Inductive Power Transfer With Reduced Electromagnetic Interactions Within a Conductor Arrangement

Abstract

Inductive power transfer with reduced electromagnetic interactions within a conductor arrangement The invention relates to a conductor arrangement (90) for an inductive power transfer, the conductor arrangement (90) comprising at least three coils (92, 94) that are arranged along a longitudinal axis (LO) and that are formed of at least one conductor, wherein the conductor arrangement (90) comprises at least two winding heads (W) that are arranged opposite to one another and in which conductor sections of each of the coils (92, 94) extend along one another as well as along the longitudinal axis (LO), wherein, within at least one of the two winding heads (W), the conductor sections of a first and second coil (92) that extend along the longitudinal axis (LO) are arranged at a first distance (D1) to one another, the first distance (D1) being equal to or larger than zero, and the conductor section of the third coil (94) that extends along the longitudinal axis (LO) is arranged at second distances (D2) to said conductor sections of the first and second coil (92) the second distances (D2) being larger than the first distance (D1). Further, the invention relates to an inductive power transfer C arrangement (100) and methods for providing conductor arrangements (90) for an inductive power transfer.

Claims

1. A conductor arrangement for an inductive power transfer, the conductor arrangement comprising at least three coils that are arranged along a longitudinal axis and that are formed of at least one conductor, wherein the conductor arrangement comprises at least two winding heads that are arranged opposite to one another and in which conductor sections of each of the coils extend along one another as well as along the longitudinal axis, wherein, within at least one of the two winding heads, the conductor sections of a first and second coil that extend along the longitudinal axis are arranged at a first distance to one another, the first distance being equal to or larger than zero, and the conductor section of the third coil that extends along the longitudinal axis is arranged at second distances to said conductor sections of the first and second coil, the second distances being larger than the first distance.

2. The conductor arrangement according to claim 1, wherein the third coil is arranged at least partially between the first and second coil when viewed along the longitudinal axis.

3. The conductor arrangement according to claim 1, wherein the first distance and the second distances extend along an axis that is parallel to a plane in which at least one of the coils are formed.

4. The conductor arrangement according to claim 1, wherein the first distance and the second distances are horizontal distances.

5. The conductor arrangement according to claim 3, wherein the third coil has a reduced lateral dimension compared to the first and second coil, said lateral dimension extending between the winding heads.

6. The conductor arrangement according to claim 1, wherein the first distance and the second distances extend along an axis that is non-parallel to a plane in which at least one of the coils are formed.

7. The conductor arrangement according to claim 1, wherein the first distance and the second distances are vertical distances.

8. The conductor arrangement according to claim 6, wherein, within each winding head, a magnetisable material arranged between the conductor section of the third coil and a conductor section of one of the first and second coil.

9. The conductor arrangement according to claim 8, wherein magnetisable material is arranged between the respective conductor sections when viewed along an axis that is non-parallel to a plane in which at least one of the coils are formed.

10. The conductor arrangement according to claim 8, wherein the magnetisable material is formed as a projection extending at least partially in parallel to a plane in which at least one of the coils are formed.

11. The conductor arrangement according to claim 8, wherein the magnetisable material is part of a shielding assembly that extends along each winding head.

12. The conductor arrangement according to claim 1, wherein, within each winding head, a magnetisable material is placed opposite a side of the conductor section of the third coil, said side facing away from the first and second coil.

13. A conductor arrangement for an inductive power transfer, the conductor arrangement comprising at least three coils that are arranged along a longitudinal axis and that are formed of at least one conductor, wherein the conductor arrangement comprises at least two winding heads that are arranged opposite to one another and in which conductor sections of each of the coils extend along one another as well as along the longitudinal axis, wherein a magnetisable material is placed between at least two of the conductor sections within at least one of the winding heads.

14. An inductive power transfer arrangement, comprising a primary side configured to produce an electromagnetic field and a secondary side configured to receive the electromagnetic field, thereby producing a magnetic induction at the secondary side, wherein at least one of the primary and secondary sides comprises a conductor arrangement according to claim 1.

