargethe vehicle 1. The authentication data may instead include data describing thatthe vehicle 1 is negatively authenticated to be charged from the charging station6. This means that the charging station 6 cannot or will not charge the vehicle 1.The authentication procedure may start when the vehicle 1 is at a certain distancefrom the charging station 6. The distance between the vehicle 1 and the charging station 6 may be determined and monitored as indicated below.

The control unit 10 is further configured to determine a distance d between thecharging station 6 and the vehicle 1. The control unit 10 is configured to comparethe distance with a threshold distance dt. The threshold distance dt is according toone embodiment equal to the length of the vehicle 1, or a set length of at least thelength of the vehicle 1. The length of the vehicle 1 may be a known parameter tothe control unit 10. The distance d may be determined based on data of theposition of the vehicle 1 and the position of the charging station 6, and bycalculating the relative distance between the vehicle 1 and the charging station 6by using their positions, respectively. The detection field should be activated atleast a length of the vehicle 1 before the charging station 6 to search for metallicobjects in the area where the vehicle 1 will drive over before charging.

The position of the vehicle 1 may be determined with a positioning unit 20 in thevehicle 1. The positioning unit 20 is arranged to determine the position of thevehicle 1, and may be configured to receive signals from a global positioningsystem such as GNSS (Global Navigation Satellite System), for example GPS(Global Positioning System), GLONASS, Galileo or Compass. Alternatively thepositioning unit 20 may be configured to receive signals from for example one orseveral distance detectors in the vehicle 1 that measure relative distances to forexample a road side unit, nearby vehicles or similar with a known position. Basedon the relative distance or distances the positioning unit 20 may determine theposition of the own vehicle 1. A detector may also be configured to detect asignature in for example a road side unit, whereby the signature represents acertain position. The positioning unit 20 may then be configured to determine itsown position via detection of the signature. The positioning unit 20 may instead beconfigured to determine the signal strength in one or a plurality of signals from abase station or road side unit with known position, and thereby determine theposition of the vehicle 1 by using triangulation. Of course may some of abovementioned technologies be combined to ensure a correct position determination ofthe vehicle 1. The positioning unit 20 is configured to generate a position signalwith the position of the vehicle 1, and to send it to the control unit 10. ll The position of the charging station 6 may be a known position to the chargingstation 6, the external computer 8 and/or the vehicle 1 (and thereby known to the control unit 10).

The vehicle 1 may also be equipped with one or several distance detectors 11configured to measure a distance between the vehicle 1 and a certain point ormark 21 on the charging station 6, located for example on an outer edge of thecharging station 6 facing the traffic in the lane. The distance sensor 11 may e.g.include a camera unit, a radar unit or a laser unit. The distance detector 11 mayalso include performing some kind of identification of the charging station 6, e.g.that the certain point or mark 21 is identified. The distance detector 11 isconfigured to generate a distance signal with the distance d between the vehicle 1and the charging station 6, and to send it to the control unit 10.

The control unit 10 is further configured to generate activation data to the pluralityof sensors 9 in order to activate the detection field when the distance between thevehicle 1 and the charging station 6 is equal to or less than the threshold distancedt and before any transfer of energy is started. The control unit 10 thus monitorsthe distance between the vehicle 1 and the charging station 6. When the sensors9 are activated by the activation data, the detection field is turned on and thesensors 9 starts to detect if any metallic objects are within the field. As previouslyexplained, the sensors 9 may be inductive, capacitive or a mix of inductive orcapacitive. ln any case, will a metallic object in the detection field cause adisturbance in the field that is detected by the sensors 9, and sent as detectiondata to the control unit 10. The control unit 10 monitors the detection data fromthe sensors 10, and determines if a metallic object has been detected or not. Thedetection data may also include data of the specific sensor or sensors 9 thatdetected the metallic object. Then the position of any detected object may be determined by the control unit 10.

