Method for the supply of an electrical component with electric power using an inductive charging system having a primary coil unit and a secondary coil unit

Abstract

A method for the supply of an electrical component with electric power using an inductive charging system having a primary coil unit and a secondary coil unit, where the electrical component is connected on a secondary side corresponding to the secondary coil, includes setting a rough position of the secondary coil unit relative to the primary coil unit to establish an electromagnetic coupling, displacing a primary coil in the primary coil unit relative to a primary ferrite in the primary coil unit in a preferred direction such that an electromagnetic coupling factor of the rough position of the secondary coil unit relative to the primary coil unit is increased, where the preferred direction lies in a plane of a planar basic shape of the primary ferrite, and changing a magnetically active surface area within the primary coil unit in the plane.

Claims

1. A method for the supply of an electrical component with electric power using an inductive charging system having a primary coil unit and a secondary coil unit, wherein the electrical component is connected to the secondary coil unit and wherein the primary coil unit comprises: a primary coil and a primary ferrite, wherein the primary coil is not rigidly connected to the primary ferrite such that the primary coil is moveable relative to the primary ferrite from a starting position for an electromagnetic coupling between the primary coil unit and the secondary coil unit to a charging position for the electromagnetically coupling, wherein the primary coil unit incorporates a plurality of ferrite elements, wherein the plurality of ferrite elements are arranged relative to the primary ferrite, such that the primary ferrite, along a periphery of the primary ferrite, is entirely enclosed by the plurality of ferrite elements, wherein the plurality of ferrite elements comprises groups and sub-groups of ferrite elements, wherein the primary coil unit, for each respective sub-group of ferrite elements, incorporates a respective ferrite suspension device for the constituent ferrite elements of the sub-group, and wherein one group of ferrite elements comprises a plurality of sub-groups of ferrite elements, wherein the primary coil unit, for each respective group of ferrite elements, comprises a ferrite element control unit, by which the respective ferrite suspension devices of the constituent sub-groups of ferrite elements in the group are controllable, in order to fold away or fold out the ferrite elements in a sub-group; the method comprising the acts of: setting a rough position of the secondary coil unit relative to the primary coil unit to establish the electromagnetic coupling between the primary coil unit and the secondary coil unit; displacing the primary coil in the primary coil unit relative to the primary ferrite in the primary coil unit in a preferred direction, from the starting position of the primary coil to the charging position of the primary coil, such that an electromagnetic coupling factor of the rough position of the secondary coil unit relative to the primary coil unit is increased, wherein the preferred direction lies in a plane of a planar basic shape of the primary ferrite; and changing a magnetically active surface area within the primary coil unit in the plane of the planar basic shape of the primary ferrite by folding away into the plane of the planar basic shape of the primary ferrite the ferrite elements in a group by the respective ferrite element control unit or by folding out of the plane of the planar basic shape of the primary ferrite the ferrite elements in the group by the respective ferrite element control unit.

2. The method according to claim 1, wherein changing the magnetically active surface area comprises expanding the magnetically active surface area of the primary coil unit in the plane of the planar basic shape of the primary ferrite by folding away into the plane of the planar basic shape of the primary ferrite the ferrite elements in the group by the respective ferrite element control unit to further increase a magnetic flux through the primary coil in the charging position and the secondary coil unit.

3. The method according to claim 1, wherein changing the magnetically active surface area comprises reducing the magnetically active surface area of the primary coil unit in the plane of the planar basic shape of the primary ferrite, against the preferred direction of displacement of the primary coil, by folding out of the plane of the planar basic shape of the primary ferrite the ferrite elements in the group by the respective ferrite element control unit to minimize stray magnetic fields in the primary coil and the secondary coil unit in the charging position.

4. The method according to claim 2, wherein changing the magnetically active surface area further comprises reducing the magnetically active surface area of the primary coil unit in the plane of the planar basic shape of the primary ferrite, against the preferred direction of displacement of the primary coil, by folding out of the plane of the planar basic shape of the primary ferrite the ferrite elements in the group by the respective ferrite element control unit to minimize stray magnetic fields in the primary coil and the secondary coil unit in the charging position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1a (Prior art) depicts an overhead view of an inductive charging system for the charging of a vehicle.

