Transferring electric energy to a vehicle by induction
The invention relates to a system for transferring electric energy to a vehicle, in particular
to a road automobile or to a track bound vehicle such as a light rail vehicle (e.g. a tram).
Examples of track bound vehicles are conventional rail vehicles, mono-rail vehicles,
metros and busses (which may be guided on the track by optical means or mechanical
means other than rails).
Track bound vehicles, in particular vehicles for public passenger transport, usually
comprise a contactor for mechanically and electrically contacting a line conductor along
the track, such as an electric rail or an overhead line. Typically, at least one propulsion
motor on board the vehicles is fed with the electrical power from the external track or line
and produces mechanic propulsion energy. In addition or alternatively, the transferred
energy can be used for operating auxiliary systems of the vehicle. Such auxiliary systems,
which do not produce traction of the vehicle, are, for example, lighting systems, heating
and/or air conditioning system, the air ventilation and passenger information systems. Not
only track-bound vehicles (such as trams), but also road automobiles (for example having
four wheels with tyres to drive on a road) can be operated using electric energy.
If continuous electric contact between the travelling vehicle and an electric rail or wire
along the route is not desired, electric energy can either be withdrawn from an on-board
energy storage or can be received by induction from an arrangement of electric lines of
the route.
The transfer of electric energy to the vehicle by induction forms a background of the
invention. A route side (primary side) conductor arrangement produces a magnetic field,
which is in particular a component of an alternating electromagnetic field. The field is
received by a coil (secondary side) on board of the vehicle so that the field produces an
electric voltage by induction. The transferred energy may be used for propulsion of thevehicle and/or for other purposes such as providing auxiliary systems of the vehicle (e.g.
the heating and ventilating system) with energy.
Generally speaking, the vehicle may be, for example, a vehicle having an electrically
operated drive motor. However, the vehicle may also be a vehicle having a hybrid drive
system, e.g. a system which can be operated by electric energy or by other energy, such
as energy provided using fuel (e.g. natural gas, diesel fuel, petrol or hydrogen).
WO 95/30556 A2 describes a system wherein electric vehicles are supplied with energy
from the roadway. The all-electric vehicle has one or more on-board energy storage
elements or devices that can be rapidly charged or supplied with energy obtained from an
electric current, for example a network of electromechanical batteries. The energy storage
elements may be charged while the vehicle is in operation. The charging occurs through a
network of power coupling elements, e.g. coils, embedded in the track. Induction coils are
located at passenger stops in order to increase passenger safety.
US 4,836,344 discloses an electrical modular roadway system adapted for transmitting
power to and controlling inductively coupled vehicles travelling thereon. The system
comprises a plurality of elongated, electrically connected inductor modules arranged in an
aligned end to end spaced apart order to form a continuous vehicle path. Each module
has a magnetic core and power windings which generate a magnetic field extending
above the road surface. The modules are embedded in the ground so as to be flush with
the roadway surface over which a vehicle can travel. Each module is an elongated
structure of uniform width and thickness so that they can be easily fabricated in quantity
and readily installed in a roadbed with a minimum of labor and equipment. Each module
comprises an iron core around which is wrapped a power winding comprising a series of
coils.
Although the electric conductors are arranged immediately above the ground or are buried
in the ground, there may be systems or devices below the conductor arrangement and,
consequently, electromagnetic compatibility (EMC) requires to keep intensities of
electromagnetic fields or magnetic fields small.
It is an object of the present invention to provide a system of the kind described above
and a method of building such a system, which reduces electromagnetic field intensionsbelow the conductor arrangement and does not significantly deteriorate the efficiency of
the transfer of energy by induction to the vehicle. Furthermore, the amount of expensive
material, such as ferromagnetic material shall be kept small.
It is a basic idea of the present invention to use a combination of a shield which shields
the field produced by the conductor arrangement and of a magnetic core.
Principally, a shield, for example a layer of aluminium sheets, is usually sufficient to
reduce field intensities below the conductor arrangement. Therefore, a shield could help
avoiding the use of expensive ferromagnetic material, such as ferrite. However, especially
for preferred conductor arrangements which are operated using alternating electric
currents at frequencies which are resonant frequencies of the respective conductor
arrangement on the secondary side of the vehicle, the shield would put the total
arrangement consisting of the primary side and secondary side conductor arrangement
out of tune with respect to effective transfer of energy (which should take place at the
resonant frequency of the secondary side). In addition, the shielding effect of electrically
conductive material is produced by eddy currents, so that the shielding effect causes
energy losses.
On the other hand, the sole use of magnetic core material would increase magnetic flux,
but would also put the primary side/secondary side conductor arrangement out of tune.
Principally, it is possible to reduce the field intensity below the primary side conductor
arrangement by providing a layer of magnetic core material (ferromagnetic material) below
the conductor arrangement. Due to the ferromagnetic properties, the magnetic flux lines
would be guided within the layer nearly parallel to the layer surfaces, so that the flux
below or beyond the magnetic core material would be nearly zero. However, this would
require a substantial amount of magnetic core material, since the layer width (in horizontal
direction) needs to be as large as the width of the primary side conductor arrangement,
especially if the electric lines of the conductor arrangement follow a meandering path
extending in the direction of travel (as preferred, see below). Therefore, the width of the
conductor arrangement would be in the range of some tens of centimetres for a typical
railway or motor vehicle route and the required amount of magnetic core material would
be extremely large.Therefore, a combination of a shield of electrically conducting material (which is not
ferromagnetic) and a magnetic core is used. Preferably, the amount of magnetic core
material and the geometric configuration of the arrangement consisting of the magnetic
core and the shield is adapted in such a manner that the total system of the primary side
conductor arrangement and the secondary side conductor arrangement in the vehicle or
on the vehicle are in tune with respect to resonant frequency transfer of electromagnetic
energy. I.e. the frequency of the electromagnetic field which is produced by the primary
side conductor arrangement causes an induction of electromagnetic current at the
resonant frequency of the secondary side conductor arrangement. The electrically
conductive shield material has the effect of reducing the resonance frequency and the
magnetic core material has the effect of increasing the resonance frequency. Therefore, a
combination of a shield and a magnetic core can produce an arrangement which does not
alter the resonance frequency of the secondary side conductor arrangement due to
compensating effects.
