Note: Descriptions are shown in the official language in which they were submitted.
CA 02639155 2008-08-28
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Apparatus and method for wireless energy and/or data
transmission between a source device and at least one
target device
The invention relates to an apparatus and a method for
wireless energy and/or data transmission between a
source device and at least one target device, in which
apparatus and method at least one primary circuit with
at least one primary coil, on the source-device side,
and at least one secondary circuit with at least one
secondary coil, on the target-device side, are
provided. In particular, the invention relates to
inductive energy transmission between devices or device
components for the purpose of charging at least one
rechargeable battery arranged in a device or in a
device component, such as for the purpose of charging a
rechargeable battery in a remote control, for example.
For medical devices, in particular for operating
tables, remote controls are available as wireless
operating devices, with the aid of which the respective
device can be operated from various positions and at a
certain distance from a receiver unit of the device for
receiving the signals from the remote control. Such
remote controls make convenient use of at least some of
the operating functions of the medical device or of the
operating table possible. Such operating devices are
operated by batteries or rechargeable batteries in the
prior art. In order to ensure ease of use of such a
remote control, it is recommended to use rechargeable
batteries, as a result of which the remote control can
be used as the operating unit throughout subsequent
treatment once the rechargeable batteries have been
charged or recharged.
In addition, the use of special rechargeable batteries
makes it possible to provide a large quantity of energy
for operation of the remote control in the case of a
relatively small physical size which is matched to the
CA 02639155 2008-08-28
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design-related conditions of the remote control. In
order to charge the -rechargeable batteries, a
connection to a further energy source, in particular to
a suitable switched-mode power supply or to a charger,
needs to be produced. For this purpose, both
arrangements with a DC connection between the charger
and the rechargeable battery and without a DC
connection between the charger and the rechargeable
battery are known in the prior art. In the case of the
known arrangements in which there is no DC connection
between the remote control and the energy source (i.e.
in the case of DC isolation), the energy transmission
generally takes place inductively between a charging
station or base station and the remote control. The
charging station or the base station is in this case
the source device and the remote control is the target
device.
Figure 1 illustrates a known arrangement 10 for the
inductive transmission of energy. The arrangement 10 in
this case comprises a source device 12 and a target
device 14. The source device 12 comprises an energy
source 16, which is in the form of an AC source and
generates an AC voltage. In addition, the source device
12 comprises a coil 18 on the source-device side which
acts as a primary coil 18 for energy or data
transmission to the target device 14. The target device
14 comprises a coil 20 on the target-device side which
acts as a secondary coil 20 and is electrically
connected to a charging circuit 22, which is
illustrated as a load resistor. The energy source 16 of
the source device 12 is electrically connected to the
primary coil 18 on the source-device side, with the
result that the energy source 16 brings about an
alternating current flow through the coil 18, as a
result of which the coil 18 generates a magnetic field
which changes over time (alternating magnetic field).
The secondary coil 20 on the target-device side is
located in the magnetic field induced by the primary
CA 02639155 2008-08-28
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coil 18 if the target device 14 is located in a
charging and/or data transmission position. A voltage
is induced in the secondary coil 20 by means of the
alternating magnetic field, and, as a result of this
voltage, a current flow through the charging circuit
22, which is illustrated as a load resistor, is
possible, with the result that the energy transmitted
from the energy source 16 via the coils 18, 20 is
supplied to this charging circuit 22. As an alternative
or in addition to the charging circuit 22, an
evaluation circuit for determining data transmitted via
the arrangement shown in Figure 1 can be provided.
Figure 2 illustrates an arrangement 24 for transmitting
energy between a source device 26 and a target device
28 similar to the arrangement 10 shown in Figure 1.
