FR2971898A1 - Energy transmitting device for use in motor vehicle to wirelessly charge battery of mobile phone, has electromagnetic unit moving and positioning primary coil in preset position under secondary coil for energy transmission by induction - Google Patents

Abstract

The transmitting device has a movable primary coil (27) to be placed under a secondary coil of a receiving device to perform energy transmission by induction. An electromagnetic unit moves and positions the primary coil in a predetermined position. The unit has a magnet (43) surrounding the primary coil, and two pairs of electromagnets (39a, 39b, 41a, 41b) respectively placed on both sides of two directional axes. The electromagnets generate a magnetic field of same polarity as that of the magnet. The primary coil has a surface that is in contact with an inner wall of a housing (25). An independent claim is also included for a method for aligning a primary coil of a transmitting device with a secondary coil of a receiving device to transmit energy by induction.

Description

The invention relates to the field of vehicle dashboards, for example motor vehicles, and relates to wireless charging systems for electrical equipment. BACKGROUND OF THE INVENTION More specifically, it relates to equipment and methods for wireless charging of mobile open-ended electrical appliances.

Wireless charging equipment is conventionally composed of two parts: a transmitter device and a receiver device. The transmitter and receiver devices are each equipped with a coil respectively called primary and secondary coil. In view of being recharged, a mobile device (for example a mobile phone) is equipped with a receiver device and is placed on a base equipped with a transmitting device. The primary and secondary coils are electrically isolated from one another, but intended to be magnetically coupled. To do this, they must be placed close to each other and aligned one above the other. The primary coil (or emitter) is traversed by an electric current that will generate a magnetic field. This magnetic field is captured by the secondary coil (or receiver) which will convert it into electricity. The induced electric current generated in the secondary coil is used to recharge the battery of the mobile device. The transmission of energy is therefore by induction.

One of the main problems encountered in the implementation of this technology is the alignment of the primary and secondary coils, since the amount of magnetic field received by the secondary coil - and thus the equipment performance - is dependent on the recovery rate between the two coils. Nowadays, there is a demand for the realization of versatile wireless charging stations. In versatile bases, the transmitting devices must be able to adapt to all kinds of mobile devices regardless of their shape and size and therefore the location of their receiving device. In addition, there is a demand for equipment allowing free placement of the mobile device on the base without the user needs to align himself the primary and secondary coils. In other words, equipment is sought where coil alignment is automatic. Finally, there is a demand for wireless charging equipment that can be used in a motor vehicle where the mobile device, placed on the base, is likely to move during its charging period. It is therefore sought equipment for which the movement of the receiver device on the transmitter device does not affect or little induction energy transmission.

Concerning the problem of optimizing the alignment of the primary and secondary coils, one of the solutions provided by the prior art, in particular by the document US2010264871, is illustrated in FIG. 1. This document discloses a charging equipment (1 ) wireless for which the primary coil (3) (or emitter) is placed free in the housing (5) of a base (7). The primary coil (3) can move and slide to position itself in front of the secondary coil (9) (or receiver) of a mobile device (11) placed on the surface (13) of the base (7). The displacement and the alignment of the primary coil (3) results from the cooperation between magnets (15, 17) placed respectively at the center of each of the coils (3, 9). However this solution is not entirely satisfactory for an application in a vehicle. Indeed, if the device (11) to be reloaded is moved on the surface (13) of the base (7), for example if the driver negotiates a turn too quickly, the magnets (15, 17) are not powerful enough to get back into place and the mobile device (11) is no longer supported. In addition, the implementation of this solution implies that a magnet (17) is present in the center of the secondary coil (9) which is not always the case. This solution lacks versatility.

Regarding the free placement of the mobile device on the base, there are equipment whose transmitter device has several coils forming a mesh. When the mobile device is placed on the charging base, its secondary coil is then necessarily above one of the primary coils of said base. It does not matter then where the mobile device is placed and if it moves on the base or not, it is always in position to be loaded. This solution, however, has the disadvantage of being very expensive. In addition, it does not allow perfect alignment of the coils so that the secondary coil will almost never cover the entire coil. In addition to being expensive, such a solution therefore has a low yield.