In practice, the shield can be provided first, and the amount and/or geometric
arrangement of the magnetic core material can be varied to find the combination of shield
and magnetic core which has the desired effect on the resonance frequency (namely
preferably no effect).
In particular, the magnetic core material is placed below the electric line or lines of the
primary side conductor arrangement which produce the electromagnetic field. In contrast
to the arrangement disclosed in US 4,836,344 (see above) the primary side electric line or
lines are not wound around the magnetic core. Rather, it is preferred that the electric line
or lines of the primary side conductor arrangement extend substantially horizontally, which
means that curves and bends of the electric line or lines extend within a substantially
horizontal plane. "Horizontal" refers to the case that the track or road on which the vehicle
travels does not have an inclination. If there is such an inclination, the horizontal plane is
preferably also inclined to follow the inclination and extension of the track or route. The
extension of the electric line or lines within the substantially horizontal plane is in contrast
to the descending and ascending extension of an electric line which is wound around a
magnetic core, for example according to US 4,836,344.
Preferably, the magnetic core extends in the direction of travel, in particular continuously,
i.e. without interruption. However, small gaps between consecutive blocks of magneticcore material are not considered to be interruptions. On the other hand, an interruption will
be a gap which is wider than the width of the electric line or lines of the primary side
conductor arrangement.
In particular, the magnetic core may have a width of less than 30 %, preferably less than
20 % of the width of the primary side conductor arrangement (excluding any electric
connections to devices sideways of the track or route).The basic finding behind the idea of
using a narrow magnetic core extending in the direction of travel is that a shield of
electrically conducting material which has a width of the same order of magnitude as the
width of the conductor arrangement sufficiently shields the areas below the shield against
magnetic fields and the magnetic core sufficiently compensates the effect of the shield,
even if the magnetic core is narrow. As mentioned above, the compensation is not only for
keeping the total system in tune with respect to the resonance frequency of the secondary
side, but the compensation also has the effect that the magnetic flux of the field in the
range between the primary side and the secondary side is not smaller or not significantly
smaller than the flux without shield. In case of the preferred embodiment in which line
sections of the electric line or lines of the conductor arrangement extend transversely to
the direction of travel, a narrow magnetic core would result in a high magnetic flux in the
area above the magnetic core, but would not significantly increase the flux in other areas
between the primary side conductor arrangement and the secondary side conductor
arrangement. However, the total magnetic flux over the extension of such a transversely
extending electric line section is increased by the magnetic core. The total magnetic flux
can be, for example, calculated by integrating the magnetic flux over the length of the
transversely extending line section.
Instead of only one magnetic core, the system may comprise two or more magnetic cores
extending in the direction of travel. Such a plurality of magnetic cores increases the
homogeneity of the magnetic flux in the direction of transversely extending line sections.
For example, the desired compensation effect produced by the magnetic core or magnetic
cores can be set by varying the thickness of the magnetic core in vertical direction and/or
the distance of the magnetic core to the electric line or lines and/or to the shield. "Varying"
means finding a configuration of the combination of the primary side electric conductor
arrangement, the shield and the magnetic core or cores. For a given configuration, thethickness of the magnetic core or cores is preferably constant over the extension in the
direction of travel.
For example, the material of the magnetic core is placed in grooves and/or recesses of
pre-fabricated modules adapted to carry the material and to fix the alternating current line
or lines. An example of such a module will be described below. Blocks consisting of the
magnetic core material may be fixed on the pre-fabricated module using adhesive.
In particular, the following is proposed: A system for transferring electric energy to a
vehicle, in particular to a road automobile or to a track bound vehicle such as a light rail
vehicle, wherein the system comprises an electric conductor arrangement for producing a
magnetic field and for thereby transferring the energy to the vehicle, wherein the electric
conductor arrangement comprises at least one current line, wherein each current line is
adapted to carry the electric current which produces the magnetic field or is adapted to
carry one of parallel electric currents which produce the magnetic field and wherein:
- the current line or lines extend(s) at a first height level,
- the system comprises an electrically conductive shield for shielding the magnetic
field, wherein the shield extends under the track and extends below the first height
level, and
- a magnetic core extends along the track at a second height level and extends above
the shield.
Furthermore, a method of building a system for transferring electric energy to a vehicle is
proposed, in particular for transferring electric energy to a road automobile or to a track
bound vehicle such as a light rail vehicle, wherein an electric conductor arrangement for
producing a magnetic field and for thereby transferring the energy to the vehicle is
provided, wherein at least one current line is provided for the electric conductor
arrangement, each current line being adapted to carry the electric current which produces
the magnetic field or is adapted to carry one of parallel electric currents which produce the
magnetic field and wherein:
- the current line or lines is/are arranged to extend at a first height level,
- an electrically conductive shield is provided for shielding the magnetic field, wherein
the shield is arranged so that it extends under the track and so that it extends below
the first height level, and- a magnetic core is provided so that it extends along the track at a second height
level and so that it extends above the shield.
Extending at a first height level means that the current line or lines extend within a range
of heights with reference to a hypothetical plane (for example in case of a rail vehicle a
plane including the surfaces of the rails or in case of a road automobile the surface of the
road) on which the vehicle travels. However, parts of the alternating current line or lines
may extend at a different height level, in particular below the first height level. These parts
may be connections of the alternating current line or lines from devices (such as switches,
inverters, capacitors, inductors and combinations thereof) sideways of the track to line
sections in and/or under the track which produce the electromagnetic field for providing
the vehicle with energy. This means that at least a majority (in terms of the length of the
line) of line sections of the alternating current line or lines extends at the first height level.
The second height level at which the magnetic core extends may be below the first height
level, wherein the magnetic core is preferably provided so that it extends between the
shield and the current line or lines.
The magnetic core is preferably provided so that it extends in the direction of travel.
Advantages and embodiments are described above.
An arrangement of electrical conductors along the track can be realised in a variety of
ways. In principle, the conductors or lines can be cables laid in the ground as usual in
road construction or underground engineering. However, especially for road construction,
pre-fabricated modules having grooves or other means for receiving the line or lines are
favourable.