Identical elements have the same reference symbols. In
contrast to the arrangement 10 shown in Figure 1, the
circuit of the source device 26 and the circuit of the
target device 28 each contain a capacitor 30, 32. A
series resonant circuit is formed by the arrangement of
the capacitor 30 in the circuit of the source device 26
and a parallel resonant circuit is formed by the
capacitor 32 in the secondary circuit. Resonant
coupling takes place between the source device 26 and
the target device 28 by means of these resonant
circuits, and this results in a relatively high
efficiency in the transmission of energy from the
primary circuit to the secondary circuit or from the
source device 26 to the target device 28. In the
arrangement 24 shown in Figure 2, a magnetic field is
induced by the primary coil 18. The primary coil 18 and
the capacitor 30 form a primary circuit which is tuned
to resonance. The magnetic field induced by the primary
coil 18 passes through the secondary coil 20, which is
part of the secondary resonant circuit. However, in
practice it is difficult to match the resonant
frequencies of the primary-side resonant circuit and of
the secondary-side resonant circuit to one another
CA 02639155 2008-08-28
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since the resonance conditions change depending on the
state of charge of the rechargeable batteries or
depending on the resistance value of the load resistor
22, which changes over the charging cycle.
In order to match the resonant frequency, various
measures are conceivable both on the primary side and
on the secondary side. For example, a suitable
frequency of the energy source 16 can be selected, with
it being possible for the frequency to be preset, set
in a predetermined frequency range, regulated or
corrected. Furthermore, suitable design measures, in
particular mechanical and electronic measures, can be
provided in order to maintain the resonance conditions
over a relatively long charging cycle. In particular,
maintenance of the resonance condition can be achieved
or at least assisted by a suitable selection of
components. In addition, resonance adjustment can be
achieved by changing the capacitance of at least one of
the capacitors 30, 32 or the inductance of at least one
of the coils 18, 20. However, this is associated with a
relatively high level complexity. Overall, maintenance
of the resonance conditions in the primary and/or
secondary circuit is relatively complex.
Figure 3 illustrates an arrangement 34 for transmitting
energy between a source device 36 and a target device
38 similar to the arrangement 10 shown in Figure 1. In
contrast to the arrangement 10 shown in Figure 1, the
primary coil 18 is arranged around a first iron core
segment 40 and the secondary coil 20 is arranged around
a second iron core segment 42. The iron core segments
40, 42 have a gap 44 on their mutually facing end sides
in a charging and/or data transmission position. The
gap 44 is in particular formed by the respectively
closed housings of the source device 36 and of the
target device 38 and/or by an additional air gap. The
lines of force emerging from one of the end sides,
which are remote from one another, of the magnet core
CA 02639155 2008-08-28
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segments 40, 42 enter the opposite remote end side and
close the magnetic circuit with the magnet core
segments 40, 42 and with the gap 44.
Figure 4 shows an arrangement 46 similar to the
arrangement 34 shown in Figure 3, with, both in the
case of the source device 48 and in the case of the
target device 50, magnet core segments 52, 54 being
inserted which are u-shaped and are arranged in a data
and/or energy transmission position in such a way that
in each case both end faces of the magnet core segments
52, 54 are opposite one another and are arranged at a
distance from one another in such a way that in each
case a gap 56, 58 similar to the gap 44 in the
arrangement 34 is provided between these end sides.
Figure 5 illustrates an arrangement 60 similar to the
arrangement 46 shown in Figure 4, with in each case one
capacitor 30, 32 being provided in the circuit of the
source device 62 and in the circuit of the target
device 64 so as to form resonant circuits in the same
way as already described in connection with Figure 2.
In general, the housings of the source devices and of
the target devices are made from electrically
insulating material which does not weaken
electromagnetic fields or weakens them only to a small
extent. As a result of the minimum thicknesses required
for the housing walls, in particular for the electrical
insulation and mechanical strength of the housing of
the source device and of the target device, the gap or
gaps has or have a minimum gap width in the known
embodiments shown which substantially influences the
properties of the magnetic circuit. The gap width is
critical for the magnetic field strength in the
magnetic circuit, formed by the magnet core segments,
of the arrangement shown in Figures 1 to 5.
CA 02639155 2008-08-28
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The document DE 38 10 702 C2 has disclosed an
arrangement in which a frequency correction of an
energy source is carried out. For this purpose, in this
arrangement the phase relationship between the current
and the voltage in the primary circuit is determined
and regulated to a preset value.