Going further, the document EP2043226 discloses equipment whose emitter device has a coil made mobile and able to align itself under a secondary coil. When a mobile device is placed on the base, the primary coil is moved in a predetermined scanning pattern to locate the secondary coil and align itself beneath it to effect power transmission. The displacement of the primary coil is in the plane of the housing of the base by mechanical means, for example by means of motorized axes. The transmitting device is further capable of locating a displacement of the receiving device and of readjusting the position of the primary coil if necessary. Such a solution is therefore suitable for use in vehicles but is relatively expensive because it requires the introduction of a complex apparatus and motorized to move the primary coil. The object of the invention is to solve the problems posed by the prior art while at the same time offering the person skilled in the art a new system for recharging wireless electric apparatus with a less costly voice coil.

To this end, the subject of the invention is a transmitter device for wireless charging equipment of an electrical apparatus, said device comprising a mobile primary coil intended to be placed under the secondary coil of a receiver device in order to perform a transmission of energy by induction, remarkable in that it further comprises electromagnetic means configured to move the primary coil and / or position it in a predetermined position.

Preferably, the electromagnetic means of displacement and / or positioning comprise at least one magnet surrounding the primary coil. According to one embodiment of the invention, the electromagnetic means are configured to move and / or position the primary coil along a direction axis and comprise at least one pair of electromagnets disposed facing each other and on both sides of the said axis of direction. According to a preferred embodiment of the invention, the electromagnetic means are configured to move and / or position the primary coil according to two non-parallel axes forming a plane and comprise at least two pairs of electromagnets arranged so that at each axis of direction is associated at least one pair of electromagnets so that the primary coil can be moved and / or positioned in all points of said plane, and in that the electromagnets of each pair are arranged facing each other and on both sides of the direction axis they are associated with. Advantageously, the electromagnets are configured to generate a magnetic field of the same polarity as that of the magnet surrounding the primary coil so as to repel it.

According to a preferred embodiment of the invention, the emitter device further comprises a housing having a sealed housing filled with dielectric fluid and the primary coil is confined in said housing.

Alternatively or additionally, it comprises a housing having a housing in which the primary coil is confined and at least one of the inner walls of said housing and / or at least one of the faces of the primary coil in contact with each other , has a coating comprising polytetrafluoroethylene, preferably when the primary coil has a shield on its lower surface said coating is applied on said shield. According to an exemplary embodiment, it further comprises a charging system, the primary coil is connected to said charging system by means of a flexible electronic sheet, and the electronic sheet has inside the housing a length at least equal to the largest diagonal presented by said housing. Preferably, said recharging system further comprises a control module to which the electromagnets of electromagnetic displacement and / or positioning means are electrically connected, and said control module is configured to control the displacement and / or positioning of the primary coil in the housing by changing the power of at least one of said electromagnets. Advantageously, the control module further comprises measuring means for detecting the possible presence of a secondary coil placed close to said primary coil and / or for determining their recovery rate. For example, the control module is configured to analyze the result of the measurements made by the measuring means, to compare them with reference measurements and to control the displacement and / or positioning of the primary coil as a function of the result of the measurement. these measures. Preferably, the control module is configured to actuate alternately the measuring means and the electromagnetic means of displacement and / or positioning. Optionally, the charging system is configured so that the measuring means remains actuated during the inductive energy transmission step. The invention also relates to a vehicle which is remarkable in that it comprises an emitter device as defined above.

Finally, the subject of the invention is a method of aligning the primary coil of an emitter device as defined above with the secondary coil of a receiver device with a view to a remarkable induction energy transmission comprising least the following steps: - detection of the possible presence of secondary coil and / or determination of the rate of recovery of said secondary coil by the primary coil by measuring the characteristics presented by the primary coil and comparison of the result of the measurements made with measurements of reference; Moving the primary coil to align it under the secondary coil depending on the result of these measurements; remarkable in that the displacement step uses electromagnetic means of displacement and / or positioning of the primary coil, and in that preferably the measurement and displacement steps are performed alternately.

Optionally, the method is initiated by detecting the presence of an object on an interface surface of said receiving device.

It will be understood from reading the definition that has just been given that the implementation of the invention consists in using an electromagnetic field to move the primary coil to align it under the secondary coil and / or to place it in a given position for measurements. The invention consists in surrounding the primary coil of a magnet and using at least one electromagnet to act on this magnet by pushing it under the action of a magnetic field of the same polarity and thus move the coil. Preferably, the invention uses two pairs of electromagnets, placed along two non-parallel axes of displacement of the primary coil defining a plane. Preferably the electromagnets are placed at the cardinal points of the plane in which the primary coil moves. The pair or pairs of electromagnets will generate magnetic fields of the same polarity as that of the magnet surrounding the coil which will have the effect of pushing it to a position of equilibrium between the different magnetic forces involved. The invention then consists in being able to modify the position of the coil, and thus to be able to move the primary coil, by modulating the power of at least one electromagnet. The invention proposes means for non-motorized displacement of a primary coil in the housing of a transmitting device.