In particular, a route for vehicles driving on a surface of the route, in particular for road
automobiles, may have the following features:
- the route comprises a plurality of shaped blocks adapted to position and/or to hold a
plurality of line sections of one or more electric lines,
- each shaped block comprises recesses forming spaces and/or projections delimiting
spaces for receiving at least one of the line sections,
- the electric line or lines extend(s) through the spaces,- the electric line or lines extend(s) along the surface of the route in and/or about the
travelling direction of vehicles which are driving on the route,
- the shaped blocks and the electric line or lines are supported by a base layer of the
route,
- the shaped blocks and the electric line or lines are covered by a cover layer of the
route,
- the material of the cover layer is also located in regions of the route sideways of the
shaped blocks so that the shaped blocks and the cover layer form an integrated layer
on top of the base layer.
Preferably, the shield is placed between the base layer and the shaped blocks.
In particular, the material of the magnetic core is placed in grooves and/or recesses of
pre-fabricated modules (such as the shaped blocks mentioned above) so that the modules
carry the material, wherein the current line or lines is/are fixed by the modules. For
example, the electrically conductive shield can be integrated in a pre-fabricated track
module or can be attached to the module, before the module is placed on site during the
construction of the track or route. However, it is preferred to place the electrically
conductive shield first and then to place the module or parts of the module on top of the
shield. Optionally any additional material and/or element can be placed on top of the
shield, before a shaped block of the module for positioning electric line sections is placed.
Most preferred, the current line or lines are arranged so that it/they comprise(s) a plurality
of line sections extending transversely to the direction of travel. Transversely extending
line sections for providing the vehicle with energy while travelling wherein the line
sections are part of a meandering path followed by the line, have the advantage that
magnetic fields sideways of the track compensate each other. Especially these (and
preferably all) transversely extending line sections are located at the first height level.
Although not preferred, parts of other line sections which connect the transversely
extending line sections may extend below the first height level and even below the shield.
Furthermore, transversely extending line sections have the advantage that the secondary
side, where induction takes place on the vehicle, may have a varying distance to the
primary side conductor arrangement. The combination of a shield and a magnetic core will
still have no effect on the secondary side if the distance between the primary side and thesecondary side is not greater than about 30 % of the length of the transversely extending
line section.
The shield material is a non-ferromagnetic material, but electrically conductive material.
Magnetic fields produce eddy currents in the shield material which in turn compensate the
magnetic field beyond the shield.
The shield may extend substantially parallel to the track on which the vehicle may travel.
The shield may extend substantially horizontal, in particular in a layer. "Parallel" means
that the shield extends in a horizontal plane or substantially horizontal plane (see above) if
the vehicle is travelling along a horizontal or substantially horizontal plane. For example,
in case of a road vehicle, the shield extends parallel or substantially parallel to the surface
of the road.
The shield may comprise a plurality of sheets of electrically conductive material, e.g.
aluminium sheets. Alternatively, the shield may be a mesh of metal, for example copper.
For example, the shield may be integrated in concrete or other material of a pre-fabricated
track module. In this case, the shield is protected against damage. The shield, in particular
the mesh, may be bolted or otherwise fixed to the bottom part of the track or route
construction. On the other hand when a shield in form of metal sheets is placed on site,
where the track or route is to be built, the risk of damage is small and it can be fixed by
placing a layer of building material, such as concrete or asphalt on top of the sheets. In
particular, the shield may be placed between horizontally extending layers of other
material, such as between a base layer and an intermediate or top layer.
The shield may extend in a (preferably, with respect to the direction of travel continuously
extending) layer below the track on which the vehicle may travel. Preferably, there are no
significant gaps between elements (e.g. sheets) of the shield. Preferably, any gap is
smaller than the width of the electric line or lines.
Preferably, the magnetic field which is produced by the electric conductor arrangement, is
the magnetic field component of an alternating electromagnetic field, i.e. an alternating
current flows through the electric line or lines for producing the magnetic field. In addition
it is preferred that the at least one current line is an alternating current line, wherein each
alternating current line is adapted to carry the only phase or one of plural phases(preferably one of three phases) of an alternating electric current. The frequency of the
alternating current which flows through the conductor arrangement may be in the range of
1-1 00 kHz, in particular in the range of 10-30 kHz, preferably about 20 kHz.
The material of the magnetic core has preferably a relative permeability µ in the range
between 300 and 10.000. Ferrite or a ferrite compound are preferred as material of the
magnetic core.
Examples and preferred embodiments of the invention will be described with reference to
the attached figures which show
Fig. 1 schematically a road having two lanes, wherein electric lines are laid under the
surface of one of the lanes using pre-fabricated shaped blocks,
Fig. 2 a vertical cross section through a first preferred embodiment of a route, for
example part of the road shown in Fig. 1,
Fig. 3 an exploded view of part of Fig. 2,
Fig. 4 a perspective view of a preferred embodiment of a shaped block, which can be
used as a support element for supporting electric lines, in particular cables,
Fig. 5 a top view of the shaped block shown in Fig. 4,
Fig. 6 a vertical cross-section through half of the block of Fig. 4 and 5,
Fig. 7 a vertical cross section through a second preferred embodiment of a route,
namely a track of a rail vehicle,
Fig. 8 an exploded view of a cross-section of a second first embodiment of a railway
track,
Fig. 9 consecutive segments of a conductor arrangement which may be integrated in
the route, for producing an electromagnetic field,
Fig. 10 a preferred embodiment of a three-phase conductor arrangement at the transition
zone of two consecutive segments of the conductor arrangement, wherein a c ut
out of at least one shaped block is used to direct cables within the route to
devices and/or connections sideways of the route,
Fig. 11 an arrangement similar to the arrangement shown in Fig. 10, wherein the cut-out
is used to form two star point connections of the three phases of the consecutive
segments,
Fig. 12 schematically a simple construction of a route comprising an electric line section
extending transversely to the direction of travel and a magnetic core,Fig. 13 schematically a side of view of a system for inductively transferring energy to a
vehicle, including the primary side and the secondary side electric lines,
Fig. 14 a side view of an arrangement similar to Fig. 13, but including a shield, and
Fig. 15 a side view of an arrangement similar to Fig. 13 and 14, but including a magnetic
core.