The document DE 198 37 675 Al has disclosed a charging
apparatus in which a power oscillator is provided in a
primary part of an inductive coupler for the inductive
transmission of charging energy. A switching apparatus
for alternately drawing power for charging the
rechargeable battery is provided in the secondary part.
The document DE 601 02 613 T2 has disclosed an
arrangement in which the transmission power of the
energy output by a transponder read apparatus is set.
In this case, a series resonant circuit is provided in
the primary-side or transmitter-side circuit for
providing the transmission power. Up-to-date
information on the magnetic coupling between a
transponder and the read apparatus is detected. The
resonant circuit has a variable capacitance, by means
of which the resonant circuit can be tuned.
Against the background of the arrangements known in the
prior art, the invention is based. on the object of
specifying an apparatus and a method for wireless
energy and/or data transmission between a source device
and at least one target device, in which apparatus and
method effective energy and data transmission is
possible alongside a simple design.
This object is achieved by an apparatus having the
features of Patent Claim 1 and by a method having the
features of the independent method claim. Advantageous
developments of the invention are specified in the
dependent patent claims.
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As a result of an apparatus according to the invention
and a method according to the invention for wireless
energy and/or.data transmission between a source device
and at least one target device, the resonant frequency
of the resonator and the fulfilment of the resonance
condition do not need to be dependent on the varying
conditions of the primary circuit and of the secondary
circuit. In particular, the resonator is independent of
the variable load in the secondary circuit. As a result
of the resonator, which is electrically isolated from
the primary circuit and from the secondary circuit, in
addition targeted efficient energy transmission between
the primary circuit and the secondary circuit can take
place. In the case of the arrangement of a plurality of
resonators, which are each electrically isolated from
the primary circuit and from the secondary circuit,
with different resonant frequencies, virtually any
desired signal forms can be transmitted, such as, for
example, square-wave signals which comprise, for
example, a plurality of harmonic oscillations.- Each
resonator is in this case preferably formed by a
resonant circuit, which comprises in particular at
least one inductance and a capacitance.
Energy is then transmitted from the primary side to the
secondary side by each of the resonant circuits, as a
result of which the total quantity of energy
transmitted is the sum of the energy component
transmitted directly from the primary circuit to the
secondary circuit and the energy component transmitted
from the primary circuit to the resonant circuits and
from the resonant circuits to the secondary circuit.
For example, the total quantity of energy transmitted
can be increased by approximately 15% if two resonators
are provided instead of one. The second resonator
preferably has twice the resonant frequency of the
first resonator. For the invention, however, instead of
an electromagnetic resonator, other resonators, such as
acoustic, mechanical or hydromechanical resonators, can
CA 02639155 2008-08-28
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also be used. A resonator within the meaning of the
invention is in this case any oscillatory system whose
components are tuned to an input frequency in such a
way that the resonator decays on excitation at this
frequency.
In a development of the invention, the resonator is in
the form of a resonant circuit or the resonators are in
the form of resonant circuits. The primary coil, the
secondary coil and the inductance of the isolated
resonant circuit/the isolated resonant circuits are in
this case preferably arranged in the same magnetic
circuit. It is advantageous here if the primary coil,
the secondary coil and a coil forming the inductance of
the isolated resonant circuit arearranged around a
magnet core surrounded by the magnetic circuit, the
magnetic circuit preferably having a magnet core
without a gap.
In addition, it is advantageous to provide at least two
resonant circuits which are each electrically isolated
from the secondary circuit and from the respective
other circuit. The inductances of the at least two
resonant circuits are preferably each in the form of a
coil, whose windings are formed as bifilar windings or,
in the case of more than two resonant circuits, as n-
filar windings. As a result of the bifilar windings or,
in the case of n resonant circuits, as a result of the
n-filar windings, the coils formed by these windings
preferably have the same inductance, with the result
that the resonant frequency can be set merely by
selecting different capacitances. This is advantageous
if the resonant circuits have different resonant
frequencies from one another, with the result that the
energy transmission between the primary circuit and the
secondary circuit is influenced by the resonant
circuits with the superimposed resonant frequencies of
the resonant circuits or of the resonators.