The control unit 10 is further configured to generate control data for contro||ingtransfer of energy from the charging station 6 to the vehicle 1 in dependence of 12 the monitoring and the authentication data. According to one embodiment, thecontrol unit 10 is configured to generate control data allowing transfer of energy tothe vehicle 1 if at least one charging condition is fulfilled. The charging conditionsmay include: authentication data that reveals that the vehicle 1 is positivelyauthenticated to be charged from the charging station 6; the vehicle 1 is within acertain distance from the charging station 6; an activated detection field.

Thus, if a metallic object is detected, no transfer of energy is allowed at thischarging station 6. The control unit 10 may observe any disturbance in thedetection data, and determine that a metallic object is underneath the vehicle 1.The control unit may thus be configured to generate control data preventingtransfer of energy to the vehicle from the charging station if any metallic object isdetected in the detection field. Thus, an ongoing transfer of energy may beinterrupted, or a planned transfer of energy never started. The control data mayaccording to one embodiment be sent wirelessly to the charging station 6 in orderto interrupt any ongoing or planned transfer of energy. lf no metallic object isdetected, the transfer of energy may be allowed. Further, the authenticationprocess has to give authentication data that allows the vehicle 1 to be charged bythe charging station 6. Othervvise no charging may be allowed.

The device 19 may comprise further detectors 12A, 12B, 13 that are arranged onthe vehicle 1 at certain positions, e.g. at a front end of the receiving unit 3 (12A),at a rear end of the receiving unit 3 (12B) and/or at the rear end of the vehicle 1(13). These detectors 12A, 12B, 13 may be detectors that are configured to sensethe position of the mark 21 that points out the position of the charging station 6.The detectors 12A, 12B, 13 may include a camera unit, a laser unit or a radar unitto identify the mark 21. When any of the detectors 11, 12A, 12B, 13 is aligned orin any other sense is positioned in relation to the mark 21, an event may betriggered. For example, the charging may start when the detector 12A at the frontend of the receiving unit 3 and the mark 21 are aligned, and stop when thedetector12B at the rear end of the receiving unit 3 and the mark 21 are aligned,or when the detector 13 at the rear end of the vehicle 1 and the mark 21 are 13 aligned. The detection field may be de-activated when the detector 12B at the rearend of the receiving unit 3 and the mark 21 are aligned, or when the detector 13 atthe rear end of the vehicle 1 and the mark 21are aligned. The mark 21 may bearranged with a detector 24 in the charging station 6 to control transfer of energy.The detector 24 may be the same kind of detector as the previously mentioneddetectors, and may be configured to sense the position of any of the detectors12A, 12B, 13 or other marking to indicate the position of the detectors 12A, 12B,13, and to give data to the charging station 6 in order to activate or deactivateenergy transfer from the charging station 6. The device 19 may send data to thecharging station 6 via wireless communication to control the charging, and/or thecharging station 6 may send data to control the charging via wireless communication. lf a metallic object is detected by the detection field, a notification may be sent tothe driver of the vehicle 1 and/or to a central unit (not shown) to inform that thereis a metallic object on the roadway 5. The control unit 10 may thus be configuredto generate a notification signal with a notification to the driver and/or a centralunit if any metallic object is detected in the detection field. The notification signalmay be sent wirelessly from the vehicle 1 to the central unit. The notification mayinclude information of the size of the object and/or the position of the object. Theposition of the object may be approximated to the position of the vehicle 1. Thenotification may be notified to the driver via an indicating unit 23 in the vehicle 1,e.g. via a screen on the dashboard, a load speaker or similar. The notification maythus be visual, audial or tactile.

