The present invention relates to a primary-side coil assembly for an inductive energy transfer system for transferring energy between a primary- and a secondary-side coil assembly.
Primary coil assemblies for inductive energy transfer systems are widely known. Simple circular, planar coils or two planar, rectangular coils are used for energy transfer on the primary side.
The disadvantage of the known primary-side coil assemblies is that the power density is often not high enough or, based on the coil assembly selected, this only interacts with a satisfactory degree of efficiency with a specific coil assembly on the secondary side.
The object of the present invention is to provide a primary-side coil assembly having a power density that is as high as possible and also, if necessary, is compatible with various secondary-side coil assemblies.
This task is achieved as per the invention with a coil assembly according to claim 1, 2 or 3. The invention is based on the general idea that the magnetic fluxes generated with the four coil regions in their phase position in relation to each other can be determined by the phase position of the coil currents in relation to each other, and consequently depending on the use of a specific or several secondary-side coil assembly types, a maximum power density can be achieved. The invention also includes embodiments, however, in which the primary-side assembly is only ever operated with a specific secondary-side coil assembly type, wherein an automatic adjustment for other secondary-side coil assembly types then no longer needs to be made. In this case, the currents must be permanently established or adjusted such that the respectively required phase positions of the magnetic flux are established in relation to each other in the coil regions of the primary-side coil assembly.
It is particularly advantageous if the primary-side assembly detects the secondary-side coil assembly type and can then establish or adjust the phase position of the coil currents accordingly. This can take place through communication between the primary- and secondary-side assemblies. It is also possible, however, that the primary-side assembly detects the secondary-side coil assembly type based on the coupling. Consequently, the primary-side control device can change the phase position of the magnetic fluxes in the coil regions of the primary-side coil assembly between several modes and define the coupling for each mode, wherein the best coupling determines the mode to be selected for the energy transfer.
In the simplest case, the four coil regions according to the invention are formed respectively by individual and, where possible, non-overlapping planar coils. A substantially higher power density can be achieved, however, if overlapping primary-side coils are used, which form the four coil regions, wherein two coils respectively encircle a coil region at least on three sides. Consequently, the four coil regions can be advantageously formed from four rectangular coils, wherein the longer sides of two rectangular coils are arranged next to each other and together respectively form a split pair coil. Both split pair coils are turned 90° in relation to each other and arranged above each other. This advantageous assembly produces a mechanical and electrical decoupling of the coils which results in magnetically decoupled circuits and higher power density due to better utilisation of the ferrite.
The two-phase coil system spatially and temporally staggered by 90° generates a spatially rotating two-pole field distribution.
The coil regions can also be described as magnetic poles since they are characterised by the fact that the magnetic flux has the same phase position everywhere inside a coil region.
If a secondary coil assembly consisting of an individual, circular secondary coil is used, the external outline of which can correspond to the shape and size of that of the primary-side coil assembly with four coil regions, then the magnetic fluxes in the four coil regions must be identical in terms of their phase position. This operating mode can also be referred to as the first mode.
If a secondary coil assembly consisting of two individual, rectangular secondary coils arranged next to each other is used, the overall external outline of which corresponds to the shape and size of the primary-side coil assembly with four coil regions, then the coil regions of the primary coil assembly respectively assigned to a secondary-side coil must respectively generate in phase magnetic fluxes. The phase position of the magnetic fluxes of the primary-side coil regions, which are assigned to different secondary-side coils, is 180° in relation to each other. This operating mode can also be referred to as the second mode.
If a secondary-side coil assembly is used, however, which, like the primary-side coil assembly, also has four coil regions, the four primary-side coil regions should generate magnetic fluxes, whose phase positions correspond to 0°, 90°, 180° and 270°. This operating mode can also be referred to as the third mode.
The coils in the coil assemblies together with capacities respectively form parallel or series resonant circuits. If series resonant circuits are used, the coils of a split pair coil can be advantageously connected in series.