The invention will be clearly understood and other aspects and advantages will become clear from reading the description which follows, given by way of example, with reference to the accompanying drawings in which: FIG. 1 is a representation of FIG. a wireless charging system according to the prior art; FIG. 2 is a first schematic representation of a transmitter device according to the invention illustrating the means of confinement of the coil allowing it to move freely; - Figure 3 is another schematic representation of a transmitter device according to the invention illustrating the electromagnetic displacement means of the coil.

FIG. 1 having already been commented on in the introductory part, reference will now be made to FIG. 2 presenting a transmitting device (19) according to the invention for wireless charging equipment of an electrical appliance or more precisely for the charging base or sending base of such equipment. The transmitter device (19) is a near-field system capable of transmitting energy by induction. It comprises a housing (21) having a flat surface, called interface surface (23), on which a receiving device (not shown) is intended to come to rest. The housing (21) has, under this interface surface (23), a housing (25) in which a primary coil (27), or transmitting coil, can be displaced in at least one direction axis and preferably in two axes. direction defining a plan. The plane in which the primary coil (27) moves is parallel to the interface surface (23) and of the same shape and dimensions. The primary coil (27) is confined in the housing (25) of the housing (21) of the transmitter device (19). Optionally, the primary coil (27) has a magnet disposed at its center.

The primary coil (27) preferably has, in known manner, a shield (29) whose function is to limit the application of the magnetic field in the direction opposite to that of the interface surface (23). The shield (29) is then, in our example, disposed on the underside of the coil (27), and conventionally has a diameter slightly greater than that of the coil (27).

According to the invention, the primary coil (27) is connected to a flexible electronic sheet (31) which makes it possible to connect it to a charging system (31). The electronic web (29) is placed slice upwards to give it good flexibility. So that the primary coil (27) can be positioned at any point of the plane formed of the housing (25), the electronic web (29) advantageously has a length inside said housing (25) at least equal to the largest diagonal presented by said housing (25). It will be noted that the primary coil (27) moves only according to the length and the width of the housing (25) in which it is confined. The dimensions of said housing (25) do not allow its displacement in height. Preferably, the primary coil (27) has a freedom of movement of less than one millimeter on this axis. The dimensions in length or in width of the housing (25) and the housing (21) are not limiting of the invention.

So that the primary coil (27) can move in the housing (25) without the risk of being damaged by a phenomenon of wear due to friction on the inner surface of said housing (25) several solutions are possible by the man of the job.

In a first embodiment of the invention, the housing (21) is a sealed housing comprising a dielectric fluid (35), for example an electrically insulating liquid or an oil. The dielectric fluid (35) will serve to provide mobility and lubrication of the primary coil (27) in the housing (25). The housing (21) then has a seal (37) at the inlet of the electronic web (31) in the housing (25). It is also conceivable in another embodiment of the invention (not shown) to use air as a dielectric fluid and to promote the mobility of the coil in the housing by the addition of a layer of polytetrafluoroethylene or PTFE (marketed for example under the trade mark Teflon®) on the inner wall or walls of the housing intended to come into contact with the primary coil or its shielding. Complementarily or alternatively, the coil and / or its shield also have a PTFE coating on the face or faces intended to come into contact with the inner walls of the housing. It is recalled for all intents and purposes that PTFE is a polymer known for its good thermal and chemical resistance properties, as well as for the extremely low coefficient of friction that it has. Moreover, PTFE shows in known manner a high dielectric strength.

Remarkably, the transmitter device (19) according to the invention comprises electromagnetic means for moving the primary coil (27) in the housing (21) in order to place it under a secondary coil whose presence and position will have been detected. as we will see. When the primary coil (27) is confined in a housing (21) allowing its movement by electromagnetic means only according to its length, the emitter device (19) will then have two electromagnets (39a, 39b). These electromagnets (39a, 39b) are arranged facing one another and placed on either side of said housing (21) at its transverse edges, preferably outside the housing (21). . The implementation of a single pair of electromagnets (39a, 39b) is for example, when the respective dimensions of the primary coil (27) and the housing (25) allow displacement only along a single axis of direction , or when other means for moving the primary coil (27) are provided for the other axis of direction.