CA 02639155 2008-08-28
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It may also be advantageous if the winding of the
secondary coil and the winding of a coil forming the
inductance of the resonant circuit and/or the winding
of the primary coil and the winding of a coil forming
the inductance of the resonant circuit can be formed as
a bifilar winding. If a plurality of resonant circuits
is provided, the windings of the coils of the resonant
circuits or the windings of some of the coils of the
resonant circuit and the primary winding or the
secondary winding can be formed as n-filar windings.
The provision of n-filar windings simplifies the
manufacture of the entire apparatus. In particular, the
inductance of the coils formed by the n-filar windings
can easily be changed, in particular doubled, by a
plurality of coils being interconnected.
In addition, it is advantageous to analyse a signal to
be transmitted with the aid of Fourier transformation.
A resonant circuit is provided for each of the harmonic
oscillations of a signal to be transmitted which has
been analysed by Fourier transformation, the resonant
frequency of said resonant circuit corresponding to the
frequency of the respective harmonic oscillation. As a
result, virtually any desired signal forms can be
formed from the harmonic oscillations, with the result
that, for example, a substantially square-wave signal
profile can be produced on the secondary side, for
example. Reference is made to the fact that the
independent method claim can also be developed with
features of individual dependent apparatus claims or
corresponding method features.
Further features and advantages of the invention are
given in the description below, which, in connection
with the attached figures, explains the invention in
more detail with reference to exemplary embodiments.
In the figures:
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Figure 6 shows an arrangement for the inductive
transmission of energy in accordance with a
first embodiment of the invention;
Figure 7 shows an arrangement for the inductive
transmission of energy in accordance with a
second embodiment of the invention;
Figure 8 shows an arrangement for the inductive
transmission of energy in accordance with a
third embodiment of the invention;
Figure 9 shows an arrangement for the inductive
transmission of energy in accordance with a
fourth embodiment of the invention;
Figure 10 shows an arrangement for the inductive
transmission of energy in accordance with a
fifth embodiment of the invention; and
Figure 11 shows an arrangement for the inductive
transmission of energy in accordance with a
sixth embodiment of the invention.
Figure 6 illustrates an arrangement 100 for wireless
energy and/or data transmission between a source device
102 and a target device 104 in accordance with a first
embodiment of the invention. The arrangement 100 has a
similar design to the known arrangement 46 already
described and shown in Figure 4. Identical elements
have the same reference symbols. In addition to the
primary-side circuit, which comprises the energy source
16 and the coil 18, the arrangement 100 also has the
secondary-side circuit with the secondary coil 20 and
with the charging circuit 22 illustrated as a load
resistor. The magnet or iron core comprises a first
primary-side u-shaped magnet core segment 52, around
which the windings of the primary coil 18 are arranged,
and a- second secondary-side u-shaped magnet core
CA 02639155 2008-08-28
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segment 54. The gaps 56, 58 are provided between the
magnet core segments 52, 54 in a charging and/or data
transmission position of the source device 102 and of
the target device 104. In addition, the arrangement 100
has a coil 106, whose windings are arranged around the
second magnet core segment 54 and which is electrically
connected to a capacitor 108. The coil 106 and the
capacitor 108 form a resonant circuit, which has a
resonant frequency which is dependent on the inductance
of the coil 106 and on the capacitance of the capacitor
108. This resonant circuit is a resonator within the
meaning of the invention. In the arrangement 100 shown
in Figure 6, the resonator is therefore arranged on the
secondary side, i.e. in the target device 104.
Figure 7 illustrates an arrangement 110 for wireless
energy and/or data transmission between a source device
112 and a target device 114 in accordance with a second
embodiment of the invention. The arrangement 110 has a
similar design to the arrangement 100 shown in Figure
6. In contrast to the arrangement 100 shown in Figure
6, the resonator comprising the coil 106 and the
capacitor 108 is arranged physically in the source
device 112, with the windings of the coil 106 being
arranged around the first magnet core segment 52 of the
magnet core.