According to one embodiment, the control unit 10 is configured to generateactivation data to activate the detection field only if the authentication data revealsthat the vehicle 1 is positively authenticated to be charged from the chargingstation 6. Thus, if the authentication data describes that the vehicle 1 is notallowed to be charged by the charging station 6, the detection field is not activatedas no monitoring of metallic objects has to be made. 14 The detection field is according to one embodiment configured to have a shape ofa fence when generated. The sensors 9 are distributed on the underside 26 of thechassis and/or body of the vehicle 1. The sensors 9 are arranged to send out thedetection field such that it gets a certain pattern. The detection field is accordingto one embodiment configured to have a shape of a fence that at least partlyencircles the receiver unit 3. Thus, the sensors 9 are configured to send out sucha detection field. The detection field is according to one embodiment configured tocompletely, to a greater extent or at least partly extend around the circumferenceof the vehicle 1. As illustrated in figure 2, the sensors 9 illustrated as triangles aredistributed at the bottom sides of the vehicle 1, and along the bottom front andbottom rear part of the vehicle 1. The sensors 9 may also send out a detectionfield that covers an area inside the wheels 2 of the vehicle 1. The sensors 9 maythen be distributed also along the bottom side of the vehicle 1 closest to the innerside of the wheels 2. One sensor 9 may transmit a detection field covering awhole side of the vehicle 1 underneath the vehicle 1. lnstead a plurality of sensors9 may transmit a detection field covering a whole side of the vehicle 1 underneaththe vehicle 1. ln Fig. 4A a side view of the space underneath the vehicle 1 is shown, and in Fig.4B the space is illustrated from above. Sensors 9 are located facing down fromthe vehicle 1 to the roadway 5. When the sensors 9 are active, they will generatea detection field bordering the bottom side 17 of the vehicle 1 and the roadway 5.As illustrated in the figures, the detection field generated by the sensors 9 has aheight h and a width w. Fig. 4B, the width w of the detection field extends from theouter side 18 of the vehicle 1 and towards the center of the vehicle 1. The width wmay according to one embodiment be from some millimeters up to 0.5 m. Theheight h extends between the bottom side 17 of the vehicle 1 and the roadway 5of the vehicle 1. The sensors 9 are here located aligned with the bottom side 17 ofthe vehicle 1, and the height h thus extends from the bottom side 17 of the vehicle1 to the roadway 5. The space between the receiver unit 3 and the roadway 5 ishowever not covered to any extent by the detection field.

The detection field thus creates a fence of detection underneath the vehicle 1encircling the receiver unit 3 to monitor if the vehicle 1 gets a metallic object underthe vehicle 1 when driving over an object, or if any metallic object is thrown intothe space between the bottom part 17 (Fig. 4A) of the vehicle 1 and the road wayof the vehicle 1.

The detection field may be calibrated for different positions of the wheels 2 of thevehicle 1, as the wheels 2 of the vehicle 1 may come into the detection field andotherwise erroneously trigger detection of a metallic object. lf the control unit 10knows how the wheels 2 disturb the detection field, the detection of the wheels 2in the field may be neglected in the detection data. For example, the detectionfield may be calibrated for different wheel positions, such that the wheels do notdisturb the detection of any metallic object. The detection field may also becalibrated for different steering angles etc., in which steering angles the wheels 2will come into the detection field to different extent. The detection field may e.g. be calibrated in the factory when manufacturing the vehicle 1.

The device 19 may also retrieve data from other sensors or detectors in thevehicle 1, such as a detector 22 configured to detect large objects, especially non-metallic objects, which may damage the receiver unit 3, in the driving direction ofthe vehicle 1. lf a large object is detected, the receiver unit 3 may be raised, andno charging may be performed. The driver and/or central station may be sent anotification of the large object and the position of the object.

The vehicle 1 communicates internally between its units, devices, sensors,detectors etc. via a communication bus, for example a CAN-bus (Controller AreaNetwork) which uses a message based protocol. Examples of othercommunication protocols that may be used are TTP (Time-Triggered Protocol),Flexray, etc. ln that way signals and data described herein may be exchangedbetween different units, devices, sensors and/or detectors in the vehicle 1. Signalsand data may instead be transferred wirelessly between the different units,devices, sensors and/or detectors. 16 The invention also relates to a method, which will now be described withreference to the flowchart in Fig. 5. The method may be implemented as programcode and saved in the memory unit 16 in the control unit 10 (Fig. 3). The methodmay thus be implemented with the above described hardware of the device 19(Fig. 2) in the vehicle 1. The method comprises performing an authenticationbetween the vehicle 1 and the charging station 6 (A1). As previously described,the authentication may be initiated when the vehicle 1 is a certain distance, orwithin a certain distance from the charging station 6. The authentication is madewith an authentication process which may give authentication data that describesif the vehicle 1 can and/or will be allowed to be charged from the charging station6 or not. The authentication may include transfer of wireless data between thevehicle 1, the charging station 6 and/or the external computer unit 8 (Fig. 1). Forexample, when the charging station 6 has been detected by the device 19, or viceversa, a request may be sent from the vehicle 1 to the charging station 6 forcharging. Data about the vehicle 1, such as amount of energy needed, length ofthe vehicle 1, velocity, type of vehicle 1 etc. may be sent to the charging station 6.The charging station 6 may evaluate the received data and determine if thevehicle 1 may be charged, and data of the charging such as duration of thecharging and how much energy that should be transferred. An acknowledgementmay then be sent to the vehicle 1 from the charging station 6 with the result of theevaluation. This authorization process may instead be made by the control unit 10 or in the external computer unit 8.