15. The inductive powder transfer arrangement according to claim 14, wherein the secondary side is arranged onboard a land vehicle and the primary side is arranged in the surroundings of the land vehicle.

16. A method for providing a conductor arrangement 90 for an inductive power transfer, comprising forming at least three coils form a conductor arrangement and such that the coils are arranged along a longitudinal axis, and such that at least two winding heads are formed that are arranged opposite to one another and in which conductor sections of each of the coils extend along one another as well as along the longitudinal axis, and such that, within at least one of the two winding heads, the conductor sections of a first and second coil that extend along the longitudinal axis are arranged at a first distance to one another, the first distance being equal to or larger than zero, and the conductor section of the third coil that extends along the longitudinal axis is arranged at second distances to said conductor sections of the first and second coil the second distances being larger than the first distance.

17. A method for providing a conductor arrangement for an inductive power transfer, comprising forming at least three coils of a conductor arrangement, such that the coils are arranged along a longitudinal axis, such that at least two winding heads are formed that are arranged opposite to one another and in which conductor sections of each of the coils extend along one another as well as along the longitudinal axis, and such that a magnetisable material is placed between at least two of the conductor sections within at least one of the winding heads.

Description

[0073] In the following, an embodiment of the invention will be described with reference to the attached schematic figures. Features which correspond to one another with regard to their type and/or function may be assigned the same reference signs throughout the figures. In the figures,:

[0074] FIG. 1 is a schematic illustration of an inductive power transfer arrangement according to an embodiment of the invention;

[0075] FIG. 2 is a schematic illustration of a secondary side or the arrangement of FIG. 1;

[0076] FIG. 3 is a detailed view of the winding head of a secondary side according to the prior art;

[0077] FIG. 4 is a detailed view of the winding head of a secondary side according FIG. 2;

[0078] FIG. 5 is a detailed view of a winding head of a secondary side according to a further embodiment of the invention;

[0079] FIG. 6 is a detailed view of a winding head of a secondary side according to a still further embodiment of the invention; and

[0080] FIG. 7 is a top view of part of the embodiment of FIG. 6.

[0081] In FIG. 1, an inductive power transfer arrangement 100 according to an embodiment of the invention is schematically shown. The inductive power transfer arrangement 100 is configured to inductively charge an electric vehicle 4. The vehicle 4 comprises wheels 7a, 7b for traveling on a track 2. For example, the vehicle 4 may be a road automobile (such as a private automobile or a bus) or may be a track bound vehicle, such as a rail vehicle. Details of the road or railway are not shown in FIG. 1.

[0082] There is an arrangement of electrically conducting material combined with (e.g. embedded in) the track 2. For example, there are three phase conductors 1a, 1b, 1c for carrying the three phases of a three-phase alternating current during operation. The phase conductors 1a, 1b, 1c form a conductor arrangement 90 in which each of the phase conductors 1a, 1b, 1c is a coil 92, 94 (see following discussion of FIG. 2).

[0083] Together with the electrically conducting material which is embedded in the track or is part of the track 2, said conductor arrangement 90 forms a primary side 102 of the inductive power transfer arrangement 100 or, differently put, forms a primary side conductor assembly. During operation, the primary side 102 produces an electromagnetic field. The magnetic field lines F are schematically indicated in FIG. 1. However, the field lines F are not completely shown. Rather, only the nearly homogeneous area of the magnetic field in the gap between the primary side 102 and the secondary side104 of the power transfer arrangement 100 on-board the vehicle 4 is illustrated by flux lines.