Figure 8 illustrates an arrangement 120 for wireless
energy and/or wire transmission between a source device
122 and a target device 124 in accordance with a third
embodiment of the invention, in which both a primary-
side resonator and a secondary-side resonator are
provided. A coil 126 and a capacitor 128 are
electrically connected to one another and form the
secondary-side resonator. A coil 130 and a capacitor
132 are electrically connected to one another to form a
circuit and form the primary-side resonator. The
windings of the coil 130 and of the primary coil 18 on
the source-device side are formed as bifilar windings.
CA 02639155 2008-08-28
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In the same way, the windings of the coil 126 and of
the secondary coil 20 on the target-device side are
formed as a bifilar windihg.
Figure 9 illustrates an arrangement 140 similar to the
arrangement 120 shown in Figure 8 for wireless energy
and/or data transmission between a source device 142
and at least one target device 144 in accordance with a
fourth embodiment of the invention, in which the
windings of the primary coil 18 on the source-device
side and of the coil 130 of the primary-side resonator
are formed as separate windings. In the same way, the
windings of the secondary coil 20 on the target-device
side and the coil 126 of the secondary-side resonator
are formed as separate windings.
Figure 10 illustrates an arrangement 150 for wireless
energy and/or data transmission between a source device
152 and a target device 154 in accordance with a fifth
embodiment of the invention which has a resonator on
the target-device side. The windings of the coil of the
resonator on the target-device side and the secondary
coil on the target-device side are formed as bifilar
windings in this embodiment. A primary-side resonator
is not provided in this embodiment.
Figure 11 illustrates an arrangement 160 for wireless
energy and/or data transmission between a source device
162 and a target device 164 in accordance with a sixth
embodiment of the invention. The arrangement has a
primary-side resonator. The windings of the coil 130 of
the resonator are formed as a bifilar winding with the
windings of the primary coil 18 on the source-device
side.
The embodiments of the invention described show, in the
case of the formations of the winding of the coils of
the resonators, either the use of bifilar windings with
the primary coil 18 on the source-device side or with
CA 02639155 2008-08-28
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the windings of the secondary coil 20 on the target-
device side or the formation of separate windings of
the primary coil on the source-device side and of the
coil of the resonator and a separate arrangement of the
secondary coil 20 on the target-device side and of the
coil of the resonator or the coils of the resonators.
However, in the same way arrangements are possible in
which, for example, the windings of a primary-side
resonator and the windings of the primary coil 18 on
the source-device,side are formed as separate windings
and the windings of a coil of a secondary-side
resonator and windings of the secondary coil 20 on the
target-device side are formed as separate windings. In
the same way, it is possible to form the windings of
the coil of a primary-side resonator and the primary
coil 18 on the source-device side as separate windings
and to form the windings of the coil of a secondary-
side resonator and secondary coil 20 on the target-
device side as a bifilar winding. For the purposes of a
simplified illustration, in the exemplary embodiments
in each case only one resonator is illustrated both on
the primary side and on the secondary side. However, it
is expedient to provide a plurality of primary-side
and/or a plurality of. secondary-side resonators in
certain embodiments of the invention, with the windings
of said resonators preferably being formed as n-filar
windings with the primary coil 18 or secondary coil 20
and/or as separate windings from the windings of the
primary coil 18 and the secondary coil 20.
If a plurality of resonators are provided, they
preferably have different resonant frequencies. In this
case it is advantageous to form the coils of all
secondary-side resonators and the windings of the coils
of all primary-side resonators in each case as n-filar
windings, with the result that they in each case have
substantially the same inductance. As a result of the
n-filar windings, a substantially corresponding
inductance of the coils wound in this way can be made
CA 02639155 2008-08-28
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possible in a simple manner in the production process.