The method also includes activating the detection field when the distance dbetween the vehicle 1 and the charging station 6 is equal to or less than athreshold distance dt and before any transfer of energy is started (A2). Thedistance d between the vehicle 1 and the charging station 6 is thus monitored.The detection field may only be activated if the vehicle 1 is positivelyauthenticated to be charged with energy from the charging station 6. lt is furthermonitored if any metallic object is in the detection field (A3), and transfer of 17 energy from the charging station 6 to the vehicle 1 is controlled in dependence ofthe monitoring and the authentication (A4).

According to one embodiment, the method comprises allowing transfer of energyto the vehicle 1 if at least one charging condition is fulfilled. The chargingconditions may include: a positive authentication of the vehicle 1 to be chargedfrom the charging station 6; the vehicle 1 is within a certain distance from the charging station 6; and the detection field is activated.

The present invention is not limited to the above-described preferredembodiments. Various alternatives, modifications and equivalents may be used.Therefore, the above embodiments should not be taken as limiting the scope ofthe invention, which is defined by the appending claims.

Claims

18 Claims

1. A device (19) for enabling secure wireless transfer of energy from acharging station (6) in a roadway (5) to a vehicle (1 ), wherein the device (19)includes a plurality of sensors (9) configured to generate a detection field in acertain pattern underneath the vehicle (1) for sensing a metallic object, and acontrol unit (10), wherein the control unit (10) is configured to: - provide authentication data of an authentication between the vehicle (1) and thecharging station (6); - determine a distance d between the charging station (6) and the vehicle (1 ), andcompare the distance with a threshold distance dt; - generate activation data to the plurality of sensors (9) in order to activate thedetection field when the distance between the vehicle (1) and the charging station(6) is equal to or less than the threshold distance dt and before any transfer ofenergy is started; - monitor if any metallic object is in the detection field; - generate control data for controlling transfer of energy from the charging station(6) to the vehicle (1) in dependence of the monitoring and the authentication data.

2. The device (19) according to claim 1, wherein the control unit (10) isconfigured to generate activation data to activate the detection field only if theauthentication data reveals that the vehicle (1) is positively authenticated to becharged from the charging station (6).

3. The device (19) according to claim 1 or 2, wherein the thresholddistance d1 is equal to the length of a vehicle (1 ), or a set length of at least thelength of the vehicle (1 ).

4. The device (19) according to any of the preceding claims, wherein the plurality of sensors (9) includes inductive sensors and/or capacitive sensors.

5. The device (19) according to any of the preceding claims, wherein thedetection field is configured to have a shape of a fence when generated. 19

6. The device (19) according to claim 5, wherein the vehicle (1) isequipped with a receiver unit (3) configured to receive energy from the chargingarea (6), and wherein the detection field is configured to have a shape of a fence that at least partly encircles the receiver unit (3).

7. The device (19) according to claim 6, wherein the detection field isconfigured to have a width w and to extend at least partly around thecircumference of the vehicle (1 ).

8. The device (19) according to claim 6 or 7, wherein the detection fieldis configured to have a height h extending between at least one of the plurality of sensors (9) and a roadway (5) of the vehicle (1 ).