[0084] The vehicle 4 comprises a receiver 4b for receiving the electromagnetic field and for producing electric energy by magnetic induction. For this purpose, the receiver 4b comprises a secondary side 104 or, differently put, a secondary side conductor assembly of the arrangement 100. In the specific embodiment shown, this secondary side 104 comprises three phase lines 5a, 5b, 5c for producing a three-phase alternating current. The phase lines 5a, 5b, 5c may be coils comprising several windings of an elongated electric conductor and thus represent coils 92, 94 of a conductor arrangement 90 discussed above. Optionally, each phase line 5a, 5b, 5c may comprise or, more precisely, be formed into a plurality of coils.

[0085] FIG. 1 also schematically shows an energy storage 4a for storing the electric energy which is produced by the receiver 4b. Other electric and/or electronic parts on board the vehicle 4, which may be used for providing the produced electric energy to any electric consumer, are not shown in FIG. 1.

[0086] FIG. 2 schematically shows a top view or a bottom view of the primary side 102 or secondary side 104 of the inductive power transfer arrangement 100 of FIG. 1. In particular, it shows a top or bottom view of the conductor arrangement 90 at the respective primary or secondary side 102, 104. The direction which connects the primary side and the secondary side (i.e. the direction of the magnetic flux F extending therebetween as indicated in FIG. 1) extends perpendicular to the image plane of FIG. 2. Also, in FIG. 1 the outer members 5c, 5a and 1c, 1a of the respective conductor arrangements 90 correspond to the outer coils 92 of FIG. 2, whereas the central members 5b, 1b correspond to the central coil 94 of FIG. 2.

[0087] In FIG. 2, a longitudinal axis LO is indicated. Said axis LO would extend from left to right in FIG. 1 e.g. in parallel to the tracks 2. Also, a lateral axis LA is shown which extends orthogonally to the longitudinal axis LO. In FIG. 1, the lateral axis LA would extend orthogonally to the plane of this figure and e.g. towards the viewer. The lateral and longitudinal axes LA, LO extend within or define a horizontal plane. Note that said horizontal plane is equivalent to a plane in which at least the active sections A of the coils 92, 94 are formed. As noted above, this may be considered as a (main) plane in which the coils 92, 94 are formed. Further, a vertical spatial axis Z extends orthogonally to both of the lateral and longitudinal axes LA, LO and faces the viewer in FIG. 2. Note that in FIG. 1, the orientation of the vertical axis Z is depicted as well.

[0088] The coils 92, 94 are each marked by a distinct line. Specifically, the outer coils 92 are marked by a dotted and dashed line, whereas the central coil 94 is marked by a continuous line. It can be seen that each coil is formed as an oval or rectangularly shaped closed electric conductor arrangement, said conductor being a cable. The coils 92, 94 are similarly shaped and sized but not congruently arranged. Instead, they are shifted relative to one another along the longitudinal axis LO but arranged at same height along the lateral axis LA.

[0089] Each coil 92, 94 comprises two longer conductor sections extending along the lateral axis LA and two shorter conductor sections extending along the longitudinal axis LO, each of the respective pairs of conductor sections being parallel as well as opposite to one another. The conductor sections extending along the lateral axis LA each form active sections A of a respective coil 92, 94 and thus of the overall conductor arrangement. The conductor sections extending along the longitudinal axis LO form two opposite winding heads W that connect the active sections A. Specifically, the active sections A are spaced apart from one another along the longitudinal axis LO. Yet, they are connected by the conductor sections of the winding heads. Due to bridging the longitudinal gap between the active sections A, the winding heads' conductor sections extend along the longitudinal axis LO, even though they could be curved in case of oval windings. For illustrative purposes, a comparatively large area of the winding heads W is encircled in FIG. 2. Yet, in a strict sense, only the area in which the short conductor sections of each three coils 92, 94 extend along one another could be considered to represent an actual winding heads W. This would be equivalent to the area of the short longitudinal conductor sections of the central coils 94 in each of said encircled areas. Note that only those conductor sections extending along the longitudinal axis LO are referenced as “conductor sections within/of the winding head” or similar in the context of the embodiments.

[0090] Accordingly, in the example of FIG. 2, the coils 92, 94 are arranged at same positions (i.e. heights) along the lateral axis LA. However, they are arranged sequentially and in particular next to one another along the longitudinal axis LO.