The schematic top view of Fig. 1 shows a road 1 having two lanes 19a, 19b. The lanes 19
are limited by a solid line 3a, 3b at the outer margins and are limited by a common dashed
line made of line segments 9a, 9b, 9c, 9d, 9e, 9f, 9g, 9h. Consequently, the direction of
travel extends from left to right or from right to left in Fig. 1. The width of the lanes 19 is
large enough so that a vehicle can travel on either lane 19a or lane 19b or so that two
vehicles can travel next to each other on the lanes 19.
One of the lanes, namely lane 19a, is equipped with a conductor arrangement 7a, 7b, 7c
for producing an electromagnetic field. The conductors 7 (for example three electric phase
lines in each segment of the conductor arrangement) and shaped blocks 4, which hold the
conductors in place, are not visible in practice, if the road is viewed from above. However,
Fig. 1 shows the conductors 7 and the line of consecutive shaped blocks 4a, 4b, 4c, 4d,
4e, 4f, 4g. The line of consecutive shaped blocks continues towards the right beyond the
limits of Fig. 1. The conductor arrangement comprises at least three consecutive
segments 7a, 7b, 7c which can be operated separately of each other. This means, for
example, conductor 7a is operated while a vehicle (not shown) travels above the segment
whereas the other segment 7b, 7c are not operated. If the vehicles reaches segment 7b,
this segment is switched on and segment 7a is switched off. Corresponding switches
and/or inverters may be integrated in devices 52a, 52b, 52c shown in the top region of
Fig. 1.
The preferred way of laying the conductors 7 is to form a meandering path or paths, which
means that the conductor has sections that extend transversely to the direction of travel.
For example, conductor 7a has three transversely extending sections at shaped block 4a,
one transversely extending section at the transition zone to consecutive block 4b, three
transversely extending sections in the region of block 4b and one transversely extending
section at block 4c where conductor 7a is connected to device 52b. In practice, it is
preferred to use at least two phases for each segment of the conductor arrangement.In the middle section of Fig. 1 there are two parallel lines extending transversely to the
direction of travel. These lines are lines at the end of route segments having a gap 200
between each other for allowing relative movement and/or thermal expansion or
contraction. The gap 200 is located between two consecutive shaped blocks 4c, 4d and
conductor 7b extends across the gap 200 which may be filled with an elastically
deformable material, such as bitumen.
Fig. 2 shows a vertical cross section through a preferred embodiment of a route, wherein
the direction of travel for vehicles travelling on the route extends perpendicularly to the
image plane of Fig. 2. Fig. 2 may show, for example, a cross section of lane 19a of Fig. 1
and shows a cross section of an emergency lane which may be located in Fig. 1 in the top
region where the devices 52 are shown. The emergency lane is indicated in Fig. 2 by
reference numeral 29. Sideways, on the right hand side of emergency lane 29, one of the
devices 52 is shown in Fig. 2.
Lane 19a comprises a base layer 3 1 which may have, for example, a layer thickness of
20 cm. On top of the base layer 3 1 , a layer 20 of electrically conducting material (such as
aluminium plates) is laid, for example having a thickness of 5 mm. The purpose of the
layer 20 is to shield the electromagnetic field, i.e. to prevent or reduce electromagnetic
waves below the layer 20. The layer 20 is narrower than the width of the lane 19a and
may be in the range of the width of shaped block 4 which is placed above layer 20.
Shielding layer 20 is embedded in an intermediate layer 33 which may have a thickness of
5 cm, for example. On top of intermediate layer 33, shaped block 4 is placed, for holding
electric lines 17, for example in the meandering manner similarly to the arrangement
shown in Fig. 1. Block 4 may have a thickness of 15 cm, for example. The connection of
electric line 17 from block 4 downwards to the upper surface of intermediate layer 33 and
sideways through emergency lane 29 to device 55 is shown in Fig. 2.
Block 4 is embedded in a cover layer 35, which may have a thickness of 20 cm.
Optionally, a top layer 37 may be provided to form the surface of lane 19a and the
emergency lane 29.
Base layer 3 1 extends over the whole width of lane 19a. Emergency lane 29 may have a
base layer 3 1a of the same material, but preferably having a smaller thickness of forexample 8 cm. Cover layer 35 extends over the whole width of lane 19a, which means
that it has regions on both sides of block 4 (which are regions sideway of the shaped
block in the wording used above) and which means that the thickness of cover layer 35
sideways of block 4 is greater than the thickness of the cover layer 35 on top of block 4.
Emergency lane 29 may have a cover layer 35a of the same material having a constant
thickness. However, in order to shield the conductor 17, a layer 2 1 of electrically insulating
material, for example aluminium (e.g. having a thickness of 1 cm) may be located at the
bottom of cover layer 35a immediately above the connection of conductor 17. By such a
shielding layer 2 1 which preferably extends over the whole widths of emergency lane 29,
electromagnetic emission to the ambiance is significantly reduced. If segments of the
conductor arrangement are operated only while a vehicle is travelling on the segment, the
vehicle shields the ambience from the electromagnetic field produced by the conductor
arrangement. Therefore, shielding the section of the conductor 17 between the
emergency lane 29 and the shaped block 4 would result in a minor improvement only.
The base layer may be made of sand cement. The intermediate layer 33 may be made of
asphalt. The shaped block 4 and the cover layer 35 may be made of fibre concrete.
Fig. 3 shows an exploded view of the construction of lane 19a corresponding to the
construction shown in Fig. 2. The same reference numerals refer to the same parts of the
construction.
Since shielding layer 20 is provided before intermediate layer 33 is produced, intermediate
layer 33 will have a recess 24 where shielding layer 20 is located.
Similarly, recesses within shaped block 4 which are facing upwards and which contain
sections 37a, 37b, 37c of electric lines and which preferably contain also magnetic core
material 39 within a recess 95 in the centre line of block 4, receive material portions 4 1a,
41b and 42 as schematically indicated in the top region of Fig. 3. These material regions
preferable fill all or nearly all remaining gaps between electric line sections 37 or the
magnetic core material 39 and the walls of the recesses.