However, with the aim of promoting the versatility of the transmitting device (19) and as illustrated in FIG. 3, the skilled person will benefit from the fact that the respective dimensions of the primary coil (27) and its housing (25) allow movement along two axes of direction forming a plane. The invention then preferably uses at least two pairs of electromagnets (39, 41). Advantageously, the four electromagnets (39a, 39b, 41a, 41b) constituting the pairs (39, 41) are placed at the four cardinal points of the plane in which the primary coil (27) moves. Each steering axis is associated with a pair of electromagnets (39, 41).

The primary coil (27) is itself surrounded by at least one magnet (43) that can be positively or negatively charged. If several magnets surround the primary coil (27) they have the same polar orientation. The pairs of electromagnets (39, 41) will generate a magnetic field of the same positive or negative polarity as that of the magnet (43) surrounding the primary coil (27) which will have the effect of repelling it. The primary coil (27) is placed at a given position between the two magnets of a pair (39, 41) according to the power presented by each of them. This position corresponds to a position of equilibrium between the different magnetic forces involved. When the two electromagnets of a pair (39, 41) are of the same power, the primary coil (27) is placed equidistant from the two electromagnets ( 39a, 39b, or 41a, 41b).

This position is advantageously a central position in one of the directions of the plane formed by the inner lower wall of the housing (25). When only one of the electromagnets (39a, 41a or 39b, 41b) of a pair is magnetized, the primary coil (27) is displaced until it sticks against the wall of the slot of the housing (25) behind which there is other electromagnet of the pair (39b, 41b or 39a, 41a), not magnetized. It is well understood how by modulating the respective power of the two electromagnets (39a, 39b, or 41a, 41b), it is possible to determine a given position on the axis separating the two electromagnets (39a, 39b, or 41a, 41b) and to place the primary coil (27).

When the transmitter device (19) has at least four electromagnets (39a, 39b, 41a, 41b) arranged in pairs along the four slices of a four-sided case, it is possible to place the primary coil (27) at any point the plane formed by the lower wall of the housing (25). The invention is remarkable in that it makes it possible to define the coordinates of a position of the primary coil (27) inside the housing (25) and to move it there. The determination of a given position and the modulation of the power of the electromagnets (39a, 39b, 41a, 41b) is provided by a control module (43) presented by a transmission unit (45) of the charging system (33). ).

Preferably, once the primary coil (27) placed under the secondary coil, the electromagnets (39a, 39b, 41a, 41b) are demagnetized. The primary coil (27) remains in place and is supplied with electricity by a power module (47) of the charging system (33) via the electronic web (31) so as to perform the energy transmission by induction.

It will be understood that the transmitter device (19) according to the invention must allow the free positioning of the receiver device (not shown) on the interface surface (23) of the base, that is to say that it The user is not asked to proceed with the alignment of the coils. Therefore, according to a preferred embodiment of the invention, the emitting device (19) also has means for detecting an object deposited on its surface, measurement means for detecting the relative position of the object. two coils and / or the determination of their recovery rate.

The means for detecting an object on the interface surface (23) of the housing (21) of a transmitter device (19) are known to those skilled in the art and will not be detailed herein. It will be noted for the sake of clarity that it is possible, for example, to envisage means implementing the detection of a capacitance change of an electrode placed on or near the interface surface (23). ) in response to the removal of an object on said surface. In this way, when an object is detected on the interface surface (23), the information is transmitted to the control module (43) which will initiate the method of aligning the primary coil (27) with the coil secondary, and to this end put in motion the primary coil (27) to go in search of a possible secondary coil to which it is intended to couple.