[0091] In more detail, for each of the coils 92, 94, a geometric centre 92M, 94M is shown or, in other words, a centre of area of the coils 92, 94 (i.e. a centre of the area enclosed by the coils 92, 94). It can be seen that the central coil 94 is, especially with respect to its geometric centre 94M, arranged between the outer coils 92 along the longitudinal axis LO (and in particular between the geometric centres 92M of these outer coils 92).

[0092] Accordingly, the coils 92, 94 and especially their geometric centres 92M, 94M are spaced apart from one another or, differently put, displaced along the longitudinal axis relative to one another by equal distances (e.g. a third of a longitudinal dimension (i.e. width) of each coil 92, 94).

[0093] As a general result of the conductor arrangement depicted in FIG. 2, each coil 92, 94 forms a coil that may produce a different phase of a three-phase alternating current or may carry one phase of a three-phase alternating current during operation, depending on which of the primary or secondary side 102, 104 is considered.

[0094] Still further, in FIG. 2, a shielding assembly 96 is indicated which is made of a magnetic material. As will be evident from the following figures, said shielding assembly 96 may (with respect to the axis Z) also cover at least part of the winding heads W or extend below thereof. Also, even though the shielding assembly 96 is only depicted as extending outside of and along the winding heads W, it may also fully enclose the conductor arrangement 90 on all sides. For example, it may have an overall rectangular outline due to connecting the depicted longitudinal sections in FIG. 2 by additional lateral sections (not shown). Also, at least part of the shielding assembly 96 may extend along a side of a conductor arrangement 90 facing away from the further conductor arrangement 90 at a respective other of the primary or secondary side 102, 104. Examples of shielding assemblies 96 can be found in the above-mentioned earlier disclosure EP 2 841 293 B1.

[0095] In the following, cross sections through conductor arrangements 90 according to embodiments of the invention will be discussed. A plane of the cross sections contains or extends in parallel to the lateral axis LA as well as the vertical axis Z. Also, the cross sections only depict one of the winding heads W. Yet, it is to be understood that the respectively opposite winding head W is configured in a similar manner. This is indicated by axes of symmetry S in the following figures at which depicted members and components are mirrored. Still further, the following cross-sections relate to a secondary side 104 but the primary side 102 can be configured in an identical manner (e.g. by simply turning the depicted conductor arrangements 90 upside down).

[0096] First of all, however, an example of a prior art solution is shown in FIG. 3. More precisely, a cross-section of a winding head W of a prior art conductor arrangement 90 is shown. The different coils 92, 94 are represented by similar line-types as in FIG. 2 (i.e. dotted, dashed, continuous lines). A part of the active section A of the coils 92, 94 can be seen. In the region of the winding head W, the conductor sections of the coils 92, 94 are angled with respect to said active section A and extend into the plane of FIG. 3 towards the opposite active section A (i.e. point away from the viewer).

[0097] In a generally known manner, the conductor sections of each coil 92, 94 are vertically placed on top of one another or, in other words, are vertically stacked (see respective vertical axis Z). Adjacent conductor sections within the winding head W are thus vertically spaced apart from one another. This spacing is regular, i.e. the conductor sections have the same vertical distance to a respective directly adjacent conductor section. Also said distance is comparatively small (e.g. few centimeters) or non-existent in case of a contact between adjacent conductor sections. If no contact is desired, spacers of e.g. plastic or other electrically isolating material can be arranged between adjacent conductor sections.

[0098] Moreover, a shielding assembly 96 comprising magentisable material 110 is shown. The shielding assembly 96 covers a (vertically) upper side of the conductor arrangement 90. Close to a lateral edge, it has an enlarged angled portion 112 for receiving the winding head W. Note that the shielding assembly 96 also covers a lateral outer edge or, differently put, a lateral face 114 of the winding head W.