Fig. 4 shows a perspective view of a shaped block 304 and Fig. 5 shows a top view of the
shaped block 304, which comprises six recesses 3 15a - 3 15f extending perpendicularly toa centre line 310 which divides the block 304 in two halves. The centre line 310 extends in
the direction of travel of a vehicle, if the block 304 forms part of a route for the vehicle.
The recesses 3 15 are parallel to each other and are arranged within the same horizontal
plane which is parallel to the plane of Fig. 5. The recesses 315 extend in width direction
(the vertical direction in Fig. 5) over about three quarters of the total width of block 304.
They are arranged symmetrically to the centre line 310.
Each recess has a U-shaped cross-section to receive a cable. The dashed lines shown in
Fig. 5 which extend along the recesses 315 are centre lines of the recesses 3 15. At each
of the two opposite ends of the straight recesses 3 15, there are bifurcated curved recess
regions 3 16 which form transitions to a peripheral straight recess 3 17 extending along the
lateral edge of the block 304. Cables can be laid in a manner consecutively extending
from the straight recesses 3 15 through the curved recess region 3 16 into the peripheral
straight recess 3 17, thereby changing the direction of extension from perpendicular to the
direction of travel to parallel to the direction of travel. Examples of arrangements of
electric lines (e.g. cables) are shown in Fig. 10 and 11 and will be described later.
The curved recess regions 316 allow for placing a cable, which extends through the
recess 315, in such a manner that it continues to either the left or the right, if viewed in the
straight direction of the recess 3 15. For example, a cable (not shown in Fig. 4 and 5) may
extend through recess 3 15b, may turn to the right - while extending through recess region
316 - and may then extend through the straight recess 317 which extends perpendicularly
to the recesses 315 on the opposite side of curved recess region 316. There are two
peripheral straight recess regions 3 17 on opposite sides of block 304. The cable may then
turn to the right through the recess region 316 at the end of recess 3 15e and may then
extend through recess 3 15e. At the end of recess 3 15e, which is shown in the lower part
of Fig. 5, the cable may again turn left through recess region 316 into the other straight
recess 317. The other recesses 3 15 may be used for two other cables.
As shown in Fig. 6, the depth of the recesses 315, 316, 317 is different. The depth of
recess 315 is sufficient to receive one cable. The depth of the curved recess region 316
increases from the end of recess 315 to recess 3 17 as indicated by a dashed line in Fig.
6. The bottom profile of the curved recess region 316 is not fully shown in Fig. 6, since the
sectional view includes a region 319 of block 304 which is not recessed. Each of thecurved recess regions 316 comprises such an island region 3 19 which is located between
the two curved branches of the curved recess region 316. One of the branches extends
above the plane of Fig. 6 and the other branch extends below the plane of Fig. 6. In
addition, the island region 3 19 is located between the straight recess 3 17 and the two
branches of the curved recess region 3 16.
Since the depth of the curved recess region 3 16 increases towards the straight recess
317, different cables can be laid upon one another. The depth of the straight recess 3 17 is
sufficient to arrange two cables upon one another extending in the same straight direction.
For example, a first cable may extend trough the lower recess 3 17 in Fig. 5 and may turn
left into recess 3 15b through the recess region 316 shown in the bottom left part of Fig. 5.
In addition, a second cable may extend trough recess 3 15a, may turn into the recess 317,
thereby crossing (if viewed from above) the first cable.
The example concerning the extension of cables or electric lines given above refers to
one specific application for laying three meandering cables. However, the use of the
shaped block 304 shown in Fig. 4 to 6 is not restricted to this application. Rather, for
example, less or more than three cables can be laid using the block 304 shown in Fig. 5
and 6.
The side surfaces of block 304 shown in Fig. 4 comprise recesses, in particular bores,
290a, 290b, 292a, 292b, 292 c . Other recesses are located at the side surfaces which are
not visible in Fig. 4. In the example shown, the side surface which extends in the direction
of travel (on the right hand side in Fig. 4) comprises three recesses 292a, 292b, 292c. All
recesses 292 contain an anchor 294a, 294c, wherein the anchor or recess 292b is not
shown. The anchors 294 extend as projections from the side surface. When the cover
layer is provided to fill the regions sideways of 304, the anchors 294 are embedded by the
material of the cover layer.
The recesses 290a, 290b of the side surface which faces in the direction of travel also
comprise anchors 291 , wherein the anchor of recess 290a is not shown in Fig. 4. These
anchors are fixed within the recesses 290 before the neighbouring block (not shown in
Fig. 4) is placed near the side surface. The neighbouring block is moved towards the side
surface of block 304 so that the anchors 291 are inserted in corresponding recesses of
the neighbouring block. Then, or immediately before, filling material is introduced in thecorresponding recesses of the neighbouring block in order to fill gaps between the
anchors 291 and the corresponding recesses. The filling material may be a two-
component adhesive.
Fig. 7 shows a cross-section through the construction of a track for a rail vehicle. Fig. 8
shows an exploded cross-sectional view through a modified construction of a track for a
rail vehicle. In both figures, the two rails extending in parallel to each other are denoted by
303a, 303b. In between the rails 303, a block 304 is placed for receiving cables. The block
304 may be the pre-fabricated shaped block of Fig. 4. The embodiments shown in Fig. 7
and 8 differ with respect to a base layer 10 which is rectangular in Fig. 8 and is U-shaped
in Fig. 7. In addition, Fig. 7 shows the underground 35. Furthermore, Fig. 7 shows two
parts of the ground 12 on both sides of the track. Common parts and elements of the
route construction according to Fig. 7 and 8 will be described in the following using the
same reference numerals. Differences, for example with respect to the magnetic core, will
be emphasized.
For preparing the placement of a pre-fabricated track module (consisting of an plurality of
elements), the underground comprises a base layer 10 of concrete. In addition, on both
opposite sides of the base layer 10, conduits 361 are laid (shown only in Fig. 8). In
particular, these conduits 361 are used to place electric connection cables for connecting
electric and electronic devices of the track module. These cables are parts of a power
supply line, for example connecting inverters located sideways of the track in a cavity.