The primary-side coil assembly according to the invention can consist of individual coils, advantageously four overlapping, planar windings, which are arranged parallel to a ferrite core and together with the latter form the coils and coil regions. The coil regions can be configured as square, rectangular, part circle shape (pie slice) or triangular, wherein each coil region is arranged in a quadrant of a right-angled coordinate system. Ultimately, the shape of each coil region inside a square can be configured arbitrarily. Consequently, the primary-side coil assembly can have a rectangular, in particular square, round, in particular circular or elliptical external outline. The same applies to the secondary-side coil assembly.
The planar windings must be configured in accordance with the shape of the required coil regions, such that they enclose or encircle two coil regions. Here a coil can encircle two coil regions arranged in adjacent or diagonally opposite quadrants, wherein the overlapping coils are arranged at right angles in relation to each other.
Furthermore, it is possible that at least one other coil is arranged parallel to the coil assembly with four coil regions described above, which can generate its own magnetically decoupled magnetic field. Improved coupling with a horizontal offset between the primary-side and secondary-side coil assembly can be achieved as a result.
As with all inductive energy transfer systems, the coils in the coil assembly, together with at least one capacitor, form resonant circuits. The primary-side resonant circuits are supplied by at least one controlled inverter.
It has proven advantageous if the coils of a previously described split pair coil are respectively connected in series, wherein a centre tap impedance is electrically connected with one terminal to the point of connection of both the coils of a split coil pair connected in series and with the other terminal to the midpoint/centre tap, positive or negative terminal of the intermediate circuit of the inverter.
An inductive energy transfer system having a primary coil assembly according to the invention is also claimed. The secondary coil assembly can be configured as described above.
The secondary coil assembly can also be configured in exactly the same way as the primary coil assembly, wherein only one rectifier circuit then needs to be connected downstream.
The invention is explained in greater detail below using drawings:
Depending on the type of secondary-side coil assembly A2 used, the phase position of the magnetic fluxes in the individual coil regions BEP1, BEP2, BEP3 and BEP4 can be established. The phase positions in the individual coil regions BEP1, BEP2, BEP3 and BEP4 of the primary-side coil assembly A1 can be predefined as long as only one secondary-side coil assembly type is employed or used. As soon as interoperability is required, i.e. energy is to be supplied to differently configured secondary-side coil assemblies A2 by means of the primary-side coil assembly A1, it must be possible to change the phase positions of the magnetic fluxes in the primary-side coil regions BEP1, BEP2, BEP3 and BEP4 in relation to each other.
Due to the fact that the split pair coils SPP1 and SPP2 are turned 90° in relation to each other and arranged above each other, the resulting phase positions φB1-4 of 315°, 45°, 135° and 225° are produced for the resulting magnetic flux densities B1-4 in the coil regions BEP1, BEP2, BEP3, BEP4.
A secondary-side coil assembly A2 also having four coil regions BES1-4, which is shown on the right in
In the arrangement of the secondary coil assembly A2 relative to the primary-side coil assembly A1 shown in
In the arrangement of the secondary coil assembly A2 relative to the primary-side coil assembly A1 shown in
The windings W1, W2 form the coils SP1,2. The arms WS11, WS12, WS21, WS22 of the windings W1 and W2 span the coil regions BEP1, BEP2, BEP3 and BEP4. By means of corresponding phase positions of the currents in the windings W1, W2 and SP1,2 respectively, the phase positions φB can be established for the magnetic flux densities B1-4 in the coil regions BEP1, BEP2, BEP3 and BEP4 as in the previously described embodiments.
A central impedance LPM is connected with one terminal to the point of connection
VP and with the other terminal to the centre tap MTP of the capacitive potential divider CGL1, CGL2.
It goes without saying that the secondary coil assembly A2 can be configured according to the embodiments for the primary coil assemblies described above, wherein a rectifier circuit, according to
Number | Date | Country | Kind |
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10 2013 004 180.5 | Mar 2013 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/075814 | 12/6/2013 | WO | 00 |