[0099] FIG. 3 also indicates a main course of resulting magnetic field lines 116 in the region of the winding head W, said field lines 116 occurring when operating the conductor arrangement 90 (i.e. when inductively transferring electrical energy thereto). Due to the shape of the shielding assembly 96, a large portion of the produced electromagnetic flux does not enter the surroundings but follows the shape of the shielding assembly 96. Specifically, after leaving the winding head W in a vertically upward direction, the field lines 116 are guided back towards a lower portion of the winding head W through the portion of this shielding assembly 96 that covers the lateral face 114 of the winding head W. This way, a closed circle of the magnetic field lines 116 is produced.

[0100] However, the inventors have observed that these field lines 116 extend through all conductor sections that are present in the winding head W and thus through all of the coils 92, 94. As a result, the electromagnetic interactions between the coils 92, 94 will be strong, while these coils 92, 94 are actually supposed to produce independent phases of an alternating current. This concerns in particular the central coil 94 which, due to being positioned between the outer coils 92, already experiences strong electromagnetic interactions in the region of its active sections A.

[0101] The invention seeks to overcome these problems by electromagnetically decoupling at least some of the coils 92, 94 and e.g. according to the following embodiments.

[0102] In FIG. 4, a similar cross-section as in FIG. 3 is shown. Yet, in this case, only the conductor sections of the outer coils 92 are positioned close to one another within the winding head W. Specifically, they are positioned at a comparatively small distance D1 relative to one another, which may amount to a few centimetres (e.g. less then 5 cm) or may even be zero. On the other hand, the conductor section of the central coil 94 is, within the winding head W, positioned at larger distances D2 to each of the conductor sections of the outer coils 92. Note that the distances D2 are of course different from one another but are labelled similarly to indicate that these both relate to distances of the central coil's conductor section to the further conductor sections. Still further, the distances D1, D2 are vertical distances as evident from the coordinate system in FIG. 3 which is also valid for each of the further FIGS. 4 to 6.

[0103] Accordingly, within the winding head W the conductor sections of the outer coils 92 are positioned closer to one another (distance D1) than to the conductor section of the central coil 94 (distance D2). Due to the resulting air gap between the outer coils 92 and the central coil 94, electromagnetic interactions between these coils 92, 94 and in particular and undesired influence of the outer coils 92 on the central coil 94 can be limited.

[0104] Therefore, adjusting the distances between the coils 92, 94 as depicted in FIG. 3 represents an embodiment of the invention as such, regardless of the below discussed further features of the shielding assembly 96.

[0105] Nonetheless, a further advantageous embodiment is provided by the depicted design of the shielding assembly 96 and specifically by a portion of magnetisable material 110 extending in between the conductor sections in the winding head W.

[0106] In more detail, FIG. 3 shows that the shielding assembly 96 again has a portion covering the lateral face 114 of the conductor sections within the winding head W. Yet, at a position between the conductor sections of the outer coils 92 and the conductor section of the central coil 94, a projection of magnetisable material 110 is formed which projects horizontally (i.e. along the lateral axis LA, see FIG. 3) and extends along the length of the winding head W (i.e. along the longitudinal axis LO, see FIG. 3). Said projection of magnetisable material 110 thus extends into the air gap formed by the increased distance D2 between the outer and central coils 92, 94. When viewed along the vertical axis Z, said projecting magnetisable material 110 is thus positioned in between the conductor sections of the outer coils 92 and the central coil 94.

[0107] It is evident from the below FIG. 5, that providing a respective protection of magnetisable material 110 represents an embodiment of the invention by itself. This feature may help to limit electromagnetic interactions in particular between the outer coils 92 and the central coil 94 by shielding these coils 92, 94 from one another within the winding head W. Specifically, as discussed in the following with respect to FIG. 4, it helps to concentrate the magnetic field lines 116 of each of the outer coils 92 and central coil 94 close to the respective coils 92, 94. With respect to the central coil 94, however, this may be achieved to a lesser extent compared to the embodiment of FIG. 4 due to the shielding assembly 96 not covering a lateral face and underside of said central coil 94.