All other parts shown in Fig. 8, are parts of the pre-fabricated track module, except for a
brick layer 340 which is laid on the top surface of the pre-fabricated track module. The
brick layer 340 extends on both sides of the central region of the pre-fabricated track
module where the rails 303 and other parts are located. The brick layer 340 serves to form
a nearly horizontally extending surface of the track construction (see Fig. 7). Instead of a
brick layer, the gap between the ground 12 and the central part of the track module can be
filled by another material, such as concrete.
The embodiment of the track module, which is shown in Fig. 8 and 7 comprises a U-
shaped bottom layer 15, preferably made of concrete. Any kind of concrete material may
be used, such as conventional concrete, concrete comprising plastic material and fibre
reinforced concrete. Especially, the concrete may be armed by conventional metalmeshes. However, it is preferred to use light weight concrete comprising fibre particles for
reinforcement and comprising plastic elements. Such a concrete material has the further
advantage that vibrations caused by any rail vehicle travelling on the track are attenuated.
The U-shaped bottom layer 15 defines the central region of the track module which is
located in the cut-out area in between the two arms of the U. This central cut-out area is
open to the top and comprises from bottom to top a layer 345 made of elastomeric
material for further damping of vibrations, a shielding element 355, a support element 304
for supporting the conductor arrangement (not shown in Fig. 8 and 7) and a cover 351
made of rubber.
The layer 345 extends in horizontal direction over the whole length of the central region of
the track module. In the regions of the side margins of the central regions, the two rails
303a, 303b are placed on top of the layer 345. As principally known in the art, the rails
303 are held in place using inner and outer fixing elements 335, 336, preferably made of
plastic material, such as polyurethane. The support element 304 comprises recesses 315,
317 and may be constructed as shown in Fig. 1 to 5. The support element 304 is fitted
tightly in between the inner fixing elements 336.
Below the support element 304, the shield 355 for shielding electromagnetic fields
generated by the conductor arrangement extends between the shoes 299a, 299b, thereby
electrically contacting the shoes 336. In an alternative embodiment, the shield may be
connected to just one of the rails. This embodiment is used if the track is combined with a
vehicle detection system using the effect that the vehicle is electrically connecting the two
rails.
The cover 351 extends between the upper parts of the two rails 303 and is mechanical
fixed by protruding downwardly into the grooves between the support element 304 and the
rail 303. Other than shown in Fig. 8, the pre-fabricated track module, comprising the parts
15, 345, 355, 335, 336, 304 and 351 (and optionally comprising further parts, such as the
conductor arrangement) is manufactured first and then positioned on top of the base layer
10. However, the different parts of the track module can be removed on site, for example
the cover 351 for placing the conductor arrangement into the recesses 315, 3 17. After
laying the conductor arrangement, the cover can be put in place again. As mentioned
before, the conductor arrangement can alternatively be part of the pre-fabricated trackmodule so that there is no need to remove the cover 351 , except for maintenance and
repair.
Preferably, the conductor arrangement is placed within the recesses of the support
element in such a manner that the lines or wires of the conductor arrangement do not
protrude above the height level of the edges of the recesses. Therefore, the cover having
a nearly planar surface pointing to the support element can rest on the maximum possible
upper surface of the support element.
The construction shown in Fig. 7 comprises a recess 339 on the underside of an
intermediate layer 341 , which is placed between the shield 355 and the shaped module
304. In contrast to the construction shown in Fig. 8, the shaped module 304 of Fig. 7 does
not extend to the shield 355, but is separated from the shield 355 by the intermediate
layer 341 .
Alternatively to the construction shown in Fig. 7, the recess 339 may be located on the
upper side of the intermediate layer 341 and/or may be located on the underside of the
shaped module 304, similar to the construction shown in Fig. 8. However, the shaped
module 304 of Fig. 8 extends in vertical direction to the shield 355, i.e. there is no
intermediate layer between the shaped module 304 and the shield 355. The recess for the
magnetic core in the construction shown in Fig. 8 is denoted by reference numeral 349.
The recesses 339, 349 shown in Figures 7 and 8 extend in the direction of travel which is
perpendicular to the image plane of the Figures. At least part of the recess 339, 349 with
respect to the vertical direction is filled with magnetic core material (not shown in Figures
7 and 8), similarly to the schematic view shown in Fig. 12. However, the Fig. 1 shows a
variant in which the recess 439 is provided on the upper side of a shaped block or
material layer 404 and is, therefore, open to the top. During construction of the route, the
recess 439 will be filled with magnetic core material 39 up to a certain, pre-defined height
and then the line or lines of the primary side conductor arrangement are laid. One line
section 407 which extends transversely to the direction of travel (the direction of travel is
perpendicular to the image plane of Fig. 12) is shown in Fig. 12. The shield (not shown in
Fig. 12) may be located at the bottom surface of the shaped module or material layer 404
or may be located further below.In the embodiment shown in Fig. 7, the shield 355 is laid first and then the pre-fabricated
intermediate layer 341 , which already includes the magnetic core material within the
recess 339, is placed on top of the shield 355. For example, the magnetic core material
may be fixed to the intermediate layer module 341 using adhesive. Alternatively, the
magnetic core material may be placed first on top of the shield 355 and then the
intermediate layer 341 may be produced from non-solid raw material, such as concrete.
The production of the magnetic core in the construction shown in Fig. 8 may be performed
in the same manner as explained before for the construction shown in Fig. 7. However,
there is no intermediate layer in Fig. 8 so that the magnetic core material is either fixed to
the shaped module 304 before placing the shaped module 304 on top of the shield 355 or
is placed first on top of the shield 355, before placing the shaped module 304 on top of the
arrangement.
Fig. 9 shows six segments 157a to 157f of a conductor arrangement which extend along a
path of travel (from right to left or vice versa) of a vehicle (not shown). The segments 157
can be operated independently of each other. They are electrically connected in parallel to
each other. The vehicle may comprise a receiving device for receiving the electromagnetic
field produced by one or more than one of the segments 157. If, for example, the receiving
device of the vehicle is located above segment 157c at least this segment 157c is
operated to produce an electromagnetic field and to provide energy to the vehicle.