(2) FIG. 1b (Prior art) depicts a primary charging unit, secondary charging unit and lines of magnetic flux upon the establishment of the electromagnetic coupling of a primary coil and a secondary coil in the inductive charging system.

(3) FIG. 2a (Prior art) depicts an overhead view of an inductive charging system for the charging of a vehicle, with the offset positioning of the primary charging unit and the secondary charging unit during the inductive charging of a vehicle.

(4) FIG. 2b (Prior art) depicts a primary charging unit, secondary charging unit and lines of magnetic flux upon the establishment of the electromagnetic coupling of a primary coil and a secondary coil in the inductive charging system, with the primary coil and the secondary coil in an offset position.

(5) FIG. 3 depicts a primary and secondary coil unit with a moveable primary coil.

(6) FIG. 4 depicts a primary and secondary coil unit, with a moveable primary coil and moveable ferrite elements.

(7) FIG. 5 depicts a charging system comprising a primary coil unit with a moveable primary coil and comprising a secondary coil unit with folded-out ferrite elements and folded-away ferrite elements.

(8) FIG. 6 depicts an overhead view of the primary coil unit, with an arrangement of foldaway ferrite elements along the periphery of the primary ferrite.

DETAILED DESCRIPTION OF THE DRAWINGS

(9) According to the prior art, initially FIG. 1a shows an overhead view of a vehicle (1) in the z-axis, according to the axis coordinate system of vehicles which is known by a person skilled in the art. The vehicle incorporates a secondary charging unit (3), by means of which the vehicle, using an off-board primary charging unit (2), can be inductively supplied with electric power, preferably for the charging of an in-vehicle electrical or electrochemical energy store.

(10) For charging purposes, according to FIG. 1b, the secondary charging unit is positioned at a specific distance in the z-direction (the vertical axis in the spatial reference system). With respect to the x-direction (longitudinal vehicle axis) and the y-direction (transverse vehicle axis), the secondary charging unit is ideally to be positioned such that, in an overhead view (see FIG. 1a) an electric coil of the secondary charging unit (3a), insofar as possible, is centered on or coincident with an electric coil of the primary charging unit (2a). In this ideal position, in which the coils are positioned with no lateral x-y-offset, electromagnetic coupling between the two coils for the purposes of energy transmission is generally optimal. Only the z-direction then influences the degree to which the magnetic field lines of the primary field (10) permeate the secondary coil, such that electric power is inducible on the secondary side. The contribution of stray fields (11), which do not permeate the secondary coil and do not contribute to electromagnetic power transmission is ideally minimized accordingly. The magnetic flux on both the primary side and the secondary side of ferrites is employed in a targeted manner, i.e. of one ferrite in the primary charging unit (2b) and of one ferrite in the secondary charging unit (3b), which have a high magnetic conductivity, for the spatial straightening of the magnetic field lines such that the active component of the alternating magnetic field during charging is increased, and losses associated with stray magnetic field components are minimized.

(11) According to the prior art represented in FIGS. 1a and 1b, a problem frequently occurs in practice wherein, during the charging of the vehicle, an offset in the x-y-direction of the vehicle must be anticipated in relation to the primary charging unit (c.f. the prior art according to FIGS. 2a and 2b), as ideal positioning according to FIGS. 1a and 1b cannot be achieved in a controlled manner. In consequence, the stray field component which, according to FIG. 2b, does not contribute to charging, is increased in comparison with the situation represented in FIG. 1b, such that, in general, the at least theoretically achievable charging capacity cannot be achieved in practice, or can only be achieved with high losses.