Preferably, this setting in motion is done in a first time according to a predefined scanning scheme consisting of a set of determined positions of the primary coil (27) in the plane of the housing (25) for which measurements are made in order to the detection of a secondary coil in the vicinity. The transmitter device (19) therefore advantageously has means for detecting the relative position of two coils. Such detection means are known to those skilled in the art and for example described in document EP2043226. These means implement for example the monitoring of the modification of the inductance presented by the primary coil (27) when approaching the secondary coil. Indeed, the inductance of the primary coil (27) will increase in the vicinity of an object having magnetic properties such as a secondary coil. The result of these measurements is transmitted to the control module (43). The presence of the secondary coil is detected by the control module (43) following the increase of the inductance of the primary coil (27) beyond a first predetermined threshold value. The control module (43) then controls the displacement of the primary coil (27) according to a second scanning scheme which aims to promote this increase in inductance until it reaches or exceeds a second predetermined threshold value indicative of a suitable alignment. or enough of the two coils for a transfer of energy in a yield considered to be acceptable. The control module (43) will thus define a recovery rate of the two coils. According to the invention, the displacement of the primary coil (27) and the inductance measurements made for the detection of the secondary coil and the alignment of the two coils are successively and alternately. Thus, in a first step, the coil will for example be moved by the electromagnets (39a, 39b, 41a, 41b) to a first predetermined position by a detection pattern of the detection of the secondary coil. During the duration of this movement the detecting means are inactive. In a second step, the electromagnets (39a, 39b, 41a, 41b) are demagnetized and the control module (43) will activate the detection means to make a first measurement of the inductance of the primary coil (27).

If the result of the measurement does not allow the control module (43) to conclude that it is in the vicinity of a secondary coil, the control module (43) controls the movement of the primary coil (27) by the electromagnets ( 39a, 39b, 41a, 41b) to the second predetermined position of the detection scanning scheme. It will be recalled that the scanning scheme according to the invention is composed of a set of regularly spaced points whose spacing and location are chosen to test the entirety of the interface surface (23) in a minimum of measurements. . During all the phases of displacement the detecting means are inactive. If, in any of the positions of the scanning scheme, the measurements carried out do not lead to the conclusion of the presence of a secondary coil, the primary coil (27) is returned to its initial position and is not supplied with electricity with a view to a transmission of energy. Such a situation results for example from the removal of any object on the interface surface (23) by the user. It will be noted in passing that the detection of a secondary coil and not of a single object, such as for example coins or a keychain, deposited on the interface surface (23) allows the transmitter device to avoid applying a magnetic field to metal objects that would be heated, which could result in injury to the user.

If the result of the measurement allows the control module (43) to conclude that there is a secondary coil nearby. The control module (43) will move the primary coil (27) according to a new, finer scanning scheme for refining the alignment of the coils.

During the transmission of energy, the transmitter device (19) will advantageously measure continuously or regularly the recovery rate of the two coils. If this rate varies so as to pass below the threshold corresponding to a defined rate and considered as acceptable, the detection and positioning means of the primary coil (27) under the secondary coil are again activated for a repositioning of the primary coil ( 27). Such a situation occurs when, for example, the vehicle on which the transmitting device is embarked takes a sharp turn and the mobile device to be loaded is moved.

Preferably, the transmitting device (19) has known means for calculating the amount of energy to be transmitted and for preventing the user when the charging operation of the receiving device is completed. When the mobile device is removed from the base, the control unit (43) controls the repositioning of the primary coil (27) to its starting position. Communication between the primary coil (27) and the control module (43) is via the electronic web (31). The signal emitted by the primary coil (27) can advantageously be processed by a communication module (49) ensuring its demodulation before being transmitted to the control unit (43).

Advantageously, one or more LEDs (not shown) are connected to the primary coil (27) to allow the user to locate the primary coil (27) under the interface surface (23) and for example follow its displacement when this is guided by the control module (43) to search for the secondary coil. In such a case the housing (21) will advantageously have a translucent wall at its interface surface (23).

As we have seen, the invention has many advantages among which are: - the absence of mechanical means for implementing the movement of the primary coil (27). The latter is connected only to a flexible electronic web (31). Which reduces the production costs. the possibility of continuously optimizing the positioning of a transmitting coil (27) under a receiver coil in order to maintain a suitable efficiency of the transmission of energy throughout the charging operation, which enables it to be adapted for use in a motor vehicle where said device to be loaded is likely to move during its loading. - The versatility related to the freedom of positioning ("free positioning") that the transmitter device (19) according to the invention can adapt to different types of electrical devices regardless of their size or shape.

The invention is not limited to the embodiments described herein and given by way of example, but encompasses all variants conceivable by those skilled in the art within the scope of the definition that has been given. Thus it is possible to envisage transmitting devices whose housing shape allows the primary coil to reach all possible positions by being moved by an odd number (3, 5, 7 ...) of electromagnets.