Furthermore, the vehicle may comprise energy storages which may be used to operate
the vehicle if not sufficient energy is received from the segments 157.
At each interface between two consecutive segments 157, an inverter 152a to 152e is
provided which is placed within a cavity, preferably within the ground sideways of the
route. A DC (direct current) power supply line 141a, 141b is also shown in Fig. 9. It is
connected to an energy source 15 1, such as a power station for producing a direct
current.
Fig. 10 schematically shows by dashed lines the outer limits 504 of a track or part of a
track which may be defined by shaped blocks 304 of the kind shown in Fig. 4, with the
exception that there is an area 609 for conducting lines to and/or from the track. For
example, the area 609 may be located in a cut-out 341 at one side of the block. Such acut-out facilitates completing the conductor arrangement made of electric lines which are
held by the blocks in place.
The conductor arrangement shown in Fig. 10 is a three-phase conductor arrangement, i.e.
each of the two segments of the conductor arrangement shown in Fig. 10 comprises three
phase lines 507a, 507b, 507c; 508a, 508b, 508c for conducting three phases of a three
phase alternating electric current. One of the three phases 507a, 508a is indicated by a
single line, the second of the three phases 507b, 508b is indicated by a double line and
the third of the three phases 507c, 508c is indicated by a triple line. All electric lines are
extending in a meandering manner in the direction of travel (from left to right or vice
versa). The region shown in Fig. 10 is a transition region of two consecutive segments of
the conductor arrangement. Each segment can be operated separately of each other, but
the segments can also be operated simultaneously. Fig. 10 shows a preferred
embodiment of a basic concept, namely the concept of overlapping regions of the
consecutive segments. Preferably the shield (not shown, e.g. located in parallel to the
image plane of Fig. 10) covers the area delimited by the dashed lines 504, the area 609
and the area where the lines 507, 508 are conducted to devices sideways of the track or
route.
The meandering three-phase conductor arrangement, which is described in the following
can also be realised, if the connection to external devices is made in a different manner.
The segment shown on the left hand side in Fig. 10 comprises phase lines 507a, 507b,
507c. Following the extension of these phase lines 507, from left to right, each phase line
507 which reaches the cut-out area 609 is conducted away from the consecutive line of
shaped blocks towards any device (not shown) for operating the phase lines 507. For
example, phase line 507b reaches cut-out 609 where the cut-out 609 ends. In contrast to
phase line 507b, phase lines 507a, 507c reach the cut-out 609 with a line section which
extends from the opposite side of the line of shaped blocks towards the cut-out 609.
The three phase lines 507 each comprise line sections which extend transversely to the
direction of travel. These transversely extending sections form a repeating sequence of
phases in the direction of travel, i.e. a section of the first phase line 507a is followed by a
section of the second phase line 507b which is followed by a line section of the third
phase line 507c and so on. In order to continue with this repeated sequence of the phase
lines, a phase line 508b (the second phase line) of the neighbouring segment isconducted through the cut-out area 609 so that it forms a transversely extending line
section in between the first phase line 507a and the third phase line 507c of the other
segment where they reach the area 609. In other words, the second phase line 508b of
the second segment replaces the second phase line 507b of the first segment in order to
continue with the repeated sequence of phase lines. The other phase lines of the second
segment, namely the first phase line 508a and the third phase line 508c are conducted
through cut-out area 609 in a corresponding manner so that the sequence of phases, if
the extension in the direction of travel is considered, is the same as for the first segment
on the left hand side of Fig. 10.
Fig. 11 shows a similar arrangement, in which the area 609 is used for a different
purpose. Same reference numerals in Fig. 10 and Fig. 11 refer to the same features and
elements.
Fig. 11 shows the transition region of two consecutive segments, for example the segment
shown on the right hand side in Fig. 10 and a further segment of the conductor
arrangement. The phase lines of this further segment are denoted by 509a (first phase
line), 509b (second phase line) and 509c (third phase line) of the further segment. In the
embodiment shown in Fig. 11, the cut-out 609 is used as an area for establishing electric
connections between the three phases of each segment, i.e. a star point connection is
made for each segment. The star points are denoted by 5 1 1a or 5 11b. Preferably, the
location of the star point 5 11 is at a greater distance to the upper surface of the cover
layer than the line sections of the phase lines where the phase lines are located within the
recesses or spaces which are defined by the shaped blocks. Therefore, the star point
connections are well protected.
Figures13 to 15 show a schematic side of view of a system for inductively transferring
energy to a vehicle, including the primary side and the secondary side electric lines. The
primary side lines are shown as small rectangles 501a - 501 o. These rectangles
symbolise cross sections of transversely extending line sections of the electric lines of a
three-phase conductor arrangement, for example of the arrangement shown in Figures 10
and 11. These transversely extending line sections 501 produce the alternating
electromagnetic field, and produce in particular a magnetic wave which moves into the
travel direction or opposite to the travel direction. The travel direction extends from left to
right or from right to left in Figures 13 to 15.At a higher position in Figures 13 to 15, the conductors of the secondary side
arrangement of the vehicle are shown and denoted by 502a - 502i. These secondary side
conductors also extend transversely to the direction of travel. On top of the secondary
side conductors 502, there is a layer of magnetic core material 510. However, the height
of the core 510 is not drawn to scale in order show the course of magnetic flux lines. The
same applies to the magnetic cores 5 10, 530 in Fig. 14 and Fig. 15. All these magnetic
cores are preferably smaller in vertical direction compared to the vertical extension of the
primary side and secondary side conductors and the vertical distances between these
conductors.
Figures 13 to 15 also show the magnetic flux lines (i.e. field lines of the magnetic field
which is produced by the primary side conductors 501 for three different configurations
and/or locations of the cross sections shown in the figures.
Fig. 13 shows a configuration in which there is no shield of electrically conductive material
below the primary side conductors 501 and in which there is no magnetic core material
below or at the primary side conductors 501 . Consequently, the flux lines deeply penetrate
in areas below the primary side conductor arrangement.