(12) FIG. 3 shows one form of embodiment of a primary coil unit (6) according to the invention, which overcomes the disadvantage known from the prior art, and incorporates an electric primary coil (6a) and a primary ferrite of a planar basic shape (6b). For the transmission of electromagnetic power from the primary coil unit to a secondary coil unit (7), which can also be a secondary coil unit having a secondary coil (7a) and a secondary ferrite (7b) from the prior art, a particularly advantageous arrangement is useful, wherein the primary coil is displaceably supported relative to the primary ferrite, perpendicularly to the z-axis. The primary coil unit and the secondary coil unit constitute an inductive charging coil system, wherein the secondary coil unit is integrated in the vehicle and the primary coil unit is located externally to the vehicle. In the interests of the simplification of representation, the requisite electronic circuits for the actuation of the coil units are not represented. If the vehicle is to be charged, for example, i.e. a transmission of power from the primary side to the secondary side takes place, the vehicle is parked in a rough position relative to the primary coil unit. The offset is compensated by the subsequent displacement of the primary coil. By means of the offset, which is detectable using a positioning system of the vehicle relative to the primary coil unit, the optimum charging position to be set for the primary coil in the x-y-plane of the primary ferrite is established.

(13) For the optimization of the efficiency of electromagnetic power transmission, the primary coil, in the event of an offset of the secondary coil relative to the primary coil in the x- and/or y-direction, is displaced from a starting position (represented by broken lines) to a charging position. The displaced primary coil (6a′), relative to the secondary coil, a fixed position of which is assumed during the charging in accordance with the reference system of vehicle axes which will be known by a person skilled in the art, is ideally electromagnetically positioned in relation to the x- and y-axis. This means that, in the charging position of the primary coil, electromagnetic coupling, regardless of any further scope for optimization with respect to the z-axis, achieves a localized maximum value as a function of the relative position of the two coils in the x- and y-direction. This is indicated in FIG. 3 by the magnetic field components (magnetic field lines 10) which contribute to power transmission. In the charging position of the primary coil, stray field components are minimized.

(14) FIGS. 4, 5 and 6 show a further form of embodiment of the primary coil unit according to the invention. The primary ferrite is supplemented by ferrite elements (21a to f) of the primary coil unit. The ferrite elements are essentially comprised of the same magnetically conductive material as the primary ferrite. Optionally or additionally, the ferrite elements incorporate screening elements (22a to f), wherein one screening element respectively is assigned to each ferrite element. The screening elements are configured as magnetic screening plates. The ferrite elements are configured, either individually or in groups, in a foldaway or fold-out arrangement in the plane of the primary ferrite, which assumes a planar basic shape. In the folded-away state, the primary ferrite and the ferrite elements, or the ferrite elements, are arranged in mutual contact. In the folded-away state (c.f. 21d to f in FIGS. 4 and 5), a direct magnetically-conductive transition thus exists between the primary ferrite and the ferrite elements. The magnetic flux can thus be conducted, with reduced electromagnetic losses, from the primary ferrite via the ferrite elements which are folded-away into the plane of the primary ferrite. Where ferrite elements are folded-out of this plane (c.f. 21a to c in FIGS. 4 and 5), magnetic conduction of the magnetic flux from the primary ferrite to the folded-out ferrite elements is suppressed, given that, in the vicinity of the two-fold material transition from the primary ferrite to air and vice versa, and of the screening elements which are arranged virtually perpendicularly to the plane of the primary ferrite, magnetic field lines, in the direction of propagation of the folded-out ferrite elements, are screened (c.f. screened stray field line 12).

(15) From the overhead view in FIG. 6, it will be seen that the primary charging unit incorporates a plurality of ferrite elements (23a-c, 25a-c, 27a-c, 29a-c, 31a-c, 33a-c, 35a-c and, analogously, so forth), arranged along the periphery of the primary ferrite. The ferrite elements (21a, 23a, 25a, 27a, 29a, 31a, 33a, 35a) constitute a sub-group of ferrite elements, to which one first ferrite suspension device (101) is common. The ferrite suspension device constitutes an axis, around which the constituent ferrite elements of the sub-group are hinged.