By means of interconnecting a plurality of coils, the
inductance can be precisely multiplied. In order to fix
the desired resonant frequency, capacitors with a'
suitable capacitance are then provided, which are each
electrically connected to a coil or to a plurality of
interconnected coils and therefore form a resonant
circuit (resonator). By providing resonators which are
not electrically connected to, i.e. electrically
isolated from, the primary circuit and the secondary
circuit, a high degree of efficiency for the energy and
data transmission is achieved. Component tolerances of
the components contained in the primary circuit and the
secondary circuit and a change in the properties of the
load resistor formed by the charging circuit 22 in this
case do not result in a change in the properties of the
resonator, in particular do not result in a change in
the resonant frequency. A complex adjustment or
correction of the resonant frequency is therefore not
necessary as a result of the invention.
As shown in the exemplary embodiments, it is
advantageous to arrange the at least one resonator in
the same magnetic circuit as the primary coil and the
secondary coil 20. When a plurality of resonators are
used, resonant transmission of radiofrequency, non-
sinusoidal signals which preferably comprise a
plurality of sinusoidal harmonic oscillations can take
place. As a result, in particular substantially square-
wave signals can be transmitted in a simple manner. The
arrangements according to the invention are shown, by
way of example, with two u-shaped magnet core segments
52, 54. However, other core shapes of the invention can
also be used in the same way. In particular, it is also
possible for only one primary-side magnet core to be
provided, which magnet core is designed in terms of
construction in such a way that it projects
mechanically out of the source device. A cutout is then
preferably provided in the housing of the target
CA 02639155 2008-08-28
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device, into which cutout the projecting magnet core
protrudes in a charging position and/or in a data
transmission position. The secondary coil 20 is
arranged around the cutout, with the result that said
secondary coil is arranged around the magnet core if
the source device and the target device are located in
a data transmission position or energy transmission
position. Alternatively or in addition, the target
device can have a projecting core region, which
protrudes into a cutout of the source device if the
source device and the target device are located in a
data transmission position or energy transmission
position. Then, the primary coil is arranged around the
cutout of the source device. Preferably, the housing of
the source device or target device is formed around the
projecting magnet core and along the cutout, with the
result that at least the target device has a
circumferentially closed housing.
The energy transmission between the primary side on the
source-device side and the secondary side on the
target-device side is substantially dependent on the
intensity of the magnetic field induced by the primary
coil or the magnetic flux in the magnetic circuit and
the frequency of the AC voltage generated by the energy
source 16. Owing to the resonant circuits, in
particular magnification of the current and/or voltage
due to resonance may take place. A bar-shaped formation
of the magnet core, as is shown in connection with
Figure 2, can lead to problems with EMC owing to the
relatively free propagation possibilities of the lines
of force of the magnetic field in the outer region. In
addition, the field strength or the magnetic flux can
only be increased with a relatively large degree of
complexity. The quantity of energy transmitted to the
secondary side depends on the magnetic field strength
and the frequi~ncy at which the magnetic field strength
changes. A voltage is induced in the secondary coil 20
CA 02639155 2008-08-28
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as a result of the change in the field strength of the
magnetic field induced by the primary coil.
According to the invention, a primary-side circuit with
a primary-side coil, a secondary-side circuit with a
secondary-side coil and a resonator, which is
additionally arranged in the magnetic circuit or in the
region of the magnetic field induced by the primary
coil, are used in order to make wireless energy
transmission or data transmission between the primary
side and the secondary side possible.
Owing to the invention, measures do not need to be
taken either on the primary side or on the secondary
side in order to meet resonance conditions. Instead,
compensation of the wattless power can take place on
the primary side or secondary side, in particular
independently of the resonance condition.
The arrangement of the resonators on the primary side
and/or on the secondary side is of secondary importance
for the system to function. Instead, design-related
requirements, in particular physical sizes of the
target device and/or source device, can be taken into
consideration. It is advantageous if the energy source
16 has an AC voltage with a frequency in the region of
from 20 kHz to 5 MHz, preferably in the region of from
60 kHz to 500 kHz.