[0108] Coming back to FIG. 4, it can be seen that the shielding assembly 96 also covers the lateral face 114 of the central coil 94 and comprises a further horizontal projection 120 of magnetisable material 110 that extends parallel to the horizontal projection in between the coils 92, 94. Thus, the lateral angled portion of the shielding assembly 96 or, in general, the portion of the shielding assembly 96 shielding (or surrounding) the winding head W has an E -shaped cross-section. Depending on the exact configuration, the legs of said E-shaped cross-section may have different lengths. For example, in FIG. 4 the upper leg is longer than the central and lower leg formed by the respective projections of magnetisable material 110.

[0109] Each of the lateral faces 114 of the outer coils 92 and the central coil 94 is, within the winding W, thus partially surrounded by the shielding assembly 96 and, more specifically, surrounded on three sides. This helps to concentrate the electromagnetic fields produced by these coils 92, 94 close thereto. More precisely and as depicted in FIG. 4, a large portion of the magnetic field lines 116 can be guided by the shielding assembly 96 and in particular with help of the horizontal projection in between the conductor sections, so as to produce closed circles of respective field lines 116. In particular, it can be avoided that a large portion of the field lines 116 of the outer coils 92 extend through the central coil 94, thus limiting the electromagnetic interactions between these coils 92, 94.

[0110] A further embodiment of the invention is shown in FIG. 6. In this case, the conductor sections within the winding head W are not vertically but horizontally spaced apart and, more precisely, spaced apart along the lateral axis LA (i.e. within a plane in which at least the active sections of the coils 92, 94 are formed). Specifically, the conductor section of the central coil 94 is spaced apart from the conductor sections of the outer coils 92 along the lateral axis LA by the distance D2 depicted in FIG. 6. This distance relates in particular to the lateral faces 114 of these conductor sections or, in other words, as measured between these lateral faces 114. The vertical distances between the conductor sections, on the other hand, can be regular, much like of the equidistant spacing according to FIG. 3). This limits in particular the vertical size of the winding head W. Yet, the vertical distances could also be configured according to the embodiments of FIGS. 4 and 5 to achieve a particularly strong electromagnetic decoupling between the outer and central coils 92, 94 within the winding head W.

[0111] Note that the horizontal/lateral distance between the conductor sections of the outer coils 92 is zero in FIG. 6. A respective first distance D1 between these conductor sections is thus not depicted in FIG. 6. Also, the horizontal/lateral second distances D2 between the central coil and outer coils 94, 92 is equivalent with regard to both of these outer coils 92. In the wording of the present claims, the second distances D2 of the central coil 94 to each of the further conductor sections of the outer coils 92 are thus equivalent to one another.

[0112] The shielding assembly 96, on the other hand, is configured similar to the example of FIG. 3. This also means that the magnetic field lines 116 are guided in a similar manner through all of the conductor sections within the winding head W. However, due to the distance D2, a (horizontal) length of said field lines 116 is increased. This means that the magnetic flux is weakened in particular in the region of the air gap formed by the horizontal distance D2. Again, this leads to limited electromagnetic interactions between the coils 92, 94 and in particular a limited influence of the outer coils 92 on the central coil 94.

[0113] In FIG. 7, a top view of the conductor arrangement 90 of FIG. 6 without the shielding assembly 96 is shown. Again, the horizontal displacement of the central coil 94 with respect to the outer coils 92 can be seen. Note that the term “outer” relates to the position of said coils 92 along the longitudinal axis LO. As evident from the depicted axis of symmetry S, a lateral dimension of the central coil 94 is thus reduced compared to the outer coils 92. This, however, has no significant effect on the properties of the coils 92, 94 when considering practically relevant dimensions (e.g. much larger dimensions along longitudinal axis than depicted). Thus, in said coils 92, 94 comparable currents are still induced when exposed to an electromagnetic field.