(16) The hinging of ferrite elements is executed by a ferrite element mechanism (first ferrite element mechanism 100). A second and a third ferrite suspension device (102, 103) are assigned to the first ferrite element mechanism, which respectively comprise further sub-groups of ferrite elements. The sub-groups of ferrite elements assigned to the ferrite element mechanism constitute a group of ferrite elements. The three ferrite suspension devices assigned to the first ferrite element mechanism can be actuated in a mutually independent manner by the ferrite element mechanism.

(17) The ferrite element mechanism can hinge the entire group of ferrite elements, by the rotation of the associated ferrite suspension devices, or individual sub-groups of ferrite elements, by the rotation of the relevant individual ferrite suspension device. Along the periphery of the primary ferrite, three further ferrite element mechanisms, correspondingly arranged with respect to the first ferrite element mechanism and functioning accordingly (c.f., for example, second ferrite element mechanism 120), are located. The second ferrite element mechanism serves the three ferrite suspension devices (121, 122, 123), which respectively incorporate sub-groups of ferrite elements. Actuation of the ferrite element mechanism can be executed via a mechanical coupling with the positioning motors, which are designed for coil displacement. A fixed assignment of the hinging state of individual ferrite sub-groups in relation to the position of the primary coil in the x-y-plane is possible. Accordingly, hinging can be tripped by displacement along the displacement path executed by the positioning motors of the coil.

(18) According to a further form of embodiment of the invention, all the ferrite elements may be individually hinged, i.e. independently of all the other ferrite elements respectively.

(19) With reference to FIG. 5, an embodiment of the method according to the invention is described, by means of which an electric power supply is delivered to an electrical component which is connectable, on the secondary side, to a charging system comprising a primary coil unit (6) and a secondary coil unit (7).

(20) The secondary coil unit is roughly positioned, relative to the primary coil unit. In a further step, the primary coil (6a), relative to the primary ferrite (6b), is displaced into the charging position (6a′). Optionally or additionally, the ferrite elements which establish the optimum ferrite profile of the displaced primary coil are folded away into the plane of the primary ferrite, in order to guide the magnetic field lines of the power-transmitting alternating magnetic field through the two coils with the maximum possible reduction of losses. Moreover, the ferrite elements which are arranged with a substantial clearance from the displaced primary coil, and do not contribute to the improved coupling of the coils, are optionally or additionally folded out of the plane of the primary ferrite, in order to screen out or suppress any stray magnetic fields which transmit no power. It is advantageous if the displacement path of the primary coil and the offset of the primary coil unit and the secondary coil unit in the rough position are determined or monitored prior to the commencement of the positional optimization of the primary coil within the primary coil unit. It can thus be determined which ferrite elements need to be hinged, in order to constitute the magnetically active surface by the foldaway or fold-out of ferrite elements whereby the primary coil, in the charging position, will be centered in relation to said surface.

LIST OF REFERENCE CHARACTERS

(21) 1 Vehicle 2 Primary charging unit 2a Coil of primary charging unit 2b Ferrite of primary charging unit 3 Secondary charging unit 3a Coil of secondary charging unit 3b Ferrite of secondary charging unit 6 Primary coil unit 6a Primary coil 6a′ Displaced primary coil 6b Primary ferrite 7 Secondary coil unit 7a Secondary coil 7b Secondary ferrite 10 Magnetic field lines 11 Stray field lines 12 Screened stray field line 21a-f Respective ferrite elements 22a-f Respective screening elements 23a-c Respective ferrite elements 25a-c Respective ferrite elements 27a-c Respective ferrite elements 29a-c Respective ferrite elements 31a-c Respective ferrite elements 33a-c Respective ferrite elements 35a-c Respective ferrite elements 100 First ferrite element mechanism 101 First ferrite suspension device, associated with the first ferrite element mechanism 102 Second ferrite suspension device of the first ferrite element mechanism 103 Third ferrite suspension device of the first ferrite element mechanism 120 Second ferrite element mechanism 121 First ferrite suspension device of the second ferrite element mechanism 122 Second ferrite suspension device of the second ferrite element mechanism 123 Third ferrite suspension device of the second ferrite element mechanism

(22) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.