Claims (16)

REVENDICATIONS1. Transmitting device (19) for wireless charging equipment of an electrical apparatus, said device (19) comprising a movable primary coil (27) intended to be placed under the secondary coil of a receiver device in order to carry out a transmission of induction energy, characterized in that it further comprises electromagnetic means configured to move the primary coil (27) and / or position it at a predetermined position. 2. transmitter device (19) according to claim 1 characterized in that the electromagnetic means of displacement and / or positioning comprise at least one magnet (43) surrounding the primary coil (27). Transmitting device (19) according to one of claims 1 or 2, characterized in that the electromagnetic means are configured to move and / or position the primary coil (27) along a direction axis and comprise at least one pair of electromagnets ( 39), the electromagnets (39a, 39b) being arranged opposite one another and on either side of said axis of direction. 4. Transmitting device according to one of claims 1 or 2 characterized in that the electromagnetic means are configured to move and / or position the primary coil (27) along two non-parallel axes forming a plane and comprise at least two pairs of electromagnets ( 39, 41) arranged so that at each axis of direction is associated at least one pair of electromagnets (39, 41) so that the coil can be moved and / or positioned in all points of said plane, and in that the electromagnets (39a, 39b, 41a, 41b) are arranged facing one another and on either side of the direction axis with which they are associated. 5. transmitter device (19) according to one of claims 3 to 4 characterized in that the electromagnets (39a, 39b, 41a, 41b) are configured to generate a magnetic field of the same polarity as that of the magnet (43) surrounding the coil primary (27) so as to repel it. 15 6. transmitter device (19) according to one of claims 1 to 5 characterized in that it further comprises a housing (21) having a housing (25) sealed filled with dielectric fluid (35) and that the primary coil ( 27) is confined in said housing (25). 7. transmitter device (19) according to one of claims 1 to 5 characterized in that it further comprises a housing (21) having a housing (25) wherein the primary coil (27) is confined and in that at least one of the inner walls of said housing (27) and / or at least one of the faces of the primary coil (27) in contact with each other, has a coating comprising polytetrafluoroethylene, preferably when the primary coil (27) has a shield (29) on its lower surface, said coating is applied to said shield (29). 8. transmitter device (19) according to one of claims 6 to 7 characterized in that it further comprises a charging system (33), the primary coil (27) being connected to said charging system (33) by means of an electronic web (31) flexible and in that the electronic web (31) has inside the housing (25) a length at least equal to the largest diagonal presented by said housing (25). 9. transmitter device (19) according to claim 8 characterized in that said recharging system (33) further comprises a control module (43) to which are electrically connected the electromagnets (39a, 39b, 41a, 41b) electromagnetic means for moving and / or positioning, and in that said control module (43) is configured to control the movement and / or positioning of the primary coil (27) in the housing by changing the power of at least one said electromagnets (39a, 39b, 41a, 41b). Transmitting device (19) according to claim 8 to 9, characterized in that the control module (43) further comprises measuring means for detecting the possible presence of a secondary coil placed close to said primary coil (27). ) and / or to determine their recovery rate. Transmitting device (19) according to claim 10, characterized in that the control module (43) is configured to analyze the result of the measurements made by the measuring means, to compare them with reference measurements and to control the displacement. and / or positioning the primary coil (27) according to the result of these measurements. 12. transmitter device (19) according to claim 11 characterized in that the control module (43) is configured to actuate alternately the measuring means and the electromagnetic means of displacement and / or positioning. 13. transmitter device (19) according to claim 12 characterized in that the charging system (33) is configured so that the measuring means remain actuated during the energy transmission step by induction. 14. Vehicle characterized in that it comprises a transmitter device (19) according to one of claims 1 to 13. 15. A method of aligning the primary coil (27) of a transmitter device (19) according to one of claims 1 to 13 with the secondary coil of a receiver device for inductive energy transmission. comprising the steps of: - detecting the possible presence of secondary coil and / or determining the rate of recovery of said secondary coil by the primary coil (27) by measuring the characteristics presented by the primary coil (27) and comparing the result of the measurements made with reference measurements; moving the primary coil (27) to align it under the secondary coil depending on the result of these measurements; characterized in that the moving step uses electromagnetic means for moving and / or positioning the primary coil (27), preferably the measuring and moving steps are performed alternately. 16. Alignment method according to claim 15 characterized in that it is initiated by the detection of the presence of an object on an interface surface (23) of said receiving device (19).