9. The device (19) according to any of the preceding claims, wherein thecontrol unit (10) is configured to generate control data allowing transfer of energyto the vehicle (1) if at least one charging condition is fulfilled.

10. The device (19) according to claim 9, wherein the charging conditionsincludes: authentication data that reveals that the vehicle (1) is positivelyauthenticated to be charged from the charging station (6); the vehicle (1) is withina certain distance from the charging station (6); an activated detection field.

11. The device (19) according to any of the preceding claims, wherein thecontrol unit (10) is configured to generate control data preventing transfer ofenergy to the vehicle (1) from the charging station (6) if any metallic object isdetected in the detection field.

12. The device (19) according to any of the preceding claims, wherein thecontrol unit (10) is configured to generate a notification signal to the driver and/ora central unit if any metallic object is detected in the detection field.

13. Method for enabling secure wireless transfer of energy from acharging station (6) in a roadway (5) to a vehicle (1 ), wherein the vehicle (1) isequipped with a plurality of sensors (9) configured to generate a detection field ina certain pattern underneath the vehicle (1) for sensing a metallic object, themethod comprising: - performing an authentication between the vehicle (1) and the charging station(6): - activating the detection field when a distance d between the vehicle (1) and thecharging station (6) is equal to or less than a threshold distance dt and before anytransfer of energy is started; - monitoring if any metallic object is in the detection field; - controlling transfer of energy from the charging station (6) to the vehicle (1) independence of the monitoring and the authentication.

14. The method according to claim 13, comprising activating thedetection field only if the vehicle (1) is positively authenticated to be charged fromthe charging station (6).

15. The method according to claim 13 or 14, wherein the thresholddistance d1 is equal to the length of a vehicle (1 ), or a set length of at least the length of the vehicle (1 ).

16. The method according to any of the claims 13 to 15, wherein theplurality of sensors (9) includes inductive sensors and/or capacitive sensors.

17. The method according to any of the claims 13 to 16, wherein thedetection field has a shape of a fence.

18. The method according to claim 17, wherein the vehicle (1) isequipped with a receiver unit (3) configured to receive energy from the chargingstation (6), and wherein the detection field in the shape of a fence at least partly encircles the receiver unit (3). 21

19. The method according to claim 18, wherein the detection field has a width w and extends at least partly around the circumference of the vehicle (1 ).

20. The method according to claim 18 or 19, wherein the detection fieldhas a height h extending between at least one of the plurality of sensors (9) and the roadway (5) of the vehicle (1 ).

21. The method according to any of the claims 13 to 20, comprising transferring energy to the vehicle (1) if at least one charging condition is fulfilled.

22. The method according to claim 21, wherein the charging conditionsincludes: a positive authentication of the vehicle (1) to be charged from thecharging station (6); the vehicle (1) is within a certain distance from the chargingstation (6); and the detection field is activated.

23. The method according to any of the claims 13 to 22, comprisingpreventing transfer of energy to the vehicle (1) if any metallic object is detected inthe detection field.

24. The method according to any of the claims 13 to 23, comprisingnotifying the driver and/or a central unit if any metallic object is detected in thedetection field.

25. A computer program P, wherein said computer program P includes acomputer program code to cause a control unit (10), or a computer connected tosaid control unit (10), to perform the method steps according to any of claims 13-24.

26. A computer program product comprising a computer program codestored on a non-transitory computer-readable medium to perform the methodsteps according to any of the claims 13-24, when said computer program code is 22 executed by a control unit (10) or by a computer connected to said control unit(10).

27. A system comprising the device (19) according to any of the claims 1to 10 and a charging station (6) configured for wireless transfer of energy from thecharging station (6) to the vehicle (1).

28. The system according to claim 27, wherein the vehicle (1) includes adistance detector (11) configured to measure a distance between the vehicle (1)and the charging station (6).

29. The system according to claim 27 or 28, wherein the vehicle (1) andthe charging station (6) are configured to communicate with in each other in a wireless way.

30. A vehicle (1) comprising a device (19) according to any of the claims1 to 12.