Fig. 14 shows a configuration in which there is a shield 520 of electrically conductive
material below the primary side conductors 501 . The shield 520 almost completely
prevents the penetration of magnetic field lines through the shield 520. As a result, the
field lines are diverted above the shield 520 so that they extend nearly horizontally
between the shield 520 and secondary side conductor arrangement 502. However, due to
energy losses caused by eddy currents within the shield 520, the magnetic flux at the
secondary side conductor arrangement is reduced.
The configuration shown in Fig. 15 comprises a layer or line of magnetic core material 530
instead of the shield 520 of the configuration shown in Fig. 14. The vertical position of the
magnetic core material 530 is slightly higher than the vertical position of the shield 520 in
Fig. 14.
The effect of the magnetic core material 530 is that the magnetic field lines are attracted,
i.e. extend nearly perpendicularly to the magnetic core material 530, but are re-directed bythe magnetic core material 530 to follow the horizontal extension of the layer or line.
Furthermore, the magnetic core material 530 increases the magnetic flux at the secondary
side conductor arrangement.
Coming back to the configuration shown in Fig. 12, provided that there is an additional
shield below the magnetic core material 39 extending horizontally, i.e. parallel to the
transversely extending line section 407, the configuration shown in Fig. 15 corresponds to
the cross section indicated by a dashed line XIV in Fig. 1 . I.e. the cross section shown in
Fig. 14 would extend perpendicularly to the image plane of Fig. 12 at the dashed line XIV.
Similarly, the cross section shown in Fig. 15 would extend perpendicularly to the image
plane of Fig. 12 at the dashed line XV which intersects the magnetic core 39. This means
that the configuration shown in Fig. 14 and the resulting magnetic flux lines shown in Fig.
14 represent the situation approximately in the area of dashed line XIV in Fig. 12 and that
the configuration and magnetic flux lines shown in Fig. 15 represent the situation at the
dash line XV in Fig. 12. The reason why the shield of electrically conducting material has
no influence on the situation shown in Fig. 15 is that the magnetic core material attracts
and redirects the magnetic flux lines. However, due to the small thickness of the magnetic
core material, a comparatively small magnetic flux is effective even immediately below the
magnetic core material as shown in Fig. 15 by one magnetic flux line below the magnetic
core material 530.
If the induction which is caused by the magnetic field in the secondary side conductor
arrangement is integrated over the length of transversely extending line sections (i.e. from
left to right in Fig. 12, the total induction and the resulting electric current may correspond
to the corresponding situation without shield and magnetic core at the primary side, if the
magnetic core and the shield are configured appropriately. The shield reduces the
magnetic flux, but shields nearly the full area below the shield, and the magnetic core
material increases the magnetic flux in the central area of the cross section shown in Fig.
12. In other words: the shield helps to reduce the required amount of magnetic core
material and the flux-weakening effect of the shield is compensated by the magnetic core
material.Patent Claims
1. A system for transferring electric energy to a vehicle, in particular to a road
automobile or to a track bound vehicle such as a light rail vehicle, wherein the
system comprises an electric conductor arrangement (7) for producing a magnetic
field and for thereby transferring the energy to the vehicle, wherein the electric
conductor arrangement (7) comprises at least one current line (507, 508, 509),
wherein each current line (507, 508, 509) is adapted to carry the electric current
which produces the magnetic field or is adapted to carry one of parallel electric
currents which produce the magnetic field and wherein:
- the current line or lines (507, 508, 509) extend(s) at a first height level,
- the system comprises an electrically conductive shield (20; 355; 520) for
shielding the magnetic field, wherein the shield (20; 355; 520) extends
under the track and extends below the first height level, and
- a magnetic core (39) extends along the track at a second height level and
extends above the shield (20; 355; 520).
2. The system of claim 1, wherein the second height level at which the magnetic core
(39) extends is below the first height level and wherein the magnetic core (39)
extends between the shield (20; 355; 520) and the current line or lines (507, 508,
509)
3. The system of claim 1 or 2, wherein the magnetic core (39) extends in the direction
of travel.
4. The system of one of the preceding claims, wherein the material of the magnetic
core (39) is placed in grooves and/or recesses of pre-fabricated modules adapted
to carry the material and to fix the current line or lines.
5. The system of one of the preceding claims, wherein the current line or lines (507,
508, 509) comprise(s) a plurality of line sections (407) extending transversely to
the direction of travel at the first height level.
6. A method of building a system for transferring electric energy to a vehicle (81 ; 92),
in particular to a road automobile or to a track bound vehicle such as a light railvehicle, wherein an electric conductor arrangement (7) for producing a magnetic
field and for thereby transferring the energy to the vehicle (81 ; 92) is provided,
wherein at least one current line (507, 508, 509) is provided for the electric
conductor arrangement (7), each current line (507, 508, 509) being adapted to
carry the electric current which produces the magnetic field or is adapted to carry
one of parallel electric currents which produce the magnetic field and wherein:
- the current line or lines (507, 508, 509) is/are arranged to extend at a first
height level,
- an electrically conductive shield (20; 355; 520) is provided for shielding the
magnetic field, wherein the shield (20; 355; 520) is arranged so that it
extends under the track and so that it extends below the first height level,
and
- a magnetic core (39) is provided so that it extends along the track at a
second height level and so that it extends above the shield (20; 355; 520).
7. The method of claim 6, wherein the second height level at which the magnetic core
(39) extends is below the first height level and wherein the magnetic core (39) is
provided so that it extends between the shield (20; 355; 520) and the current line
or lines (507, 508, 509)
8. The method of claim 6 or 7, wherein the magnetic core (39) is provided so that it
extends in the direction of travel.
9. The method of one of claims 6 - 8, wherein the material of the magnetic core (39)
is placed in grooves and/or recesses of pre-fabricated modules so that the
modules carry the material and wherein the current line or lines is/are fixed by the
modules.
10. The method of one of claims 6 - 9, wherein the current line or lines (507, 508, 509)
is/are arranged so that it/they comprise(s) a plurality of line sections extending
transversely to the direction of travel at the first height level.